linux-kernel - Re: [PATCH -tip] x86: acpi/sleep.c saved

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Message-ID: <20090410181109.GC25317@elf.ucw.cz>
Date:	Fri, 10 Apr 2009 20:11:09 +0200
From:	Pavel Machek <pavel@....cz>
To:	Jaswinder Singh Rajput <jaswinder@...nel.org>
Cc:	Ingo Molnar <mingo@...e.hu>, x86 maintainers <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -tip] x86: acpi/sleep.c saved_magic fix overflow

On Fri 2009-04-10 23:35:29, Jaswinder Singh Rajput wrote:
> On Fri, 2009-04-10 at 19:55 +0200, Pavel Machek wrote:
> > On Fri 2009-04-10 23:06:55, Jaswinder Singh Rajput wrote:
> > > Impact: fix overflow
> > 
> > > Constant 0x123456789abcdef0 is so big for a long.
> > > So using saved_magic 0x12345678 for both 32 and 64 bit.
> > 
> > Have you tested the patch? I have feeling that this is tested from
> > assembly... Plus it is only set to long constant on 64-bit, so I don't
> > think you are fixing anything. And if your code is correct the
> > variable is write only...
> > 
> 
> I have tested this:
> 1.  CHECK   arch/x86/kernel/acpi/sleep.c
> arch/x86/kernel/acpi/sleep.c:107:16: warning: constant 0x123456789abcdef0 is so big it is long
> 
> 2. On 64 bit machine box:
> 	long l1;
> 
> 	l1 = 0x123456789abcdef0;
> 	printf("0x%16x : ", l1);
> 
> Output: 0x        9abcdef0

I don't have 64-bit box handy, but please make sure that
suspend/resume works before and after your change.

If the variable is _not_ tested from assembly, just remove
saved_magic...

								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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