linux-kernel - Re: [PATCH 2/5] x86: ret_from_fork

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Message-ID: <874p1u45ke.fsf@basil.nowhere.org>
Date:	Wed, 26 Nov 2008 21:04:33 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	gorcunov@...il.com
Cc:	mingo@...e.hu, tglx@...utronix.de, hpa@...or.com,
	linux-kernel@...r.kernel.org, heukelum@...tmail.fm
Subject: Re: [PATCH 2/5] x86: ret_from_fork - get rid of jump back

gorcunov@...il.com writes:
> --- a/arch/x86/kernel/entry_64.S
> +++ b/arch/x86/kernel/entry_64.S
> @@ -379,7 +379,10 @@ ENTRY(ret_from_fork)
>  	GET_THREAD_INFO(%rcx)
>  	testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),TI_flags(%rcx)
>  	CFI_REMEMBER_STATE
> -	jnz rff_trace
> +	jz rff_action
> +	movq %rsp,%rdi
> +	call syscall_trace_leave
> +	GET_THREAD_INFO(%rcx)

The uncommon path is supposed to be out of line. I don't think
the CPU will like that.

-Andi

>  rff_action:

-- 
ak@...ux.intel.com
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