1 /*
2 * xsave/xrstor support.
3 *
4 * Author: Suresh Siddha <suresh.b.siddha@intel.com>
5 */
6
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9 #include <linux/bootmem.h>
10 #include <linux/compat.h>
11 #include <linux/cpu.h>
12 #include <asm/i387.h>
13 #include <asm/fpu-internal.h>
14 #include <asm/sigframe.h>
15 #include <asm/tlbflush.h>
16 #include <asm/xcr.h>
17
18 /*
19 * Supported feature mask by the CPU and the kernel.
20 */
21 u64 pcntxt_mask;
22
23 /*
24 * Represents init state for the supported extended state.
25 */
26 struct xsave_struct *init_xstate_buf;
27
28 static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
29 static unsigned int *xstate_offsets, *xstate_sizes;
30 static unsigned int xstate_comp_offsets[sizeof(pcntxt_mask)*8];
31 static unsigned int xstate_features;
32
33 /*
34 * If a processor implementation discern that a processor state component is
35 * in its initialized state it may modify the corresponding bit in the
36 * xsave_hdr.xstate_bv as '0', with out modifying the corresponding memory
37 * layout in the case of xsaveopt. While presenting the xstate information to
38 * the user, we always ensure that the memory layout of a feature will be in
39 * the init state if the corresponding header bit is zero. This is to ensure
40 * that the user doesn't see some stale state in the memory layout during
41 * signal handling, debugging etc.
42 */
__sanitize_i387_state(struct task_struct * tsk)43 void __sanitize_i387_state(struct task_struct *tsk)
44 {
45 struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave;
46 int feature_bit = 0x2;
47 u64 xstate_bv;
48
49 if (!fx)
50 return;
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 up to 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
101 /*
102 * Check for the presence of extended state information in the
103 * user fpstate pointer in the sigcontext.
104 */
check_for_xstate(struct i387_fxsave_struct __user * buf,void __user * fpstate,struct _fpx_sw_bytes * fx_sw)105 static inline int check_for_xstate(struct i387_fxsave_struct __user *buf,
106 void __user *fpstate,
107 struct _fpx_sw_bytes *fx_sw)
108 {
109 int min_xstate_size = sizeof(struct i387_fxsave_struct) +
110 sizeof(struct xsave_hdr_struct);
111 unsigned int magic2;
112
113 if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
114 return -1;
115
116 /* Check for the first magic field and other error scenarios. */
117 if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
118 fx_sw->xstate_size < min_xstate_size ||
119 fx_sw->xstate_size > xstate_size ||
120 fx_sw->xstate_size > fx_sw->extended_size)
121 return -1;
122
123 /*
124 * Check for the presence of second magic word at the end of memory
125 * layout. This detects the case where the user just copied the legacy
126 * fpstate layout with out copying the extended state information
127 * in the memory layout.
128 */
129 if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
130 || magic2 != FP_XSTATE_MAGIC2)
131 return -1;
132
133 return 0;
134 }
135
136 /*
137 * Signal frame handlers.
138 */
save_fsave_header(struct task_struct * tsk,void __user * buf)139 static inline int save_fsave_header(struct task_struct *tsk, void __user *buf)
140 {
141 if (use_fxsr()) {
142 struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
143 struct user_i387_ia32_struct env;
144 struct _fpstate_ia32 __user *fp = buf;
145
146 convert_from_fxsr(&env, tsk);
147
148 if (__copy_to_user(buf, &env, sizeof(env)) ||
149 __put_user(xsave->i387.swd, &fp->status) ||
150 __put_user(X86_FXSR_MAGIC, &fp->magic))
151 return -1;
152 } else {
153 struct i387_fsave_struct __user *fp = buf;
154 u32 swd;
155 if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
156 return -1;
157 }
158
159 return 0;
160 }
161
save_xstate_epilog(void __user * buf,int ia32_frame)162 static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
163 {
164 struct xsave_struct __user *x = buf;
165 struct _fpx_sw_bytes *sw_bytes;
166 u32 xstate_bv;
167 int err;
168
169 /* Setup the bytes not touched by the [f]xsave and reserved for SW. */
170 sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved;
171 err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes));
172
173 if (!use_xsave())
174 return err;
175
176 err |= __put_user(FP_XSTATE_MAGIC2, (__u32 *)(buf + xstate_size));
177
178 /*
179 * Read the xstate_bv which we copied (directly from the cpu or
180 * from the state in task struct) to the user buffers.
181 */
182 err |= __get_user(xstate_bv, (__u32 *)&x->xsave_hdr.xstate_bv);
183
184 /*
185 * For legacy compatible, we always set FP/SSE bits in the bit
186 * vector while saving the state to the user context. This will
187 * enable us capturing any changes(during sigreturn) to
188 * the FP/SSE bits by the legacy applications which don't touch
189 * xstate_bv in the xsave header.
190 *
191 * xsave aware apps can change the xstate_bv in the xsave
192 * header as well as change any contents in the memory layout.
193 * xrestore as part of sigreturn will capture all the changes.
194 */
195 xstate_bv |= XSTATE_FPSSE;
196
197 err |= __put_user(xstate_bv, (__u32 *)&x->xsave_hdr.xstate_bv);
198
199 return err;
200 }
201
save_user_xstate(struct xsave_struct __user * buf)202 static inline int save_user_xstate(struct xsave_struct __user *buf)
203 {
204 int err;
205
206 if (use_xsave())
207 err = xsave_user(buf);
208 else if (use_fxsr())
209 err = fxsave_user((struct i387_fxsave_struct __user *) buf);
210 else
211 err = fsave_user((struct i387_fsave_struct __user *) buf);
212
213 if (unlikely(err) && __clear_user(buf, xstate_size))
214 err = -EFAULT;
215 return err;
216 }
217
218 /*
219 * Save the fpu, extended register state to the user signal frame.
220 *
221 * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
222 * state is copied.
223 * 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
224 *
225 * buf == buf_fx for 64-bit frames and 32-bit fsave frame.
226 * buf != buf_fx for 32-bit frames with fxstate.
227 *
228 * If the fpu, extended register state is live, save the state directly
229 * to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
230 * copy the thread's fpu state to the user frame starting at 'buf_fx'.
231 *
232 * If this is a 32-bit frame with fxstate, put a fsave header before
233 * the aligned state at 'buf_fx'.
234 *
235 * For [f]xsave state, update the SW reserved fields in the [f]xsave frame
236 * indicating the absence/presence of the extended state to the user.
237 */
save_xstate_sig(void __user * buf,void __user * buf_fx,int size)238 int save_xstate_sig(void __user *buf, void __user *buf_fx, int size)
239 {
240 struct xsave_struct *xsave = ¤t->thread.fpu.state->xsave;
241 struct task_struct *tsk = current;
242 int ia32_fxstate = (buf != buf_fx);
243
244 ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
245 config_enabled(CONFIG_IA32_EMULATION));
246
247 if (!access_ok(VERIFY_WRITE, buf, size))
248 return -EACCES;
249
250 if (!static_cpu_has(X86_FEATURE_FPU))
251 return fpregs_soft_get(current, NULL, 0,
252 sizeof(struct user_i387_ia32_struct), NULL,
253 (struct _fpstate_ia32 __user *) buf) ? -1 : 1;
254
255 if (user_has_fpu()) {
256 /* Save the live register state to the user directly. */
257 if (save_user_xstate(buf_fx))
258 return -1;
259 /* Update the thread's fxstate to save the fsave header. */
260 if (ia32_fxstate)
261 fpu_fxsave(&tsk->thread.fpu);
262 } else {
263 sanitize_i387_state(tsk);
264 if (__copy_to_user(buf_fx, xsave, xstate_size))
265 return -1;
266 }
267
268 /* Save the fsave header for the 32-bit frames. */
269 if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
270 return -1;
271
272 if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
273 return -1;
274
275 return 0;
276 }
277
278 static inline void
sanitize_restored_xstate(struct task_struct * tsk,struct user_i387_ia32_struct * ia32_env,u64 xstate_bv,int fx_only)279 sanitize_restored_xstate(struct task_struct *tsk,
280 struct user_i387_ia32_struct *ia32_env,
281 u64 xstate_bv, int fx_only)
282 {
283 struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
284 struct xsave_hdr_struct *xsave_hdr = &xsave->xsave_hdr;
285
286 if (use_xsave()) {
287 /* These bits must be zero. */
288 memset(xsave_hdr->reserved, 0, 48);
289
290 /*
291 * Init the state that is not present in the memory
292 * layout and not enabled by the OS.
293 */
294 if (fx_only)
295 xsave_hdr->xstate_bv = XSTATE_FPSSE;
296 else
297 xsave_hdr->xstate_bv &= (pcntxt_mask & xstate_bv);
298 }
299
300 if (use_fxsr()) {
301 /*
302 * mscsr reserved bits must be masked to zero for security
303 * reasons.
304 */
305 xsave->i387.mxcsr &= mxcsr_feature_mask;
306
307 convert_to_fxsr(tsk, ia32_env);
308 }
309 }
310
311 /*
312 * Restore the extended state if present. Otherwise, restore the FP/SSE state.
313 */
restore_user_xstate(void __user * buf,u64 xbv,int fx_only)314 static inline int restore_user_xstate(void __user *buf, u64 xbv, int fx_only)
315 {
316 if (use_xsave()) {
317 if ((unsigned long)buf % 64 || fx_only) {
318 u64 init_bv = pcntxt_mask & ~XSTATE_FPSSE;
319 xrstor_state(init_xstate_buf, init_bv);
320 return fxrstor_user(buf);
321 } else {
322 u64 init_bv = pcntxt_mask & ~xbv;
323 if (unlikely(init_bv))
324 xrstor_state(init_xstate_buf, init_bv);
325 return xrestore_user(buf, xbv);
326 }
327 } else if (use_fxsr()) {
328 return fxrstor_user(buf);
329 } else
330 return frstor_user(buf);
331 }
332
__restore_xstate_sig(void __user * buf,void __user * buf_fx,int size)333 int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
334 {
335 int ia32_fxstate = (buf != buf_fx);
336 struct task_struct *tsk = current;
337 int state_size = xstate_size;
338 u64 xstate_bv = 0;
339 int fx_only = 0;
340
341 ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
342 config_enabled(CONFIG_IA32_EMULATION));
343
344 if (!buf) {
345 drop_init_fpu(tsk);
346 return 0;
347 }
348
349 if (!access_ok(VERIFY_READ, buf, size))
350 return -EACCES;
351
352 if (!used_math() && init_fpu(tsk))
353 return -1;
354
355 if (!static_cpu_has(X86_FEATURE_FPU))
356 return fpregs_soft_set(current, NULL,
357 0, sizeof(struct user_i387_ia32_struct),
358 NULL, buf) != 0;
359
360 if (use_xsave()) {
361 struct _fpx_sw_bytes fx_sw_user;
362 if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
363 /*
364 * Couldn't find the extended state information in the
365 * memory layout. Restore just the FP/SSE and init all
366 * the other extended state.
367 */
368 state_size = sizeof(struct i387_fxsave_struct);
369 fx_only = 1;
370 } else {
371 state_size = fx_sw_user.xstate_size;
372 xstate_bv = fx_sw_user.xstate_bv;
373 }
374 }
375
376 if (ia32_fxstate) {
377 /*
378 * For 32-bit frames with fxstate, copy the user state to the
379 * thread's fpu state, reconstruct fxstate from the fsave
380 * header. Sanitize the copied state etc.
381 */
382 struct fpu *fpu = &tsk->thread.fpu;
383 struct user_i387_ia32_struct env;
384 int err = 0;
385
386 /*
387 * Drop the current fpu which clears used_math(). This ensures
388 * that any context-switch during the copy of the new state,
389 * avoids the intermediate state from getting restored/saved.
390 * Thus avoiding the new restored state from getting corrupted.
391 * We will be ready to restore/save the state only after
392 * set_used_math() is again set.
393 */
394 drop_fpu(tsk);
395
396 if (__copy_from_user(&fpu->state->xsave, buf_fx, state_size) ||
397 __copy_from_user(&env, buf, sizeof(env)) ||
398 (state_size > offsetof(struct xsave_struct, xsave_hdr) &&
399 fpu->state->xsave.xsave_hdr.xcomp_bv)) {
400 fpu_finit(fpu);
401 err = -1;
402 } else {
403 sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);
404 }
405
406 set_used_math();
407 if (use_eager_fpu()) {
408 preempt_disable();
409 math_state_restore();
410 preempt_enable();
411 }
412
413 return err;
414 } else {
415 /*
416 * For 64-bit frames and 32-bit fsave frames, restore the user
417 * state to the registers directly (with exceptions handled).
418 */
419 user_fpu_begin();
420 if (restore_user_xstate(buf_fx, xstate_bv, fx_only)) {
421 drop_init_fpu(tsk);
422 return -1;
423 }
424 }
425
426 return 0;
427 }
428
429 /*
430 * Prepare the SW reserved portion of the fxsave memory layout, indicating
431 * the presence of the extended state information in the memory layout
432 * pointed by the fpstate pointer in the sigcontext.
433 * This will be saved when ever the FP and extended state context is
434 * saved on the user stack during the signal handler delivery to the user.
435 */
prepare_fx_sw_frame(void)436 static void prepare_fx_sw_frame(void)
437 {
438 int fsave_header_size = sizeof(struct i387_fsave_struct);
439 int size = xstate_size + FP_XSTATE_MAGIC2_SIZE;
440
441 if (config_enabled(CONFIG_X86_32))
442 size += fsave_header_size;
443
444 fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
445 fx_sw_reserved.extended_size = size;
446 fx_sw_reserved.xstate_bv = pcntxt_mask;
447 fx_sw_reserved.xstate_size = xstate_size;
448
449 if (config_enabled(CONFIG_IA32_EMULATION)) {
450 fx_sw_reserved_ia32 = fx_sw_reserved;
451 fx_sw_reserved_ia32.extended_size += fsave_header_size;
452 }
453 }
454
455 /*
456 * Enable the extended processor state save/restore feature
457 */
xstate_enable(void)458 static inline void xstate_enable(void)
459 {
460 cr4_set_bits(X86_CR4_OSXSAVE);
461 xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask);
462 }
463
464 /*
465 * Record the offsets and sizes of different state managed by the xsave
466 * memory layout.
467 */
setup_xstate_features(void)468 static void __init setup_xstate_features(void)
469 {
470 int eax, ebx, ecx, edx, leaf = 0x2;
471
472 xstate_features = fls64(pcntxt_mask);
473 xstate_offsets = alloc_bootmem(xstate_features * sizeof(int));
474 xstate_sizes = alloc_bootmem(xstate_features * sizeof(int));
475
476 do {
477 cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx);
478
479 if (eax == 0)
480 break;
481
482 xstate_offsets[leaf] = ebx;
483 xstate_sizes[leaf] = eax;
484
485 leaf++;
486 } while (1);
487 }
488
489 /*
490 * This function sets up offsets and sizes of all extended states in
491 * xsave area. This supports both standard format and compacted format
492 * of the xsave aread.
493 *
494 * Input: void
495 * Output: void
496 */
setup_xstate_comp(void)497 void setup_xstate_comp(void)
498 {
499 unsigned int xstate_comp_sizes[sizeof(pcntxt_mask)*8];
500 int i;
501
502 /*
503 * The FP xstates and SSE xstates are legacy states. They are always
504 * in the fixed offsets in the xsave area in either compacted form
505 * or standard form.
506 */
507 xstate_comp_offsets[0] = 0;
508 xstate_comp_offsets[1] = offsetof(struct i387_fxsave_struct, xmm_space);
509
510 if (!cpu_has_xsaves) {
511 for (i = 2; i < xstate_features; i++) {
512 if (test_bit(i, (unsigned long *)&pcntxt_mask)) {
513 xstate_comp_offsets[i] = xstate_offsets[i];
514 xstate_comp_sizes[i] = xstate_sizes[i];
515 }
516 }
517 return;
518 }
519
520 xstate_comp_offsets[2] = FXSAVE_SIZE + XSAVE_HDR_SIZE;
521
522 for (i = 2; i < xstate_features; i++) {
523 if (test_bit(i, (unsigned long *)&pcntxt_mask))
524 xstate_comp_sizes[i] = xstate_sizes[i];
525 else
526 xstate_comp_sizes[i] = 0;
527
528 if (i > 2)
529 xstate_comp_offsets[i] = xstate_comp_offsets[i-1]
530 + xstate_comp_sizes[i-1];
531
532 }
533 }
534
535 /*
536 * setup the xstate image representing the init state
537 */
setup_init_fpu_buf(void)538 static void __init setup_init_fpu_buf(void)
539 {
540 /*
541 * Setup init_xstate_buf to represent the init state of
542 * all the features managed by the xsave
543 */
544 init_xstate_buf = alloc_bootmem_align(xstate_size,
545 __alignof__(struct xsave_struct));
546 fx_finit(&init_xstate_buf->i387);
547
548 if (!cpu_has_xsave)
549 return;
550
551 setup_xstate_features();
552
553 if (cpu_has_xsaves) {
554 init_xstate_buf->xsave_hdr.xcomp_bv =
555 (u64)1 << 63 | pcntxt_mask;
556 init_xstate_buf->xsave_hdr.xstate_bv = pcntxt_mask;
557 }
558
559 /*
560 * Init all the features state with header_bv being 0x0
561 */
562 xrstor_state_booting(init_xstate_buf, -1);
563 /*
564 * Dump the init state again. This is to identify the init state
565 * of any feature which is not represented by all zero's.
566 */
567 xsave_state_booting(init_xstate_buf, -1);
568 }
569
570 static enum { AUTO, ENABLE, DISABLE } eagerfpu = AUTO;
eager_fpu_setup(char * s)571 static int __init eager_fpu_setup(char *s)
572 {
573 if (!strcmp(s, "on"))
574 eagerfpu = ENABLE;
575 else if (!strcmp(s, "off"))
576 eagerfpu = DISABLE;
577 else if (!strcmp(s, "auto"))
578 eagerfpu = AUTO;
579 return 1;
580 }
581 __setup("eagerfpu=", eager_fpu_setup);
582
583
584 /*
585 * Calculate total size of enabled xstates in XCR0/pcntxt_mask.
586 */
init_xstate_size(void)587 static void __init init_xstate_size(void)
588 {
589 unsigned int eax, ebx, ecx, edx;
590 int i;
591
592 if (!cpu_has_xsaves) {
593 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
594 xstate_size = ebx;
595 return;
596 }
597
598 xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
599 for (i = 2; i < 64; i++) {
600 if (test_bit(i, (unsigned long *)&pcntxt_mask)) {
601 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
602 xstate_size += eax;
603 }
604 }
605 }
606
607 /*
608 * Enable and initialize the xsave feature.
609 */
xstate_enable_boot_cpu(void)610 static void __init xstate_enable_boot_cpu(void)
611 {
612 unsigned int eax, ebx, ecx, edx;
613
614 if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
615 WARN(1, KERN_ERR "XSTATE_CPUID missing\n");
616 return;
617 }
618
619 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
620 pcntxt_mask = eax + ((u64)edx << 32);
621
622 if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) {
623 pr_err("FP/SSE not shown under xsave features 0x%llx\n",
624 pcntxt_mask);
625 BUG();
626 }
627
628 /*
629 * Support only the state known to OS.
630 */
631 pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
632
633 xstate_enable();
634
635 /*
636 * Recompute the context size for enabled features
637 */
638 init_xstate_size();
639
640 update_regset_xstate_info(xstate_size, pcntxt_mask);
641 prepare_fx_sw_frame();
642 setup_init_fpu_buf();
643
644 /* Auto enable eagerfpu for xsaveopt */
645 if (cpu_has_xsaveopt && eagerfpu != DISABLE)
646 eagerfpu = ENABLE;
647
648 if (pcntxt_mask & XSTATE_EAGER) {
649 if (eagerfpu == DISABLE) {
650 pr_err("eagerfpu not present, disabling some xstate features: 0x%llx\n",
651 pcntxt_mask & XSTATE_EAGER);
652 pcntxt_mask &= ~XSTATE_EAGER;
653 } else {
654 eagerfpu = ENABLE;
655 }
656 }
657
658 pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x using %s\n",
659 pcntxt_mask, xstate_size,
660 cpu_has_xsaves ? "compacted form" : "standard form");
661 }
662
663 /*
664 * For the very first instance, this calls xstate_enable_boot_cpu();
665 * for all subsequent instances, this calls xstate_enable().
666 *
667 * This is somewhat obfuscated due to the lack of powerful enough
668 * overrides for the section checks.
669 */
xsave_init(void)670 void xsave_init(void)
671 {
672 static __refdata void (*next_func)(void) = xstate_enable_boot_cpu;
673 void (*this_func)(void);
674
675 if (!cpu_has_xsave)
676 return;
677
678 this_func = next_func;
679 next_func = xstate_enable;
680 this_func();
681 }
682
eager_fpu_init_bp(void)683 static inline void __init eager_fpu_init_bp(void)
684 {
685 current->thread.fpu.state =
686 alloc_bootmem_align(xstate_size, __alignof__(struct xsave_struct));
687 if (!init_xstate_buf)
688 setup_init_fpu_buf();
689 }
690
eager_fpu_init(void)691 void eager_fpu_init(void)
692 {
693 static __refdata void (*boot_func)(void) = eager_fpu_init_bp;
694
695 clear_used_math();
696 current_thread_info()->status = 0;
697
698 if (eagerfpu == ENABLE)
699 setup_force_cpu_cap(X86_FEATURE_EAGER_FPU);
700
701 if (!cpu_has_eager_fpu) {
702 stts();
703 return;
704 }
705
706 if (boot_func) {
707 boot_func();
708 boot_func = NULL;
709 }
710
711 /*
712 * This is same as math_state_restore(). But use_xsave() is
713 * not yet patched to use math_state_restore().
714 */
715 init_fpu(current);
716 __thread_fpu_begin(current);
717 if (cpu_has_xsave)
718 xrstor_state(init_xstate_buf, -1);
719 else
720 fxrstor_checking(&init_xstate_buf->i387);
721 }
722
723 /*
724 * Given the xsave area and a state inside, this function returns the
725 * address of the state.
726 *
727 * This is the API that is called to get xstate address in either
728 * standard format or compacted format of xsave area.
729 *
730 * Inputs:
731 * xsave: base address of the xsave area;
732 * xstate: state which is defined in xsave.h (e.g. XSTATE_FP, XSTATE_SSE,
733 * etc.)
734 * Output:
735 * address of the state in the xsave area.
736 */
get_xsave_addr(struct xsave_struct * xsave,int xstate)737 void *get_xsave_addr(struct xsave_struct *xsave, int xstate)
738 {
739 int feature = fls64(xstate) - 1;
740 if (!test_bit(feature, (unsigned long *)&pcntxt_mask))
741 return NULL;
742
743 return (void *)xsave + xstate_comp_offsets[feature];
744 }
745 EXPORT_SYMBOL_GPL(get_xsave_addr);
746