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Commit 0bf23f3d authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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



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: default avatarBorislav 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: default avatarIngo Molnar <mingo@kernel.org>
parent e83ab9ad

arch/x86/kernel/fpu/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/fpu/bugs.c

0 → 100644
+64 −0
Original line number Diff line number Diff line 
/*

 * 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();

}

arch/x86/kernel/fpu/init.c

+0 −60
Original line number Diff line number Diff line
@@ -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:

 */