linux-kernel - Re: [PATCH 2/2] x86: ia32_signal: remove unnecessary padding

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Message-ID: <20081112112937.GA6372@elte.hu>
Date:	Wed, 12 Nov 2008 12:29:37 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86: ia32_signal: remove unnecessary padding


* Hiroshi Shimamoto <h-shimamoto@...jp.nec.com> wrote:

> From: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
> 
> Impact: cleanup
> 
> Remove unnecessary paddings, this saves 4 bytes.
> 
> Signed-off-by: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
> ---
>  arch/x86/ia32/ia32_signal.c |    5 +----
>  1 files changed, 1 insertions(+), 4 deletions(-)

applied your patches to tip/x86/signal:

 9cc3c49: x86: ia32_signal: remove unnecessary padding
 4a61204: x86: signal_32: introduce retcode and rt_retcode

thanks!

A question - this change:

> @@ -427,12 +427,10 @@ int ia32_setup_frame(int sig, struct k_sigaction *ka,
>  		u16 poplmovl;
>  		u32 val;
>  		u16 int80;
> -		u16 pad;
>  	} __attribute__((packed)) code = {
>  		0xb858,		 /* popl %eax ; movl $...,%eax */
>  		__NR_ia32_sigreturn,
>  		0x80cd,		/* int $0x80 */
> -		0,
>  	};
>  
>  	frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
> @@ -508,8 +506,7 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
>  		u8 movl;
>  		u32 val;
>  		u16 int80;
> -		u16 pad;
> -		u8  pad2;
> +		u8  pad;
>  	} __attribute__((packed)) code = {
>  		0xb8,
>  		__NR_ia32_rt_sigreturn,

does not impact any ABI, because it's only about the signal trampoline 
the kernel pushes to the user-space stack - not about any 
userspace-visible signal frame detail, right?

	Ingo
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