x86-32, fpu: Fix DNA exception during check_fpu()

3e7cf5b0 · Suresh Siddha <[email protected]> · 2011-06-30 17:19:32 -07:00

Before check_fpu() is called, we have cr0.TS bit set and hence the floating
point code to check the FDIV bug was generating a DNA exception.

Use kernel_fpu_begin()/kernel_fpu_end() around the floating point
code to avoid this unnecessary device not available exception during
boot.

Signed-off-by: Suresh Siddha <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: H. Peter Anvin <[email protected]>

Commit: 3e7cf5b00dd5b577b4ee9b2a66e40fb670ef210b
Parents: b0af8dfd

Changes

1 files changed · +4 −0

File	Status	Add	Del	Content
arch/x86/kernel/cpu/bugs.c	modified	+4	−0	View file

arch/x86/kernel/cpu/bugs.c

View file

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 525514c..46674fb 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -62,6 +62,8 @@ static void __init check_fpu(void)
 		return;
 	}
 
+	kernel_fpu_begin();
+
 	/*
 	 * trap_init() enabled FXSR and company _before_ testing for FP
 	 * problems here.
@@ -80,6 +82,8 @@ static void __init check_fpu(void)
 		: "=m" (*&fdiv_bug)
 		: "m" (*&x), "m" (*&y));
 
+	kernel_fpu_end();
+
 	boot_cpu_data.fdiv_bug = fdiv_bug;
 	if (boot_cpu_data.fdiv_bug)
 		printk(KERN_WARNING "Hmm, FPU with FDIV bug.\n");