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Commit b992c660 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86/fpu: Factor out fpu/signal.c 



fpu/xstate.c has a lot of generic FPU signal frame handling routines,
move them into a separate file: fpu/signal.c.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent c6813144

arch/x86/include/asm/fpu/signal.h

+2 −0
Original line number Diff line number Diff line
@@ -28,4 +28,6 @@ unsigned long 
fpu__alloc_mathframe(unsigned long sp, int ia32_frame,

		     unsigned long *buf_fx, unsigned long *size);



extern void fpu__init_prepare_fx_sw_frame(void);



#endif /* _ASM_X86_FPU_SIGNAL_H */

arch/x86/kernel/fpu/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -2,4 +2,4 @@ 
# Build rules for the FPU support code:

#



obj-y				+= init.o bugs.o core.o xstate.o
 
obj-y				+= init.o bugs.o core.o signal.o xstate.o

arch/x86/kernel/fpu/signal.c

0 → 100644
+404 −0
Original line number Diff line number Diff line 
/*

 * 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 i387_fxsave_struct __user *buf,

				   void __user *fpstate,

				   struct _fpx_sw_bytes *fx_sw)

{

	int min_xstate_size = sizeof(struct i387_fxsave_struct) +

			      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 xsave_struct *xsave = &tsk->thread.fpu.state.xsave;

		struct user_i387_ia32_struct env;

		struct _fpstate_ia32 __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 i387_fsave_struct __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 xsave_struct __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 |= XSTATE_FPSSE;



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



	return err;

}



static inline int copy_fpregs_to_sigframe(struct xsave_struct __user *buf)

{

	int err;



	if (use_xsave())

		err = copy_xregs_to_user(buf);

	else if (use_fxsr())

		err = copy_fxregs_to_user((struct i387_fxsave_struct __user *) buf);

	else

		err = copy_fregs_to_user((struct i387_fsave_struct __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 xsave_struct *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_ia32 __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 xsave_struct *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 = XSTATE_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 & ~XSTATE_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 i387_fxsave_struct);

			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))) {

			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();

			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 i387_fsave_struct);

		size += sizeof(struct i387_fsave_struct);

	}



	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 i387_fsave_struct);

		sp -= sizeof(struct i387_fsave_struct);

	}



	*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 fsave_header_size = sizeof(struct i387_fsave_struct);

	int size = xstate_size + FP_XSTATE_MAGIC2_SIZE;



	if (config_enabled(CONFIG_X86_32))

		size += fsave_header_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)) {

		fx_sw_reserved_ia32 = fx_sw_reserved;

		fx_sw_reserved_ia32.extended_size += fsave_header_size;

	}

}

arch/x86/kernel/fpu/xstate.c

+2 −392
Original line number Diff line number Diff line
@@ -10,7 +10,7 @@ 
#include <asm/fpu/internal.h>

#include <asm/fpu/signal.h>

#include <asm/fpu/regset.h>

#include <asm/sigframe.h>



#include <asm/tlbflush.h>



static const char *xfeature_names[] =
@@ -31,7 +31,6 @@ static const char *xfeature_names[] = 
 */

u64 xfeatures_mask __read_mostly;



static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;

static unsigned int xstate_offsets[XFEATURES_NR_MAX], xstate_sizes[XFEATURES_NR_MAX];

static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8];
@@ -154,395 +153,6 @@ void fpstate_sanitize_xstate(struct fpu *fpu) 
	}

}



/*

 * Check for the presence of extended state information in the

 * user fpstate pointer in the sigcontext.

 */

static inline int check_for_xstate(struct i387_fxsave_struct __user *buf,

				   void __user *fpstate,

				   struct _fpx_sw_bytes *fx_sw)

{

	int min_xstate_size = sizeof(struct i387_fxsave_struct) +

			      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 xsave_struct *xsave = &tsk->thread.fpu.state.xsave;

		struct user_i387_ia32_struct env;

		struct _fpstate_ia32 __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 i387_fsave_struct __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 xsave_struct __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 |= XSTATE_FPSSE;



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



	return err;

}



static inline int copy_fpregs_to_sigframe(struct xsave_struct __user *buf)

{

	int err;



	if (use_xsave())

		err = copy_xregs_to_user(buf);

	else if (use_fxsr())

		err = copy_fxregs_to_user((struct i387_fxsave_struct __user *) buf);

	else

		err = copy_fregs_to_user((struct i387_fsave_struct __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 xsave_struct *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_ia32 __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 xsave_struct *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 = XSTATE_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 & ~XSTATE_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 i387_fxsave_struct);

			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))) {

			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();

			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 i387_fsave_struct);

		size += sizeof(struct i387_fsave_struct);

	}



	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 i387_fsave_struct);

		sp -= sizeof(struct i387_fsave_struct);

	}



	*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.

 */

static void prepare_fx_sw_frame(void)

{

	int fsave_header_size = sizeof(struct i387_fsave_struct);

	int size = xstate_size + FP_XSTATE_MAGIC2_SIZE;



	if (config_enabled(CONFIG_X86_32))

		size += fsave_header_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)) {

		fx_sw_reserved_ia32 = fx_sw_reserved;

		fx_sw_reserved_ia32.extended_size += fsave_header_size;

	}

}



/*

 * Enable the extended processor state save/restore feature.

 * Called once per CPU onlining.
@@ -741,7 +351,7 @@ void fpu__init_system_xstate(void) 
	init_xstate_size();



	update_regset_xstate_info(xstate_size, xfeatures_mask);

	prepare_fx_sw_frame();

	fpu__init_prepare_fx_sw_frame();

	setup_init_fpu_buf();



	pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is 0x%x bytes, using '%s' format.\n",