diff options
Diffstat (limited to 'meta-steppeeagle/recipes-kernel/linux/linux-yocto/0052-yocto-amd-clear-exceptions-in-AMD-FXSAVE-workaround.patch')
| -rw-r--r-- | meta-steppeeagle/recipes-kernel/linux/linux-yocto/0052-yocto-amd-clear-exceptions-in-AMD-FXSAVE-workaround.patch | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/meta-steppeeagle/recipes-kernel/linux/linux-yocto/0052-yocto-amd-clear-exceptions-in-AMD-FXSAVE-workaround.patch b/meta-steppeeagle/recipes-kernel/linux/linux-yocto/0052-yocto-amd-clear-exceptions-in-AMD-FXSAVE-workaround.patch new file mode 100644 index 00000000..ccc0d73a --- /dev/null +++ b/meta-steppeeagle/recipes-kernel/linux/linux-yocto/0052-yocto-amd-clear-exceptions-in-AMD-FXSAVE-workaround.patch @@ -0,0 +1,34 @@ +Backport of commit id 26bef1318adc1b3a530ecc807ef99346db2aa8b0 to kernel 3.12 + +Before we do an EMMS in the AMD FXSAVE information leak workaround we +need to clear any pending exceptions, otherwise we trap with a +floating-point exception inside this code. + +Reported-by: halfdog <me@halfdog.net> +Tested-by: Borislav Petkov <bp@suse.de> +Link: http://lkml.kernel.org/r/CA%2B55aFxQnY_PCG_n4=0w-VG=YLXL-yr7oMxyy0WU2gCBAf3ydg@mail.gmail.com +Signed-off-by: H. Peter Anvin <hpa@zytor.com> +Signed-off-by: Arindam Nath <arindam.nath@amd.com> +diff -Naur a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h +--- a/arch/x86/include/asm/fpu-internal.h 2013-11-04 05:11:51.000000000 +0530 ++++ b/arch/x86/include/asm/fpu-internal.h 2014-04-09 16:51:26.665126690 +0530 +@@ -293,12 +293,13 @@ + /* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception + is pending. Clear the x87 state here by setting it to fixed + values. "m" is a random variable that should be in L1 */ +- alternative_input( +- ASM_NOP8 ASM_NOP2, +- "emms\n\t" /* clear stack tags */ +- "fildl %P[addr]", /* set F?P to defined value */ +- X86_FEATURE_FXSAVE_LEAK, +- [addr] "m" (tsk->thread.fpu.has_fpu)); ++ if (unlikely(static_cpu_has(X86_FEATURE_FXSAVE_LEAK))) { ++ asm volatile( ++ "fnclex\n\t" ++ "emms\n\t" ++ "fildl %P[addr]" /* set F?P to defined value */ ++ : : [addr] "m" (tsk->thread.fpu.has_fpu)); ++ } + + return fpu_restore_checking(&tsk->thread.fpu); + } |