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Commit 82024135 authored by Brian Gerst's avatar Brian Gerst Committed by H. Peter Anvin
Browse files

x86-64, fpu: Simplify constraints for fxsave/fxtstor 



Use the "R" constraint (legacy register) instead of listing all the
possible registers.  Clean up the comments as well.

Signed-off-by: default avatarBrian Gerst <brgerst@gmail.com>
Acked-by: default avatarPekka Enberg <penberg@kernel.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1283563039-3466-8-git-send-email-brgerst@gmail.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 10c11f30

arch/x86/include/asm/i387.h

+17 −27
Original line number Diff line number Diff line
@@ -81,6 +81,7 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx) 
{

	int err;



	/* See comment in fxsave() below. */

	asm volatile("1:  rex64/fxrstor (%[fx])\n\t"

		     "2:\n"

		     ".section .fixup,\"ax\"\n"
@@ -89,11 +90,7 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx) 
		     ".previous\n"

		     _ASM_EXTABLE(1b, 3b)

		     : [err] "=r" (err)

#if 0 /* See comment in fxsave() below. */

		     : [fx] "r" (fx), "m" (*fx), "0" (0));

#else

		     : [fx] "cdaSDb" (fx), "m" (*fx), "0" (0));

#endif

		     : [fx] "R" (fx), "m" (*fx), "0" (0));

	return err;

}
@@ -140,6 +137,7 @@ static inline int fxsave_user(struct i387_fxsave_struct __user *fx) 
	if (unlikely(err))

		return -EFAULT;



	/* See comment in fxsave() below. */

	asm volatile("1:  rex64/fxsave (%[fx])\n\t"

		     "2:\n"

		     ".section .fixup,\"ax\"\n"
@@ -148,11 +146,7 @@ static inline int fxsave_user(struct i387_fxsave_struct __user *fx) 
		     ".previous\n"

		     _ASM_EXTABLE(1b, 3b)

		     : [err] "=r" (err), "=m" (*fx)

#if 0 /* See comment in fxsave() below. */

		     : [fx] "r" (fx), "0" (0));

#else

		     : [fx] "cdaSDb" (fx), "0" (0));

#endif

		     : [fx] "R" (fx), "0" (0));

	if (unlikely(err) &&

	    __clear_user(fx, sizeof(struct i387_fxsave_struct)))

		err = -EFAULT;
@@ -165,26 +159,22 @@ static inline void fpu_fxsave(struct fpu *fpu) 
	/* Using "rex64; fxsave %0" is broken because, if the memory operand

	   uses any extended registers for addressing, a second REX prefix

	   will be generated (to the assembler, rex64 followed by semicolon

	   is a separate instruction), and hence the 64-bitness is lost. */

#if 0

	/* Using "fxsaveq %0" would be the ideal choice, but is only supported

	   starting with gas 2.16. */

	__asm__ __volatile__("fxsaveq %0"

	   is a separate instruction), and hence the 64-bitness is lost.

	   Using "fxsaveq %0" would be the ideal choice, but is only supported

	   starting with gas 2.16.

	asm volatile("fxsaveq %0"

		     : "=m" (fpu->state->fxsave));

#elif 0

	/* Using, as a workaround, the properly prefixed form below isn't

	   Using, as a workaround, the properly prefixed form below isn't

	   accepted by any binutils version so far released, complaining that

	   the same type of prefix is used twice if an extended register is

	   needed for addressing (fix submitted to mainline 2005-11-21). */

	__asm__ __volatile__("rex64/fxsave %0"

	   needed for addressing (fix submitted to mainline 2005-11-21).

	asm volatile("rex64/fxsave %0"

		     : "=m" (fpu->state->fxsave));

#else

	/* This, however, we can work around by forcing the compiler to select

	   This, however, we can work around by forcing the compiler to select

	   an addressing mode that doesn't require extended registers. */

	__asm__ __volatile__("rex64/fxsave (%1)"

	asm volatile("rex64/fxsave (%[fx])"

		     : "=m" (fpu->state->fxsave)

			     : "cdaSDb" (&fpu->state->fxsave));

#endif

		     : [fx] "R" (&fpu->state->fxsave));

}



static inline void fpu_save_init(struct fpu *fpu)