linux-kernel - Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending

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Date:	Fri, 29 Feb 2008 22:26:54 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	"Klaus S. Madsen" <ksm@...rnemadsen.org>,
	LKML <linux-kernel@...r.kernel.org>, Pavel Machek <pavel@....cz>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending


* H. Peter Anvin <hpa@...or.com> wrote:

> Klaus S. Madsen wrote:
>> open("/dev/mem", O_RDWR)                = 5
>> mmap2(NULL, 1282, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_SHARED|MAP_FIXED, 5, 0) = 0
>> mmap2(0xa0000, 393216, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, 5, 0xa0) = 0xa0000
>                          ^^^^^^^^^^^^^^^^^^^^
>> close(5)                                = 0
>> ioperm(0, 0x400, 0x1)                   = 0
>> iopl(0x3)                               = 0
>> access("/sys/bus/pci", R_OK)            = 0
>> write(1, "Calling get_mode\n", 17)      = 17
>> vm86(0x1, 0xb7f14ccc, 0xb7f14830, 0xc000, 0x18b6 <unfinished ...>
>> --- SIGSEGV (Segmentation fault) @ 0 (0) ---
>> +++ killed by SIGSEGV (core dumped) +++
>
> This is the VGA BIOS being mapped, it's mapped PROT_READ|PROT_WRITE, but  
> no PROT_EXEC; if the kernel is NX-capable it *should* segfault trying to 
> execute out of this area, which is exactly what will happen when vm86 
> executes INT 10h.
>
> If we can find that mmap() in the s2ram source code and add PROT_EXEC 
> to it, it would be interesting.

Klaus, could you send your .config as well? Lets make sure that NX is 
even relevant in this context.

	Ingo
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