From: Borislav Petkov <bp@alien8.de>
To: Petteri Aimonen <jpa@git.mail.kapsi.fi>
Cc: Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, x86-ml <x86@kernel.org>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] arch/x86: reset MXCSR to default in kernel_fpu_begin()
Date: Tue, 2 Jun 2020 12:56:49 +0200 [thread overview]
Message-ID: <20200602105649.GB11634@zn.tnic> (raw)
In-Reply-To: <20200602102951.GE17423@lakka.kapsi.fi>
Hi,
On Tue, Jun 02, 2020 at 01:29:51PM +0300, Petteri Aimonen wrote:
> The kernel module is not actually x86-specific, even though it is
> currently only enabled for x86. amdgpu driver already does kernel mode
> floating point operations on PPC64 also, and the same module could be
> used to test the same thing there.
Then make it generic please and put the user portion in, say,
tools/testing/selftests/fpu/ and we can ask ppc people to test it too.
People might wanna add more stuff to it in the future, which would be
good.
> To deterministically trigger the bug, the syscall has to come from the
> same thread that has modified MXCSR. Going through /usr/sbin/modprobe
> won't work, and manually doing the necessary syscalls for module loading
> seems too complicated.
Ok, fair enough. But put that file in debugfs pls.
> The fesetround() and feenableexcept() are the portable ways to modify
> MXCSR. The test module does cause Precision Exception and Denormal
> Exception if those exceptions are unmasked.
Ok.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-06-02 10:56 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-02 10:11 [PATCH] arch/x86: reset MXCSR to default in kernel_fpu_begin() Borislav Petkov
2020-06-02 10:29 ` Petteri Aimonen
2020-06-02 10:56 ` Borislav Petkov [this message]
2020-06-02 17:03 ` Andy Lutomirski
2020-06-02 17:27 ` Shuah Khan
2020-06-02 19:50 ` Andy Lutomirski
2020-06-02 20:25 ` Shuah Khan
2020-06-03 5:19 ` Petteri Aimonen
2020-06-11 14:38 ` Shuah Khan
2020-06-11 7:36 ` Petteri Aimonen
2020-06-11 9:18 ` Borislav Petkov
2020-06-11 14:19 ` Andy Lutomirski
2020-06-11 14:50 ` Shuah Khan
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=20200602105649.GB11634@zn.tnic \
--to=bp@alien8.de \
--cc=dave.hansen@intel.com \
--cc=hpa@zytor.com \
--cc=jpa@git.mail.kapsi.fi \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--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