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authorAndy Lutomirski <[email protected]>2016-01-24 14:38:09 -0800
committerIngo Molnar <[email protected]>2016-02-09 15:42:56 +0100
commitc6ab109f7e0eae3bae3bb10f8ddb0df67735c150 (patch)
tree3afec625df2ba21a6bd7913ada3c6599d13f463d
parenta20d7297045f7fdcd676c15243192eb0e95a4306 (diff)
x86/fpu: Speed up lazy FPU restores slightly
If we have an FPU, there's no need to check CR0 for FPU emulation. Signed-off-by: Andy Lutomirski <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Fenghua Yu <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Quentin Casasnovas <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Sai Praneeth Prakhya <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: yu-cheng yu <[email protected]> Link: http://lkml.kernel.org/r/980004297e233c27066d54e71382c44cdd36ef7c.1453675014.git.luto@kernel.org Signed-off-by: Ingo Molnar <[email protected]>
-rw-r--r--arch/x86/kernel/traps.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 87f80febf477..36a9c017540e 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -752,7 +752,7 @@ do_device_not_available(struct pt_regs *regs, long error_code)
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
#ifdef CONFIG_MATH_EMULATION
- if (read_cr0() & X86_CR0_EM) {
+ if (!boot_cpu_has(X86_FEATURE_FPU) && (read_cr0() & X86_CR0_EM)) {
struct math_emu_info info = { };
conditional_sti(regs);