diff options
Diffstat (limited to 'tools/objtool/check.c')
| -rw-r--r-- | tools/objtool/check.c | 3307 |
1 files changed, 2576 insertions, 731 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 4768d91c6d68..43ec14c29a60 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -5,20 +5,22 @@ #include <string.h> #include <stdlib.h> - -#include "builtin.h" -#include "check.h" -#include "elf.h" -#include "special.h" -#include "arch.h" -#include "warn.h" - +#include <inttypes.h> +#include <sys/mman.h> + +#include <arch/elf.h> +#include <objtool/builtin.h> +#include <objtool/cfi.h> +#include <objtool/arch.h> +#include <objtool/check.h> +#include <objtool/special.h> +#include <objtool/warn.h> +#include <objtool/endianness.h> + +#include <linux/objtool.h> #include <linux/hashtable.h> #include <linux/kernel.h> - -#define FAKE_JUMP_OFFSET -1 - -#define C_JUMP_TABLE_SECTION ".rodata..c_jump_table" +#include <linux/static_call_types.h> struct alternative { struct list_head list; @@ -26,17 +28,21 @@ struct alternative { bool skip_orig; }; -const char *objname; -struct cfi_state initial_func_cfi; +static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache; + +static struct cfi_init_state initial_func_cfi; +static struct cfi_state init_cfi; +static struct cfi_state func_cfi; struct instruction *find_insn(struct objtool_file *file, struct section *sec, unsigned long offset) { struct instruction *insn; - hash_for_each_possible(file->insn_hash, insn, hash, offset) + hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) { if (insn->sec == sec && insn->offset == offset) return insn; + } return NULL; } @@ -72,22 +78,33 @@ static struct instruction *next_insn_same_func(struct objtool_file *file, return find_insn(file, func->cfunc->sec, func->cfunc->offset); } -#define func_for_each_insn_all(file, func, insn) \ +static struct instruction *prev_insn_same_sym(struct objtool_file *file, + struct instruction *insn) +{ + struct instruction *prev = list_prev_entry(insn, list); + + if (&prev->list != &file->insn_list && prev->func == insn->func) + return prev; + + return NULL; +} + +#define func_for_each_insn(file, func, insn) \ for (insn = find_insn(file, func->sec, func->offset); \ insn; \ insn = next_insn_same_func(file, insn)) -#define func_for_each_insn(file, func, insn) \ - for (insn = find_insn(file, func->sec, func->offset); \ +#define sym_for_each_insn(file, sym, insn) \ + for (insn = find_insn(file, sym->sec, sym->offset); \ insn && &insn->list != &file->insn_list && \ - insn->sec == func->sec && \ - insn->offset < func->offset + func->len; \ + insn->sec == sym->sec && \ + insn->offset < sym->offset + sym->len; \ insn = list_next_entry(insn, list)) -#define func_for_each_insn_continue_reverse(file, func, insn) \ +#define sym_for_each_insn_continue_reverse(file, sym, insn) \ for (insn = list_prev_entry(insn, list); \ &insn->list != &file->insn_list && \ - insn->sec == func->sec && insn->offset >= func->offset; \ + insn->sec == sym->sec && insn->offset >= sym->offset; \ insn = list_prev_entry(insn, list)) #define sec_for_each_insn_from(file, insn) \ @@ -97,18 +114,34 @@ static struct instruction *next_insn_same_func(struct objtool_file *file, for (insn = next_insn_same_sec(file, insn); insn; \ insn = next_insn_same_sec(file, insn)) +static bool is_jump_table_jump(struct instruction *insn) +{ + struct alt_group *alt_group = insn->alt_group; + + if (insn->jump_table) + return true; + + /* Retpoline alternative for a jump table? */ + return alt_group && alt_group->orig_group && + alt_group->orig_group->first_insn->jump_table; +} + static bool is_sibling_call(struct instruction *insn) { + /* + * Assume only ELF functions can make sibling calls. This ensures + * sibling call detection consistency between vmlinux.o and individual + * objects. + */ + if (!insn->func) + return false; + /* An indirect jump is either a sibling call or a jump to a table. */ if (insn->type == INSN_JUMP_DYNAMIC) - return list_empty(&insn->alts); - - if (insn->type != INSN_JUMP_CONDITIONAL && - insn->type != INSN_JUMP_UNCONDITIONAL) - return false; + return !is_jump_table_jump(insn); /* add_jump_destinations() sets insn->call_dest for sibling calls. */ - return !!insn->call_dest; + return (is_static_jump(insn) && insn->call_dest); } /* @@ -129,22 +162,34 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, /* * Unfortunately these have to be hard coded because the noreturn - * attribute isn't provided in ELF data. + * attribute isn't provided in ELF data. Keep 'em sorted. */ static const char * const global_noreturns[] = { + "__invalid_creds", + "__module_put_and_kthread_exit", + "__reiserfs_panic", "__stack_chk_fail", - "panic", + "__ubsan_handle_builtin_unreachable", + "cpu_bringup_and_idle", + "cpu_startup_entry", "do_exit", + "do_group_exit", "do_task_dead", - "__module_put_and_exit", - "complete_and_exit", - "__reiserfs_panic", - "lbug_with_loc", + "ex_handler_msr_mce", "fortify_panic", - "usercopy_abort", - "machine_real_restart", - "rewind_stack_do_exit", + "kthread_complete_and_exit", + "kthread_exit", "kunit_try_catch_throw", + "lbug_with_loc", + "machine_real_restart", + "make_task_dead", + "panic", + "rewind_stack_and_make_dead", + "sev_es_terminate", + "snp_abort", + "stop_this_cpu", + "usercopy_abort", + "xen_start_kernel", }; if (!func) @@ -165,7 +210,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, if (!insn->func) return false; - func_for_each_insn_all(file, func, insn) { + func_for_each_insn(file, func, insn) { empty = false; if (insn->type == INSN_RETURN) @@ -180,7 +225,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, * case, the function's dead-end status depends on whether the target * of the sibling call returns. */ - func_for_each_insn_all(file, func, insn) { + func_for_each_insn(file, func, insn) { if (is_sibling_call(insn)) { struct instruction *dest = insn->jump_dest; @@ -210,20 +255,106 @@ static bool dead_end_function(struct objtool_file *file, struct symbol *func) return __dead_end_function(file, func, 0); } -static void clear_insn_state(struct insn_state *state) +static void init_cfi_state(struct cfi_state *cfi) { int i; - memset(state, 0, sizeof(*state)); - state->cfa.base = CFI_UNDEFINED; for (i = 0; i < CFI_NUM_REGS; i++) { - state->regs[i].base = CFI_UNDEFINED; - state->vals[i].base = CFI_UNDEFINED; + cfi->regs[i].base = CFI_UNDEFINED; + cfi->vals[i].base = CFI_UNDEFINED; + } + cfi->cfa.base = CFI_UNDEFINED; + cfi->drap_reg = CFI_UNDEFINED; + cfi->drap_offset = -1; +} + +static void init_insn_state(struct objtool_file *file, struct insn_state *state, + struct section *sec) +{ + memset(state, 0, sizeof(*state)); + init_cfi_state(&state->cfi); + + /* + * We need the full vmlinux for noinstr validation, otherwise we can + * not correctly determine insn->call_dest->sec (external symbols do + * not have a section). + */ + if (opts.link && opts.noinstr && sec) + state->noinstr = sec->noinstr; +} + +static struct cfi_state *cfi_alloc(void) +{ + struct cfi_state *cfi = calloc(sizeof(struct cfi_state), 1); + if (!cfi) { + WARN("calloc failed"); + exit(1); } - state->drap_reg = CFI_UNDEFINED; - state->drap_offset = -1; + nr_cfi++; + return cfi; +} + +static int cfi_bits; +static struct hlist_head *cfi_hash; + +static inline bool cficmp(struct cfi_state *cfi1, struct cfi_state *cfi2) +{ + return memcmp((void *)cfi1 + sizeof(cfi1->hash), + (void *)cfi2 + sizeof(cfi2->hash), + sizeof(struct cfi_state) - sizeof(struct hlist_node)); } +static inline u32 cfi_key(struct cfi_state *cfi) +{ + return jhash((void *)cfi + sizeof(cfi->hash), + sizeof(*cfi) - sizeof(cfi->hash), 0); +} + +static struct cfi_state *cfi_hash_find_or_add(struct cfi_state *cfi) +{ + struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)]; + struct cfi_state *obj; + + hlist_for_each_entry(obj, head, hash) { + if (!cficmp(cfi, obj)) { + nr_cfi_cache++; + return obj; + } + } + + obj = cfi_alloc(); + *obj = *cfi; + hlist_add_head(&obj->hash, head); + + return obj; +} + +static void cfi_hash_add(struct cfi_state *cfi) +{ + struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)]; + + hlist_add_head(&cfi->hash, head); +} + +static void *cfi_hash_alloc(unsigned long size) +{ + cfi_bits = max(10, ilog2(size)); + cfi_hash = mmap(NULL, sizeof(struct hlist_head) << cfi_bits, + PROT_READ|PROT_WRITE, + MAP_PRIVATE|MAP_ANON, -1, 0); + if (cfi_hash == (void *)-1L) { + WARN("mmap fail cfi_hash"); + cfi_hash = NULL; + } else if (opts.stats) { + printf("cfi_bits: %d\n", cfi_bits); + } + + return cfi_hash; +} + +static unsigned long nr_insns; +static unsigned long nr_insns_visited; + /* * Call the arch-specific instruction decoder for all the instructions and add * them to the global instruction list. @@ -246,7 +377,12 @@ static int decode_instructions(struct objtool_file *file) strncmp(sec->name, ".discard.", 9)) sec->text = true; - for (offset = 0; offset < sec->len; offset += insn->len) { + if (!strcmp(sec->name, ".noinstr.text") || + !strcmp(sec->name, ".entry.text") || + !strncmp(sec->name, ".text.__x86.", 12)) + sec->noinstr = true; + + for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) { insn = malloc(sizeof(*insn)); if (!insn) { WARN("malloc failed"); @@ -254,21 +390,31 @@ static int decode_instructions(struct objtool_file *file) } memset(insn, 0, sizeof(*insn)); INIT_LIST_HEAD(&insn->alts); - clear_insn_state(&insn->state); + INIT_LIST_HEAD(&insn->stack_ops); + INIT_LIST_HEAD(&insn->call_node); insn->sec = sec; insn->offset = offset; - ret = arch_decode_instruction(file->elf, sec, offset, - sec->len - offset, + ret = arch_decode_instruction(file, sec, offset, + sec->sh.sh_size - offset, &insn->len, &insn->type, &insn->immediate, - &insn->stack_op); + &insn->stack_ops); if (ret) goto err; - hash_add(file->insn_hash, &insn->hash, insn->offset); + /* + * By default, "ud2" is a dead end unless otherwise + * annotated, because GCC 7 inserts it for certain + * divide-by-zero cases. + */ + if (insn->type == INSN_BUG) + insn->dead_end = true; + + hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset)); list_add_tail(&insn->list, &file->insn_list); + nr_insns++; } list_for_each_entry(func, &sec->symbol_list, list) { @@ -281,11 +427,23 @@ static int decode_instructions(struct objtool_file *file) return -1; } - func_for_each_insn(file, func, insn) + sym_for_each_insn(file, func, insn) { insn->func = func; + if (insn->type == INSN_ENDBR && list_empty(&insn->call_node)) { + if (insn->offset == insn->func->offset) { + list_add_tail(&insn->call_node, &file->endbr_list); + file->nr_endbr++; + } else { + file->nr_endbr_int++; + } + } + } } } + if (opts.stats) + printf("nr_insns: %lu\n", nr_insns); + return 0; err: @@ -294,22 +452,102 @@ err: } /* + * Read the pv_ops[] .data table to find the static initialized values. + */ +static int add_pv_ops(struct objtool_file *file, const char *symname) +{ + struct symbol *sym, *func; + unsigned long off, end; + struct reloc *rel; + int idx; + + sym = find_symbol_by_name(file->elf, symname); + if (!sym) + return 0; + + off = sym->offset; + end = off + sym->len; + for (;;) { + rel = find_reloc_by_dest_range(file->elf, sym->sec, off, end - off); + if (!rel) + break; + + func = rel->sym; + if (func->type == STT_SECTION) + func = find_symbol_by_offset(rel->sym->sec, rel->addend); + + idx = (rel->offset - sym->offset) / sizeof(unsigned long); + + objtool_pv_add(file, idx, func); + + off = rel->offset + 1; + if (off > end) + break; + } + + return 0; +} + +/* + * Allocate and initialize file->pv_ops[]. + */ +static int init_pv_ops(struct objtool_file *file) +{ + static const char *pv_ops_tables[] = { + "pv_ops", + "xen_cpu_ops", + "xen_irq_ops", + "xen_mmu_ops", + NULL, + }; + const char *pv_ops; + struct symbol *sym; + int idx, nr; + + if (!opts.noinstr) + return 0; + + file->pv_ops = NULL; + + sym = find_symbol_by_name(file->elf, "pv_ops"); + if (!sym) + return 0; + + nr = sym->len / sizeof(unsigned long); + file->pv_ops = calloc(sizeof(struct pv_state), nr); + if (!file->pv_ops) + return -1; + + for (idx = 0; idx < nr; idx++) + INIT_LIST_HEAD(&file->pv_ops[idx].targets); + + for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++) + add_pv_ops(file, pv_ops); + + return 0; +} + +static struct instruction *find_last_insn(struct objtool_file *file, + struct section *sec) +{ + struct instruction *insn = NULL; + unsigned int offset; + unsigned int end = (sec->sh.sh_size > 10) ? sec->sh.sh_size - 10 : 0; + + for (offset = sec->sh.sh_size - 1; offset >= end && !insn; offset--) + insn = find_insn(file, sec, offset); + + return insn; +} + +/* * Mark "ud2" instructions and manually annotated dead ends. */ static int add_dead_ends(struct objtool_file *file) { struct section *sec; - struct rela *rela; + struct reloc *reloc; struct instruction *insn; - bool found; - - /* - * By default, "ud2" is a dead end unless otherwise annotated, because - * GCC 7 inserts it for certain divide-by-zero cases. - */ - for_each_insn(file, insn) - if (insn->type == INSN_BUG) - insn->dead_end = true; /* * Check for manually annotated dead ends. @@ -318,31 +556,24 @@ static int add_dead_ends(struct objtool_file *file) if (!sec) goto reachable; - list_for_each_entry(rela, &sec->rela_list, list) { - if (rela->sym->type != STT_SECTION) { + list_for_each_entry(reloc, &sec->reloc_list, list) { + if (reloc->sym->type != STT_SECTION) { WARN("unexpected relocation symbol type in %s", sec->name); return -1; } - insn = find_insn(file, rela->sym->sec, rela->addend); + insn = find_insn(file, reloc->sym->sec, reloc->addend); if (insn) insn = list_prev_entry(insn, list); - else if (rela->addend == rela->sym->sec->len) { - found = false; - list_for_each_entry_reverse(insn, &file->insn_list, list) { - if (insn->sec == rela->sym->sec) { - found = true; - break; - } - } - - if (!found) { - WARN("can't find unreachable insn at %s+0x%x", - rela->sym->sec->name, rela->addend); + else if (reloc->addend == reloc->sym->sec->sh.sh_size) { + insn = find_last_insn(file, reloc->sym->sec); + if (!insn) { + WARN("can't find unreachable insn at %s+0x%" PRIx64, + reloc->sym->sec->name, reloc->addend); return -1; } } else { - WARN("can't find unreachable insn at %s+0x%x", - rela->sym->sec->name, rela->addend); + WARN("can't find unreachable insn at %s+0x%" PRIx64, + reloc->sym->sec->name, reloc->addend); return -1; } @@ -360,31 +591,24 @@ reachable: if (!sec) return 0; - list_for_each_entry(rela, &sec->rela_list, list) { - if (rela->sym->type != STT_SECTION) { + list_for_each_entry(reloc, &sec->reloc_list, list) { + if (reloc->sym->type != STT_SECTION) { WARN("unexpected relocation symbol type in %s", sec->name); return -1; } - insn = find_insn(file, rela->sym->sec, rela->addend); + insn = find_insn(file, reloc->sym->sec, reloc->addend); if (insn) insn = list_prev_entry(insn, list); - else if (rela->addend == rela->sym->sec->len) { - found = false; - list_for_each_entry_reverse(insn, &file->insn_list, list) { - if (insn->sec == rela->sym->sec) { - found = true; - break; - } - } - - if (!found) { - WARN("can't find reachable insn at %s+0x%x", - rela->sym->sec->name, rela->addend); + else if (reloc->addend == reloc->sym->sec->sh.sh_size) { + insn = find_last_insn(file, reloc->sym->sec); + if (!insn) { + WARN("can't find reachable insn at %s+0x%" PRIx64, + reloc->sym->sec->name, reloc->addend); return -1; } } else { - WARN("can't find reachable insn at %s+0x%x", - rela->sym->sec->name, rela->addend); + WARN("can't find reachable insn at %s+0x%" PRIx64, + reloc->sym->sec->name, reloc->addend); return -1; } @@ -394,6 +618,281 @@ reachable: return 0; } +static int create_static_call_sections(struct objtool_file *file) +{ + struct section *sec; + struct static_call_site *site; + struct instruction *insn; + struct symbol *key_sym; + char *key_name, *tmp; + int idx; + + sec = find_section_by_name(file->elf, ".static_call_sites"); + if (sec) { + INIT_LIST_HEAD(&file->static_call_list); + WARN("file already has .static_call_sites section, skipping"); + return 0; + } + + if (list_empty(&file->static_call_list)) + return 0; + + idx = 0; + list_for_each_entry(insn, &file->static_call_list, call_node) + idx++; + + sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE, + sizeof(struct static_call_site), idx); + if (!sec) + return -1; + + idx = 0; + list_for_each_entry(insn, &file->static_call_list, call_node) { + + site = (struct static_call_site *)sec->data->d_buf + idx; + memset(site, 0, sizeof(struct static_call_site)); + + /* populate reloc for 'addr' */ + if (elf_add_reloc_to_insn(file->elf, sec, + idx * sizeof(struct static_call_site), + R_X86_64_PC32, + insn->sec, insn->offset)) + return -1; + + /* find key symbol */ + key_name = strdup(insn->call_dest->name); + if (!key_name) { + perror("strdup"); + return -1; + } + if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR, + STATIC_CALL_TRAMP_PREFIX_LEN)) { + WARN("static_call: trampoline name malformed: %s", key_name); + return -1; + } + tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN; + memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN); + + key_sym = find_symbol_by_name(file->elf, tmp); + if (!key_sym) { + if (!opts.module) { + WARN("static_call: can't find static_call_key symbol: %s", tmp); + return -1; + } + + /* + * For modules(), the key might not be exported, which + * means the module can make static calls but isn't + * allowed to change them. + * + * In that case we temporarily set the key to be the + * trampoline address. This is fixed up in + * static_call_add_module(). + */ + key_sym = insn->call_dest; + } + free(key_name); + + /* populate reloc for 'key' */ + if (elf_add_reloc(file->elf, sec, + idx * sizeof(struct static_call_site) + 4, + R_X86_64_PC32, key_sym, + is_sibling_call(insn) * STATIC_CALL_SITE_TAIL)) + return -1; + + idx++; + } + + return 0; +} + +static int create_retpoline_sites_sections(struct objtool_file *file) +{ + struct instruction *insn; + struct section *sec; + int idx; + + sec = find_section_by_name(file->elf, ".retpoline_sites"); + if (sec) { + WARN("file already has .retpoline_sites, skipping"); + return 0; + } + + idx = 0; + list_for_each_entry(insn, &file->retpoline_call_list, call_node) + idx++; + + if (!idx) + return 0; + + sec = elf_create_section(file->elf, ".retpoline_sites", 0, + sizeof(int), idx); + if (!sec) { + WARN("elf_create_section: .retpoline_sites"); + return -1; + } + + idx = 0; + list_for_each_entry(insn, &file->retpoline_call_list, call_node) { + + int *site = (int *)sec->data->d_buf + idx; + *site = 0; + + if (elf_add_reloc_to_insn(file->elf, sec, + idx * sizeof(int), + R_X86_64_PC32, + insn->sec, insn->offset)) { + WARN("elf_add_reloc_to_insn: .retpoline_sites"); + return -1; + } + + idx++; + } + + return 0; +} + +static int create_return_sites_sections(struct objtool_file *file) +{ + struct instruction *insn; + struct section *sec; + int idx; + + sec = find_section_by_name(file->elf, ".return_sites"); + if (sec) { + WARN("file already has .return_sites, skipping"); + return 0; + } + + idx = 0; + list_for_each_entry(insn, &file->return_thunk_list, call_node) + idx++; + + if (!idx) + return 0; + + sec = elf_create_section(file->elf, ".return_sites", 0, + sizeof(int), idx); + if (!sec) { + WARN("elf_create_section: .return_sites"); + return -1; + } + + idx = 0; + list_for_each_entry(insn, &file->return_thunk_list, call_node) { + + int *site = (int *)sec->data->d_buf + idx; + *site = 0; + + if (elf_add_reloc_to_insn(file->elf, sec, + idx * sizeof(int), + R_X86_64_PC32, + insn->sec, insn->offset)) { + WARN("elf_add_reloc_to_insn: .return_sites"); + return -1; + } + + idx++; + } + + return 0; +} + +static int create_ibt_endbr_seal_sections(struct objtool_file *file) +{ + struct instruction *insn; + struct section *sec; + int idx; + + sec = find_section_by_name(file->elf, ".ibt_endbr_seal"); + if (sec) { + WARN("file already has .ibt_endbr_seal, skipping"); + return 0; + } + + idx = 0; + list_for_each_entry(insn, &file->endbr_list, call_node) + idx++; + + if (opts.stats) { + printf("ibt: ENDBR at function start: %d\n", file->nr_endbr); + printf("ibt: ENDBR inside functions: %d\n", file->nr_endbr_int); + printf("ibt: superfluous ENDBR: %d\n", idx); + } + + if (!idx) + return 0; + + sec = elf_create_section(file->elf, ".ibt_endbr_seal", 0, + sizeof(int), idx); + if (!sec) { + WARN("elf_create_section: .ibt_endbr_seal"); + return -1; + } + + idx = 0; + list_for_each_entry(insn, &file->endbr_list, call_node) { + + int *site = (int *)sec->data->d_buf + idx; + *site = 0; + + if (elf_add_reloc_to_insn(file->elf, sec, + idx * sizeof(int), + R_X86_64_PC32, + insn->sec, insn->offset)) { + WARN("elf_add_reloc_to_insn: .ibt_endbr_seal"); + return -1; + } + + idx++; + } + + return 0; +} + +static int create_mcount_loc_sections(struct objtool_file *file) +{ + struct section *sec; + unsigned long *loc; + struct instruction *insn; + int idx; + + sec = find_section_by_name(file->elf, "__mcount_loc"); + if (sec) { + INIT_LIST_HEAD(&file->mcount_loc_list); + WARN("file already has __mcount_loc section, skipping"); + return 0; + } + + if (list_empty(&file->mcount_loc_list)) + return 0; + + idx = 0; + list_for_each_entry(insn, &file->mcount_loc_list, call_node) + idx++; + + sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx); + if (!sec) + return -1; + + idx = 0; + list_for_each_entry(insn, &file->mcount_loc_list, call_node) { + + loc = (unsigned long *)sec->data->d_buf + idx; + memset(loc, 0, sizeof(unsigned long)); + + if (elf_add_reloc_to_insn(file->elf, sec, + idx * sizeof(unsigned long), + R_X86_64_64, + insn->sec, insn->offset)) + return -1; + + idx++; + } + + return 0; +} + /* * Warnings shouldn't be reported for ignored functions. */ @@ -402,30 +901,30 @@ static void add_ignores(struct objtool_file *file) struct instruction *insn; struct section *sec; struct symbol *func; - struct rela *rela; + struct reloc *reloc; sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard"); if (!sec) return; - list_for_each_entry(rela, &sec->rela_list, list) { - switch (rela->sym->type) { + list_for_each_entry(reloc, &sec->reloc_list, list) { + switch (reloc->sym->type) { case STT_FUNC: - func = rela->sym; + func = reloc->sym; break; case STT_SECTION: - func = find_symbol_by_offset(rela->sym->sec, rela->addend); - if (!func || func->type != STT_FUNC) + func = find_func_by_offset(reloc->sym->sec, reloc->addend); + if (!func) continue; break; default: - WARN("unexpected relocation symbol type in %s: %d", sec->name, rela->sym->type); + WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type); continue; } - func_for_each_insn_all(file, func, insn) + func_for_each_insn(file, func, insn) insn->ignore = true; } } @@ -440,7 +939,7 @@ static void add_ignores(struct objtool_file *file) static const char *uaccess_safe_builtin[] = { /* KASAN */ "kasan_report", - "check_memory_region", + "kasan_check_range", /* KASAN out-of-line */ "__asan_loadN_noabort", "__asan_load1_noabort", @@ -454,6 +953,8 @@ static const char *uaccess_safe_builtin[] = { "__asan_store4_noabort", "__asan_store8_noabort", "__asan_store16_noabort", + "__kasan_check_read", + "__kasan_check_write", /* KASAN in-line */ "__asan_report_load_n_noabort", "__asan_report_load1_noabort", @@ -467,8 +968,90 @@ static const char *uaccess_safe_builtin[] = { "__asan_report_store4_noabort", "__asan_report_store8_noabort", "__asan_report_store16_noabort", + /* KCSAN */ + "__kcsan_check_access", + "__kcsan_mb", + "__kcsan_wmb", + "__kcsan_rmb", + "__kcsan_release", + "kcsan_found_watchpoint", + "kcsan_setup_watchpoint", + "kcsan_check_scoped_accesses", + "kcsan_disable_current", + "kcsan_enable_current_nowarn", + /* KCSAN/TSAN */ + "__tsan_func_entry", + "__tsan_func_exit", + "__tsan_read_range", + "__tsan_write_range", + "__tsan_read1", + "__tsan_read2", + "__tsan_read4", + "__tsan_read8", + "__tsan_read16", + "__tsan_write1", + "__tsan_write2", + "__tsan_write4", + "__tsan_write8", + "__tsan_write16", + "__tsan_read_write1", + "__tsan_read_write2", + "__tsan_read_write4", + "__tsan_read_write8", + "__tsan_read_write16", + "__tsan_atomic8_load", + "__tsan_atomic16_load", + "__tsan_atomic32_load", + "__tsan_atomic64_load", + "__tsan_atomic8_store", + "__tsan_atomic16_store", + "__tsan_atomic32_store", + "__tsan_atomic64_store", + "__tsan_atomic8_exchange", + "__tsan_atomic16_exchange", + "__tsan_atomic32_exchange", + "__tsan_atomic64_exchange", + "__tsan_atomic8_fetch_add", + "__tsan_atomic16_fetch_add", + "__tsan_atomic32_fetch_add", + "__tsan_atomic64_fetch_add", + "__tsan_atomic8_fetch_sub", + "__tsan_atomic16_fetch_sub", + "__tsan_atomic32_fetch_sub", + "__tsan_atomic64_fetch_sub", + "__tsan_atomic8_fetch_and", + "__tsan_atomic16_fetch_and", + "__tsan_atomic32_fetch_and", + "__tsan_atomic64_fetch_and", + "__tsan_atomic8_fetch_or", + "__tsan_atomic16_fetch_or", + "__tsan_atomic32_fetch_or", + "__tsan_atomic64_fetch_or", + "__tsan_atomic8_fetch_xor", + "__tsan_atomic16_fetch_xor", + "__tsan_atomic32_fetch_xor", + "__tsan_atomic64_fetch_xor", + "__tsan_atomic8_fetch_nand", + "__tsan_atomic16_fetch_nand", + "__tsan_atomic32_fetch_nand", + "__tsan_atomic64_fetch_nand", + "__tsan_atomic8_compare_exchange_strong", + "__tsan_atomic16_compare_exchange_strong", + "__tsan_atomic32_compare_exchange_strong", + "__tsan_atomic64_compare_exchange_strong", + "__tsan_atomic8_compare_exchange_weak", + "__tsan_atomic16_compare_exchange_weak", + "__tsan_atomic32_compare_exchange_weak", + "__tsan_atomic64_compare_exchange_weak", + "__tsan_atomic8_compare_exchange_val", + "__tsan_atomic16_compare_exchange_val", + "__tsan_atomic32_compare_exchange_val", + "__tsan_atomic64_compare_exchange_val", + "__tsan_atomic_thread_fence", + "__tsan_atomic_signal_fence", /* KCOV */ "write_comp_data", + "check_kcov_mode", "__sanitizer_cov_trace_pc", "__sanitizer_cov_trace_const_cmp1", "__sanitizer_cov_trace_const_cmp2", @@ -478,6 +1061,27 @@ static const char *uaccess_safe_builtin[] = { "__sanitizer_cov_trace_cmp2", "__sanitizer_cov_trace_cmp4", "__sanitizer_cov_trace_cmp8", + "__sanitizer_cov_trace_switch", + /* KMSAN */ + "kmsan_copy_to_user", + "kmsan_report", + "kmsan_unpoison_entry_regs", + "kmsan_unpoison_memory", + "__msan_chain_origin", + "__msan_get_context_state", + "__msan_instrument_asm_store", + "__msan_metadata_ptr_for_load_1", + "__msan_metadata_ptr_for_load_2", + "__msan_metadata_ptr_for_load_4", + "__msan_metadata_ptr_for_load_8", + "__msan_metadata_ptr_for_load_n", + "__msan_metadata_ptr_for_store_1", + "__msan_metadata_ptr_for_store_2", + "__msan_metadata_ptr_for_store_4", + "__msan_metadata_ptr_for_store_8", + "__msan_metadata_ptr_for_store_n", + "__msan_poison_alloca", + "__msan_warning", /* UBSAN */ "ubsan_type_mismatch_common", "__ubsan_handle_type_mismatch", @@ -485,9 +1089,13 @@ static const char *uaccess_safe_builtin[] = { "__ubsan_handle_shift_out_of_bounds", /* misc */ "csum_partial_copy_generic", - "__memcpy_mcsafe", - "mcsafe_handle_tail", + "copy_mc_fragile", + "copy_mc_fragile_handle_tail", + "copy_mc_enhanced_fast_string", "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */ + "clear_user_erms", + "clear_user_rep_good", + "clear_user_original", NULL }; @@ -496,7 +1104,7 @@ static void add_uaccess_safe(struct objtool_file *file) struct symbol *func; const char **name; - if (!uaccess) + if (!opts.uaccess) return; for (name = uaccess_safe_builtin; *name; name++) { @@ -517,20 +1125,20 @@ static void add_uaccess_safe(struct objtool_file *file) static int add_ignore_alternatives(struct objtool_file *file) { struct section *sec; - struct rela *rela; + struct reloc *reloc; struct instruction *insn; sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts"); if (!sec) return 0; - list_for_each_entry(rela, &sec->rela_list, list) { - if (rela->sym->type != STT_SECTION) { + list_for_each_entry(reloc, &sec->reloc_list, list) { + if (reloc->sym->type != STT_SECTION) { WARN("unexpected relocation symbol type in %s", sec->name); return -1; } - insn = find_insn(file, rela->sym->sec, rela->addend); + insn = find_insn(file, reloc->sym->sec, reloc->addend); if (!insn) { WARN("bad .discard.ignore_alts entry"); return -1; @@ -542,63 +1150,283 @@ static int add_ignore_alternatives(struct objtool_file *file) return 0; } +__weak bool arch_is_retpoline(struct symbol *sym) +{ + return false; +} + +__weak bool arch_is_rethunk(struct symbol *sym) +{ + return false; +} + +#define NEGATIVE_RELOC ((void *)-1L) + +static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn) +{ + if (insn->reloc == NEGATIVE_RELOC) + return NULL; + + if (!insn->reloc) { + if (!file) + return NULL; + + insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec, + insn->offset, insn->len); + if (!insn->reloc) { + insn->reloc = NEGATIVE_RELOC; + return NULL; + } + } + + return insn->reloc; +} + +static void remove_insn_ops(struct instruction *insn) +{ + struct stack_op *op, *tmp; + + list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) { + list_del(&op->list); + free(op); + } +} + +static void annotate_call_site(struct objtool_file *file, + struct instruction *insn, bool sibling) +{ + struct reloc *reloc = insn_reloc(file, insn); + struct symbol *sym = insn->call_dest; + + if (!sym) + sym = reloc->sym; + + /* + * Alternative replacement code is just template code which is + * sometimes copied to the original instruction. For now, don't + * annotate it. (In the future we might consider annotating the + * original instruction if/when it ever makes sense to do so.) + */ + if (!strcmp(insn->sec->name, ".altinstr_replacement")) + return; + + if (sym->static_call_tramp) { + list_add_tail(&insn->call_node, &file->static_call_list); + return; + } + + if (sym->retpoline_thunk) { + list_add_tail(&insn->call_node, &file->retpoline_call_list); + return; + } + + /* + * Many compilers cannot disable KCOV or sanitizer calls with a function + * attribute so they need a little help, NOP out any such calls from + * noinstr text. + */ + if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) { + if (reloc) { + reloc->type = R_NONE; + elf_write_reloc(file->elf, reloc); + } + + elf_write_insn(file->elf, insn->sec, + insn->offset, insn->len, + sibling ? arch_ret_insn(insn->len) + : arch_nop_insn(insn->len)); + + insn->type = sibling ? INSN_RETURN : INSN_NOP; + + if (sibling) { + /* + * We've replaced the tail-call JMP insn by two new + * insn: RET; INT3, except we only have a single struct + * insn here. Mark it retpoline_safe to avoid the SLS + * warning, instead of adding another insn. + */ + insn->retpoline_safe = true; + } + + return; + } + + if (opts.mcount && sym->fentry) { + if (sibling) + WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset); + + if (reloc) { + reloc->type = R_NONE; + elf_write_reloc(file->elf, reloc); + } + + elf_write_insn(file->elf, insn->sec, + insn->offset, insn->len, + arch_nop_insn(insn->len)); + + insn->type = INSN_NOP; + + list_add_tail(&insn->call_node, &file->mcount_loc_list); + return; + } + + if (!sibling && dead_end_function(file, sym)) + insn->dead_end = true; +} + +static void add_call_dest(struct objtool_file *file, struct instruction *insn, + struct symbol *dest, bool sibling) +{ + insn->call_dest = dest; + if (!dest) + return; + + /* + * Whatever stack impact regular CALLs have, should be undone + * by the RETURN of the called function. + * + * Annotated intra-function calls retain the stack_ops but + * are converted to JUMP, see read_intra_function_calls(). + */ + remove_insn_ops(insn); + + annotate_call_site(file, insn, sibling); +} + +static void add_retpoline_call(struct objtool_file *file, struct instruction *insn) +{ + /* + * Retpoline calls/jumps are really dynamic calls/jumps in disguise, + * so convert them accordingly. + */ + switch (insn->type) { + case INSN_CALL: + insn->type = INSN_CALL_DYNAMIC; + break; + case INSN_JUMP_UNCONDITIONAL: + insn->type = INSN_JUMP_DYNAMIC; + break; + case INSN_JUMP_CONDITIONAL: + insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL; + break; + default: + return; + } + + insn->retpoline_safe = true; + + /* + * Whatever stack impact regular CALLs have, should be undone + * by the RETURN of the called function. + * + * Annotated intra-function calls retain the stack_ops but + * are converted to JUMP, see read_intra_function_calls(). + */ + remove_insn_ops(insn); + + annotate_call_site(file, insn, false); +} + +static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add) +{ + /* + * Return thunk tail calls are really just returns in disguise, + * so convert them accordingly. + */ + insn->type = INSN_RETURN; + insn->retpoline_safe = true; + + if (add) + list_add_tail(&insn->call_node, &file->return_thunk_list); +} + +static bool same_function(struct instruction *insn1, struct instruction *insn2) +{ + return insn1->func->pfunc == insn2->func->pfunc; +} + +static bool is_first_func_insn(struct objtool_file *file, struct instruction *insn) +{ + if (insn->offset == insn->func->offset) + return true; + + if (opts.ibt) { + struct instruction *prev = prev_insn_same_sym(file, insn); + + if (prev && prev->type == INSN_ENDBR && + insn->offset == insn->func->offset + prev->len) + return true; + } + + return false; +} + /* * Find the destination instructions for all jumps. */ static int add_jump_destinations(struct objtool_file *file) { - struct instruction *insn; - struct rela *rela; + struct instruction *insn, *jump_dest; + struct reloc *reloc; struct section *dest_sec; unsigned long dest_off; for_each_insn(file, insn) { - if (insn->type != INSN_JUMP_CONDITIONAL && - insn->type != INSN_JUMP_UNCONDITIONAL) + if (insn->jump_dest) { + /* + * handle_group_alt() may have previously set + * 'jump_dest' for some alternatives. + */ continue; - - if (insn->ignore || insn->offset == FAKE_JUMP_OFFSET) + } + if (!is_static_jump(insn)) continue; - rela = find_rela_by_dest_range(insn->sec, insn->offset, - insn->len); - if (!rela) { + reloc = insn_reloc(file, insn); + if (!reloc) { dest_sec = insn->sec; - dest_off = insn->offset + insn->len + insn->immediate; - } else if (rela->sym->type == STT_SECTION) { - dest_sec = rela->sym->sec; - dest_off = rela->addend + 4; - } else if (rela->sym->sec->idx) { - dest_sec = rela->sym->sec; - dest_off = rela->sym->sym.st_value + rela->addend + 4; - } else if (strstr(rela->sym->name, "_indirect_thunk_")) { + dest_off = arch_jump_destination(insn); + } else if (reloc->sym->type == STT_SECTION) { + dest_sec = reloc->sym->sec; + dest_off = arch_dest_reloc_offset(reloc->addend); + } else if (reloc->sym->retpoline_thunk) { + add_retpoline_call(file, insn); + continue; + } else if (reloc->sym->return_thunk) { + add_return_call(file, insn, true); + continue; + } else if (insn->func) { /* - * Retpoline jumps are really dynamic jumps in - * disguise, so convert them accordingly. + * External sibling call or internal sibling call with + * STT_FUNC reloc. */ - if (insn->type == INSN_JUMP_UNCONDITIONAL) - insn->type = INSN_JUMP_DYNAMIC; - else - insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL; - - insn->retpoline_safe = true; + add_call_dest(file, insn, reloc->sym, true); continue; + } else if (reloc->sym->sec->idx) { + dest_sec = reloc->sym->sec; + dest_off = reloc->sym->sym.st_value + + arch_dest_reloc_offset(reloc->addend); } else { - /* external sibling call */ - insn->call_dest = rela->sym; + /* non-func asm code jumping to another file */ continue; } - insn->jump_dest = find_insn(file, dest_sec, dest_off); - if (!insn->jump_dest) { + jump_dest = find_insn(file, dest_sec, dest_off); + if (!jump_dest) { + struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off); /* - * This is a special case where an alt instruction - * jumps past the end of the section. These are - * handled later in handle_group_alt(). + * This is a special case for zen_untrain_ret(). + * It jumps to __x86_return_thunk(), but objtool + * can't find the thunk's starting RET + * instruction, because the RET is also in the + * middle of another instruction. Objtool only + * knows about the outer instruction. */ - if (!strcmp(insn->sec->name, ".altinstr_replacement")) + if (sym && sym->return_thunk) { + add_return_call(file, insn, false); continue; + } WARN_FUNC("can't find jump dest instruction at %s+0x%lx", insn->sec, insn->offset, dest_sec->name, @@ -609,8 +1437,8 @@ static int add_jump_destinations(struct objtool_file *file) /* * Cross-function jump. */ - if (insn->func && insn->jump_dest->func && - insn->func != insn->jump_dest->func) { + if (insn->func && jump_dest->func && + insn->func != jump_dest->func) { /* * For GCC 8+, create parent/child links for any cold @@ -627,23 +1455,39 @@ static int add_jump_destinations(struct objtool_file *file) * case where the parent function's only reference to a * subfunction is through a jump table. */ - if (!strstr(insn->func->name, ".cold.") && - strstr(insn->jump_dest->func->name, ".cold.")) { - insn->func->cfunc = insn->jump_dest->func; - insn->jump_dest->func->pfunc = insn->func; + if (!strstr(insn->func->name, ".cold") && + strstr(jump_dest->func->name, ".cold")) { + insn->func->cfunc = jump_dest->func; + jump_dest->func->pfunc = insn->func; - } else if (insn->jump_dest->func->pfunc != insn->func->pfunc && - insn->jump_dest->offset == insn->jump_dest->func->offset) { - - /* internal sibling call */ - insn->call_dest = insn->jump_dest->func; + } else if (!same_function(insn, jump_dest) && + is_first_func_insn(file, jump_dest)) { + /* + * Internal sibling call without reloc or with + * STT_SECTION reloc. + */ + add_call_dest(file, insn, jump_dest->func, true); + continue; } } + + insn->jump_dest = jump_dest; } return 0; } +static struct symbol *find_call_destination(struct section *sec, unsigned long offset) +{ + struct symbol *call_dest; + + call_dest = find_func_by_offset(sec, offset); + if (!call_dest) + call_dest = find_symbol_by_offset(sec, offset); + + return call_dest; +} + /* * Find the destination instructions for all calls. */ @@ -651,111 +1495,138 @@ static int add_call_destinations(struct objtool_file *file) { struct instruction *insn; unsigned long dest_off; - struct rela *rela; + struct symbol *dest; + struct reloc *reloc; for_each_insn(file, insn) { if (insn->type != INSN_CALL) continue; - rela = find_rela_by_dest_range(insn->sec, insn->offset, - insn->len); - if (!rela) { - dest_off = insn->offset + insn->len + insn->immediate; - insn->call_dest = find_symbol_by_offset(insn->sec, - dest_off); + reloc = insn_reloc(file, insn); + if (!reloc) { + dest_off = arch_jump_destination(insn); + dest = find_call_destination(insn->sec, dest_off); + + add_call_dest(file, insn, dest, false); + + if (insn->ignore) + continue; + + if (!insn->call_dest) { + WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset); + return -1; + } - if (!insn->call_dest && !insn->ignore) { - WARN_FUNC("unsupported intra-function call", + if (insn->func && insn->call_dest->type != STT_FUNC) { + WARN_FUNC("unsupported call to non-function", insn->sec, insn->offset); - if (retpoline) - WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE."); return -1; } - } else if (rela->sym->type == STT_SECTION) { - insn->call_dest = find_symbol_by_offset(rela->sym->sec, - rela->addend+4); - if (!insn->call_dest || - insn->call_dest->type != STT_FUNC) { - WARN_FUNC("can't find call dest symbol at %s+0x%x", + } else if (reloc->sym->type == STT_SECTION) { + dest_off = arch_dest_reloc_offset(reloc->addend); + dest = find_call_destination(reloc->sym->sec, dest_off); + if (!dest) { + WARN_FUNC("can't find call dest symbol at %s+0x%lx", insn->sec, insn->offset, - rela->sym->sec->name, - rela->addend + 4); + reloc->sym->sec->name, + dest_off); return -1; } + + add_call_dest(file, insn, dest, false); + + } else if (reloc->sym->retpoline_thunk) { + add_retpoline_call(file, insn); + } else - insn->call_dest = rela->sym; + add_call_dest(file, insn, reloc->sym, false); } return 0; } /* - * The .alternatives section requires some extra special care, over and above - * what other special sections require: - * - * 1. Because alternatives are patched in-place, we need to insert a fake jump - * instruction at the end so that validate_branch() skips all the original - * replaced instructions when validating the new instruction path. - * - * 2. An added wrinkle is that the new instruction length might be zero. In - * that case the old instructions are replaced with noops. We simulate that - * by creating a fake jump as the only new instruction. - * - * 3. In some cases, the alternative section includes an instruction which - * conditionally jumps to the _end_ of the entry. We have to modify these - * jumps' destinations to point back to .text rather than the end of the - * entry in .altinstr_replacement. + * The .alternatives section requires some extra special care over and above + * other special sections because alternatives are patched in place. */ static int handle_group_alt(struct objtool_file *file, struct special_alt *special_alt, struct instruction *orig_insn, struct instruction **new_insn) { - struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL; + struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL; + struct alt_group *orig_alt_group, *new_alt_group; unsigned long dest_off; + + orig_alt_group = malloc(sizeof(*orig_alt_group)); + if (!orig_alt_group) { + WARN("malloc failed"); + return -1; + } + orig_alt_group->cfi = calloc(special_alt->orig_len, + sizeof(struct cfi_state *)); + if (!orig_alt_group->cfi) { + WARN("calloc failed"); + return -1; + } + last_orig_insn = NULL; insn = orig_insn; sec_for_each_insn_from(file, insn) { if (insn->offset >= special_alt->orig_off + special_alt->orig_len) break; - insn->alt_group = true; + insn->alt_group = orig_alt_group; last_orig_insn = insn; } + orig_alt_group->orig_group = NULL; + orig_alt_group->first_insn = orig_insn; + orig_alt_group->last_insn = last_orig_insn; - if (next_insn_same_sec(file, last_orig_insn)) { - fake_jump = malloc(sizeof(*fake_jump)); - if (!fake_jump) { - WARN("malloc failed"); - return -1; - } - memset(fake_jump, 0, sizeof(*fake_jump)); - INIT_LIST_HEAD(&fake_jump->alts); - clear_insn_state(&fake_jump->state); - fake_jump->sec = special_alt->new_sec; - fake_jump->offset = FAKE_JUMP_OFFSET; - fake_jump->type = INSN_JUMP_UNCONDITIONAL; - fake_jump->jump_dest = list_next_entry(last_orig_insn, list); - fake_jump->func = orig_insn->func; + new_alt_group = malloc(sizeof(*new_alt_group)); + if (!new_alt_group) { + WARN("malloc failed"); + return -1; } - if (!special_alt->new_len) { - if (!fake_jump) { - WARN("%s: empty alternative at end of section", - special_alt->orig_sec->name); + if (special_alt->new_len < special_alt->orig_len) { + /* + * Insert a fake nop at the end to make the replacement + * alt_group the same size as the original. This is needed to + * allow propagate_alt_cfi() to do its magic. When the last + * instruction affects the stack, the instruction after it (the + * nop) will propagate the new state to the shared CFI array. + */ + nop = malloc(sizeof(*nop)); + if (!nop) { + WARN("malloc failed"); return -1; } + memset(nop, 0, sizeof(*nop)); + INIT_LIST_HEAD(&nop->alts); + INIT_LIST_HEAD(&nop->stack_ops); + + nop->sec = special_alt->new_sec; + nop->offset = special_alt->new_off + special_alt->new_len; + nop->len = special_alt->orig_len - special_alt->new_len; + nop->type = INSN_NOP; + nop->func = orig_insn->func; + nop->alt_group = new_alt_group; + nop->ignore = orig_insn->ignore_alts; + } - *new_insn = fake_jump; - return 0; + if (!special_alt->new_len) { + *new_insn = nop; + goto end; } - last_new_insn = NULL; insn = *new_insn; sec_for_each_insn_from(file, insn) { + struct reloc *alt_reloc; + if (insn->offset >= special_alt->new_off + special_alt->new_len) break; @@ -763,28 +1634,39 @@ static int handle_group_alt(struct objtool_file *file, insn->ignore = orig_insn->ignore_alts; insn->func = orig_insn->func; + insn->alt_group = new_alt_group; - if (insn->type != INSN_JUMP_CONDITIONAL && - insn->type != INSN_JUMP_UNCONDITIONAL) + /* + * Since alternative replacement code is copy/pasted by the + * kernel after applying relocations, generally such code can't + * have relative-address relocation references to outside the + * .altinstr_replacement section, unless the arch's + * alternatives code can adjust the relative offsets + * accordingly. + */ + alt_reloc = insn_reloc(file, insn); + if (alt_reloc && + !arch_support_alt_relocation(special_alt, insn, alt_reloc)) { + + WARN_FUNC("unsupported relocation in alternatives section", + insn->sec, insn->offset); + return -1; + } + + if (!is_static_jump(insn)) continue; if (!insn->immediate) continue; - dest_off = insn->offset + insn->len + insn->immediate; + dest_off = arch_jump_destination(insn); if (dest_off == special_alt->new_off + special_alt->new_len) { - if (!fake_jump) { - WARN("%s: alternative jump to end of section", - special_alt->orig_sec->name); + insn->jump_dest = next_insn_same_sec(file, last_orig_insn); + if (!insn->jump_dest) { + WARN_FUNC("can't find alternative jump destination", + insn->sec, insn->offset); return -1; } - insn->jump_dest = fake_jump; - } - - if (!insn->jump_dest) { - WARN_FUNC("can't find alternative jump destination", - insn->sec, insn->offset); - return -1; } } @@ -794,9 +1676,13 @@ static int handle_group_alt(struct objtool_file *file, return -1; } - if (fake_jump) - list_add(&fake_jump->list, &last_new_insn->list); - + if (nop) + list_add(&nop->list, &last_new_insn->list); +end: + new_alt_group->orig_group = orig_alt_group; + new_alt_group->first_insn = *new_insn; + new_alt_group->last_insn = nop ? : last_new_insn; + new_alt_group->cfi = orig_alt_group->cfi; return 0; } @@ -810,15 +1696,41 @@ static int handle_jump_alt(struct objtool_file *file, struct instruction *orig_insn, struct instruction **new_insn) { - if (orig_insn->type == INSN_NOP) - return 0; + if (orig_insn->type != INSN_JUMP_UNCONDITIONAL && + orig_insn->type != INSN_NOP) { - if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) { WARN_FUNC("unsupported instruction at jump label", orig_insn->sec, orig_insn->offset); return -1; } + if (opts.hack_jump_label && special_alt->key_addend & 2) { + struct reloc *reloc = insn_reloc(file, orig_insn); + + if (reloc) { + reloc->type = R_NONE; + elf_write_reloc(file->elf, reloc); + } + elf_write_insn(file->elf, orig_insn->sec, + orig_insn->offset, orig_insn->len, + arch_nop_insn(orig_insn->len)); + orig_insn->type = INSN_NOP; + } + + if (orig_insn->type == INSN_NOP) { + if (orig_insn->len == 2) + file->jl_nop_short++; + else + file->jl_nop_long++; + + return 0; + } + + if (orig_insn->len == 2) + file->jl_short++; + else + file->jl_long++; + *new_insn = list_next_entry(orig_insn, list); return 0; } @@ -866,6 +1778,12 @@ static int add_special_section_alts(struct objtool_file *file) } if (special_alt->group) { + if (!special_alt->orig_len) { + WARN_FUNC("empty alternative entry", + orig_insn->sec, orig_insn->offset); + continue; + } + ret = handle_group_alt(file, special_alt, orig_insn, &new_insn); if (ret) @@ -893,39 +1811,45 @@ static int add_special_section_alts(struct objtool_file *file) free(special_alt); } + if (opts.stats) { + printf("jl\\\tNOP\tJMP\n"); + printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short); + printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long); + } + out: return ret; } static int add_jump_table(struct objtool_file *file, struct instruction *insn, - struct rela *table) + struct reloc *table) { - struct rela *rela = table; + struct reloc *reloc = table; struct instruction *dest_insn; struct alternative *alt; struct symbol *pfunc = insn->func->pfunc; unsigned int prev_offset = 0; /* - * Each @rela is a switch table relocation which points to the target + * Each @reloc is a switch table relocation which points to the target * instruction. */ - list_for_each_entry_from(rela, &table->sec->rela_list, list) { + list_for_each_entry_from(reloc, &table->sec->reloc_list, list) { /* Check for the end of the table: */ - if (rela != table && rela->jump_table_start) + if (reloc != table && reloc->jump_table_start) break; /* Make sure the table entries are consecutive: */ - if (prev_offset && rela->offset != prev_offset + 8) + if (prev_offset && reloc->offset != prev_offset + 8) break; /* Detect function pointers from contiguous objects: */ - if (rela->sym->sec == pfunc->sec && - rela->addend == pfunc->offset) + if (reloc->sym->sec == pfunc->sec && + reloc->addend == pfunc->offset) break; - dest_insn = find_insn(file, rela->sym->sec, rela->addend); + dest_insn = find_insn(file, reloc->sym->sec, reloc->addend); if (!dest_insn) break; @@ -941,7 +1865,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn, alt->insn = dest_insn; list_add_tail(&alt->list, &insn->alts); - prev_offset = rela->offset; + prev_offset = reloc->offset; } if (!prev_offset) { @@ -954,56 +1878,15 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn, } /* - * find_jump_table() - Given a dynamic jump, find the switch jump table in - * .rodata associated with it. - * - * There are 3 basic patterns: - * - * 1. jmpq *[rodata addr](,%reg,8) - * - * This is the most common case by far. It jumps to an address in a simple - * jump table which is stored in .rodata. - * - * 2. jmpq *[rodata addr](%rip) - * - * This is caused by a rare GCC quirk, currently only seen in three driver - * functions in the kernel, only with certain obscure non-distro configs. - * - * As part of an optimization, GCC makes a copy of an existing switch jump - * table, modifies it, and then hard-codes the jump (albeit with an indirect - * jump) to use a single entry in the table. The rest of the jump table and - * some of its jump targets remain as dead code. - * - * In such a case we can just crudely ignore all unreachable instruction - * warnings for the entire object file. Ideally we would just ignore them - * for the function, but that would require redesigning the code quite a - * bit. And honestly that's just not worth doing: unreachable instruction - * warnings are of questionable value anyway, and this is such a rare issue. - * - * 3. mov [rodata addr],%reg1 - * ... some instructions ... - * jmpq *(%reg1,%reg2,8) - * - * This is a fairly uncommon pattern which is new for GCC 6. As of this - * writing, there are 11 occurrences of it in the allmodconfig kernel. - * - * As of GCC 7 there are quite a few more of these and the 'in between' code - * is significant. Esp. with KASAN enabled some of the code between the mov - * and jmpq uses .rodata itself, which can confuse things. - * - * TODO: Once we have DWARF CFI and smarter instruction decoding logic, - * ensure the same register is used in the mov and jump instructions. - * - * NOTE: RETPOLINE made it harder still to decode dynamic jumps. + * find_jump_table() - Given a dynamic jump, find the switch jump table + * associated with it. */ -static struct rela *find_jump_table(struct objtool_file *file, +static struct reloc *find_jump_table(struct objtool_file *file, struct symbol *func, struct instruction *insn) { - struct rela *text_rela, *table_rela; - struct instruction *orig_insn = insn; - struct section *table_sec; - unsigned long table_offset; + struct reloc *table_reloc; + struct instruction *dest_insn, *orig_insn = insn; /* * Backward search using the @first_jump_src links, these help avoid @@ -1011,11 +1894,8 @@ static struct rela *find_jump_table(struct objtool_file *file, * it. */ for (; - &insn->list != &file->insn_list && - insn->sec == func->sec && - insn->offset >= func->offset; - - insn = insn->first_jump_src ?: list_prev_entry(insn, list)) { + insn && insn->func && insn->func->pfunc == func; + insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) { if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC) break; @@ -1027,46 +1907,14 @@ static struct rela *find_jump_table(struct objtool_file *file, insn->jump_dest->offset > orig_insn->offset)) break; - /* look for a relocation which references .rodata */ - text_rela = find_rela_by_dest_range(insn->sec, insn->offset, - insn->len); - if (!text_rela || text_rela->sym->type != STT_SECTION || - !text_rela->sym->sec->rodata) + table_reloc = arch_find_switch_table(file, insn); + if (!table_reloc) continue; - - table_offset = text_rela->addend; - table_sec = text_rela->sym->sec; - - if (text_rela->type == R_X86_64_PC32) - table_offset += 4; - - /* - * Make sure the .rodata address isn't associated with a - * symbol. GCC jump tables are anonymous data. - * - * Also support C jump tables which are in the same format as - * switch jump tables. For objtool to recognize them, they - * need to be placed in the C_JUMP_TABLE_SECTION section. They - * have symbols associated with them. - */ - if (find_symbol_containing(table_sec, table_offset) && - strcmp(table_sec->name, C_JUMP_TABLE_SECTION)) - continue; - - /* Each table entry has a rela associated with it. */ - table_rela = find_rela_by_dest(table_sec, table_offset); - if (!table_rela) + dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend); + if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func) continue; - /* - * Use of RIP-relative switch jumps is quite rare, and - * indicates a rare GCC quirk/bug which can leave dead code - * behind. - */ - if (text_rela->type == R_X86_64_PC32) - file->ignore_unreachables = true; - - return table_rela; + return table_reloc; } return NULL; @@ -1080,9 +1928,9 @@ static void mark_func_jump_tables(struct objtool_file *file, struct symbol *func) { struct instruction *insn, *last = NULL; - struct rela *rela; + struct reloc *reloc; - func_for_each_insn_all(file, func, insn) { + func_for_each_insn(file, func, insn) { if (!last) last = insn; @@ -1103,10 +1951,10 @@ static void mark_func_jump_tables(struct objtool_file *file, if (insn->type != INSN_JUMP_DYNAMIC) continue; - rela = find_jump_table(file, func, insn); - if (rela) { - rela->jump_table_start = true; - insn->jump_table = rela; + reloc = find_jump_table(file, func, insn); + if (reloc) { + reloc->jump_table_start = true; + insn->jump_table = reloc; } } } @@ -1117,7 +1965,7 @@ static int add_func_jump_tables(struct objtool_file *file, struct instruction *insn; int ret; - func_for_each_insn_all(file, func, insn) { + func_for_each_insn(file, func, insn) { if (!insn->jump_table) continue; @@ -1158,95 +2006,128 @@ static int add_jump_table_alts(struct objtool_file *file) return 0; } +static void set_func_state(struct cfi_state *state) +{ + state->cfa = initial_func_cfi.cfa; + memcpy(&state->regs, &initial_func_cfi.regs, + CFI_NUM_REGS * sizeof(struct cfi_reg)); + state->stack_size = initial_func_cfi.cfa.offset; +} + static int read_unwind_hints(struct objtool_file *file) { - struct section *sec, *relasec; - struct rela *rela; + struct cfi_state cfi = init_cfi; + struct section *sec, *relocsec; struct unwind_hint *hint; struct instruction *insn; - struct cfi_reg *cfa; + struct reloc *reloc; int i; sec = find_section_by_name(file->elf, ".discard.unwind_hints"); if (!sec) return 0; - relasec = sec->rela; - if (!relasec) { + relocsec = sec->reloc; + if (!relocsec) { WARN("missing .rela.discard.unwind_hints section"); return -1; } - if (sec->len % sizeof(struct unwind_hint)) { + if (sec->sh.sh_size % sizeof(struct unwind_hint)) { WARN("struct unwind_hint size mismatch"); return -1; } file->hints = true; - for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) { + for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) { hint = (struct unwind_hint *)sec->data->d_buf + i; - rela = find_rela_by_dest(sec, i * sizeof(*hint)); - if (!rela) { - WARN("can't find rela for unwind_hints[%d]", i); + reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint)); + if (!reloc) { + WARN("can't find reloc for unwind_hints[%d]", i); return -1; } - insn = find_insn(file, rela->sym->sec, rela->addend); + insn = find_insn(file, reloc->sym->sec, reloc->addend); if (!insn) { WARN("can't find insn for unwind_hints[%d]", i); return -1; } - cfa = &insn->state.cfa; + insn->hint = true; if (hint->type == UNWIND_HINT_TYPE_SAVE) { + insn->hint = false; insn->save = true; continue; + } - } else if (hint->type == UNWIND_HINT_TYPE_RESTORE) { + if (hint->type == UNWIND_HINT_TYPE_RESTORE) { insn->restore = true; - insn->hint = true; continue; } - insn->hint = true; + if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) { + struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset); - switch (hint->sp_reg) { - case ORC_REG_UNDEFINED: - cfa->base = CFI_UNDEFINED; - break; - case ORC_REG_SP: - cfa->base = CFI_SP; - break; - case ORC_REG_BP: - cfa->base = CFI_BP; - break; - case ORC_REG_SP_INDIRECT: - cfa->base = CFI_SP_INDIRECT; - break; - case ORC_REG_R10: - cfa->base = CFI_R10; - break; - case ORC_REG_R13: - cfa->base = CFI_R13; - break; - case ORC_REG_DI: - cfa->base = CFI_DI; - break; - case ORC_REG_DX: - cfa->base = CFI_DX; - break; - default: + if (sym && sym->bind == STB_GLOBAL) { + if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) { + WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR", + insn->sec, insn->offset); + } + + insn->entry = 1; + } + } + + if (hint->type == UNWIND_HINT_TYPE_ENTRY) { + hint->type = UNWIND_HINT_TYPE_CALL; + insn->entry = 1; + } + + if (hint->type == UNWIND_HINT_TYPE_FUNC) { + insn->cfi = &func_cfi; + continue; + } + + if (insn->cfi) + cfi = *(insn->cfi); + + if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) { WARN_FUNC("unsupported unwind_hint sp base reg %d", insn->sec, insn->offset, hint->sp_reg); return -1; } - cfa->offset = hint->sp_offset; - insn->state.type = hint->type; - insn->state.end = hint->end; + cfi.cfa.offset = bswap_if_needed(hint->sp_offset); + cfi.type = hint->type; + cfi.end = hint->end; + + insn->cfi = cfi_hash_find_or_add(&cfi); + } + + return 0; +} + +static int read_noendbr_hints(struct objtool_file *file) +{ + struct section *sec; + struct instruction *insn; + struct reloc *reloc; + + sec = find_section_by_name(file->elf, ".rela.discard.noendbr"); + if (!sec) + return 0; + + list_for_each_entry(reloc, &sec->reloc_list, list) { + insn = find_insn(file, reloc->sym->sec, reloc->sym->offset + reloc->addend); + if (!insn) { + WARN("bad .discard.noendbr entry"); + return -1; + } + + insn->noendbr = 1; } return 0; @@ -1256,27 +2137,29 @@ static int read_retpoline_hints(struct objtool_file *file) { struct section *sec; struct instruction *insn; - struct rela *rela; + struct reloc *reloc; sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe"); if (!sec) return 0; - list_for_each_entry(rela, &sec->rela_list, list) { - if (rela->sym->type != STT_SECTION) { + list_for_each_entry(reloc, &sec->reloc_list, list) { + if (reloc->sym->type != STT_SECTION) { WARN("unexpected relocation symbol type in %s", sec->name); return -1; } - insn = find_insn(file, rela->sym->sec, rela->addend); + insn = find_insn(file, reloc->sym->sec, reloc->addend); if (!insn) { WARN("bad .discard.retpoline_safe entry"); return -1; } if (insn->type != INSN_JUMP_DYNAMIC && - insn->type != INSN_CALL_DYNAMIC) { - WARN_FUNC("retpoline_safe hint not an indirect jump/call", + insn->type != INSN_CALL_DYNAMIC && + insn->type != INSN_RETURN && + insn->type != INSN_NOP) { + WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret/nop", insn->sec, insn->offset); return -1; } @@ -1287,6 +2170,160 @@ static int read_retpoline_hints(struct objtool_file *file) return 0; } +static int read_instr_hints(struct objtool_file *file) +{ + struct section *sec; + struct instruction *insn; + struct reloc *reloc; + + sec = find_section_by_name(file->elf, ".rela.discard.instr_end"); + if (!sec) + return 0; + + list_for_each_entry(reloc, &sec->reloc_list, list) { + if (reloc->sym->type != STT_SECTION) { + WARN("unexpected relocation symbol type in %s", sec->name); + return -1; + } + + insn = find_insn(file, reloc->sym->sec, reloc->addend); + if (!insn) { + WARN("bad .discard.instr_end entry"); + return -1; + } + + insn->instr--; + } + + sec = find_section_by_name(file->elf, ".rela.discard.instr_begin"); + if (!sec) + return 0; + + list_for_each_entry(reloc, &sec->reloc_list, list) { + if (reloc->sym->type != STT_SECTION) { + WARN("unexpected relocation symbol type in %s", sec->name); + return -1; + } + + insn = find_insn(file, reloc->sym->sec, reloc->addend); + if (!insn) { + WARN("bad .discard.instr_begin entry"); + return -1; + } + + insn->instr++; + } + + return 0; +} + +static int read_intra_function_calls(struct objtool_file *file) +{ + struct instruction *insn; + struct section *sec; + struct reloc *reloc; + + sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls"); + if (!sec) + return 0; + + list_for_each_entry(reloc, &sec->reloc_list, list) { + unsigned long dest_off; + + if (reloc->sym->type != STT_SECTION) { + WARN("unexpected relocation symbol type in %s", + sec->name); + return -1; + } + + insn = find_insn(file, reloc->sym->sec, reloc->addend); + if (!insn) { + WARN("bad .discard.intra_function_call entry"); + return -1; + } + + if (insn->type != INSN_CALL) { + WARN_FUNC("intra_function_call not a direct call", + insn->sec, insn->offset); + return -1; + } + + /* + * Treat intra-function CALLs as JMPs, but with a stack_op. + * See add_call_destinations(), which strips stack_ops from + * normal CALLs. + */ + insn->type = INSN_JUMP_UNCONDITIONAL; + + dest_off = arch_jump_destination(insn); + insn->jump_dest = find_insn(file, insn->sec, dest_off); + if (!insn->jump_dest) { + WARN_FUNC("can't find call dest at %s+0x%lx", + insn->sec, insn->offset, + insn->sec->name, dest_off); + return -1; + } + } + + return 0; +} + +/* + * Return true if name matches an instrumentation function, where calls to that + * function from noinstr code can safely be removed, but compilers won't do so. + */ +static bool is_profiling_func(const char *name) +{ + /* + * Many compilers cannot disable KCOV with a function attribute. + */ + if (!strncmp(name, "__sanitizer_cov_", 16)) + return true; + + /* + * Some compilers currently do not remove __tsan_func_entry/exit nor + * __tsan_atomic_signal_fence (used for barrier instrumentation) with + * the __no_sanitize_thread attribute, remove them. Once the kernel's + * minimum Clang version is 14.0, this can be removed. + */ + if (!strncmp(name, "__tsan_func_", 12) || + !strcmp(name, "__tsan_atomic_signal_fence")) + return true; + + return false; +} + +static int classify_symbols(struct objtool_file *file) +{ + struct section *sec; + struct symbol *func; + + for_each_sec(file, sec) { + list_for_each_entry(func, &sec->symbol_list, list) { + if (func->bind != STB_GLOBAL) + continue; + + if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR, + strlen(STATIC_CALL_TRAMP_PREFIX_STR))) + func->static_call_tramp = true; + + if (arch_is_retpoline(func)) + func->retpoline_thunk = true; + + if (arch_is_rethunk(func)) + func->return_thunk = true; + + if (!strcmp(func->name, "__fentry__")) + func->fentry = true; + + if (is_profiling_func(func->name)) + func->profiling_func = true; + } + } + + return 0; +} + static void mark_rodata(struct objtool_file *file) { struct section *sec; @@ -1303,8 +2340,8 @@ static void mark_rodata(struct objtool_file *file) * .rodata.str1.* sections are ignored; they don't contain jump tables. */ for_each_sec(file, sec) { - if ((!strncmp(sec->name, ".rodata", 7) && !strstr(sec->name, ".str1.")) || - !strcmp(sec->name, C_JUMP_TABLE_SECTION)) { + if (!strncmp(sec->name, ".rodata", 7) && + !strstr(sec->name, ".str1.")) { sec->rodata = true; found = true; } @@ -1319,11 +2356,11 @@ static int decode_sections(struct objtool_file *file) mark_rodata(file); - ret = decode_instructions(file); + ret = init_pv_ops(file); if (ret) return ret; - ret = add_dead_ends(file); + ret = decode_instructions(file); if (ret) return ret; @@ -1334,18 +2371,52 @@ static int decode_sections(struct objtool_file *file) if (ret) return ret; - ret = add_jump_destinations(file); + /* + * Must be before read_unwind_hints() since that needs insn->noendbr. + */ + ret = read_noendbr_hints(file); + if (ret) + return ret; + + /* + * Must be before add_{jump_call}_destination. + */ + ret = classify_symbols(file); if (ret) return ret; + /* + * Must be before add_jump_destinations(), which depends on 'func' + * being set for alternatives, to enable proper sibling call detection. + */ ret = add_special_section_alts(file); if (ret) return ret; + ret = add_jump_destinations(file); + if (ret) + return ret; + + /* + * Must be before add_call_destination(); it changes INSN_CALL to + * INSN_JUMP. + */ + ret = read_intra_function_calls(file); + if (ret) + return ret; + ret = add_call_destinations(file); if (ret) return ret; + /* + * Must be after add_call_destinations() such that it can override + * dead_end_function() marks. + */ + ret = add_dead_ends(file); + if (ret) + return ret; + ret = add_jump_table_alts(file); if (ret) return ret; @@ -1358,55 +2429,75 @@ static int decode_sections(struct objtool_file *file) if (ret) return ret; + ret = read_instr_hints(file); + if (ret) + return ret; + return 0; } static bool is_fentry_call(struct instruction *insn) { if (insn->type == INSN_CALL && - insn->call_dest->type == STT_NOTYPE && - !strcmp(insn->call_dest->name, "__fentry__")) + insn->call_dest && + insn->call_dest->fentry) return true; return false; } -static bool has_modified_stack_frame(struct insn_state *state) +static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state) { + struct cfi_state *cfi = &state->cfi; int i; - if (state->cfa.base != initial_func_cfi.cfa.base || - state->cfa.offset != initial_func_cfi.cfa.offset || - state->stack_size != initial_func_cfi.cfa.offset || - state->drap) + if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap) + return true; + + if (cfi->cfa.offset != initial_func_cfi.cfa.offset) + return true; + + if (cfi->stack_size != initial_func_cfi.cfa.offset) return true; - for (i = 0; i < CFI_NUM_REGS; i++) - if (state->regs[i].base != initial_func_cfi.regs[i].base || - state->regs[i].offset != initial_func_cfi.regs[i].offset) + for (i = 0; i < CFI_NUM_REGS; i++) { + if (cfi->regs[i].base != initial_func_cfi.regs[i].base || + cfi->regs[i].offset != initial_func_cfi.regs[i].offset) return true; + } return false; } +static bool check_reg_frame_pos(const struct cfi_reg *reg, + int expected_offset) +{ + return reg->base == CFI_CFA && + reg->offset == expected_offset; +} + static bool has_valid_stack_frame(struct insn_state *state) { - if (state->cfa.base == CFI_BP && state->regs[CFI_BP].base == CFI_CFA && - state->regs[CFI_BP].offset == -16) + struct cfi_state *cfi = &state->cfi; + + if (cfi->cfa.base == CFI_BP && + check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) && + check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8)) return true; - if (state->drap && state->regs[CFI_BP].base == CFI_BP) + if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP) return true; return false; } -static int update_insn_state_regs(struct instruction *insn, struct insn_state *state) +static int update_cfi_state_regs(struct instruction *insn, + struct cfi_state *cfi, + struct stack_op *op) { - struct cfi_reg *cfa = &state->cfa; - struct stack_op *op = &insn->stack_op; + struct cfi_reg *cfa = &cfi->cfa; - if (cfa->base != CFI_SP) + if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT) return 0; /* push */ @@ -1425,20 +2516,19 @@ static int update_insn_state_regs(struct instruction *insn, struct insn_state *s return 0; } -static void save_reg(struct insn_state *state, unsigned char reg, int base, - int offset) +static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset) { if (arch_callee_saved_reg(reg) && - state->regs[reg].base == CFI_UNDEFINED) { - state->regs[reg].base = base; - state->regs[reg].offset = offset; + cfi->regs[reg].base == CFI_UNDEFINED) { + cfi->regs[reg].base = base; + cfi->regs[reg].offset = offset; } } -static void restore_reg(struct insn_state *state, unsigned char reg) +static void restore_reg(struct cfi_state *cfi, unsigned char reg) { - state->regs[reg].base = CFI_UNDEFINED; - state->regs[reg].offset = 0; + cfi->regs[reg].base = initial_func_cfi.regs[reg].base; + cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset; } /* @@ -1494,11 +2584,12 @@ static void restore_reg(struct insn_state *state, unsigned char reg) * 41 5d pop %r13 * c3 retq */ -static int update_insn_state(struct instruction *insn, struct insn_state *state) +static int update_cfi_state(struct instruction *insn, + struct instruction *next_insn, + struct cfi_state *cfi, struct stack_op *op) { - struct stack_op *op = &insn->stack_op; - struct cfi_reg *cfa = &state->cfa; - struct cfi_reg *regs = state->regs; + struct cfi_reg *cfa = &cfi->cfa; + struct cfi_reg *regs = cfi->regs; /* stack operations don't make sense with an undefined CFA */ if (cfa->base == CFI_UNDEFINED) { @@ -1509,8 +2600,9 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) return 0; } - if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET) - return update_insn_state_regs(insn, state); + if (cfi->type == UNWIND_HINT_TYPE_REGS || + cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL) + return update_cfi_state_regs(insn, cfi, op); switch (op->dest.type) { @@ -1520,21 +2612,20 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) case OP_SRC_REG: if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP && cfa->base == CFI_SP && - regs[CFI_BP].base == CFI_CFA && - regs[CFI_BP].offset == -cfa->offset) { + check_reg_frame_pos(®s[CFI_BP], -cfa->offset)) { /* mov %rsp, %rbp */ cfa->base = op->dest.reg; - state->bp_scratch = false; + cfi->bp_scratch = false; } else if (op->src.reg == CFI_SP && - op->dest.reg == CFI_BP && state->drap) { + op->dest.reg == CFI_BP && cfi->drap) { /* drap: mov %rsp, %rbp */ regs[CFI_BP].base = CFI_BP; - regs[CFI_BP].offset = -state->stack_size; - state->bp_scratch = false; + regs[CFI_BP].offset = -cfi->stack_size; + cfi->bp_scratch = false; } else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { @@ -1549,26 +2640,26 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) * ... * mov %rax, %rsp */ - state->vals[op->dest.reg].base = CFI_CFA; - state->vals[op->dest.reg].offset = -state->stack_size; + cfi->vals[op->dest.reg].base = CFI_CFA; + cfi->vals[op->dest.reg].offset = -cfi->stack_size; } else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP && - cfa->base == CFI_BP) { + (cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) { /* * mov %rbp, %rsp * * Restore the original stack pointer (Clang). */ - state->stack_size = -state->regs[CFI_BP].offset; + cfi->stack_size = -cfi->regs[CFI_BP].offset; } else if (op->dest.reg == cfa->base) { /* mov %reg, %rsp */ if (cfa->base == CFI_SP && - state->vals[op->src.reg].base == CFI_CFA) { + cfi->vals[op->src.reg].base == CFI_CFA) { /* * This is needed for the rare case @@ -1578,8 +2669,40 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) * ... * mov %rcx, %rsp */ - cfa->offset = -state->vals[op->src.reg].offset; - state->stack_size = cfa->offset; + cfa->offset = -cfi->vals[op->src.reg].offset; + cfi->stack_size = cfa->offset; + + } else if (cfa->base == CFI_SP && + cfi->vals[op->src.reg].base == CFI_SP_INDIRECT && + cfi->vals[op->src.reg].offset == cfa->offset) { + + /* + * Stack swizzle: + * + * 1: mov %rsp, (%[tos]) + * 2: mov %[tos], %rsp + * ... + * 3: pop %rsp + * + * Where: + * + * 1 - places a pointer to the previous + * stack at the Top-of-Stack of the + * new stack. + * + * 2 - switches to the new stack. + * + * 3 - pops the Top-of-Stack to restore + * the original stack. + * + * Note: we set base to SP_INDIRECT + * here and preserve offset. Therefore + * when the unwinder reaches ToS it + * will dereference SP and then add the + * offset to find the next frame, IOW: + * (%rsp) + offset. + */ + cfa->base = CFI_SP_INDIRECT; } else { cfa->base = CFI_UNDEFINED; @@ -1587,13 +2710,27 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) } } + else if (op->dest.reg == CFI_SP && + cfi->vals[op->src.reg].base == CFI_SP_INDIRECT && + cfi->vals[op->src.reg].offset == cfa->offset) { + + /* + * The same stack swizzle case 2) as above. But + * because we can't change cfa->base, case 3) + * will become a regular POP. Pretend we're a + * PUSH so things don't go unbalanced. + */ + cfi->stack_size += 8; + } + + break; case OP_SRC_ADD: if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) { /* add imm, %rsp */ - state->stack_size -= op->src.offset; + cfi->stack_size -= op->src.offset; if (cfa->base == CFI_SP) cfa->offset -= op->src.offset; break; @@ -1602,14 +2739,25 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) { /* lea disp(%rbp), %rsp */ - state->stack_size = -(op->src.offset + regs[CFI_BP].offset); + cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset); + break; + } + + if (!cfi->drap && op->src.reg == CFI_SP && + op->dest.reg == CFI_BP && cfa->base == CFI_SP && + check_reg_frame_pos(®s[CFI_BP], -cfa->offset + op->src.offset)) { + + /* lea disp(%rsp), %rbp */ + cfa->base = CFI_BP; + cfa->offset -= op->src.offset; + cfi->bp_scratch = false; break; } if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { /* drap: lea disp(%rsp), %drap */ - state->drap_reg = op->dest.reg; + cfi->drap_reg = op->dest.reg; /* * lea disp(%rsp), %reg @@ -1621,25 +2769,25 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) * ... * mov %rcx, %rsp */ - state->vals[op->dest.reg].base = CFI_CFA; - state->vals[op->dest.reg].offset = \ - -state->stack_size + op->src.offset; + cfi->vals[op->dest.reg].base = CFI_CFA; + cfi->vals[op->dest.reg].offset = \ + -cfi->stack_size + op->src.offset; break; } - if (state->drap && op->dest.reg == CFI_SP && - op->src.reg == state->drap_reg) { + if (cfi->drap && op->dest.reg == CFI_SP && + op->src.reg == cfi->drap_reg) { /* drap: lea disp(%drap), %rsp */ cfa->base = CFI_SP; - cfa->offset = state->stack_size = -op->src.offset; - state->drap_reg = CFI_UNDEFINED; - state->drap = false; + cfa->offset = cfi->stack_size = -op->src.offset; + cfi->drap_reg = CFI_UNDEFINED; + cfi->drap = false; break; } - if (op->dest.reg == state->cfa.base) { + if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) { WARN_FUNC("unsupported stack register modification", insn->sec, insn->offset); return -1; @@ -1649,18 +2797,18 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) case OP_SRC_AND: if (op->dest.reg != CFI_SP || - (state->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) || - (state->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) { + (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) || + (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) { WARN_FUNC("unsupported stack pointer realignment", insn->sec, insn->offset); return -1; } - if (state->drap_reg != CFI_UNDEFINED) { + if (cfi->drap_reg != CFI_UNDEFINED) { /* drap: and imm, %rsp */ - cfa->base = state->drap_reg; - cfa->offset = state->stack_size = 0; - state->drap = true; + cfa->base = cfi->drap_reg; + cfa->offset = cfi->stack_size = 0; + cfi->drap = true; } /* @@ -1672,57 +2820,76 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) case OP_SRC_POP: case OP_SRC_POPF: - if (!state->drap && op->dest.type == OP_DEST_REG && - op->dest.reg == cfa->base) { + if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) { + + /* pop %rsp; # restore from a stack swizzle */ + cfa->base = CFI_SP; + break; + } + + if (!cfi->drap && op->dest.reg == cfa->base) { /* pop %rbp */ cfa->base = CFI_SP; } - if (state->drap && cfa->base == CFI_BP_INDIRECT && - op->dest.type == OP_DEST_REG && - op->dest.reg == state->drap_reg && - state->drap_offset == -state->stack_size) { + if (cfi->drap && cfa->base == CFI_BP_INDIRECT && + op->dest.reg == cfi->drap_reg && + cfi->drap_offset == -cfi->stack_size) { /* drap: pop %drap */ - cfa->base = state->drap_reg; + cfa->base = cfi->drap_reg; cfa->offset = 0; - state->drap_offset = -1; + cfi->drap_offset = -1; - } else if (regs[op->dest.reg].offset == -state->stack_size) { + } else if (cfi->stack_size == -regs[op->dest.reg].offset) { /* pop %reg */ - restore_reg(state, op->dest.reg); + restore_reg(cfi, op->dest.reg); } - state->stack_size -= 8; + cfi->stack_size -= 8; if (cfa->base == CFI_SP) cfa->offset -= 8; break; case OP_SRC_REG_INDIRECT: - if (state->drap && op->src.reg == CFI_BP && - op->src.offset == state->drap_offset) { + if (!cfi->drap && op->dest.reg == cfa->base && + op->dest.reg == CFI_BP) { + + /* mov disp(%rsp), %rbp */ + cfa->base = CFI_SP; + cfa->offset = cfi->stack_size; + } + + if (cfi->drap && op->src.reg == CFI_BP && + op->src.offset == cfi->drap_offset) { /* drap: mov disp(%rbp), %drap */ - cfa->base = state->drap_reg; + cfa->base = cfi->drap_reg; cfa->offset = 0; - state->drap_offset = -1; + cfi->drap_offset = -1; } - if (state->drap && op->src.reg == CFI_BP && + if (cfi->drap && op->src.reg == CFI_BP && op->src.offset == regs[op->dest.reg].offset) { /* drap: mov disp(%rbp), %reg */ - restore_reg(state, op->dest.reg); + restore_reg(cfi, op->dest.reg); } else if (op->src.reg == cfa->base && op->src.offset == regs[op->dest.reg].offset + cfa->offset) { /* mov disp(%rbp), %reg */ /* mov disp(%rsp), %reg */ - restore_reg(state, op->dest.reg); + restore_reg(cfi, op->dest.reg); + + } else if (op->src.reg == CFI_SP && + op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) { + + /* mov disp(%rsp), %reg */ + restore_reg(cfi, op->dest.reg); } break; @@ -1737,91 +2904,81 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) case OP_DEST_PUSH: case OP_DEST_PUSHF: - state->stack_size += 8; + cfi->stack_size += 8; if (cfa->base == CFI_SP) cfa->offset += 8; if (op->src.type != OP_SRC_REG) break; - if (state->drap) { - if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) { + if (cfi->drap) { + if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) { /* drap: push %drap */ cfa->base = CFI_BP_INDIRECT; - cfa->offset = -state->stack_size; + cfa->offset = -cfi->stack_size; /* save drap so we know when to restore it */ - state->drap_offset = -state->stack_size; + cfi->drap_offset = -cfi->stack_size; - } else if (op->src.reg == CFI_BP && cfa->base == state->drap_reg) { + } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) { /* drap: push %rbp */ - state->stack_size = 0; + cfi->stack_size = 0; - } else if (regs[op->src.reg].base == CFI_UNDEFINED) { + } else { /* drap: push %reg */ - save_reg(state, op->src.reg, CFI_BP, -state->stack_size); + save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size); } } else { /* push %reg */ - save_reg(state, op->src.reg, CFI_CFA, -state->stack_size); + save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size); } /* detect when asm code uses rbp as a scratch register */ - if (!no_fp && insn->func && op->src.reg == CFI_BP && + if (opts.stackval && insn->func && op->src.reg == CFI_BP && cfa->base != CFI_BP) - state->bp_scratch = true; + cfi->bp_scratch = true; break; case OP_DEST_REG_INDIRECT: - if (state->drap) { - if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) { + if (cfi->drap) { + if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) { /* drap: mov %drap, disp(%rbp) */ cfa->base = CFI_BP_INDIRECT; cfa->offset = op->dest.offset; /* save drap offset so we know when to restore it */ - state->drap_offset = op->dest.offset; - } - - else if (regs[op->src.reg].base == CFI_UNDEFINED) { + cfi->drap_offset = op->dest.offset; + } else { /* drap: mov reg, disp(%rbp) */ - save_reg(state, op->src.reg, CFI_BP, op->dest.offset); + save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset); } } else if (op->dest.reg == cfa->base) { /* mov reg, disp(%rbp) */ /* mov reg, disp(%rsp) */ - save_reg(state, op->src.reg, CFI_CFA, - op->dest.offset - state->cfa.offset); - } + save_reg(cfi, op->src.reg, CFI_CFA, + op->dest.offset - cfi->cfa.offset); - break; + } else if (op->dest.reg == CFI_SP) { - case OP_DEST_LEAVE: - if ((!state->drap && cfa->base != CFI_BP) || - (state->drap && cfa->base != state->drap_reg)) { - WARN_FUNC("leave instruction with modified stack frame", - insn->sec, insn->offset); - return -1; - } - - /* leave (mov %rbp, %rsp; pop %rbp) */ + /* mov reg, disp(%rsp) */ + save_reg(cfi, op->src.reg, CFI_CFA, + op->dest.offset - cfi->stack_size); - state->stack_size = -state->regs[CFI_BP].offset - 8; - restore_reg(state, CFI_BP); + } else if (op->src.reg == CFI_SP && op->dest.offset == 0) { - if (!state->drap) { - cfa->base = CFI_SP; - cfa->offset -= 8; + /* mov %rsp, (%reg); # setup a stack swizzle. */ + cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT; + cfi->vals[op->dest.reg].offset = cfa->offset; } break; @@ -1834,7 +2991,7 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) } /* pop mem */ - state->stack_size -= 8; + cfi->stack_size -= 8; if (cfa->base == CFI_SP) cfa->offset -= 8; @@ -1849,41 +3006,126 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) return 0; } -static bool insn_state_match(struct instruction *insn, struct insn_state *state) +/* + * The stack layouts of alternatives instructions can sometimes diverge when + * they have stack modifications. That's fine as long as the potential stack + * layouts don't conflict at any given potential instruction boundary. + * + * Flatten the CFIs of the different alternative code streams (both original + * and replacement) into a single shared CFI array which can be used to detect + * conflicts and nicely feed a linear array of ORC entries to the unwinder. + */ +static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn) +{ + struct cfi_state **alt_cfi; + int group_off; + + if (!insn->alt_group) + return 0; + + if (!insn->cfi) { + WARN("CFI missing"); + return -1; + } + + alt_cfi = insn->alt_group->cfi; + group_off = insn->offset - insn->alt_group->first_insn->offset; + + if (!alt_cfi[group_off]) { + alt_cfi[group_off] = insn->cfi; + } else { + if (cficmp(alt_cfi[group_off], insn->cfi)) { + WARN_FUNC("stack layout conflict in alternatives", + insn->sec, insn->offset); + return -1; + } + } + + return 0; +} + +static int handle_insn_ops(struct instruction *insn, + struct instruction *next_insn, + struct insn_state *state) { - struct insn_state *state1 = &insn->state, *state2 = state; + struct stack_op *op; + + list_for_each_entry(op, &insn->stack_ops, list) { + + if (update_cfi_state(insn, next_insn, &state->cfi, op)) + return 1; + + if (!insn->alt_group) + continue; + + if (op->dest.type == OP_DEST_PUSHF) { + if (!state->uaccess_stack) { + state->uaccess_stack = 1; + } else if (state->uaccess_stack >> 31) { + WARN_FUNC("PUSHF stack exhausted", + insn->sec, insn->offset); + return 1; + } + state->uaccess_stack <<= 1; + state->uaccess_stack |= state->uaccess; + } + + if (op->src.type == OP_SRC_POPF) { + if (state->uaccess_stack) { + state->uaccess = state->uaccess_stack & 1; + state->uaccess_stack >>= 1; + if (state->uaccess_stack == 1) + state->uaccess_stack = 0; + } + } + } + + return 0; +} + +static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2) +{ + struct cfi_state *cfi1 = insn->cfi; int i; - if (memcmp(&state1->cfa, &state2->cfa, sizeof(state1->cfa))) { + if (!cfi1) { + WARN("CFI missing"); + return false; + } + + if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) { + WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d", insn->sec, insn->offset, - state1->cfa.base, state1->cfa.offset, - state2->cfa.base, state2->cfa.offset); + cfi1->cfa.base, cfi1->cfa.offset, + cfi2->cfa.base, cfi2->cfa.offset); - } else if (memcmp(&state1->regs, &state2->regs, sizeof(state1->regs))) { + } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) { for (i = 0; i < CFI_NUM_REGS; i++) { - if (!memcmp(&state1->regs[i], &state2->regs[i], + if (!memcmp(&cfi1->regs[i], &cfi2->regs[i], sizeof(struct cfi_reg))) continue; WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d", insn->sec, insn->offset, - i, state1->regs[i].base, state1->regs[i].offset, - i, state2->regs[i].base, state2->regs[i].offset); + i, cfi1->regs[i].base, cfi1->regs[i].offset, + i, cfi2->regs[i].base, cfi2->regs[i].offset); break; } - } else if (state1->type != state2->type) { + } else if (cfi1->type != cfi2->type) { + WARN_FUNC("stack state mismatch: type1=%d type2=%d", - insn->sec, insn->offset, state1->type, state2->type); + insn->sec, insn->offset, cfi1->type, cfi2->type); + + } else if (cfi1->drap != cfi2->drap || + (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) || + (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) { - } else if (state1->drap != state2->drap || - (state1->drap && state1->drap_reg != state2->drap_reg) || - (state1->drap && state1->drap_offset != state2->drap_offset)) { WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)", insn->sec, insn->offset, - state1->drap, state1->drap_reg, state1->drap_offset, - state2->drap, state2->drap_reg, state2->drap_offset); + cfi1->drap, cfi1->drap_reg, cfi1->drap_offset, + cfi2->drap, cfi2->drap_reg, cfi2->drap_offset); } else return true; @@ -1901,14 +3143,93 @@ static inline bool func_uaccess_safe(struct symbol *func) static inline const char *call_dest_name(struct instruction *insn) { + static char pvname[19]; + struct reloc *rel; + int idx; + if (insn->call_dest) return insn->call_dest->name; + rel = insn_reloc(NULL, insn); + if (rel && !strcmp(rel->sym->name, "pv_ops")) { + idx = (rel->addend / sizeof(void *)); + snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx); + return pvname; + } + return "{dynamic}"; } -static int validate_call(struct instruction *insn, struct insn_state *state) +static bool pv_call_dest(struct objtool_file *file, struct instruction *insn) +{ + struct symbol *target; + struct reloc *rel; + int idx; + + rel = insn_reloc(file, insn); + if (!rel || strcmp(rel->sym->name, "pv_ops")) + return false; + + idx = (arch_dest_reloc_offset(rel->addend) / sizeof(void *)); + + if (file->pv_ops[idx].clean) + return true; + + file->pv_ops[idx].clean = true; + + list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) { + if (!target->sec->noinstr) { + WARN("pv_ops[%d]: %s", idx, target->name); + file->pv_ops[idx].clean = false; + } + } + + return file->pv_ops[idx].clean; +} + +static inline bool noinstr_call_dest(struct objtool_file *file, + struct instruction *insn, + struct symbol *func) { + /* + * We can't deal with indirect function calls at present; + * assume they're instrumented. + */ + if (!func) { + if (file->pv_ops) + return pv_call_dest(file, insn); + + return false; + } + + /* + * If the symbol is from a noinstr section; we good. + */ + if (func->sec->noinstr) + return true; + + /* + * The __ubsan_handle_*() calls are like WARN(), they only happen when + * something 'BAD' happened. At the risk of taking the machine down, + * let them proceed to get the message out. + */ + if (!strncmp(func->name, "__ubsan_handle_", 15)) + return true; + + return false; +} + +static int validate_call(struct objtool_file *file, + struct instruction *insn, + struct insn_state *state) +{ + if (state->noinstr && state->instr <= 0 && + !noinstr_call_dest(file, insn, insn->call_dest)) { + WARN_FUNC("call to %s() leaves .noinstr.text section", + insn->sec, insn->offset, call_dest_name(insn)); + return 1; + } + if (state->uaccess && !func_uaccess_safe(insn->call_dest)) { WARN_FUNC("call to %s() with UACCESS enabled", insn->sec, insn->offset, call_dest_name(insn)); @@ -1924,45 +3245,101 @@ static int validate_call(struct instruction *insn, struct insn_state *state) return 0; } -static int validate_sibling_call(struct instruction *insn, struct insn_state *state) +static int validate_sibling_call(struct objtool_file *file, + struct instruction *insn, + struct insn_state *state) { - if (has_modified_stack_frame(state)) { + if (has_modified_stack_frame(insn, state)) { WARN_FUNC("sibling call from callable instruction with modified stack frame", insn->sec, insn->offset); return 1; } - return validate_call(insn, state); + return validate_call(file, insn, state); +} + +static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state) +{ + if (state->noinstr && state->instr > 0) { + WARN_FUNC("return with instrumentation enabled", + insn->sec, insn->offset); + return 1; + } + + if (state->uaccess && !func_uaccess_safe(func)) { + WARN_FUNC("return with UACCESS enabled", + insn->sec, insn->offset); + return 1; + } + + if (!state->uaccess && func_uaccess_safe(func)) { + WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function", + insn->sec, insn->offset); + return 1; + } + + if (state->df) { + WARN_FUNC("return with DF set", + insn->sec, insn->offset); + return 1; + } + + if (func && has_modified_stack_frame(insn, state)) { + WARN_FUNC("return with modified stack frame", + insn->sec, insn->offset); + return 1; + } + + if (state->cfi.bp_scratch) { + WARN_FUNC("BP used as a scratch register", + insn->sec, insn->offset); + return 1; + } + + return 0; +} + +static struct instruction *next_insn_to_validate(struct objtool_file *file, + struct instruction *insn) +{ + struct alt_group *alt_group = insn->alt_group; + + /* + * Simulate the fact that alternatives are patched in-place. When the + * end of a replacement alt_group is reached, redirect objtool flow to + * the end of the original alt_group. + */ + if (alt_group && insn == alt_group->last_insn && alt_group->orig_group) + return next_insn_same_sec(file, alt_group->orig_group->last_insn); + + return next_insn_same_sec(file, insn); } /* * Follow the branch starting at the given instruction, and recursively follow * any other branches (jumps). Meanwhile, track the frame pointer state at * each instruction and validate all the rules described in - * tools/objtool/Documentation/stack-validation.txt. + * tools/objtool/Documentation/objtool.txt. */ static int validate_branch(struct objtool_file *file, struct symbol *func, - struct instruction *first, struct insn_state state) + struct instruction *insn, struct insn_state state) { struct alternative *alt; - struct instruction *insn, *next_insn; + struct instruction *next_insn, *prev_insn = NULL; struct section *sec; u8 visited; int ret; - insn = first; sec = insn->sec; - if (insn->alt_group && list_empty(&insn->alts)) { - WARN_FUNC("don't know how to handle branch to middle of alternative instruction group", - sec, insn->offset); - return 1; - } - while (1) { - next_insn = next_insn_same_sec(file, insn); + next_insn = next_insn_to_validate(file, insn); + + if (func && insn->func && func != insn->func->pfunc) { + /* Ignore KCFI type preambles, which always fall through */ + if (!strncmp(func->name, "__cfi_", 6)) + return 0; - if (file->c_file && func && insn->func && func != insn->func->pfunc) { WARN("%s() falls through to next function %s()", func->name, insn->func->name); return 1; @@ -1974,22 +3351,28 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, return 1; } - visited = 1 << state.uaccess; - if (insn->visited) { - if (!insn->hint && !insn_state_match(insn, &state)) + visited = VISITED_BRANCH << state.uaccess; + if (insn->visited & VISITED_BRANCH_MASK) { + if (!insn->hint && !insn_cfi_match(insn, &state.cfi)) return 1; if (insn->visited & visited) return 0; + } else { + nr_insns_visited++; } + if (state.noinstr) + state.instr += insn->instr; + if (insn->hint) { if (insn->restore) { struct instruction *save_insn, *i; i = insn; save_insn = NULL; - func_for_each_insn_continue_reverse(file, func, i) { + + sym_for_each_insn_continue_reverse(file, func, i) { if (i->save) { save_insn = i; break; @@ -2003,32 +3386,33 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, } if (!save_insn->visited) { - /* - * Oops, no state to copy yet. - * Hopefully we can reach this - * instruction from another branch - * after the save insn has been - * visited. - */ - if (insn == first) - return 0; - WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo", sec, insn->offset); return 1; } - insn->state = save_insn->state; + insn->cfi = save_insn->cfi; + nr_cfi_reused++; } - state = insn->state; + state.cfi = *insn->cfi; + } else { + /* XXX track if we actually changed state.cfi */ - } else - insn->state = state; + if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) { + insn->cfi = prev_insn->cfi; + nr_cfi_reused++; + } else { + insn->cfi = cfi_hash_find_or_add(&state.cfi); + } + } insn->visited |= visited; - if (!insn->ignore_alts) { + if (propagate_alt_cfi(file, insn)) + return 1; + + if (!insn->ignore_alts && !list_empty(&insn->alts)) { bool skip_orig = false; list_for_each_entry(alt, &insn->alts, list) { @@ -2037,7 +3421,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, ret = validate_branch(file, func, alt->insn, state); if (ret) { - if (backtrace) + if (opts.backtrace) BT_FUNC("(alt)", insn); return ret; } @@ -2047,60 +3431,36 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, return 0; } + if (handle_insn_ops(insn, next_insn, &state)) + return 1; + switch (insn->type) { case INSN_RETURN: - if (state.uaccess && !func_uaccess_safe(func)) { - WARN_FUNC("return with UACCESS enabled", sec, insn->offset); - return 1; - } - - if (!state.uaccess && func_uaccess_safe(func)) { - WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function", sec, insn->offset); - return 1; - } - - if (state.df) { - WARN_FUNC("return with DF set", sec, insn->offset); - return 1; - } - - if (func && has_modified_stack_frame(&state)) { - WARN_FUNC("return with modified stack frame", - sec, insn->offset); - return 1; - } - - if (state.bp_scratch) { - WARN("%s uses BP as a scratch register", - func->name); - return 1; - } - - return 0; + return validate_return(func, insn, &state); case INSN_CALL: case INSN_CALL_DYNAMIC: - ret = validate_call(insn, &state); + ret = validate_call(file, insn, &state); if (ret) return ret; - if (!no_fp && func && !is_fentry_call(insn) && + if (opts.stackval && func && !is_fentry_call(insn) && !has_valid_stack_frame(&state)) { WARN_FUNC("call without frame pointer save/setup", sec, insn->offset); return 1; } - if (dead_end_function(file, insn->call_dest)) + if (insn->dead_end) return 0; break; case INSN_JUMP_CONDITIONAL: case INSN_JUMP_UNCONDITIONAL: - if (func && is_sibling_call(insn)) { - ret = validate_sibling_call(insn, &state); + if (is_sibling_call(insn)) { + ret = validate_sibling_call(file, insn, &state); if (ret) return ret; @@ -2108,7 +3468,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, ret = validate_branch(file, func, insn->jump_dest, state); if (ret) { - if (backtrace) + if (opts.backtrace) BT_FUNC("(branch)", insn); return ret; } @@ -2121,8 +3481,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, case INSN_JUMP_DYNAMIC: case INSN_JUMP_DYNAMIC_CONDITIONAL: - if (func && is_sibling_call(insn)) { - ret = validate_sibling_call(insn, &state); + if (is_sibling_call(insn)) { + ret = validate_sibling_call(file, insn, &state); if (ret) return ret; } @@ -2140,32 +3500,6 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, } return 0; - case INSN_STACK: - if (update_insn_state(insn, &state)) - return 1; - - if (insn->stack_op.dest.type == OP_DEST_PUSHF) { - if (!state.uaccess_stack) { - state.uaccess_stack = 1; - } else if (state.uaccess_stack >> 31) { - WARN_FUNC("PUSHF stack exhausted", sec, insn->offset); - return 1; - } - state.uaccess_stack <<= 1; - state.uaccess_stack |= state.uaccess; - } - - if (insn->stack_op.src.type == OP_SRC_POPF) { - if (state.uaccess_stack) { - state.uaccess = state.uaccess_stack & 1; - state.uaccess_stack >>= 1; - if (state.uaccess_stack == 1) - state.uaccess_stack = 0; - } - } - - break; - case INSN_STAC: if (state.uaccess) { WARN_FUNC("recursive UACCESS enable", sec, insn->offset); @@ -2190,15 +3524,19 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, break; case INSN_STD: - if (state.df) + if (state.df) { WARN_FUNC("recursive STD", sec, insn->offset); + return 1; + } state.df = true; break; case INSN_CLD: - if (!state.df && func) + if (!state.df && func) { WARN_FUNC("redundant CLD", sec, insn->offset); + return 1; + } state.df = false; break; @@ -2211,36 +3549,186 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, return 0; if (!next_insn) { - if (state.cfa.base == CFI_UNDEFINED) + if (state.cfi.cfa.base == CFI_UNDEFINED) return 0; WARN("%s: unexpected end of section", sec->name); return 1; } + prev_insn = insn; insn = next_insn; } return 0; } -static int validate_unwind_hints(struct objtool_file *file) +static int validate_unwind_hints(struct objtool_file *file, struct section *sec) { struct instruction *insn; - int ret, warnings = 0; struct insn_state state; + int ret, warnings = 0; if (!file->hints) return 0; - clear_insn_state(&state); + init_insn_state(file, &state, sec); - for_each_insn(file, insn) { - if (insn->hint && !insn->visited) { + if (sec) { + insn = find_insn(file, sec, 0); + if (!insn) + return 0; + } else { + insn = list_first_entry(&file->insn_list, typeof(*insn), list); + } + + while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) { + if (insn->hint && !insn->visited && !insn->ignore) { ret = validate_branch(file, insn->func, insn, state); - if (ret && backtrace) + if (ret && opts.backtrace) BT_FUNC("<=== (hint)", insn); warnings += ret; } + + insn = list_next_entry(insn, list); + } + + return warnings; +} + +/* + * Validate rethunk entry constraint: must untrain RET before the first RET. + * + * Follow every branch (intra-function) and ensure ANNOTATE_UNRET_END comes + * before an actual RET instruction. + */ +static int validate_entry(struct objtool_file *file, struct instruction *insn) +{ + struct instruction *next, *dest; + int ret, warnings = 0; + + for (;;) { + next = next_insn_to_validate(file, insn); + + if (insn->visited & VISITED_ENTRY) + return 0; + + insn->visited |= VISITED_ENTRY; + + if (!insn->ignore_alts && !list_empty(&insn->alts)) { + struct alternative *alt; + bool skip_orig = false; + + list_for_each_entry(alt, &insn->alts, list) { + if (alt->skip_orig) + skip_orig = true; + + ret = validate_entry(file, alt->insn); + if (ret) { + if (opts.backtrace) + BT_FUNC("(alt)", insn); + return ret; + } + } + + if (skip_orig) + return 0; + } + + switch (insn->type) { + + case INSN_CALL_DYNAMIC: + case INSN_JUMP_DYNAMIC: + case INSN_JUMP_DYNAMIC_CONDITIONAL: + WARN_FUNC("early indirect call", insn->sec, insn->offset); + return 1; + + case INSN_JUMP_UNCONDITIONAL: + case INSN_JUMP_CONDITIONAL: + if (!is_sibling_call(insn)) { + if (!insn->jump_dest) { + WARN_FUNC("unresolved jump target after linking?!?", + insn->sec, insn->offset); + return -1; + } + ret = validate_entry(file, insn->jump_dest); + if (ret) { + if (opts.backtrace) { + BT_FUNC("(branch%s)", insn, + insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : ""); + } + return ret; + } + + if (insn->type == INSN_JUMP_UNCONDITIONAL) + return 0; + + break; + } + + /* fallthrough */ + case INSN_CALL: + dest = find_insn(file, insn->call_dest->sec, + insn->call_dest->offset); + if (!dest) { + WARN("Unresolved function after linking!?: %s", + insn->call_dest->name); + return -1; + } + + ret = validate_entry(file, dest); + if (ret) { + if (opts.backtrace) + BT_FUNC("(call)", insn); + return ret; + } + /* + * If a call returns without error, it must have seen UNTRAIN_RET. + * Therefore any non-error return is a success. + */ + return 0; + + case INSN_RETURN: + WARN_FUNC("RET before UNTRAIN", insn->sec, insn->offset); + return 1; + + case INSN_NOP: + if (insn->retpoline_safe) + return 0; + break; + + default: + break; + } + + if (!next) { + WARN_FUNC("teh end!", insn->sec, insn->offset); + return -1; + } + insn = next; + } + + return warnings; +} + +/* + * Validate that all branches starting at 'insn->entry' encounter UNRET_END + * before RET. + */ +static int validate_unret(struct objtool_file *file) +{ + struct instruction *insn; + int ret, warnings = 0; + + for_each_insn(file, insn) { + if (!insn->entry) + continue; + + ret = validate_entry(file, insn); + if (ret < 0) { + WARN_FUNC("Failed UNRET validation", insn->sec, insn->offset); + return ret; + } + warnings += ret; } return warnings; @@ -2253,7 +3741,8 @@ static int validate_retpoline(struct objtool_file *file) for_each_insn(file, insn) { if (insn->type != INSN_JUMP_DYNAMIC && - insn->type != INSN_CALL_DYNAMIC) + insn->type != INSN_CALL_DYNAMIC && + insn->type != INSN_RETURN) continue; if (insn->retpoline_safe) @@ -2265,12 +3754,20 @@ static int validate_retpoline(struct objtool_file *file) * loaded late, they very much do need retpoline in their * .init.text */ - if (!strcmp(insn->sec->name, ".init.text") && !module) + if (!strcmp(insn->sec->name, ".init.text") && !opts.module) continue; - WARN_FUNC("indirect %s found in RETPOLINE build", - insn->sec, insn->offset, - insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); + if (insn->type == INSN_RETURN) { + if (opts.rethunk) { + WARN_FUNC("'naked' return found in RETHUNK build", + insn->sec, insn->offset); + } else + continue; + } else { + WARN_FUNC("indirect %s found in RETPOLINE build", + insn->sec, insn->offset, + insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); + } warnings++; } @@ -2291,33 +3788,92 @@ static bool is_ubsan_insn(struct instruction *insn) "__ubsan_handle_builtin_unreachable")); } -static bool ignore_unreachable_insn(struct instruction *insn) +static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn) { int i; + struct instruction *prev_insn; - if (insn->ignore || insn->type == INSN_NOP) + if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP) return true; /* - * Ignore any unused exceptions. This can happen when a whitelisted - * function has an exception table entry. - * - * Also ignore alternative replacement instructions. This can happen + * Ignore alternative replacement instructions. This can happen * when a whitelisted function uses one of the ALTERNATIVE macros. */ - if (!strcmp(insn->sec->name, ".fixup") || - !strcmp(insn->sec->name, ".altinstr_replacement") || + if (!strcmp(insn->sec->name, ".altinstr_replacement") || !strcmp(insn->sec->name, ".altinstr_aux")) return true; /* + * Whole archive runs might encounter dead code from weak symbols. + * This is where the linker will have dropped the weak symbol in + * favour of a regular symbol, but leaves the code in place. + * + * In this case we'll find a piece of code (whole function) that is not + * covered by a !section symbol. Ignore them. + */ + if (opts.link && !insn->func) { + int size = find_symbol_hole_containing(insn->sec, insn->offset); + unsigned long end = insn->offset + size; + + if (!size) /* not a hole */ + return false; + + if (size < 0) /* hole until the end */ + return true; + + sec_for_each_insn_continue(file, insn) { + /* + * If we reach a visited instruction at or before the + * end of the hole, ignore the unreachable. + */ + if (insn->visited) + return true; + + if (insn->offset >= end) + break; + + /* + * If this hole jumps to a .cold function, mark it ignore too. + */ + if (insn->jump_dest && insn->jump_dest->func && + strstr(insn->jump_dest->func->name, ".cold")) { + struct instruction *dest = insn->jump_dest; + func_for_each_insn(file, dest->func, dest) + dest->ignore = true; + } + } + + return false; + } + + if (!insn->func) + return false; + + if (insn->func->static_call_tramp) + return true; + + /* + * CONFIG_UBSAN_TRAP inserts a UD2 when it sees + * __builtin_unreachable(). The BUG() macro has an unreachable() after + * the UD2, which causes GCC's undefined trap logic to emit another UD2 + * (or occasionally a JMP to UD2). + * + * It may also insert a UD2 after calling a __noreturn function. + */ + prev_insn = list_prev_entry(insn, list); + if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) && + (insn->type == INSN_BUG || + (insn->type == INSN_JUMP_UNCONDITIONAL && + insn->jump_dest && insn->jump_dest->type == INSN_BUG))) + return true; + + /* * Check if this (or a subsequent) instruction is related to * CONFIG_UBSAN or CONFIG_KASAN. * * End the search at 5 instructions to avoid going into the weeds. */ - if (!insn->func) - return false; for (i = 0; i < 5; i++) { if (is_kasan_insn(insn) || is_ubsan_insn(insn)) @@ -2342,157 +3898,446 @@ static bool ignore_unreachable_insn(struct instruction *insn) return false; } -static int validate_functions(struct objtool_file *file) +static int validate_symbol(struct objtool_file *file, struct section *sec, + struct symbol *sym, struct insn_state *state) { - struct section *sec; - struct symbol *func; struct instruction *insn; + int ret; + + if (!sym->len) { + WARN("%s() is missing an ELF size annotation", sym->name); + return 1; + } + + if (sym->pfunc != sym || sym->alias != sym) + return 0; + + insn = find_insn(file, sec, sym->offset); + if (!insn || insn->ignore || insn->visited) + return 0; + + state->uaccess = sym->uaccess_safe; + + ret = validate_branch(file, insn->func, insn, *state); + if (ret && opts.backtrace) + BT_FUNC("<=== (sym)", insn); + return ret; +} + +static int validate_section(struct objtool_file *file, struct section *sec) +{ struct insn_state state; - int ret, warnings = 0; + struct symbol *func; + int warnings = 0; - clear_insn_state(&state); + list_for_each_entry(func, &sec->symbol_list, list) { + if (func->type != STT_FUNC) + continue; - state.cfa = initial_func_cfi.cfa; - memcpy(&state.regs, &initial_func_cfi.regs, - CFI_NUM_REGS * sizeof(struct cfi_reg)); - state.stack_size = initial_func_cfi.cfa.offset; + init_insn_state(file, &state, sec); + set_func_state(&state.cfi); + + warnings += validate_symbol(file, sec, func, &state); + } + + return warnings; +} + +static int validate_noinstr_sections(struct objtool_file *file) +{ + struct section *sec; + int warnings = 0; + + sec = find_section_by_name(file->elf, ".noinstr.text"); + if (sec) { + warnings += validate_section(file, sec); + warnings += validate_unwind_hints(file, sec); + } + + sec = find_section_by_name(file->elf, ".entry.text"); + if (sec) { + warnings += validate_section(file, sec); + warnings += validate_unwind_hints(file, sec); + } + + return warnings; +} + +static int validate_functions(struct objtool_file *file) +{ + struct section *sec; + int warnings = 0; for_each_sec(file, sec) { - list_for_each_entry(func, &sec->symbol_list, list) { - if (func->type != STT_FUNC) - continue; + if (!(sec->sh.sh_flags & SHF_EXECINSTR)) + continue; - if (!func->len) { - WARN("%s() is missing an ELF size annotation", - func->name); - warnings++; - } + warnings += validate_section(file, sec); + } - if (func->pfunc != func || func->alias != func) - continue; + return warnings; +} - insn = find_insn(file, sec, func->offset); - if (!insn || insn->ignore || insn->visited) - continue; +static void mark_endbr_used(struct instruction *insn) +{ + if (!list_empty(&insn->call_node)) + list_del_init(&insn->call_node); +} - state.uaccess = func->uaccess_safe; +static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn) +{ + struct instruction *dest; + struct reloc *reloc; + unsigned long off; + int warnings = 0; - ret = validate_branch(file, func, insn, state); - if (ret && backtrace) - BT_FUNC("<=== (func)", insn); - warnings += ret; + /* + * Looking for function pointer load relocations. Ignore + * direct/indirect branches: + */ + switch (insn->type) { + case INSN_CALL: + case INSN_CALL_DYNAMIC: + case INSN_JUMP_CONDITIONAL: + case INSN_JUMP_UNCONDITIONAL: + case INSN_JUMP_DYNAMIC: + case INSN_JUMP_DYNAMIC_CONDITIONAL: + case INSN_RETURN: + case INSN_NOP: + return 0; + default: + break; + } + + for (reloc = insn_reloc(file, insn); + reloc; + reloc = find_reloc_by_dest_range(file->elf, insn->sec, + reloc->offset + 1, + (insn->offset + insn->len) - (reloc->offset + 1))) { + + /* + * static_call_update() references the trampoline, which + * doesn't have (or need) ENDBR. Skip warning in that case. + */ + if (reloc->sym->static_call_tramp) + continue; + + off = reloc->sym->offset; + if (reloc->type == R_X86_64_PC32 || reloc->type == R_X86_64_PLT32) + off += arch_dest_reloc_offset(reloc->addend); + else + off += reloc->addend; + + dest = find_insn(file, reloc->sym->sec, off); + if (!dest) + continue; + + if (dest->type == INSN_ENDBR) { + mark_endbr_used(dest); + continue; + } + + if (dest->func && dest->func == insn->func) { + /* + * Anything from->to self is either _THIS_IP_ or + * IRET-to-self. + * + * There is no sane way to annotate _THIS_IP_ since the + * compiler treats the relocation as a constant and is + * happy to fold in offsets, skewing any annotation we + * do, leading to vast amounts of false-positives. + * + * There's also compiler generated _THIS_IP_ through + * KCOV and such which we have no hope of annotating. + * + * As such, blanket accept self-references without + * issue. + */ + continue; } + + if (dest->noendbr) + continue; + + WARN_FUNC("relocation to !ENDBR: %s", + insn->sec, insn->offset, + offstr(dest->sec, dest->offset)); + + warnings++; } return warnings; } -static int validate_reachable_instructions(struct objtool_file *file) +static int validate_ibt_data_reloc(struct objtool_file *file, + struct reloc *reloc) { - struct instruction *insn; + struct instruction *dest; - if (file->ignore_unreachables) + dest = find_insn(file, reloc->sym->sec, + reloc->sym->offset + reloc->addend); + if (!dest) return 0; - for_each_insn(file, insn) { - if (insn->visited || ignore_unreachable_insn(insn)) + if (dest->type == INSN_ENDBR) { + mark_endbr_used(dest); + return 0; + } + + if (dest->noendbr) + return 0; + + WARN_FUNC("data relocation to !ENDBR: %s", + reloc->sec->base, reloc->offset, + offstr(dest->sec, dest->offset)); + + return 1; +} + +/* + * Validate IBT rules and remove used ENDBR instructions from the seal list. + * Unused ENDBR instructions will be annotated for sealing (i.e., replaced with + * NOPs) later, in create_ibt_endbr_seal_sections(). + */ +static int validate_ibt(struct objtool_file *file) +{ + struct section *sec; + struct reloc *reloc; + struct instruction *insn; + int warnings = 0; + + for_each_insn(file, insn) + warnings += validate_ibt_insn(file, insn); + + for_each_sec(file, sec) { + + /* Already done by validate_ibt_insn() */ + if (sec->sh.sh_flags & SHF_EXECINSTR) continue; - WARN_FUNC("unreachable instruction", insn->sec, insn->offset); - return 1; + if (!sec->reloc) + continue; + + /* + * These sections can reference text addresses, but not with + * the intent to indirect branch to them. + */ + if ((!strncmp(sec->name, ".discard", 8) && + strcmp(sec->name, ".discard.ibt_endbr_noseal")) || + !strncmp(sec->name, ".debug", 6) || + !strcmp(sec->name, ".altinstructions") || + !strcmp(sec->name, ".ibt_endbr_seal") || + !strcmp(sec->name, ".orc_unwind_ip") || + !strcmp(sec->name, ".parainstructions") || + !strcmp(sec->name, ".retpoline_sites") || + !strcmp(sec->name, ".smp_locks") || + !strcmp(sec->name, ".static_call_sites") || + !strcmp(sec->name, "_error_injection_whitelist") || + !strcmp(sec->name, "_kprobe_blacklist") || + !strcmp(sec->name, "__bug_table") || + !strcmp(sec->name, "__ex_table") || + !strcmp(sec->name, "__jump_table") || + !strcmp(sec->name, "__mcount_loc") || + !strcmp(sec->name, ".kcfi_traps") || + strstr(sec->name, "__patchable_function_entries")) + continue; + + list_for_each_entry(reloc, &sec->reloc->reloc_list, list) + warnings += validate_ibt_data_reloc(file, reloc); } - return 0; + return warnings; } -static void cleanup(struct objtool_file *file) +static int validate_sls(struct objtool_file *file) { - struct instruction *insn, *tmpinsn; - struct alternative *alt, *tmpalt; + struct instruction *insn, *next_insn; + int warnings = 0; + + for_each_insn(file, insn) { + next_insn = next_insn_same_sec(file, insn); + + if (insn->retpoline_safe) + continue; - list_for_each_entry_safe(insn, tmpinsn, &file->insn_list, list) { - list_for_each_entry_safe(alt, tmpalt, &insn->alts, list) { - list_del(&alt->list); - free(alt); + switch (insn->type) { + case INSN_RETURN: + if (!next_insn || next_insn->type != INSN_TRAP) { + WARN_FUNC("missing int3 after ret", + insn->sec, insn->offset); + warnings++; + } + + break; + case INSN_JUMP_DYNAMIC: + if (!next_insn || next_insn->type != INSN_TRAP) { + WARN_FUNC("missing int3 after indirect jump", + insn->sec, insn->offset); + warnings++; + } + break; + default: + break; } - list_del(&insn->list); - hash_del(&insn->hash); - free(insn); } - elf_close(file->elf); -} -static struct objtool_file file; + return warnings; +} -int check(const char *_objname, bool orc) +static int validate_reachable_instructions(struct objtool_file *file) { - int ret, warnings = 0; + struct instruction *insn; - objname = _objname; + if (file->ignore_unreachables) + return 0; + + for_each_insn(file, insn) { + if (insn->visited || ignore_unreachable_insn(file, insn)) + continue; - file.elf = elf_read(objname, orc ? O_RDWR : O_RDONLY); - if (!file.elf) + WARN_FUNC("unreachable instruction", insn->sec, insn->offset); return 1; + } + + return 0; +} - INIT_LIST_HEAD(&file.insn_list); - hash_init(file.insn_hash); - file.c_file = find_section_by_name(file.elf, ".comment"); - file.ignore_unreachables = no_unreachable; - file.hints = false; +int check(struct objtool_file *file) +{ + int ret, warnings = 0; arch_initial_func_cfi_state(&initial_func_cfi); + init_cfi_state(&init_cfi); + init_cfi_state(&func_cfi); + set_func_state(&func_cfi); + + if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3))) + goto out; - ret = decode_sections(&file); + cfi_hash_add(&init_cfi); + cfi_hash_add(&func_cfi); + + ret = decode_sections(file); if (ret < 0) goto out; + warnings += ret; - if (list_empty(&file.insn_list)) + if (list_empty(&file->insn_list)) goto out; - if (retpoline) { - ret = validate_retpoline(&file); + if (opts.retpoline) { + ret = validate_retpoline(file); if (ret < 0) return ret; warnings += ret; } - ret = validate_functions(&file); - if (ret < 0) - goto out; - warnings += ret; + if (opts.stackval || opts.orc || opts.uaccess) { + ret = validate_functions(file); + if (ret < 0) + goto out; + warnings += ret; - ret = validate_unwind_hints(&file); - if (ret < 0) - goto out; - warnings += ret; + ret = validate_unwind_hints(file, NULL); + if (ret < 0) + goto out; + warnings += ret; - if (!warnings) { - ret = validate_reachable_instructions(&file); + if (!warnings) { + ret = validate_reachable_instructions(file); + if (ret < 0) + goto out; + warnings += ret; + } + + } else if (opts.noinstr) { + ret = validate_noinstr_sections(file); if (ret < 0) goto out; warnings += ret; } - if (orc) { - ret = create_orc(&file); + if (opts.unret) { + /* + * Must be after validate_branch() and friends, it plays + * further games with insn->visited. + */ + ret = validate_unret(file); + if (ret < 0) + return ret; + warnings += ret; + } + + if (opts.ibt) { + ret = validate_ibt(file); if (ret < 0) goto out; + warnings += ret; + } - ret = create_orc_sections(&file); + if (opts.sls) { + ret = validate_sls(file); if (ret < 0) goto out; + warnings += ret; + } - ret = elf_write(file.elf); + if (opts.static_call) { + ret = create_static_call_sections(file); if (ret < 0) goto out; + warnings += ret; } -out: - cleanup(&file); + if (opts.retpoline) { + ret = create_retpoline_sites_sections(file); + if (ret < 0) + goto out; + warnings += ret; + } - /* ignore warnings for now until we get all the code cleaned up */ - if (ret || warnings) - return 0; + if (opts.rethunk) { + ret = create_return_sites_sections(file); + if (ret < 0) + goto out; + warnings += ret; + } + + if (opts.mcount) { + ret = create_mcount_loc_sections(file); + if (ret < 0) + goto out; + warnings += ret; + } + + if (opts.ibt) { + ret = create_ibt_endbr_seal_sections(file); + if (ret < 0) + goto out; + warnings += ret; + } + + if (opts.orc && !list_empty(&file->insn_list)) { + ret = orc_create(file); + if (ret < 0) + goto out; + warnings += ret; + } + + + if (opts.stats) { + printf("nr_insns_visited: %ld\n", nr_insns_visited); + printf("nr_cfi: %ld\n", nr_cfi); + printf("nr_cfi_reused: %ld\n", nr_cfi_reused); + printf("nr_cfi_cache: %ld\n", nr_cfi_cache); + } + +out: + /* + * For now, don't fail the kernel build on fatal warnings. These + * errors are still fairly common due to the growing matrix of + * supported toolchains and their recent pace of change. + */ return 0; } |