arch/x86/include/asm/fpu-internal.h - linux - Git at Google

 /*
  * Copyright (C) 1994 Linus Torvalds
  *
  * Pentium III FXSR, SSE support
  * General FPU state handling cleanups
  *	Gareth Hughes <gareth@valinux.com>, May 2000
  * x86-64 work by Andi Kleen 2002
  */

 #ifndef _FPU_INTERNAL_H
 #define _FPU_INTERNAL_H

 #include <linux/kernel_stat.h>
 #include <linux/regset.h>
 #include <linux/compat.h>
 #include <linux/slab.h>
 #include <asm/asm.h>
 #include <asm/cpufeature.h>
 #include <asm/processor.h>
 #include <asm/sigcontext.h>
 #include <asm/user.h>
 #include <asm/uaccess.h>
 #include <asm/xsave.h>
 #include <asm/smap.h>

 #ifdef CONFIG_X86_64
 # include <asm/sigcontext32.h>
 # include <asm/user32.h>
 struct ksignal;
 int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
 			compat_sigset_t *set, struct pt_regs *regs);
 int ia32_setup_frame(int sig, struct ksignal *ksig,
 		     compat_sigset_t *set, struct pt_regs *regs);
 #else
 # define user_i387_ia32_struct	user_i387_struct
 # define user32_fxsr_struct	user_fxsr_struct
 # define ia32_setup_frame	__setup_frame
 # define ia32_setup_rt_frame	__setup_rt_frame
 #endif

 extern unsigned int mxcsr_feature_mask;
 extern void fpu_init(void);
 extern void eager_fpu_init(void);

 DECLARE_PER_CPU(struct task_struct *, fpu_owner_task);

 extern void convert_from_fxsr(struct user_i387_ia32_struct *env,
 			      struct task_struct *tsk);
 extern void convert_to_fxsr(struct task_struct *tsk,
 			    const struct user_i387_ia32_struct *env);

 extern user_regset_active_fn fpregs_active, xfpregs_active;
 extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get,
 				xstateregs_get;
 extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set,
 				 xstateregs_set;

 /*
  * xstateregs_active == fpregs_active. Please refer to the comment
  * at the definition of fpregs_active.
  */
 #define xstateregs_active	fpregs_active

 #ifdef CONFIG_MATH_EMULATION
 extern void finit_soft_fpu(struct i387_soft_struct *soft);
 #else
 static inline void finit_soft_fpu(struct i387_soft_struct *soft) {}
 #endif

 static inline int is_ia32_compat_frame(void)
 {
 	return config_enabled(CONFIG_IA32_EMULATION) &&
 	       test_thread_flag(TIF_IA32);
 }

 static inline int is_ia32_frame(void)
 {
 	return config_enabled(CONFIG_X86_32) || is_ia32_compat_frame();
 }

 static inline int is_x32_frame(void)
 {
 	return config_enabled(CONFIG_X86_X32_ABI) && test_thread_flag(TIF_X32);
 }

 #define X87_FSW_ES (1 << 7)	/* Exception Summary */

 static __always_inline __pure bool use_eager_fpu(void)
 {
 	return static_cpu_has_safe(X86_FEATURE_EAGER_FPU);
 }

 static __always_inline __pure bool use_xsaveopt(void)
 {
 	return static_cpu_has_safe(X86_FEATURE_XSAVEOPT);
 }

 static __always_inline __pure bool use_xsave(void)
 {
 	return static_cpu_has_safe(X86_FEATURE_XSAVE);
 }

 static __always_inline __pure bool use_fxsr(void)
 {
 	return static_cpu_has_safe(X86_FEATURE_FXSR);
 }

 static inline void fx_finit(struct i387_fxsave_struct *fx)
 {
 	memset(fx, 0, xstate_size);
 	fx->cwd = 0x37f;
 	fx->mxcsr = MXCSR_DEFAULT;
 }

 extern void __sanitize_i387_state(struct task_struct *);

 static inline void sanitize_i387_state(struct task_struct *tsk)
 {
 	if (!use_xsaveopt())
 		return;
 	__sanitize_i387_state(tsk);
 }

 #define user_insn(insn, output, input...)				\
 ({									\
 	int err;							\
 	asm volatile(ASM_STAC "\n"					\
 		     "1:" #insn "\n\t"					\
 		     "2: " ASM_CLAC "\n"				\
 		     ".section .fixup,\"ax\"\n"				\
 		     "3:  movl $-1,%[err]\n"				\
 		     "    jmp  2b\n"					\
 		     ".previous\n"					\
 		     _ASM_EXTABLE(1b, 3b)				\
 		     : [err] "=r" (err), output				\
 		     : "0"(0), input);					\
 	err;								\
 })

 #define check_insn(insn, output, input...)				\
 ({									\
 	int err;							\
 	asm volatile("1:" #insn "\n\t"					\
 		     "2:\n"						\
 		     ".section .fixup,\"ax\"\n"				\
 		     "3:  movl $-1,%[err]\n"				\
 		     "    jmp  2b\n"					\
 		     ".previous\n"					\
 		     _ASM_EXTABLE(1b, 3b)				\
 		     : [err] "=r" (err), output				\
 		     : "0"(0), input);					\
 	err;								\
 })

 static inline int fsave_user(struct i387_fsave_struct __user *fx)
 {
 	return user_insn(fnsave %[fx]; fwait,  [fx] "=m" (*fx), "m" (*fx));
 }

 static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
 {
 	if (config_enabled(CONFIG_X86_32))
 		return user_insn(fxsave %[fx], [fx] "=m" (*fx), "m" (*fx));
 	else if (config_enabled(CONFIG_AS_FXSAVEQ))
 		return user_insn(fxsaveq %[fx], [fx] "=m" (*fx), "m" (*fx));

 	/* See comment in fpu_fxsave() below. */
 	return user_insn(rex64/fxsave (%[fx]), "=m" (*fx), [fx] "R" (fx));
 }

 static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
 {
 	if (config_enabled(CONFIG_X86_32))
 		return check_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
 	else if (config_enabled(CONFIG_AS_FXSAVEQ))
 		return check_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));

 	/* See comment in fpu_fxsave() below. */
 	return check_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),
 			  "m" (*fx));
 }

 static inline int fxrstor_user(struct i387_fxsave_struct __user *fx)
 {
 	if (config_enabled(CONFIG_X86_32))
 		return user_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
 	else if (config_enabled(CONFIG_AS_FXSAVEQ))
 		return user_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));

 	/* See comment in fpu_fxsave() below. */
 	return user_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),
 			  "m" (*fx));
 }

 static inline int frstor_checking(struct i387_fsave_struct *fx)
 {
 	return check_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
 }

 static inline int frstor_user(struct i387_fsave_struct __user *fx)
 {
 	return user_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
 }

 static inline void fpu_fxsave(struct fpu *fpu)
 {
 	if (config_enabled(CONFIG_X86_32))
 		asm volatile( "fxsave %[fx]" : [fx] "=m" (fpu->state->fxsave));
 	else if (config_enabled(CONFIG_AS_FXSAVEQ))
 		asm volatile("fxsaveq %0" : "=m" (fpu->state->fxsave));
 	else {
 		/* 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.
 		 *
 		 * Using "fxsaveq %0" would be the ideal choice, but is only
 		 * supported starting with gas 2.16.
 		 *
 		 * 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));
 		 *
 		 * 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 (%[fx])"
 			     : "=m" (fpu->state->fxsave)
 			     : [fx] "R" (&fpu->state->fxsave));
 	}
 }

 /*
  * These must be called with preempt disabled. Returns
  * 'true' if the FPU state is still intact.
  */
 static inline int fpu_save_init(struct fpu *fpu)
 {
 	if (use_xsave()) {
 		fpu_xsave(fpu);

 		/*
 		 * xsave header may indicate the init state of the FP.
 		 */
 		if (!(fpu->state->xsave.xsave_hdr.xstate_bv & XSTATE_FP))
 			return 1;
 	} else if (use_fxsr()) {
 		fpu_fxsave(fpu);
 	} else {
 		asm volatile("fnsave %[fx]; fwait"
 			     : [fx] "=m" (fpu->state->fsave));
 		return 0;
 	}

 	/*
 	 * If exceptions are pending, we need to clear them so
 	 * that we don't randomly get exceptions later.
 	 *
 	 * FIXME! Is this perhaps only true for the old-style
 	 * irq13 case? Maybe we could leave the x87 state
 	 * intact otherwise?
 	 */
 	if (unlikely(fpu->state->fxsave.swd & X87_FSW_ES)) {
 		asm volatile("fnclex");
 		return 0;
 	}
 	return 1;
 }

 static inline int __save_init_fpu(struct task_struct *tsk)
 {
 	return fpu_save_init(&tsk->thread.fpu);
 }

 static inline int fpu_restore_checking(struct fpu *fpu)
 {
 	if (use_xsave())
 		return fpu_xrstor_checking(&fpu->state->xsave);
 	else if (use_fxsr())
 		return fxrstor_checking(&fpu->state->fxsave);
 	else
 		return frstor_checking(&fpu->state->fsave);
 }

 static inline int restore_fpu_checking(struct task_struct *tsk)
 {
 	/* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception
 	   is pending.  Clear the x87 state here by setting it to fixed
 	   values. "m" is a random variable that should be in L1 */
 	if (unlikely(static_cpu_has_bug_safe(X86_BUG_FXSAVE_LEAK))) {
 		asm volatile(
 			"fnclex\n\t"
 			"emms\n\t"
 			"fildl %P[addr]"	/* set F?P to defined value */
 			: : [addr] "m" (tsk->thread.fpu.has_fpu));
 	}

 	return fpu_restore_checking(&tsk->thread.fpu);
 }

 /*
  * Software FPU state helpers. Careful: these need to
  * be preemption protection *and* they need to be
  * properly paired with the CR0.TS changes!
  */
 static inline int __thread_has_fpu(struct task_struct *tsk)
 {
 	return tsk->thread.fpu.has_fpu;
 }

 /* Must be paired with an 'stts' after! */
 static inline void __thread_clear_has_fpu(struct task_struct *tsk)
 {
 	tsk->thread.fpu.has_fpu = 0;
 	this_cpu_write(fpu_owner_task, NULL);
 }

 /* Must be paired with a 'clts' before! */
 static inline void __thread_set_has_fpu(struct task_struct *tsk)
 {
 	tsk->thread.fpu.has_fpu = 1;
 	this_cpu_write(fpu_owner_task, tsk);
 }

 /*
  * Encapsulate the CR0.TS handling together with the
  * software flag.
  *
  * These generally need preemption protection to work,
  * do try to avoid using these on their own.
  */
 static inline void __thread_fpu_end(struct task_struct *tsk)
 {
 	__thread_clear_has_fpu(tsk);
 	if (!use_eager_fpu())
 		stts();
 }

 static inline void __thread_fpu_begin(struct task_struct *tsk)
 {
 	if (!static_cpu_has_safe(X86_FEATURE_EAGER_FPU))
 		clts();
 	__thread_set_has_fpu(tsk);
 }

 static inline void __drop_fpu(struct task_struct *tsk)
 {
 	if (__thread_has_fpu(tsk)) {
 		/* Ignore delayed exceptions from user space */
 		asm volatile("1: fwait\n"
 			     "2:\n"
 			     _ASM_EXTABLE(1b, 2b));
 		__thread_fpu_end(tsk);
 	}
 }

 static inline void drop_fpu(struct task_struct *tsk)
 {
 	/*
 	 * Forget coprocessor state..
 	 */
 	preempt_disable();
 	tsk->thread.fpu_counter = 0;
 	__drop_fpu(tsk);
 	clear_used_math();
 	preempt_enable();
 }

 static inline void drop_init_fpu(struct task_struct *tsk)
 {
 	if (!use_eager_fpu())
 		drop_fpu(tsk);
 	else {
 		if (use_xsave())
 			xrstor_state(init_xstate_buf, -1);
 		else
 			fxrstor_checking(&init_xstate_buf->i387);
 	}
 }

 /*
  * FPU state switching for scheduling.
  *
  * This is a two-stage process:
  *
  *  - switch_fpu_prepare() saves the old state and
  *    sets the new state of the CR0.TS bit. This is
  *    done within the context of the old process.
  *
  *  - switch_fpu_finish() restores the new state as
  *    necessary.
  */
 typedef struct { int preload; } fpu_switch_t;

 /*
  * Must be run with preemption disabled: this clears the fpu_owner_task,
  * on this CPU.
  *
  * This will disable any lazy FPU state restore of the current FPU state,
  * but if the current thread owns the FPU, it will still be saved by.
  */
 static inline void __cpu_disable_lazy_restore(unsigned int cpu)
 {
 	per_cpu(fpu_owner_task, cpu) = NULL;
 }

 static inline int fpu_lazy_restore(struct task_struct *new, unsigned int cpu)
 {
 	return new == this_cpu_read_stable(fpu_owner_task) &&
 		cpu == new->thread.fpu.last_cpu;
 }

 static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct task_struct *new, int cpu)
 {
 	fpu_switch_t fpu;

 	/*
 	 * If the task has used the math, pre-load the FPU on xsave processors
 	 * or if the past 5 consecutive context-switches used math.
 	 */
 	fpu.preload = tsk_used_math(new) && (use_eager_fpu() ||
 					     new->thread.fpu_counter > 5);
 	if (__thread_has_fpu(old)) {
 		if (!__save_init_fpu(old))
 			cpu = ~0;
 		old->thread.fpu.last_cpu = cpu;
 		old->thread.fpu.has_fpu = 0;	/* But leave fpu_owner_task! */

 		/* Don't change CR0.TS if we just switch! */
 		if (fpu.preload) {
 			new->thread.fpu_counter++;
 			__thread_set_has_fpu(new);
 			prefetch(new->thread.fpu.state);
 		} else if (!use_eager_fpu())
 			stts();
 	} else {
 		old->thread.fpu_counter = 0;
 		old->thread.fpu.last_cpu = ~0;
 		if (fpu.preload) {
 			new->thread.fpu_counter++;
 			if (!use_eager_fpu() && fpu_lazy_restore(new, cpu))
 				fpu.preload = 0;
 			else
 				prefetch(new->thread.fpu.state);
 			__thread_fpu_begin(new);
 		}
 	}
 	return fpu;
 }

 /*
  * By the time this gets called, we've already cleared CR0.TS and
  * given the process the FPU if we are going to preload the FPU
  * state - all we need to do is to conditionally restore the register
  * state itself.
  */
 static inline void switch_fpu_finish(struct task_struct *new, fpu_switch_t fpu)
 {
 	if (fpu.preload) {
 		if (unlikely(restore_fpu_checking(new)))
 			drop_init_fpu(new);
 	}
 }

 /*
  * Signal frame handlers...
  */
 extern int save_xstate_sig(void __user *buf, void __user *fx, int size);
 extern int __restore_xstate_sig(void __user *buf, void __user *fx, int size);

 static inline int xstate_sigframe_size(void)
 {
 	return use_xsave() ? xstate_size + FP_XSTATE_MAGIC2_SIZE : xstate_size;
 }

 static inline int restore_xstate_sig(void __user *buf, int ia32_frame)
 {
 	void __user *buf_fx = buf;
 	int size = xstate_sigframe_size();

 	if (ia32_frame && use_fxsr()) {
 		buf_fx = buf + sizeof(struct i387_fsave_struct);
 		size += sizeof(struct i387_fsave_struct);
 	}

 	return __restore_xstate_sig(buf, buf_fx, size);
 }

 /*
  * Need to be preemption-safe.
  *
  * NOTE! user_fpu_begin() must be used only immediately before restoring
  * it. This function does not do any save/restore on their own.
  */
 static inline void user_fpu_begin(void)
 {
 	preempt_disable();
 	if (!user_has_fpu())
 		__thread_fpu_begin(current);
 	preempt_enable();
 }

 static inline void __save_fpu(struct task_struct *tsk)
 {
 	if (use_xsave()) {
 		if (unlikely(system_state == SYSTEM_BOOTING))
 			xsave_state_booting(&tsk->thread.fpu.state->xsave, -1);
 		else
 			xsave_state(&tsk->thread.fpu.state->xsave, -1);
 	} else
 		fpu_fxsave(&tsk->thread.fpu);
 }

 /*
  * These disable preemption on their own and are safe
  */
 static inline void save_init_fpu(struct task_struct *tsk)
 {
 	WARN_ON_ONCE(!__thread_has_fpu(tsk));

 	if (use_eager_fpu()) {
 		__save_fpu(tsk);
 		return;
 	}

 	preempt_disable();
 	__save_init_fpu(tsk);
 	__thread_fpu_end(tsk);
 	preempt_enable();
 }

 /*
  * i387 state interaction
  */
 static inline unsigned short get_fpu_cwd(struct task_struct *tsk)
 {
 	if (cpu_has_fxsr) {
 		return tsk->thread.fpu.state->fxsave.cwd;
 	} else {
 		return (unsigned short)tsk->thread.fpu.state->fsave.cwd;
 	}
 }

 static inline unsigned short get_fpu_swd(struct task_struct *tsk)
 {
 	if (cpu_has_fxsr) {
 		return tsk->thread.fpu.state->fxsave.swd;
 	} else {
 		return (unsigned short)tsk->thread.fpu.state->fsave.swd;
 	}
 }

 static inline unsigned short get_fpu_mxcsr(struct task_struct *tsk)
 {
 	if (cpu_has_xmm) {
 		return tsk->thread.fpu.state->fxsave.mxcsr;
 	} else {
 		return MXCSR_DEFAULT;
 	}
 }

 static bool fpu_allocated(struct fpu *fpu)
 {
 	return fpu->state != NULL;
 }

 static inline int fpu_alloc(struct fpu *fpu)
 {
 	if (fpu_allocated(fpu))
 		return 0;
 	fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL);
 	if (!fpu->state)
 		return -ENOMEM;
 	WARN_ON((unsigned long)fpu->state & 15);
 	return 0;
 }

 static inline void fpu_free(struct fpu *fpu)
 {
 	if (fpu->state) {
 		kmem_cache_free(task_xstate_cachep, fpu->state);
 		fpu->state = NULL;
 	}
 }

 static inline void fpu_copy(struct task_struct *dst, struct task_struct *src)
 {
 	if (use_eager_fpu()) {
 		memset(&dst->thread.fpu.state->xsave, 0, xstate_size);
 		__save_fpu(dst);
 	} else {
 		struct fpu *dfpu = &dst->thread.fpu;
 		struct fpu *sfpu = &src->thread.fpu;

 		unlazy_fpu(src);
 		memcpy(dfpu->state, sfpu->state, xstate_size);
 	}
 }

 static inline unsigned long
 alloc_mathframe(unsigned long sp, int ia32_frame, unsigned long *buf_fx,
 		unsigned long *size)
 {
 	unsigned long frame_size = xstate_sigframe_size();

 	*buf_fx = sp = round_down(sp - frame_size, 64);
 	if (ia32_frame && use_fxsr()) {
 		frame_size += sizeof(struct i387_fsave_struct);
 		sp -= sizeof(struct i387_fsave_struct);
 	}

 	*size = frame_size;
 	return sp;
 }

 #endif
	/*
	* Copyright (C) 1994 Linus Torvalds
	*
	* Pentium III FXSR, SSE support
	* General FPU state handling cleanups
	* Gareth Hughes <gareth@valinux.com>, May 2000
	* x86-64 work by Andi Kleen 2002
	*/

	#ifndef _FPU_INTERNAL_H
	#define _FPU_INTERNAL_H

	#include <linux/kernel_stat.h>
	#include <linux/regset.h>
	#include <linux/compat.h>
	#include <linux/slab.h>
	#include <asm/asm.h>
	#include <asm/cpufeature.h>
	#include <asm/processor.h>
	#include <asm/sigcontext.h>
	#include <asm/user.h>
	#include <asm/uaccess.h>
	#include <asm/xsave.h>
	#include <asm/smap.h>

	#ifdef CONFIG_X86_64
	# include <asm/sigcontext32.h>
	# include <asm/user32.h>
	struct ksignal;
	int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
	compat_sigset_t set, struct pt_regs regs);
	int ia32_setup_frame(int sig, struct ksignal *ksig,
	compat_sigset_t set, struct pt_regs regs);
	#else
	# define user_i387_ia32_struct user_i387_struct
	# define user32_fxsr_struct user_fxsr_struct
	# define ia32_setup_frame __setup_frame
	# define ia32_setup_rt_frame __setup_rt_frame
	#endif

	extern unsigned int mxcsr_feature_mask;
	extern void fpu_init(void);
	extern void eager_fpu_init(void);

	DECLARE_PER_CPU(struct task_struct *, fpu_owner_task);

	extern void convert_from_fxsr(struct user_i387_ia32_struct *env,
	struct task_struct *tsk);
	extern void convert_to_fxsr(struct task_struct *tsk,
	const struct user_i387_ia32_struct *env);

	extern user_regset_active_fn fpregs_active, xfpregs_active;
	extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get,
	xstateregs_get;
	extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set,
	xstateregs_set;

	/*
	* xstateregs_active == fpregs_active. Please refer to the comment
	* at the definition of fpregs_active.
	*/
	#define xstateregs_active fpregs_active

	#ifdef CONFIG_MATH_EMULATION
	extern void finit_soft_fpu(struct i387_soft_struct *soft);
	#else
	static inline void finit_soft_fpu(struct i387_soft_struct *soft) {}
	#endif

	static inline int is_ia32_compat_frame(void)
	{
	return config_enabled(CONFIG_IA32_EMULATION) &&
	test_thread_flag(TIF_IA32);
	}

	static inline int is_ia32_frame(void)
	{
	return config_enabled(CONFIG_X86_32) \|\| is_ia32_compat_frame();
	}

	static inline int is_x32_frame(void)
	{
	return config_enabled(CONFIG_X86_X32_ABI) && test_thread_flag(TIF_X32);
	}

	#define X87_FSW_ES (1 << 7) /* Exception Summary */

	static __always_inline __pure bool use_eager_fpu(void)
	{
	return static_cpu_has_safe(X86_FEATURE_EAGER_FPU);
	}

	static __always_inline __pure bool use_xsaveopt(void)
	{
	return static_cpu_has_safe(X86_FEATURE_XSAVEOPT);
	}

	static __always_inline __pure bool use_xsave(void)
	{
	return static_cpu_has_safe(X86_FEATURE_XSAVE);
	}

	static __always_inline __pure bool use_fxsr(void)
	{
	return static_cpu_has_safe(X86_FEATURE_FXSR);
	}

	static inline void fx_finit(struct i387_fxsave_struct *fx)
	{
	memset(fx, 0, xstate_size);
	fx->cwd = 0x37f;
	fx->mxcsr = MXCSR_DEFAULT;
	}

	extern void __sanitize_i387_state(struct task_struct *);

	static inline void sanitize_i387_state(struct task_struct *tsk)
	{
	if (!use_xsaveopt())
	return;
	__sanitize_i387_state(tsk);
	}

	#define user_insn(insn, output, input...) \
	({ \
	int err; \
	asm volatile(ASM_STAC "\n" \
	"1:" #insn "\n\t" \
	"2: " ASM_CLAC "\n" \
	".section .fixup,\"ax\"\n" \
	"3: movl $-1,%[err]\n" \
	" jmp 2b\n" \
	".previous\n" \
	_ASM_EXTABLE(1b, 3b) \
	: [err] "=r" (err), output \
	: "0"(0), input); \
	err; \
	})

	#define check_insn(insn, output, input...) \
	({ \
	int err; \
	asm volatile("1:" #insn "\n\t" \
	"2:\n" \
	".section .fixup,\"ax\"\n" \
	"3: movl $-1,%[err]\n" \
	" jmp 2b\n" \
	".previous\n" \
	_ASM_EXTABLE(1b, 3b) \
	: [err] "=r" (err), output \
	: "0"(0), input); \
	err; \
	})

	static inline int fsave_user(struct i387_fsave_struct __user *fx)
	{
	return user_insn(fnsave %[fx]; fwait, [fx] "=m" (fx), "m" (fx));
	}

	static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
	{
	if (config_enabled(CONFIG_X86_32))
	return user_insn(fxsave %[fx], [fx] "=m" (fx), "m" (fx));
	else if (config_enabled(CONFIG_AS_FXSAVEQ))
	return user_insn(fxsaveq %[fx], [fx] "=m" (fx), "m" (fx));

	/* See comment in fpu_fxsave() below. */
	return user_insn(rex64/fxsave (%[fx]), "=m" (*fx), [fx] "R" (fx));
	}

	static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
	{
	if (config_enabled(CONFIG_X86_32))
	return check_insn(fxrstor %[fx], "=m" (fx), [fx] "m" (fx));
	else if (config_enabled(CONFIG_AS_FXSAVEQ))
	return check_insn(fxrstorq %[fx], "=m" (fx), [fx] "m" (fx));

	/* See comment in fpu_fxsave() below. */
	return check_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),
	"m" (*fx));
	}

	static inline int fxrstor_user(struct i387_fxsave_struct __user *fx)
	{
	if (config_enabled(CONFIG_X86_32))
	return user_insn(fxrstor %[fx], "=m" (fx), [fx] "m" (fx));
	else if (config_enabled(CONFIG_AS_FXSAVEQ))
	return user_insn(fxrstorq %[fx], "=m" (fx), [fx] "m" (fx));

	/* See comment in fpu_fxsave() below. */
	return user_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),
	"m" (*fx));
	}

	static inline int frstor_checking(struct i387_fsave_struct *fx)
	{
	return check_insn(frstor %[fx], "=m" (fx), [fx] "m" (fx));
	}

	static inline int frstor_user(struct i387_fsave_struct __user *fx)
	{
	return user_insn(frstor %[fx], "=m" (fx), [fx] "m" (fx));
	}

	static inline void fpu_fxsave(struct fpu *fpu)
	{
	if (config_enabled(CONFIG_X86_32))
	asm volatile( "fxsave %[fx]" : [fx] "=m" (fpu->state->fxsave));
	else if (config_enabled(CONFIG_AS_FXSAVEQ))
	asm volatile("fxsaveq %0" : "=m" (fpu->state->fxsave));
	else {
	/* 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.
	*
	* Using "fxsaveq %0" would be the ideal choice, but is only
	* supported starting with gas 2.16.
	*
	* 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));
	*
	* 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 (%[fx])"
	: "=m" (fpu->state->fxsave)
	: [fx] "R" (&fpu->state->fxsave));
	}
	}

	/*
	* These must be called with preempt disabled. Returns
	* 'true' if the FPU state is still intact.
	*/
	static inline int fpu_save_init(struct fpu *fpu)
	{
	if (use_xsave()) {
	fpu_xsave(fpu);

	/*
	* xsave header may indicate the init state of the FP.
	*/
	if (!(fpu->state->xsave.xsave_hdr.xstate_bv & XSTATE_FP))
	return 1;
	} else if (use_fxsr()) {
	fpu_fxsave(fpu);
	} else {
	asm volatile("fnsave %[fx]; fwait"
	: [fx] "=m" (fpu->state->fsave));
	return 0;
	}

	/*
	* If exceptions are pending, we need to clear them so
	* that we don't randomly get exceptions later.
	*
	* FIXME! Is this perhaps only true for the old-style
	* irq13 case? Maybe we could leave the x87 state
	* intact otherwise?
	*/
	if (unlikely(fpu->state->fxsave.swd & X87_FSW_ES)) {
	asm volatile("fnclex");
	return 0;
	}
	return 1;
	}

	static inline int __save_init_fpu(struct task_struct *tsk)
	{
	return fpu_save_init(&tsk->thread.fpu);
	}

	static inline int fpu_restore_checking(struct fpu *fpu)
	{
	if (use_xsave())
	return fpu_xrstor_checking(&fpu->state->xsave);
	else if (use_fxsr())
	return fxrstor_checking(&fpu->state->fxsave);
	else
	return frstor_checking(&fpu->state->fsave);
	}

	static inline int restore_fpu_checking(struct task_struct *tsk)
	{
	/* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception
	is pending. Clear the x87 state here by setting it to fixed
	values. "m" is a random variable that should be in L1 */
	if (unlikely(static_cpu_has_bug_safe(X86_BUG_FXSAVE_LEAK))) {
	asm volatile(
	"fnclex\n\t"
	"emms\n\t"
	"fildl %P[addr]" /* set F?P to defined value */
	: : [addr] "m" (tsk->thread.fpu.has_fpu));
	}

	return fpu_restore_checking(&tsk->thread.fpu);
	}

	/*
	* Software FPU state helpers. Careful: these need to
	* be preemption protection and they need to be
	* properly paired with the CR0.TS changes!
	*/
	static inline int __thread_has_fpu(struct task_struct *tsk)
	{
	return tsk->thread.fpu.has_fpu;
	}

	/* Must be paired with an 'stts' after! */
	static inline void __thread_clear_has_fpu(struct task_struct *tsk)
	{
	tsk->thread.fpu.has_fpu = 0;
	this_cpu_write(fpu_owner_task, NULL);
	}

	/* Must be paired with a 'clts' before! */
	static inline void __thread_set_has_fpu(struct task_struct *tsk)
	{
	tsk->thread.fpu.has_fpu = 1;
	this_cpu_write(fpu_owner_task, tsk);
	}

	/*
	* Encapsulate the CR0.TS handling together with the
	* software flag.
	*
	* These generally need preemption protection to work,
	* do try to avoid using these on their own.
	*/
	static inline void __thread_fpu_end(struct task_struct *tsk)
	{
	__thread_clear_has_fpu(tsk);
	if (!use_eager_fpu())
	stts();
	}

	static inline void __thread_fpu_begin(struct task_struct *tsk)
	{
	if (!static_cpu_has_safe(X86_FEATURE_EAGER_FPU))
	clts();
	__thread_set_has_fpu(tsk);
	}

	static inline void __drop_fpu(struct task_struct *tsk)
	{
	if (__thread_has_fpu(tsk)) {
	/* Ignore delayed exceptions from user space */
	asm volatile("1: fwait\n"
	"2:\n"
	_ASM_EXTABLE(1b, 2b));
	__thread_fpu_end(tsk);
	}
	}

	static inline void drop_fpu(struct task_struct *tsk)
	{
	/*
	* Forget coprocessor state..
	*/
	preempt_disable();
	tsk->thread.fpu_counter = 0;
	__drop_fpu(tsk);
	clear_used_math();
	preempt_enable();
	}

	static inline void drop_init_fpu(struct task_struct *tsk)
	{
	if (!use_eager_fpu())
	drop_fpu(tsk);
	else {
	if (use_xsave())
	xrstor_state(init_xstate_buf, -1);
	else
	fxrstor_checking(&init_xstate_buf->i387);
	}
	}

	/*
	* FPU state switching for scheduling.
	*
	* This is a two-stage process:
	*
	* - switch_fpu_prepare() saves the old state and
	* sets the new state of the CR0.TS bit. This is
	* done within the context of the old process.
	*
	* - switch_fpu_finish() restores the new state as
	* necessary.
	*/
	typedef struct { int preload; } fpu_switch_t;

	/*
	* Must be run with preemption disabled: this clears the fpu_owner_task,
	* on this CPU.
	*
	* This will disable any lazy FPU state restore of the current FPU state,
	* but if the current thread owns the FPU, it will still be saved by.
	*/
	static inline void __cpu_disable_lazy_restore(unsigned int cpu)
	{
	per_cpu(fpu_owner_task, cpu) = NULL;
	}

	static inline int fpu_lazy_restore(struct task_struct *new, unsigned int cpu)
	{
	return new == this_cpu_read_stable(fpu_owner_task) &&
	cpu == new->thread.fpu.last_cpu;
	}

	static inline fpu_switch_t switch_fpu_prepare(struct task_struct old, struct task_struct new, int cpu)
	{
	fpu_switch_t fpu;

	/*
	* If the task has used the math, pre-load the FPU on xsave processors
	* or if the past 5 consecutive context-switches used math.
	*/
	fpu.preload = tsk_used_math(new) && (use_eager_fpu() \|\|
	new->thread.fpu_counter > 5);
	if (__thread_has_fpu(old)) {
	if (!__save_init_fpu(old))
	cpu = ~0;
	old->thread.fpu.last_cpu = cpu;
	old->thread.fpu.has_fpu = 0; /* But leave fpu_owner_task! */

	/* Don't change CR0.TS if we just switch! */
	if (fpu.preload) {
	new->thread.fpu_counter++;
	__thread_set_has_fpu(new);
	prefetch(new->thread.fpu.state);
	} else if (!use_eager_fpu())
	stts();
	} else {
	old->thread.fpu_counter = 0;
	old->thread.fpu.last_cpu = ~0;
	if (fpu.preload) {
	new->thread.fpu_counter++;
	if (!use_eager_fpu() && fpu_lazy_restore(new, cpu))
	fpu.preload = 0;
	else
	prefetch(new->thread.fpu.state);
	__thread_fpu_begin(new);
	}
	}
	return fpu;
	}

	/*
	* By the time this gets called, we've already cleared CR0.TS and
	* given the process the FPU if we are going to preload the FPU
	* state - all we need to do is to conditionally restore the register
	* state itself.
	*/
	static inline void switch_fpu_finish(struct task_struct *new, fpu_switch_t fpu)
	{
	if (fpu.preload) {
	if (unlikely(restore_fpu_checking(new)))
	drop_init_fpu(new);
	}
	}

	/*
	* Signal frame handlers...
	*/
	extern int save_xstate_sig(void __user buf, void __user fx, int size);
	extern int __restore_xstate_sig(void __user buf, void __user fx, int size);

	static inline int xstate_sigframe_size(void)
	{
	return use_xsave() ? xstate_size + FP_XSTATE_MAGIC2_SIZE : xstate_size;
	}

	static inline int restore_xstate_sig(void __user *buf, int ia32_frame)
	{
	void __user *buf_fx = buf;
	int size = xstate_sigframe_size();

	if (ia32_frame && use_fxsr()) {
	buf_fx = buf + sizeof(struct i387_fsave_struct);
	size += sizeof(struct i387_fsave_struct);
	}

	return __restore_xstate_sig(buf, buf_fx, size);
	}

	/*
	* Need to be preemption-safe.
	*
	* NOTE! user_fpu_begin() must be used only immediately before restoring
	* it. This function does not do any save/restore on their own.
	*/
	static inline void user_fpu_begin(void)
	{
	preempt_disable();
	if (!user_has_fpu())
	__thread_fpu_begin(current);
	preempt_enable();
	}

	static inline void __save_fpu(struct task_struct *tsk)
	{
	if (use_xsave()) {
	if (unlikely(system_state == SYSTEM_BOOTING))
	xsave_state_booting(&tsk->thread.fpu.state->xsave, -1);
	else
	xsave_state(&tsk->thread.fpu.state->xsave, -1);
	} else
	fpu_fxsave(&tsk->thread.fpu);
	}

	/*
	* These disable preemption on their own and are safe
	*/
	static inline void save_init_fpu(struct task_struct *tsk)
	{
	WARN_ON_ONCE(!__thread_has_fpu(tsk));

	if (use_eager_fpu()) {
	__save_fpu(tsk);
	return;
	}

	preempt_disable();
	__save_init_fpu(tsk);
	__thread_fpu_end(tsk);
	preempt_enable();
	}

	/*
	* i387 state interaction
	*/
	static inline unsigned short get_fpu_cwd(struct task_struct *tsk)
	{
	if (cpu_has_fxsr) {
	return tsk->thread.fpu.state->fxsave.cwd;
	} else {
	return (unsigned short)tsk->thread.fpu.state->fsave.cwd;
	}
	}

	static inline unsigned short get_fpu_swd(struct task_struct *tsk)
	{
	if (cpu_has_fxsr) {
	return tsk->thread.fpu.state->fxsave.swd;
	} else {
	return (unsigned short)tsk->thread.fpu.state->fsave.swd;
	}
	}

	static inline unsigned short get_fpu_mxcsr(struct task_struct *tsk)
	{
	if (cpu_has_xmm) {
	return tsk->thread.fpu.state->fxsave.mxcsr;
	} else {
	return MXCSR_DEFAULT;
	}
	}

	static bool fpu_allocated(struct fpu *fpu)
	{
	return fpu->state != NULL;
	}

	static inline int fpu_alloc(struct fpu *fpu)
	{
	if (fpu_allocated(fpu))
	return 0;
	fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL);
	if (!fpu->state)
	return -ENOMEM;
	WARN_ON((unsigned long)fpu->state & 15);
	return 0;
	}

	static inline void fpu_free(struct fpu *fpu)
	{
	if (fpu->state) {
	kmem_cache_free(task_xstate_cachep, fpu->state);
	fpu->state = NULL;
	}
	}

	static inline void fpu_copy(struct task_struct dst, struct task_struct src)
	{
	if (use_eager_fpu()) {
	memset(&dst->thread.fpu.state->xsave, 0, xstate_size);
	__save_fpu(dst);
	} else {
	struct fpu *dfpu = &dst->thread.fpu;
	struct fpu *sfpu = &src->thread.fpu;

	unlazy_fpu(src);
	memcpy(dfpu->state, sfpu->state, xstate_size);
	}
	}

	static inline unsigned long
	alloc_mathframe(unsigned long sp, int ia32_frame, unsigned long *buf_fx,
	unsigned long *size)
	{
	unsigned long frame_size = xstate_sigframe_size();

	*buf_fx = sp = round_down(sp - frame_size, 64);
	if (ia32_frame && use_fxsr()) {
	frame_size += sizeof(struct i387_fsave_struct);
	sp -= sizeof(struct i387_fsave_struct);
	}

	*size = frame_size;
	return sp;
	}

	#endif