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/signal.h>
12 #include <linux/personality.h>
13 #include <linux/freezer.h>
14 #include <linux/uaccess.h>
15 #include <linux/tracehook.h>
16
17 #include <asm/elf.h>
18 #include <asm/cacheflush.h>
19 #include <asm/ucontext.h>
20 #include <asm/unistd.h>
21 #include <asm/vfp.h>
22
23 #include "signal.h"
24
25 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
26
27 /*
28 * For ARM syscalls, we encode the syscall number into the instruction.
29 */
30 #define SWI_SYS_SIGRETURN (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
31 #define SWI_SYS_RT_SIGRETURN (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
32
33 /*
34 * With EABI, the syscall number has to be loaded into r7.
35 */
36 #define MOV_R7_NR_SIGRETURN (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE))
37 #define MOV_R7_NR_RT_SIGRETURN (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
38
39 /*
40 * For Thumb syscalls, we pass the syscall number via r7. We therefore
41 * need two 16-bit instructions.
42 */
43 #define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
44 #define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
45
46 const unsigned long sigreturn_codes[7] = {
47 MOV_R7_NR_SIGRETURN, SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN,
48 MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
49 };
50
51 /*
52 * atomically swap in the new signal mask, and wait for a signal.
53 */
sys_sigsuspend(int restart,unsigned long oldmask,old_sigset_t mask)54 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask)
55 {
56 sigset_t blocked;
57
58 current->saved_sigmask = current->blocked;
59
60 mask &= _BLOCKABLE;
61 siginitset(&blocked, mask);
62 set_current_blocked(&blocked);
63
64 current->state = TASK_INTERRUPTIBLE;
65 schedule();
66 set_restore_sigmask();
67 return -ERESTARTNOHAND;
68 }
69
70 asmlinkage int
sys_sigaction(int sig,const struct old_sigaction __user * act,struct old_sigaction __user * oact)71 sys_sigaction(int sig, const struct old_sigaction __user *act,
72 struct old_sigaction __user *oact)
73 {
74 struct k_sigaction new_ka, old_ka;
75 int ret;
76
77 if (act) {
78 old_sigset_t mask;
79 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
80 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
81 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
82 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
83 __get_user(mask, &act->sa_mask))
84 return -EFAULT;
85 siginitset(&new_ka.sa.sa_mask, mask);
86 }
87
88 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
89
90 if (!ret && oact) {
91 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
92 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
93 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
94 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
95 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
96 return -EFAULT;
97 }
98
99 return ret;
100 }
101
102 #ifdef CONFIG_CRUNCH
preserve_crunch_context(struct crunch_sigframe __user * frame)103 static int preserve_crunch_context(struct crunch_sigframe __user *frame)
104 {
105 char kbuf[sizeof(*frame) + 8];
106 struct crunch_sigframe *kframe;
107
108 /* the crunch context must be 64 bit aligned */
109 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
110 kframe->magic = CRUNCH_MAGIC;
111 kframe->size = CRUNCH_STORAGE_SIZE;
112 crunch_task_copy(current_thread_info(), &kframe->storage);
113 return __copy_to_user(frame, kframe, sizeof(*frame));
114 }
115
restore_crunch_context(struct crunch_sigframe __user * frame)116 static int restore_crunch_context(struct crunch_sigframe __user *frame)
117 {
118 char kbuf[sizeof(*frame) + 8];
119 struct crunch_sigframe *kframe;
120
121 /* the crunch context must be 64 bit aligned */
122 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
123 if (__copy_from_user(kframe, frame, sizeof(*frame)))
124 return -1;
125 if (kframe->magic != CRUNCH_MAGIC ||
126 kframe->size != CRUNCH_STORAGE_SIZE)
127 return -1;
128 crunch_task_restore(current_thread_info(), &kframe->storage);
129 return 0;
130 }
131 #endif
132
133 #ifdef CONFIG_IWMMXT
134
preserve_iwmmxt_context(struct iwmmxt_sigframe * frame)135 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
136 {
137 char kbuf[sizeof(*frame) + 8];
138 struct iwmmxt_sigframe *kframe;
139
140 /* the iWMMXt context must be 64 bit aligned */
141 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
142 kframe->magic = IWMMXT_MAGIC;
143 kframe->size = IWMMXT_STORAGE_SIZE;
144 iwmmxt_task_copy(current_thread_info(), &kframe->storage);
145 return __copy_to_user(frame, kframe, sizeof(*frame));
146 }
147
restore_iwmmxt_context(struct iwmmxt_sigframe * frame)148 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
149 {
150 char kbuf[sizeof(*frame) + 8];
151 struct iwmmxt_sigframe *kframe;
152
153 /* the iWMMXt context must be 64 bit aligned */
154 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
155 if (__copy_from_user(kframe, frame, sizeof(*frame)))
156 return -1;
157 if (kframe->magic != IWMMXT_MAGIC ||
158 kframe->size != IWMMXT_STORAGE_SIZE)
159 return -1;
160 iwmmxt_task_restore(current_thread_info(), &kframe->storage);
161 return 0;
162 }
163
164 #endif
165
166 #ifdef CONFIG_VFP
167
preserve_vfp_context(struct vfp_sigframe __user * frame)168 static int preserve_vfp_context(struct vfp_sigframe __user *frame)
169 {
170 const unsigned long magic = VFP_MAGIC;
171 const unsigned long size = VFP_STORAGE_SIZE;
172 int err = 0;
173
174 __put_user_error(magic, &frame->magic, err);
175 __put_user_error(size, &frame->size, err);
176
177 if (err)
178 return -EFAULT;
179
180 return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc);
181 }
182
restore_vfp_context(struct vfp_sigframe __user * frame)183 static int restore_vfp_context(struct vfp_sigframe __user *frame)
184 {
185 unsigned long magic;
186 unsigned long size;
187 int err = 0;
188
189 __get_user_error(magic, &frame->magic, err);
190 __get_user_error(size, &frame->size, err);
191
192 if (err)
193 return -EFAULT;
194 if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
195 return -EINVAL;
196
197 return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc);
198 }
199
200 #endif
201
202 /*
203 * Do a signal return; undo the signal stack. These are aligned to 64-bit.
204 */
205 struct sigframe {
206 struct ucontext uc;
207 unsigned long retcode[2];
208 };
209
210 struct rt_sigframe {
211 struct siginfo info;
212 struct sigframe sig;
213 };
214
restore_sigframe(struct pt_regs * regs,struct sigframe __user * sf)215 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
216 {
217 struct aux_sigframe __user *aux;
218 sigset_t set;
219 int err;
220
221 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
222 if (err == 0) {
223 sigdelsetmask(&set, ~_BLOCKABLE);
224 set_current_blocked(&set);
225 }
226
227 __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
228 __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
229 __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
230 __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
231 __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
232 __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
233 __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
234 __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
235 __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
236 __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
237 __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
238 __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
239 __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
240 __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
241 __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
242 __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
243 __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
244
245 err |= !valid_user_regs(regs);
246
247 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
248 #ifdef CONFIG_CRUNCH
249 if (err == 0)
250 err |= restore_crunch_context(&aux->crunch);
251 #endif
252 #ifdef CONFIG_IWMMXT
253 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
254 err |= restore_iwmmxt_context(&aux->iwmmxt);
255 #endif
256 #ifdef CONFIG_VFP
257 if (err == 0)
258 err |= restore_vfp_context(&aux->vfp);
259 #endif
260
261 return err;
262 }
263
sys_sigreturn(struct pt_regs * regs)264 asmlinkage int sys_sigreturn(struct pt_regs *regs)
265 {
266 struct sigframe __user *frame;
267
268 /* Always make any pending restarted system calls return -EINTR */
269 current_thread_info()->restart_block.fn = do_no_restart_syscall;
270
271 /*
272 * Since we stacked the signal on a 64-bit boundary,
273 * then 'sp' should be word aligned here. If it's
274 * not, then the user is trying to mess with us.
275 */
276 if (regs->ARM_sp & 7)
277 goto badframe;
278
279 frame = (struct sigframe __user *)regs->ARM_sp;
280
281 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
282 goto badframe;
283
284 if (restore_sigframe(regs, frame))
285 goto badframe;
286
287 return regs->ARM_r0;
288
289 badframe:
290 force_sig(SIGSEGV, current);
291 return 0;
292 }
293
sys_rt_sigreturn(struct pt_regs * regs)294 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
295 {
296 struct rt_sigframe __user *frame;
297
298 /* Always make any pending restarted system calls return -EINTR */
299 current_thread_info()->restart_block.fn = do_no_restart_syscall;
300
301 /*
302 * Since we stacked the signal on a 64-bit boundary,
303 * then 'sp' should be word aligned here. If it's
304 * not, then the user is trying to mess with us.
305 */
306 if (regs->ARM_sp & 7)
307 goto badframe;
308
309 frame = (struct rt_sigframe __user *)regs->ARM_sp;
310
311 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
312 goto badframe;
313
314 if (restore_sigframe(regs, &frame->sig))
315 goto badframe;
316
317 if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
318 goto badframe;
319
320 return regs->ARM_r0;
321
322 badframe:
323 force_sig(SIGSEGV, current);
324 return 0;
325 }
326
327 static int
setup_sigframe(struct sigframe __user * sf,struct pt_regs * regs,sigset_t * set)328 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
329 {
330 struct aux_sigframe __user *aux;
331 int err = 0;
332
333 __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
334 __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
335 __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
336 __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
337 __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
338 __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
339 __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
340 __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
341 __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
342 __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
343 __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
344 __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
345 __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
346 __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
347 __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
348 __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
349 __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
350
351 __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err);
352 __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err);
353 __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err);
354 __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
355
356 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
357
358 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
359 #ifdef CONFIG_CRUNCH
360 if (err == 0)
361 err |= preserve_crunch_context(&aux->crunch);
362 #endif
363 #ifdef CONFIG_IWMMXT
364 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
365 err |= preserve_iwmmxt_context(&aux->iwmmxt);
366 #endif
367 #ifdef CONFIG_VFP
368 if (err == 0)
369 err |= preserve_vfp_context(&aux->vfp);
370 #endif
371 __put_user_error(0, &aux->end_magic, err);
372
373 return err;
374 }
375
376 static inline void __user *
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,int framesize)377 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
378 {
379 unsigned long sp = regs->ARM_sp;
380 void __user *frame;
381
382 /*
383 * This is the X/Open sanctioned signal stack switching.
384 */
385 if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
386 sp = current->sas_ss_sp + current->sas_ss_size;
387
388 /*
389 * ATPCS B01 mandates 8-byte alignment
390 */
391 frame = (void __user *)((sp - framesize) & ~7);
392
393 /*
394 * Check that we can actually write to the signal frame.
395 */
396 if (!access_ok(VERIFY_WRITE, frame, framesize))
397 frame = NULL;
398
399 return frame;
400 }
401
402 static int
setup_return(struct pt_regs * regs,struct k_sigaction * ka,unsigned long __user * rc,void __user * frame,int usig)403 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
404 unsigned long __user *rc, void __user *frame, int usig)
405 {
406 unsigned long handler = (unsigned long)ka->sa.sa_handler;
407 unsigned long retcode;
408 int thumb = 0;
409 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
410
411 cpsr |= PSR_ENDSTATE;
412
413 /*
414 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
415 */
416 if (ka->sa.sa_flags & SA_THIRTYTWO)
417 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
418
419 #ifdef CONFIG_ARM_THUMB
420 if (elf_hwcap & HWCAP_THUMB) {
421 /*
422 * The LSB of the handler determines if we're going to
423 * be using THUMB or ARM mode for this signal handler.
424 */
425 thumb = handler & 1;
426
427 if (thumb) {
428 cpsr |= PSR_T_BIT;
429 #if __LINUX_ARM_ARCH__ >= 7
430 /* clear the If-Then Thumb-2 execution state */
431 cpsr &= ~PSR_IT_MASK;
432 #endif
433 } else
434 cpsr &= ~PSR_T_BIT;
435 }
436 #endif
437
438 if (ka->sa.sa_flags & SA_RESTORER) {
439 retcode = (unsigned long)ka->sa.sa_restorer;
440 } else {
441 unsigned int idx = thumb << 1;
442
443 if (ka->sa.sa_flags & SA_SIGINFO)
444 idx += 3;
445
446 if (__put_user(sigreturn_codes[idx], rc) ||
447 __put_user(sigreturn_codes[idx+1], rc+1))
448 return 1;
449
450 if (cpsr & MODE32_BIT) {
451 /*
452 * 32-bit code can use the new high-page
453 * signal return code support.
454 */
455 retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb;
456 } else {
457 /*
458 * Ensure that the instruction cache sees
459 * the return code written onto the stack.
460 */
461 flush_icache_range((unsigned long)rc,
462 (unsigned long)(rc + 2));
463
464 retcode = ((unsigned long)rc) + thumb;
465 }
466 }
467
468 regs->ARM_r0 = usig;
469 regs->ARM_sp = (unsigned long)frame;
470 regs->ARM_lr = retcode;
471 regs->ARM_pc = handler;
472 regs->ARM_cpsr = cpsr;
473
474 return 0;
475 }
476
477 static int
setup_frame(int usig,struct k_sigaction * ka,sigset_t * set,struct pt_regs * regs)478 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
479 {
480 struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
481 int err = 0;
482
483 if (!frame)
484 return 1;
485
486 /*
487 * Set uc.uc_flags to a value which sc.trap_no would never have.
488 */
489 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
490
491 err |= setup_sigframe(frame, regs, set);
492 if (err == 0)
493 err = setup_return(regs, ka, frame->retcode, frame, usig);
494
495 return err;
496 }
497
498 static int
setup_rt_frame(int usig,struct k_sigaction * ka,siginfo_t * info,sigset_t * set,struct pt_regs * regs)499 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
500 sigset_t *set, struct pt_regs *regs)
501 {
502 struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
503 stack_t stack;
504 int err = 0;
505
506 if (!frame)
507 return 1;
508
509 err |= copy_siginfo_to_user(&frame->info, info);
510
511 __put_user_error(0, &frame->sig.uc.uc_flags, err);
512 __put_user_error(NULL, &frame->sig.uc.uc_link, err);
513
514 memset(&stack, 0, sizeof(stack));
515 stack.ss_sp = (void __user *)current->sas_ss_sp;
516 stack.ss_flags = sas_ss_flags(regs->ARM_sp);
517 stack.ss_size = current->sas_ss_size;
518 err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
519
520 err |= setup_sigframe(&frame->sig, regs, set);
521 if (err == 0)
522 err = setup_return(regs, ka, frame->sig.retcode, frame, usig);
523
524 if (err == 0) {
525 /*
526 * For realtime signals we must also set the second and third
527 * arguments for the signal handler.
528 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
529 */
530 regs->ARM_r1 = (unsigned long)&frame->info;
531 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
532 }
533
534 return err;
535 }
536
537 /*
538 * OK, we're invoking a handler
539 */
540 static int
handle_signal(unsigned long sig,struct k_sigaction * ka,siginfo_t * info,sigset_t * oldset,struct pt_regs * regs)541 handle_signal(unsigned long sig, struct k_sigaction *ka,
542 siginfo_t *info, sigset_t *oldset,
543 struct pt_regs * regs)
544 {
545 struct thread_info *thread = current_thread_info();
546 struct task_struct *tsk = current;
547 int usig = sig;
548 int ret;
549
550 /*
551 * translate the signal
552 */
553 if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
554 usig = thread->exec_domain->signal_invmap[usig];
555
556 /*
557 * Set up the stack frame
558 */
559 if (ka->sa.sa_flags & SA_SIGINFO)
560 ret = setup_rt_frame(usig, ka, info, oldset, regs);
561 else
562 ret = setup_frame(usig, ka, oldset, regs);
563
564 /*
565 * Check that the resulting registers are actually sane.
566 */
567 ret |= !valid_user_regs(regs);
568
569 if (ret != 0) {
570 force_sigsegv(sig, tsk);
571 return ret;
572 }
573
574 /*
575 * Block the signal if we were successful.
576 */
577 block_sigmask(ka, sig);
578
579 return 0;
580 }
581
582 /*
583 * Note that 'init' is a special process: it doesn't get signals it doesn't
584 * want to handle. Thus you cannot kill init even with a SIGKILL even by
585 * mistake.
586 *
587 * Note that we go through the signals twice: once to check the signals that
588 * the kernel can handle, and then we build all the user-level signal handling
589 * stack-frames in one go after that.
590 */
do_signal(struct pt_regs * regs,int syscall)591 static int do_signal(struct pt_regs *regs, int syscall)
592 {
593 unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
594 struct k_sigaction ka;
595 siginfo_t info;
596 int signr;
597 int restart = 0;
598
599 /*
600 * If we were from a system call, check for system call restarting...
601 */
602 if (syscall) {
603 continue_addr = regs->ARM_pc;
604 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
605 retval = regs->ARM_r0;
606
607 /*
608 * Prepare for system call restart. We do this here so that a
609 * debugger will see the already changed PSW.
610 */
611 switch (retval) {
612 case -ERESTART_RESTARTBLOCK:
613 restart -= 2;
614 case -ERESTARTNOHAND:
615 case -ERESTARTSYS:
616 case -ERESTARTNOINTR:
617 restart++;
618 regs->ARM_r0 = regs->ARM_ORIG_r0;
619 regs->ARM_pc = restart_addr;
620 break;
621 }
622 }
623
624 /*
625 * Get the signal to deliver. When running under ptrace, at this
626 * point the debugger may change all our registers ...
627 */
628 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
629 /*
630 * Depending on the signal settings we may need to revert the
631 * decision to restart the system call. But skip this if a
632 * debugger has chosen to restart at a different PC.
633 */
634 if (regs->ARM_pc != restart_addr)
635 restart = 0;
636 if (signr > 0) {
637 sigset_t *oldset;
638
639 if (unlikely(restart)) {
640 if (retval == -ERESTARTNOHAND ||
641 retval == -ERESTART_RESTARTBLOCK
642 || (retval == -ERESTARTSYS
643 && !(ka.sa.sa_flags & SA_RESTART))) {
644 regs->ARM_r0 = -EINTR;
645 regs->ARM_pc = continue_addr;
646 }
647 }
648
649 if (test_thread_flag(TIF_RESTORE_SIGMASK))
650 oldset = ¤t->saved_sigmask;
651 else
652 oldset = ¤t->blocked;
653 if (handle_signal(signr, &ka, &info, oldset, regs) == 0) {
654 /*
655 * A signal was successfully delivered; the saved
656 * sigmask will have been stored in the signal frame,
657 * and will be restored by sigreturn, so we can simply
658 * clear the TIF_RESTORE_SIGMASK flag.
659 */
660 if (test_thread_flag(TIF_RESTORE_SIGMASK))
661 clear_thread_flag(TIF_RESTORE_SIGMASK);
662 }
663 return 0;
664 }
665
666 /* If there's no signal to deliver, we just put the saved sigmask
667 * back.
668 */
669 if (test_and_clear_thread_flag(TIF_RESTORE_SIGMASK))
670 set_current_blocked(¤t->saved_sigmask);
671 if (unlikely(restart))
672 regs->ARM_pc = continue_addr;
673 return restart;
674 }
675
676 asmlinkage int
do_work_pending(struct pt_regs * regs,unsigned int thread_flags,int syscall)677 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
678 {
679 do {
680 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
681 schedule();
682 } else {
683 if (unlikely(!user_mode(regs)))
684 return 0;
685 local_irq_enable();
686 if (thread_flags & _TIF_SIGPENDING) {
687 int restart = do_signal(regs, syscall);
688 if (unlikely(restart)) {
689 /*
690 * Restart without handlers.
691 * Deal with it without leaving
692 * the kernel space.
693 */
694 return restart;
695 }
696 syscall = 0;
697 } else {
698 clear_thread_flag(TIF_NOTIFY_RESUME);
699 tracehook_notify_resume(regs);
700 if (current->replacement_session_keyring)
701 key_replace_session_keyring();
702 }
703 }
704 local_irq_disable();
705 thread_flags = current_thread_info()->flags;
706 } while (thread_flags & _TIF_WORK_MASK);
707 return 0;
708 }
709