1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Based on arch/arm/kernel/signal.c
4 *
5 * Copyright (C) 1995-2009 Russell King
6 * Copyright (C) 2012 ARM Ltd.
7 */
8
9 #include <linux/cache.h>
10 #include <linux/compat.h>
11 #include <linux/errno.h>
12 #include <linux/kernel.h>
13 #include <linux/signal.h>
14 #include <linux/freezer.h>
15 #include <linux/stddef.h>
16 #include <linux/uaccess.h>
17 #include <linux/sizes.h>
18 #include <linux/string.h>
19 #include <linux/ratelimit.h>
20 #include <linux/rseq.h>
21 #include <linux/syscalls.h>
22
23 #include <asm/daifflags.h>
24 #include <asm/debug-monitors.h>
25 #include <asm/elf.h>
26 #include <asm/exception.h>
27 #include <asm/cacheflush.h>
28 #include <asm/ucontext.h>
29 #include <asm/unistd.h>
30 #include <asm/fpsimd.h>
31 #include <asm/ptrace.h>
32 #include <asm/syscall.h>
33 #include <asm/signal32.h>
34 #include <asm/traps.h>
35 #include <asm/vdso.h>
36
37 /*
38 * Do a signal return; undo the signal stack. These are aligned to 128-bit.
39 */
40 struct rt_sigframe {
41 struct siginfo info;
42 struct ucontext uc;
43 };
44
45 struct frame_record {
46 u64 fp;
47 u64 lr;
48 };
49
50 struct rt_sigframe_user_layout {
51 struct rt_sigframe __user *sigframe;
52 struct frame_record __user *next_frame;
53
54 unsigned long size; /* size of allocated sigframe data */
55 unsigned long limit; /* largest allowed size */
56
57 unsigned long fpsimd_offset;
58 unsigned long esr_offset;
59 unsigned long sve_offset;
60 unsigned long tpidr2_offset;
61 unsigned long za_offset;
62 unsigned long zt_offset;
63 unsigned long fpmr_offset;
64 unsigned long extra_offset;
65 unsigned long end_offset;
66 };
67
68 #define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
69 #define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
70 #define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
71
72 static void init_user_layout(struct rt_sigframe_user_layout *user)
73 {
74 const size_t reserved_size =
75 sizeof(user->sigframe->uc.uc_mcontext.__reserved);
76
77 memset(user, 0, sizeof(*user));
78 user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
79
80 user->limit = user->size + reserved_size;
81
82 user->limit -= TERMINATOR_SIZE;
83 user->limit -= EXTRA_CONTEXT_SIZE;
84 /* Reserve space for extension and terminator ^ */
85 }
86
87 static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
88 {
89 return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
90 }
91
92 /*
93 * Sanity limit on the approximate maximum size of signal frame we'll
94 * try to generate. Stack alignment padding and the frame record are
95 * not taken into account. This limit is not a guarantee and is
96 * NOT ABI.
97 */
98 #define SIGFRAME_MAXSZ SZ_256K
99
100 static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
101 unsigned long *offset, size_t size, bool extend)
102 {
103 size_t padded_size = round_up(size, 16);
104
105 if (padded_size > user->limit - user->size &&
106 !user->extra_offset &&
107 extend) {
108 int ret;
109
110 user->limit += EXTRA_CONTEXT_SIZE;
111 ret = __sigframe_alloc(user, &user->extra_offset,
112 sizeof(struct extra_context), false);
113 if (ret) {
114 user->limit -= EXTRA_CONTEXT_SIZE;
115 return ret;
116 }
117
118 /* Reserve space for the __reserved[] terminator */
119 user->size += TERMINATOR_SIZE;
120
121 /*
122 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
123 * the terminator:
124 */
125 user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
126 }
127
128 /* Still not enough space? Bad luck! */
129 if (padded_size > user->limit - user->size)
130 return -ENOMEM;
131
132 *offset = user->size;
133 user->size += padded_size;
134
135 return 0;
136 }
137
138 /*
139 * Allocate space for an optional record of <size> bytes in the user
140 * signal frame. The offset from the signal frame base address to the
141 * allocated block is assigned to *offset.
142 */
143 static int sigframe_alloc(struct rt_sigframe_user_layout *user,
144 unsigned long *offset, size_t size)
145 {
146 return __sigframe_alloc(user, offset, size, true);
147 }
148
149 /* Allocate the null terminator record and prevent further allocations */
150 static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
151 {
152 int ret;
153
154 /* Un-reserve the space reserved for the terminator: */
155 user->limit += TERMINATOR_SIZE;
156
157 ret = sigframe_alloc(user, &user->end_offset,
158 sizeof(struct _aarch64_ctx));
159 if (ret)
160 return ret;
161
162 /* Prevent further allocation: */
163 user->limit = user->size;
164 return 0;
165 }
166
167 static void __user *apply_user_offset(
168 struct rt_sigframe_user_layout const *user, unsigned long offset)
169 {
170 char __user *base = (char __user *)user->sigframe;
171
172 return base + offset;
173 }
174
175 struct user_ctxs {
176 struct fpsimd_context __user *fpsimd;
177 u32 fpsimd_size;
178 struct sve_context __user *sve;
179 u32 sve_size;
180 struct tpidr2_context __user *tpidr2;
181 u32 tpidr2_size;
182 struct za_context __user *za;
183 u32 za_size;
184 struct zt_context __user *zt;
185 u32 zt_size;
186 struct fpmr_context __user *fpmr;
187 u32 fpmr_size;
188 };
189
190 static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
191 {
192 struct user_fpsimd_state const *fpsimd =
193 ¤t->thread.uw.fpsimd_state;
194 int err;
195
196 /* copy the FP and status/control registers */
197 err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
198 __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
199 __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
200
201 /* copy the magic/size information */
202 __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
203 __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
204
205 return err ? -EFAULT : 0;
206 }
207
208 static int restore_fpsimd_context(struct user_ctxs *user)
209 {
210 struct user_fpsimd_state fpsimd;
211 int err = 0;
212
213 /* check the size information */
214 if (user->fpsimd_size != sizeof(struct fpsimd_context))
215 return -EINVAL;
216
217 /* copy the FP and status/control registers */
218 err = __copy_from_user(fpsimd.vregs, &(user->fpsimd->vregs),
219 sizeof(fpsimd.vregs));
220 __get_user_error(fpsimd.fpsr, &(user->fpsimd->fpsr), err);
221 __get_user_error(fpsimd.fpcr, &(user->fpsimd->fpcr), err);
222
223 clear_thread_flag(TIF_SVE);
224 current->thread.fp_type = FP_STATE_FPSIMD;
225
226 /* load the hardware registers from the fpsimd_state structure */
227 if (!err)
228 fpsimd_update_current_state(&fpsimd);
229
230 return err ? -EFAULT : 0;
231 }
232
233 static int preserve_fpmr_context(struct fpmr_context __user *ctx)
234 {
235 int err = 0;
236
237 current->thread.uw.fpmr = read_sysreg_s(SYS_FPMR);
238
239 __put_user_error(FPMR_MAGIC, &ctx->head.magic, err);
240 __put_user_error(sizeof(*ctx), &ctx->head.size, err);
241 __put_user_error(current->thread.uw.fpmr, &ctx->fpmr, err);
242
243 return err;
244 }
245
246 static int restore_fpmr_context(struct user_ctxs *user)
247 {
248 u64 fpmr;
249 int err = 0;
250
251 if (user->fpmr_size != sizeof(*user->fpmr))
252 return -EINVAL;
253
254 __get_user_error(fpmr, &user->fpmr->fpmr, err);
255 if (!err)
256 write_sysreg_s(fpmr, SYS_FPMR);
257
258 return err;
259 }
260
261 #ifdef CONFIG_ARM64_SVE
262
263 static int preserve_sve_context(struct sve_context __user *ctx)
264 {
265 int err = 0;
266 u16 reserved[ARRAY_SIZE(ctx->__reserved)];
267 u16 flags = 0;
268 unsigned int vl = task_get_sve_vl(current);
269 unsigned int vq = 0;
270
271 if (thread_sm_enabled(¤t->thread)) {
272 vl = task_get_sme_vl(current);
273 vq = sve_vq_from_vl(vl);
274 flags |= SVE_SIG_FLAG_SM;
275 } else if (current->thread.fp_type == FP_STATE_SVE) {
276 vq = sve_vq_from_vl(vl);
277 }
278
279 memset(reserved, 0, sizeof(reserved));
280
281 __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
282 __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
283 &ctx->head.size, err);
284 __put_user_error(vl, &ctx->vl, err);
285 __put_user_error(flags, &ctx->flags, err);
286 BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
287 err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
288
289 if (vq) {
290 /*
291 * This assumes that the SVE state has already been saved to
292 * the task struct by calling the function
293 * fpsimd_signal_preserve_current_state().
294 */
295 err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
296 current->thread.sve_state,
297 SVE_SIG_REGS_SIZE(vq));
298 }
299
300 return err ? -EFAULT : 0;
301 }
302
303 static int restore_sve_fpsimd_context(struct user_ctxs *user)
304 {
305 int err = 0;
306 unsigned int vl, vq;
307 struct user_fpsimd_state fpsimd;
308 u16 user_vl, flags;
309
310 if (user->sve_size < sizeof(*user->sve))
311 return -EINVAL;
312
313 __get_user_error(user_vl, &(user->sve->vl), err);
314 __get_user_error(flags, &(user->sve->flags), err);
315 if (err)
316 return err;
317
318 if (flags & SVE_SIG_FLAG_SM) {
319 if (!system_supports_sme())
320 return -EINVAL;
321
322 vl = task_get_sme_vl(current);
323 } else {
324 /*
325 * A SME only system use SVE for streaming mode so can
326 * have a SVE formatted context with a zero VL and no
327 * payload data.
328 */
329 if (!system_supports_sve() && !system_supports_sme())
330 return -EINVAL;
331
332 vl = task_get_sve_vl(current);
333 }
334
335 if (user_vl != vl)
336 return -EINVAL;
337
338 if (user->sve_size == sizeof(*user->sve)) {
339 clear_thread_flag(TIF_SVE);
340 current->thread.svcr &= ~SVCR_SM_MASK;
341 current->thread.fp_type = FP_STATE_FPSIMD;
342 goto fpsimd_only;
343 }
344
345 vq = sve_vq_from_vl(vl);
346
347 if (user->sve_size < SVE_SIG_CONTEXT_SIZE(vq))
348 return -EINVAL;
349
350 /*
351 * Careful: we are about __copy_from_user() directly into
352 * thread.sve_state with preemption enabled, so protection is
353 * needed to prevent a racing context switch from writing stale
354 * registers back over the new data.
355 */
356
357 fpsimd_flush_task_state(current);
358 /* From now, fpsimd_thread_switch() won't touch thread.sve_state */
359
360 sve_alloc(current, true);
361 if (!current->thread.sve_state) {
362 clear_thread_flag(TIF_SVE);
363 return -ENOMEM;
364 }
365
366 err = __copy_from_user(current->thread.sve_state,
367 (char __user const *)user->sve +
368 SVE_SIG_REGS_OFFSET,
369 SVE_SIG_REGS_SIZE(vq));
370 if (err)
371 return -EFAULT;
372
373 if (flags & SVE_SIG_FLAG_SM)
374 current->thread.svcr |= SVCR_SM_MASK;
375 else
376 set_thread_flag(TIF_SVE);
377 current->thread.fp_type = FP_STATE_SVE;
378
379 fpsimd_only:
380 /* copy the FP and status/control registers */
381 /* restore_sigframe() already checked that user->fpsimd != NULL. */
382 err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
383 sizeof(fpsimd.vregs));
384 __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
385 __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
386
387 /* load the hardware registers from the fpsimd_state structure */
388 if (!err)
389 fpsimd_update_current_state(&fpsimd);
390
391 return err ? -EFAULT : 0;
392 }
393
394 #else /* ! CONFIG_ARM64_SVE */
395
396 static int restore_sve_fpsimd_context(struct user_ctxs *user)
397 {
398 WARN_ON_ONCE(1);
399 return -EINVAL;
400 }
401
402 /* Turn any non-optimised out attempts to use this into a link error: */
403 extern int preserve_sve_context(void __user *ctx);
404
405 #endif /* ! CONFIG_ARM64_SVE */
406
407 #ifdef CONFIG_ARM64_SME
408
409 static int preserve_tpidr2_context(struct tpidr2_context __user *ctx)
410 {
411 int err = 0;
412
413 current->thread.tpidr2_el0 = read_sysreg_s(SYS_TPIDR2_EL0);
414
415 __put_user_error(TPIDR2_MAGIC, &ctx->head.magic, err);
416 __put_user_error(sizeof(*ctx), &ctx->head.size, err);
417 __put_user_error(current->thread.tpidr2_el0, &ctx->tpidr2, err);
418
419 return err;
420 }
421
422 static int restore_tpidr2_context(struct user_ctxs *user)
423 {
424 u64 tpidr2_el0;
425 int err = 0;
426
427 if (user->tpidr2_size != sizeof(*user->tpidr2))
428 return -EINVAL;
429
430 __get_user_error(tpidr2_el0, &user->tpidr2->tpidr2, err);
431 if (!err)
432 write_sysreg_s(tpidr2_el0, SYS_TPIDR2_EL0);
433
434 return err;
435 }
436
437 static int preserve_za_context(struct za_context __user *ctx)
438 {
439 int err = 0;
440 u16 reserved[ARRAY_SIZE(ctx->__reserved)];
441 unsigned int vl = task_get_sme_vl(current);
442 unsigned int vq;
443
444 if (thread_za_enabled(¤t->thread))
445 vq = sve_vq_from_vl(vl);
446 else
447 vq = 0;
448
449 memset(reserved, 0, sizeof(reserved));
450
451 __put_user_error(ZA_MAGIC, &ctx->head.magic, err);
452 __put_user_error(round_up(ZA_SIG_CONTEXT_SIZE(vq), 16),
453 &ctx->head.size, err);
454 __put_user_error(vl, &ctx->vl, err);
455 BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
456 err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
457
458 if (vq) {
459 /*
460 * This assumes that the ZA state has already been saved to
461 * the task struct by calling the function
462 * fpsimd_signal_preserve_current_state().
463 */
464 err |= __copy_to_user((char __user *)ctx + ZA_SIG_REGS_OFFSET,
465 current->thread.sme_state,
466 ZA_SIG_REGS_SIZE(vq));
467 }
468
469 return err ? -EFAULT : 0;
470 }
471
472 static int restore_za_context(struct user_ctxs *user)
473 {
474 int err = 0;
475 unsigned int vq;
476 u16 user_vl;
477
478 if (user->za_size < sizeof(*user->za))
479 return -EINVAL;
480
481 __get_user_error(user_vl, &(user->za->vl), err);
482 if (err)
483 return err;
484
485 if (user_vl != task_get_sme_vl(current))
486 return -EINVAL;
487
488 if (user->za_size == sizeof(*user->za)) {
489 current->thread.svcr &= ~SVCR_ZA_MASK;
490 return 0;
491 }
492
493 vq = sve_vq_from_vl(user_vl);
494
495 if (user->za_size < ZA_SIG_CONTEXT_SIZE(vq))
496 return -EINVAL;
497
498 /*
499 * Careful: we are about __copy_from_user() directly into
500 * thread.sme_state with preemption enabled, so protection is
501 * needed to prevent a racing context switch from writing stale
502 * registers back over the new data.
503 */
504
505 fpsimd_flush_task_state(current);
506 /* From now, fpsimd_thread_switch() won't touch thread.sve_state */
507
508 sme_alloc(current, true);
509 if (!current->thread.sme_state) {
510 current->thread.svcr &= ~SVCR_ZA_MASK;
511 clear_thread_flag(TIF_SME);
512 return -ENOMEM;
513 }
514
515 err = __copy_from_user(current->thread.sme_state,
516 (char __user const *)user->za +
517 ZA_SIG_REGS_OFFSET,
518 ZA_SIG_REGS_SIZE(vq));
519 if (err)
520 return -EFAULT;
521
522 set_thread_flag(TIF_SME);
523 current->thread.svcr |= SVCR_ZA_MASK;
524
525 return 0;
526 }
527
528 static int preserve_zt_context(struct zt_context __user *ctx)
529 {
530 int err = 0;
531 u16 reserved[ARRAY_SIZE(ctx->__reserved)];
532
533 if (WARN_ON(!thread_za_enabled(¤t->thread)))
534 return -EINVAL;
535
536 memset(reserved, 0, sizeof(reserved));
537
538 __put_user_error(ZT_MAGIC, &ctx->head.magic, err);
539 __put_user_error(round_up(ZT_SIG_CONTEXT_SIZE(1), 16),
540 &ctx->head.size, err);
541 __put_user_error(1, &ctx->nregs, err);
542 BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
543 err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
544
545 /*
546 * This assumes that the ZT state has already been saved to
547 * the task struct by calling the function
548 * fpsimd_signal_preserve_current_state().
549 */
550 err |= __copy_to_user((char __user *)ctx + ZT_SIG_REGS_OFFSET,
551 thread_zt_state(¤t->thread),
552 ZT_SIG_REGS_SIZE(1));
553
554 return err ? -EFAULT : 0;
555 }
556
557 static int restore_zt_context(struct user_ctxs *user)
558 {
559 int err;
560 u16 nregs;
561
562 /* ZA must be restored first for this check to be valid */
563 if (!thread_za_enabled(¤t->thread))
564 return -EINVAL;
565
566 if (user->zt_size != ZT_SIG_CONTEXT_SIZE(1))
567 return -EINVAL;
568
569 if (__copy_from_user(&nregs, &(user->zt->nregs), sizeof(nregs)))
570 return -EFAULT;
571
572 if (nregs != 1)
573 return -EINVAL;
574
575 /*
576 * Careful: we are about __copy_from_user() directly into
577 * thread.zt_state with preemption enabled, so protection is
578 * needed to prevent a racing context switch from writing stale
579 * registers back over the new data.
580 */
581
582 fpsimd_flush_task_state(current);
583 /* From now, fpsimd_thread_switch() won't touch ZT in thread state */
584
585 err = __copy_from_user(thread_zt_state(¤t->thread),
586 (char __user const *)user->zt +
587 ZT_SIG_REGS_OFFSET,
588 ZT_SIG_REGS_SIZE(1));
589 if (err)
590 return -EFAULT;
591
592 return 0;
593 }
594
595 #else /* ! CONFIG_ARM64_SME */
596
597 /* Turn any non-optimised out attempts to use these into a link error: */
598 extern int preserve_tpidr2_context(void __user *ctx);
599 extern int restore_tpidr2_context(struct user_ctxs *user);
600 extern int preserve_za_context(void __user *ctx);
601 extern int restore_za_context(struct user_ctxs *user);
602 extern int preserve_zt_context(void __user *ctx);
603 extern int restore_zt_context(struct user_ctxs *user);
604
605 #endif /* ! CONFIG_ARM64_SME */
606
607 static int parse_user_sigframe(struct user_ctxs *user,
608 struct rt_sigframe __user *sf)
609 {
610 struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
611 struct _aarch64_ctx __user *head;
612 char __user *base = (char __user *)&sc->__reserved;
613 size_t offset = 0;
614 size_t limit = sizeof(sc->__reserved);
615 bool have_extra_context = false;
616 char const __user *const sfp = (char const __user *)sf;
617
618 user->fpsimd = NULL;
619 user->sve = NULL;
620 user->tpidr2 = NULL;
621 user->za = NULL;
622 user->zt = NULL;
623 user->fpmr = NULL;
624
625 if (!IS_ALIGNED((unsigned long)base, 16))
626 goto invalid;
627
628 while (1) {
629 int err = 0;
630 u32 magic, size;
631 char const __user *userp;
632 struct extra_context const __user *extra;
633 u64 extra_datap;
634 u32 extra_size;
635 struct _aarch64_ctx const __user *end;
636 u32 end_magic, end_size;
637
638 if (limit - offset < sizeof(*head))
639 goto invalid;
640
641 if (!IS_ALIGNED(offset, 16))
642 goto invalid;
643
644 head = (struct _aarch64_ctx __user *)(base + offset);
645 __get_user_error(magic, &head->magic, err);
646 __get_user_error(size, &head->size, err);
647 if (err)
648 return err;
649
650 if (limit - offset < size)
651 goto invalid;
652
653 switch (magic) {
654 case 0:
655 if (size)
656 goto invalid;
657
658 goto done;
659
660 case FPSIMD_MAGIC:
661 if (!system_supports_fpsimd())
662 goto invalid;
663 if (user->fpsimd)
664 goto invalid;
665
666 user->fpsimd = (struct fpsimd_context __user *)head;
667 user->fpsimd_size = size;
668 break;
669
670 case ESR_MAGIC:
671 /* ignore */
672 break;
673
674 case SVE_MAGIC:
675 if (!system_supports_sve() && !system_supports_sme())
676 goto invalid;
677
678 if (user->sve)
679 goto invalid;
680
681 user->sve = (struct sve_context __user *)head;
682 user->sve_size = size;
683 break;
684
685 case TPIDR2_MAGIC:
686 if (!system_supports_tpidr2())
687 goto invalid;
688
689 if (user->tpidr2)
690 goto invalid;
691
692 user->tpidr2 = (struct tpidr2_context __user *)head;
693 user->tpidr2_size = size;
694 break;
695
696 case ZA_MAGIC:
697 if (!system_supports_sme())
698 goto invalid;
699
700 if (user->za)
701 goto invalid;
702
703 user->za = (struct za_context __user *)head;
704 user->za_size = size;
705 break;
706
707 case ZT_MAGIC:
708 if (!system_supports_sme2())
709 goto invalid;
710
711 if (user->zt)
712 goto invalid;
713
714 user->zt = (struct zt_context __user *)head;
715 user->zt_size = size;
716 break;
717
718 case FPMR_MAGIC:
719 if (!system_supports_fpmr())
720 goto invalid;
721
722 if (user->fpmr)
723 goto invalid;
724
725 user->fpmr = (struct fpmr_context __user *)head;
726 user->fpmr_size = size;
727 break;
728
729 case EXTRA_MAGIC:
730 if (have_extra_context)
731 goto invalid;
732
733 if (size < sizeof(*extra))
734 goto invalid;
735
736 userp = (char const __user *)head;
737
738 extra = (struct extra_context const __user *)userp;
739 userp += size;
740
741 __get_user_error(extra_datap, &extra->datap, err);
742 __get_user_error(extra_size, &extra->size, err);
743 if (err)
744 return err;
745
746 /* Check for the dummy terminator in __reserved[]: */
747
748 if (limit - offset - size < TERMINATOR_SIZE)
749 goto invalid;
750
751 end = (struct _aarch64_ctx const __user *)userp;
752 userp += TERMINATOR_SIZE;
753
754 __get_user_error(end_magic, &end->magic, err);
755 __get_user_error(end_size, &end->size, err);
756 if (err)
757 return err;
758
759 if (end_magic || end_size)
760 goto invalid;
761
762 /* Prevent looping/repeated parsing of extra_context */
763 have_extra_context = true;
764
765 base = (__force void __user *)extra_datap;
766 if (!IS_ALIGNED((unsigned long)base, 16))
767 goto invalid;
768
769 if (!IS_ALIGNED(extra_size, 16))
770 goto invalid;
771
772 if (base != userp)
773 goto invalid;
774
775 /* Reject "unreasonably large" frames: */
776 if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
777 goto invalid;
778
779 /*
780 * Ignore trailing terminator in __reserved[]
781 * and start parsing extra data:
782 */
783 offset = 0;
784 limit = extra_size;
785
786 if (!access_ok(base, limit))
787 goto invalid;
788
789 continue;
790
791 default:
792 goto invalid;
793 }
794
795 if (size < sizeof(*head))
796 goto invalid;
797
798 if (limit - offset < size)
799 goto invalid;
800
801 offset += size;
802 }
803
804 done:
805 return 0;
806
807 invalid:
808 return -EINVAL;
809 }
810
811 static int restore_sigframe(struct pt_regs *regs,
812 struct rt_sigframe __user *sf)
813 {
814 sigset_t set;
815 int i, err;
816 struct user_ctxs user;
817
818 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
819 if (err == 0)
820 set_current_blocked(&set);
821
822 for (i = 0; i < 31; i++)
823 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
824 err);
825 __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
826 __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
827 __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
828
829 /*
830 * Avoid sys_rt_sigreturn() restarting.
831 */
832 forget_syscall(regs);
833
834 err |= !valid_user_regs(®s->user_regs, current);
835 if (err == 0)
836 err = parse_user_sigframe(&user, sf);
837
838 if (err == 0 && system_supports_fpsimd()) {
839 if (!user.fpsimd)
840 return -EINVAL;
841
842 if (user.sve)
843 err = restore_sve_fpsimd_context(&user);
844 else
845 err = restore_fpsimd_context(&user);
846 }
847
848 if (err == 0 && system_supports_tpidr2() && user.tpidr2)
849 err = restore_tpidr2_context(&user);
850
851 if (err == 0 && system_supports_fpmr() && user.fpmr)
852 err = restore_fpmr_context(&user);
853
854 if (err == 0 && system_supports_sme() && user.za)
855 err = restore_za_context(&user);
856
857 if (err == 0 && system_supports_sme2() && user.zt)
858 err = restore_zt_context(&user);
859
860 return err;
861 }
862
863 SYSCALL_DEFINE0(rt_sigreturn)
864 {
865 struct pt_regs *regs = current_pt_regs();
866 struct rt_sigframe __user *frame;
867
868 /* Always make any pending restarted system calls return -EINTR */
869 current->restart_block.fn = do_no_restart_syscall;
870
871 /*
872 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
873 * be word aligned here.
874 */
875 if (regs->sp & 15)
876 goto badframe;
877
878 frame = (struct rt_sigframe __user *)regs->sp;
879
880 if (!access_ok(frame, sizeof (*frame)))
881 goto badframe;
882
883 if (restore_sigframe(regs, frame))
884 goto badframe;
885
886 if (restore_altstack(&frame->uc.uc_stack))
887 goto badframe;
888
889 return regs->regs[0];
890
891 badframe:
892 arm64_notify_segfault(regs->sp);
893 return 0;
894 }
895
896 /*
897 * Determine the layout of optional records in the signal frame
898 *
899 * add_all: if true, lays out the biggest possible signal frame for
900 * this task; otherwise, generates a layout for the current state
901 * of the task.
902 */
903 static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
904 bool add_all)
905 {
906 int err;
907
908 if (system_supports_fpsimd()) {
909 err = sigframe_alloc(user, &user->fpsimd_offset,
910 sizeof(struct fpsimd_context));
911 if (err)
912 return err;
913 }
914
915 /* fault information, if valid */
916 if (add_all || current->thread.fault_code) {
917 err = sigframe_alloc(user, &user->esr_offset,
918 sizeof(struct esr_context));
919 if (err)
920 return err;
921 }
922
923 if (system_supports_sve() || system_supports_sme()) {
924 unsigned int vq = 0;
925
926 if (add_all || current->thread.fp_type == FP_STATE_SVE ||
927 thread_sm_enabled(¤t->thread)) {
928 int vl = max(sve_max_vl(), sme_max_vl());
929
930 if (!add_all)
931 vl = thread_get_cur_vl(¤t->thread);
932
933 vq = sve_vq_from_vl(vl);
934 }
935
936 err = sigframe_alloc(user, &user->sve_offset,
937 SVE_SIG_CONTEXT_SIZE(vq));
938 if (err)
939 return err;
940 }
941
942 if (system_supports_tpidr2()) {
943 err = sigframe_alloc(user, &user->tpidr2_offset,
944 sizeof(struct tpidr2_context));
945 if (err)
946 return err;
947 }
948
949 if (system_supports_sme()) {
950 unsigned int vl;
951 unsigned int vq = 0;
952
953 if (add_all)
954 vl = sme_max_vl();
955 else
956 vl = task_get_sme_vl(current);
957
958 if (thread_za_enabled(¤t->thread))
959 vq = sve_vq_from_vl(vl);
960
961 err = sigframe_alloc(user, &user->za_offset,
962 ZA_SIG_CONTEXT_SIZE(vq));
963 if (err)
964 return err;
965 }
966
967 if (system_supports_sme2()) {
968 if (add_all || thread_za_enabled(¤t->thread)) {
969 err = sigframe_alloc(user, &user->zt_offset,
970 ZT_SIG_CONTEXT_SIZE(1));
971 if (err)
972 return err;
973 }
974 }
975
976 if (system_supports_fpmr()) {
977 err = sigframe_alloc(user, &user->fpmr_offset,
978 sizeof(struct fpmr_context));
979 if (err)
980 return err;
981 }
982
983 return sigframe_alloc_end(user);
984 }
985
986 static int setup_sigframe(struct rt_sigframe_user_layout *user,
987 struct pt_regs *regs, sigset_t *set)
988 {
989 int i, err = 0;
990 struct rt_sigframe __user *sf = user->sigframe;
991
992 /* set up the stack frame for unwinding */
993 __put_user_error(regs->regs[29], &user->next_frame->fp, err);
994 __put_user_error(regs->regs[30], &user->next_frame->lr, err);
995
996 for (i = 0; i < 31; i++)
997 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
998 err);
999 __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
1000 __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
1001 __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
1002
1003 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
1004
1005 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
1006
1007 if (err == 0 && system_supports_fpsimd()) {
1008 struct fpsimd_context __user *fpsimd_ctx =
1009 apply_user_offset(user, user->fpsimd_offset);
1010 err |= preserve_fpsimd_context(fpsimd_ctx);
1011 }
1012
1013 /* fault information, if valid */
1014 if (err == 0 && user->esr_offset) {
1015 struct esr_context __user *esr_ctx =
1016 apply_user_offset(user, user->esr_offset);
1017
1018 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
1019 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
1020 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
1021 }
1022
1023 /* Scalable Vector Extension state (including streaming), if present */
1024 if ((system_supports_sve() || system_supports_sme()) &&
1025 err == 0 && user->sve_offset) {
1026 struct sve_context __user *sve_ctx =
1027 apply_user_offset(user, user->sve_offset);
1028 err |= preserve_sve_context(sve_ctx);
1029 }
1030
1031 /* TPIDR2 if supported */
1032 if (system_supports_tpidr2() && err == 0) {
1033 struct tpidr2_context __user *tpidr2_ctx =
1034 apply_user_offset(user, user->tpidr2_offset);
1035 err |= preserve_tpidr2_context(tpidr2_ctx);
1036 }
1037
1038 /* FPMR if supported */
1039 if (system_supports_fpmr() && err == 0) {
1040 struct fpmr_context __user *fpmr_ctx =
1041 apply_user_offset(user, user->fpmr_offset);
1042 err |= preserve_fpmr_context(fpmr_ctx);
1043 }
1044
1045 /* ZA state if present */
1046 if (system_supports_sme() && err == 0 && user->za_offset) {
1047 struct za_context __user *za_ctx =
1048 apply_user_offset(user, user->za_offset);
1049 err |= preserve_za_context(za_ctx);
1050 }
1051
1052 /* ZT state if present */
1053 if (system_supports_sme2() && err == 0 && user->zt_offset) {
1054 struct zt_context __user *zt_ctx =
1055 apply_user_offset(user, user->zt_offset);
1056 err |= preserve_zt_context(zt_ctx);
1057 }
1058
1059 if (err == 0 && user->extra_offset) {
1060 char __user *sfp = (char __user *)user->sigframe;
1061 char __user *userp =
1062 apply_user_offset(user, user->extra_offset);
1063
1064 struct extra_context __user *extra;
1065 struct _aarch64_ctx __user *end;
1066 u64 extra_datap;
1067 u32 extra_size;
1068
1069 extra = (struct extra_context __user *)userp;
1070 userp += EXTRA_CONTEXT_SIZE;
1071
1072 end = (struct _aarch64_ctx __user *)userp;
1073 userp += TERMINATOR_SIZE;
1074
1075 /*
1076 * extra_datap is just written to the signal frame.
1077 * The value gets cast back to a void __user *
1078 * during sigreturn.
1079 */
1080 extra_datap = (__force u64)userp;
1081 extra_size = sfp + round_up(user->size, 16) - userp;
1082
1083 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
1084 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
1085 __put_user_error(extra_datap, &extra->datap, err);
1086 __put_user_error(extra_size, &extra->size, err);
1087
1088 /* Add the terminator */
1089 __put_user_error(0, &end->magic, err);
1090 __put_user_error(0, &end->size, err);
1091 }
1092
1093 /* set the "end" magic */
1094 if (err == 0) {
1095 struct _aarch64_ctx __user *end =
1096 apply_user_offset(user, user->end_offset);
1097
1098 __put_user_error(0, &end->magic, err);
1099 __put_user_error(0, &end->size, err);
1100 }
1101
1102 return err;
1103 }
1104
1105 static int get_sigframe(struct rt_sigframe_user_layout *user,
1106 struct ksignal *ksig, struct pt_regs *regs)
1107 {
1108 unsigned long sp, sp_top;
1109 int err;
1110
1111 init_user_layout(user);
1112 err = setup_sigframe_layout(user, false);
1113 if (err)
1114 return err;
1115
1116 sp = sp_top = sigsp(regs->sp, ksig);
1117
1118 sp = round_down(sp - sizeof(struct frame_record), 16);
1119 user->next_frame = (struct frame_record __user *)sp;
1120
1121 sp = round_down(sp, 16) - sigframe_size(user);
1122 user->sigframe = (struct rt_sigframe __user *)sp;
1123
1124 /*
1125 * Check that we can actually write to the signal frame.
1126 */
1127 if (!access_ok(user->sigframe, sp_top - sp))
1128 return -EFAULT;
1129
1130 return 0;
1131 }
1132
1133 static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
1134 struct rt_sigframe_user_layout *user, int usig)
1135 {
1136 __sigrestore_t sigtramp;
1137
1138 regs->regs[0] = usig;
1139 regs->sp = (unsigned long)user->sigframe;
1140 regs->regs[29] = (unsigned long)&user->next_frame->fp;
1141 regs->pc = (unsigned long)ka->sa.sa_handler;
1142
1143 /*
1144 * Signal delivery is a (wacky) indirect function call in
1145 * userspace, so simulate the same setting of BTYPE as a BLR
1146 * <register containing the signal handler entry point>.
1147 * Signal delivery to a location in a PROT_BTI guarded page
1148 * that is not a function entry point will now trigger a
1149 * SIGILL in userspace.
1150 *
1151 * If the signal handler entry point is not in a PROT_BTI
1152 * guarded page, this is harmless.
1153 */
1154 if (system_supports_bti()) {
1155 regs->pstate &= ~PSR_BTYPE_MASK;
1156 regs->pstate |= PSR_BTYPE_C;
1157 }
1158
1159 /* TCO (Tag Check Override) always cleared for signal handlers */
1160 regs->pstate &= ~PSR_TCO_BIT;
1161
1162 /* Signal handlers are invoked with ZA and streaming mode disabled */
1163 if (system_supports_sme()) {
1164 /*
1165 * If we were in streaming mode the saved register
1166 * state was SVE but we will exit SM and use the
1167 * FPSIMD register state - flush the saved FPSIMD
1168 * register state in case it gets loaded.
1169 */
1170 if (current->thread.svcr & SVCR_SM_MASK) {
1171 memset(¤t->thread.uw.fpsimd_state, 0,
1172 sizeof(current->thread.uw.fpsimd_state));
1173 current->thread.fp_type = FP_STATE_FPSIMD;
1174 }
1175
1176 current->thread.svcr &= ~(SVCR_ZA_MASK |
1177 SVCR_SM_MASK);
1178 sme_smstop();
1179 }
1180
1181 if (ka->sa.sa_flags & SA_RESTORER)
1182 sigtramp = ka->sa.sa_restorer;
1183 else
1184 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
1185
1186 regs->regs[30] = (unsigned long)sigtramp;
1187 }
1188
1189 static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
1190 struct pt_regs *regs)
1191 {
1192 struct rt_sigframe_user_layout user;
1193 struct rt_sigframe __user *frame;
1194 int err = 0;
1195
1196 fpsimd_signal_preserve_current_state();
1197
1198 if (get_sigframe(&user, ksig, regs))
1199 return 1;
1200
1201 frame = user.sigframe;
1202
1203 __put_user_error(0, &frame->uc.uc_flags, err);
1204 __put_user_error(NULL, &frame->uc.uc_link, err);
1205
1206 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
1207 err |= setup_sigframe(&user, regs, set);
1208 if (err == 0) {
1209 setup_return(regs, &ksig->ka, &user, usig);
1210 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
1211 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
1212 regs->regs[1] = (unsigned long)&frame->info;
1213 regs->regs[2] = (unsigned long)&frame->uc;
1214 }
1215 }
1216
1217 return err;
1218 }
1219
1220 static void setup_restart_syscall(struct pt_regs *regs)
1221 {
1222 if (is_compat_task())
1223 compat_setup_restart_syscall(regs);
1224 else
1225 regs->regs[8] = __NR_restart_syscall;
1226 }
1227
1228 /*
1229 * OK, we're invoking a handler
1230 */
1231 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
1232 {
1233 sigset_t *oldset = sigmask_to_save();
1234 int usig = ksig->sig;
1235 int ret;
1236
1237 rseq_signal_deliver(ksig, regs);
1238
1239 /*
1240 * Set up the stack frame
1241 */
1242 if (is_compat_task()) {
1243 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
1244 ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
1245 else
1246 ret = compat_setup_frame(usig, ksig, oldset, regs);
1247 } else {
1248 ret = setup_rt_frame(usig, ksig, oldset, regs);
1249 }
1250
1251 /*
1252 * Check that the resulting registers are actually sane.
1253 */
1254 ret |= !valid_user_regs(®s->user_regs, current);
1255
1256 /* Step into the signal handler if we are stepping */
1257 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
1258 }
1259
1260 /*
1261 * Note that 'init' is a special process: it doesn't get signals it doesn't
1262 * want to handle. Thus you cannot kill init even with a SIGKILL even by
1263 * mistake.
1264 *
1265 * Note that we go through the signals twice: once to check the signals that
1266 * the kernel can handle, and then we build all the user-level signal handling
1267 * stack-frames in one go after that.
1268 */
1269 void do_signal(struct pt_regs *regs)
1270 {
1271 unsigned long continue_addr = 0, restart_addr = 0;
1272 int retval = 0;
1273 struct ksignal ksig;
1274 bool syscall = in_syscall(regs);
1275
1276 /*
1277 * If we were from a system call, check for system call restarting...
1278 */
1279 if (syscall) {
1280 continue_addr = regs->pc;
1281 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
1282 retval = regs->regs[0];
1283
1284 /*
1285 * Avoid additional syscall restarting via ret_to_user.
1286 */
1287 forget_syscall(regs);
1288
1289 /*
1290 * Prepare for system call restart. We do this here so that a
1291 * debugger will see the already changed PC.
1292 */
1293 switch (retval) {
1294 case -ERESTARTNOHAND:
1295 case -ERESTARTSYS:
1296 case -ERESTARTNOINTR:
1297 case -ERESTART_RESTARTBLOCK:
1298 regs->regs[0] = regs->orig_x0;
1299 regs->pc = restart_addr;
1300 break;
1301 }
1302 }
1303
1304 /*
1305 * Get the signal to deliver. When running under ptrace, at this point
1306 * the debugger may change all of our registers.
1307 */
1308 if (get_signal(&ksig)) {
1309 /*
1310 * Depending on the signal settings, we may need to revert the
1311 * decision to restart the system call, but skip this if a
1312 * debugger has chosen to restart at a different PC.
1313 */
1314 if (regs->pc == restart_addr &&
1315 (retval == -ERESTARTNOHAND ||
1316 retval == -ERESTART_RESTARTBLOCK ||
1317 (retval == -ERESTARTSYS &&
1318 !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
1319 syscall_set_return_value(current, regs, -EINTR, 0);
1320 regs->pc = continue_addr;
1321 }
1322
1323 handle_signal(&ksig, regs);
1324 return;
1325 }
1326
1327 /*
1328 * Handle restarting a different system call. As above, if a debugger
1329 * has chosen to restart at a different PC, ignore the restart.
1330 */
1331 if (syscall && regs->pc == restart_addr) {
1332 if (retval == -ERESTART_RESTARTBLOCK)
1333 setup_restart_syscall(regs);
1334 user_rewind_single_step(current);
1335 }
1336
1337 restore_saved_sigmask();
1338 }
1339
1340 unsigned long __ro_after_init signal_minsigstksz;
1341
1342 /*
1343 * Determine the stack space required for guaranteed signal devliery.
1344 * This function is used to populate AT_MINSIGSTKSZ at process startup.
1345 * cpufeatures setup is assumed to be complete.
1346 */
1347 void __init minsigstksz_setup(void)
1348 {
1349 struct rt_sigframe_user_layout user;
1350
1351 init_user_layout(&user);
1352
1353 /*
1354 * If this fails, SIGFRAME_MAXSZ needs to be enlarged. It won't
1355 * be big enough, but it's our best guess:
1356 */
1357 if (WARN_ON(setup_sigframe_layout(&user, true)))
1358 return;
1359
1360 signal_minsigstksz = sigframe_size(&user) +
1361 round_up(sizeof(struct frame_record), 16) +
1362 16; /* max alignment padding */
1363 }
1364
1365 /*
1366 * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
1367 * changes likely come with new fields that should be added below.
1368 */
1369 static_assert(NSIGILL == 11);
1370 static_assert(NSIGFPE == 15);
1371 static_assert(NSIGSEGV == 10);
1372 static_assert(NSIGBUS == 5);
1373 static_assert(NSIGTRAP == 6);
1374 static_assert(NSIGCHLD == 6);
1375 static_assert(NSIGSYS == 2);
1376 static_assert(sizeof(siginfo_t) == 128);
1377 static_assert(__alignof__(siginfo_t) == 8);
1378 static_assert(offsetof(siginfo_t, si_signo) == 0x00);
1379 static_assert(offsetof(siginfo_t, si_errno) == 0x04);
1380 static_assert(offsetof(siginfo_t, si_code) == 0x08);
1381 static_assert(offsetof(siginfo_t, si_pid) == 0x10);
1382 static_assert(offsetof(siginfo_t, si_uid) == 0x14);
1383 static_assert(offsetof(siginfo_t, si_tid) == 0x10);
1384 static_assert(offsetof(siginfo_t, si_overrun) == 0x14);
1385 static_assert(offsetof(siginfo_t, si_status) == 0x18);
1386 static_assert(offsetof(siginfo_t, si_utime) == 0x20);
1387 static_assert(offsetof(siginfo_t, si_stime) == 0x28);
1388 static_assert(offsetof(siginfo_t, si_value) == 0x18);
1389 static_assert(offsetof(siginfo_t, si_int) == 0x18);
1390 static_assert(offsetof(siginfo_t, si_ptr) == 0x18);
1391 static_assert(offsetof(siginfo_t, si_addr) == 0x10);
1392 static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x18);
1393 static_assert(offsetof(siginfo_t, si_lower) == 0x20);
1394 static_assert(offsetof(siginfo_t, si_upper) == 0x28);
1395 static_assert(offsetof(siginfo_t, si_pkey) == 0x20);
1396 static_assert(offsetof(siginfo_t, si_perf_data) == 0x18);
1397 static_assert(offsetof(siginfo_t, si_perf_type) == 0x20);
1398 static_assert(offsetof(siginfo_t, si_perf_flags) == 0x24);
1399 static_assert(offsetof(siginfo_t, si_band) == 0x10);
1400 static_assert(offsetof(siginfo_t, si_fd) == 0x18);
1401 static_assert(offsetof(siginfo_t, si_call_addr) == 0x10);
1402 static_assert(offsetof(siginfo_t, si_syscall) == 0x18);
1403 static_assert(offsetof(siginfo_t, si_arch) == 0x1c);
1404
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