From: Wang Nan Date: Tue, 10 Feb 2015 01:34:05 +0000 (+0800) Subject: kprobes/x86: Mark 2 bytes NOP as boostable X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=b7e37567d080301d38a302bb93ba79d1ca446dca;p=openwrt%2Fstaging%2Fblogic.git 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 Acked-by: Masami Hiramatsu Cc: Link: http://lkml.kernel.org/r/1423532045-41049-1-git-send-email-wangnan0@huawei.com Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 98f654d466e5..6a1146ea4d4d 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 */