* [PATCH] fix kexec asm
@ 2006-03-08 2:35 Chris Mason
2006-03-08 4:16 ` Eric W. Biederman
0 siblings, 1 reply; 3+ messages in thread
From: Chris Mason @ 2006-03-08 2:35 UTC (permalink / raw
To: linux-kernel, akpm, mmlnx, Eric W. Biederman
From: Michael Matz <matz@suse.de>
While testing kexec and kdump we hit problems where the new kernel would
freeze or instantly reboot. The easiest way to trigger it was to kexec a
kernel compiled for CONFIG_M586 on an athlon cpu. Compiling
for CONFIG_MK7 instead would work fine.
The patch below fixes a few problems with the kexec inline asm.
Signed-off-by: Chris Mason <mason@suse.com>
---
diff -urp linux-2.6.15.suse/arch/i386/kernel/machine_kexec.c linux-2.6.15/arch/i386/kernel/machine_kexec.c
--- linux-2.6.15.suse/arch/i386/kernel/machine_kexec.c 2006-01-03 04:21:10.000000000 +0100
+++ linux-2.6.15/arch/i386/kernel/machine_kexec.c 2006-02-08 04:19:13.000000000 +0100
@@ -116,13 +116,13 @@ static void load_segments(void)
__asm__ __volatile__ (
"\tljmp $"STR(__KERNEL_CS)",$1f\n"
"\t1:\n"
- "\tmovl $"STR(__KERNEL_DS)",%eax\n"
- "\tmovl %eax,%ds\n"
- "\tmovl %eax,%es\n"
- "\tmovl %eax,%fs\n"
- "\tmovl %eax,%gs\n"
- "\tmovl %eax,%ss\n"
- );
+ "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
+ "\tmovl %%eax,%%ds\n"
+ "\tmovl %%eax,%%es\n"
+ "\tmovl %%eax,%%fs\n"
+ "\tmovl %%eax,%%gs\n"
+ "\tmovl %%eax,%%ss\n"
+ ::: "eax", "memory");
#undef STR
#undef __STR
}
diff -urp linux-2.6.15.suse/arch/x86_64/kernel/machine_kexec.c linux-2.6.15/arch/x86_64/kernel/machine_kexec.c
--- linux-2.6.15.suse/arch/x86_64/kernel/machine_kexec.c 2006-01-03 04:21:10.000000000 +0100
+++ linux-2.6.15/arch/x86_64/kernel/machine_kexec.c 2006-02-08 04:21:13.000000000 +0100
@@ -140,7 +140,7 @@ static void load_segments(void)
"\tmovl %0,%%ss\n"
"\tmovl %0,%%fs\n"
"\tmovl %0,%%gs\n"
- : : "a" (__KERNEL_DS)
+ : : "a" (__KERNEL_DS) : "memory"
);
}
diff -urp linux-2.6.15.suse/include/asm-powerpc/kexec.h linux-2.6.15/include/asm-powerpc/kexec.h
--- linux-2.6.15.suse/include/asm-powerpc/kexec.h 2006-02-08 04:10:24.000000000 +0100
+++ linux-2.6.15/include/asm-powerpc/kexec.h 2006-02-08 04:31:15.000000000 +0100
@@ -93,7 +93,8 @@ static inline void crash_setup_regs(stru
"mfxer %0\n"
"std %0, 296(%2)\n"
: "=&r" (tmp1), "=&r" (tmp2)
- : "b" (newregs));
+ : "b" (newregs)
+ : "memory");
}
}
#else
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] fix kexec asm
2006-03-08 2:35 [PATCH] fix kexec asm Chris Mason
@ 2006-03-08 4:16 ` Eric W. Biederman
2006-03-09 9:35 ` Pavel Machek
0 siblings, 1 reply; 3+ messages in thread
From: Eric W. Biederman @ 2006-03-08 4:16 UTC (permalink / raw
To: Chris Mason; +Cc: linux-kernel, akpm, mmlnx
Chris Mason <mason@suse.com> writes:
> From: Michael Matz <matz@suse.de>
>
> While testing kexec and kdump we hit problems where the new kernel would
> freeze or instantly reboot. The easiest way to trigger it was to kexec a
> kernel compiled for CONFIG_M586 on an athlon cpu. Compiling
> for CONFIG_MK7 instead would work fine.
>
> The patch below fixes a few problems with the kexec inline asm.
Thanks. Specifying the stomp of %eax in load_segments is definitely
good. The memory stomp looks excessive and if this was a fast path
I would worry about it. As it is better safe than sorry.
Acked-By: Eric Biederman <ebiederm@xmission.com>
Eric
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] fix kexec asm
2006-03-08 4:16 ` Eric W. Biederman
@ 2006-03-09 9:35 ` Pavel Machek
0 siblings, 0 replies; 3+ messages in thread
From: Pavel Machek @ 2006-03-09 9:35 UTC (permalink / raw
To: Eric W. Biederman; +Cc: Chris Mason, linux-kernel, akpm, mmlnx
On Út 07-03-06 21:16:34, Eric W. Biederman wrote:
> Chris Mason <mason@suse.com> writes:
>
> > From: Michael Matz <matz@suse.de>
> >
> > While testing kexec and kdump we hit problems where the new kernel would
> > freeze or instantly reboot. The easiest way to trigger it was to kexec a
> > kernel compiled for CONFIG_M586 on an athlon cpu. Compiling
> > for CONFIG_MK7 instead would work fine.
> >
> > The patch below fixes a few problems with the kexec inline asm.
>
> Thanks. Specifying the stomp of %eax in load_segments is definitely
> good. The memory stomp looks excessive and if this was a fast path
> I would worry about it. As it is better safe than sorry.
Why excessive? It reloads %ss, AFAICS; at that point, all the stack
potentially changes from gcc's POV.
Pavel
--
Web maintainer for suspend.sf.net (www.sf.net/projects/suspend) wanted...
^ permalink raw reply [flat|nested] 3+ messages in thread
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2006-03-08 4:16 ` Eric W. Biederman
2006-03-09 9:35 ` Pavel Machek
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