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

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 <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1309479572.2665.1372.camel@sbsiddha-MOBL3.sc.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Suresh Siddha 2011-06-30 17:19:32 -07:00 committed by H. Peter Anvin
parent b0af8dfdd6
commit 3e7cf5b00d
1 changed files with 4 additions and 0 deletions
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4
arch/x86/kernel/cpu/bugs.c
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@ -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");