From: Wang Nan <wangnan0@huawei.com>
To: <masami.hiramatsu.pt@hitachi.com>, <tglx@linutronix.de>,
<mingo@redhat.com>, <x86@kernel.org>
Cc: <linux-kernel@vger.kernel.org>, <lizefan@huawei.com>
Subject: [PATCH] kprobes: x86: mark 2 bytes NOP as boostable.
Date: Mon, 9 Feb 2015 20:45:06 +0800 [thread overview]
Message-ID: <1423485906-76291-1-git-send-email-wangnan0@huawei.com> (raw)
x86 kprobes is unable to probe at 2 bytes nop like:
nopl 0x0(%rax,%rax,1)
which is 0x0f 0x1f 0x44 0x00 0x00.
Such nops have exactly 5 bytes which is able to hold a relative jmp
instruction. Boosting them should be obviously safe.
This patch enable boosting such nops by simply updating
twobyte_is_boostable[] array.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
arch/x86/kernel/kprobes/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 98f654d..6a1146e 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -84,7 +84,7 @@ static volatile u32 twobyte_is_boostable[256 / 32] = {
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
/* ---------------------------------------------- */
W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */
- W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 10 */
+ W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1) , /* 10 */
W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */
W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */
W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
--
1.8.4
next reply other threads:[~2015-02-09 12:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-09 12:45 Wang Nan [this message]
2015-02-09 23:34 ` [PATCH] kprobes: x86: mark 2 bytes NOP as boostable Masami Hiramatsu
2015-02-10 1:34 ` [PATCH][RESEND] " Wang Nan
2015-02-11 4:18 ` Wang Nan
2015-02-19 0:26 ` [tip:perf/urgent] kprobes/x86: Mark " tip-bot for Wang Nan
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