arch/x86/kernel/fpu/signal.c - codeaurora/cp-linux - Gitiles

 /*
  * FPU signal frame handling routines.
  */

 #include <linux/compat.h>
 #include <linux/cpu.h>

 #include <asm/fpu/internal.h>
 #include <asm/fpu/signal.h>
 #include <asm/fpu/regset.h>

 #include <asm/sigframe.h>

 static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;

 /*
  * Check for the presence of extended state information in the
  * user fpstate pointer in the sigcontext.
  */
 static inline int check_for_xstate(struct fxregs_state __user *buf,
 				   void __user *fpstate,
 				   struct _fpx_sw_bytes *fx_sw)
 {
 	int min_xstate_size = sizeof(struct fxregs_state) +
 			      sizeof(struct xstate_header);
 	unsigned int magic2;

 	if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
 		return -1;

 	/* Check for the first magic field and other error scenarios. */
 	if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
 	    fx_sw->xstate_size < min_xstate_size ||
 	    fx_sw->xstate_size > xstate_size ||
 	    fx_sw->xstate_size > fx_sw->extended_size)
 		return -1;

 	/*
 	 * Check for the presence of second magic word at the end of memory
 	 * layout. This detects the case where the user just copied the legacy
 	 * fpstate layout with out copying the extended state information
 	 * in the memory layout.
 	 */
 	if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
 	    || magic2 != FP_XSTATE_MAGIC2)
 		return -1;

 	return 0;
 }

 /*
  * Signal frame handlers.
  */
 static inline int save_fsave_header(struct task_struct *tsk, void __user *buf)
 {
 	if (use_fxsr()) {
 		struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
 		struct user_i387_ia32_struct env;
 		struct _fpstate_32 __user *fp = buf;

 		convert_from_fxsr(&env, tsk);

 		if (__copy_to_user(buf, &env, sizeof(env)) ||
 		    __put_user(xsave->i387.swd, &fp->status) ||
 		    __put_user(X86_FXSR_MAGIC, &fp->magic))
 			return -1;
 	} else {
 		struct fregs_state __user *fp = buf;
 		u32 swd;
 		if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
 			return -1;
 	}

 	return 0;
 }

 static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
 {
 	struct xregs_state __user *x = buf;
 	struct _fpx_sw_bytes *sw_bytes;
 	u32 xfeatures;
 	int err;

 	/* Setup the bytes not touched by the [f]xsave and reserved for SW. */
 	sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved;
 	err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes));

 	if (!use_xsave())
 		return err;

 	err |= __put_user(FP_XSTATE_MAGIC2, (__u32 *)(buf + xstate_size));

 	/*
 	 * Read the xfeatures which we copied (directly from the cpu or
 	 * from the state in task struct) to the user buffers.
 	 */
 	err |= __get_user(xfeatures, (__u32 *)&x->header.xfeatures);

 	/*
 	 * For legacy compatible, we always set FP/SSE bits in the bit
 	 * vector while saving the state to the user context. This will
 	 * enable us capturing any changes(during sigreturn) to
 	 * the FP/SSE bits by the legacy applications which don't touch
 	 * xfeatures in the xsave header.
 	 *
 	 * xsave aware apps can change the xfeatures in the xsave
 	 * header as well as change any contents in the memory layout.
 	 * xrestore as part of sigreturn will capture all the changes.
 	 */
 	xfeatures |= XFEATURE_MASK_FPSSE;

 	err |= __put_user(xfeatures, (__u32 *)&x->header.xfeatures);

 	return err;
 }

 static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
 {
 	int err;

 	if (use_xsave())
 		err = copy_xregs_to_user(buf);
 	else if (use_fxsr())
 		err = copy_fxregs_to_user((struct fxregs_state __user *) buf);
 	else
 		err = copy_fregs_to_user((struct fregs_state __user *) buf);

 	if (unlikely(err) && __clear_user(buf, xstate_size))
 		err = -EFAULT;
 	return err;
 }

 /*
  * Save the fpu, extended register state to the user signal frame.
  *
  * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
  *  state is copied.
  *  'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
  *
  *	buf == buf_fx for 64-bit frames and 32-bit fsave frame.
  *	buf != buf_fx for 32-bit frames with fxstate.
  *
  * If the fpu, extended register state is live, save the state directly
  * to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
  * copy the thread's fpu state to the user frame starting at 'buf_fx'.
  *
  * If this is a 32-bit frame with fxstate, put a fsave header before
  * the aligned state at 'buf_fx'.
  *
  * For [f]xsave state, update the SW reserved fields in the [f]xsave frame
  * indicating the absence/presence of the extended state to the user.
  */
 int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
 {
 	struct xregs_state *xsave = &current->thread.fpu.state.xsave;
 	struct task_struct *tsk = current;
 	int ia32_fxstate = (buf != buf_fx);

 	ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
 			 config_enabled(CONFIG_IA32_EMULATION));

 	if (!access_ok(VERIFY_WRITE, buf, size))
 		return -EACCES;

 	if (!static_cpu_has(X86_FEATURE_FPU))
 		return fpregs_soft_get(current, NULL, 0,
 			sizeof(struct user_i387_ia32_struct), NULL,
 			(struct _fpstate_32 __user *) buf) ? -1 : 1;

 	if (fpregs_active()) {
 		/* Save the live register state to the user directly. */
 		if (copy_fpregs_to_sigframe(buf_fx))
 			return -1;
 		/* Update the thread's fxstate to save the fsave header. */
 		if (ia32_fxstate)
 			copy_fxregs_to_kernel(&tsk->thread.fpu);
 	} else {
 		fpstate_sanitize_xstate(&tsk->thread.fpu);
 		if (__copy_to_user(buf_fx, xsave, xstate_size))
 			return -1;
 	}

 	/* Save the fsave header for the 32-bit frames. */
 	if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
 		return -1;

 	if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
 		return -1;

 	return 0;
 }

 static inline void
 sanitize_restored_xstate(struct task_struct *tsk,
 			 struct user_i387_ia32_struct *ia32_env,
 			 u64 xfeatures, int fx_only)
 {
 	struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
 	struct xstate_header *header = &xsave->header;

 	if (use_xsave()) {
 		/* These bits must be zero. */
 		memset(header->reserved, 0, 48);

 		/*
 		 * Init the state that is not present in the memory
 		 * layout and not enabled by the OS.
 		 */
 		if (fx_only)
 			header->xfeatures = XFEATURE_MASK_FPSSE;
 		else
 			header->xfeatures &= (xfeatures_mask & xfeatures);
 	}

 	if (use_fxsr()) {
 		/*
 		 * mscsr reserved bits must be masked to zero for security
 		 * reasons.
 		 */
 		xsave->i387.mxcsr &= mxcsr_feature_mask;

 		convert_to_fxsr(tsk, ia32_env);
 	}
 }

 /*
  * Restore the extended state if present. Otherwise, restore the FP/SSE state.
  */
 static inline int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
 {
 	if (use_xsave()) {
 		if ((unsigned long)buf % 64 || fx_only) {
 			u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
 			copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
 			return copy_user_to_fxregs(buf);
 		} else {
 			u64 init_bv = xfeatures_mask & ~xbv;
 			if (unlikely(init_bv))
 				copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
 			return copy_user_to_xregs(buf, xbv);
 		}
 	} else if (use_fxsr()) {
 		return copy_user_to_fxregs(buf);
 	} else
 		return copy_user_to_fregs(buf);
 }

 static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 {
 	int ia32_fxstate = (buf != buf_fx);
 	struct task_struct *tsk = current;
 	struct fpu *fpu = &tsk->thread.fpu;
 	int state_size = xstate_size;
 	u64 xfeatures = 0;
 	int fx_only = 0;

 	ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
 			 config_enabled(CONFIG_IA32_EMULATION));

 	if (!buf) {
 		fpu__clear(fpu);
 		return 0;
 	}

 	if (!access_ok(VERIFY_READ, buf, size))
 		return -EACCES;

 	fpu__activate_curr(fpu);

 	if (!static_cpu_has(X86_FEATURE_FPU))
 		return fpregs_soft_set(current, NULL,
 				       0, sizeof(struct user_i387_ia32_struct),
 				       NULL, buf) != 0;

 	if (use_xsave()) {
 		struct _fpx_sw_bytes fx_sw_user;
 		if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
 			/*
 			 * Couldn't find the extended state information in the
 			 * memory layout. Restore just the FP/SSE and init all
 			 * the other extended state.
 			 */
 			state_size = sizeof(struct fxregs_state);
 			fx_only = 1;
 		} else {
 			state_size = fx_sw_user.xstate_size;
 			xfeatures = fx_sw_user.xfeatures;
 		}
 	}

 	if (ia32_fxstate) {
 		/*
 		 * For 32-bit frames with fxstate, copy the user state to the
 		 * thread's fpu state, reconstruct fxstate from the fsave
 		 * header. Sanitize the copied state etc.
 		 */
 		struct fpu *fpu = &tsk->thread.fpu;
 		struct user_i387_ia32_struct env;
 		int err = 0;

 		/*
 		 * Drop the current fpu which clears fpu->fpstate_active. This ensures
 		 * that any context-switch during the copy of the new state,
 		 * avoids the intermediate state from getting restored/saved.
 		 * Thus avoiding the new restored state from getting corrupted.
 		 * We will be ready to restore/save the state only after
 		 * fpu->fpstate_active is again set.
 		 */
 		fpu__drop(fpu);

 		if (__copy_from_user(&fpu->state.xsave, buf_fx, state_size) ||
 		    __copy_from_user(&env, buf, sizeof(env)) ||
 		    (state_size > offsetof(struct xregs_state, header) &&
 		     fpu->state.xsave.header.xcomp_bv)) {
 			fpstate_init(&fpu->state);
 			err = -1;
 		} else {
 			sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
 		}

 		fpu->fpstate_active = 1;
 		if (use_eager_fpu()) {
 			preempt_disable();
 			fpu__restore(fpu);
 			preempt_enable();
 		}

 		return err;
 	} else {
 		/*
 		 * For 64-bit frames and 32-bit fsave frames, restore the user
 		 * state to the registers directly (with exceptions handled).
 		 */
 		user_fpu_begin();
 		if (copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) {
 			fpu__clear(fpu);
 			return -1;
 		}
 	}

 	return 0;
 }

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

 /*
  * Restore FPU state from a sigframe:
  */
 int fpu__restore_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 fregs_state);
 		size += sizeof(struct fregs_state);
 	}

 	return __fpu__restore_sig(buf, buf_fx, size);
 }

 unsigned long
 fpu__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 fregs_state);
 		sp -= sizeof(struct fregs_state);
 	}

 	*size = frame_size;

 	return sp;
 }
 /*
  * Prepare the SW reserved portion of the fxsave memory layout, indicating
  * the presence of the extended state information in the memory layout
  * pointed by the fpstate pointer in the sigcontext.
  * This will be saved when ever the FP and extended state context is
  * saved on the user stack during the signal handler delivery to the user.
  */
 void fpu__init_prepare_fx_sw_frame(void)
 {
 	int size = xstate_size + FP_XSTATE_MAGIC2_SIZE;

 	fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
 	fx_sw_reserved.extended_size = size;
 	fx_sw_reserved.xfeatures = xfeatures_mask;
 	fx_sw_reserved.xstate_size = xstate_size;

 	if (config_enabled(CONFIG_IA32_EMULATION) ||
 	    config_enabled(CONFIG_X86_32)) {
 		int fsave_header_size = sizeof(struct fregs_state);

 		fx_sw_reserved_ia32 = fx_sw_reserved;
 		fx_sw_reserved_ia32.extended_size = size + fsave_header_size;
 	}
 }
	/*
	* FPU signal frame handling routines.
	*/

	#include <linux/compat.h>
	#include <linux/cpu.h>

	#include <asm/fpu/internal.h>
	#include <asm/fpu/signal.h>
	#include <asm/fpu/regset.h>

	#include <asm/sigframe.h>

	static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;

	/*
	* Check for the presence of extended state information in the
	* user fpstate pointer in the sigcontext.
	*/
	static inline int check_for_xstate(struct fxregs_state __user *buf,
	void __user *fpstate,
	struct _fpx_sw_bytes *fx_sw)
	{
	int min_xstate_size = sizeof(struct fxregs_state) +
	sizeof(struct xstate_header);
	unsigned int magic2;

	if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
	return -1;

	/* Check for the first magic field and other error scenarios. */
	if (fx_sw->magic1 != FP_XSTATE_MAGIC1 \|\|
	fx_sw->xstate_size < min_xstate_size \|\|
	fx_sw->xstate_size > xstate_size \|\|
	fx_sw->xstate_size > fx_sw->extended_size)
	return -1;

	/*
	* Check for the presence of second magic word at the end of memory
	* layout. This detects the case where the user just copied the legacy
	* fpstate layout with out copying the extended state information
	* in the memory layout.
	*/
	if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
	\|\| magic2 != FP_XSTATE_MAGIC2)
	return -1;

	return 0;
	}

	/*
	* Signal frame handlers.
	*/
	static inline int save_fsave_header(struct task_struct tsk, void __user buf)
	{
	if (use_fxsr()) {
	struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
	struct user_i387_ia32_struct env;
	struct _fpstate_32 __user *fp = buf;

	convert_from_fxsr(&env, tsk);

	if (__copy_to_user(buf, &env, sizeof(env)) \|\|
	__put_user(xsave->i387.swd, &fp->status) \|\|
	__put_user(X86_FXSR_MAGIC, &fp->magic))
	return -1;
	} else {
	struct fregs_state __user *fp = buf;
	u32 swd;
	if (__get_user(swd, &fp->swd) \|\| __put_user(swd, &fp->status))
	return -1;
	}

	return 0;
	}

	static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
	{
	struct xregs_state __user *x = buf;
	struct _fpx_sw_bytes *sw_bytes;
	u32 xfeatures;
	int err;

	/* Setup the bytes not touched by the [f]xsave and reserved for SW. */
	sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved;
	err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes));

	if (!use_xsave())
	return err;

	err \|= __put_user(FP_XSTATE_MAGIC2, (__u32 *)(buf + xstate_size));

	/*
	* Read the xfeatures which we copied (directly from the cpu or
	* from the state in task struct) to the user buffers.
	*/
	err \|= __get_user(xfeatures, (__u32 *)&x->header.xfeatures);

	/*
	* For legacy compatible, we always set FP/SSE bits in the bit
	* vector while saving the state to the user context. This will
	* enable us capturing any changes(during sigreturn) to
	* the FP/SSE bits by the legacy applications which don't touch
	* xfeatures in the xsave header.
	*
	* xsave aware apps can change the xfeatures in the xsave
	* header as well as change any contents in the memory layout.
	* xrestore as part of sigreturn will capture all the changes.
	*/
	xfeatures \|= XFEATURE_MASK_FPSSE;

	err \|= __put_user(xfeatures, (__u32 *)&x->header.xfeatures);

	return err;
	}

	static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
	{
	int err;

	if (use_xsave())
	err = copy_xregs_to_user(buf);
	else if (use_fxsr())
	err = copy_fxregs_to_user((struct fxregs_state __user *) buf);
	else
	err = copy_fregs_to_user((struct fregs_state __user *) buf);

	if (unlikely(err) && __clear_user(buf, xstate_size))
	err = -EFAULT;
	return err;
	}

	/*
	* Save the fpu, extended register state to the user signal frame.
	*
	* 'buf_fx' is the 64-byte aligned pointer at which the [f\|fx\|x]save
	* state is copied.
	* 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
	*
	* buf == buf_fx for 64-bit frames and 32-bit fsave frame.
	* buf != buf_fx for 32-bit frames with fxstate.
	*
	* If the fpu, extended register state is live, save the state directly
	* to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
	* copy the thread's fpu state to the user frame starting at 'buf_fx'.
	*
	* If this is a 32-bit frame with fxstate, put a fsave header before
	* the aligned state at 'buf_fx'.
	*
	* For [f]xsave state, update the SW reserved fields in the [f]xsave frame
	* indicating the absence/presence of the extended state to the user.
	*/
	int copy_fpstate_to_sigframe(void __user buf, void __user buf_fx, int size)
	{
	struct xregs_state *xsave = &current->thread.fpu.state.xsave;
	struct task_struct *tsk = current;
	int ia32_fxstate = (buf != buf_fx);

	ia32_fxstate &= (config_enabled(CONFIG_X86_32) \|\|
	config_enabled(CONFIG_IA32_EMULATION));

	if (!access_ok(VERIFY_WRITE, buf, size))
	return -EACCES;

	if (!static_cpu_has(X86_FEATURE_FPU))
	return fpregs_soft_get(current, NULL, 0,
	sizeof(struct user_i387_ia32_struct), NULL,
	(struct _fpstate_32 __user *) buf) ? -1 : 1;

	if (fpregs_active()) {
	/* Save the live register state to the user directly. */
	if (copy_fpregs_to_sigframe(buf_fx))
	return -1;
	/* Update the thread's fxstate to save the fsave header. */
	if (ia32_fxstate)
	copy_fxregs_to_kernel(&tsk->thread.fpu);
	} else {
	fpstate_sanitize_xstate(&tsk->thread.fpu);
	if (__copy_to_user(buf_fx, xsave, xstate_size))
	return -1;
	}

	/* Save the fsave header for the 32-bit frames. */
	if ((ia32_fxstate \|\| !use_fxsr()) && save_fsave_header(tsk, buf))
	return -1;

	if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
	return -1;

	return 0;
	}

	static inline void
	sanitize_restored_xstate(struct task_struct *tsk,
	struct user_i387_ia32_struct *ia32_env,
	u64 xfeatures, int fx_only)
	{
	struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
	struct xstate_header *header = &xsave->header;

	if (use_xsave()) {
	/* These bits must be zero. */
	memset(header->reserved, 0, 48);

	/*
	* Init the state that is not present in the memory
	* layout and not enabled by the OS.
	*/
	if (fx_only)
	header->xfeatures = XFEATURE_MASK_FPSSE;
	else
	header->xfeatures &= (xfeatures_mask & xfeatures);
	}

	if (use_fxsr()) {
	/*
	* mscsr reserved bits must be masked to zero for security
	* reasons.
	*/
	xsave->i387.mxcsr &= mxcsr_feature_mask;

	convert_to_fxsr(tsk, ia32_env);
	}
	}

	/*
	* Restore the extended state if present. Otherwise, restore the FP/SSE state.
	*/
	static inline int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
	{
	if (use_xsave()) {
	if ((unsigned long)buf % 64 \|\| fx_only) {
	u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
	copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
	return copy_user_to_fxregs(buf);
	} else {
	u64 init_bv = xfeatures_mask & ~xbv;
	if (unlikely(init_bv))
	copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
	return copy_user_to_xregs(buf, xbv);
	}
	} else if (use_fxsr()) {
	return copy_user_to_fxregs(buf);
	} else
	return copy_user_to_fregs(buf);
	}

	static int __fpu__restore_sig(void __user buf, void __user buf_fx, int size)
	{
	int ia32_fxstate = (buf != buf_fx);
	struct task_struct *tsk = current;
	struct fpu *fpu = &tsk->thread.fpu;
	int state_size = xstate_size;
	u64 xfeatures = 0;
	int fx_only = 0;

	ia32_fxstate &= (config_enabled(CONFIG_X86_32) \|\|
	config_enabled(CONFIG_IA32_EMULATION));

	if (!buf) {
	fpu__clear(fpu);
	return 0;
	}

	if (!access_ok(VERIFY_READ, buf, size))
	return -EACCES;

	fpu__activate_curr(fpu);

	if (!static_cpu_has(X86_FEATURE_FPU))
	return fpregs_soft_set(current, NULL,
	0, sizeof(struct user_i387_ia32_struct),
	NULL, buf) != 0;

	if (use_xsave()) {
	struct _fpx_sw_bytes fx_sw_user;
	if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
	/*
	* Couldn't find the extended state information in the
	* memory layout. Restore just the FP/SSE and init all
	* the other extended state.
	*/
	state_size = sizeof(struct fxregs_state);
	fx_only = 1;
	} else {
	state_size = fx_sw_user.xstate_size;
	xfeatures = fx_sw_user.xfeatures;
	}
	}

	if (ia32_fxstate) {
	/*
	* For 32-bit frames with fxstate, copy the user state to the
	* thread's fpu state, reconstruct fxstate from the fsave
	* header. Sanitize the copied state etc.
	*/
	struct fpu *fpu = &tsk->thread.fpu;
	struct user_i387_ia32_struct env;
	int err = 0;

	/*
	* Drop the current fpu which clears fpu->fpstate_active. This ensures
	* that any context-switch during the copy of the new state,
	* avoids the intermediate state from getting restored/saved.
	* Thus avoiding the new restored state from getting corrupted.
	* We will be ready to restore/save the state only after
	* fpu->fpstate_active is again set.
	*/
	fpu__drop(fpu);

	if (__copy_from_user(&fpu->state.xsave, buf_fx, state_size) \|\|
	__copy_from_user(&env, buf, sizeof(env)) \|\|
	(state_size > offsetof(struct xregs_state, header) &&
	fpu->state.xsave.header.xcomp_bv)) {
	fpstate_init(&fpu->state);
	err = -1;
	} else {
	sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
	}

	fpu->fpstate_active = 1;
	if (use_eager_fpu()) {
	preempt_disable();
	fpu__restore(fpu);
	preempt_enable();
	}

	return err;
	} else {
	/*
	* For 64-bit frames and 32-bit fsave frames, restore the user
	* state to the registers directly (with exceptions handled).
	*/
	user_fpu_begin();
	if (copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) {
	fpu__clear(fpu);
	return -1;
	}
	}

	return 0;
	}

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

	/*
	* Restore FPU state from a sigframe:
	*/
	int fpu__restore_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 fregs_state);
	size += sizeof(struct fregs_state);
	}

	return __fpu__restore_sig(buf, buf_fx, size);
	}

	unsigned long
	fpu__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 fregs_state);
	sp -= sizeof(struct fregs_state);
	}

	*size = frame_size;

	return sp;
	}
	/*
	* Prepare the SW reserved portion of the fxsave memory layout, indicating
	* the presence of the extended state information in the memory layout
	* pointed by the fpstate pointer in the sigcontext.
	* This will be saved when ever the FP and extended state context is
	* saved on the user stack during the signal handler delivery to the user.
	*/
	void fpu__init_prepare_fx_sw_frame(void)
	{
	int size = xstate_size + FP_XSTATE_MAGIC2_SIZE;

	fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
	fx_sw_reserved.extended_size = size;
	fx_sw_reserved.xfeatures = xfeatures_mask;
	fx_sw_reserved.xstate_size = xstate_size;

	if (config_enabled(CONFIG_IA32_EMULATION) \|\|
	config_enabled(CONFIG_X86_32)) {
	int fsave_header_size = sizeof(struct fregs_state);

	fx_sw_reserved_ia32 = fx_sw_reserved;
	fx_sw_reserved_ia32.extended_size = size + fsave_header_size;
	}
	}