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