From b490f45362002fef57996388e395efc974b013f4 Mon Sep 17 00:00:00 2001 From: Miroslav Benes Date: Fri, 24 Apr 2020 16:30:42 +0200 Subject: objtool: Move the IRET hack into the arch decoder Quoting Julien: "And the other suggestion is my other email was that you don't even need to add INSN_EXCEPTION_RETURN. You can keep IRET as INSN_CONTEXT_SWITCH by default and x86 decoder lookups the symbol conaining an iret. If it's a function symbol, it can just set the type to INSN_OTHER so that it caries on to the next instruction after having handled the stack_op." Suggested-by: Julien Thierry Signed-off-by: Miroslav Benes Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200428191659.913283807@infradead.org --- tools/objtool/arch/x86/decode.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-) (limited to 'tools/objtool/arch/x86/decode.c') diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index e26bedbfff95..d7b5d1096913 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -94,6 +94,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, rex_x = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0, modrm_reg = 0, sib = 0; struct stack_op *op = NULL; + struct symbol *sym; x86_64 = is_x86_64(elf); if (x86_64 == -1) @@ -469,17 +470,24 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, break; case 0xcf: /* iret */ - *type = INSN_EXCEPTION_RETURN; - - ADD_OP(op) { - /* add $40, %rsp */ - op->src.type = OP_SRC_ADD; - op->src.reg = CFI_SP; - op->src.offset = 5*8; - op->dest.type = OP_DEST_REG; - op->dest.reg = CFI_SP; + /* + * Handle sync_core(), which has an IRET to self. + * All other IRET are in STT_NONE entry code. + */ + sym = find_symbol_containing(sec, offset); + if (sym && sym->type == STT_FUNC) { + ADD_OP(op) { + /* add $40, %rsp */ + op->src.type = OP_SRC_ADD; + op->src.reg = CFI_SP; + op->src.offset = 5*8; + op->dest.type = OP_DEST_REG; + op->dest.reg = CFI_SP; + } + break; } - break; + + /* fallthrough */ case 0xca: /* retf */ case 0xcb: /* retf */ -- cgit v1.2.3