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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 = &current->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