From 820241356d6aa9a895fc10def15794a5a5bfcd98 Mon Sep 17 00:00:00 2001 From: Brian Gerst Date: Fri, 3 Sep 2010 21:17:14 -0400 Subject: [PATCH] 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: Brian Gerst Acked-by: Pekka Enberg Cc: Suresh Siddha LKML-Reference: <1283563039-3466-8-git-send-email-brgerst@gmail.com> Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/i387.h | 44 ++++++++++++++----------------------- 1 file changed, 17 insertions(+), 27 deletions(-) diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index 8b40a8379cc2..768fcb25900a 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -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" - : "=m" (fpu->state->fxsave)); -#elif 0 - /* Using, as a workaround, the properly prefixed form below isn't + 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)); + 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" - : "=m" (fpu->state->fxsave)); -#else - /* This, however, we can work around by forcing the compiler to select + needed for addressing (fix submitted to mainline 2005-11-21). + asm volatile("rex64/fxsave %0" + : "=m" (fpu->state->fxsave)); + 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)" - : "=m" (fpu->state->fxsave) - : "cdaSDb" (&fpu->state->fxsave)); -#endif + asm volatile("rex64/fxsave (%[fx])" + : "=m" (fpu->state->fxsave) + : [fx] "R" (&fpu->state->fxsave)); } static inline void fpu_save_init(struct fpu *fpu) -- 2.39.5