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Re: [Qemu-devel] [PATCH] x86, alternative: fix p6 nops on non-modular ke
From: |
Tomas Racek |
Subject: |
Re: [Qemu-devel] [PATCH] x86, alternative: fix p6 nops on non-modular kernels |
Date: |
Wed, 22 Aug 2012 06:33:40 -0400 (EDT) |
----- Original Message -----
> 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.
>
Works fine. Thank you!
Tom
> -------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, 2012/08/22
- Re: [Qemu-devel] [PATCH] x86, alternative: fix p6 nops on non-modular kernels,
Tomas Racek <=