arch/x86/include/asm/fpu/internal.h - kernel/bruno - 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 _ASM_X86_FPU_INTERNAL_H
 #define _ASM_X86_FPU_INTERNAL_H

 #include <linux/compat.h>
 #include <linux/sched.h>
 #include <linux/slab.h>

 #include <asm/user.h>
 #include <asm/fpu/api.h>
 #include <asm/fpu/xstate.h>

 /*
  * High level FPU state handling functions:
  */
 extern void fpu__activate_curr(struct fpu *fpu);
 extern void fpu__activate_fpstate_read(struct fpu *fpu);
 extern void fpu__activate_fpstate_write(struct fpu *fpu);
 extern void fpu__save(struct fpu *fpu);
 extern void fpu__restore(struct fpu *fpu);
 extern int  fpu__restore_sig(void __user *buf, int ia32_frame);
 extern void fpu__drop(struct fpu *fpu);
 extern int  fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu);
 extern void fpu__clear(struct fpu *fpu);
 extern int  fpu__exception_code(struct fpu *fpu, int trap_nr);
 extern int  dump_fpu(struct pt_regs *ptregs, struct user_i387_struct *fpstate);

 /*
  * Boot time FPU initialization functions:
  */
 extern void fpu__init_cpu(void);
 extern void fpu__init_system_xstate(void);
 extern void fpu__init_cpu_xstate(void);
 extern void fpu__init_system(struct cpuinfo_x86 *c);
 extern void fpu__init_check_bugs(void);
 extern void fpu__resume_cpu(void);

 /*
  * Debugging facility:
  */
 #ifdef CONFIG_X86_DEBUG_FPU
 # define WARN_ON_FPU(x) WARN_ON_ONCE(x)
 #else
 # define WARN_ON_FPU(x) ({ (void)(x); 0; })
 #endif

 /*
  * FPU related CPU feature flag helper routines:
  */
 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);
 }

 /*
  * fpstate handling functions:
  */

 extern union fpregs_state init_fpstate;

 extern void fpstate_init(union fpregs_state *state);
 #ifdef CONFIG_MATH_EMULATION
 extern void fpstate_init_soft(struct swregs_state *soft);
 #else
 static inline void fpstate_init_soft(struct swregs_state *soft) {}
 #endif
 static inline void fpstate_init_fxstate(struct fxregs_state *fx)
 {
 	fx->cwd = 0x37f;
 	fx->mxcsr = MXCSR_DEFAULT;
 }
 extern void fpstate_sanitize_xstate(struct fpu *fpu);

 #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 copy_fregs_to_user(struct fregs_state __user *fx)
 {
 	return user_insn(fnsave %[fx]; fwait,  [fx] "=m" (*fx), "m" (*fx));
 }

 static inline int copy_fxregs_to_user(struct fxregs_state __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 copy_fxregs_to_kernel() below. */
 	return user_insn(rex64/fxsave (%[fx]), "=m" (*fx), [fx] "R" (fx));
 }

 static inline void copy_kernel_to_fxregs(struct fxregs_state *fx)
 {
 	int err;

 	if (config_enabled(CONFIG_X86_32)) {
 		err = check_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
 	} else {
 		if (config_enabled(CONFIG_AS_FXSAVEQ)) {
 			err = check_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
 		} else {
 			/* See comment in copy_fxregs_to_kernel() below. */
 			err = check_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx), "m" (*fx));
 		}
 	}
 	/* Copying from a kernel buffer to FPU registers should never fail: */
 	WARN_ON_FPU(err);
 }

 static inline int copy_user_to_fxregs(struct fxregs_state __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 copy_fxregs_to_kernel() below. */
 	return user_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),
 			  "m" (*fx));
 }

 static inline void copy_kernel_to_fregs(struct fregs_state *fx)
 {
 	int err = check_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));

 	WARN_ON_FPU(err);
 }

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

 static inline void copy_fxregs_to_kernel(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 %[fx]" : [fx] "=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 macros all use (%edi)/(%rdi) as the single memory argument. */
 #define XSAVE		".byte " REX_PREFIX "0x0f,0xae,0x27"
 #define XSAVEOPT	".byte " REX_PREFIX "0x0f,0xae,0x37"
 #define XSAVES		".byte " REX_PREFIX "0x0f,0xc7,0x2f"
 #define XRSTOR		".byte " REX_PREFIX "0x0f,0xae,0x2f"
 #define XRSTORS		".byte " REX_PREFIX "0x0f,0xc7,0x1f"

 /* xstate instruction fault handler: */
 #define xstate_fault(__err)		\
 					\
 	".section .fixup,\"ax\"\n"	\
 					\
 	"3:  movl $-2,%[_err]\n"	\
 	"    jmp  2b\n"			\
 					\
 	".previous\n"			\
 					\
 	_ASM_EXTABLE(1b, 3b)		\
 	: [_err] "=r" (__err)

 /*
  * This function is called only during boot time when x86 caps are not set
  * up and alternative can not be used yet.
  */
 static inline void copy_xregs_to_kernel_booting(struct xregs_state *xstate)
 {
 	u64 mask = -1;
 	u32 lmask = mask;
 	u32 hmask = mask >> 32;
 	int err = 0;

 	WARN_ON(system_state != SYSTEM_BOOTING);

 	if (boot_cpu_has(X86_FEATURE_XSAVES))
 		asm volatile("1:"XSAVES"\n\t"
 			"2:\n\t"
 			     xstate_fault(err)
 			: "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
 			: "memory");
 	else
 		asm volatile("1:"XSAVE"\n\t"
 			"2:\n\t"
 			     xstate_fault(err)
 			: "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
 			: "memory");

 	/* We should never fault when copying to a kernel buffer: */
 	WARN_ON_FPU(err);
 }

 /*
  * This function is called only during boot time when x86 caps are not set
  * up and alternative can not be used yet.
  */
 static inline void copy_kernel_to_xregs_booting(struct xregs_state *xstate)
 {
 	u64 mask = -1;
 	u32 lmask = mask;
 	u32 hmask = mask >> 32;
 	int err = 0;

 	WARN_ON(system_state != SYSTEM_BOOTING);

 	if (boot_cpu_has(X86_FEATURE_XSAVES))
 		asm volatile("1:"XRSTORS"\n\t"
 			"2:\n\t"
 			     xstate_fault(err)
 			: "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
 			: "memory");
 	else
 		asm volatile("1:"XRSTOR"\n\t"
 			"2:\n\t"
 			     xstate_fault(err)
 			: "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
 			: "memory");

 	/* We should never fault when copying from a kernel buffer: */
 	WARN_ON_FPU(err);
 }

 /*
  * Save processor xstate to xsave area.
  */
 static inline void copy_xregs_to_kernel(struct xregs_state *xstate)
 {
 	u64 mask = -1;
 	u32 lmask = mask;
 	u32 hmask = mask >> 32;
 	int err = 0;

 	WARN_ON(!alternatives_patched);

 	/*
 	 * If xsaves is enabled, xsaves replaces xsaveopt because
 	 * it supports compact format and supervisor states in addition to
 	 * modified optimization in xsaveopt.
 	 *
 	 * Otherwise, if xsaveopt is enabled, xsaveopt replaces xsave
 	 * because xsaveopt supports modified optimization which is not
 	 * supported by xsave.
 	 *
 	 * If none of xsaves and xsaveopt is enabled, use xsave.
 	 */
 	alternative_input_2(
 		"1:"XSAVE,
 		XSAVEOPT,
 		X86_FEATURE_XSAVEOPT,
 		XSAVES,
 		X86_FEATURE_XSAVES,
 		[xstate] "D" (xstate), "a" (lmask), "d" (hmask) :
 		"memory");
 	asm volatile("2:\n\t"
 		     xstate_fault(err)
 		     : "0" (err)
 		     : "memory");

 	/* We should never fault when copying to a kernel buffer: */
 	WARN_ON_FPU(err);
 }

 /*
  * Restore processor xstate from xsave area.
  */
 static inline void copy_kernel_to_xregs(struct xregs_state *xstate, u64 mask)
 {
 	u32 lmask = mask;
 	u32 hmask = mask >> 32;
 	int err = 0;

 	/*
 	 * Use xrstors to restore context if it is enabled. xrstors supports
 	 * compacted format of xsave area which is not supported by xrstor.
 	 */
 	alternative_input(
 		"1: " XRSTOR,
 		XRSTORS,
 		X86_FEATURE_XSAVES,
 		"D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask)
 		: "memory");

 	asm volatile("2:\n"
 		     xstate_fault(err)
 		     : "0" (err)
 		     : "memory");

 	/* We should never fault when copying from a kernel buffer: */
 	WARN_ON_FPU(err);
 }

 /*
  * Save xstate to user space xsave area.
  *
  * We don't use modified optimization because xrstor/xrstors might track
  * a different application.
  *
  * We don't use compacted format xsave area for
  * backward compatibility for old applications which don't understand
  * compacted format of xsave area.
  */
 static inline int copy_xregs_to_user(struct xregs_state __user *buf)
 {
 	int err;

 	/*
 	 * Clear the xsave header first, so that reserved fields are
 	 * initialized to zero.
 	 */
 	err = __clear_user(&buf->header, sizeof(buf->header));
 	if (unlikely(err))
 		return -EFAULT;

 	__asm__ __volatile__(ASM_STAC "\n"
 			     "1:"XSAVE"\n"
 			     "2: " ASM_CLAC "\n"
 			     xstate_fault(err)
 			     : "D" (buf), "a" (-1), "d" (-1), "0" (err)
 			     : "memory");
 	return err;
 }

 /*
  * Restore xstate from user space xsave area.
  */
 static inline int copy_user_to_xregs(struct xregs_state __user *buf, u64 mask)
 {
 	struct xregs_state *xstate = ((__force struct xregs_state *)buf);
 	u32 lmask = mask;
 	u32 hmask = mask >> 32;
 	int err = 0;

 	__asm__ __volatile__(ASM_STAC "\n"
 			     "1:"XRSTOR"\n"
 			     "2: " ASM_CLAC "\n"
 			     xstate_fault(err)
 			     : "D" (xstate), "a" (lmask), "d" (hmask), "0" (err)
 			     : "memory");	/* memory required? */
 	return err;
 }

 /*
  * These must be called with preempt disabled. Returns
  * 'true' if the FPU state is still intact and we can
  * keep registers active.
  *
  * The legacy FNSAVE instruction cleared all FPU state
  * unconditionally, so registers are essentially destroyed.
  * Modern FPU state can be kept in registers, if there are
  * no pending FP exceptions.
  */
 static inline int copy_fpregs_to_fpstate(struct fpu *fpu)
 {
 	if (likely(use_xsave())) {
 		copy_xregs_to_kernel(&fpu->state.xsave);
 		return 1;
 	}

 	if (likely(use_fxsr())) {
 		copy_fxregs_to_kernel(fpu);
 		return 1;
 	}

 	/*
 	 * Legacy FPU register saving, FNSAVE always clears FPU registers,
 	 * so we have to mark them inactive:
 	 */
 	asm volatile("fnsave %[fp]; fwait" : [fp] "=m" (fpu->state.fsave));

 	return 0;
 }

 static inline void __copy_kernel_to_fpregs(union fpregs_state *fpstate)
 {
 	if (use_xsave()) {
 		copy_kernel_to_xregs(&fpstate->xsave, -1);
 	} else {
 		if (use_fxsr())
 			copy_kernel_to_fxregs(&fpstate->fxsave);
 		else
 			copy_kernel_to_fregs(&fpstate->fsave);
 	}
 }

 static inline void copy_kernel_to_fpregs(union fpregs_state *fpstate)
 {
 	/*
 	 * 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" (fpstate));
 	}

 	__copy_kernel_to_fpregs(fpstate);
 }

 extern int copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size);

 /*
  * FPU context switch related helper methods:
  */

 DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx);

 /*
  * Must be run with preemption disabled: this clears the fpu_fpregs_owner_ctx,
  * 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_fpregs_owner_ctx, cpu) = NULL;
 }

 static inline int fpu_want_lazy_restore(struct fpu *fpu, unsigned int cpu)
 {
 	return fpu == this_cpu_read_stable(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
 }


 /*
  * Wrap lazy FPU TS handling in a 'hw fpregs activation/deactivation'
  * idiom, which is then paired with the sw-flag (fpregs_active) later on:
  */

 static inline void __fpregs_activate_hw(void)
 {
 	if (!use_eager_fpu())
 		clts();
 }

 static inline void __fpregs_deactivate_hw(void)
 {
 	if (!use_eager_fpu())
 		stts();
 }

 /* Must be paired with an 'stts' (fpregs_deactivate_hw()) after! */
 static inline void __fpregs_deactivate(struct fpu *fpu)
 {
 	WARN_ON_FPU(!fpu->fpregs_active);

 	fpu->fpregs_active = 0;
 	this_cpu_write(fpu_fpregs_owner_ctx, NULL);
 }

 /* Must be paired with a 'clts' (fpregs_activate_hw()) before! */
 static inline void __fpregs_activate(struct fpu *fpu)
 {
 	WARN_ON_FPU(fpu->fpregs_active);

 	fpu->fpregs_active = 1;
 	this_cpu_write(fpu_fpregs_owner_ctx, fpu);
 }

 /*
  * The question "does this thread have fpu access?"
  * is slightly racy, since preemption could come in
  * and revoke it immediately after the test.
  *
  * However, even in that very unlikely scenario,
  * we can just assume we have FPU access - typically
  * to save the FP state - we'll just take a #NM
  * fault and get the FPU access back.
  */
 static inline int fpregs_active(void)
 {
 	return current->thread.fpu.fpregs_active;
 }

 /*
  * 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 fpregs_activate(struct fpu *fpu)
 {
 	__fpregs_activate_hw();
 	__fpregs_activate(fpu);
 }

 static inline void fpregs_deactivate(struct fpu *fpu)
 {
 	__fpregs_deactivate(fpu);
 	__fpregs_deactivate_hw();
 }

 /*
  * 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;

 static inline fpu_switch_t
 switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, 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 = new_fpu->fpstate_active &&
 		      (use_eager_fpu() || new_fpu->counter > 5);

 	if (old_fpu->fpregs_active) {
 		if (!copy_fpregs_to_fpstate(old_fpu))
 			old_fpu->last_cpu = -1;
 		else
 			old_fpu->last_cpu = cpu;

 		/* But leave fpu_fpregs_owner_ctx! */
 		old_fpu->fpregs_active = 0;

 		/* Don't change CR0.TS if we just switch! */
 		if (fpu.preload) {
 			new_fpu->counter++;
 			__fpregs_activate(new_fpu);
 			prefetch(&new_fpu->state);
 		} else {
 			__fpregs_deactivate_hw();
 		}
 	} else {
 		old_fpu->counter = 0;
 		old_fpu->last_cpu = -1;
 		if (fpu.preload) {
 			new_fpu->counter++;
 			if (fpu_want_lazy_restore(new_fpu, cpu))
 				fpu.preload = 0;
 			else
 				prefetch(&new_fpu->state);
 			fpregs_activate(new_fpu);
 		}
 	}
 	return fpu;
 }

 /*
  * Misc helper functions:
  */

 /*
  * 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 fpu *new_fpu, fpu_switch_t fpu_switch)
 {
 	if (fpu_switch.preload)
 		copy_kernel_to_fpregs(&new_fpu->state);
 }

 /*
  * Needs to be preemption-safe.
  *
  * NOTE! user_fpu_begin() must be used only immediately before restoring
  * the save state. It does not do any saving/restoring on its own. In
  * lazy FPU mode, it is just an optimization to avoid a #NM exception,
  * the task can lose the FPU right after preempt_enable().
  */
 static inline void user_fpu_begin(void)
 {
 	struct fpu *fpu = &current->thread.fpu;

 	preempt_disable();
 	if (!fpregs_active())
 		fpregs_activate(fpu);
 	preempt_enable();
 }

 /*
  * MXCSR and XCR definitions:
  */

 extern unsigned int mxcsr_feature_mask;

 #define XCR_XFEATURE_ENABLED_MASK	0x00000000

 static inline u64 xgetbv(u32 index)
 {
 	u32 eax, edx;

 	asm volatile(".byte 0x0f,0x01,0xd0" /* xgetbv */
 		     : "=a" (eax), "=d" (edx)
 		     : "c" (index));
 	return eax + ((u64)edx << 32);
 }

 static inline void xsetbv(u32 index, u64 value)
 {
 	u32 eax = value;
 	u32 edx = value >> 32;

 	asm volatile(".byte 0x0f,0x01,0xd1" /* xsetbv */
 		     : : "a" (eax), "d" (edx), "c" (index));
 }

 #endif /* _ASM_X86_FPU_INTERNAL_H */
	/*
	* 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 _ASM_X86_FPU_INTERNAL_H
	#define _ASM_X86_FPU_INTERNAL_H

	#include <linux/compat.h>
	#include <linux/sched.h>
	#include <linux/slab.h>

	#include <asm/user.h>
	#include <asm/fpu/api.h>
	#include <asm/fpu/xstate.h>

	/*
	* High level FPU state handling functions:
	*/
	extern void fpu__activate_curr(struct fpu *fpu);
	extern void fpu__activate_fpstate_read(struct fpu *fpu);
	extern void fpu__activate_fpstate_write(struct fpu *fpu);
	extern void fpu__save(struct fpu *fpu);
	extern void fpu__restore(struct fpu *fpu);
	extern int fpu__restore_sig(void __user *buf, int ia32_frame);
	extern void fpu__drop(struct fpu *fpu);
	extern int fpu__copy(struct fpu dst_fpu, struct fpu src_fpu);
	extern void fpu__clear(struct fpu *fpu);
	extern int fpu__exception_code(struct fpu *fpu, int trap_nr);
	extern int dump_fpu(struct pt_regs ptregs, struct user_i387_struct fpstate);

	/*
	* Boot time FPU initialization functions:
	*/
	extern void fpu__init_cpu(void);
	extern void fpu__init_system_xstate(void);
	extern void fpu__init_cpu_xstate(void);
	extern void fpu__init_system(struct cpuinfo_x86 *c);
	extern void fpu__init_check_bugs(void);
	extern void fpu__resume_cpu(void);

	/*
	* Debugging facility:
	*/
	#ifdef CONFIG_X86_DEBUG_FPU
	# define WARN_ON_FPU(x) WARN_ON_ONCE(x)
	#else
	# define WARN_ON_FPU(x) ({ (void)(x); 0; })
	#endif

	/*
	* FPU related CPU feature flag helper routines:
	*/
	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);
	}

	/*
	* fpstate handling functions:
	*/

	extern union fpregs_state init_fpstate;

	extern void fpstate_init(union fpregs_state *state);
	#ifdef CONFIG_MATH_EMULATION
	extern void fpstate_init_soft(struct swregs_state *soft);
	#else
	static inline void fpstate_init_soft(struct swregs_state *soft) {}
	#endif
	static inline void fpstate_init_fxstate(struct fxregs_state *fx)
	{
	fx->cwd = 0x37f;
	fx->mxcsr = MXCSR_DEFAULT;
	}
	extern void fpstate_sanitize_xstate(struct fpu *fpu);

	#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 copy_fregs_to_user(struct fregs_state __user *fx)
	{
	return user_insn(fnsave %[fx]; fwait, [fx] "=m" (fx), "m" (fx));
	}

	static inline int copy_fxregs_to_user(struct fxregs_state __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 copy_fxregs_to_kernel() below. */
	return user_insn(rex64/fxsave (%[fx]), "=m" (*fx), [fx] "R" (fx));
	}

	static inline void copy_kernel_to_fxregs(struct fxregs_state *fx)
	{
	int err;

	if (config_enabled(CONFIG_X86_32)) {
	err = check_insn(fxrstor %[fx], "=m" (fx), [fx] "m" (fx));
	} else {
	if (config_enabled(CONFIG_AS_FXSAVEQ)) {
	err = check_insn(fxrstorq %[fx], "=m" (fx), [fx] "m" (fx));
	} else {
	/* See comment in copy_fxregs_to_kernel() below. */
	err = check_insn(rex64/fxrstor (%[fx]), "=m" (fx), [fx] "R" (fx), "m" (fx));
	}
	}
	/* Copying from a kernel buffer to FPU registers should never fail: */
	WARN_ON_FPU(err);
	}

	static inline int copy_user_to_fxregs(struct fxregs_state __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 copy_fxregs_to_kernel() below. */
	return user_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),
	"m" (*fx));
	}

	static inline void copy_kernel_to_fregs(struct fregs_state *fx)
	{
	int err = check_insn(frstor %[fx], "=m" (fx), [fx] "m" (fx));

	WARN_ON_FPU(err);
	}

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

	static inline void copy_fxregs_to_kernel(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 %[fx]" : [fx] "=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 macros all use (%edi)/(%rdi) as the single memory argument. */
	#define XSAVE ".byte " REX_PREFIX "0x0f,0xae,0x27"
	#define XSAVEOPT ".byte " REX_PREFIX "0x0f,0xae,0x37"
	#define XSAVES ".byte " REX_PREFIX "0x0f,0xc7,0x2f"
	#define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f"
	#define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f"

	/* xstate instruction fault handler: */
	#define xstate_fault(__err) \
	\
	".section .fixup,\"ax\"\n" \
	\
	"3: movl $-2,%[_err]\n" \
	" jmp 2b\n" \
	\
	".previous\n" \
	\
	_ASM_EXTABLE(1b, 3b) \
	: [_err] "=r" (__err)

	/*
	* This function is called only during boot time when x86 caps are not set
	* up and alternative can not be used yet.
	*/
	static inline void copy_xregs_to_kernel_booting(struct xregs_state *xstate)
	{
	u64 mask = -1;
	u32 lmask = mask;
	u32 hmask = mask >> 32;
	int err = 0;

	WARN_ON(system_state != SYSTEM_BOOTING);

	if (boot_cpu_has(X86_FEATURE_XSAVES))
	asm volatile("1:"XSAVES"\n\t"
	"2:\n\t"
	xstate_fault(err)
	: "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
	: "memory");
	else
	asm volatile("1:"XSAVE"\n\t"
	"2:\n\t"
	xstate_fault(err)
	: "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
	: "memory");

	/* We should never fault when copying to a kernel buffer: */
	WARN_ON_FPU(err);
	}

	/*
	* This function is called only during boot time when x86 caps are not set
	* up and alternative can not be used yet.
	*/
	static inline void copy_kernel_to_xregs_booting(struct xregs_state *xstate)
	{
	u64 mask = -1;
	u32 lmask = mask;
	u32 hmask = mask >> 32;
	int err = 0;

	WARN_ON(system_state != SYSTEM_BOOTING);

	if (boot_cpu_has(X86_FEATURE_XSAVES))
	asm volatile("1:"XRSTORS"\n\t"
	"2:\n\t"
	xstate_fault(err)
	: "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
	: "memory");
	else
	asm volatile("1:"XRSTOR"\n\t"
	"2:\n\t"
	xstate_fault(err)
	: "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err)
	: "memory");

	/* We should never fault when copying from a kernel buffer: */
	WARN_ON_FPU(err);
	}

	/*
	* Save processor xstate to xsave area.
	*/
	static inline void copy_xregs_to_kernel(struct xregs_state *xstate)
	{
	u64 mask = -1;
	u32 lmask = mask;
	u32 hmask = mask >> 32;
	int err = 0;

	WARN_ON(!alternatives_patched);

	/*
	* If xsaves is enabled, xsaves replaces xsaveopt because
	* it supports compact format and supervisor states in addition to
	* modified optimization in xsaveopt.
	*
	* Otherwise, if xsaveopt is enabled, xsaveopt replaces xsave
	* because xsaveopt supports modified optimization which is not
	* supported by xsave.
	*
	* If none of xsaves and xsaveopt is enabled, use xsave.
	*/
	alternative_input_2(
	"1:"XSAVE,
	XSAVEOPT,
	X86_FEATURE_XSAVEOPT,
	XSAVES,
	X86_FEATURE_XSAVES,
	[xstate] "D" (xstate), "a" (lmask), "d" (hmask) :
	"memory");
	asm volatile("2:\n\t"
	xstate_fault(err)
	: "0" (err)
	: "memory");

	/* We should never fault when copying to a kernel buffer: */
	WARN_ON_FPU(err);
	}

	/*
	* Restore processor xstate from xsave area.
	*/
	static inline void copy_kernel_to_xregs(struct xregs_state *xstate, u64 mask)
	{
	u32 lmask = mask;
	u32 hmask = mask >> 32;
	int err = 0;

	/*
	* Use xrstors to restore context if it is enabled. xrstors supports
	* compacted format of xsave area which is not supported by xrstor.
	*/
	alternative_input(
	"1: " XRSTOR,
	XRSTORS,
	X86_FEATURE_XSAVES,
	"D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask)
	: "memory");

	asm volatile("2:\n"
	xstate_fault(err)
	: "0" (err)
	: "memory");

	/* We should never fault when copying from a kernel buffer: */
	WARN_ON_FPU(err);
	}

	/*
	* Save xstate to user space xsave area.
	*
	* We don't use modified optimization because xrstor/xrstors might track
	* a different application.
	*
	* We don't use compacted format xsave area for
	* backward compatibility for old applications which don't understand
	* compacted format of xsave area.
	*/
	static inline int copy_xregs_to_user(struct xregs_state __user *buf)
	{
	int err;

	/*
	* Clear the xsave header first, so that reserved fields are
	* initialized to zero.
	*/
	err = __clear_user(&buf->header, sizeof(buf->header));
	if (unlikely(err))
	return -EFAULT;

	__asm__ __volatile__(ASM_STAC "\n"
	"1:"XSAVE"\n"
	"2: " ASM_CLAC "\n"
	xstate_fault(err)
	: "D" (buf), "a" (-1), "d" (-1), "0" (err)
	: "memory");
	return err;
	}

	/*
	* Restore xstate from user space xsave area.
	*/
	static inline int copy_user_to_xregs(struct xregs_state __user *buf, u64 mask)
	{
	struct xregs_state xstate = ((__force struct xregs_state )buf);
	u32 lmask = mask;
	u32 hmask = mask >> 32;
	int err = 0;

	__asm__ __volatile__(ASM_STAC "\n"
	"1:"XRSTOR"\n"
	"2: " ASM_CLAC "\n"
	xstate_fault(err)
	: "D" (xstate), "a" (lmask), "d" (hmask), "0" (err)
	: "memory"); /* memory required? */
	return err;
	}

	/*
	* These must be called with preempt disabled. Returns
	* 'true' if the FPU state is still intact and we can
	* keep registers active.
	*
	* The legacy FNSAVE instruction cleared all FPU state
	* unconditionally, so registers are essentially destroyed.
	* Modern FPU state can be kept in registers, if there are
	* no pending FP exceptions.
	*/
	static inline int copy_fpregs_to_fpstate(struct fpu *fpu)
	{
	if (likely(use_xsave())) {
	copy_xregs_to_kernel(&fpu->state.xsave);
	return 1;
	}

	if (likely(use_fxsr())) {
	copy_fxregs_to_kernel(fpu);
	return 1;
	}

	/*
	* Legacy FPU register saving, FNSAVE always clears FPU registers,
	* so we have to mark them inactive:
	*/
	asm volatile("fnsave %[fp]; fwait" : [fp] "=m" (fpu->state.fsave));

	return 0;
	}

	static inline void __copy_kernel_to_fpregs(union fpregs_state *fpstate)
	{
	if (use_xsave()) {
	copy_kernel_to_xregs(&fpstate->xsave, -1);
	} else {
	if (use_fxsr())
	copy_kernel_to_fxregs(&fpstate->fxsave);
	else
	copy_kernel_to_fregs(&fpstate->fsave);
	}
	}

	static inline void copy_kernel_to_fpregs(union fpregs_state *fpstate)
	{
	/*
	* 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" (fpstate));
	}

	__copy_kernel_to_fpregs(fpstate);
	}

	extern int copy_fpstate_to_sigframe(void __user buf, void __user fp, int size);

	/*
	* FPU context switch related helper methods:
	*/

	DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx);

	/*
	* Must be run with preemption disabled: this clears the fpu_fpregs_owner_ctx,
	* 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_fpregs_owner_ctx, cpu) = NULL;
	}

	static inline int fpu_want_lazy_restore(struct fpu *fpu, unsigned int cpu)
	{
	return fpu == this_cpu_read_stable(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
	}


	/*
	* Wrap lazy FPU TS handling in a 'hw fpregs activation/deactivation'
	* idiom, which is then paired with the sw-flag (fpregs_active) later on:
	*/

	static inline void __fpregs_activate_hw(void)
	{
	if (!use_eager_fpu())
	clts();
	}

	static inline void __fpregs_deactivate_hw(void)
	{
	if (!use_eager_fpu())
	stts();
	}

	/* Must be paired with an 'stts' (fpregs_deactivate_hw()) after! */
	static inline void __fpregs_deactivate(struct fpu *fpu)
	{
	WARN_ON_FPU(!fpu->fpregs_active);

	fpu->fpregs_active = 0;
	this_cpu_write(fpu_fpregs_owner_ctx, NULL);
	}

	/* Must be paired with a 'clts' (fpregs_activate_hw()) before! */
	static inline void __fpregs_activate(struct fpu *fpu)
	{
	WARN_ON_FPU(fpu->fpregs_active);

	fpu->fpregs_active = 1;
	this_cpu_write(fpu_fpregs_owner_ctx, fpu);
	}

	/*
	* The question "does this thread have fpu access?"
	* is slightly racy, since preemption could come in
	* and revoke it immediately after the test.
	*
	* However, even in that very unlikely scenario,
	* we can just assume we have FPU access - typically
	* to save the FP state - we'll just take a #NM
	* fault and get the FPU access back.
	*/
	static inline int fpregs_active(void)
	{
	return current->thread.fpu.fpregs_active;
	}

	/*
	* 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 fpregs_activate(struct fpu *fpu)
	{
	__fpregs_activate_hw();
	__fpregs_activate(fpu);
	}

	static inline void fpregs_deactivate(struct fpu *fpu)
	{
	__fpregs_deactivate(fpu);
	__fpregs_deactivate_hw();
	}

	/*
	* 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;

	static inline fpu_switch_t
	switch_fpu_prepare(struct fpu old_fpu, struct fpu new_fpu, 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 = new_fpu->fpstate_active &&
	(use_eager_fpu() \|\| new_fpu->counter > 5);

	if (old_fpu->fpregs_active) {
	if (!copy_fpregs_to_fpstate(old_fpu))
	old_fpu->last_cpu = -1;
	else
	old_fpu->last_cpu = cpu;

	/* But leave fpu_fpregs_owner_ctx! */
	old_fpu->fpregs_active = 0;

	/* Don't change CR0.TS if we just switch! */
	if (fpu.preload) {
	new_fpu->counter++;
	__fpregs_activate(new_fpu);
	prefetch(&new_fpu->state);
	} else {
	__fpregs_deactivate_hw();
	}
	} else {
	old_fpu->counter = 0;
	old_fpu->last_cpu = -1;
	if (fpu.preload) {
	new_fpu->counter++;
	if (fpu_want_lazy_restore(new_fpu, cpu))
	fpu.preload = 0;
	else
	prefetch(&new_fpu->state);
	fpregs_activate(new_fpu);
	}
	}
	return fpu;
	}

	/*
	* Misc helper functions:
	*/

	/*
	* 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 fpu *new_fpu, fpu_switch_t fpu_switch)
	{
	if (fpu_switch.preload)
	copy_kernel_to_fpregs(&new_fpu->state);
	}

	/*
	* Needs to be preemption-safe.
	*
	* NOTE! user_fpu_begin() must be used only immediately before restoring
	* the save state. It does not do any saving/restoring on its own. In
	* lazy FPU mode, it is just an optimization to avoid a #NM exception,
	* the task can lose the FPU right after preempt_enable().
	*/
	static inline void user_fpu_begin(void)
	{
	struct fpu *fpu = &current->thread.fpu;

	preempt_disable();
	if (!fpregs_active())
	fpregs_activate(fpu);
	preempt_enable();
	}

	/*
	* MXCSR and XCR definitions:
	*/

	extern unsigned int mxcsr_feature_mask;

	#define XCR_XFEATURE_ENABLED_MASK 0x00000000

	static inline u64 xgetbv(u32 index)
	{
	u32 eax, edx;

	asm volatile(".byte 0x0f,0x01,0xd0" /* xgetbv */
	: "=a" (eax), "=d" (edx)
	: "c" (index));
	return eax + ((u64)edx << 32);
	}

	static inline void xsetbv(u32 index, u64 value)
	{
	u32 eax = value;
	u32 edx = value >> 32;

	asm volatile(".byte 0x0f,0x01,0xd1" /* xsetbv */
	: : "a" (eax), "d" (edx), "c" (index));
	}

	#endif /* _ASM_X86_FPU_INTERNAL_H */