linux-kernel - Re: [PATCH] x86: pad assembly functions with INT3

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Date:   Mon, 07 May 2018 14:41:14 -0700
From:   hpa@...or.com
To:     Alexey Dobriyan <adobriyan@...il.com>, tglx@...utronix.de,
        mingo@...hat.com
CC:     linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH] x86: pad assembly functions with INT3

On May 7, 2018 2:37:55 PM PDT, Alexey Dobriyan <adobriyan@...il.com> wrote:
>Use INT3 instead of NOP. All that padding between functions is
>an illegal area, no legitimate code should jump into it.
>
>I've checked x86_64 allyesconfig disassembly, all changes looks sane:
>INT3 is only used after RET or unconditional JMP.
>
>Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
>---
>
> arch/x86/include/asm/linkage.h |    2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>--- a/arch/x86/include/asm/linkage.h
>+++ b/arch/x86/include/asm/linkage.h
>@@ -18,7 +18,7 @@
> 	name:
> 
> #if defined(CONFIG_X86_64) || defined(CONFIG_X86_ALIGNMENT_16)
>-#define __ALIGN		.p2align 4, 0x90
>+#define __ALIGN		.p2align 4, 0xCC
> #define __ALIGN_STR	__stringify(__ALIGN)
> #endif
> 

Acked-by: H. Peter Anvin <h.peter.anvin@in tel.com>
-- 
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