[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / xsave.c

/*
 * xsave/xrstor support.
 *
 * Author: Suresh Siddha <suresh.b.siddha@intel.com>
 */
#include <linux/bootmem.h>
#include <linux/compat.h>
#include <asm/i387.h>
#include <asm/fpu-internal.h>
#ifdef CONFIG_IA32_EMULATION
#include <asm/sigcontext32.h>
#endif
#include <asm/xcr.h>

/*
 * Supported feature mask by the CPU and the kernel.
 */
u64 pcntxt_mask;

/*
 * Represents init state for the supported extended state.
 */
static struct xsave_struct *init_xstate_buf;

struct _fpx_sw_bytes fx_sw_reserved;
#ifdef CONFIG_IA32_EMULATION
struct _fpx_sw_bytes fx_sw_reserved_ia32;
#endif

static unsigned int *xstate_offsets, *xstate_sizes, xstate_features;

/*
 * If a processor implementation discern that a processor state component is
 * in its initialized state it may modify the corresponding bit in the
 * xsave_hdr.xstate_bv as '0', with out modifying the corresponding memory
 * layout in the case of xsaveopt. While presenting the xstate information to
 * the user, we always ensure that the memory layout of a feature will be in
 * the init state if the corresponding header bit is zero. This is to ensure
 * that the user doesn't see some stale state in the memory layout during
 * signal handling, debugging etc.
 */
void __sanitize_i387_state(struct task_struct *tsk)
{
	u64 xstate_bv;
	int feature_bit = 0x2;
	struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave;

	if (!fx)
		return;

	BUG_ON(__thread_has_fpu(tsk));

	xstate_bv = tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv;

	/*
	 * None of the feature bits are in init state. So nothing else
	 * to do for us, as the memory layout is up to date.
	 */
	if ((xstate_bv & pcntxt_mask) == pcntxt_mask)
		return;

	/*
	 * FP is in init state
	 */
	if (!(xstate_bv & XSTATE_FP)) {
		fx->cwd = 0x37f;
		fx->swd = 0;
		fx->twd = 0;
		fx->fop = 0;
		fx->rip = 0;
		fx->rdp = 0;
		memset(&fx->st_space[0], 0, 128);
	}

	/*
	 * SSE is in init state
	 */
	if (!(xstate_bv & XSTATE_SSE))
		memset(&fx->xmm_space[0], 0, 256);

	xstate_bv = (pcntxt_mask & ~xstate_bv) >> 2;

	/*
	 * Update all the other memory layouts for which the corresponding
	 * header bit is in the init state.
	 */
	while (xstate_bv) {
		if (xstate_bv & 0x1) {
			int offset = xstate_offsets[feature_bit];
			int size = xstate_sizes[feature_bit];

			memcpy(((void *) fx) + offset,
			       ((void *) init_xstate_buf) + offset,
			       size);
		}

		xstate_bv >>= 1;
		feature_bit++;
	}
}

/*
 * Check for the presence of extended state information in the
 * user fpstate pointer in the sigcontext.
 */
int check_for_xstate(struct i387_fxsave_struct __user *buf,
		     void __user *fpstate,
		     struct _fpx_sw_bytes *fx_sw_user)
{
	int min_xstate_size = sizeof(struct i387_fxsave_struct) +
			      sizeof(struct xsave_hdr_struct);
	unsigned int magic2;
	int err;

	err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0],
			       sizeof(struct _fpx_sw_bytes));
	if (err)
		return -EFAULT;

	/*
	 * First Magic check failed.
	 */
	if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1)
		return -EINVAL;

	/*
	 * Check for error scenarios.
	 */
	if (fx_sw_user->xstate_size < min_xstate_size ||
	    fx_sw_user->xstate_size > xstate_size ||
	    fx_sw_user->xstate_size > fx_sw_user->extended_size)
		return -EINVAL;

	err = __get_user(magic2, (__u32 *) (((void *)fpstate) +
					    fx_sw_user->extended_size -
					    FP_XSTATE_MAGIC2_SIZE));
	if (err)
		return err;
	/*
	 * 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 (magic2 != FP_XSTATE_MAGIC2)
		return -EFAULT;

	return 0;
}

#ifdef CONFIG_X86_64
/*
 * Signal frame handlers.
 */

int save_i387_xstate(void __user *buf)
{
	struct task_struct *tsk = current;
	int err = 0;

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

	BUG_ON(sig_xstate_size < xstate_size);

	if ((unsigned long)buf % 64)
		printk("save_i387_xstate: bad fpstate %p\n", buf);

	if (!used_math())
		return 0;

	if (user_has_fpu()) {
		if (use_xsave())
			err = xsave_user(buf);
		else
			err = fxsave_user(buf);

		if (err)
			return err;
		user_fpu_end();
	} else {
		sanitize_i387_state(tsk);
		if (__copy_to_user(buf, &tsk->thread.fpu.state->fxsave,
				   xstate_size))
			return -1;
	}

	clear_used_math(); /* trigger finit */

	if (use_xsave()) {
		struct _fpstate __user *fx = buf;
		struct _xstate __user *x = buf;
		u64 xstate_bv;

		err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved,
				     sizeof(struct _fpx_sw_bytes));

		err |= __put_user(FP_XSTATE_MAGIC2,
				  (__u32 __user *) (buf + sig_xstate_size
						    - FP_XSTATE_MAGIC2_SIZE));

		/*
		 * Read the xstate_bv which we copied (directly from the cpu or
		 * from the state in task struct) to the user buffers and
		 * set the FP/SSE bits.
		 */
		err |= __get_user(xstate_bv, &x->xstate_hdr.xstate_bv);

		/*
		 * 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
		 * xstate_bv in the xsave header.
		 *
		 * xsave aware apps can change the xstate_bv in the xsave
		 * header as well as change any contents in the memory layout.
		 * xrestore as part of sigreturn will capture all the changes.
		 */
		xstate_bv |= XSTATE_FPSSE;

		err |= __put_user(xstate_bv, &x->xstate_hdr.xstate_bv);

		if (err)
			return err;
	}

	return 1;
}

/*
 * Restore the extended state if present. Otherwise, restore the FP/SSE
 * state.
 */
static int restore_user_xstate(void __user *buf)
{
	struct _fpx_sw_bytes fx_sw_user;
	u64 mask;
	int err;

	if (((unsigned long)buf % 64) ||
	     check_for_xstate(buf, buf, &fx_sw_user))
		goto fx_only;

	mask = fx_sw_user.xstate_bv;

	/*
	 * restore the state passed by the user.
	 */
	err = xrestore_user(buf, mask);
	if (err)
		return err;

	/*
	 * init the state skipped by the user.
	 */
	mask = pcntxt_mask & ~mask;
	if (unlikely(mask))
		xrstor_state(init_xstate_buf, mask);

	return 0;

fx_only:
	/*
	 * couldn't find the extended state information in the
	 * memory layout. Restore just the FP/SSE and init all
	 * the other extended state.
	 */
	xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE);
	return fxrstor_checking((__force struct i387_fxsave_struct *)buf);
}

/*
 * This restores directly out of user space. Exceptions are handled.
 */
int restore_i387_xstate(void __user *buf)
{
	struct task_struct *tsk = current;
	int err = 0;

	if (!buf) {
		if (used_math())
			goto clear;
		return 0;
	} else
		if (!access_ok(VERIFY_READ, buf, sig_xstate_size))
			return -EACCES;

	if (!used_math()) {
		err = init_fpu(tsk);
		if (err)
			return err;
	}

	user_fpu_begin();
	if (use_xsave())
		err = restore_user_xstate(buf);
	else
		err = fxrstor_checking((__force struct i387_fxsave_struct *)
				       buf);
	if (unlikely(err)) {
		/*
		 * Encountered an error while doing the restore from the
		 * user buffer, clear the fpu state.
		 */
clear:
		clear_fpu(tsk);
		clear_used_math();
	}
	return err;
}
#endif

/*
 * 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 size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) +
			     FP_XSTATE_MAGIC2_SIZE;

	sig_xstate_size = sizeof(struct _fpstate) + size_extended;

#ifdef CONFIG_IA32_EMULATION
	sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended;
#endif

	memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved));

	fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
	fx_sw_reserved.extended_size = sig_xstate_size;
	fx_sw_reserved.xstate_bv = pcntxt_mask;
	fx_sw_reserved.xstate_size = xstate_size;
#ifdef CONFIG_IA32_EMULATION
	memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved,
	       sizeof(struct _fpx_sw_bytes));
	fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size;
#endif
}

#ifdef CONFIG_X86_64
unsigned int sig_xstate_size = sizeof(struct _fpstate);
#endif

/*
 * Enable the extended processor state save/restore feature
 */
static inline void xstate_enable(void)
{
	set_in_cr4(X86_CR4_OSXSAVE);
	xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask);
}

/*
 * Record the offsets and sizes of different state managed by the xsave
 * memory layout.
 */
static void __init setup_xstate_features(void)
{
	int eax, ebx, ecx, edx, leaf = 0x2;

	xstate_features = fls64(pcntxt_mask);
	xstate_offsets = alloc_bootmem(xstate_features * sizeof(int));
	xstate_sizes = alloc_bootmem(xstate_features * sizeof(int));

	do {
		cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx);

		if (eax == 0)
			break;

		xstate_offsets[leaf] = ebx;
		xstate_sizes[leaf] = eax;

		leaf++;
	} while (1);
}

/*
 * setup the xstate image representing the init state
 */
static void __init setup_xstate_init(void)
{
	setup_xstate_features();

	/*
	 * Setup init_xstate_buf to represent the init state of
	 * all the features managed by the xsave
	 */
	init_xstate_buf = alloc_bootmem_align(xstate_size,
					      __alignof__(struct xsave_struct));
	init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;

	clts();
	/*
	 * Init all the features state with header_bv being 0x0
	 */
	xrstor_state(init_xstate_buf, -1);
	/*
	 * Dump the init state again. This is to identify the init state
	 * of any feature which is not represented by all zero's.
	 */
	xsave_state(init_xstate_buf, -1);
	stts();
}

/*
 * Enable and initialize the xsave feature.
 */
static void __init xstate_enable_boot_cpu(void)
{
	unsigned int eax, ebx, ecx, edx;

	if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
		WARN(1, KERN_ERR "XSTATE_CPUID missing\n");
		return;
	}

	cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
	pcntxt_mask = eax + ((u64)edx << 32);

	if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) {
		printk(KERN_ERR "FP/SSE not shown under xsave features 0x%llx\n",
		       pcntxt_mask);
		BUG();
	}

	/*
	 * Support only the state known to OS.
	 */
	pcntxt_mask = pcntxt_mask & XCNTXT_MASK;

	xstate_enable();

	/*
	 * Recompute the context size for enabled features
	 */
	cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
	xstate_size = ebx;

	update_regset_xstate_info(xstate_size, pcntxt_mask);
	prepare_fx_sw_frame();

	setup_xstate_init();

	printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%llx, "
	       "cntxt size 0x%x\n",
	       pcntxt_mask, xstate_size);
}

/*
 * For the very first instance, this calls xstate_enable_boot_cpu();
 * for all subsequent instances, this calls xstate_enable().
 *
 * This is somewhat obfuscated due to the lack of powerful enough
 * overrides for the section checks.
 */
void __cpuinit xsave_init(void)
{
	static __refdata void (*next_func)(void) = xstate_enable_boot_cpu;
	void (*this_func)(void);

	if (!cpu_has_xsave)
		return;

	this_func = next_func;
	next_func = xstate_enable;
	this_func();
}
Commit	Line	Data
dc1e35c6 SS	1	/*
	2	* xsave/xrstor support.
	3	*
	4	* Author: Suresh Siddha <suresh.b.siddha@intel.com>
	5	*/
	6	#include <linux/bootmem.h>
	7	#include <linux/compat.h>
	8	#include <asm/i387.h>
1361b83a	9	#include <asm/fpu-internal.h>
c37b5efe SS	10	#ifdef CONFIG_IA32_EMULATION
	11	#include <asm/sigcontext32.h>
	12	#endif
6152e4b1	13	#include <asm/xcr.h>
dc1e35c6 SS	14
	15	/*
	16	* Supported feature mask by the CPU and the kernel.
	17	*/
6152e4b1	18	u64 pcntxt_mask;
dc1e35c6	19
45c2d7f4 RR	20	/*
	21	* Represents init state for the supported extended state.
	22	*/
	23	static struct xsave_struct *init_xstate_buf;
	24
c37b5efe SS	25	struct _fpx_sw_bytes fx_sw_reserved;
	26	#ifdef CONFIG_IA32_EMULATION
	27	struct _fpx_sw_bytes fx_sw_reserved_ia32;
	28	#endif
	29
a1488f8b SS	30	static unsigned int xstate_offsets, xstate_sizes, xstate_features;
a1488f8b SS	31
29104e10 SS	32	/*
	33	* If a processor implementation discern that a processor state component is
	34	* in its initialized state it may modify the corresponding bit in the
	35	* xsave_hdr.xstate_bv as '0', with out modifying the corresponding memory
	36	* layout in the case of xsaveopt. While presenting the xstate information to
	37	* the user, we always ensure that the memory layout of a feature will be in
	38	* the init state if the corresponding header bit is zero. This is to ensure
	39	* that the user doesn't see some stale state in the memory layout during
	40	* signal handling, debugging etc.
	41	*/
	42	void __sanitize_i387_state(struct task_struct *tsk)
	43	{
	44	u64 xstate_bv;
	45	int feature_bit = 0x2;
	46	struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave;
	47
	48	if (!fx)
	49	return;
	50
f94edacf	51	BUG_ON(__thread_has_fpu(tsk));
29104e10 SS	52
	53	xstate_bv = tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv;
	54
	55	/*
	56	* None of the feature bits are in init state. So nothing else
0d2eb44f	57	* to do for us, as the memory layout is up to date.
29104e10 SS	58	*/
	59	if ((xstate_bv & pcntxt_mask) == pcntxt_mask)
	60	return;
	61
	62	/*
	63	* FP is in init state
	64	*/
	65	if (!(xstate_bv & XSTATE_FP)) {
	66	fx->cwd = 0x37f;
	67	fx->swd = 0;
	68	fx->twd = 0;
	69	fx->fop = 0;
	70	fx->rip = 0;
	71	fx->rdp = 0;
	72	memset(&fx->st_space[0], 0, 128);
	73	}
	74
	75	/*
	76	* SSE is in init state
	77	*/
	78	if (!(xstate_bv & XSTATE_SSE))
	79	memset(&fx->xmm_space[0], 0, 256);
	80
	81	xstate_bv = (pcntxt_mask & ~xstate_bv) >> 2;
	82
	83	/*
	84	* Update all the other memory layouts for which the corresponding
	85	* header bit is in the init state.
	86	*/
	87	while (xstate_bv) {
	88	if (xstate_bv & 0x1) {
	89	int offset = xstate_offsets[feature_bit];
	90	int size = xstate_sizes[feature_bit];
	91
	92	memcpy(((void *) fx) + offset,
	93	((void *) init_xstate_buf) + offset,
	94	size);
	95	}
	96
	97	xstate_bv >>= 1;
	98	feature_bit++;
	99	}
	100	}
	101
c37b5efe SS	102	/*
	103	* Check for the presence of extended state information in the
	104	* user fpstate pointer in the sigcontext.
	105	*/
	106	int check_for_xstate(struct i387_fxsave_struct __user *buf,
	107	void __user *fpstate,
	108	struct _fpx_sw_bytes *fx_sw_user)
	109	{
	110	int min_xstate_size = sizeof(struct i387_fxsave_struct) +
	111	sizeof(struct xsave_hdr_struct);
	112	unsigned int magic2;
	113	int err;
	114
	115	err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0],
	116	sizeof(struct _fpx_sw_bytes));
c37b5efe	117	if (err)
d6d4d420	118	return -EFAULT;
c37b5efe SS	119
	120	/*
	121	* First Magic check failed.
	122	*/
	123	if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1)
d6d4d420	124	return -EINVAL;
c37b5efe SS	125
	126	/*
	127	* Check for error scenarios.
	128	*/
	129	if (fx_sw_user->xstate_size < min_xstate_size \|\|
	130	fx_sw_user->xstate_size > xstate_size \|\|
	131	fx_sw_user->xstate_size > fx_sw_user->extended_size)
d6d4d420	132	return -EINVAL;
c37b5efe SS	133
	134	err = __get_user(magic2, (__u32 ) (((void )fpstate) +
	135	fx_sw_user->extended_size -
	136	FP_XSTATE_MAGIC2_SIZE));
d6d4d420 DC	137	if (err)
d6d4d420 DC	138	return err;
c37b5efe SS	139	/*
	140	* Check for the presence of second magic word at the end of memory
	141	* layout. This detects the case where the user just copied the legacy
	142	* fpstate layout with out copying the extended state information
	143	* in the memory layout.
	144	*/
d6d4d420 DC	145	if (magic2 != FP_XSTATE_MAGIC2)
d6d4d420 DC	146	return -EFAULT;
c37b5efe SS	147
	148	return 0;
	149	}
	150
ab513701 SS	151	#ifdef CONFIG_X86_64
	152	/*
	153	* Signal frame handlers.
	154	*/
	155
	156	int save_i387_xstate(void __user *buf)
	157	{
	158	struct task_struct *tsk = current;
	159	int err = 0;
	160
	161	if (!access_ok(VERIFY_WRITE, buf, sig_xstate_size))
	162	return -EACCES;
	163
f65bc214	164	BUG_ON(sig_xstate_size < xstate_size);
ab513701	165
c37b5efe	166	if ((unsigned long)buf % 64)
ab513701 SS	167	printk("save_i387_xstate: bad fpstate %p\n", buf);
	168
	169	if (!used_math())
	170	return 0;
06c38d5e	171
15d8791c	172	if (user_has_fpu()) {
c9ad4882	173	if (use_xsave())
c37b5efe SS	174	err = xsave_user(buf);
	175	else
	176	err = fxsave_user(buf);
	177
ab513701 SS	178	if (err)
ab513701 SS	179	return err;
15d8791c	180	user_fpu_end();
ab513701	181	} else {
29104e10	182	sanitize_i387_state(tsk);
86603283	183	if (__copy_to_user(buf, &tsk->thread.fpu.state->fxsave,
ab513701 SS	184	xstate_size))
	185	return -1;
	186	}
c37b5efe	187
06c38d5e SS	188	clear_used_math(); /* trigger finit */
06c38d5e SS	189
c9ad4882	190	if (use_xsave()) {
c37b5efe	191	struct _fpstate __user *fx = buf;
04944b79 SS	192	struct _xstate __user *x = buf;
04944b79 SS	193	u64 xstate_bv;
c37b5efe SS	194
	195	err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved,
	196	sizeof(struct _fpx_sw_bytes));
	197
	198	err \|= __put_user(FP_XSTATE_MAGIC2,
	199	(__u32 __user *) (buf + sig_xstate_size
	200	- FP_XSTATE_MAGIC2_SIZE));
04944b79 SS	201
	202	/*
	203	* Read the xstate_bv which we copied (directly from the cpu or
	204	* from the state in task struct) to the user buffers and
	205	* set the FP/SSE bits.
	206	*/
	207	err \|= __get_user(xstate_bv, &x->xstate_hdr.xstate_bv);
	208
	209	/*
	210	* For legacy compatible, we always set FP/SSE bits in the bit
	211	* vector while saving the state to the user context. This will
	212	* enable us capturing any changes(during sigreturn) to
	213	* the FP/SSE bits by the legacy applications which don't touch
	214	* xstate_bv in the xsave header.
	215	*
	216	* xsave aware apps can change the xstate_bv in the xsave
	217	* header as well as change any contents in the memory layout.
	218	* xrestore as part of sigreturn will capture all the changes.
	219	*/
	220	xstate_bv \|= XSTATE_FPSSE;
	221
	222	err \|= __put_user(xstate_bv, &x->xstate_hdr.xstate_bv);
	223
f364eada SS	224	if (err)
f364eada SS	225	return err;
c37b5efe SS	226	}
c37b5efe SS	227
ab513701 SS	228	return 1;
	229	}
	230
c37b5efe SS	231	/*
	232	* Restore the extended state if present. Otherwise, restore the FP/SSE
	233	* state.
	234	*/
7820b756	235	static int restore_user_xstate(void __user *buf)
c37b5efe SS	236	{
c37b5efe SS	237	struct _fpx_sw_bytes fx_sw_user;
6152e4b1	238	u64 mask;
c37b5efe SS	239	int err;
	240
	241	if (((unsigned long)buf % 64) \|\|
	242	check_for_xstate(buf, buf, &fx_sw_user))
	243	goto fx_only;
	244
6152e4b1	245	mask = fx_sw_user.xstate_bv;
c37b5efe SS	246
	247	/*
	248	* restore the state passed by the user.
	249	*/
6152e4b1	250	err = xrestore_user(buf, mask);
c37b5efe SS	251	if (err)
	252	return err;
	253
	254	/*
	255	* init the state skipped by the user.
	256	*/
6152e4b1	257	mask = pcntxt_mask & ~mask;
8e221b6d SS	258	if (unlikely(mask))
8e221b6d SS	259	xrstor_state(init_xstate_buf, mask);
c37b5efe SS	260
	261	return 0;
	262
	263	fx_only:
	264	/*
	265	* couldn't find the extended state information in the
	266	* memory layout. Restore just the FP/SSE and init all
	267	* the other extended state.
	268	*/
6152e4b1	269	xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE);
c37b5efe SS	270	return fxrstor_checking((__force struct i387_fxsave_struct *)buf);
	271	}
	272
ab513701 SS	273	/*
	274	* This restores directly out of user space. Exceptions are handled.
	275	*/
	276	int restore_i387_xstate(void __user *buf)
	277	{
	278	struct task_struct *tsk = current;
c37b5efe	279	int err = 0;
ab513701 SS	280
ab513701 SS	281	if (!buf) {
c37b5efe SS	282	if (used_math())
c37b5efe SS	283	goto clear;
ab513701 SS	284	return 0;
	285	} else
	286	if (!access_ok(VERIFY_READ, buf, sig_xstate_size))
	287	return -EACCES;
	288
	289	if (!used_math()) {
	290	err = init_fpu(tsk);
	291	if (err)
	292	return err;
	293	}
	294
15d8791c	295	user_fpu_begin();
c9ad4882	296	if (use_xsave())
c37b5efe SS	297	err = restore_user_xstate(buf);
	298	else
	299	err = fxrstor_checking((__force struct i387_fxsave_struct *)
	300	buf);
ab513701 SS	301	if (unlikely(err)) {
	302	/*
	303	* Encountered an error while doing the restore from the
	304	* user buffer, clear the fpu state.
	305	*/
c37b5efe	306	clear:
ab513701 SS	307	clear_fpu(tsk);
	308	clear_used_math();
	309	}
	310	return err;
	311	}
	312	#endif
	313
c37b5efe SS	314	/*
	315	* Prepare the SW reserved portion of the fxsave memory layout, indicating
	316	* the presence of the extended state information in the memory layout
	317	* pointed by the fpstate pointer in the sigcontext.
	318	* This will be saved when ever the FP and extended state context is
	319	* saved on the user stack during the signal handler delivery to the user.
	320	*/
8bcad30f	321	static void prepare_fx_sw_frame(void)
c37b5efe SS	322	{
	323	int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) +
	324	FP_XSTATE_MAGIC2_SIZE;
	325
	326	sig_xstate_size = sizeof(struct _fpstate) + size_extended;
	327
	328	#ifdef CONFIG_IA32_EMULATION
	329	sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended;
	330	#endif
	331
	332	memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved));
	333
	334	fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
	335	fx_sw_reserved.extended_size = sig_xstate_size;
6152e4b1	336	fx_sw_reserved.xstate_bv = pcntxt_mask;
c37b5efe SS	337	fx_sw_reserved.xstate_size = xstate_size;
	338	#ifdef CONFIG_IA32_EMULATION
	339	memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved,
	340	sizeof(struct _fpx_sw_bytes));
	341	fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size;
	342	#endif
	343	}
	344
3c1c7f10 SS	345	#ifdef CONFIG_X86_64
	346	unsigned int sig_xstate_size = sizeof(struct _fpstate);
	347	#endif
	348
dc1e35c6 SS	349	/*
	350	* Enable the extended processor state save/restore feature
	351	*/
1cff92d8	352	static inline void xstate_enable(void)
dc1e35c6	353	{
dc1e35c6	354	set_in_cr4(X86_CR4_OSXSAVE);
6152e4b1	355	xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask);
dc1e35c6 SS	356	}
dc1e35c6 SS	357
a1488f8b SS	358	/*
	359	* Record the offsets and sizes of different state managed by the xsave
	360	* memory layout.
	361	*/
4995b9db	362	static void __init setup_xstate_features(void)
a1488f8b SS	363	{
	364	int eax, ebx, ecx, edx, leaf = 0x2;
	365
	366	xstate_features = fls64(pcntxt_mask);
	367	xstate_offsets = alloc_bootmem(xstate_features * sizeof(int));
	368	xstate_sizes = alloc_bootmem(xstate_features * sizeof(int));
	369
	370	do {
ee813d53	371	cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx);
a1488f8b SS	372
	373	if (eax == 0)
	374	break;
	375
	376	xstate_offsets[leaf] = ebx;
	377	xstate_sizes[leaf] = eax;
	378
	379	leaf++;
	380	} while (1);
	381	}
	382
dc1e35c6 SS	383	/*
	384	* setup the xstate image representing the init state
	385	*/
a19aac85	386	static void __init setup_xstate_init(void)
dc1e35c6	387	{
29104e10 SS	388	setup_xstate_features();
	389
	390	/*
	391	* Setup init_xstate_buf to represent the init state of
	392	* all the features managed by the xsave
	393	*/
10340ae1 SS	394	init_xstate_buf = alloc_bootmem_align(xstate_size,
10340ae1 SS	395	__alignof__(struct xsave_struct));
dc1e35c6	396	init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;
a1488f8b	397
29104e10 SS	398	clts();
	399	/*
	400	* Init all the features state with header_bv being 0x0
	401	*/
	402	xrstor_state(init_xstate_buf, -1);
	403	/*
	404	* Dump the init state again. This is to identify the init state
	405	* of any feature which is not represented by all zero's.
	406	*/
	407	xsave_state(init_xstate_buf, -1);
	408	stts();
dc1e35c6 SS	409	}
	410
	411	/*
	412	* Enable and initialize the xsave feature.
	413	*/
1cff92d8	414	static void __init xstate_enable_boot_cpu(void)
dc1e35c6 SS	415	{
	416	unsigned int eax, ebx, ecx, edx;
	417
ee813d53 RR	418	if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
	419	WARN(1, KERN_ERR "XSTATE_CPUID missing\n");
	420	return;
	421	}
	422
	423	cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
6152e4b1	424	pcntxt_mask = eax + ((u64)edx << 32);
dc1e35c6	425
6152e4b1 PA	426	if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) {
	427	printk(KERN_ERR "FP/SSE not shown under xsave features 0x%llx\n",
	428	pcntxt_mask);
dc1e35c6 SS	429	BUG();
	430	}
	431
	432	/*
a30469e7	433	* Support only the state known to OS.
dc1e35c6	434	*/
6152e4b1	435	pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
97e80a70	436
1cff92d8	437	xstate_enable();
dc1e35c6 SS	438
	439	/*
	440	* Recompute the context size for enabled features
	441	*/
ee813d53	442	cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
dc1e35c6 SS	443	xstate_size = ebx;
dc1e35c6 SS	444
5b3efd50	445	update_regset_xstate_info(xstate_size, pcntxt_mask);
c37b5efe SS	446	prepare_fx_sw_frame();
c37b5efe SS	447
dc1e35c6 SS	448	setup_xstate_init();
dc1e35c6 SS	449
6152e4b1	450	printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%llx, "
dc1e35c6	451	"cntxt size 0x%x\n",
6152e4b1	452	pcntxt_mask, xstate_size);
dc1e35c6	453	}
82d4150c	454
1cff92d8 PA	455	/*
	456	* For the very first instance, this calls xstate_enable_boot_cpu();
	457	* for all subsequent instances, this calls xstate_enable().
	458	*
	459	* This is somewhat obfuscated due to the lack of powerful enough
	460	* overrides for the section checks.
	461	*/
82d4150c RR	462	void __cpuinit xsave_init(void)
82d4150c RR	463	{
1cff92d8 PA	464	static __refdata void (*next_func)(void) = xstate_enable_boot_cpu;
	465	void (*this_func)(void);
	466
0e49bf66 RR	467	if (!cpu_has_xsave)
	468	return;
	469
1cff92d8 PA	470	this_func = next_func;
	471	next_func = xstate_enable;
	472	this_func();
82d4150c	473	}