1/*
  2 * Based on arch/arm/kernel/signal.c
  3 *
  4 * Copyright (C) 1995-2009 Russell King
  5 * Copyright (C) 2012 ARM Ltd.
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 *
 11 * This program is distributed in the hope that it will be useful,
 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14 * GNU General Public License for more details.
 15 *
 16 * You should have received a copy of the GNU General Public License
 17 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 18 */
 19
 
 20#include <linux/compat.h>
 21#include <linux/errno.h>
 22#include <linux/kernel.h>
 23#include <linux/signal.h>
 24#include <linux/personality.h>
 25#include <linux/freezer.h>
 26#include <linux/stddef.h>
 27#include <linux/uaccess.h>
 28#include <linux/sizes.h>
 29#include <linux/string.h>
 30#include <linux/tracehook.h>
 31#include <linux/ratelimit.h>
 32#include <linux/syscalls.h>
 33
 34#include <asm/daifflags.h>
 35#include <asm/debug-monitors.h>
 36#include <asm/elf.h>
 
 37#include <asm/cacheflush.h>
 38#include <asm/ucontext.h>
 39#include <asm/unistd.h>
 40#include <asm/fpsimd.h>
 41#include <asm/ptrace.h>
 
 42#include <asm/signal32.h>
 43#include <asm/traps.h>
 44#include <asm/vdso.h>
 45
 46/*
 47 * Do a signal return; undo the signal stack. These are aligned to 128-bit.
 48 */
 49struct rt_sigframe {
 50	struct siginfo info;
 51	struct ucontext uc;
 52};
 53
 54struct frame_record {
 55	u64 fp;
 56	u64 lr;
 57};
 58
 59struct rt_sigframe_user_layout {
 60	struct rt_sigframe __user *sigframe;
 61	struct frame_record __user *next_frame;
 62
 63	unsigned long size;	/* size of allocated sigframe data */
 64	unsigned long limit;	/* largest allowed size */
 65
 66	unsigned long fpsimd_offset;
 67	unsigned long esr_offset;
 68	unsigned long sve_offset;
 
 
 
 69	unsigned long extra_offset;
 70	unsigned long end_offset;
 71};
 72
 73#define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
 74#define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
 75#define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
 76
 77static void init_user_layout(struct rt_sigframe_user_layout *user)
 78{
 79	const size_t reserved_size =
 80		sizeof(user->sigframe->uc.uc_mcontext.__reserved);
 81
 82	memset(user, 0, sizeof(*user));
 83	user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
 84
 85	user->limit = user->size + reserved_size;
 86
 87	user->limit -= TERMINATOR_SIZE;
 88	user->limit -= EXTRA_CONTEXT_SIZE;
 89	/* Reserve space for extension and terminator ^ */
 90}
 91
 92static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
 93{
 94	return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
 95}
 96
 97/*
 98 * Sanity limit on the approximate maximum size of signal frame we'll
 99 * try to generate.  Stack alignment padding and the frame record are
100 * not taken into account.  This limit is not a guarantee and is
101 * NOT ABI.
102 */
103#define SIGFRAME_MAXSZ SZ_64K
104
105static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
106			    unsigned long *offset, size_t size, bool extend)
107{
108	size_t padded_size = round_up(size, 16);
109
110	if (padded_size > user->limit - user->size &&
111	    !user->extra_offset &&
112	    extend) {
113		int ret;
114
115		user->limit += EXTRA_CONTEXT_SIZE;
116		ret = __sigframe_alloc(user, &user->extra_offset,
117				       sizeof(struct extra_context), false);
118		if (ret) {
119			user->limit -= EXTRA_CONTEXT_SIZE;
120			return ret;
121		}
122
123		/* Reserve space for the __reserved[] terminator */
124		user->size += TERMINATOR_SIZE;
125
126		/*
127		 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
128		 * the terminator:
129		 */
130		user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
131	}
132
133	/* Still not enough space?  Bad luck! */
134	if (padded_size > user->limit - user->size)
135		return -ENOMEM;
136
137	*offset = user->size;
138	user->size += padded_size;
139
140	return 0;
141}
142
143/*
144 * Allocate space for an optional record of <size> bytes in the user
145 * signal frame.  The offset from the signal frame base address to the
146 * allocated block is assigned to *offset.
147 */
148static int sigframe_alloc(struct rt_sigframe_user_layout *user,
149			  unsigned long *offset, size_t size)
150{
151	return __sigframe_alloc(user, offset, size, true);
152}
153
154/* Allocate the null terminator record and prevent further allocations */
155static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
156{
157	int ret;
158
159	/* Un-reserve the space reserved for the terminator: */
160	user->limit += TERMINATOR_SIZE;
161
162	ret = sigframe_alloc(user, &user->end_offset,
163			     sizeof(struct _aarch64_ctx));
164	if (ret)
165		return ret;
166
167	/* Prevent further allocation: */
168	user->limit = user->size;
169	return 0;
170}
171
172static void __user *apply_user_offset(
173	struct rt_sigframe_user_layout const *user, unsigned long offset)
174{
175	char __user *base = (char __user *)user->sigframe;
176
177	return base + offset;
178}
179
 
 
 
 
 
 
 
 
 
 
 
 
 
180static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
181{
182	struct user_fpsimd_state const *fpsimd =
183		&current->thread.uw.fpsimd_state;
184	int err;
185
186	/* copy the FP and status/control registers */
187	err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
188	__put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
189	__put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
190
191	/* copy the magic/size information */
192	__put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
193	__put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
194
195	return err ? -EFAULT : 0;
196}
197
198static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
199{
200	struct user_fpsimd_state fpsimd;
201	__u32 magic, size;
202	int err = 0;
203
204	/* check the magic/size information */
205	__get_user_error(magic, &ctx->head.magic, err);
206	__get_user_error(size, &ctx->head.size, err);
207	if (err)
208		return -EFAULT;
209	if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
210		return -EINVAL;
211
212	/* copy the FP and status/control registers */
213	err = __copy_from_user(fpsimd.vregs, ctx->vregs,
214			       sizeof(fpsimd.vregs));
215	__get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
216	__get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
217
218	clear_thread_flag(TIF_SVE);
 
219
220	/* load the hardware registers from the fpsimd_state structure */
221	if (!err)
222		fpsimd_update_current_state(&fpsimd);
223
224	return err ? -EFAULT : 0;
225}
226
227
228struct user_ctxs {
229	struct fpsimd_context __user *fpsimd;
230	struct sve_context __user *sve;
231};
232
233#ifdef CONFIG_ARM64_SVE
234
235static int preserve_sve_context(struct sve_context __user *ctx)
236{
237	int err = 0;
238	u16 reserved[ARRAY_SIZE(ctx->__reserved)];
239	unsigned int vl = current->thread.sve_vl;
 
240	unsigned int vq = 0;
241
242	if (test_thread_flag(TIF_SVE))
 
 
 
 
243		vq = sve_vq_from_vl(vl);
 
244
245	memset(reserved, 0, sizeof(reserved));
246
247	__put_user_error(SVE_MAGIC, &ctx->head.magic, err);
248	__put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
249			 &ctx->head.size, err);
250	__put_user_error(vl, &ctx->vl, err);
 
251	BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
252	err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
253
254	if (vq) {
255		/*
256		 * This assumes that the SVE state has already been saved to
257		 * the task struct by calling preserve_fpsimd_context().
 
258		 */
259		err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
260				      current->thread.sve_state,
261				      SVE_SIG_REGS_SIZE(vq));
262	}
263
264	return err ? -EFAULT : 0;
265}
266
267static int restore_sve_fpsimd_context(struct user_ctxs *user)
268{
269	int err;
270	unsigned int vq;
271	struct user_fpsimd_state fpsimd;
272	struct sve_context sve;
273
274	if (__copy_from_user(&sve, user->sve, sizeof(sve)))
275		return -EFAULT;
 
 
 
 
 
 
 
 
 
276
277	if (sve.vl != current->thread.sve_vl)
 
 
 
 
 
 
 
 
 
 
 
 
 
278		return -EINVAL;
279
280	if (sve.head.size <= sizeof(*user->sve)) {
281		clear_thread_flag(TIF_SVE);
 
 
282		goto fpsimd_only;
283	}
284
285	vq = sve_vq_from_vl(sve.vl);
286
287	if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
288		return -EINVAL;
289
290	/*
291	 * Careful: we are about __copy_from_user() directly into
292	 * thread.sve_state with preemption enabled, so protection is
293	 * needed to prevent a racing context switch from writing stale
294	 * registers back over the new data.
295	 */
296
297	fpsimd_flush_task_state(current);
298	barrier();
299	/* From now, fpsimd_thread_switch() won't clear TIF_FOREIGN_FPSTATE */
300
301	set_thread_flag(TIF_FOREIGN_FPSTATE);
302	barrier();
303	/* From now, fpsimd_thread_switch() won't touch thread.sve_state */
304
305	sve_alloc(current);
 
 
 
 
 
306	err = __copy_from_user(current->thread.sve_state,
307			       (char __user const *)user->sve +
308					SVE_SIG_REGS_OFFSET,
309			       SVE_SIG_REGS_SIZE(vq));
310	if (err)
311		return -EFAULT;
312
313	set_thread_flag(TIF_SVE);
 
 
 
 
314
315fpsimd_only:
316	/* copy the FP and status/control registers */
317	/* restore_sigframe() already checked that user->fpsimd != NULL. */
318	err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
319			       sizeof(fpsimd.vregs));
320	__get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
321	__get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
322
323	/* load the hardware registers from the fpsimd_state structure */
324	if (!err)
325		fpsimd_update_current_state(&fpsimd);
326
327	return err ? -EFAULT : 0;
328}
329
330#else /* ! CONFIG_ARM64_SVE */
331
332/* Turn any non-optimised out attempts to use these into a link error: */
 
 
 
 
 
 
333extern int preserve_sve_context(void __user *ctx);
334extern int restore_sve_fpsimd_context(struct user_ctxs *user);
335
336#endif /* ! CONFIG_ARM64_SVE */
337
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
338
339static int parse_user_sigframe(struct user_ctxs *user,
340			       struct rt_sigframe __user *sf)
341{
342	struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
343	struct _aarch64_ctx __user *head;
344	char __user *base = (char __user *)&sc->__reserved;
345	size_t offset = 0;
346	size_t limit = sizeof(sc->__reserved);
347	bool have_extra_context = false;
348	char const __user *const sfp = (char const __user *)sf;
349
350	user->fpsimd = NULL;
351	user->sve = NULL;
 
 
 
352
353	if (!IS_ALIGNED((unsigned long)base, 16))
354		goto invalid;
355
356	while (1) {
357		int err = 0;
358		u32 magic, size;
359		char const __user *userp;
360		struct extra_context const __user *extra;
361		u64 extra_datap;
362		u32 extra_size;
363		struct _aarch64_ctx const __user *end;
364		u32 end_magic, end_size;
365
366		if (limit - offset < sizeof(*head))
367			goto invalid;
368
369		if (!IS_ALIGNED(offset, 16))
370			goto invalid;
371
372		head = (struct _aarch64_ctx __user *)(base + offset);
373		__get_user_error(magic, &head->magic, err);
374		__get_user_error(size, &head->size, err);
375		if (err)
376			return err;
377
378		if (limit - offset < size)
379			goto invalid;
380
381		switch (magic) {
382		case 0:
383			if (size)
384				goto invalid;
385
386			goto done;
387
388		case FPSIMD_MAGIC:
389			if (user->fpsimd)
390				goto invalid;
391
392			if (size < sizeof(*user->fpsimd))
393				goto invalid;
394
395			user->fpsimd = (struct fpsimd_context __user *)head;
 
396			break;
397
398		case ESR_MAGIC:
399			/* ignore */
400			break;
401
402		case SVE_MAGIC:
403			if (!system_supports_sve())
404				goto invalid;
405
406			if (user->sve)
407				goto invalid;
408
409			if (size < sizeof(*user->sve))
 
 
 
 
 
410				goto invalid;
411
412			user->sve = (struct sve_context __user *)head;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
413			break;
414
415		case EXTRA_MAGIC:
416			if (have_extra_context)
417				goto invalid;
418
419			if (size < sizeof(*extra))
420				goto invalid;
421
422			userp = (char const __user *)head;
423
424			extra = (struct extra_context const __user *)userp;
425			userp += size;
426
427			__get_user_error(extra_datap, &extra->datap, err);
428			__get_user_error(extra_size, &extra->size, err);
429			if (err)
430				return err;
431
432			/* Check for the dummy terminator in __reserved[]: */
433
434			if (limit - offset - size < TERMINATOR_SIZE)
435				goto invalid;
436
437			end = (struct _aarch64_ctx const __user *)userp;
438			userp += TERMINATOR_SIZE;
439
440			__get_user_error(end_magic, &end->magic, err);
441			__get_user_error(end_size, &end->size, err);
442			if (err)
443				return err;
444
445			if (end_magic || end_size)
446				goto invalid;
447
448			/* Prevent looping/repeated parsing of extra_context */
449			have_extra_context = true;
450
451			base = (__force void __user *)extra_datap;
452			if (!IS_ALIGNED((unsigned long)base, 16))
453				goto invalid;
454
455			if (!IS_ALIGNED(extra_size, 16))
456				goto invalid;
457
458			if (base != userp)
459				goto invalid;
460
461			/* Reject "unreasonably large" frames: */
462			if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
463				goto invalid;
464
465			/*
466			 * Ignore trailing terminator in __reserved[]
467			 * and start parsing extra data:
468			 */
469			offset = 0;
470			limit = extra_size;
471
472			if (!access_ok(VERIFY_READ, base, limit))
473				goto invalid;
474
475			continue;
476
477		default:
478			goto invalid;
479		}
480
481		if (size < sizeof(*head))
482			goto invalid;
483
484		if (limit - offset < size)
485			goto invalid;
486
487		offset += size;
488	}
489
490done:
491	return 0;
492
493invalid:
494	return -EINVAL;
495}
496
497static int restore_sigframe(struct pt_regs *regs,
498			    struct rt_sigframe __user *sf)
499{
500	sigset_t set;
501	int i, err;
502	struct user_ctxs user;
503
504	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
505	if (err == 0)
506		set_current_blocked(&set);
507
508	for (i = 0; i < 31; i++)
509		__get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
510				 err);
511	__get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
512	__get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
513	__get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
514
515	/*
516	 * Avoid sys_rt_sigreturn() restarting.
517	 */
518	forget_syscall(regs);
519
520	err |= !valid_user_regs(&regs->user_regs, current);
521	if (err == 0)
522		err = parse_user_sigframe(&user, sf);
523
524	if (err == 0) {
525		if (!user.fpsimd)
526			return -EINVAL;
527
528		if (user.sve) {
529			if (!system_supports_sve())
530				return -EINVAL;
531
532			err = restore_sve_fpsimd_context(&user);
533		} else {
534			err = restore_fpsimd_context(user.fpsimd);
535		}
536	}
537
 
 
 
 
 
 
 
 
 
538	return err;
539}
540
541asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
542{
 
543	struct rt_sigframe __user *frame;
544
545	/* Always make any pending restarted system calls return -EINTR */
546	current->restart_block.fn = do_no_restart_syscall;
547
548	/*
549	 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
550	 * be word aligned here.
551	 */
552	if (regs->sp & 15)
553		goto badframe;
554
555	frame = (struct rt_sigframe __user *)regs->sp;
556
557	if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
558		goto badframe;
559
560	if (restore_sigframe(regs, frame))
561		goto badframe;
562
563	if (restore_altstack(&frame->uc.uc_stack))
564		goto badframe;
565
566	return regs->regs[0];
567
568badframe:
569	arm64_notify_segfault(regs->sp);
570	return 0;
571}
572
573/* Determine the layout of optional records in the signal frame */
574static int setup_sigframe_layout(struct rt_sigframe_user_layout *user)
 
 
 
 
 
 
 
575{
576	int err;
577
578	err = sigframe_alloc(user, &user->fpsimd_offset,
579			     sizeof(struct fpsimd_context));
580	if (err)
581		return err;
 
 
582
583	/* fault information, if valid */
584	if (current->thread.fault_code) {
585		err = sigframe_alloc(user, &user->esr_offset,
586				     sizeof(struct esr_context));
587		if (err)
588			return err;
589	}
590
591	if (system_supports_sve()) {
592		unsigned int vq = 0;
593
594		if (test_thread_flag(TIF_SVE))
595			vq = sve_vq_from_vl(current->thread.sve_vl);
 
 
 
 
 
 
 
596
597		err = sigframe_alloc(user, &user->sve_offset,
598				     SVE_SIG_CONTEXT_SIZE(vq));
599		if (err)
600			return err;
601	}
602
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
603	return sigframe_alloc_end(user);
604}
605
606
607static int setup_sigframe(struct rt_sigframe_user_layout *user,
608			  struct pt_regs *regs, sigset_t *set)
609{
610	int i, err = 0;
611	struct rt_sigframe __user *sf = user->sigframe;
612
613	/* set up the stack frame for unwinding */
614	__put_user_error(regs->regs[29], &user->next_frame->fp, err);
615	__put_user_error(regs->regs[30], &user->next_frame->lr, err);
616
617	for (i = 0; i < 31; i++)
618		__put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
619				 err);
620	__put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
621	__put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
622	__put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
623
624	__put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
625
626	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
627
628	if (err == 0) {
629		struct fpsimd_context __user *fpsimd_ctx =
630			apply_user_offset(user, user->fpsimd_offset);
631		err |= preserve_fpsimd_context(fpsimd_ctx);
632	}
633
634	/* fault information, if valid */
635	if (err == 0 && user->esr_offset) {
636		struct esr_context __user *esr_ctx =
637			apply_user_offset(user, user->esr_offset);
638
639		__put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
640		__put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
641		__put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
642	}
643
644	/* Scalable Vector Extension state, if present */
645	if (system_supports_sve() && err == 0 && user->sve_offset) {
 
646		struct sve_context __user *sve_ctx =
647			apply_user_offset(user, user->sve_offset);
648		err |= preserve_sve_context(sve_ctx);
649	}
650
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
651	if (err == 0 && user->extra_offset) {
652		char __user *sfp = (char __user *)user->sigframe;
653		char __user *userp =
654			apply_user_offset(user, user->extra_offset);
655
656		struct extra_context __user *extra;
657		struct _aarch64_ctx __user *end;
658		u64 extra_datap;
659		u32 extra_size;
660
661		extra = (struct extra_context __user *)userp;
662		userp += EXTRA_CONTEXT_SIZE;
663
664		end = (struct _aarch64_ctx __user *)userp;
665		userp += TERMINATOR_SIZE;
666
667		/*
668		 * extra_datap is just written to the signal frame.
669		 * The value gets cast back to a void __user *
670		 * during sigreturn.
671		 */
672		extra_datap = (__force u64)userp;
673		extra_size = sfp + round_up(user->size, 16) - userp;
674
675		__put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
676		__put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
677		__put_user_error(extra_datap, &extra->datap, err);
678		__put_user_error(extra_size, &extra->size, err);
679
680		/* Add the terminator */
681		__put_user_error(0, &end->magic, err);
682		__put_user_error(0, &end->size, err);
683	}
684
685	/* set the "end" magic */
686	if (err == 0) {
687		struct _aarch64_ctx __user *end =
688			apply_user_offset(user, user->end_offset);
689
690		__put_user_error(0, &end->magic, err);
691		__put_user_error(0, &end->size, err);
692	}
693
694	return err;
695}
696
697static int get_sigframe(struct rt_sigframe_user_layout *user,
698			 struct ksignal *ksig, struct pt_regs *regs)
699{
700	unsigned long sp, sp_top;
701	int err;
702
703	init_user_layout(user);
704	err = setup_sigframe_layout(user);
705	if (err)
706		return err;
707
708	sp = sp_top = sigsp(regs->sp, ksig);
709
710	sp = round_down(sp - sizeof(struct frame_record), 16);
711	user->next_frame = (struct frame_record __user *)sp;
712
713	sp = round_down(sp, 16) - sigframe_size(user);
714	user->sigframe = (struct rt_sigframe __user *)sp;
715
716	/*
717	 * Check that we can actually write to the signal frame.
718	 */
719	if (!access_ok(VERIFY_WRITE, user->sigframe, sp_top - sp))
720		return -EFAULT;
721
722	return 0;
723}
724
725static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
726			 struct rt_sigframe_user_layout *user, int usig)
727{
728	__sigrestore_t sigtramp;
729
730	regs->regs[0] = usig;
731	regs->sp = (unsigned long)user->sigframe;
732	regs->regs[29] = (unsigned long)&user->next_frame->fp;
733	regs->pc = (unsigned long)ka->sa.sa_handler;
734
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
735	if (ka->sa.sa_flags & SA_RESTORER)
736		sigtramp = ka->sa.sa_restorer;
737	else
738		sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
739
740	regs->regs[30] = (unsigned long)sigtramp;
741}
742
743static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
744			  struct pt_regs *regs)
745{
746	struct rt_sigframe_user_layout user;
747	struct rt_sigframe __user *frame;
748	int err = 0;
749
750	fpsimd_signal_preserve_current_state();
751
752	if (get_sigframe(&user, ksig, regs))
753		return 1;
754
755	frame = user.sigframe;
756
757	__put_user_error(0, &frame->uc.uc_flags, err);
758	__put_user_error(NULL, &frame->uc.uc_link, err);
759
760	err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
761	err |= setup_sigframe(&user, regs, set);
762	if (err == 0) {
763		setup_return(regs, &ksig->ka, &user, usig);
764		if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
765			err |= copy_siginfo_to_user(&frame->info, &ksig->info);
766			regs->regs[1] = (unsigned long)&frame->info;
767			regs->regs[2] = (unsigned long)&frame->uc;
768		}
769	}
770
771	return err;
772}
773
774static void setup_restart_syscall(struct pt_regs *regs)
775{
776	if (is_compat_task())
777		compat_setup_restart_syscall(regs);
778	else
779		regs->regs[8] = __NR_restart_syscall;
780}
781
782/*
783 * OK, we're invoking a handler
784 */
785static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
786{
787	struct task_struct *tsk = current;
788	sigset_t *oldset = sigmask_to_save();
789	int usig = ksig->sig;
790	int ret;
791
 
 
792	/*
793	 * Set up the stack frame
794	 */
795	if (is_compat_task()) {
796		if (ksig->ka.sa.sa_flags & SA_SIGINFO)
797			ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
798		else
799			ret = compat_setup_frame(usig, ksig, oldset, regs);
800	} else {
801		ret = setup_rt_frame(usig, ksig, oldset, regs);
802	}
803
804	/*
805	 * Check that the resulting registers are actually sane.
806	 */
807	ret |= !valid_user_regs(&regs->user_regs, current);
808
809	/*
810	 * Fast forward the stepping logic so we step into the signal
811	 * handler.
812	 */
813	if (!ret)
814		user_fastforward_single_step(tsk);
815
816	signal_setup_done(ret, ksig, 0);
817}
818
819/*
820 * Note that 'init' is a special process: it doesn't get signals it doesn't
821 * want to handle. Thus you cannot kill init even with a SIGKILL even by
822 * mistake.
823 *
824 * Note that we go through the signals twice: once to check the signals that
825 * the kernel can handle, and then we build all the user-level signal handling
826 * stack-frames in one go after that.
827 */
828static void do_signal(struct pt_regs *regs)
829{
830	unsigned long continue_addr = 0, restart_addr = 0;
831	int retval = 0;
832	struct ksignal ksig;
 
833
834	/*
835	 * If we were from a system call, check for system call restarting...
836	 */
837	if (in_syscall(regs)) {
838		continue_addr = regs->pc;
839		restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
840		retval = regs->regs[0];
841
842		/*
843		 * Avoid additional syscall restarting via ret_to_user.
844		 */
845		forget_syscall(regs);
846
847		/*
848		 * Prepare for system call restart. We do this here so that a
849		 * debugger will see the already changed PC.
850		 */
851		switch (retval) {
852		case -ERESTARTNOHAND:
853		case -ERESTARTSYS:
854		case -ERESTARTNOINTR:
855		case -ERESTART_RESTARTBLOCK:
856			regs->regs[0] = regs->orig_x0;
857			regs->pc = restart_addr;
858			break;
859		}
860	}
861
862	/*
863	 * Get the signal to deliver. When running under ptrace, at this point
864	 * the debugger may change all of our registers.
865	 */
866	if (get_signal(&ksig)) {
867		/*
868		 * Depending on the signal settings, we may need to revert the
869		 * decision to restart the system call, but skip this if a
870		 * debugger has chosen to restart at a different PC.
871		 */
872		if (regs->pc == restart_addr &&
873		    (retval == -ERESTARTNOHAND ||
874		     retval == -ERESTART_RESTARTBLOCK ||
875		     (retval == -ERESTARTSYS &&
876		      !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
877			regs->regs[0] = -EINTR;
878			regs->pc = continue_addr;
879		}
880
881		handle_signal(&ksig, regs);
882		return;
883	}
884
885	/*
886	 * Handle restarting a different system call. As above, if a debugger
887	 * has chosen to restart at a different PC, ignore the restart.
888	 */
889	if (in_syscall(regs) && regs->pc == restart_addr) {
890		if (retval == -ERESTART_RESTARTBLOCK)
891			setup_restart_syscall(regs);
892		user_rewind_single_step(current);
893	}
894
895	restore_saved_sigmask();
896}
897
898asmlinkage void do_notify_resume(struct pt_regs *regs,
899				 unsigned int thread_flags)
900{
901	/*
902	 * The assembly code enters us with IRQs off, but it hasn't
903	 * informed the tracing code of that for efficiency reasons.
904	 * Update the trace code with the current status.
905	 */
906	trace_hardirqs_off();
907
908	do {
909		/* Check valid user FS if needed */
910		addr_limit_user_check();
911
912		if (thread_flags & _TIF_NEED_RESCHED) {
913			/* Unmask Debug and SError for the next task */
914			local_daif_restore(DAIF_PROCCTX_NOIRQ);
915
916			schedule();
917		} else {
918			local_daif_restore(DAIF_PROCCTX);
919
920			if (thread_flags & _TIF_UPROBE)
921				uprobe_notify_resume(regs);
922
923			if (thread_flags & _TIF_SIGPENDING)
 
 
 
 
 
 
924				do_signal(regs);
925
926			if (thread_flags & _TIF_NOTIFY_RESUME) {
927				clear_thread_flag(TIF_NOTIFY_RESUME);
928				tracehook_notify_resume(regs);
929			}
930
931			if (thread_flags & _TIF_FOREIGN_FPSTATE)
932				fpsimd_restore_current_state();
933		}
934
935		local_daif_mask();
936		thread_flags = READ_ONCE(current_thread_info()->flags);
937	} while (thread_flags & _TIF_WORK_MASK);
938}