diff options
| -rw-r--r-- | include/asm-x86_64/i387.h | 58 |
1 files changed, 48 insertions, 10 deletions
diff --git a/include/asm-x86_64/i387.h b/include/asm-x86_64/i387.h index aa39cfd0e00..57f7e143384 100644 --- a/include/asm-x86_64/i387.h +++ b/include/asm-x86_64/i387.h @@ -75,7 +75,8 @@ extern int set_fpregs(struct task_struct *tsk, static inline int restore_fpu_checking(struct i387_fxsave_struct *fx) { int err; - asm volatile("1: rex64 ; fxrstor (%[fx])\n\t" + + asm volatile("1: rex64/fxrstor (%[fx])\n\t" "2:\n" ".section .fixup,\"ax\"\n" "3: movl $-1,%[err]\n" @@ -86,7 +87,11 @@ static inline int restore_fpu_checking(struct i387_fxsave_struct *fx) " .quad 1b,3b\n" ".previous" : [err] "=r" (err) - : [fx] "r" (fx), "0" (0)); +#if 0 /* See comment in __fxsave_clear() below. */ + : [fx] "r" (fx), "m" (*fx), "0" (0)); +#else + : [fx] "cdaSDb" (fx), "m" (*fx), "0" (0)); +#endif if (unlikely(err)) init_fpu(current); return err; @@ -95,7 +100,8 @@ static inline int restore_fpu_checking(struct i387_fxsave_struct *fx) static inline int save_i387_checking(struct i387_fxsave_struct __user *fx) { int err; - asm volatile("1: rex64 ; fxsave (%[fx])\n\t" + + asm volatile("1: rex64/fxsave (%[fx])\n\t" "2:\n" ".section .fixup,\"ax\"\n" "3: movl $-1,%[err]\n" @@ -105,20 +111,53 @@ static inline int save_i387_checking(struct i387_fxsave_struct __user *fx) " .align 8\n" " .quad 1b,3b\n" ".previous" - : [err] "=r" (err) - : [fx] "r" (fx), "0" (0)); + : [err] "=r" (err), "=m" (*fx) +#if 0 /* See comment in __fxsave_clear() below. */ + : [fx] "r" (fx), "0" (0)); +#else + : [fx] "cdaSDb" (fx), "0" (0)); +#endif if (unlikely(err)) __clear_user(fx, sizeof(struct i387_fxsave_struct)); return err; } +static inline void __fxsave_clear(struct task_struct *tsk) +{ + /* 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" (tsk->thread.i387.fxsave)); +#elif 0 + /* 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" (tsk->thread.i387.fxsave)); +#else + /* 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 %P2(%1)" + : "=m" (tsk->thread.i387.fxsave) + : "cdaSDb" (tsk), + "i" (offsetof(__typeof__(*tsk), + thread.i387.fxsave))); +#endif + __asm__ __volatile__("fnclex"); +} + static inline void kernel_fpu_begin(void) { struct thread_info *me = current_thread_info(); preempt_disable(); - if (me->status & TS_USEDFPU) { - asm volatile("rex64 ; fxsave %0 ; fnclex" - : "=m" (me->task->thread.i387.fxsave)); + if (me->status & TS_USEDFPU) { + __fxsave_clear(me->task); me->status &= ~TS_USEDFPU; return; } @@ -133,8 +172,7 @@ static inline void kernel_fpu_end(void) static inline void save_init_fpu( struct task_struct *tsk ) { - asm volatile( "rex64 ; fxsave %0 ; fnclex" - : "=m" (tsk->thread.i387.fxsave)); + __fxsave_clear(tsk); tsk->thread_info->status &= ~TS_USEDFPU; stts(); } |