From: tip-bot for Wang Nan <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: wangnan0@huawei.com, lizefan@huawei.com,
masami.hiramatsu.pt@hitachi.com, mingo@kernel.org,
linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@zytor.com
Subject: [tip:perf/urgent] kprobes/x86: Mark 2 bytes NOP as boostable
Date: Wed, 18 Feb 2015 16:26:14 -0800 [thread overview]
Message-ID: <tip-b7e37567d080301d38a302bb93ba79d1ca446dca@git.kernel.org> (raw)
In-Reply-To: <1423532045-41049-1-git-send-email-wangnan0@huawei.com>
Commit-ID: b7e37567d080301d38a302bb93ba79d1ca446dca
Gitweb: http://git.kernel.org/tip/b7e37567d080301d38a302bb93ba79d1ca446dca
Author: Wang Nan <wangnan0@huawei.com>
AuthorDate: Tue, 10 Feb 2015 09:34:05 +0800
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 18 Feb 2015 21:50:12 +0100
kprobes/x86: Mark 2 bytes NOP as boostable
Currently, x86 kprobes is unable to boost 2 bytes nop like:
nopl 0x0(%rax,%rax,1)
which is 0x0f 0x1f 0x44 0x00 0x00.
Such nops have exactly 5 bytes 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>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1423532045-41049-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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 */
prev parent reply other threads:[~2015-02-19 0:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-09 12:45 [PATCH] kprobes: x86: mark 2 bytes NOP as boostable Wang Nan
2015-02-09 23:34 ` Masami Hiramatsu
2015-02-10 1:34 ` [PATCH][RESEND] " Wang Nan
2015-02-11 4:18 ` Wang Nan
2015-02-19 0:26 ` tip-bot for Wang Nan [this message]
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