[deliverable/linux.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;

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