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x86/fpu: Factor out FPU bug checks into fpu/bugs.c

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Create separate fpu/bugs.c code so that if we read generic FPU code
we don't have to wade through all the bugcheck related code first.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2015-04-26 14:48:08 +02:00
parent e83ab9ad97
commit 0bf23f3d6c
3 changed files with 65 additions and 61 deletions
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2
arch/x86/kernel/fpu/Makefile
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@ -2,4 +2,4 @@
# Build rules for the FPU support code:
#
obj-y += init.o core.o xsave.o
obj-y += init.o bugs.o core.o xsave.o

64
arch/x86/kernel/fpu/bugs.c Normal file
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@ -0,0 +1,64 @@
/*
* x86 FPU bug checks:
*/
#include <asm/fpu/internal.h>
/*
* Boot time CPU/FPU FDIV bug detection code:
*/
static double __initdata x = 4195835.0;
static double __initdata y = 3145727.0;
/*
* This used to check for exceptions..
* However, it turns out that to support that,
* the XMM trap handlers basically had to
* be buggy. So let's have a correct XMM trap
* handler, and forget about printing out
* some status at boot.
*
* We should really only care about bugs here
* anyway. Not features.
*/
static void __init check_fpu(void)
{
s32 fdiv_bug;
kernel_fpu_begin();
/*
* trap_init() enabled FXSR and company _before_ testing for FP
* problems here.
*
* Test for the divl bug: http://en.wikipedia.org/wiki/Fdiv_bug
*/
__asm__("fninit\n\t"
"fldl %1\n\t"
"fdivl %2\n\t"
"fmull %2\n\t"
"fldl %1\n\t"
"fsubp %%st,%%st(1)\n\t"
"fistpl %0\n\t"
"fwait\n\t"
"fninit"
: "=m" (*&fdiv_bug)
: "m" (*&x), "m" (*&y));
kernel_fpu_end();
if (fdiv_bug) {
set_cpu_bug(&boot_cpu_data, X86_BUG_FDIV);
pr_warn("Hmm, FPU with FDIV bug\n");
}
}
void fpu__init_check_bugs(void)
{
/*
* kernel_fpu_begin/end() in check_fpu() relies on the patched
* alternative instructions.
*/
if (cpu_has_fpu)
check_fpu();
}

60
arch/x86/kernel/fpu/init.c
View File

@ -4,66 +4,6 @@
#include <asm/fpu/internal.h>
#include <asm/tlbflush.h>
/*
* Boot time CPU/FPU FDIV bug detection code:
*/
static double __initdata x = 4195835.0;
static double __initdata y = 3145727.0;
/*
* This used to check for exceptions..
* However, it turns out that to support that,
* the XMM trap handlers basically had to
* be buggy. So let's have a correct XMM trap
* handler, and forget about printing out
* some status at boot.
*
* We should really only care about bugs here
* anyway. Not features.
*/
static void __init check_fpu(void)
{
s32 fdiv_bug;
kernel_fpu_begin();
/*
* trap_init() enabled FXSR and company _before_ testing for FP
* problems here.
*
* Test for the divl bug: http://en.wikipedia.org/wiki/Fdiv_bug
*/
__asm__("fninit\n\t"
"fldl %1\n\t"
"fdivl %2\n\t"
"fmull %2\n\t"
"fldl %1\n\t"
"fsubp %%st,%%st(1)\n\t"
"fistpl %0\n\t"
"fwait\n\t"
"fninit"
: "=m" (*&fdiv_bug)
: "m" (*&x), "m" (*&y));
kernel_fpu_end();
if (fdiv_bug) {
set_cpu_bug(&boot_cpu_data, X86_BUG_FDIV);
pr_warn("Hmm, FPU with FDIV bug\n");
}
}
void fpu__init_check_bugs(void)
{
/*
* kernel_fpu_begin/end() in check_fpu() relies on the patched
* alternative instructions.
*/
if (cpu_has_fpu)
check_fpu();
}
/*
* The earliest FPU detection code:
*/