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
17 #include <asm/elf.h>
18 #include <asm/cacheflush.h>
19 #include <asm/traps.h>
20 #include <asm/ucontext.h>
21 #include <asm/unistd.h>
22 #include <asm/vfp.h>
23
24 /*
25 * For ARM syscalls, we encode the syscall number into the instruction.
26 */
27 #define SWI_SYS_SIGRETURN (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
28 #define SWI_SYS_RT_SIGRETURN (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
29
30 /*
31 * With EABI, the syscall number has to be loaded into r7.
32 */
33 #define MOV_R7_NR_SIGRETURN (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE))
34 #define MOV_R7_NR_RT_SIGRETURN (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
35
36 /*
37 * For Thumb syscalls, we pass the syscall number via r7. We therefore
38 * need two 16-bit instructions.
39 */
40 #define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
41 #define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
42
43 static const unsigned long sigreturn_codes[7] = {
44 MOV_R7_NR_SIGRETURN, SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN,
45 MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
46 };
47
48 static unsigned long signal_return_offset;
49
50 #ifdef CONFIG_CRUNCH
preserve_crunch_context(struct crunch_sigframe __user * frame)51 static int preserve_crunch_context(struct crunch_sigframe __user *frame)
52 {
53 char kbuf[sizeof(*frame) + 8];
54 struct crunch_sigframe *kframe;
55
56 /* the crunch context must be 64 bit aligned */
57 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
58 kframe->magic = CRUNCH_MAGIC;
59 kframe->size = CRUNCH_STORAGE_SIZE;
60 crunch_task_copy(current_thread_info(), &kframe->storage);
61 return __copy_to_user(frame, kframe, sizeof(*frame));
62 }
63
restore_crunch_context(struct crunch_sigframe __user * frame)64 static int restore_crunch_context(struct crunch_sigframe __user *frame)
65 {
66 char kbuf[sizeof(*frame) + 8];
67 struct crunch_sigframe *kframe;
68
69 /* the crunch context must be 64 bit aligned */
70 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
71 if (__copy_from_user(kframe, frame, sizeof(*frame)))
72 return -1;
73 if (kframe->magic != CRUNCH_MAGIC ||
74 kframe->size != CRUNCH_STORAGE_SIZE)
75 return -1;
76 crunch_task_restore(current_thread_info(), &kframe->storage);
77 return 0;
78 }
79 #endif
80
81 #ifdef CONFIG_IWMMXT
82
preserve_iwmmxt_context(struct iwmmxt_sigframe * frame)83 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
84 {
85 char kbuf[sizeof(*frame) + 8];
86 struct iwmmxt_sigframe *kframe;
87
88 /* the iWMMXt context must be 64 bit aligned */
89 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
90 kframe->magic = IWMMXT_MAGIC;
91 kframe->size = IWMMXT_STORAGE_SIZE;
92 iwmmxt_task_copy(current_thread_info(), &kframe->storage);
93 return __copy_to_user(frame, kframe, sizeof(*frame));
94 }
95
restore_iwmmxt_context(struct iwmmxt_sigframe * frame)96 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
97 {
98 char kbuf[sizeof(*frame) + 8];
99 struct iwmmxt_sigframe *kframe;
100
101 /* the iWMMXt context must be 64 bit aligned */
102 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
103 if (__copy_from_user(kframe, frame, sizeof(*frame)))
104 return -1;
105 if (kframe->magic != IWMMXT_MAGIC ||
106 kframe->size != IWMMXT_STORAGE_SIZE)
107 return -1;
108 iwmmxt_task_restore(current_thread_info(), &kframe->storage);
109 return 0;
110 }
111
112 #endif
113
114 #ifdef CONFIG_VFP
115
preserve_vfp_context(struct vfp_sigframe __user * frame)116 static int preserve_vfp_context(struct vfp_sigframe __user *frame)
117 {
118 const unsigned long magic = VFP_MAGIC;
119 const unsigned long size = VFP_STORAGE_SIZE;
120 int err = 0;
121
122 __put_user_error(magic, &frame->magic, err);
123 __put_user_error(size, &frame->size, err);
124
125 if (err)
126 return -EFAULT;
127
128 return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc);
129 }
130
restore_vfp_context(struct vfp_sigframe __user * frame)131 static int restore_vfp_context(struct vfp_sigframe __user *frame)
132 {
133 unsigned long magic;
134 unsigned long size;
135 int err = 0;
136
137 __get_user_error(magic, &frame->magic, err);
138 __get_user_error(size, &frame->size, err);
139
140 if (err)
141 return -EFAULT;
142 if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
143 return -EINVAL;
144
145 return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc);
146 }
147
148 #endif
149
150 /*
151 * Do a signal return; undo the signal stack. These are aligned to 64-bit.
152 */
153 struct sigframe {
154 struct ucontext uc;
155 unsigned long retcode[2];
156 };
157
158 struct rt_sigframe {
159 struct siginfo info;
160 struct sigframe sig;
161 };
162
restore_sigframe(struct pt_regs * regs,struct sigframe __user * sf)163 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
164 {
165 struct aux_sigframe __user *aux;
166 sigset_t set;
167 int err;
168
169 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
170 if (err == 0)
171 set_current_blocked(&set);
172
173 __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
174 __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
175 __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
176 __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
177 __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
178 __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
179 __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
180 __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
181 __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
182 __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
183 __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
184 __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
185 __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
186 __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
187 __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
188 __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
189 __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
190
191 err |= !valid_user_regs(regs);
192
193 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
194 #ifdef CONFIG_CRUNCH
195 if (err == 0)
196 err |= restore_crunch_context(&aux->crunch);
197 #endif
198 #ifdef CONFIG_IWMMXT
199 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
200 err |= restore_iwmmxt_context(&aux->iwmmxt);
201 #endif
202 #ifdef CONFIG_VFP
203 if (err == 0)
204 err |= restore_vfp_context(&aux->vfp);
205 #endif
206
207 return err;
208 }
209
sys_sigreturn(struct pt_regs * regs)210 asmlinkage int sys_sigreturn(struct pt_regs *regs)
211 {
212 struct sigframe __user *frame;
213
214 /* Always make any pending restarted system calls return -EINTR */
215 current_thread_info()->restart_block.fn = do_no_restart_syscall;
216
217 /*
218 * Since we stacked the signal on a 64-bit boundary,
219 * then 'sp' should be word aligned here. If it's
220 * not, then the user is trying to mess with us.
221 */
222 if (regs->ARM_sp & 7)
223 goto badframe;
224
225 frame = (struct sigframe __user *)regs->ARM_sp;
226
227 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
228 goto badframe;
229
230 if (restore_sigframe(regs, frame))
231 goto badframe;
232
233 return regs->ARM_r0;
234
235 badframe:
236 force_sig(SIGSEGV, current);
237 return 0;
238 }
239
sys_rt_sigreturn(struct pt_regs * regs)240 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
241 {
242 struct rt_sigframe __user *frame;
243
244 /* Always make any pending restarted system calls return -EINTR */
245 current_thread_info()->restart_block.fn = do_no_restart_syscall;
246
247 /*
248 * Since we stacked the signal on a 64-bit boundary,
249 * then 'sp' should be word aligned here. If it's
250 * not, then the user is trying to mess with us.
251 */
252 if (regs->ARM_sp & 7)
253 goto badframe;
254
255 frame = (struct rt_sigframe __user *)regs->ARM_sp;
256
257 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
258 goto badframe;
259
260 if (restore_sigframe(regs, &frame->sig))
261 goto badframe;
262
263 if (restore_altstack(&frame->sig.uc.uc_stack))
264 goto badframe;
265
266 return regs->ARM_r0;
267
268 badframe:
269 force_sig(SIGSEGV, current);
270 return 0;
271 }
272
273 static int
setup_sigframe(struct sigframe __user * sf,struct pt_regs * regs,sigset_t * set)274 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
275 {
276 struct aux_sigframe __user *aux;
277 int err = 0;
278
279 __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
280 __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
281 __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
282 __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
283 __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
284 __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
285 __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
286 __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
287 __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
288 __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
289 __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
290 __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
291 __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
292 __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
293 __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
294 __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
295 __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
296
297 __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err);
298 __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err);
299 __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err);
300 __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
301
302 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
303
304 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
305 #ifdef CONFIG_CRUNCH
306 if (err == 0)
307 err |= preserve_crunch_context(&aux->crunch);
308 #endif
309 #ifdef CONFIG_IWMMXT
310 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
311 err |= preserve_iwmmxt_context(&aux->iwmmxt);
312 #endif
313 #ifdef CONFIG_VFP
314 if (err == 0)
315 err |= preserve_vfp_context(&aux->vfp);
316 #endif
317 __put_user_error(0, &aux->end_magic, err);
318
319 return err;
320 }
321
322 static inline void __user *
get_sigframe(struct ksignal * ksig,struct pt_regs * regs,int framesize)323 get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
324 {
325 unsigned long sp = sigsp(regs->ARM_sp, ksig);
326 void __user *frame;
327
328 /*
329 * ATPCS B01 mandates 8-byte alignment
330 */
331 frame = (void __user *)((sp - framesize) & ~7);
332
333 /*
334 * Check that we can actually write to the signal frame.
335 */
336 if (!access_ok(VERIFY_WRITE, frame, framesize))
337 frame = NULL;
338
339 return frame;
340 }
341
342 /*
343 * translate the signal
344 */
map_sig(int sig)345 static inline int map_sig(int sig)
346 {
347 struct thread_info *thread = current_thread_info();
348 if (sig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
349 sig = thread->exec_domain->signal_invmap[sig];
350 return sig;
351 }
352
353 static int
setup_return(struct pt_regs * regs,struct ksignal * ksig,unsigned long __user * rc,void __user * frame)354 setup_return(struct pt_regs *regs, struct ksignal *ksig,
355 unsigned long __user *rc, void __user *frame)
356 {
357 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
358 unsigned long retcode;
359 int thumb = 0;
360 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
361
362 cpsr |= PSR_ENDSTATE;
363
364 /*
365 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
366 */
367 if (ksig->ka.sa.sa_flags & SA_THIRTYTWO)
368 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
369
370 #ifdef CONFIG_ARM_THUMB
371 if (elf_hwcap & HWCAP_THUMB) {
372 /*
373 * The LSB of the handler determines if we're going to
374 * be using THUMB or ARM mode for this signal handler.
375 */
376 thumb = handler & 1;
377
378 if (thumb) {
379 cpsr |= PSR_T_BIT;
380 #if __LINUX_ARM_ARCH__ >= 7
381 /* clear the If-Then Thumb-2 execution state */
382 cpsr &= ~PSR_IT_MASK;
383 #endif
384 } else
385 cpsr &= ~PSR_T_BIT;
386 }
387 #endif
388
389 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
390 retcode = (unsigned long)ksig->ka.sa.sa_restorer;
391 } else {
392 unsigned int idx = thumb << 1;
393
394 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
395 idx += 3;
396
397 if (__put_user(sigreturn_codes[idx], rc) ||
398 __put_user(sigreturn_codes[idx+1], rc+1))
399 return 1;
400
401 if (cpsr & MODE32_BIT) {
402 struct mm_struct *mm = current->mm;
403
404 /*
405 * 32-bit code can use the new high-page
406 * signal return code support.
407 */
408 retcode = mm->context.sigpage + signal_return_offset +
409 (idx << 2) + thumb;
410 } else {
411 /*
412 * Ensure that the instruction cache sees
413 * the return code written onto the stack.
414 */
415 flush_icache_range((unsigned long)rc,
416 (unsigned long)(rc + 2));
417
418 retcode = ((unsigned long)rc) + thumb;
419 }
420 }
421
422 regs->ARM_r0 = map_sig(ksig->sig);
423 regs->ARM_sp = (unsigned long)frame;
424 regs->ARM_lr = retcode;
425 regs->ARM_pc = handler;
426 regs->ARM_cpsr = cpsr;
427
428 return 0;
429 }
430
431 static int
setup_frame(struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)432 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
433 {
434 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
435 int err = 0;
436
437 if (!frame)
438 return 1;
439
440 /*
441 * Set uc.uc_flags to a value which sc.trap_no would never have.
442 */
443 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
444
445 err |= setup_sigframe(frame, regs, set);
446 if (err == 0)
447 err = setup_return(regs, ksig, frame->retcode, frame);
448
449 return err;
450 }
451
452 static int
setup_rt_frame(struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)453 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
454 {
455 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
456 int err = 0;
457
458 if (!frame)
459 return 1;
460
461 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
462
463 __put_user_error(0, &frame->sig.uc.uc_flags, err);
464 __put_user_error(NULL, &frame->sig.uc.uc_link, err);
465
466 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp);
467 err |= setup_sigframe(&frame->sig, regs, set);
468 if (err == 0)
469 err = setup_return(regs, ksig, frame->sig.retcode, frame);
470
471 if (err == 0) {
472 /*
473 * For realtime signals we must also set the second and third
474 * arguments for the signal handler.
475 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
476 */
477 regs->ARM_r1 = (unsigned long)&frame->info;
478 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
479 }
480
481 return err;
482 }
483
484 /*
485 * OK, we're invoking a handler
486 */
handle_signal(struct ksignal * ksig,struct pt_regs * regs)487 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
488 {
489 sigset_t *oldset = sigmask_to_save();
490 int ret;
491
492 /*
493 * Set up the stack frame
494 */
495 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
496 ret = setup_rt_frame(ksig, oldset, regs);
497 else
498 ret = setup_frame(ksig, oldset, regs);
499
500 /*
501 * Check that the resulting registers are actually sane.
502 */
503 ret |= !valid_user_regs(regs);
504
505 signal_setup_done(ret, ksig, 0);
506 }
507
508 /*
509 * Note that 'init' is a special process: it doesn't get signals it doesn't
510 * want to handle. Thus you cannot kill init even with a SIGKILL even by
511 * mistake.
512 *
513 * Note that we go through the signals twice: once to check the signals that
514 * the kernel can handle, and then we build all the user-level signal handling
515 * stack-frames in one go after that.
516 */
do_signal(struct pt_regs * regs,int syscall)517 static int do_signal(struct pt_regs *regs, int syscall)
518 {
519 unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
520 struct ksignal ksig;
521 int restart = 0;
522
523 /*
524 * If we were from a system call, check for system call restarting...
525 */
526 if (syscall) {
527 continue_addr = regs->ARM_pc;
528 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
529 retval = regs->ARM_r0;
530
531 /*
532 * Prepare for system call restart. We do this here so that a
533 * debugger will see the already changed PSW.
534 */
535 switch (retval) {
536 case -ERESTART_RESTARTBLOCK:
537 restart -= 2;
538 case -ERESTARTNOHAND:
539 case -ERESTARTSYS:
540 case -ERESTARTNOINTR:
541 restart++;
542 regs->ARM_r0 = regs->ARM_ORIG_r0;
543 regs->ARM_pc = restart_addr;
544 break;
545 }
546 }
547
548 /*
549 * Get the signal to deliver. When running under ptrace, at this
550 * point the debugger may change all our registers ...
551 */
552 /*
553 * Depending on the signal settings we may need to revert the
554 * decision to restart the system call. But skip this if a
555 * debugger has chosen to restart at a different PC.
556 */
557 if (get_signal(&ksig)) {
558 /* handler */
559 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
560 if (retval == -ERESTARTNOHAND ||
561 retval == -ERESTART_RESTARTBLOCK
562 || (retval == -ERESTARTSYS
563 && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
564 regs->ARM_r0 = -EINTR;
565 regs->ARM_pc = continue_addr;
566 }
567 }
568 handle_signal(&ksig, regs);
569 } else {
570 /* no handler */
571 restore_saved_sigmask();
572 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
573 regs->ARM_pc = continue_addr;
574 return restart;
575 }
576 }
577 return 0;
578 }
579
580 asmlinkage int
do_work_pending(struct pt_regs * regs,unsigned int thread_flags,int syscall)581 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
582 {
583 do {
584 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
585 schedule();
586 } else {
587 if (unlikely(!user_mode(regs)))
588 return 0;
589 local_irq_enable();
590 if (thread_flags & _TIF_SIGPENDING) {
591 int restart = do_signal(regs, syscall);
592 if (unlikely(restart)) {
593 /*
594 * Restart without handlers.
595 * Deal with it without leaving
596 * the kernel space.
597 */
598 return restart;
599 }
600 syscall = 0;
601 } else {
602 clear_thread_flag(TIF_NOTIFY_RESUME);
603 tracehook_notify_resume(regs);
604 }
605 }
606 local_irq_disable();
607 thread_flags = current_thread_info()->flags;
608 } while (thread_flags & _TIF_WORK_MASK);
609 return 0;
610 }
611
get_signal_page(void)612 struct page *get_signal_page(void)
613 {
614 unsigned long ptr;
615 unsigned offset;
616 struct page *page;
617 void *addr;
618
619 page = alloc_pages(GFP_KERNEL, 0);
620
621 if (!page)
622 return NULL;
623
624 addr = page_address(page);
625
626 /* Give the signal return code some randomness */
627 offset = 0x200 + (get_random_int() & 0x7fc);
628 signal_return_offset = offset;
629
630 /*
631 * Copy signal return handlers into the vector page, and
632 * set sigreturn to be a pointer to these.
633 */
634 memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
635
636 ptr = (unsigned long)addr + offset;
637 flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
638
639 return page;
640 }
641