diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/s390/kernel/ftrace.c | 105 |
1 files changed, 68 insertions, 37 deletions
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c index 21d62d8b6b9a..416b5a94353d 100644 --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -4,8 +4,7 @@ * * Copyright IBM Corp. 2009,2014 * - * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>, - * Martin Schwidefsky <schwidefsky@de.ibm.com> + * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> */ #include <linux/moduleloader.h> @@ -61,18 +60,9 @@ asm( #ifdef CONFIG_EXPOLINE asm( " .align 16\n" - "ftrace_shared_hotpatch_trampoline_ex:\n" - " lmg %r0,%r1,2(%r1)\n" - " ex %r0," __stringify(__LC_BR_R1) "(%r0)\n" - " j .\n" - "ftrace_shared_hotpatch_trampoline_ex_end:\n" -); - -asm( - " .align 16\n" "ftrace_shared_hotpatch_trampoline_exrl:\n" " lmg %r0,%r1,2(%r1)\n" - " .insn ril,0xc60000000000,%r0,0f\n" /* exrl */ + " exrl %r0,0f\n" " j .\n" "0: br %r1\n" "ftrace_shared_hotpatch_trampoline_exrl_end:\n" @@ -91,12 +81,8 @@ static const char *ftrace_shared_hotpatch_trampoline(const char **end) tend = ftrace_shared_hotpatch_trampoline_br_end; #ifdef CONFIG_EXPOLINE if (!nospec_disable) { - tstart = ftrace_shared_hotpatch_trampoline_ex; - tend = ftrace_shared_hotpatch_trampoline_ex_end; - if (test_facility(35)) { /* exrl */ - tstart = ftrace_shared_hotpatch_trampoline_exrl; - tend = ftrace_shared_hotpatch_trampoline_exrl_end; - } + tstart = ftrace_shared_hotpatch_trampoline_exrl; + tend = ftrace_shared_hotpatch_trampoline_exrl_end; } #endif /* CONFIG_EXPOLINE */ if (end) @@ -159,37 +145,73 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) return 0; } +static struct ftrace_hotpatch_trampoline *ftrace_get_trampoline(struct dyn_ftrace *rec) +{ + struct ftrace_hotpatch_trampoline *trampoline; + struct ftrace_insn insn; + s64 disp; + u16 opc; + + if (copy_from_kernel_nofault(&insn, (void *)rec->ip, sizeof(insn))) + return ERR_PTR(-EFAULT); + disp = (s64)insn.disp * 2; + trampoline = (void *)(rec->ip + disp); + if (get_kernel_nofault(opc, &trampoline->brasl_opc)) + return ERR_PTR(-EFAULT); + if (opc != 0xc015) + return ERR_PTR(-EINVAL); + return trampoline; +} + int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr) { + struct ftrace_hotpatch_trampoline *trampoline; + u64 old; + + trampoline = ftrace_get_trampoline(rec); + if (IS_ERR(trampoline)) + return PTR_ERR(trampoline); + if (get_kernel_nofault(old, &trampoline->interceptor)) + return -EFAULT; + if (old != old_addr) + return -EINVAL; + s390_kernel_write(&trampoline->interceptor, &addr, sizeof(addr)); return 0; } -static void brcl_disable(void *brcl) +static int ftrace_patch_branch_mask(void *addr, u16 expected, bool enable) { - u8 op = 0x04; /* set mask field to zero */ + u16 old; + u8 op; - s390_kernel_write((char *)brcl + 1, &op, sizeof(op)); + if (get_kernel_nofault(old, addr)) + return -EFAULT; + if (old != expected) + return -EINVAL; + /* set mask field to all ones or zeroes */ + op = enable ? 0xf4 : 0x04; + s390_kernel_write((char *)addr + 1, &op, sizeof(op)); + return 0; } int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { - brcl_disable((void *)rec->ip); - return 0; -} - -static void brcl_enable(void *brcl) -{ - u8 op = 0xf4; /* set mask field to all ones */ - - s390_kernel_write((char *)brcl + 1, &op, sizeof(op)); + /* Expect brcl 0xf,... */ + return ftrace_patch_branch_mask((void *)rec->ip, 0xc0f4, false); } int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { - brcl_enable((void *)rec->ip); - return 0; + struct ftrace_hotpatch_trampoline *trampoline; + + trampoline = ftrace_get_trampoline(rec); + if (IS_ERR(trampoline)) + return PTR_ERR(trampoline); + s390_kernel_write(&trampoline->interceptor, &addr, sizeof(addr)); + /* Expect brcl 0x0,... */ + return ftrace_patch_branch_mask((void *)rec->ip, 0xc004, true); } int ftrace_update_ftrace_func(ftrace_func_t func) @@ -203,14 +225,13 @@ void arch_ftrace_update_code(int command) ftrace_modify_all_code(command); } -int ftrace_arch_code_modify_post_process(void) +void ftrace_arch_code_modify_post_process(void) { /* * Flush any pre-fetched instructions on all * CPUs to make the new code visible. */ text_poke_sync_lock(); - return 0; } #ifdef CONFIG_MODULES @@ -262,14 +283,24 @@ NOKPROBE_SYMBOL(prepare_ftrace_return); */ int ftrace_enable_ftrace_graph_caller(void) { - brcl_disable(ftrace_graph_caller); + int rc; + + /* Expect brc 0xf,... */ + rc = ftrace_patch_branch_mask(ftrace_graph_caller, 0xa7f4, false); + if (rc) + return rc; text_poke_sync_lock(); return 0; } int ftrace_disable_ftrace_graph_caller(void) { - brcl_enable(ftrace_graph_caller); + int rc; + + /* Expect brc 0x0,... */ + rc = ftrace_patch_branch_mask(ftrace_graph_caller, 0xa704, true); + if (rc) + return rc; text_poke_sync_lock(); return 0; } @@ -291,7 +322,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, regs = ftrace_get_regs(fregs); p = get_kprobe((kprobe_opcode_t *)ip); - if (unlikely(!p) || kprobe_disabled(p)) + if (!regs || unlikely(!p) || kprobe_disabled(p)) goto out; if (kprobe_running()) { |