[linux-2.6-block.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;

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

/*
 * 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 err;

	/*
	 * First Magic check failed.
	 */
	if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1)
		return -1;

	/*
	 * 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 -1;

	err = __get_user(magic2, (__u32 *) (((void *)fpstate) +
					    fx_sw_user->extended_size -
					    FP_XSTATE_MAGIC2_SIZE));
	/*
	 * 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 (err || magic2 != FP_XSTATE_MAGIC2)
		return -1;

	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;
	clear_used_math(); /* trigger finit */
	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 (task_thread_info(tsk)->status & TS_XSAVE)
			err = xsave_user(buf);
		else
			err = fxsave_user(buf);

		if (err)
			return err;
		task_thread_info(tsk)->status &= ~TS_USEDFPU;
		stts();
	} else {
		if (__copy_to_user(buf, &tsk->thread.xstate->fxsave,
				   xstate_size))
			return -1;
	}

	if (task_thread_info(tsk)->status & TS_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.
 */
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 (task_thread_info(tsk)->status & TS_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
}

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

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

/*
 * Enable the extended processor state save/restore feature
 */
void __cpuinit xsave_init(void)
{
	if (!cpu_has_xsave)
		return;

	set_in_cr4(X86_CR4_OSXSAVE);

	/*
	 * Enable all the features that the HW is capable of
	 * and the Linux kernel is aware of.
	 */
	xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask);
}

/*
 * setup the xstate image representing the init state
 */
static void __init setup_xstate_init(void)
{
	init_xstate_buf = alloc_bootmem(xstate_size);
	init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;
}

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

	cpuid_count(0xd, 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();
	}

	/*
	 * for now OS knows only about FP/SSE
	 */
	pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
	xsave_init();

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

	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);
}
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
c37b5efe SS	19	struct _fpx_sw_bytes fx_sw_reserved;
	20	#ifdef CONFIG_IA32_EMULATION
	21	struct _fpx_sw_bytes fx_sw_reserved_ia32;
	22	#endif
	23
	24	/*
	25	* Check for the presence of extended state information in the
	26	* user fpstate pointer in the sigcontext.
	27	*/
	28	int check_for_xstate(struct i387_fxsave_struct __user *buf,
	29	void __user *fpstate,
	30	struct _fpx_sw_bytes *fx_sw_user)
	31	{
	32	int min_xstate_size = sizeof(struct i387_fxsave_struct) +
	33	sizeof(struct xsave_hdr_struct);
	34	unsigned int magic2;
	35	int err;
	36
	37	err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0],
	38	sizeof(struct _fpx_sw_bytes));
	39
	40	if (err)
	41	return err;
	42
	43	/*
	44	* First Magic check failed.
	45	*/
	46	if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1)
	47	return -1;
	48
	49	/*
	50	* Check for error scenarios.
	51	*/
	52	if (fx_sw_user->xstate_size < min_xstate_size \|\|
	53	fx_sw_user->xstate_size > xstate_size \|\|
	54	fx_sw_user->xstate_size > fx_sw_user->extended_size)
	55	return -1;
	56
	57	err = __get_user(magic2, (__u32 ) (((void )fpstate) +
	58	fx_sw_user->extended_size -
	59	FP_XSTATE_MAGIC2_SIZE));
	60	/*
	61	* Check for the presence of second magic word at the end of memory
	62	* layout. This detects the case where the user just copied the legacy
	63	* fpstate layout with out copying the extended state information
	64	* in the memory layout.
	65	*/
	66	if (err \|\| magic2 != FP_XSTATE_MAGIC2)
	67	return -1;
	68
	69	return 0;
	70	}
	71
ab513701 SS	72	#ifdef CONFIG_X86_64
	73	/*
	74	* Signal frame handlers.
	75	*/
	76
	77	int save_i387_xstate(void __user *buf)
	78	{
	79	struct task_struct *tsk = current;
	80	int err = 0;
	81
	82	if (!access_ok(VERIFY_WRITE, buf, sig_xstate_size))
	83	return -EACCES;
	84
f65bc214	85	BUG_ON(sig_xstate_size < xstate_size);
ab513701	86
c37b5efe	87	if ((unsigned long)buf % 64)
ab513701 SS	88	printk("save_i387_xstate: bad fpstate %p\n", buf);
	89
	90	if (!used_math())
	91	return 0;
	92	clear_used_math(); /* trigger finit */
	93	if (task_thread_info(tsk)->status & TS_USEDFPU) {
ed405958 SS	94	/*
	95	* Start with clearing the user buffer. This will present a
	96	* clean context for the bytes not touched by the fxsave/xsave.
	97	*/
9f482807 IM	98	err = __clear_user(buf, sig_xstate_size);
	99	if (err)
	100	return err;
ed405958	101
c37b5efe SS	102	if (task_thread_info(tsk)->status & TS_XSAVE)
	103	err = xsave_user(buf);
	104	else
	105	err = fxsave_user(buf);
	106
ab513701 SS	107	if (err)
	108	return err;
	109	task_thread_info(tsk)->status &= ~TS_USEDFPU;
	110	stts();
	111	} else {
	112	if (__copy_to_user(buf, &tsk->thread.xstate->fxsave,
	113	xstate_size))
	114	return -1;
	115	}
c37b5efe SS	116
	117	if (task_thread_info(tsk)->status & TS_XSAVE) {
	118	struct _fpstate __user *fx = buf;
04944b79 SS	119	struct _xstate __user *x = buf;
04944b79 SS	120	u64 xstate_bv;
c37b5efe SS	121
	122	err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved,
	123	sizeof(struct _fpx_sw_bytes));
	124
	125	err \|= __put_user(FP_XSTATE_MAGIC2,
	126	(__u32 __user *) (buf + sig_xstate_size
	127	- FP_XSTATE_MAGIC2_SIZE));
04944b79 SS	128
	129	/*
	130	* Read the xstate_bv which we copied (directly from the cpu or
	131	* from the state in task struct) to the user buffers and
	132	* set the FP/SSE bits.
	133	*/
	134	err \|= __get_user(xstate_bv, &x->xstate_hdr.xstate_bv);
	135
	136	/*
	137	* For legacy compatible, we always set FP/SSE bits in the bit
	138	* vector while saving the state to the user context. This will
	139	* enable us capturing any changes(during sigreturn) to
	140	* the FP/SSE bits by the legacy applications which don't touch
	141	* xstate_bv in the xsave header.
	142	*
	143	* xsave aware apps can change the xstate_bv in the xsave
	144	* header as well as change any contents in the memory layout.
	145	* xrestore as part of sigreturn will capture all the changes.
	146	*/
	147	xstate_bv \|= XSTATE_FPSSE;
	148
	149	err \|= __put_user(xstate_bv, &x->xstate_hdr.xstate_bv);
	150
f364eada SS	151	if (err)
f364eada SS	152	return err;
c37b5efe SS	153	}
c37b5efe SS	154
ab513701 SS	155	return 1;
	156	}
	157
c37b5efe SS	158	/*
	159	* Restore the extended state if present. Otherwise, restore the FP/SSE
	160	* state.
	161	*/
	162	int restore_user_xstate(void __user *buf)
	163	{
	164	struct _fpx_sw_bytes fx_sw_user;
6152e4b1	165	u64 mask;
c37b5efe SS	166	int err;
	167
	168	if (((unsigned long)buf % 64) \|\|
	169	check_for_xstate(buf, buf, &fx_sw_user))
	170	goto fx_only;
	171
6152e4b1	172	mask = fx_sw_user.xstate_bv;
c37b5efe SS	173
	174	/*
	175	* restore the state passed by the user.
	176	*/
6152e4b1	177	err = xrestore_user(buf, mask);
c37b5efe SS	178	if (err)
	179	return err;
	180
	181	/*
	182	* init the state skipped by the user.
	183	*/
6152e4b1	184	mask = pcntxt_mask & ~mask;
c37b5efe	185
6152e4b1	186	xrstor_state(init_xstate_buf, mask);
c37b5efe SS	187
	188	return 0;
	189
	190	fx_only:
	191	/*
	192	* couldn't find the extended state information in the
	193	* memory layout. Restore just the FP/SSE and init all
	194	* the other extended state.
	195	*/
6152e4b1	196	xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE);
c37b5efe SS	197	return fxrstor_checking((__force struct i387_fxsave_struct *)buf);
	198	}
	199
ab513701 SS	200	/*
	201	* This restores directly out of user space. Exceptions are handled.
	202	*/
	203	int restore_i387_xstate(void __user *buf)
	204	{
	205	struct task_struct *tsk = current;
c37b5efe	206	int err = 0;
ab513701 SS	207
ab513701 SS	208	if (!buf) {
c37b5efe SS	209	if (used_math())
c37b5efe SS	210	goto clear;
ab513701 SS	211	return 0;
	212	} else
	213	if (!access_ok(VERIFY_READ, buf, sig_xstate_size))
	214	return -EACCES;
	215
	216	if (!used_math()) {
	217	err = init_fpu(tsk);
	218	if (err)
	219	return err;
	220	}
	221
	222	if (!(task_thread_info(current)->status & TS_USEDFPU)) {
	223	clts();
	224	task_thread_info(current)->status \|= TS_USEDFPU;
	225	}
c37b5efe SS	226	if (task_thread_info(tsk)->status & TS_XSAVE)
	227	err = restore_user_xstate(buf);
	228	else
	229	err = fxrstor_checking((__force struct i387_fxsave_struct *)
	230	buf);
ab513701 SS	231	if (unlikely(err)) {
	232	/*
	233	* Encountered an error while doing the restore from the
	234	* user buffer, clear the fpu state.
	235	*/
c37b5efe	236	clear:
ab513701 SS	237	clear_fpu(tsk);
	238	clear_used_math();
	239	}
	240	return err;
	241	}
	242	#endif
	243
c37b5efe SS	244	/*
	245	* Prepare the SW reserved portion of the fxsave memory layout, indicating
	246	* the presence of the extended state information in the memory layout
	247	* pointed by the fpstate pointer in the sigcontext.
	248	* This will be saved when ever the FP and extended state context is
	249	* saved on the user stack during the signal handler delivery to the user.
	250	*/
8bcad30f	251	static void prepare_fx_sw_frame(void)
c37b5efe SS	252	{
	253	int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) +
	254	FP_XSTATE_MAGIC2_SIZE;
	255
	256	sig_xstate_size = sizeof(struct _fpstate) + size_extended;
	257
	258	#ifdef CONFIG_IA32_EMULATION
	259	sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended;
	260	#endif
	261
	262	memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved));
	263
	264	fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
	265	fx_sw_reserved.extended_size = sig_xstate_size;
6152e4b1	266	fx_sw_reserved.xstate_bv = pcntxt_mask;
c37b5efe SS	267	fx_sw_reserved.xstate_size = xstate_size;
	268	#ifdef CONFIG_IA32_EMULATION
	269	memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved,
	270	sizeof(struct _fpx_sw_bytes));
	271	fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size;
	272	#endif
	273	}
	274
dc1e35c6 SS	275	/*
	276	* Represents init state for the supported extended state.
	277	*/
	278	struct xsave_struct *init_xstate_buf;
	279
3c1c7f10 SS	280	#ifdef CONFIG_X86_64
	281	unsigned int sig_xstate_size = sizeof(struct _fpstate);
	282	#endif
	283
dc1e35c6 SS	284	/*
	285	* Enable the extended processor state save/restore feature
	286	*/
	287	void __cpuinit xsave_init(void)
	288	{
	289	if (!cpu_has_xsave)
	290	return;
	291
	292	set_in_cr4(X86_CR4_OSXSAVE);
	293
	294	/*
	295	* Enable all the features that the HW is capable of
	296	* and the Linux kernel is aware of.
dc1e35c6	297	*/
6152e4b1	298	xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask);
dc1e35c6 SS	299	}
	300
	301	/*
	302	* setup the xstate image representing the init state
	303	*/
a19aac85	304	static void __init setup_xstate_init(void)
dc1e35c6 SS	305	{
	306	init_xstate_buf = alloc_bootmem(xstate_size);
	307	init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;
	308	}
	309
	310	/*
	311	* Enable and initialize the xsave feature.
	312	*/
bfe085f6	313	void __ref xsave_cntxt_init(void)
dc1e35c6 SS	314	{
	315	unsigned int eax, ebx, ecx, edx;
	316
	317	cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx);
6152e4b1	318	pcntxt_mask = eax + ((u64)edx << 32);
dc1e35c6	319
6152e4b1 PA	320	if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) {
	321	printk(KERN_ERR "FP/SSE not shown under xsave features 0x%llx\n",
	322	pcntxt_mask);
dc1e35c6 SS	323	BUG();
	324	}
	325
	326	/*
	327	* for now OS knows only about FP/SSE
	328	*/
6152e4b1	329	pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
dc1e35c6 SS	330	xsave_init();
	331
	332	/*
	333	* Recompute the context size for enabled features
	334	*/
	335	cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx);
dc1e35c6 SS	336	xstate_size = ebx;
dc1e35c6 SS	337
c37b5efe SS	338	prepare_fx_sw_frame();
c37b5efe SS	339
dc1e35c6 SS	340	setup_xstate_init();
dc1e35c6 SS	341
6152e4b1	342	printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%llx, "
dc1e35c6	343	"cntxt size 0x%x\n",
6152e4b1	344	pcntxt_mask, xstate_size);
dc1e35c6	345	}