From 627fce14809ba5610b0cb476cd0186d3fcedecfc Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Tue, 11 Jul 2017 10:33:42 -0500 Subject: objtool: Add ORC unwind table generation Now that objtool knows the states of all registers on the stack for each instruction, it's straightforward to generate debuginfo for an unwinder to use. Instead of generating DWARF, generate a new format called ORC, which is more suitable for an in-kernel unwinder. See Documentation/x86/orc-unwinder.txt for a more detailed description of this new debuginfo format and why it's preferable to DWARF. Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jiri Slaby Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/c9b9f01ba6c5ed2bdc9bb0957b78167fdbf9632e.1499786555.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- tools/objtool/check.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 54 insertions(+), 4 deletions(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 2c6d74880403..cb57c526ba17 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -36,8 +36,8 @@ const char *objname; static bool nofp; struct cfi_state initial_func_cfi; -static struct instruction *find_insn(struct objtool_file *file, - struct section *sec, unsigned long offset) +struct instruction *find_insn(struct objtool_file *file, + struct section *sec, unsigned long offset) { struct instruction *insn; @@ -259,6 +259,11 @@ static int decode_instructions(struct objtool_file *file) if (!(sec->sh.sh_flags & SHF_EXECINSTR)) continue; + if (strcmp(sec->name, ".altinstr_replacement") && + strcmp(sec->name, ".altinstr_aux") && + strncmp(sec->name, ".discard.", 9)) + sec->text = true; + for (offset = 0; offset < sec->len; offset += insn->len) { insn = malloc(sizeof(*insn)); if (!insn) { @@ -947,6 +952,30 @@ static bool has_valid_stack_frame(struct insn_state *state) return false; } +static int update_insn_state_regs(struct instruction *insn, struct insn_state *state) +{ + struct cfi_reg *cfa = &state->cfa; + struct stack_op *op = &insn->stack_op; + + if (cfa->base != CFI_SP) + return 0; + + /* push */ + if (op->dest.type == OP_DEST_PUSH) + cfa->offset += 8; + + /* pop */ + if (op->src.type == OP_SRC_POP) + cfa->offset -= 8; + + /* add immediate to sp */ + if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD && + op->dest.reg == CFI_SP && op->src.reg == CFI_SP) + cfa->offset -= op->src.offset; + + return 0; +} + static void save_reg(struct insn_state *state, unsigned char reg, int base, int offset) { @@ -1032,6 +1061,9 @@ 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); + switch (op->dest.type) { case OP_DEST_REG: @@ -1323,6 +1355,10 @@ static bool insn_state_match(struct instruction *insn, struct insn_state *state) break; } + } else if (state1->type != state2->type) { + WARN_FUNC("stack state mismatch: type1=%d type2=%d", + insn->sec, insn->offset, state1->type, state2->type); + } else if (state1->drap != state2->drap || (state1->drap && state1->drap_reg != state2->drap_reg)) { WARN_FUNC("stack state mismatch: drap1=%d(%d) drap2=%d(%d)", @@ -1613,7 +1649,7 @@ static void cleanup(struct objtool_file *file) elf_close(file->elf); } -int check(const char *_objname, bool _nofp) +int check(const char *_objname, bool _nofp, bool orc) { struct objtool_file file; int ret, warnings = 0; @@ -1621,7 +1657,7 @@ int check(const char *_objname, bool _nofp) objname = _objname; nofp = _nofp; - file.elf = elf_open(objname); + file.elf = elf_open(objname, orc ? O_RDWR : O_RDONLY); if (!file.elf) return 1; @@ -1654,6 +1690,20 @@ int check(const char *_objname, bool _nofp) warnings += ret; } + if (orc) { + ret = create_orc(&file); + if (ret < 0) + goto out; + + ret = create_orc_sections(&file); + if (ret < 0) + goto out; + + ret = elf_write(file.elf); + if (ret < 0) + goto out; + } + out: cleanup(&file); -- cgit v1.2.3-59-g8ed1b