| Subject | Re: [PATCH 5.4 55/86] x86/mmx: Use KFPU_387 for MMX string operations | From | Krzysztof Olędzki <> | Date | Mon, 25 Jan 2021 23:03:18 -0800 |
| |
On 2021-01-25 at 10:39, Greg Kroah-Hartman wrote: > From: Andy Lutomirski <luto@kernel.org> > > commit 67de8dca50c027ca0fa3b62a488ee5035036a0da 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: 7ad816762f9b ("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>
Similar to 5.10.11, we also need https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e45122893a9870813f9bd7b4add4f613e6f29008 in 5.4.93:
Otherwise, the kernel will fail to compile if CONFIG_X86_USE_3DNOW=y
arch/x86/lib/mmx_32.c: In function '_mmx_memcpy': arch/x86/lib/mmx_32.c:50:2: error: implicit declaration of function 'kernel_fpu_begin_mask'; did you mean 'kernel_fpu_begin'? [-Werror=implicit-function-declaration] 50 | kernel_fpu_begin_mask(KFPU_387); | ^~~~~~~~~~~~~~~~~~~~~ | kernel_fpu_begin arch/x86/lib/mmx_32.c:50:24: error: 'KFPU_387' undeclared (first use in this function) 50 | kernel_fpu_begin_mask(KFPU_387); | ^~~~~~~~ arch/x86/lib/mmx_32.c:50:24: note: each undeclared identifier is reported only once for each function it appears in arch/x86/lib/mmx_32.c: In function 'fast_clear_page': arch/x86/lib/mmx_32.c:140:24: error: 'KFPU_387' undeclared (first use in this function) 140 | kernel_fpu_begin_mask(KFPU_387); | ^~~~~~~~ arch/x86/lib/mmx_32.c: In function 'fast_copy_page': arch/x86/lib/mmx_32.c:173:24: error: 'KFPU_387' undeclared (first use in this function) 173 | kernel_fpu_begin_mask(KFPU_387); | ^~~~~~~~
Thanks, Krzysztof
|