linux-kernel - [PATCH] objtool: fix bytes check of lea's rex

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Date:   Mon,  5 Dec 2016 11:55:51 +0100
From:   Jiri Slaby <jslaby@...e.cz>
To:     mingo@...nel.org
Cc:     linux-kernel@...r.kernel.org, Jiri Slaby <jslaby@...e.cz>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: [PATCH] objtool: fix bytes check of lea's rex_prefix

For the "lea %(rsp), %rbp" case, we check if there is a rex_prefix. But
we check "bytes" which is insn_byte_t[4] in rex_prefix (insn_field
structure). Therefore, the check is always true.

Instead, check nbytes which is the right one.

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
---
 tools/objtool/arch/x86/decode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index b63a31be1218..5e0dea2cdc01 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -99,7 +99,7 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
 		break;
 
 	case 0x8d:
-		if (insn.rex_prefix.bytes &&
+		if (insn.rex_prefix.nbytes &&
 		    insn.rex_prefix.bytes[0] == 0x48 &&
 		    insn.modrm.nbytes && insn.modrm.bytes[0] == 0x2c &&
 		    insn.sib.nbytes && insn.sib.bytes[0] == 0x24)
-- 
2.11.0