From: Avi Kivity <avi@redhat.com>
To: Tomas Racek <tracek@redhat.com>,
the arch/x86 maintainers <x86@kernel.org>
Cc: Michael Tokarev <mjt@tls.msk.ru>,
Borislav Petkov <borislav.petkov@amd.com>,
kvm-devel <kvm@vger.kernel.org>,
Marcelo Tosatti <mtosatti@redhat.com>,
qemu-devel@nongnu.org, linux-kernel@vger.kernel.org,
Anthony Liguori <anthony@codemonkey.ws>,
"H. Peter Anvin" <hpa@linux.intel.com>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Alan Cox <alan@linux.intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: [PATCH] x86, alternative: fix p6 nops on non-modular kernels
Date: Wed, 22 Aug 2012 13:03:48 +0300 [thread overview]
Message-ID: <5034AE84.90708@redhat.com> (raw)
In-Reply-To: <5034AC61.9030704@redhat.com>
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 <avi@redhat.com>
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 <tracek@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
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
next prev parent reply other threads:[~2012-08-22 10:04 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1104118228.1760802.1345121009530.JavaMail.root@redhat.com>
2012-08-16 13:35 ` x86, nops settings result in kernel crash Tomas Racek
2012-08-16 13:48 ` Borislav Petkov
2012-08-16 18:45 ` Tomas Racek
2012-08-16 18:53 ` Alan Cox
2012-08-16 21:30 ` H. Peter Anvin
2012-08-17 7:42 ` Tomas Racek
2012-08-16 21:51 ` [Qemu-devel] " Anthony Liguori
2012-08-17 7:43 ` Tomas Racek
2012-08-17 8:09 ` Borislav Petkov
2012-08-20 17:13 ` Tomas Racek
2012-08-21 7:22 ` Michael Tokarev
2012-08-21 9:28 ` Tomas Racek
2012-08-22 9:54 ` Avi Kivity
2012-08-22 10:03 ` Avi Kivity [this message]
2012-08-22 10:21 ` [tip:x86/urgent] x86/alternatives: Fix p6 nops on non-modular kernels tip-bot for Avi Kivity
2012-08-22 10:33 ` [PATCH] x86, alternative: fix " Tomas Racek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5034AE84.90708@redhat.com \
--to=avi@redhat.com \
--cc=alan@linux.intel.com \
--cc=alan@lxorguk.ukuu.org.uk \
--cc=anthony@codemonkey.ws \
--cc=borislav.petkov@amd.com \
--cc=hpa@linux.intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mjt@tls.msk.ru \
--cc=mtosatti@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=tracek@redhat.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).