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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/arm/kernel/signal.c
4 *
5 * Copyright (C) 1995-2009 Russell King
6 */
7#include <linux/errno.h>
8#include <linux/random.h>
9#include <linux/signal.h>
10#include <linux/personality.h>
11#include <linux/uaccess.h>
12#include <linux/tracehook.h>
13#include <linux/uprobes.h>
14#include <linux/syscalls.h>
15
16#include <asm/elf.h>
17#include <asm/cacheflush.h>
18#include <asm/traps.h>
19#include <asm/unistd.h>
20#include <asm/vfp.h>
21
22#include "signal.h"
23
24extern const unsigned long sigreturn_codes[17];
25
26static unsigned long signal_return_offset;
27
28#ifdef CONFIG_CRUNCH
29static int preserve_crunch_context(struct crunch_sigframe __user *frame)
30{
31 char kbuf[sizeof(*frame) + 8];
32 struct crunch_sigframe *kframe;
33
34 /* the crunch context must be 64 bit aligned */
35 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
36 kframe->magic = CRUNCH_MAGIC;
37 kframe->size = CRUNCH_STORAGE_SIZE;
38 crunch_task_copy(current_thread_info(), &kframe->storage);
39 return __copy_to_user(frame, kframe, sizeof(*frame));
40}
41
42static int restore_crunch_context(char __user **auxp)
43{
44 struct crunch_sigframe __user *frame =
45 (struct crunch_sigframe __user *)*auxp;
46 char kbuf[sizeof(*frame) + 8];
47 struct crunch_sigframe *kframe;
48
49 /* the crunch context must be 64 bit aligned */
50 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
51 if (__copy_from_user(kframe, frame, sizeof(*frame)))
52 return -1;
53 if (kframe->magic != CRUNCH_MAGIC ||
54 kframe->size != CRUNCH_STORAGE_SIZE)
55 return -1;
56 *auxp += CRUNCH_STORAGE_SIZE;
57 crunch_task_restore(current_thread_info(), &kframe->storage);
58 return 0;
59}
60#endif
61
62#ifdef CONFIG_IWMMXT
63
64static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame)
65{
66 char kbuf[sizeof(*frame) + 8];
67 struct iwmmxt_sigframe *kframe;
68 int err = 0;
69
70 /* the iWMMXt context must be 64 bit aligned */
71 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
72
73 if (test_thread_flag(TIF_USING_IWMMXT)) {
74 kframe->magic = IWMMXT_MAGIC;
75 kframe->size = IWMMXT_STORAGE_SIZE;
76 iwmmxt_task_copy(current_thread_info(), &kframe->storage);
77 } else {
78 /*
79 * For bug-compatibility with older kernels, some space
80 * has to be reserved for iWMMXt even if it's not used.
81 * Set the magic and size appropriately so that properly
82 * written userspace can skip it reliably:
83 */
84 *kframe = (struct iwmmxt_sigframe) {
85 .magic = DUMMY_MAGIC,
86 .size = IWMMXT_STORAGE_SIZE,
87 };
88 }
89
90 err = __copy_to_user(frame, kframe, sizeof(*kframe));
91
92 return err;
93}
94
95static int restore_iwmmxt_context(char __user **auxp)
96{
97 struct iwmmxt_sigframe __user *frame =
98 (struct iwmmxt_sigframe __user *)*auxp;
99 char kbuf[sizeof(*frame) + 8];
100 struct iwmmxt_sigframe *kframe;
101
102 /* the iWMMXt context must be 64 bit aligned */
103 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
104 if (__copy_from_user(kframe, frame, sizeof(*frame)))
105 return -1;
106
107 /*
108 * For non-iWMMXt threads: a single iwmmxt_sigframe-sized dummy
109 * block is discarded for compatibility with setup_sigframe() if
110 * present, but we don't mandate its presence. If some other
111 * magic is here, it's not for us:
112 */
113 if (!test_thread_flag(TIF_USING_IWMMXT) &&
114 kframe->magic != DUMMY_MAGIC)
115 return 0;
116
117 if (kframe->size != IWMMXT_STORAGE_SIZE)
118 return -1;
119
120 if (test_thread_flag(TIF_USING_IWMMXT)) {
121 if (kframe->magic != IWMMXT_MAGIC)
122 return -1;
123
124 iwmmxt_task_restore(current_thread_info(), &kframe->storage);
125 }
126
127 *auxp += IWMMXT_STORAGE_SIZE;
128 return 0;
129}
130
131#endif
132
133#ifdef CONFIG_VFP
134
135static int preserve_vfp_context(struct vfp_sigframe __user *frame)
136{
137 struct vfp_sigframe kframe;
138 int err = 0;
139
140 memset(&kframe, 0, sizeof(kframe));
141 kframe.magic = VFP_MAGIC;
142 kframe.size = VFP_STORAGE_SIZE;
143
144 err = vfp_preserve_user_clear_hwstate(&kframe.ufp, &kframe.ufp_exc);
145 if (err)
146 return err;
147
148 return __copy_to_user(frame, &kframe, sizeof(kframe));
149}
150
151static int restore_vfp_context(char __user **auxp)
152{
153 struct vfp_sigframe frame;
154 int err;
155
156 err = __copy_from_user(&frame, *auxp, sizeof(frame));
157 if (err)
158 return err;
159
160 if (frame.magic != VFP_MAGIC || frame.size != VFP_STORAGE_SIZE)
161 return -EINVAL;
162
163 *auxp += sizeof(frame);
164 return vfp_restore_user_hwstate(&frame.ufp, &frame.ufp_exc);
165}
166
167#endif
168
169/*
170 * Do a signal return; undo the signal stack. These are aligned to 64-bit.
171 */
172
173static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
174{
175 struct sigcontext context;
176 char __user *aux;
177 sigset_t set;
178 int err;
179
180 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
181 if (err == 0)
182 set_current_blocked(&set);
183
184 err |= __copy_from_user(&context, &sf->uc.uc_mcontext, sizeof(context));
185 if (err == 0) {
186 regs->ARM_r0 = context.arm_r0;
187 regs->ARM_r1 = context.arm_r1;
188 regs->ARM_r2 = context.arm_r2;
189 regs->ARM_r3 = context.arm_r3;
190 regs->ARM_r4 = context.arm_r4;
191 regs->ARM_r5 = context.arm_r5;
192 regs->ARM_r6 = context.arm_r6;
193 regs->ARM_r7 = context.arm_r7;
194 regs->ARM_r8 = context.arm_r8;
195 regs->ARM_r9 = context.arm_r9;
196 regs->ARM_r10 = context.arm_r10;
197 regs->ARM_fp = context.arm_fp;
198 regs->ARM_ip = context.arm_ip;
199 regs->ARM_sp = context.arm_sp;
200 regs->ARM_lr = context.arm_lr;
201 regs->ARM_pc = context.arm_pc;
202 regs->ARM_cpsr = context.arm_cpsr;
203 }
204
205 err |= !valid_user_regs(regs);
206
207 aux = (char __user *) sf->uc.uc_regspace;
208#ifdef CONFIG_CRUNCH
209 if (err == 0)
210 err |= restore_crunch_context(&aux);
211#endif
212#ifdef CONFIG_IWMMXT
213 if (err == 0)
214 err |= restore_iwmmxt_context(&aux);
215#endif
216#ifdef CONFIG_VFP
217 if (err == 0)
218 err |= restore_vfp_context(&aux);
219#endif
220
221 return err;
222}
223
224asmlinkage int sys_sigreturn(struct pt_regs *regs)
225{
226 struct sigframe __user *frame;
227
228 /* Always make any pending restarted system calls return -EINTR */
229 current->restart_block.fn = do_no_restart_syscall;
230
231 /*
232 * Since we stacked the signal on a 64-bit boundary,
233 * then 'sp' should be word aligned here. If it's
234 * not, then the user is trying to mess with us.
235 */
236 if (regs->ARM_sp & 7)
237 goto badframe;
238
239 frame = (struct sigframe __user *)regs->ARM_sp;
240
241 if (!access_ok(frame, sizeof (*frame)))
242 goto badframe;
243
244 if (restore_sigframe(regs, frame))
245 goto badframe;
246
247 return regs->ARM_r0;
248
249badframe:
250 force_sig(SIGSEGV);
251 return 0;
252}
253
254asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
255{
256 struct rt_sigframe __user *frame;
257
258 /* Always make any pending restarted system calls return -EINTR */
259 current->restart_block.fn = do_no_restart_syscall;
260
261 /*
262 * Since we stacked the signal on a 64-bit boundary,
263 * then 'sp' should be word aligned here. If it's
264 * not, then the user is trying to mess with us.
265 */
266 if (regs->ARM_sp & 7)
267 goto badframe;
268
269 frame = (struct rt_sigframe __user *)regs->ARM_sp;
270
271 if (!access_ok(frame, sizeof (*frame)))
272 goto badframe;
273
274 if (restore_sigframe(regs, &frame->sig))
275 goto badframe;
276
277 if (restore_altstack(&frame->sig.uc.uc_stack))
278 goto badframe;
279
280 return regs->ARM_r0;
281
282badframe:
283 force_sig(SIGSEGV);
284 return 0;
285}
286
287static int
288setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
289{
290 struct aux_sigframe __user *aux;
291 struct sigcontext context;
292 int err = 0;
293
294 context = (struct sigcontext) {
295 .arm_r0 = regs->ARM_r0,
296 .arm_r1 = regs->ARM_r1,
297 .arm_r2 = regs->ARM_r2,
298 .arm_r3 = regs->ARM_r3,
299 .arm_r4 = regs->ARM_r4,
300 .arm_r5 = regs->ARM_r5,
301 .arm_r6 = regs->ARM_r6,
302 .arm_r7 = regs->ARM_r7,
303 .arm_r8 = regs->ARM_r8,
304 .arm_r9 = regs->ARM_r9,
305 .arm_r10 = regs->ARM_r10,
306 .arm_fp = regs->ARM_fp,
307 .arm_ip = regs->ARM_ip,
308 .arm_sp = regs->ARM_sp,
309 .arm_lr = regs->ARM_lr,
310 .arm_pc = regs->ARM_pc,
311 .arm_cpsr = regs->ARM_cpsr,
312
313 .trap_no = current->thread.trap_no,
314 .error_code = current->thread.error_code,
315 .fault_address = current->thread.address,
316 .oldmask = set->sig[0],
317 };
318
319 err |= __copy_to_user(&sf->uc.uc_mcontext, &context, sizeof(context));
320
321 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
322
323 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
324#ifdef CONFIG_CRUNCH
325 if (err == 0)
326 err |= preserve_crunch_context(&aux->crunch);
327#endif
328#ifdef CONFIG_IWMMXT
329 if (err == 0)
330 err |= preserve_iwmmxt_context(&aux->iwmmxt);
331#endif
332#ifdef CONFIG_VFP
333 if (err == 0)
334 err |= preserve_vfp_context(&aux->vfp);
335#endif
336 err |= __put_user(0, &aux->end_magic);
337
338 return err;
339}
340
341static inline void __user *
342get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
343{
344 unsigned long sp = sigsp(regs->ARM_sp, ksig);
345 void __user *frame;
346
347 /*
348 * ATPCS B01 mandates 8-byte alignment
349 */
350 frame = (void __user *)((sp - framesize) & ~7);
351
352 /*
353 * Check that we can actually write to the signal frame.
354 */
355 if (!access_ok(frame, framesize))
356 frame = NULL;
357
358 return frame;
359}
360
361static int
362setup_return(struct pt_regs *regs, struct ksignal *ksig,
363 unsigned long __user *rc, void __user *frame)
364{
365 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
366 unsigned long handler_fdpic_GOT = 0;
367 unsigned long retcode;
368 unsigned int idx, thumb = 0;
369 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
370 bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) &&
371 (current->personality & FDPIC_FUNCPTRS);
372
373 if (fdpic) {
374 unsigned long __user *fdpic_func_desc =
375 (unsigned long __user *)handler;
376 if (__get_user(handler, &fdpic_func_desc[0]) ||
377 __get_user(handler_fdpic_GOT, &fdpic_func_desc[1]))
378 return 1;
379 }
380
381 cpsr |= PSR_ENDSTATE;
382
383 /*
384 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
385 */
386 if (ksig->ka.sa.sa_flags & SA_THIRTYTWO)
387 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
388
389#ifdef CONFIG_ARM_THUMB
390 if (elf_hwcap & HWCAP_THUMB) {
391 /*
392 * The LSB of the handler determines if we're going to
393 * be using THUMB or ARM mode for this signal handler.
394 */
395 thumb = handler & 1;
396
397 /*
398 * Clear the If-Then Thumb-2 execution state. ARM spec
399 * requires this to be all 000s in ARM mode. Snapdragon
400 * S4/Krait misbehaves on a Thumb=>ARM signal transition
401 * without this.
402 *
403 * We must do this whenever we are running on a Thumb-2
404 * capable CPU, which includes ARMv6T2. However, we elect
405 * to always do this to simplify the code; this field is
406 * marked UNK/SBZP for older architectures.
407 */
408 cpsr &= ~PSR_IT_MASK;
409
410 if (thumb) {
411 cpsr |= PSR_T_BIT;
412 } else
413 cpsr &= ~PSR_T_BIT;
414 }
415#endif
416
417 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
418 retcode = (unsigned long)ksig->ka.sa.sa_restorer;
419 if (fdpic) {
420 /*
421 * We need code to load the function descriptor.
422 * That code follows the standard sigreturn code
423 * (6 words), and is made of 3 + 2 words for each
424 * variant. The 4th copied word is the actual FD
425 * address that the assembly code expects.
426 */
427 idx = 6 + thumb * 3;
428 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
429 idx += 5;
430 if (__put_user(sigreturn_codes[idx], rc ) ||
431 __put_user(sigreturn_codes[idx+1], rc+1) ||
432 __put_user(sigreturn_codes[idx+2], rc+2) ||
433 __put_user(retcode, rc+3))
434 return 1;
435 goto rc_finish;
436 }
437 } else {
438 idx = thumb << 1;
439 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
440 idx += 3;
441
442 /*
443 * Put the sigreturn code on the stack no matter which return
444 * mechanism we use in order to remain ABI compliant
445 */
446 if (__put_user(sigreturn_codes[idx], rc) ||
447 __put_user(sigreturn_codes[idx+1], rc+1))
448 return 1;
449
450rc_finish:
451#ifdef CONFIG_MMU
452 if (cpsr & MODE32_BIT) {
453 struct mm_struct *mm = current->mm;
454
455 /*
456 * 32-bit code can use the signal return page
457 * except when the MPU has protected the vectors
458 * page from PL0
459 */
460 retcode = mm->context.sigpage + signal_return_offset +
461 (idx << 2) + thumb;
462 } else
463#endif
464 {
465 /*
466 * Ensure that the instruction cache sees
467 * the return code written onto the stack.
468 */
469 flush_icache_range((unsigned long)rc,
470 (unsigned long)(rc + 3));
471
472 retcode = ((unsigned long)rc) + thumb;
473 }
474 }
475
476 regs->ARM_r0 = ksig->sig;
477 regs->ARM_sp = (unsigned long)frame;
478 regs->ARM_lr = retcode;
479 regs->ARM_pc = handler;
480 if (fdpic)
481 regs->ARM_r9 = handler_fdpic_GOT;
482 regs->ARM_cpsr = cpsr;
483
484 return 0;
485}
486
487static int
488setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
489{
490 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
491 int err = 0;
492
493 if (!frame)
494 return 1;
495
496 /*
497 * Set uc.uc_flags to a value which sc.trap_no would never have.
498 */
499 err = __put_user(0x5ac3c35a, &frame->uc.uc_flags);
500
501 err |= setup_sigframe(frame, regs, set);
502 if (err == 0)
503 err = setup_return(regs, ksig, frame->retcode, frame);
504
505 return err;
506}
507
508static int
509setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
510{
511 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
512 int err = 0;
513
514 if (!frame)
515 return 1;
516
517 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
518
519 err |= __put_user(0, &frame->sig.uc.uc_flags);
520 err |= __put_user(NULL, &frame->sig.uc.uc_link);
521
522 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp);
523 err |= setup_sigframe(&frame->sig, regs, set);
524 if (err == 0)
525 err = setup_return(regs, ksig, frame->sig.retcode, frame);
526
527 if (err == 0) {
528 /*
529 * For realtime signals we must also set the second and third
530 * arguments for the signal handler.
531 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
532 */
533 regs->ARM_r1 = (unsigned long)&frame->info;
534 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
535 }
536
537 return err;
538}
539
540/*
541 * OK, we're invoking a handler
542 */
543static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
544{
545 sigset_t *oldset = sigmask_to_save();
546 int ret;
547
548 /*
549 * Perform fixup for the pre-signal frame.
550 */
551 rseq_signal_deliver(ksig, regs);
552
553 /*
554 * Set up the stack frame
555 */
556 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
557 ret = setup_rt_frame(ksig, oldset, regs);
558 else
559 ret = setup_frame(ksig, oldset, regs);
560
561 /*
562 * Check that the resulting registers are actually sane.
563 */
564 ret |= !valid_user_regs(regs);
565
566 signal_setup_done(ret, ksig, 0);
567}
568
569/*
570 * Note that 'init' is a special process: it doesn't get signals it doesn't
571 * want to handle. Thus you cannot kill init even with a SIGKILL even by
572 * mistake.
573 *
574 * Note that we go through the signals twice: once to check the signals that
575 * the kernel can handle, and then we build all the user-level signal handling
576 * stack-frames in one go after that.
577 */
578static int do_signal(struct pt_regs *regs, int syscall)
579{
580 unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
581 struct ksignal ksig;
582 int restart = 0;
583
584 /*
585 * If we were from a system call, check for system call restarting...
586 */
587 if (syscall) {
588 continue_addr = regs->ARM_pc;
589 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
590 retval = regs->ARM_r0;
591
592 /*
593 * Prepare for system call restart. We do this here so that a
594 * debugger will see the already changed PSW.
595 */
596 switch (retval) {
597 case -ERESTART_RESTARTBLOCK:
598 restart -= 2;
599 fallthrough;
600 case -ERESTARTNOHAND:
601 case -ERESTARTSYS:
602 case -ERESTARTNOINTR:
603 restart++;
604 regs->ARM_r0 = regs->ARM_ORIG_r0;
605 regs->ARM_pc = restart_addr;
606 break;
607 }
608 }
609
610 /*
611 * Get the signal to deliver. When running under ptrace, at this
612 * point the debugger may change all our registers ...
613 */
614 /*
615 * Depending on the signal settings we may need to revert the
616 * decision to restart the system call. But skip this if a
617 * debugger has chosen to restart at a different PC.
618 */
619 if (get_signal(&ksig)) {
620 /* handler */
621 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
622 if (retval == -ERESTARTNOHAND ||
623 retval == -ERESTART_RESTARTBLOCK
624 || (retval == -ERESTARTSYS
625 && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
626 regs->ARM_r0 = -EINTR;
627 regs->ARM_pc = continue_addr;
628 }
629 }
630 handle_signal(&ksig, regs);
631 } else {
632 /* no handler */
633 restore_saved_sigmask();
634 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
635 regs->ARM_pc = continue_addr;
636 return restart;
637 }
638 }
639 return 0;
640}
641
642asmlinkage int
643do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
644{
645 /*
646 * The assembly code enters us with IRQs off, but it hasn't
647 * informed the tracing code of that for efficiency reasons.
648 * Update the trace code with the current status.
649 */
650 trace_hardirqs_off();
651 do {
652 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
653 schedule();
654 } else {
655 if (unlikely(!user_mode(regs)))
656 return 0;
657 local_irq_enable();
658 if (thread_flags & _TIF_SIGPENDING) {
659 int restart = do_signal(regs, syscall);
660 if (unlikely(restart)) {
661 /*
662 * Restart without handlers.
663 * Deal with it without leaving
664 * the kernel space.
665 */
666 return restart;
667 }
668 syscall = 0;
669 } else if (thread_flags & _TIF_UPROBE) {
670 uprobe_notify_resume(regs);
671 } else {
672 clear_thread_flag(TIF_NOTIFY_RESUME);
673 tracehook_notify_resume(regs);
674 rseq_handle_notify_resume(NULL, regs);
675 }
676 }
677 local_irq_disable();
678 thread_flags = current_thread_info()->flags;
679 } while (thread_flags & _TIF_WORK_MASK);
680 return 0;
681}
682
683struct page *get_signal_page(void)
684{
685 unsigned long ptr;
686 unsigned offset;
687 struct page *page;
688 void *addr;
689
690 page = alloc_pages(GFP_KERNEL, 0);
691
692 if (!page)
693 return NULL;
694
695 addr = page_address(page);
696
697 /* Give the signal return code some randomness */
698 offset = 0x200 + (get_random_int() & 0x7fc);
699 signal_return_offset = offset;
700
701 /*
702 * Copy signal return handlers into the vector page, and
703 * set sigreturn to be a pointer to these.
704 */
705 memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
706
707 ptr = (unsigned long)addr + offset;
708 flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
709
710 return page;
711}
712
713/* Defer to generic check */
714asmlinkage void addr_limit_check_failed(void)
715{
716#ifdef CONFIG_MMU
717 addr_limit_user_check();
718#endif
719}
720
721#ifdef CONFIG_DEBUG_RSEQ
722asmlinkage void do_rseq_syscall(struct pt_regs *regs)
723{
724 rseq_syscall(regs);
725}
726#endif
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/arm/kernel/signal.c
4 *
5 * Copyright (C) 1995-2009 Russell King
6 */
7#include <linux/errno.h>
8#include <linux/random.h>
9#include <linux/signal.h>
10#include <linux/personality.h>
11#include <linux/uaccess.h>
12#include <linux/tracehook.h>
13#include <linux/uprobes.h>
14#include <linux/syscalls.h>
15
16#include <asm/elf.h>
17#include <asm/cacheflush.h>
18#include <asm/traps.h>
19#include <asm/unistd.h>
20#include <asm/vfp.h>
21
22#include "signal.h"
23
24extern const unsigned long sigreturn_codes[17];
25
26static unsigned long signal_return_offset;
27
28#ifdef CONFIG_CRUNCH
29static int preserve_crunch_context(struct crunch_sigframe __user *frame)
30{
31 char kbuf[sizeof(*frame) + 8];
32 struct crunch_sigframe *kframe;
33
34 /* the crunch context must be 64 bit aligned */
35 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
36 kframe->magic = CRUNCH_MAGIC;
37 kframe->size = CRUNCH_STORAGE_SIZE;
38 crunch_task_copy(current_thread_info(), &kframe->storage);
39 return __copy_to_user(frame, kframe, sizeof(*frame));
40}
41
42static int restore_crunch_context(char __user **auxp)
43{
44 struct crunch_sigframe __user *frame =
45 (struct crunch_sigframe __user *)*auxp;
46 char kbuf[sizeof(*frame) + 8];
47 struct crunch_sigframe *kframe;
48
49 /* the crunch context must be 64 bit aligned */
50 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
51 if (__copy_from_user(kframe, frame, sizeof(*frame)))
52 return -1;
53 if (kframe->magic != CRUNCH_MAGIC ||
54 kframe->size != CRUNCH_STORAGE_SIZE)
55 return -1;
56 *auxp += CRUNCH_STORAGE_SIZE;
57 crunch_task_restore(current_thread_info(), &kframe->storage);
58 return 0;
59}
60#endif
61
62#ifdef CONFIG_IWMMXT
63
64static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame)
65{
66 char kbuf[sizeof(*frame) + 8];
67 struct iwmmxt_sigframe *kframe;
68 int err = 0;
69
70 /* the iWMMXt context must be 64 bit aligned */
71 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
72
73 if (test_thread_flag(TIF_USING_IWMMXT)) {
74 kframe->magic = IWMMXT_MAGIC;
75 kframe->size = IWMMXT_STORAGE_SIZE;
76 iwmmxt_task_copy(current_thread_info(), &kframe->storage);
77 } else {
78 /*
79 * For bug-compatibility with older kernels, some space
80 * has to be reserved for iWMMXt even if it's not used.
81 * Set the magic and size appropriately so that properly
82 * written userspace can skip it reliably:
83 */
84 *kframe = (struct iwmmxt_sigframe) {
85 .magic = DUMMY_MAGIC,
86 .size = IWMMXT_STORAGE_SIZE,
87 };
88 }
89
90 err = __copy_to_user(frame, kframe, sizeof(*kframe));
91
92 return err;
93}
94
95static int restore_iwmmxt_context(char __user **auxp)
96{
97 struct iwmmxt_sigframe __user *frame =
98 (struct iwmmxt_sigframe __user *)*auxp;
99 char kbuf[sizeof(*frame) + 8];
100 struct iwmmxt_sigframe *kframe;
101
102 /* the iWMMXt context must be 64 bit aligned */
103 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
104 if (__copy_from_user(kframe, frame, sizeof(*frame)))
105 return -1;
106
107 /*
108 * For non-iWMMXt threads: a single iwmmxt_sigframe-sized dummy
109 * block is discarded for compatibility with setup_sigframe() if
110 * present, but we don't mandate its presence. If some other
111 * magic is here, it's not for us:
112 */
113 if (!test_thread_flag(TIF_USING_IWMMXT) &&
114 kframe->magic != DUMMY_MAGIC)
115 return 0;
116
117 if (kframe->size != IWMMXT_STORAGE_SIZE)
118 return -1;
119
120 if (test_thread_flag(TIF_USING_IWMMXT)) {
121 if (kframe->magic != IWMMXT_MAGIC)
122 return -1;
123
124 iwmmxt_task_restore(current_thread_info(), &kframe->storage);
125 }
126
127 *auxp += IWMMXT_STORAGE_SIZE;
128 return 0;
129}
130
131#endif
132
133#ifdef CONFIG_VFP
134
135static int preserve_vfp_context(struct vfp_sigframe __user *frame)
136{
137 struct vfp_sigframe kframe;
138 int err = 0;
139
140 memset(&kframe, 0, sizeof(kframe));
141 kframe.magic = VFP_MAGIC;
142 kframe.size = VFP_STORAGE_SIZE;
143
144 err = vfp_preserve_user_clear_hwstate(&kframe.ufp, &kframe.ufp_exc);
145 if (err)
146 return err;
147
148 return __copy_to_user(frame, &kframe, sizeof(kframe));
149}
150
151static int restore_vfp_context(char __user **auxp)
152{
153 struct vfp_sigframe frame;
154 int err;
155
156 err = __copy_from_user(&frame, *auxp, sizeof(frame));
157 if (err)
158 return err;
159
160 if (frame.magic != VFP_MAGIC || frame.size != VFP_STORAGE_SIZE)
161 return -EINVAL;
162
163 *auxp += sizeof(frame);
164 return vfp_restore_user_hwstate(&frame.ufp, &frame.ufp_exc);
165}
166
167#endif
168
169/*
170 * Do a signal return; undo the signal stack. These are aligned to 64-bit.
171 */
172
173static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
174{
175 struct sigcontext context;
176 char __user *aux;
177 sigset_t set;
178 int err;
179
180 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
181 if (err == 0)
182 set_current_blocked(&set);
183
184 err |= __copy_from_user(&context, &sf->uc.uc_mcontext, sizeof(context));
185 if (err == 0) {
186 regs->ARM_r0 = context.arm_r0;
187 regs->ARM_r1 = context.arm_r1;
188 regs->ARM_r2 = context.arm_r2;
189 regs->ARM_r3 = context.arm_r3;
190 regs->ARM_r4 = context.arm_r4;
191 regs->ARM_r5 = context.arm_r5;
192 regs->ARM_r6 = context.arm_r6;
193 regs->ARM_r7 = context.arm_r7;
194 regs->ARM_r8 = context.arm_r8;
195 regs->ARM_r9 = context.arm_r9;
196 regs->ARM_r10 = context.arm_r10;
197 regs->ARM_fp = context.arm_fp;
198 regs->ARM_ip = context.arm_ip;
199 regs->ARM_sp = context.arm_sp;
200 regs->ARM_lr = context.arm_lr;
201 regs->ARM_pc = context.arm_pc;
202 regs->ARM_cpsr = context.arm_cpsr;
203 }
204
205 err |= !valid_user_regs(regs);
206
207 aux = (char __user *) sf->uc.uc_regspace;
208#ifdef CONFIG_CRUNCH
209 if (err == 0)
210 err |= restore_crunch_context(&aux);
211#endif
212#ifdef CONFIG_IWMMXT
213 if (err == 0)
214 err |= restore_iwmmxt_context(&aux);
215#endif
216#ifdef CONFIG_VFP
217 if (err == 0)
218 err |= restore_vfp_context(&aux);
219#endif
220
221 return err;
222}
223
224asmlinkage int sys_sigreturn(struct pt_regs *regs)
225{
226 struct sigframe __user *frame;
227
228 /* Always make any pending restarted system calls return -EINTR */
229 current->restart_block.fn = do_no_restart_syscall;
230
231 /*
232 * Since we stacked the signal on a 64-bit boundary,
233 * then 'sp' should be word aligned here. If it's
234 * not, then the user is trying to mess with us.
235 */
236 if (regs->ARM_sp & 7)
237 goto badframe;
238
239 frame = (struct sigframe __user *)regs->ARM_sp;
240
241 if (!access_ok(frame, sizeof (*frame)))
242 goto badframe;
243
244 if (restore_sigframe(regs, frame))
245 goto badframe;
246
247 return regs->ARM_r0;
248
249badframe:
250 force_sig(SIGSEGV);
251 return 0;
252}
253
254asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
255{
256 struct rt_sigframe __user *frame;
257
258 /* Always make any pending restarted system calls return -EINTR */
259 current->restart_block.fn = do_no_restart_syscall;
260
261 /*
262 * Since we stacked the signal on a 64-bit boundary,
263 * then 'sp' should be word aligned here. If it's
264 * not, then the user is trying to mess with us.
265 */
266 if (regs->ARM_sp & 7)
267 goto badframe;
268
269 frame = (struct rt_sigframe __user *)regs->ARM_sp;
270
271 if (!access_ok(frame, sizeof (*frame)))
272 goto badframe;
273
274 if (restore_sigframe(regs, &frame->sig))
275 goto badframe;
276
277 if (restore_altstack(&frame->sig.uc.uc_stack))
278 goto badframe;
279
280 return regs->ARM_r0;
281
282badframe:
283 force_sig(SIGSEGV);
284 return 0;
285}
286
287static int
288setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
289{
290 struct aux_sigframe __user *aux;
291 struct sigcontext context;
292 int err = 0;
293
294 context = (struct sigcontext) {
295 .arm_r0 = regs->ARM_r0,
296 .arm_r1 = regs->ARM_r1,
297 .arm_r2 = regs->ARM_r2,
298 .arm_r3 = regs->ARM_r3,
299 .arm_r4 = regs->ARM_r4,
300 .arm_r5 = regs->ARM_r5,
301 .arm_r6 = regs->ARM_r6,
302 .arm_r7 = regs->ARM_r7,
303 .arm_r8 = regs->ARM_r8,
304 .arm_r9 = regs->ARM_r9,
305 .arm_r10 = regs->ARM_r10,
306 .arm_fp = regs->ARM_fp,
307 .arm_ip = regs->ARM_ip,
308 .arm_sp = regs->ARM_sp,
309 .arm_lr = regs->ARM_lr,
310 .arm_pc = regs->ARM_pc,
311 .arm_cpsr = regs->ARM_cpsr,
312
313 .trap_no = current->thread.trap_no,
314 .error_code = current->thread.error_code,
315 .fault_address = current->thread.address,
316 .oldmask = set->sig[0],
317 };
318
319 err |= __copy_to_user(&sf->uc.uc_mcontext, &context, sizeof(context));
320
321 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
322
323 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
324#ifdef CONFIG_CRUNCH
325 if (err == 0)
326 err |= preserve_crunch_context(&aux->crunch);
327#endif
328#ifdef CONFIG_IWMMXT
329 if (err == 0)
330 err |= preserve_iwmmxt_context(&aux->iwmmxt);
331#endif
332#ifdef CONFIG_VFP
333 if (err == 0)
334 err |= preserve_vfp_context(&aux->vfp);
335#endif
336 err |= __put_user(0, &aux->end_magic);
337
338 return err;
339}
340
341static inline void __user *
342get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
343{
344 unsigned long sp = sigsp(regs->ARM_sp, ksig);
345 void __user *frame;
346
347 /*
348 * ATPCS B01 mandates 8-byte alignment
349 */
350 frame = (void __user *)((sp - framesize) & ~7);
351
352 /*
353 * Check that we can actually write to the signal frame.
354 */
355 if (!access_ok(frame, framesize))
356 frame = NULL;
357
358 return frame;
359}
360
361static int
362setup_return(struct pt_regs *regs, struct ksignal *ksig,
363 unsigned long __user *rc, void __user *frame)
364{
365 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
366 unsigned long handler_fdpic_GOT = 0;
367 unsigned long retcode;
368 unsigned int idx, thumb = 0;
369 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
370 bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) &&
371 (current->personality & FDPIC_FUNCPTRS);
372
373 if (fdpic) {
374 unsigned long __user *fdpic_func_desc =
375 (unsigned long __user *)handler;
376 if (__get_user(handler, &fdpic_func_desc[0]) ||
377 __get_user(handler_fdpic_GOT, &fdpic_func_desc[1]))
378 return 1;
379 }
380
381 cpsr |= PSR_ENDSTATE;
382
383 /*
384 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
385 */
386 if (ksig->ka.sa.sa_flags & SA_THIRTYTWO)
387 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
388
389#ifdef CONFIG_ARM_THUMB
390 if (elf_hwcap & HWCAP_THUMB) {
391 /*
392 * The LSB of the handler determines if we're going to
393 * be using THUMB or ARM mode for this signal handler.
394 */
395 thumb = handler & 1;
396
397 /*
398 * Clear the If-Then Thumb-2 execution state. ARM spec
399 * requires this to be all 000s in ARM mode. Snapdragon
400 * S4/Krait misbehaves on a Thumb=>ARM signal transition
401 * without this.
402 *
403 * We must do this whenever we are running on a Thumb-2
404 * capable CPU, which includes ARMv6T2. However, we elect
405 * to always do this to simplify the code; this field is
406 * marked UNK/SBZP for older architectures.
407 */
408 cpsr &= ~PSR_IT_MASK;
409
410 if (thumb) {
411 cpsr |= PSR_T_BIT;
412 } else
413 cpsr &= ~PSR_T_BIT;
414 }
415#endif
416
417 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
418 retcode = (unsigned long)ksig->ka.sa.sa_restorer;
419 if (fdpic) {
420 /*
421 * We need code to load the function descriptor.
422 * That code follows the standard sigreturn code
423 * (6 words), and is made of 3 + 2 words for each
424 * variant. The 4th copied word is the actual FD
425 * address that the assembly code expects.
426 */
427 idx = 6 + thumb * 3;
428 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
429 idx += 5;
430 if (__put_user(sigreturn_codes[idx], rc ) ||
431 __put_user(sigreturn_codes[idx+1], rc+1) ||
432 __put_user(sigreturn_codes[idx+2], rc+2) ||
433 __put_user(retcode, rc+3))
434 return 1;
435 goto rc_finish;
436 }
437 } else {
438 idx = thumb << 1;
439 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
440 idx += 3;
441
442 /*
443 * Put the sigreturn code on the stack no matter which return
444 * mechanism we use in order to remain ABI compliant
445 */
446 if (__put_user(sigreturn_codes[idx], rc) ||
447 __put_user(sigreturn_codes[idx+1], rc+1))
448 return 1;
449
450rc_finish:
451#ifdef CONFIG_MMU
452 if (cpsr & MODE32_BIT) {
453 struct mm_struct *mm = current->mm;
454
455 /*
456 * 32-bit code can use the signal return page
457 * except when the MPU has protected the vectors
458 * page from PL0
459 */
460 retcode = mm->context.sigpage + signal_return_offset +
461 (idx << 2) + thumb;
462 } else
463#endif
464 {
465 /*
466 * Ensure that the instruction cache sees
467 * the return code written onto the stack.
468 */
469 flush_icache_range((unsigned long)rc,
470 (unsigned long)(rc + 3));
471
472 retcode = ((unsigned long)rc) + thumb;
473 }
474 }
475
476 regs->ARM_r0 = ksig->sig;
477 regs->ARM_sp = (unsigned long)frame;
478 regs->ARM_lr = retcode;
479 regs->ARM_pc = handler;
480 if (fdpic)
481 regs->ARM_r9 = handler_fdpic_GOT;
482 regs->ARM_cpsr = cpsr;
483
484 return 0;
485}
486
487static int
488setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
489{
490 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
491 int err = 0;
492
493 if (!frame)
494 return 1;
495
496 /*
497 * Set uc.uc_flags to a value which sc.trap_no would never have.
498 */
499 err = __put_user(0x5ac3c35a, &frame->uc.uc_flags);
500
501 err |= setup_sigframe(frame, regs, set);
502 if (err == 0)
503 err = setup_return(regs, ksig, frame->retcode, frame);
504
505 return err;
506}
507
508static int
509setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
510{
511 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
512 int err = 0;
513
514 if (!frame)
515 return 1;
516
517 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
518
519 err |= __put_user(0, &frame->sig.uc.uc_flags);
520 err |= __put_user(NULL, &frame->sig.uc.uc_link);
521
522 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp);
523 err |= setup_sigframe(&frame->sig, regs, set);
524 if (err == 0)
525 err = setup_return(regs, ksig, frame->sig.retcode, frame);
526
527 if (err == 0) {
528 /*
529 * For realtime signals we must also set the second and third
530 * arguments for the signal handler.
531 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
532 */
533 regs->ARM_r1 = (unsigned long)&frame->info;
534 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
535 }
536
537 return err;
538}
539
540/*
541 * OK, we're invoking a handler
542 */
543static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
544{
545 sigset_t *oldset = sigmask_to_save();
546 int ret;
547
548 /*
549 * Perform fixup for the pre-signal frame.
550 */
551 rseq_signal_deliver(ksig, regs);
552
553 /*
554 * Set up the stack frame
555 */
556 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
557 ret = setup_rt_frame(ksig, oldset, regs);
558 else
559 ret = setup_frame(ksig, oldset, regs);
560
561 /*
562 * Check that the resulting registers are actually sane.
563 */
564 ret |= !valid_user_regs(regs);
565
566 signal_setup_done(ret, ksig, 0);
567}
568
569/*
570 * Note that 'init' is a special process: it doesn't get signals it doesn't
571 * want to handle. Thus you cannot kill init even with a SIGKILL even by
572 * mistake.
573 *
574 * Note that we go through the signals twice: once to check the signals that
575 * the kernel can handle, and then we build all the user-level signal handling
576 * stack-frames in one go after that.
577 */
578static int do_signal(struct pt_regs *regs, int syscall)
579{
580 unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
581 struct ksignal ksig;
582 int restart = 0;
583
584 /*
585 * If we were from a system call, check for system call restarting...
586 */
587 if (syscall) {
588 continue_addr = regs->ARM_pc;
589 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
590 retval = regs->ARM_r0;
591
592 /*
593 * Prepare for system call restart. We do this here so that a
594 * debugger will see the already changed PSW.
595 */
596 switch (retval) {
597 case -ERESTART_RESTARTBLOCK:
598 restart -= 2;
599 /* Fall through */
600 case -ERESTARTNOHAND:
601 case -ERESTARTSYS:
602 case -ERESTARTNOINTR:
603 restart++;
604 regs->ARM_r0 = regs->ARM_ORIG_r0;
605 regs->ARM_pc = restart_addr;
606 break;
607 }
608 }
609
610 /*
611 * Get the signal to deliver. When running under ptrace, at this
612 * point the debugger may change all our registers ...
613 */
614 /*
615 * Depending on the signal settings we may need to revert the
616 * decision to restart the system call. But skip this if a
617 * debugger has chosen to restart at a different PC.
618 */
619 if (get_signal(&ksig)) {
620 /* handler */
621 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
622 if (retval == -ERESTARTNOHAND ||
623 retval == -ERESTART_RESTARTBLOCK
624 || (retval == -ERESTARTSYS
625 && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
626 regs->ARM_r0 = -EINTR;
627 regs->ARM_pc = continue_addr;
628 }
629 }
630 handle_signal(&ksig, regs);
631 } else {
632 /* no handler */
633 restore_saved_sigmask();
634 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
635 regs->ARM_pc = continue_addr;
636 return restart;
637 }
638 }
639 return 0;
640}
641
642asmlinkage int
643do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
644{
645 /*
646 * The assembly code enters us with IRQs off, but it hasn't
647 * informed the tracing code of that for efficiency reasons.
648 * Update the trace code with the current status.
649 */
650 trace_hardirqs_off();
651 do {
652 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
653 schedule();
654 } else {
655 if (unlikely(!user_mode(regs)))
656 return 0;
657 local_irq_enable();
658 if (thread_flags & _TIF_SIGPENDING) {
659 int restart = do_signal(regs, syscall);
660 if (unlikely(restart)) {
661 /*
662 * Restart without handlers.
663 * Deal with it without leaving
664 * the kernel space.
665 */
666 return restart;
667 }
668 syscall = 0;
669 } else if (thread_flags & _TIF_UPROBE) {
670 uprobe_notify_resume(regs);
671 } else {
672 clear_thread_flag(TIF_NOTIFY_RESUME);
673 tracehook_notify_resume(regs);
674 rseq_handle_notify_resume(NULL, regs);
675 }
676 }
677 local_irq_disable();
678 thread_flags = current_thread_info()->flags;
679 } while (thread_flags & _TIF_WORK_MASK);
680 return 0;
681}
682
683struct page *get_signal_page(void)
684{
685 unsigned long ptr;
686 unsigned offset;
687 struct page *page;
688 void *addr;
689
690 page = alloc_pages(GFP_KERNEL, 0);
691
692 if (!page)
693 return NULL;
694
695 addr = page_address(page);
696
697 /* Give the signal return code some randomness */
698 offset = 0x200 + (get_random_int() & 0x7fc);
699 signal_return_offset = offset;
700
701 /*
702 * Copy signal return handlers into the vector page, and
703 * set sigreturn to be a pointer to these.
704 */
705 memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
706
707 ptr = (unsigned long)addr + offset;
708 flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
709
710 return page;
711}
712
713/* Defer to generic check */
714asmlinkage void addr_limit_check_failed(void)
715{
716 addr_limit_user_check();
717}
718
719#ifdef CONFIG_DEBUG_RSEQ
720asmlinkage void do_rseq_syscall(struct pt_regs *regs)
721{
722 rseq_syscall(regs);
723}
724#endif