2 * linux/arch/arm/kernel/signal.c
4 * Copyright (C) 1995-2009 Russell King
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.
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>
19 #include <asm/cacheflush.h>
20 #include <asm/traps.h>
21 #include <asm/ucontext.h>
22 #include <asm/unistd.h>
25 extern const unsigned long sigreturn_codes[7];
27 static unsigned long signal_return_offset;
30 static int preserve_crunch_context(struct crunch_sigframe __user *frame)
32 char kbuf[sizeof(*frame) + 8];
33 struct crunch_sigframe *kframe;
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));
43 static int restore_crunch_context(char __user **auxp)
45 struct crunch_sigframe __user *frame =
46 (struct crunch_sigframe __user *)*auxp;
47 char kbuf[sizeof(*frame) + 8];
48 struct crunch_sigframe *kframe;
50 /* the crunch context must be 64 bit aligned */
51 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
52 if (__copy_from_user(kframe, frame, sizeof(*frame)))
54 if (kframe->magic != CRUNCH_MAGIC ||
55 kframe->size != CRUNCH_STORAGE_SIZE)
57 *auxp += CRUNCH_STORAGE_SIZE;
58 crunch_task_restore(current_thread_info(), &kframe->storage);
65 static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame)
67 char kbuf[sizeof(*frame) + 8];
68 struct iwmmxt_sigframe *kframe;
71 /* the iWMMXt context must be 64 bit aligned */
72 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
74 if (test_thread_flag(TIF_USING_IWMMXT)) {
75 kframe->magic = IWMMXT_MAGIC;
76 kframe->size = IWMMXT_STORAGE_SIZE;
77 iwmmxt_task_copy(current_thread_info(), &kframe->storage);
79 err = __copy_to_user(frame, kframe, sizeof(*frame));
82 * For bug-compatibility with older kernels, some space
83 * has to be reserved for iWMMXt even if it's not used.
84 * Set the magic and size appropriately so that properly
85 * written userspace can skip it reliably:
87 __put_user_error(DUMMY_MAGIC, &frame->magic, err);
88 __put_user_error(IWMMXT_STORAGE_SIZE, &frame->size, err);
94 static int restore_iwmmxt_context(char __user **auxp)
96 struct iwmmxt_sigframe __user *frame =
97 (struct iwmmxt_sigframe __user *)*auxp;
98 char kbuf[sizeof(*frame) + 8];
99 struct iwmmxt_sigframe *kframe;
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)))
107 * For non-iWMMXt threads: a single iwmmxt_sigframe-sized dummy
108 * block is discarded for compatibility with setup_sigframe() if
109 * present, but we don't mandate its presence. If some other
110 * magic is here, it's not for us:
112 if (!test_thread_flag(TIF_USING_IWMMXT) &&
113 kframe->magic != DUMMY_MAGIC)
116 if (kframe->size != IWMMXT_STORAGE_SIZE)
119 if (test_thread_flag(TIF_USING_IWMMXT)) {
120 if (kframe->magic != IWMMXT_MAGIC)
123 iwmmxt_task_restore(current_thread_info(), &kframe->storage);
126 *auxp += IWMMXT_STORAGE_SIZE;
134 static int preserve_vfp_context(struct vfp_sigframe __user *frame)
136 const unsigned long magic = VFP_MAGIC;
137 const unsigned long size = VFP_STORAGE_SIZE;
140 __put_user_error(magic, &frame->magic, err);
141 __put_user_error(size, &frame->size, err);
146 return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc);
149 static int restore_vfp_context(char __user **auxp)
151 struct vfp_sigframe __user *frame =
152 (struct vfp_sigframe __user *)*auxp;
157 __get_user_error(magic, &frame->magic, err);
158 __get_user_error(size, &frame->size, err);
162 if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
166 return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc);
172 * Do a signal return; undo the signal stack. These are aligned to 64-bit.
176 unsigned long retcode[2];
184 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
190 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
192 set_current_blocked(&set);
194 __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
195 __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
196 __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
197 __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
198 __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
199 __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
200 __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
201 __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
202 __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
203 __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
204 __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
205 __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
206 __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
207 __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
208 __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
209 __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
210 __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
212 err |= !valid_user_regs(regs);
214 aux = (char __user *) sf->uc.uc_regspace;
217 err |= restore_crunch_context(&aux);
221 err |= restore_iwmmxt_context(&aux);
225 err |= restore_vfp_context(&aux);
231 asmlinkage int sys_sigreturn(struct pt_regs *regs)
233 struct sigframe __user *frame;
235 /* Always make any pending restarted system calls return -EINTR */
236 current->restart_block.fn = do_no_restart_syscall;
239 * Since we stacked the signal on a 64-bit boundary,
240 * then 'sp' should be word aligned here. If it's
241 * not, then the user is trying to mess with us.
243 if (regs->ARM_sp & 7)
246 frame = (struct sigframe __user *)regs->ARM_sp;
248 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
251 if (restore_sigframe(regs, frame))
257 force_sig(SIGSEGV, current);
261 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
263 struct rt_sigframe __user *frame;
265 /* Always make any pending restarted system calls return -EINTR */
266 current->restart_block.fn = do_no_restart_syscall;
269 * Since we stacked the signal on a 64-bit boundary,
270 * then 'sp' should be word aligned here. If it's
271 * not, then the user is trying to mess with us.
273 if (regs->ARM_sp & 7)
276 frame = (struct rt_sigframe __user *)regs->ARM_sp;
278 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
281 if (restore_sigframe(regs, &frame->sig))
284 if (restore_altstack(&frame->sig.uc.uc_stack))
290 force_sig(SIGSEGV, current);
295 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
297 struct aux_sigframe __user *aux;
300 __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
301 __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
302 __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
303 __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
304 __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
305 __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
306 __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
307 __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
308 __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
309 __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
310 __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
311 __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
312 __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
313 __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
314 __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
315 __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
316 __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
318 __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err);
319 __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err);
320 __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err);
321 __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
323 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
325 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
328 err |= preserve_crunch_context(&aux->crunch);
332 err |= preserve_iwmmxt_context(&aux->iwmmxt);
336 err |= preserve_vfp_context(&aux->vfp);
338 __put_user_error(0, &aux->end_magic, err);
343 static inline void __user *
344 get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
346 unsigned long sp = sigsp(regs->ARM_sp, ksig);
350 * ATPCS B01 mandates 8-byte alignment
352 frame = (void __user *)((sp - framesize) & ~7);
355 * Check that we can actually write to the signal frame.
357 if (!access_ok(VERIFY_WRITE, frame, framesize))
364 setup_return(struct pt_regs *regs, struct ksignal *ksig,
365 unsigned long __user *rc, void __user *frame)
367 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
368 unsigned long retcode;
370 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
372 cpsr |= PSR_ENDSTATE;
375 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
377 if (ksig->ka.sa.sa_flags & SA_THIRTYTWO)
378 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
380 #ifdef CONFIG_ARM_THUMB
381 if (elf_hwcap & HWCAP_THUMB) {
383 * The LSB of the handler determines if we're going to
384 * be using THUMB or ARM mode for this signal handler.
389 * Clear the If-Then Thumb-2 execution state. ARM spec
390 * requires this to be all 000s in ARM mode. Snapdragon
391 * S4/Krait misbehaves on a Thumb=>ARM signal transition
394 * We must do this whenever we are running on a Thumb-2
395 * capable CPU, which includes ARMv6T2. However, we elect
396 * to always do this to simplify the code; this field is
397 * marked UNK/SBZP for older architectures.
399 cpsr &= ~PSR_IT_MASK;
408 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
409 retcode = (unsigned long)ksig->ka.sa.sa_restorer;
411 unsigned int idx = thumb << 1;
413 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
417 * Put the sigreturn code on the stack no matter which return
418 * mechanism we use in order to remain ABI compliant
420 if (__put_user(sigreturn_codes[idx], rc) ||
421 __put_user(sigreturn_codes[idx+1], rc+1))
425 if (cpsr & MODE32_BIT) {
426 struct mm_struct *mm = current->mm;
429 * 32-bit code can use the signal return page
430 * except when the MPU has protected the vectors
433 retcode = mm->context.sigpage + signal_return_offset +
439 * Ensure that the instruction cache sees
440 * the return code written onto the stack.
442 flush_icache_range((unsigned long)rc,
443 (unsigned long)(rc + 2));
445 retcode = ((unsigned long)rc) + thumb;
449 regs->ARM_r0 = ksig->sig;
450 regs->ARM_sp = (unsigned long)frame;
451 regs->ARM_lr = retcode;
452 regs->ARM_pc = handler;
453 regs->ARM_cpsr = cpsr;
459 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
461 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
468 * Set uc.uc_flags to a value which sc.trap_no would never have.
470 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
472 err |= setup_sigframe(frame, regs, set);
474 err = setup_return(regs, ksig, frame->retcode, frame);
480 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
482 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
488 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
490 __put_user_error(0, &frame->sig.uc.uc_flags, err);
491 __put_user_error(NULL, &frame->sig.uc.uc_link, err);
493 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp);
494 err |= setup_sigframe(&frame->sig, regs, set);
496 err = setup_return(regs, ksig, frame->sig.retcode, frame);
500 * For realtime signals we must also set the second and third
501 * arguments for the signal handler.
502 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
504 regs->ARM_r1 = (unsigned long)&frame->info;
505 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
512 * OK, we're invoking a handler
514 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
516 sigset_t *oldset = sigmask_to_save();
520 * Set up the stack frame
522 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
523 ret = setup_rt_frame(ksig, oldset, regs);
525 ret = setup_frame(ksig, oldset, regs);
528 * Check that the resulting registers are actually sane.
530 ret |= !valid_user_regs(regs);
532 signal_setup_done(ret, ksig, 0);
536 * Note that 'init' is a special process: it doesn't get signals it doesn't
537 * want to handle. Thus you cannot kill init even with a SIGKILL even by
540 * Note that we go through the signals twice: once to check the signals that
541 * the kernel can handle, and then we build all the user-level signal handling
542 * stack-frames in one go after that.
544 static int do_signal(struct pt_regs *regs, int syscall)
546 unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
551 * If we were from a system call, check for system call restarting...
554 continue_addr = regs->ARM_pc;
555 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
556 retval = regs->ARM_r0;
559 * Prepare for system call restart. We do this here so that a
560 * debugger will see the already changed PSW.
563 case -ERESTART_RESTARTBLOCK:
565 case -ERESTARTNOHAND:
567 case -ERESTARTNOINTR:
569 regs->ARM_r0 = regs->ARM_ORIG_r0;
570 regs->ARM_pc = restart_addr;
576 * Get the signal to deliver. When running under ptrace, at this
577 * point the debugger may change all our registers ...
580 * Depending on the signal settings we may need to revert the
581 * decision to restart the system call. But skip this if a
582 * debugger has chosen to restart at a different PC.
584 if (get_signal(&ksig)) {
586 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
587 if (retval == -ERESTARTNOHAND ||
588 retval == -ERESTART_RESTARTBLOCK
589 || (retval == -ERESTARTSYS
590 && !(ksig.ka.sa.sa_flags & SA_RESTART))) {
591 regs->ARM_r0 = -EINTR;
592 regs->ARM_pc = continue_addr;
595 handle_signal(&ksig, regs);
598 restore_saved_sigmask();
599 if (unlikely(restart) && regs->ARM_pc == restart_addr) {
600 regs->ARM_pc = continue_addr;
608 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
611 * The assembly code enters us with IRQs off, but it hasn't
612 * informed the tracing code of that for efficiency reasons.
613 * Update the trace code with the current status.
615 trace_hardirqs_off();
617 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
620 if (unlikely(!user_mode(regs)))
623 if (thread_flags & _TIF_SIGPENDING) {
624 int restart = do_signal(regs, syscall);
625 if (unlikely(restart)) {
627 * Restart without handlers.
628 * Deal with it without leaving
634 } else if (thread_flags & _TIF_UPROBE) {
635 uprobe_notify_resume(regs);
637 clear_thread_flag(TIF_NOTIFY_RESUME);
638 tracehook_notify_resume(regs);
642 thread_flags = current_thread_info()->flags;
643 } while (thread_flags & _TIF_WORK_MASK);
647 struct page *get_signal_page(void)
654 page = alloc_pages(GFP_KERNEL, 0);
659 addr = page_address(page);
661 /* Give the signal return code some randomness */
662 offset = 0x200 + (get_random_int() & 0x7fc);
663 signal_return_offset = offset;
666 * Copy signal return handlers into the vector page, and
667 * set sigreturn to be a pointer to these.
669 memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
671 ptr = (unsigned long)addr + offset;
672 flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));