x86/mmx: Use KFPU_387 for MMX string operations

Browse source

commit 67de8dca50 upstream.

The default kernel_fpu_begin() doesn't work on systems that support XMM but
haven't yet enabled CR4.OSFXSR.  This causes crashes when _mmx_memcpy() is
called too early because LDMXCSR generates #UD when the aforementioned bit
is clear.

Fix it by using kernel_fpu_begin_mask(KFPU_387) explicitly.

Fixes: 7ad816762f ("x86/fpu: Reset MXCSR to default in kernel_fpu_begin()")
Reported-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Krzysztof Piotr Olędzki <ole@ans.pl>
Tested-by: Krzysztof Mazur <krzysiek@podlesie.net>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/e7bf21855fe99e5f3baa27446e32623358f69e8d.1611205691.git.luto@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Andy Lutomirski 2021-01-20 21:09:49 -08:00 • committed by Greg Kroah-Hartman

parent f19c54317e

commit bd08075c86

1 changed files with 15 additions and 5 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

20

arch/x86/lib/mmx_32.c

View file