linux-kernel - Re: [PATCH] i386/audit: stop scribbling on the stack frame

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Date:	Mon, 27 Oct 2014 10:02:05 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Eric Paris <eparis@...hat.com>, Richard Guy Briggs <rgb@...hat.com>
CC:	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
	przanoni@...il.com, mingo@...nel.org, hpa@...ux.intel.com,
	linux-tip-commits@...r.kernel.org, linux-audit@...hat.com
Subject: Re: [PATCH] i386/audit: stop scribbling on the stack frame

On 10/27/2014 06:55 AM, Eric Paris wrote:
> My patch was already committed to the -tip urgent branch.  I believe any
> optimization should be based on that branch, Richard.  If you are trying
> to wrangle every bit of speed out of this, should you
> 
> push %esi;
> push %edi;
> CFI_ADJUST_CFA_OFFSET 8
> call __audit_syscall_entry
> pop;
> pop;
> CFI_ADJUST_CFA_OFFSET -8
> 
> Instead of using the pushl_cfi and popl_cfi macros?
> 
> I wrote my patch to be obviously correct, but agree there are certainly
> some speedups possible.
> 

Uh... not only is that plain wrong (the CFI should be adjusted after
each instruction that changes the stack pointer), but what the heck is
wrong with using the macros?

	-hpa



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