Re: [patch] i386, vdso=[0|1] boot option and /proc/sys/vm/vdso_enabled

Zachary Amsden
2006-05-20T09:34:54Z

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Andrew Morton wrote:
> vmm:/home/akpm# echo 1 > /proc/sys/vm/vdso_enabled
> vmm:/home/akpm#
> vmm:/home/akpm> ls -l
> zsh: segmentation fault ls -l
>
>
>> That could tell us whether
>> it's an init bug or a glibc bug.
>>
>
> It tells us neither. This could be a new kernel bug which only certain old
> userspace setups are known to trigger. Until we know exactly why this is
> occurring, we don't know where the bug is.
>
> And once we've worked that thing out, and if we determine that the bug is
> in userspace then we might be able to craft the patch in such a fashion
> that the old userspace continues to work, which would be a win.
>

Please try my patch - sent earlier, but attached again. It will tell
you with 100% confidence if the problem is with userspace expecting the
vsyscall page to be at a particular address.

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Index: linux-2.6.17-rc/include/asm-i386/fixmap.h
===================================================================
--- linux-2.6.17-rc.orig/include/asm-i386/fixmap.h 2006-03-19 21:53:29.000000000 -0800
+++ linux-2.6.17-rc/include/asm-i386/fixmap.h 2006-05-19 18:16:00.000000000 -0700
@@ -20,7 +20,7 @@
* Leave one empty page between vmalloc'ed areas and
* the start of the fixmap.
*/
-#define __FIXADDR_TOP 0xfffff000
+#define __FIXADDR_TOP 0xffbff000

#ifndef __ASSEMBLY__
#include <linux/kernel.h>