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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/resume_user_mode.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#include <asm/syscalls.h>
22
23#include "signal.h"
24
25extern const unsigned long sigreturn_codes[17];
26
27static unsigned long signal_return_offset;
28
29#ifdef CONFIG_IWMMXT
30
31static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame)
32{
33 char kbuf[sizeof(*frame) + 8];
34 struct iwmmxt_sigframe *kframe;
35 int err = 0;
36
37 /* the iWMMXt context must be 64 bit aligned */
38 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
39
40 if (test_thread_flag(TIF_USING_IWMMXT)) {
41 kframe->magic = IWMMXT_MAGIC;
42 kframe->size = IWMMXT_STORAGE_SIZE;
43 iwmmxt_task_copy(current_thread_info(), &kframe->storage);
44 } else {
45 /*
46 * For bug-compatibility with older kernels, some space
47 * has to be reserved for iWMMXt even if it's not used.
48 * Set the magic and size appropriately so that properly
49 * written userspace can skip it reliably:
50 */
51 *kframe = (struct iwmmxt_sigframe) {
52 .magic = DUMMY_MAGIC,
53 .size = IWMMXT_STORAGE_SIZE,
54 };
55 }
56
57 err = __copy_to_user(frame, kframe, sizeof(*kframe));
58
59 return err;
60}
61
62static int restore_iwmmxt_context(char __user **auxp)
63{
64 struct iwmmxt_sigframe __user *frame =
65 (struct iwmmxt_sigframe __user *)*auxp;
66 char kbuf[sizeof(*frame) + 8];
67 struct iwmmxt_sigframe *kframe;
68
69 /* the iWMMXt context must be 64 bit aligned */
70 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
71 if (__copy_from_user(kframe, frame, sizeof(*frame)))
72 return -1;
73
74 /*
75 * For non-iWMMXt threads: a single iwmmxt_sigframe-sized dummy
76 * block is discarded for compatibility with setup_sigframe() if
77 * present, but we don't mandate its presence. If some other
78 * magic is here, it's not for us:
79 */
80 if (!test_thread_flag(TIF_USING_IWMMXT) &&
81 kframe->magic != DUMMY_MAGIC)
82 return 0;
83
84 if (kframe->size != IWMMXT_STORAGE_SIZE)
85 return -1;
86
87 if (test_thread_flag(TIF_USING_IWMMXT)) {
88 if (kframe->magic != IWMMXT_MAGIC)
89 return -1;
90
91 iwmmxt_task_restore(current_thread_info(), &kframe->storage);
92 }
93
94 *auxp += IWMMXT_STORAGE_SIZE;
95 return 0;
96}
97
98#endif
99
100#ifdef CONFIG_VFP
101
102static int preserve_vfp_context(struct vfp_sigframe __user *frame)
103{
104 struct vfp_sigframe kframe;
105 int err = 0;
106
107 memset(&kframe, 0, sizeof(kframe));
108 kframe.magic = VFP_MAGIC;
109 kframe.size = VFP_STORAGE_SIZE;
110
111 err = vfp_preserve_user_clear_hwstate(&kframe.ufp, &kframe.ufp_exc);
112 if (err)
113 return err;
114
115 return __copy_to_user(frame, &kframe, sizeof(kframe));
116}
117
118static int restore_vfp_context(char __user **auxp)
119{
120 struct vfp_sigframe frame;
121 int err;
122
123 err = __copy_from_user(&frame, *auxp, sizeof(frame));
124 if (err)
125 return err;
126
127 if (frame.magic != VFP_MAGIC || frame.size != VFP_STORAGE_SIZE)
128 return -EINVAL;
129
130 *auxp += sizeof(frame);
131 return vfp_restore_user_hwstate(&frame.ufp, &frame.ufp_exc);
132}
133
134#endif
135
136/*
137 * Do a signal return; undo the signal stack. These are aligned to 64-bit.
138 */
139
140static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
141{
142 struct sigcontext context;
143 char __user *aux;
144 sigset_t set;
145 int err;
146
147 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
148 if (err == 0)
149 set_current_blocked(&set);
150
151 err |= __copy_from_user(&context, &sf->uc.uc_mcontext, sizeof(context));
152 if (err == 0) {
153 regs->ARM_r0 = context.arm_r0;
154 regs->ARM_r1 = context.arm_r1;
155 regs->ARM_r2 = context.arm_r2;
156 regs->ARM_r3 = context.arm_r3;
157 regs->ARM_r4 = context.arm_r4;
158 regs->ARM_r5 = context.arm_r5;
159 regs->ARM_r6 = context.arm_r6;
160 regs->ARM_r7 = context.arm_r7;
161 regs->ARM_r8 = context.arm_r8;
162 regs->ARM_r9 = context.arm_r9;
163 regs->ARM_r10 = context.arm_r10;
164 regs->ARM_fp = context.arm_fp;
165 regs->ARM_ip = context.arm_ip;
166 regs->ARM_sp = context.arm_sp;
167 regs->ARM_lr = context.arm_lr;
168 regs->ARM_pc = context.arm_pc;
169 regs->ARM_cpsr = context.arm_cpsr;
170 }
171
172 err |= !valid_user_regs(regs);
173
174 aux = (char __user *) sf->uc.uc_regspace;
175#ifdef CONFIG_IWMMXT
176 if (err == 0)
177 err |= restore_iwmmxt_context(&aux);
178#endif
179#ifdef CONFIG_VFP
180 if (err == 0)
181 err |= restore_vfp_context(&aux);
182#endif
183
184 return err;
185}
186
187asmlinkage int sys_sigreturn(struct pt_regs *regs)
188{
189 struct sigframe __user *frame;
190
191 /* Always make any pending restarted system calls return -EINTR */
192 current->restart_block.fn = do_no_restart_syscall;
193
194 /*
195 * Since we stacked the signal on a 64-bit boundary,
196 * then 'sp' should be word aligned here. If it's
197 * not, then the user is trying to mess with us.
198 */
199 if (regs->ARM_sp & 7)
200 goto badframe;
201
202 frame = (struct sigframe __user *)regs->ARM_sp;
203
204 if (!access_ok(frame, sizeof (*frame)))
205 goto badframe;
206
207 if (restore_sigframe(regs, frame))
208 goto badframe;
209
210 return regs->ARM_r0;
211
212badframe:
213 force_sig(SIGSEGV);
214 return 0;
215}
216
217asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
218{
219 struct rt_sigframe __user *frame;
220
221 /* Always make any pending restarted system calls return -EINTR */
222 current->restart_block.fn = do_no_restart_syscall;
223
224 /*
225 * Since we stacked the signal on a 64-bit boundary,
226 * then 'sp' should be word aligned here. If it's
227 * not, then the user is trying to mess with us.
228 */
229 if (regs->ARM_sp & 7)
230 goto badframe;
231
232 frame = (struct rt_sigframe __user *)regs->ARM_sp;
233
234 if (!access_ok(frame, sizeof (*frame)))
235 goto badframe;
236
237 if (restore_sigframe(regs, &frame->sig))
238 goto badframe;
239
240 if (restore_altstack(&frame->sig.uc.uc_stack))
241 goto badframe;
242
243 return regs->ARM_r0;
244
245badframe:
246 force_sig(SIGSEGV);
247 return 0;
248}
249
250static int
251setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
252{
253 struct aux_sigframe __user *aux;
254 struct sigcontext context;
255 int err = 0;
256
257 context = (struct sigcontext) {
258 .arm_r0 = regs->ARM_r0,
259 .arm_r1 = regs->ARM_r1,
260 .arm_r2 = regs->ARM_r2,
261 .arm_r3 = regs->ARM_r3,
262 .arm_r4 = regs->ARM_r4,
263 .arm_r5 = regs->ARM_r5,
264 .arm_r6 = regs->ARM_r6,
265 .arm_r7 = regs->ARM_r7,
266 .arm_r8 = regs->ARM_r8,
267 .arm_r9 = regs->ARM_r9,
268 .arm_r10 = regs->ARM_r10,
269 .arm_fp = regs->ARM_fp,
270 .arm_ip = regs->ARM_ip,
271 .arm_sp = regs->ARM_sp,
272 .arm_lr = regs->ARM_lr,
273 .arm_pc = regs->ARM_pc,
274 .arm_cpsr = regs->ARM_cpsr,
275
276 .trap_no = current->thread.trap_no,
277 .error_code = current->thread.error_code,
278 .fault_address = current->thread.address,
279 .oldmask = set->sig[0],
280 };
281
282 err |= __copy_to_user(&sf->uc.uc_mcontext, &context, sizeof(context));
283
284 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
285
286 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
287#ifdef CONFIG_IWMMXT
288 if (err == 0)
289 err |= preserve_iwmmxt_context(&aux->iwmmxt);
290#endif
291#ifdef CONFIG_VFP
292 if (err == 0)
293 err |= preserve_vfp_context(&aux->vfp);
294#endif
295 err |= __put_user(0, &aux->end_magic);
296
297 return err;
298}
299
300static inline void __user *
301get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
302{
303 unsigned long sp = sigsp(regs->ARM_sp, ksig);
304 void __user *frame;
305
306 /*
307 * ATPCS B01 mandates 8-byte alignment
308 */
309 frame = (void __user *)((sp - framesize) & ~7);
310
311 /*
312 * Check that we can actually write to the signal frame.
313 */
314 if (!access_ok(frame, framesize))
315 frame = NULL;
316
317 return frame;
318}
319
320static int
321setup_return(struct pt_regs *regs, struct ksignal *ksig,
322 unsigned long __user *rc, void __user *frame)
323{
324 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
325 unsigned long handler_fdpic_GOT = 0;
326 unsigned long retcode;
327 unsigned int idx, thumb = 0;
328 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
329 bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) &&
330 (current->personality & FDPIC_FUNCPTRS);
331
332 if (fdpic) {
333 unsigned long __user *fdpic_func_desc =
334 (unsigned long __user *)handler;
335 if (__get_user(handler, &fdpic_func_desc[0]) ||
336 __get_user(handler_fdpic_GOT, &fdpic_func_desc[1]))
337 return 1;
338 }
339
340 cpsr |= PSR_ENDSTATE;
341
342 /*
343 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
344 */
345 if (ksig->ka.sa.sa_flags & SA_THIRTYTWO)
346 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
347
348#ifdef CONFIG_ARM_THUMB
349 if (elf_hwcap & HWCAP_THUMB) {
350 /*
351 * The LSB of the handler determines if we're going to
352 * be using THUMB or ARM mode for this signal handler.
353 */
354 thumb = handler & 1;
355
356 /*
357 * Clear the If-Then Thumb-2 execution state. ARM spec
358 * requires this to be all 000s in ARM mode. Snapdragon
359 * S4/Krait misbehaves on a Thumb=>ARM signal transition
360 * without this.
361 *
362 * We must do this whenever we are running on a Thumb-2
363 * capable CPU, which includes ARMv6T2. However, we elect
364 * to always do this to simplify the code; this field is
365 * marked UNK/SBZP for older architectures.
366 */
367 cpsr &= ~PSR_IT_MASK;
368
369 if (thumb) {
370 cpsr |= PSR_T_BIT;
371 } else
372 cpsr &= ~PSR_T_BIT;
373 }
374#endif
375
376 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
377 retcode = (unsigned long)ksig->ka.sa.sa_restorer;
378 if (fdpic) {
379 /*
380 * We need code to load the function descriptor.
381 * That code follows the standard sigreturn code
382 * (6 words), and is made of 3 + 2 words for each
383 * variant. The 4th copied word is the actual FD
384 * address that the assembly code expects.
385 */
386 idx = 6 + thumb * 3;
387 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
388 idx += 5;
389 if (__put_user(sigreturn_codes[idx], rc ) ||
390 __put_user(sigreturn_codes[idx+1], rc+1) ||
391 __put_user(sigreturn_codes[idx+2], rc+2) ||
392 __put_user(retcode, rc+3))
393 return 1;
394 goto rc_finish;
395 }
396 } else {
397 idx = thumb << 1;
398 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
399 idx += 3;
400
401 /*
402 * Put the sigreturn code on the stack no matter which return
403 * mechanism we use in order to remain ABI compliant
404 */
405 if (__put_user(sigreturn_codes[idx], rc) ||
406 __put_user(sigreturn_codes[idx+1], rc+1))
407 return 1;
408
409rc_finish:
410#ifdef CONFIG_MMU
411 if (cpsr & MODE32_BIT) {
412 struct mm_struct *mm = current->mm;
413
414 /*
415 * 32-bit code can use the signal return page
416 * except when the MPU has protected the vectors
417 * page from PL0
418 */
419 retcode = mm->context.sigpage + signal_return_offset +
420 (idx << 2) + thumb;
421 } else
422#endif
423 {
424 /*
425 * Ensure that the instruction cache sees
426 * the return code written onto the stack.
427 */
428 flush_icache_range((unsigned long)rc,
429 (unsigned long)(rc + 3));
430
431 retcode = ((unsigned long)rc) + thumb;
432 }
433 }
434
435 regs->ARM_r0 = ksig->sig;
436 regs->ARM_sp = (unsigned long)frame;
437 regs->ARM_lr = retcode;
438 regs->ARM_pc = handler;
439 if (fdpic)
440 regs->ARM_r9 = handler_fdpic_GOT;
441 regs->ARM_cpsr = cpsr;
442
443 return 0;
444}
445
446static int
447setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
448{
449 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
450 int err = 0;
451
452 if (!frame)
453 return 1;
454
455 /*
456 * Set uc.uc_flags to a value which sc.trap_no would never have.
457 */
458 err = __put_user(0x5ac3c35a, &frame->uc.uc_flags);
459
460 err |= setup_sigframe(frame, regs, set);
461 if (err == 0)
462 err = setup_return(regs, ksig, frame->retcode, frame);
463
464 return err;
465}
466
467static int
468setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
469{
470 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
471 int err = 0;
472
473 if (!frame)
474 return 1;
475
476 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
477
478 err |= __put_user(0, &frame->sig.uc.uc_flags);
479 err |= __put_user(NULL, &frame->sig.uc.uc_link);
480
481 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp);
482 err |= setup_sigframe(&frame->sig, regs, set);
483 if (err == 0)
484 err = setup_return(regs, ksig, frame->sig.retcode, frame);
485
486 if (err == 0) {
487 /*
488 * For realtime signals we must also set the second and third
489 * arguments for the signal handler.
490 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
491 */
492 regs->ARM_r1 = (unsigned long)&frame->info;
493 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
494 }
495
496 return err;
497}
498
499/*
500 * OK, we're invoking a handler
501 */
502static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
503{
504 sigset_t *oldset = sigmask_to_save();
505 int ret;
506
507 /*
508 * Perform fixup for the pre-signal frame.
509 */
510 rseq_signal_deliver(ksig, regs);
511
512 /*
513 * Set up the stack frame
514 */
515 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
516 ret = setup_rt_frame(ksig, oldset, regs);
517 else
518 ret = setup_frame(ksig, oldset, regs);
519
520 /*
521 * Check that the resulting registers are actually sane.
522 */
523 ret |= !valid_user_regs(regs);
524
525 signal_setup_done(ret, ksig, 0);
526}
527
528/*
529 * Note that 'init' is a special process: it doesn't get signals it doesn't
530 * want to handle. Thus you cannot kill init even with a SIGKILL even by
531 * mistake.
532 *
533 * Note that we go through the signals twice: once to check the signals that
534 * the kernel can handle, and then we build all the user-level signal handling
535 * stack-frames in one go after that.
536 */
537static int do_signal(struct pt_regs *regs, int syscall)
538{
539 unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
540 struct ksignal ksig;
541 int restart = 0;
542
543 /*
544 * If we were from a system call, check for system call restarting...
545 */
546 if (syscall) {
547 continue_addr = regs->ARM_pc;
548 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
549 retval = regs->ARM_r0;
550
551 /*
552 * Prepare for system call restart. We do this here so that a
553 * debugger will see the already changed PSW.
554 */
555 switch (retval) {
556 case -ERESTART_RESTARTBLOCK:
557 restart -= 2;
558 fallthrough;
559 case -ERESTARTNOHAND:
560 case -ERESTARTSYS:
561 case -ERESTARTNOINTR:
562 restart++;
563 regs->ARM_r0 = regs->ARM_ORIG_r0;
564 regs->ARM_pc = restart_addr;
565 break;
566 }
567 }
568
569 /*
570 * Get the signal to deliver. When running under ptrace, at this
571 * point the debugger may change all our registers ...
572 */
573 /*
574 * Depending on the signal settings we may need to revert the
575 * decision to restart the system call. But skip this if a
576 * debugger has chosen to restart at a different PC.
577 */
578 if (get_signal(&ksig)) {
579 /* handler */
580 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
581 if (retval == -ERESTARTNOHAND ||
582 retval == -ERESTART_RESTARTBLOCK
583 || (retval == -ERESTARTSYS
584 && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
585 regs->ARM_r0 = -EINTR;
586 regs->ARM_pc = continue_addr;
587 }
588 }
589 handle_signal(&ksig, regs);
590 } else {
591 /* no handler */
592 restore_saved_sigmask();
593 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
594 regs->ARM_pc = continue_addr;
595 return restart;
596 }
597 }
598 return 0;
599}
600
601asmlinkage int
602do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
603{
604 /*
605 * The assembly code enters us with IRQs off, but it hasn't
606 * informed the tracing code of that for efficiency reasons.
607 * Update the trace code with the current status.
608 */
609 trace_hardirqs_off();
610 do {
611 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
612 schedule();
613 } else {
614 if (unlikely(!user_mode(regs)))
615 return 0;
616 local_irq_enable();
617 if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
618 int restart = do_signal(regs, syscall);
619 if (unlikely(restart)) {
620 /*
621 * Restart without handlers.
622 * Deal with it without leaving
623 * the kernel space.
624 */
625 return restart;
626 }
627 syscall = 0;
628 } else if (thread_flags & _TIF_UPROBE) {
629 uprobe_notify_resume(regs);
630 } else {
631 resume_user_mode_work(regs);
632 }
633 }
634 local_irq_disable();
635 thread_flags = read_thread_flags();
636 } while (thread_flags & _TIF_WORK_MASK);
637 return 0;
638}
639
640struct page *get_signal_page(void)
641{
642 unsigned long ptr;
643 unsigned offset;
644 struct page *page;
645 void *addr;
646
647 page = alloc_pages(GFP_KERNEL, 0);
648
649 if (!page)
650 return NULL;
651
652 addr = page_address(page);
653
654 /* Poison the entire page */
655 memset32(addr, __opcode_to_mem_arm(0xe7fddef1),
656 PAGE_SIZE / sizeof(u32));
657
658 /* Give the signal return code some randomness */
659 offset = 0x200 + (get_random_u16() & 0x7fc);
660 signal_return_offset = offset;
661
662 /* Copy signal return handlers into the page */
663 memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
664
665 /* Flush out all instructions in this page */
666 ptr = (unsigned long)addr;
667 flush_icache_range(ptr, ptr + PAGE_SIZE);
668
669 return page;
670}
671
672#ifdef CONFIG_DEBUG_RSEQ
673asmlinkage void do_rseq_syscall(struct pt_regs *regs)
674{
675 rseq_syscall(regs);
676}
677#endif
678
679/*
680 * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
681 * changes likely come with new fields that should be added below.
682 */
683static_assert(NSIGILL == 11);
684static_assert(NSIGFPE == 15);
685static_assert(NSIGSEGV == 10);
686static_assert(NSIGBUS == 5);
687static_assert(NSIGTRAP == 6);
688static_assert(NSIGCHLD == 6);
689static_assert(NSIGSYS == 2);
690static_assert(sizeof(siginfo_t) == 128);
691static_assert(__alignof__(siginfo_t) == 4);
692static_assert(offsetof(siginfo_t, si_signo) == 0x00);
693static_assert(offsetof(siginfo_t, si_errno) == 0x04);
694static_assert(offsetof(siginfo_t, si_code) == 0x08);
695static_assert(offsetof(siginfo_t, si_pid) == 0x0c);
696static_assert(offsetof(siginfo_t, si_uid) == 0x10);
697static_assert(offsetof(siginfo_t, si_tid) == 0x0c);
698static_assert(offsetof(siginfo_t, si_overrun) == 0x10);
699static_assert(offsetof(siginfo_t, si_status) == 0x14);
700static_assert(offsetof(siginfo_t, si_utime) == 0x18);
701static_assert(offsetof(siginfo_t, si_stime) == 0x1c);
702static_assert(offsetof(siginfo_t, si_value) == 0x14);
703static_assert(offsetof(siginfo_t, si_int) == 0x14);
704static_assert(offsetof(siginfo_t, si_ptr) == 0x14);
705static_assert(offsetof(siginfo_t, si_addr) == 0x0c);
706static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x10);
707static_assert(offsetof(siginfo_t, si_lower) == 0x14);
708static_assert(offsetof(siginfo_t, si_upper) == 0x18);
709static_assert(offsetof(siginfo_t, si_pkey) == 0x14);
710static_assert(offsetof(siginfo_t, si_perf_data) == 0x10);
711static_assert(offsetof(siginfo_t, si_perf_type) == 0x14);
712static_assert(offsetof(siginfo_t, si_perf_flags) == 0x18);
713static_assert(offsetof(siginfo_t, si_band) == 0x0c);
714static_assert(offsetof(siginfo_t, si_fd) == 0x10);
715static_assert(offsetof(siginfo_t, si_call_addr) == 0x0c);
716static_assert(offsetof(siginfo_t, si_syscall) == 0x10);
717static_assert(offsetof(siginfo_t, si_arch) == 0x14);
1/*
2 * linux/arch/arm/kernel/signal.c
3 *
4 * Copyright (C) 1995-2009 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10#include <linux/errno.h>
11#include <linux/random.h>
12#include <linux/signal.h>
13#include <linux/personality.h>
14#include <linux/uaccess.h>
15#include <linux/tracehook.h>
16#include <linux/uprobes.h>
17
18#include <asm/elf.h>
19#include <asm/cacheflush.h>
20#include <asm/traps.h>
21#include <asm/ucontext.h>
22#include <asm/unistd.h>
23#include <asm/vfp.h>
24
25extern const unsigned long sigreturn_codes[7];
26
27static unsigned long signal_return_offset;
28
29#ifdef CONFIG_CRUNCH
30static int preserve_crunch_context(struct crunch_sigframe __user *frame)
31{
32 char kbuf[sizeof(*frame) + 8];
33 struct crunch_sigframe *kframe;
34
35 /* the crunch context must be 64 bit aligned */
36 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
37 kframe->magic = CRUNCH_MAGIC;
38 kframe->size = CRUNCH_STORAGE_SIZE;
39 crunch_task_copy(current_thread_info(), &kframe->storage);
40 return __copy_to_user(frame, kframe, sizeof(*frame));
41}
42
43static int restore_crunch_context(struct crunch_sigframe __user *frame)
44{
45 char kbuf[sizeof(*frame) + 8];
46 struct crunch_sigframe *kframe;
47
48 /* the crunch context must be 64 bit aligned */
49 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
50 if (__copy_from_user(kframe, frame, sizeof(*frame)))
51 return -1;
52 if (kframe->magic != CRUNCH_MAGIC ||
53 kframe->size != CRUNCH_STORAGE_SIZE)
54 return -1;
55 crunch_task_restore(current_thread_info(), &kframe->storage);
56 return 0;
57}
58#endif
59
60#ifdef CONFIG_IWMMXT
61
62static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
63{
64 char kbuf[sizeof(*frame) + 8];
65 struct iwmmxt_sigframe *kframe;
66
67 /* the iWMMXt context must be 64 bit aligned */
68 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
69 kframe->magic = IWMMXT_MAGIC;
70 kframe->size = IWMMXT_STORAGE_SIZE;
71 iwmmxt_task_copy(current_thread_info(), &kframe->storage);
72 return __copy_to_user(frame, kframe, sizeof(*frame));
73}
74
75static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
76{
77 char kbuf[sizeof(*frame) + 8];
78 struct iwmmxt_sigframe *kframe;
79
80 /* the iWMMXt context must be 64 bit aligned */
81 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
82 if (__copy_from_user(kframe, frame, sizeof(*frame)))
83 return -1;
84 if (kframe->magic != IWMMXT_MAGIC ||
85 kframe->size != IWMMXT_STORAGE_SIZE)
86 return -1;
87 iwmmxt_task_restore(current_thread_info(), &kframe->storage);
88 return 0;
89}
90
91#endif
92
93#ifdef CONFIG_VFP
94
95static int preserve_vfp_context(struct vfp_sigframe __user *frame)
96{
97 const unsigned long magic = VFP_MAGIC;
98 const unsigned long size = VFP_STORAGE_SIZE;
99 int err = 0;
100
101 __put_user_error(magic, &frame->magic, err);
102 __put_user_error(size, &frame->size, err);
103
104 if (err)
105 return -EFAULT;
106
107 return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc);
108}
109
110static int restore_vfp_context(struct vfp_sigframe __user *frame)
111{
112 unsigned long magic;
113 unsigned long size;
114 int err = 0;
115
116 __get_user_error(magic, &frame->magic, err);
117 __get_user_error(size, &frame->size, err);
118
119 if (err)
120 return -EFAULT;
121 if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
122 return -EINVAL;
123
124 return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc);
125}
126
127#endif
128
129/*
130 * Do a signal return; undo the signal stack. These are aligned to 64-bit.
131 */
132struct sigframe {
133 struct ucontext uc;
134 unsigned long retcode[2];
135};
136
137struct rt_sigframe {
138 struct siginfo info;
139 struct sigframe sig;
140};
141
142static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
143{
144 struct aux_sigframe __user *aux;
145 sigset_t set;
146 int err;
147
148 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
149 if (err == 0)
150 set_current_blocked(&set);
151
152 __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
153 __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
154 __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
155 __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
156 __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
157 __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
158 __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
159 __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
160 __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
161 __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
162 __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
163 __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
164 __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
165 __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
166 __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
167 __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
168 __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
169
170 err |= !valid_user_regs(regs);
171
172 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
173#ifdef CONFIG_CRUNCH
174 if (err == 0)
175 err |= restore_crunch_context(&aux->crunch);
176#endif
177#ifdef CONFIG_IWMMXT
178 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
179 err |= restore_iwmmxt_context(&aux->iwmmxt);
180#endif
181#ifdef CONFIG_VFP
182 if (err == 0)
183 err |= restore_vfp_context(&aux->vfp);
184#endif
185
186 return err;
187}
188
189asmlinkage int sys_sigreturn(struct pt_regs *regs)
190{
191 struct sigframe __user *frame;
192
193 /* Always make any pending restarted system calls return -EINTR */
194 current_thread_info()->restart_block.fn = do_no_restart_syscall;
195
196 /*
197 * Since we stacked the signal on a 64-bit boundary,
198 * then 'sp' should be word aligned here. If it's
199 * not, then the user is trying to mess with us.
200 */
201 if (regs->ARM_sp & 7)
202 goto badframe;
203
204 frame = (struct sigframe __user *)regs->ARM_sp;
205
206 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
207 goto badframe;
208
209 if (restore_sigframe(regs, frame))
210 goto badframe;
211
212 return regs->ARM_r0;
213
214badframe:
215 force_sig(SIGSEGV, current);
216 return 0;
217}
218
219asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
220{
221 struct rt_sigframe __user *frame;
222
223 /* Always make any pending restarted system calls return -EINTR */
224 current_thread_info()->restart_block.fn = do_no_restart_syscall;
225
226 /*
227 * Since we stacked the signal on a 64-bit boundary,
228 * then 'sp' should be word aligned here. If it's
229 * not, then the user is trying to mess with us.
230 */
231 if (regs->ARM_sp & 7)
232 goto badframe;
233
234 frame = (struct rt_sigframe __user *)regs->ARM_sp;
235
236 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
237 goto badframe;
238
239 if (restore_sigframe(regs, &frame->sig))
240 goto badframe;
241
242 if (restore_altstack(&frame->sig.uc.uc_stack))
243 goto badframe;
244
245 return regs->ARM_r0;
246
247badframe:
248 force_sig(SIGSEGV, current);
249 return 0;
250}
251
252static int
253setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
254{
255 struct aux_sigframe __user *aux;
256 int err = 0;
257
258 __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
259 __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
260 __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
261 __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
262 __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
263 __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
264 __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
265 __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
266 __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
267 __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
268 __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
269 __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
270 __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
271 __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
272 __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
273 __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
274 __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
275
276 __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err);
277 __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err);
278 __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err);
279 __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
280
281 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
282
283 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
284#ifdef CONFIG_CRUNCH
285 if (err == 0)
286 err |= preserve_crunch_context(&aux->crunch);
287#endif
288#ifdef CONFIG_IWMMXT
289 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
290 err |= preserve_iwmmxt_context(&aux->iwmmxt);
291#endif
292#ifdef CONFIG_VFP
293 if (err == 0)
294 err |= preserve_vfp_context(&aux->vfp);
295#endif
296 __put_user_error(0, &aux->end_magic, err);
297
298 return err;
299}
300
301static inline void __user *
302get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
303{
304 unsigned long sp = sigsp(regs->ARM_sp, ksig);
305 void __user *frame;
306
307 /*
308 * ATPCS B01 mandates 8-byte alignment
309 */
310 frame = (void __user *)((sp - framesize) & ~7);
311
312 /*
313 * Check that we can actually write to the signal frame.
314 */
315 if (!access_ok(VERIFY_WRITE, frame, framesize))
316 frame = NULL;
317
318 return frame;
319}
320
321/*
322 * translate the signal
323 */
324static inline int map_sig(int sig)
325{
326 struct thread_info *thread = current_thread_info();
327 if (sig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
328 sig = thread->exec_domain->signal_invmap[sig];
329 return sig;
330}
331
332static int
333setup_return(struct pt_regs *regs, struct ksignal *ksig,
334 unsigned long __user *rc, void __user *frame)
335{
336 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
337 unsigned long retcode;
338 int thumb = 0;
339 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
340
341 cpsr |= PSR_ENDSTATE;
342
343 /*
344 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
345 */
346 if (ksig->ka.sa.sa_flags & SA_THIRTYTWO)
347 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
348
349#ifdef CONFIG_ARM_THUMB
350 if (elf_hwcap & HWCAP_THUMB) {
351 /*
352 * The LSB of the handler determines if we're going to
353 * be using THUMB or ARM mode for this signal handler.
354 */
355 thumb = handler & 1;
356
357#if __LINUX_ARM_ARCH__ >= 7
358 /*
359 * Clear the If-Then Thumb-2 execution state
360 * ARM spec requires this to be all 000s in ARM mode
361 * Snapdragon S4/Krait misbehaves on a Thumb=>ARM
362 * signal transition without this.
363 */
364 cpsr &= ~PSR_IT_MASK;
365#endif
366
367 if (thumb) {
368 cpsr |= PSR_T_BIT;
369 } else
370 cpsr &= ~PSR_T_BIT;
371 }
372#endif
373
374 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
375 retcode = (unsigned long)ksig->ka.sa.sa_restorer;
376 } else {
377 unsigned int idx = thumb << 1;
378
379 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
380 idx += 3;
381
382 /*
383 * Put the sigreturn code on the stack no matter which return
384 * mechanism we use in order to remain ABI compliant
385 */
386 if (__put_user(sigreturn_codes[idx], rc) ||
387 __put_user(sigreturn_codes[idx+1], rc+1))
388 return 1;
389
390#ifdef CONFIG_MMU
391 if (cpsr & MODE32_BIT) {
392 struct mm_struct *mm = current->mm;
393
394 /*
395 * 32-bit code can use the signal return page
396 * except when the MPU has protected the vectors
397 * page from PL0
398 */
399 retcode = mm->context.sigpage + signal_return_offset +
400 (idx << 2) + thumb;
401 } else
402#endif
403 {
404 /*
405 * Ensure that the instruction cache sees
406 * the return code written onto the stack.
407 */
408 flush_icache_range((unsigned long)rc,
409 (unsigned long)(rc + 2));
410
411 retcode = ((unsigned long)rc) + thumb;
412 }
413 }
414
415 regs->ARM_r0 = map_sig(ksig->sig);
416 regs->ARM_sp = (unsigned long)frame;
417 regs->ARM_lr = retcode;
418 regs->ARM_pc = handler;
419 regs->ARM_cpsr = cpsr;
420
421 return 0;
422}
423
424static int
425setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
426{
427 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
428 int err = 0;
429
430 if (!frame)
431 return 1;
432
433 /*
434 * Set uc.uc_flags to a value which sc.trap_no would never have.
435 */
436 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
437
438 err |= setup_sigframe(frame, regs, set);
439 if (err == 0)
440 err = setup_return(regs, ksig, frame->retcode, frame);
441
442 return err;
443}
444
445static int
446setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
447{
448 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
449 int err = 0;
450
451 if (!frame)
452 return 1;
453
454 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
455
456 __put_user_error(0, &frame->sig.uc.uc_flags, err);
457 __put_user_error(NULL, &frame->sig.uc.uc_link, err);
458
459 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp);
460 err |= setup_sigframe(&frame->sig, regs, set);
461 if (err == 0)
462 err = setup_return(regs, ksig, frame->sig.retcode, frame);
463
464 if (err == 0) {
465 /*
466 * For realtime signals we must also set the second and third
467 * arguments for the signal handler.
468 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
469 */
470 regs->ARM_r1 = (unsigned long)&frame->info;
471 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
472 }
473
474 return err;
475}
476
477/*
478 * OK, we're invoking a handler
479 */
480static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
481{
482 sigset_t *oldset = sigmask_to_save();
483 int ret;
484
485 /*
486 * Set up the stack frame
487 */
488 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
489 ret = setup_rt_frame(ksig, oldset, regs);
490 else
491 ret = setup_frame(ksig, oldset, regs);
492
493 /*
494 * Check that the resulting registers are actually sane.
495 */
496 ret |= !valid_user_regs(regs);
497
498 signal_setup_done(ret, ksig, 0);
499}
500
501/*
502 * Note that 'init' is a special process: it doesn't get signals it doesn't
503 * want to handle. Thus you cannot kill init even with a SIGKILL even by
504 * mistake.
505 *
506 * Note that we go through the signals twice: once to check the signals that
507 * the kernel can handle, and then we build all the user-level signal handling
508 * stack-frames in one go after that.
509 */
510static int do_signal(struct pt_regs *regs, int syscall)
511{
512 unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
513 struct ksignal ksig;
514 int restart = 0;
515
516 /*
517 * If we were from a system call, check for system call restarting...
518 */
519 if (syscall) {
520 continue_addr = regs->ARM_pc;
521 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
522 retval = regs->ARM_r0;
523
524 /*
525 * Prepare for system call restart. We do this here so that a
526 * debugger will see the already changed PSW.
527 */
528 switch (retval) {
529 case -ERESTART_RESTARTBLOCK:
530 restart -= 2;
531 case -ERESTARTNOHAND:
532 case -ERESTARTSYS:
533 case -ERESTARTNOINTR:
534 restart++;
535 regs->ARM_r0 = regs->ARM_ORIG_r0;
536 regs->ARM_pc = restart_addr;
537 break;
538 }
539 }
540
541 /*
542 * Get the signal to deliver. When running under ptrace, at this
543 * point the debugger may change all our registers ...
544 */
545 /*
546 * Depending on the signal settings we may need to revert the
547 * decision to restart the system call. But skip this if a
548 * debugger has chosen to restart at a different PC.
549 */
550 if (get_signal(&ksig)) {
551 /* handler */
552 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
553 if (retval == -ERESTARTNOHAND ||
554 retval == -ERESTART_RESTARTBLOCK
555 || (retval == -ERESTARTSYS
556 && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
557 regs->ARM_r0 = -EINTR;
558 regs->ARM_pc = continue_addr;
559 }
560 }
561 handle_signal(&ksig, regs);
562 } else {
563 /* no handler */
564 restore_saved_sigmask();
565 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
566 regs->ARM_pc = continue_addr;
567 return restart;
568 }
569 }
570 return 0;
571}
572
573asmlinkage int
574do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
575{
576 do {
577 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
578 schedule();
579 } else {
580 if (unlikely(!user_mode(regs)))
581 return 0;
582 local_irq_enable();
583 if (thread_flags & _TIF_SIGPENDING) {
584 int restart = do_signal(regs, syscall);
585 if (unlikely(restart)) {
586 /*
587 * Restart without handlers.
588 * Deal with it without leaving
589 * the kernel space.
590 */
591 return restart;
592 }
593 syscall = 0;
594 } else if (thread_flags & _TIF_UPROBE) {
595 clear_thread_flag(TIF_UPROBE);
596 uprobe_notify_resume(regs);
597 } else {
598 clear_thread_flag(TIF_NOTIFY_RESUME);
599 tracehook_notify_resume(regs);
600 }
601 }
602 local_irq_disable();
603 thread_flags = current_thread_info()->flags;
604 } while (thread_flags & _TIF_WORK_MASK);
605 return 0;
606}
607
608struct page *get_signal_page(void)
609{
610 unsigned long ptr;
611 unsigned offset;
612 struct page *page;
613 void *addr;
614
615 page = alloc_pages(GFP_KERNEL, 0);
616
617 if (!page)
618 return NULL;
619
620 addr = page_address(page);
621
622 /* Give the signal return code some randomness */
623 offset = 0x200 + (get_random_int() & 0x7fc);
624 signal_return_offset = offset;
625
626 /*
627 * Copy signal return handlers into the vector page, and
628 * set sigreturn to be a pointer to these.
629 */
630 memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
631
632 ptr = (unsigned long)addr + offset;
633 flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
634
635 return page;
636}