7b8f2141427bda172899bfe8ae5113367163af47
[deliverable/linux.git] / arch / arm / kernel / signal.c
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
25 extern const unsigned long sigreturn_codes[7];
26
27 static unsigned long signal_return_offset;
28
29 #ifdef CONFIG_CRUNCH
30 static 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
43 static 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
62 static 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
75 static 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
95 static 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
110 static 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 */
132 struct sigframe {
133 struct ucontext uc;
134 unsigned long retcode[2];
135 };
136
137 struct rt_sigframe {
138 struct siginfo info;
139 struct sigframe sig;
140 };
141
142 static 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
189 asmlinkage 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->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
214 badframe:
215 force_sig(SIGSEGV, current);
216 return 0;
217 }
218
219 asmlinkage 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->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
247 badframe:
248 force_sig(SIGSEGV, current);
249 return 0;
250 }
251
252 static int
253 setup_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
301 static inline void __user *
302 get_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 static int
322 setup_return(struct pt_regs *regs, struct ksignal *ksig,
323 unsigned long __user *rc, void __user *frame)
324 {
325 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
326 unsigned long retcode;
327 int thumb = 0;
328 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
329
330 cpsr |= PSR_ENDSTATE;
331
332 /*
333 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
334 */
335 if (ksig->ka.sa.sa_flags & SA_THIRTYTWO)
336 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
337
338 #ifdef CONFIG_ARM_THUMB
339 if (elf_hwcap & HWCAP_THUMB) {
340 /*
341 * The LSB of the handler determines if we're going to
342 * be using THUMB or ARM mode for this signal handler.
343 */
344 thumb = handler & 1;
345
346 /*
347 * Clear the If-Then Thumb-2 execution state. ARM spec
348 * requires this to be all 000s in ARM mode. Snapdragon
349 * S4/Krait misbehaves on a Thumb=>ARM signal transition
350 * without this.
351 *
352 * We must do this whenever we are running on a Thumb-2
353 * capable CPU, which includes ARMv6T2. However, we elect
354 * to always do this to simplify the code; this field is
355 * marked UNK/SBZP for older architectures.
356 */
357 cpsr &= ~PSR_IT_MASK;
358
359 if (thumb) {
360 cpsr |= PSR_T_BIT;
361 } else
362 cpsr &= ~PSR_T_BIT;
363 }
364 #endif
365
366 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
367 retcode = (unsigned long)ksig->ka.sa.sa_restorer;
368 } else {
369 unsigned int idx = thumb << 1;
370
371 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
372 idx += 3;
373
374 /*
375 * Put the sigreturn code on the stack no matter which return
376 * mechanism we use in order to remain ABI compliant
377 */
378 if (__put_user(sigreturn_codes[idx], rc) ||
379 __put_user(sigreturn_codes[idx+1], rc+1))
380 return 1;
381
382 #ifdef CONFIG_MMU
383 if (cpsr & MODE32_BIT) {
384 struct mm_struct *mm = current->mm;
385
386 /*
387 * 32-bit code can use the signal return page
388 * except when the MPU has protected the vectors
389 * page from PL0
390 */
391 retcode = mm->context.sigpage + signal_return_offset +
392 (idx << 2) + thumb;
393 } else
394 #endif
395 {
396 /*
397 * Ensure that the instruction cache sees
398 * the return code written onto the stack.
399 */
400 flush_icache_range((unsigned long)rc,
401 (unsigned long)(rc + 2));
402
403 retcode = ((unsigned long)rc) + thumb;
404 }
405 }
406
407 regs->ARM_r0 = ksig->sig;
408 regs->ARM_sp = (unsigned long)frame;
409 regs->ARM_lr = retcode;
410 regs->ARM_pc = handler;
411 regs->ARM_cpsr = cpsr;
412
413 return 0;
414 }
415
416 static int
417 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
418 {
419 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
420 int err = 0;
421
422 if (!frame)
423 return 1;
424
425 /*
426 * Set uc.uc_flags to a value which sc.trap_no would never have.
427 */
428 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
429
430 err |= setup_sigframe(frame, regs, set);
431 if (err == 0)
432 err = setup_return(regs, ksig, frame->retcode, frame);
433
434 return err;
435 }
436
437 static int
438 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
439 {
440 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
441 int err = 0;
442
443 if (!frame)
444 return 1;
445
446 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
447
448 __put_user_error(0, &frame->sig.uc.uc_flags, err);
449 __put_user_error(NULL, &frame->sig.uc.uc_link, err);
450
451 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp);
452 err |= setup_sigframe(&frame->sig, regs, set);
453 if (err == 0)
454 err = setup_return(regs, ksig, frame->sig.retcode, frame);
455
456 if (err == 0) {
457 /*
458 * For realtime signals we must also set the second and third
459 * arguments for the signal handler.
460 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
461 */
462 regs->ARM_r1 = (unsigned long)&frame->info;
463 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
464 }
465
466 return err;
467 }
468
469 /*
470 * OK, we're invoking a handler
471 */
472 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
473 {
474 sigset_t *oldset = sigmask_to_save();
475 int ret;
476
477 /*
478 * Set up the stack frame
479 */
480 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
481 ret = setup_rt_frame(ksig, oldset, regs);
482 else
483 ret = setup_frame(ksig, oldset, regs);
484
485 /*
486 * Check that the resulting registers are actually sane.
487 */
488 ret |= !valid_user_regs(regs);
489
490 signal_setup_done(ret, ksig, 0);
491 }
492
493 /*
494 * Note that 'init' is a special process: it doesn't get signals it doesn't
495 * want to handle. Thus you cannot kill init even with a SIGKILL even by
496 * mistake.
497 *
498 * Note that we go through the signals twice: once to check the signals that
499 * the kernel can handle, and then we build all the user-level signal handling
500 * stack-frames in one go after that.
501 */
502 static int do_signal(struct pt_regs *regs, int syscall)
503 {
504 unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
505 struct ksignal ksig;
506 int restart = 0;
507
508 /*
509 * If we were from a system call, check for system call restarting...
510 */
511 if (syscall) {
512 continue_addr = regs->ARM_pc;
513 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
514 retval = regs->ARM_r0;
515
516 /*
517 * Prepare for system call restart. We do this here so that a
518 * debugger will see the already changed PSW.
519 */
520 switch (retval) {
521 case -ERESTART_RESTARTBLOCK:
522 restart -= 2;
523 case -ERESTARTNOHAND:
524 case -ERESTARTSYS:
525 case -ERESTARTNOINTR:
526 restart++;
527 regs->ARM_r0 = regs->ARM_ORIG_r0;
528 regs->ARM_pc = restart_addr;
529 break;
530 }
531 }
532
533 /*
534 * Get the signal to deliver. When running under ptrace, at this
535 * point the debugger may change all our registers ...
536 */
537 /*
538 * Depending on the signal settings we may need to revert the
539 * decision to restart the system call. But skip this if a
540 * debugger has chosen to restart at a different PC.
541 */
542 if (get_signal(&ksig)) {
543 /* handler */
544 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
545 if (retval == -ERESTARTNOHAND ||
546 retval == -ERESTART_RESTARTBLOCK
547 || (retval == -ERESTARTSYS
548 && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
549 regs->ARM_r0 = -EINTR;
550 regs->ARM_pc = continue_addr;
551 }
552 }
553 handle_signal(&ksig, regs);
554 } else {
555 /* no handler */
556 restore_saved_sigmask();
557 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
558 regs->ARM_pc = continue_addr;
559 return restart;
560 }
561 }
562 return 0;
563 }
564
565 asmlinkage int
566 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
567 {
568 /*
569 * The assembly code enters us with IRQs off, but it hasn't
570 * informed the tracing code of that for efficiency reasons.
571 * Update the trace code with the current status.
572 */
573 trace_hardirqs_off();
574 do {
575 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
576 schedule();
577 } else {
578 if (unlikely(!user_mode(regs)))
579 return 0;
580 local_irq_enable();
581 if (thread_flags & _TIF_SIGPENDING) {
582 int restart = do_signal(regs, syscall);
583 if (unlikely(restart)) {
584 /*
585 * Restart without handlers.
586 * Deal with it without leaving
587 * the kernel space.
588 */
589 return restart;
590 }
591 syscall = 0;
592 } else if (thread_flags & _TIF_UPROBE) {
593 uprobe_notify_resume(regs);
594 } else {
595 clear_thread_flag(TIF_NOTIFY_RESUME);
596 tracehook_notify_resume(regs);
597 }
598 }
599 local_irq_disable();
600 thread_flags = current_thread_info()->flags;
601 } while (thread_flags & _TIF_WORK_MASK);
602 return 0;
603 }
604
605 struct page *get_signal_page(void)
606 {
607 unsigned long ptr;
608 unsigned offset;
609 struct page *page;
610 void *addr;
611
612 page = alloc_pages(GFP_KERNEL, 0);
613
614 if (!page)
615 return NULL;
616
617 addr = page_address(page);
618
619 /* Give the signal return code some randomness */
620 offset = 0x200 + (get_random_int() & 0x7fc);
621 signal_return_offset = offset;
622
623 /*
624 * Copy signal return handlers into the vector page, and
625 * set sigreturn to be a pointer to these.
626 */
627 memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
628
629 ptr = (unsigned long)addr + offset;
630 flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
631
632 return page;
633 }
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