[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>
#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(task_thread_info(tsk)->status & TS_USEDFPU);

	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 upto 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 (task_thread_info(tsk)->status & TS_USEDFPU) {
		/*
	 	 * Start with clearing the user buffer. This will present a
	 	 * clean context for the bytes not touched by the fxsave/xsave.
		 */
		err = __clear_user(buf, sig_xstate_size);
		if (err)
			return err;

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

		if (err)
			return err;
		task_thread_info(tsk)->status &= ~TS_USEDFPU;
		stts();
	} 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;

	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;
	}

	if (!(task_thread_info(current)->status & TS_USEDFPU)) {
		clts();
		task_thread_info(current)->status |= TS_USEDFPU;
	}
	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(u64 mask)
{
	set_in_cr4(X86_CR4_OSXSAVE);
	xsetbv(XCR_XFEATURE_ENABLED_MASK, mask);
}

/*
 * Record the offsets and sizes of different state managed by the xsave
 * memory layout.
 */
static void 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(xstate_size);
	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 __cpuinit 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(pcntxt_mask);

	/*
	 * 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);
}

void __cpuinit xsave_init(void)
{
	if (!cpu_has_xsave)
		return;

	/*
	 * Boot processor to setup the FP and extended state context info.
	 */
	if (!smp_processor_id())
		xstate_enable_boot_cpu();
	else
		xstate_enable(pcntxt_mask);
}
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>
c37b5efe SS	9	#ifdef CONFIG_IA32_EMULATION
	10	#include <asm/sigcontext32.h>
	11	#endif
6152e4b1	12	#include <asm/xcr.h>
dc1e35c6 SS	13
	14	/*
	15	* Supported feature mask by the CPU and the kernel.
	16	*/
6152e4b1	17	u64 pcntxt_mask;
dc1e35c6	18
45c2d7f4 RR	19	/*
	20	* Represents init state for the supported extended state.
	21	*/
	22	static struct xsave_struct *init_xstate_buf;
	23
c37b5efe SS	24	struct _fpx_sw_bytes fx_sw_reserved;
	25	#ifdef CONFIG_IA32_EMULATION
	26	struct _fpx_sw_bytes fx_sw_reserved_ia32;
	27	#endif
	28
a1488f8b SS	29	static unsigned int xstate_offsets, xstate_sizes, xstate_features;
a1488f8b SS	30
29104e10 SS	31	/*
	32	* If a processor implementation discern that a processor state component is
	33	* in its initialized state it may modify the corresponding bit in the
	34	* xsave_hdr.xstate_bv as '0', with out modifying the corresponding memory
	35	* layout in the case of xsaveopt. While presenting the xstate information to
	36	* the user, we always ensure that the memory layout of a feature will be in
	37	* the init state if the corresponding header bit is zero. This is to ensure
	38	* that the user doesn't see some stale state in the memory layout during
	39	* signal handling, debugging etc.
	40	*/
	41	void __sanitize_i387_state(struct task_struct *tsk)
	42	{
	43	u64 xstate_bv;
	44	int feature_bit = 0x2;
	45	struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave;
	46
	47	if (!fx)
	48	return;
	49
	50	BUG_ON(task_thread_info(tsk)->status & TS_USEDFPU);
	51
	52	xstate_bv = tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv;
	53
	54	/*
	55	* None of the feature bits are in init state. So nothing else
	56	* to do for us, as the memory layout is upto date.
	57	*/
	58	if ((xstate_bv & pcntxt_mask) == pcntxt_mask)
	59	return;
	60
	61	/*
	62	* FP is in init state
	63	*/
	64	if (!(xstate_bv & XSTATE_FP)) {
	65	fx->cwd = 0x37f;
	66	fx->swd = 0;
	67	fx->twd = 0;
	68	fx->fop = 0;
	69	fx->rip = 0;
	70	fx->rdp = 0;
	71	memset(&fx->st_space[0], 0, 128);
	72	}
	73
	74	/*
	75	* SSE is in init state
	76	*/
	77	if (!(xstate_bv & XSTATE_SSE))
	78	memset(&fx->xmm_space[0], 0, 256);
	79
	80	xstate_bv = (pcntxt_mask & ~xstate_bv) >> 2;
	81
	82	/*
	83	* Update all the other memory layouts for which the corresponding
	84	* header bit is in the init state.
	85	*/
	86	while (xstate_bv) {
	87	if (xstate_bv & 0x1) {
	88	int offset = xstate_offsets[feature_bit];
	89	int size = xstate_sizes[feature_bit];
	90
	91	memcpy(((void *) fx) + offset,
	92	((void *) init_xstate_buf) + offset,
	93	size);
	94	}
95
96	xstate_bv >>= 1;
97	feature_bit++;
98	}
99	}
100
c37b5efe SS	101	/*
	102	* Check for the presence of extended state information in the
	103	* user fpstate pointer in the sigcontext.
	104	*/
	105	int check_for_xstate(struct i387_fxsave_struct __user *buf,
	106	void __user *fpstate,
	107	struct _fpx_sw_bytes *fx_sw_user)
	108	{
	109	int min_xstate_size = sizeof(struct i387_fxsave_struct) +
	110	sizeof(struct xsave_hdr_struct);
	111	unsigned int magic2;
	112	int err;
	113
	114	err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0],
	115	sizeof(struct _fpx_sw_bytes));
c37b5efe	116	if (err)
d6d4d420	117	return -EFAULT;
c37b5efe SS	118
	119	/*
	120	* First Magic check failed.
	121	*/
	122	if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1)
d6d4d420	123	return -EINVAL;
c37b5efe SS	124
	125	/*
	126	* Check for error scenarios.
	127	*/
	128	if (fx_sw_user->xstate_size < min_xstate_size \|\|
	129	fx_sw_user->xstate_size > xstate_size \|\|
	130	fx_sw_user->xstate_size > fx_sw_user->extended_size)
d6d4d420	131	return -EINVAL;
c37b5efe SS	132
	133	err = __get_user(magic2, (__u32 ) (((void )fpstate) +
	134	fx_sw_user->extended_size -
	135	FP_XSTATE_MAGIC2_SIZE));
d6d4d420 DC	136	if (err)
d6d4d420 DC	137	return err;
c37b5efe SS	138	/*
	139	* Check for the presence of second magic word at the end of memory
	140	* layout. This detects the case where the user just copied the legacy
	141	* fpstate layout with out copying the extended state information
	142	* in the memory layout.
	143	*/
d6d4d420 DC	144	if (magic2 != FP_XSTATE_MAGIC2)
d6d4d420 DC	145	return -EFAULT;
c37b5efe SS	146
	147	return 0;
	148	}
	149
ab513701 SS	150	#ifdef CONFIG_X86_64
	151	/*
	152	* Signal frame handlers.
	153	*/
	154
	155	int save_i387_xstate(void __user *buf)
	156	{
	157	struct task_struct *tsk = current;
	158	int err = 0;
	159
	160	if (!access_ok(VERIFY_WRITE, buf, sig_xstate_size))
	161	return -EACCES;
	162
f65bc214	163	BUG_ON(sig_xstate_size < xstate_size);
ab513701	164
c37b5efe	165	if ((unsigned long)buf % 64)
ab513701 SS	166	printk("save_i387_xstate: bad fpstate %p\n", buf);
	167
	168	if (!used_math())
	169	return 0;
06c38d5e	170
ab513701	171	if (task_thread_info(tsk)->status & TS_USEDFPU) {
ed405958 SS	172	/*
	173	* Start with clearing the user buffer. This will present a
	174	* clean context for the bytes not touched by the fxsave/xsave.
	175	*/
9f482807 IM	176	err = __clear_user(buf, sig_xstate_size);
	177	if (err)
	178	return err;
ed405958	179
c9ad4882	180	if (use_xsave())
c37b5efe SS	181	err = xsave_user(buf);
	182	else
	183	err = fxsave_user(buf);
	184
ab513701 SS	185	if (err)
	186	return err;
	187	task_thread_info(tsk)->status &= ~TS_USEDFPU;
	188	stts();
	189	} else {
29104e10	190	sanitize_i387_state(tsk);
86603283	191	if (__copy_to_user(buf, &tsk->thread.fpu.state->fxsave,
ab513701 SS	192	xstate_size))
	193	return -1;
	194	}
c37b5efe	195
06c38d5e SS	196	clear_used_math(); /* trigger finit */
06c38d5e SS	197
c9ad4882	198	if (use_xsave()) {
c37b5efe	199	struct _fpstate __user *fx = buf;
04944b79 SS	200	struct _xstate __user *x = buf;
04944b79 SS	201	u64 xstate_bv;
c37b5efe SS	202
	203	err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved,
	204	sizeof(struct _fpx_sw_bytes));
	205
	206	err \|= __put_user(FP_XSTATE_MAGIC2,
	207	(__u32 __user *) (buf + sig_xstate_size
	208	- FP_XSTATE_MAGIC2_SIZE));
04944b79 SS	209
	210	/*
	211	* Read the xstate_bv which we copied (directly from the cpu or
	212	* from the state in task struct) to the user buffers and
	213	* set the FP/SSE bits.
	214	*/
	215	err \|= __get_user(xstate_bv, &x->xstate_hdr.xstate_bv);
	216
	217	/*
	218	* For legacy compatible, we always set FP/SSE bits in the bit
	219	* vector while saving the state to the user context. This will
	220	* enable us capturing any changes(during sigreturn) to
	221	* the FP/SSE bits by the legacy applications which don't touch
	222	* xstate_bv in the xsave header.
	223	*
	224	* xsave aware apps can change the xstate_bv in the xsave
	225	* header as well as change any contents in the memory layout.
	226	* xrestore as part of sigreturn will capture all the changes.
	227	*/
	228	xstate_bv \|= XSTATE_FPSSE;
	229
	230	err \|= __put_user(xstate_bv, &x->xstate_hdr.xstate_bv);
	231
f364eada SS	232	if (err)
f364eada SS	233	return err;
c37b5efe SS	234	}
c37b5efe SS	235
ab513701 SS	236	return 1;
	237	}
	238
c37b5efe SS	239	/*
	240	* Restore the extended state if present. Otherwise, restore the FP/SSE
	241	* state.
	242	*/
7820b756	243	static int restore_user_xstate(void __user *buf)
c37b5efe SS	244	{
c37b5efe SS	245	struct _fpx_sw_bytes fx_sw_user;
6152e4b1	246	u64 mask;
c37b5efe SS	247	int err;
	248
	249	if (((unsigned long)buf % 64) \|\|
	250	check_for_xstate(buf, buf, &fx_sw_user))
	251	goto fx_only;
	252
6152e4b1	253	mask = fx_sw_user.xstate_bv;
c37b5efe SS	254
	255	/*
	256	* restore the state passed by the user.
	257	*/
6152e4b1	258	err = xrestore_user(buf, mask);
c37b5efe SS	259	if (err)
	260	return err;
	261
	262	/*
	263	* init the state skipped by the user.
	264	*/
6152e4b1	265	mask = pcntxt_mask & ~mask;
c37b5efe	266
6152e4b1	267	xrstor_state(init_xstate_buf, mask);
c37b5efe SS	268
	269	return 0;
	270
	271	fx_only:
	272	/*
	273	* couldn't find the extended state information in the
	274	* memory layout. Restore just the FP/SSE and init all
	275	* the other extended state.
	276	*/
6152e4b1	277	xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE);
c37b5efe SS	278	return fxrstor_checking((__force struct i387_fxsave_struct *)buf);
	279	}
	280
ab513701 SS	281	/*
	282	* This restores directly out of user space. Exceptions are handled.
	283	*/
	284	int restore_i387_xstate(void __user *buf)
	285	{
	286	struct task_struct *tsk = current;
c37b5efe	287	int err = 0;
ab513701 SS	288
ab513701 SS	289	if (!buf) {
c37b5efe SS	290	if (used_math())
c37b5efe SS	291	goto clear;
ab513701 SS	292	return 0;
	293	} else
	294	if (!access_ok(VERIFY_READ, buf, sig_xstate_size))
	295	return -EACCES;
	296
	297	if (!used_math()) {
	298	err = init_fpu(tsk);
	299	if (err)
	300	return err;
	301	}
	302
	303	if (!(task_thread_info(current)->status & TS_USEDFPU)) {
	304	clts();
	305	task_thread_info(current)->status \|= TS_USEDFPU;
	306	}
c9ad4882	307	if (use_xsave())
c37b5efe SS	308	err = restore_user_xstate(buf);
	309	else
	310	err = fxrstor_checking((__force struct i387_fxsave_struct *)
	311	buf);
ab513701 SS	312	if (unlikely(err)) {
	313	/*
	314	* Encountered an error while doing the restore from the
	315	* user buffer, clear the fpu state.
	316	*/
c37b5efe	317	clear:
ab513701 SS	318	clear_fpu(tsk);
	319	clear_used_math();
	320	}
	321	return err;
	322	}
	323	#endif
	324
c37b5efe SS	325	/*
	326	* Prepare the SW reserved portion of the fxsave memory layout, indicating
	327	* the presence of the extended state information in the memory layout
	328	* pointed by the fpstate pointer in the sigcontext.
	329	* This will be saved when ever the FP and extended state context is
	330	* saved on the user stack during the signal handler delivery to the user.
	331	*/
8bcad30f	332	static void prepare_fx_sw_frame(void)
c37b5efe SS	333	{
	334	int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) +
	335	FP_XSTATE_MAGIC2_SIZE;
	336
	337	sig_xstate_size = sizeof(struct _fpstate) + size_extended;
	338
	339	#ifdef CONFIG_IA32_EMULATION
	340	sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended;
	341	#endif
	342
	343	memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved));
	344
	345	fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
	346	fx_sw_reserved.extended_size = sig_xstate_size;
6152e4b1	347	fx_sw_reserved.xstate_bv = pcntxt_mask;
c37b5efe SS	348	fx_sw_reserved.xstate_size = xstate_size;
	349	#ifdef CONFIG_IA32_EMULATION
	350	memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved,
	351	sizeof(struct _fpx_sw_bytes));
	352	fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size;
	353	#endif
	354	}
	355
3c1c7f10 SS	356	#ifdef CONFIG_X86_64
	357	unsigned int sig_xstate_size = sizeof(struct _fpstate);
	358	#endif
	359
dc1e35c6 SS	360	/*
	361	* Enable the extended processor state save/restore feature
	362	*/
97e80a70	363	static inline void xstate_enable(u64 mask)
dc1e35c6	364	{
dc1e35c6	365	set_in_cr4(X86_CR4_OSXSAVE);
97e80a70	366	xsetbv(XCR_XFEATURE_ENABLED_MASK, mask);
dc1e35c6 SS	367	}
dc1e35c6 SS	368
a1488f8b SS	369	/*
	370	* Record the offsets and sizes of different state managed by the xsave
	371	* memory layout.
	372	*/
	373	static void setup_xstate_features(void)
	374	{
	375	int eax, ebx, ecx, edx, leaf = 0x2;
	376
	377	xstate_features = fls64(pcntxt_mask);
	378	xstate_offsets = alloc_bootmem(xstate_features * sizeof(int));
	379	xstate_sizes = alloc_bootmem(xstate_features * sizeof(int));
	380
	381	do {
ee813d53	382	cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx);
a1488f8b SS	383
	384	if (eax == 0)
	385	break;
	386
	387	xstate_offsets[leaf] = ebx;
	388	xstate_sizes[leaf] = eax;
	389
	390	leaf++;
	391	} while (1);
	392	}
	393
dc1e35c6 SS	394	/*
	395	* setup the xstate image representing the init state
	396	*/
a19aac85	397	static void __init setup_xstate_init(void)
dc1e35c6	398	{
29104e10 SS	399	setup_xstate_features();
	400
	401	/*
	402	* Setup init_xstate_buf to represent the init state of
	403	* all the features managed by the xsave
	404	*/
dc1e35c6 SS	405	init_xstate_buf = alloc_bootmem(xstate_size);
dc1e35c6 SS	406	init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;
a1488f8b	407
29104e10 SS	408	clts();
	409	/*
	410	* Init all the features state with header_bv being 0x0
	411	*/
	412	xrstor_state(init_xstate_buf, -1);
	413	/*
	414	* Dump the init state again. This is to identify the init state
	415	* of any feature which is not represented by all zero's.
	416	*/
	417	xsave_state(init_xstate_buf, -1);
	418	stts();
dc1e35c6 SS	419	}
	420
	421	/*
	422	* Enable and initialize the xsave feature.
	423	*/
97e80a70	424	static void __cpuinit xstate_enable_boot_cpu(void)
dc1e35c6 SS	425	{
	426	unsigned int eax, ebx, ecx, edx;
	427
ee813d53 RR	428	if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
	429	WARN(1, KERN_ERR "XSTATE_CPUID missing\n");
	430	return;
	431	}
	432
	433	cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
6152e4b1	434	pcntxt_mask = eax + ((u64)edx << 32);
dc1e35c6	435
6152e4b1 PA	436	if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) {
	437	printk(KERN_ERR "FP/SSE not shown under xsave features 0x%llx\n",
	438	pcntxt_mask);
dc1e35c6 SS	439	BUG();
	440	}
	441
	442	/*
a30469e7	443	* Support only the state known to OS.
dc1e35c6	444	*/
6152e4b1	445	pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
97e80a70 RR	446
97e80a70 RR	447	xstate_enable(pcntxt_mask);
dc1e35c6 SS	448
	449	/*
	450	* Recompute the context size for enabled features
	451	*/
ee813d53	452	cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
dc1e35c6 SS	453	xstate_size = ebx;
dc1e35c6 SS	454
5b3efd50	455	update_regset_xstate_info(xstate_size, pcntxt_mask);
c37b5efe SS	456	prepare_fx_sw_frame();
c37b5efe SS	457
dc1e35c6 SS	458	setup_xstate_init();
dc1e35c6 SS	459
6152e4b1	460	printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%llx, "
dc1e35c6	461	"cntxt size 0x%x\n",
6152e4b1	462	pcntxt_mask, xstate_size);
dc1e35c6	463	}
82d4150c RR	464
	465	void __cpuinit xsave_init(void)
	466	{
0e49bf66 RR	467	if (!cpu_has_xsave)
	468	return;
	469
82d4150c RR	470	/*
	471	* Boot processor to setup the FP and extended state context info.
	472	*/
	473	if (!smp_processor_id())
97e80a70 RR	474	xstate_enable_boot_cpu();
	475	else
	476	xstate_enable(pcntxt_mask);
82d4150c	477	}