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[Qemu-devel] [PATCH] x86, alternative: fix p6 nops on non-modular kernel
From: |
Avi Kivity |
Subject: |
[Qemu-devel] [PATCH] x86, alternative: fix p6 nops on non-modular kernels |
Date: |
Wed, 22 Aug 2012 13:03:48 +0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 |
On 08/22/2012 12:54 PM, Avi Kivity wrote:
> On 08/21/2012 12:28 PM, Tomas Racek wrote:
>>
>> http://fi.muni.cz/~xracek/debian2.img.bz2
>>
>> Other things are the same.
>>
>> The runtest.sh sets environment for xfstests and runs test 285 which I wrote
>> and and which should test if FS sends discard requests only on free sectors:
>> 285:
>> 1. Create loop device and FS on it.
>> 2. Populate it with some garbage.
>> 3. Get free sectors from FS.
>> 4. Run fstrim and look for discard requests via blk tracer.
>> 5. Compare free sectors to discard requests.
>>
>> The test itself can have some issues but I'm pretty sure it shouldn't crash
>> the system. ;-)
>
> Does the following patch help?
>
It's obvious that it should. You're running a non-modular kernel, and those
nops are discarded (probably a leftover from the days patching was a boot-only
activity), so the kernel patched garbage over its own code.
-------8<----cut-here-----8<-----------------------------------
From: Avi Kivity <address@hidden>
Date: Wed, 22 Aug 2012 12:58:18 +0300
Subject: [PATCH] x86, alternative: fix p6 nops on non-modular kernels
Probably a leftover from the early days of self-patching, p6nops are
marked __initconst_or_module, which causes them to be discarded in a
non-modular kernel. If something later triggers patching, it will
overwrite kernel code with garbage.
Reported-by: Tomas Racek <address@hidden>
Signed-off-by: Avi Kivity <address@hidden>
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index afb7ff7..ced4534 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -165,7 +165,7 @@ static int __init setup_noreplace_paravirt(char *str)
#endif
#ifdef P6_NOP1
-static const unsigned char __initconst_or_module p6nops[] =
+static const unsigned char p6nops[] =
{
P6_NOP1,
P6_NOP2,
--
error compiling committee.c: too many arguments to function
- Re: [Qemu-devel] x86, nops settings result in kernel crash, (continued)
- Re: [Qemu-devel] x86, nops settings result in kernel crash, Anthony Liguori, 2012/08/16
- Re: [Qemu-devel] x86, nops settings result in kernel crash, Tomas Racek, 2012/08/17
- Re: [Qemu-devel] x86, nops settings result in kernel crash, Borislav Petkov, 2012/08/17
- Re: [Qemu-devel] x86, nops settings result in kernel crash, Tomas Racek, 2012/08/20
- Re: [Qemu-devel] x86, nops settings result in kernel crash, Michael Tokarev, 2012/08/21
- Re: [Qemu-devel] x86, nops settings result in kernel crash, Tomas Racek, 2012/08/21
- Re: [Qemu-devel] x86, nops settings result in kernel crash, Avi Kivity, 2012/08/22
- [Qemu-devel] [PATCH] x86, alternative: fix p6 nops on non-modular kernels,
Avi Kivity <=
- Re: [Qemu-devel] [PATCH] x86, alternative: fix p6 nops on non-modular kernels, Tomas Racek, 2012/08/22