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Commit b7e37567 authored by Wang Nan's avatar Wang Nan Committed by Ingo Molnar
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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: default avatarWang Nan <wangnan0@huawei.com>
Acked-by: default avatarMasami 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: default avatarIngo Molnar <mingo@kernel.org>
parent 5154d4f2

arch/x86/kernel/kprobes/core.c

+1 −1
Original line number Diff line number Diff line
@@ -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 */