xref: /linux/arch/arm64/kernel/signal.c (revision 8c46def4)
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 
init_user_layout(struct rt_sigframe_user_layout * user)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 
sigframe_size(struct rt_sigframe_user_layout const * user)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 
__sigframe_alloc(struct rt_sigframe_user_layout * user,unsigned long * offset,size_t size,bool extend)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  */
sigframe_alloc(struct rt_sigframe_user_layout * user,unsigned long * offset,size_t size)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 */
sigframe_alloc_end(struct rt_sigframe_user_layout * user)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 
apply_user_offset(struct rt_sigframe_user_layout const * user,unsigned long offset)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 
preserve_fpsimd_context(struct fpsimd_context __user * ctx)190 static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
191 {
192 	struct user_fpsimd_state const *fpsimd =
193 		&current->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 
restore_fpsimd_context(struct user_ctxs * user)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 
preserve_fpmr_context(struct fpmr_context __user * ctx)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 
restore_fpmr_context(struct user_ctxs * user)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 
preserve_sve_context(struct sve_context __user * ctx)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(&current->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 
restore_sve_fpsimd_context(struct user_ctxs * user)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 
restore_sve_fpsimd_context(struct user_ctxs * user)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 
preserve_tpidr2_context(struct tpidr2_context __user * ctx)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 
restore_tpidr2_context(struct user_ctxs * user)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 
preserve_za_context(struct za_context __user * ctx)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(&current->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 
restore_za_context(struct user_ctxs * user)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 
preserve_zt_context(struct zt_context __user * ctx)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(&current->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(&current->thread),
552 			      ZT_SIG_REGS_SIZE(1));
553 
554 	return err ? -EFAULT : 0;
555 }
556 
restore_zt_context(struct user_ctxs * user)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(&current->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(&current->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 
parse_user_sigframe(struct user_ctxs * user,struct rt_sigframe __user * sf)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 
restore_sigframe(struct pt_regs * regs,struct rt_sigframe __user * sf)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(&regs->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 
SYSCALL_DEFINE0(rt_sigreturn)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  */
setup_sigframe_layout(struct rt_sigframe_user_layout * user,bool add_all)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(&current->thread)) {
928 			int vl = max(sve_max_vl(), sme_max_vl());
929 
930 			if (!add_all)
931 				vl = thread_get_cur_vl(&current->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(&current->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(&current->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 
setup_sigframe(struct rt_sigframe_user_layout * user,struct pt_regs * regs,sigset_t * set)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 
get_sigframe(struct rt_sigframe_user_layout * user,struct ksignal * ksig,struct pt_regs * regs)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 
setup_return(struct pt_regs * regs,struct k_sigaction * ka,struct rt_sigframe_user_layout * user,int usig)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(&current->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 
setup_rt_frame(int usig,struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)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 
setup_restart_syscall(struct pt_regs * regs)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  */
handle_signal(struct ksignal * ksig,struct pt_regs * regs)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(&regs->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  */
do_signal(struct pt_regs * regs)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  */
minsigstksz_setup(void)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