linux-kernel - Re: [PATCH v5 07/10] x86/asm/acpi: Fix asmvalidate warnings for wakeup

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Message-ID: <20150611123654.GA24528@amd>
Date:	Thu, 11 Jun 2015 14:36:54 +0200
From:	Pavel Machek <pavel@....cz>
To:	Josh Poimboeuf <jpoimboe@...hat.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Michal Marek <mmarek@...e.cz>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>, x86@...nel.org,
	live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>, linux-pm@...r.kernel.org
Subject: Re: [PATCH v5 07/10] x86/asm/acpi: Fix asmvalidate warnings for
 wakeup_64.S

Hi!

> > > 5. Remove superfluous rsp changes.
> > 
> > Did you test the changes?
> 
> Yes, I verified that it didn't break suspend/resume on my system.

Ok, so I can not see anything wrong, either. I'd like to understand
why the original code manipulated %rsp, but...

If you did testing with frame pointer on, you can get my

Acked-by: Pavel Machek <pavel@....cz>

> > Do you plan to make similar changes to wakeup_32.S?
> 
> Currently, asmvalidate is x86_64 only, so I'm only fixing the 64-bit
> stuff right now.

Well, you are "improving debuggability", afaict. It worked well before.

> > > @@ -108,8 +108,9 @@ ENTRY(do_suspend_lowlevel)
> > >  	movq	pt_regs_r15(%rax), %r15
> > >  
> > >  	xorl	%eax, %eax
> > > -	addq	$8, %rsp
> > > -	jmp	restore_processor_state
> > > +	call	restore_processor_state
> > > +	FP_RESTORE
> > > +	ret
> > >  ENDPROC(do_suspend_lowlevel)
> > 
> > Umm. I rather liked the direct jump.
> 
> Why?

It is both smaller and faster than the new code. But...

									Pavel

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