diff options
authorBorislav Petkov <bp@alien8.de>2016-03-11 12:32:06 +0100
committerIngo Molnar <mingo@kernel.org>2016-03-12 16:13:55 +0100
commit6e6867093de35141f0a76b66ac13f9f2e2c8e77a (patch)
parent84477336ec03f8061ffd6908da341e063e5d6d1f (diff)
x86/fpu: Fix eager-FPU handling on legacy FPU machines
i486 derived cores like Intel Quark support only the very old, legacy x87 FPU (FSAVE/FRSTOR, CPUID bit FXSR is not set), and our FPU code wasn't handling the saving and restoring there properly in the 'eagerfpu' case. So after we made eagerfpu the default for all CPU types: 58122bf1d856 x86/fpu: Default eagerfpu=on on all CPUs these old FPU designs broke. First, Andy Shevchenko reported a splat: WARNING: CPU: 0 PID: 823 at arch/x86/include/asm/fpu/internal.h:163 fpu__clear+0x8c/0x160 which was us trying to execute FXRSTOR on those machines even though they don't support it. After taking care of that, Bryan O'Donoghue reported that a simple FPU test still failed because we weren't initializing the FPU state properly on those machines. Take care of all that. Reported-and-tested-by: Bryan O'Donoghue <pure.logic@nexus-software.ie> Reported-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yu-cheng <yu-cheng.yu@intel.com> Link: http://lkml.kernel.org/r/20160311113206.GD4312@pd.tnic Signed-off-by: Ingo Molnar <mingo@kernel.org>
2 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index d25097c3fc1d..d5804adfa6da 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -409,8 +409,10 @@ static inline void copy_init_fpstate_to_fpregs(void)
if (use_xsave())
copy_kernel_to_xregs(&init_fpstate.xsave, -1);
- else
+ else if (static_cpu_has(X86_FEATURE_FXSR))
+ else
+ copy_kernel_to_fregs(&init_fpstate.fsave);
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 9ee7e307b18f..bd08fb77073d 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -134,7 +134,7 @@ static void __init fpu__init_system_generic(void)
* Set up the legacy init FPU context. (xstate init might overwrite this
* with a more modern format, if the CPU supports it.)
- fpstate_init_fxstate(&init_fpstate.fxsave);
+ fpstate_init(&init_fpstate);