The following commit has been merged into the objtool/core branch of tip: Commit-ID: 2ee0c363492f1acc1082125218e6a80c0d7d502b Gitweb: https://git.kernel.org/tip/2ee0c363492f1acc1082125218e6a80c0d7d502b Author: Peter Zijlstra <pet...@infradead.org> AuthorDate: Tue, 09 Feb 2021 21:29:16 +01:00 Committer: Ingo Molnar <mi...@kernel.org> CommitterDate: Sat, 06 Mar 2021 12:44:23 +01:00
objtool,x86: Rewrite LEA decode Current LEA decoding is a bunch of special cases, properly decode the instruction, with exception of full SIB and RIP-relative modes. Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Signed-off-by: Ingo Molnar <mi...@kernel.org> Acked-by: Josh Poimboeuf <jpoim...@redhat.com> Tested-by: Nick Desaulniers <ndesaulni...@google.com> Link: https://lkml.kernel.org/r/20210211173627.143250...@infradead.org --- tools/objtool/arch/x86/decode.c | 86 ++++++++++---------------------- 1 file changed, 28 insertions(+), 58 deletions(-) diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index 549813c..d8f0138 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -91,9 +91,10 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, { struct insn insn; int x86_64, sign; - unsigned char op1, op2, rex = 0, rex_b = 0, rex_r = 0, rex_w = 0, - rex_x = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0, - modrm_reg = 0, sib = 0; + unsigned char op1, op2, + rex = 0, rex_b = 0, rex_r = 0, rex_w = 0, rex_x = 0, + modrm = 0, modrm_mod = 0, modrm_rm = 0, modrm_reg = 0, + sib = 0; struct stack_op *op = NULL; struct symbol *sym; @@ -328,68 +329,37 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, break; case 0x8d: - if (sib == 0x24 && rex_w && !rex_b && !rex_x) { - - ADD_OP(op) { - if (!insn.displacement.value) { - /* lea (%rsp), reg */ - op->src.type = OP_SRC_REG; - } else { - /* lea disp(%rsp), reg */ - op->src.type = OP_SRC_ADD; - op->src.offset = insn.displacement.value; - } - op->src.reg = CFI_SP; - op->dest.type = OP_DEST_REG; - op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r]; - } - - } else if (rex == 0x48 && modrm == 0x65) { - - /* lea disp(%rbp), %rsp */ - ADD_OP(op) { - op->src.type = OP_SRC_ADD; - op->src.reg = CFI_BP; - op->src.offset = insn.displacement.value; - op->dest.type = OP_DEST_REG; - op->dest.reg = CFI_SP; - } + if (modrm_mod == 3) { + WARN("invalid LEA encoding at %s:0x%lx", sec->name, offset); + break; + } - } else if (rex == 0x49 && modrm == 0x62 && - insn.displacement.value == -8) { + /* skip non 64bit ops */ + if (!rex_w) + break; - /* - * lea -0x8(%r10), %rsp - * - * Restoring rsp back to its original value after a - * stack realignment. - */ - ADD_OP(op) { - op->src.type = OP_SRC_ADD; - op->src.reg = CFI_R10; - op->src.offset = -8; - op->dest.type = OP_DEST_REG; - op->dest.reg = CFI_SP; - } + /* skip nontrivial SIB */ + if (modrm_rm == 4 && !(sib == 0x24 && rex_b == rex_x)) + break; - } else if (rex == 0x49 && modrm == 0x65 && - insn.displacement.value == -16) { + /* skip RIP relative displacement */ + if (modrm_rm == 5 && modrm_mod == 0) + break; - /* - * lea -0x10(%r13), %rsp - * - * Restoring rsp back to its original value after a - * stack realignment. - */ - ADD_OP(op) { + /* lea disp(%src), %dst */ + ADD_OP(op) { + op->src.offset = insn.displacement.value; + if (!op->src.offset) { + /* lea (%src), %dst */ + op->src.type = OP_SRC_REG; + } else { + /* lea disp(%src), %dst */ op->src.type = OP_SRC_ADD; - op->src.reg = CFI_R13; - op->src.offset = -16; - op->dest.type = OP_DEST_REG; - op->dest.reg = CFI_SP; } + op->src.reg = op_to_cfi_reg[modrm_rm][rex_b]; + op->dest.type = OP_DEST_REG; + op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r]; } - break; case 0x8f:
