2 * Based on arch/arm/kernel/signal.c
4 * Copyright (C) 1995-2009 Russell King
5 * Copyright (C) 2012 ARM Ltd.
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
20 #include <linux/compat.h>
21 #include <linux/errno.h>
22 #include <linux/kernel.h>
23 #include <linux/signal.h>
24 #include <linux/personality.h>
25 #include <linux/freezer.h>
26 #include <linux/stddef.h>
27 #include <linux/uaccess.h>
28 #include <linux/sizes.h>
29 #include <linux/string.h>
30 #include <linux/tracehook.h>
31 #include <linux/ratelimit.h>
33 #include <asm/debug-monitors.h>
35 #include <asm/cacheflush.h>
36 #include <asm/ucontext.h>
37 #include <asm/unistd.h>
38 #include <asm/fpsimd.h>
39 #include <asm/signal32.h>
43 * Do a signal return; undo the signal stack. These are aligned to 128-bit.
55 struct rt_sigframe_user_layout {
56 struct rt_sigframe __user *sigframe;
57 struct frame_record __user *next_frame;
59 unsigned long size; /* size of allocated sigframe data */
60 unsigned long limit; /* largest allowed size */
62 unsigned long fpsimd_offset;
63 unsigned long esr_offset;
64 unsigned long extra_offset;
65 unsigned long end_offset;
68 #define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
69 #define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
70 #define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
72 static void init_user_layout(struct rt_sigframe_user_layout *user)
74 const size_t reserved_size =
75 sizeof(user->sigframe->uc.uc_mcontext.__reserved);
77 memset(user, 0, sizeof(*user));
78 user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
80 user->limit = user->size + reserved_size;
82 user->limit -= TERMINATOR_SIZE;
83 user->limit -= EXTRA_CONTEXT_SIZE;
84 /* Reserve space for extension and terminator ^ */
87 static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
89 return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
93 * Sanity limit on the approximate maximum size of signal frame we'll
94 * try to generate. Stack alignment padding and the frame record are
95 * not taken into account. This limit is not a guarantee and is
98 #define SIGFRAME_MAXSZ SZ_64K
100 static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
101 unsigned long *offset, size_t size, bool extend)
103 size_t padded_size = round_up(size, 16);
105 if (padded_size > user->limit - user->size &&
106 !user->extra_offset &&
110 user->limit += EXTRA_CONTEXT_SIZE;
111 ret = __sigframe_alloc(user, &user->extra_offset,
112 sizeof(struct extra_context), false);
114 user->limit -= EXTRA_CONTEXT_SIZE;
118 /* Reserve space for the __reserved[] terminator */
119 user->size += TERMINATOR_SIZE;
122 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
125 user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
128 /* Still not enough space? Bad luck! */
129 if (padded_size > user->limit - user->size)
132 *offset = user->size;
133 user->size += padded_size;
139 * Allocate space for an optional record of <size> bytes in the user
140 * signal frame. The offset from the signal frame base address to the
141 * allocated block is assigned to *offset.
143 static int sigframe_alloc(struct rt_sigframe_user_layout *user,
144 unsigned long *offset, size_t size)
146 return __sigframe_alloc(user, offset, size, true);
149 /* Allocate the null terminator record and prevent further allocations */
150 static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
154 /* Un-reserve the space reserved for the terminator: */
155 user->limit += TERMINATOR_SIZE;
157 ret = sigframe_alloc(user, &user->end_offset,
158 sizeof(struct _aarch64_ctx));
162 /* Prevent further allocation: */
163 user->limit = user->size;
167 static void __user *apply_user_offset(
168 struct rt_sigframe_user_layout const *user, unsigned long offset)
170 char __user *base = (char __user *)user->sigframe;
172 return base + offset;
175 static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
177 struct fpsimd_state *fpsimd = ¤t->thread.fpsimd_state;
180 /* dump the hardware registers to the fpsimd_state structure */
181 fpsimd_preserve_current_state();
183 /* copy the FP and status/control registers */
184 err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
185 __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
186 __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
188 /* copy the magic/size information */
189 __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
190 __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
192 return err ? -EFAULT : 0;
195 static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
197 struct fpsimd_state fpsimd;
201 /* check the magic/size information */
202 __get_user_error(magic, &ctx->head.magic, err);
203 __get_user_error(size, &ctx->head.size, err);
206 if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
209 /* copy the FP and status/control registers */
210 err = __copy_from_user(fpsimd.vregs, ctx->vregs,
211 sizeof(fpsimd.vregs));
212 __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
213 __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
215 /* load the hardware registers from the fpsimd_state structure */
217 fpsimd_update_current_state(&fpsimd);
219 return err ? -EFAULT : 0;
223 struct fpsimd_context __user *fpsimd;
226 static int parse_user_sigframe(struct user_ctxs *user,
227 struct rt_sigframe __user *sf)
229 struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
230 struct _aarch64_ctx __user *head;
231 char __user *base = (char __user *)&sc->__reserved;
233 size_t limit = sizeof(sc->__reserved);
234 bool have_extra_context = false;
235 char const __user *const sfp = (char const __user *)sf;
239 if (!IS_ALIGNED((unsigned long)base, 16))
245 char const __user *userp;
246 struct extra_context const __user *extra;
249 struct _aarch64_ctx const __user *end;
250 u32 end_magic, end_size;
252 if (limit - offset < sizeof(*head))
255 if (!IS_ALIGNED(offset, 16))
258 head = (struct _aarch64_ctx __user *)(base + offset);
259 __get_user_error(magic, &head->magic, err);
260 __get_user_error(size, &head->size, err);
264 if (limit - offset < size)
278 if (size < sizeof(*user->fpsimd))
281 user->fpsimd = (struct fpsimd_context __user *)head;
289 if (have_extra_context)
292 if (size < sizeof(*extra))
295 userp = (char const __user *)head;
297 extra = (struct extra_context const __user *)userp;
300 __get_user_error(extra_datap, &extra->datap, err);
301 __get_user_error(extra_size, &extra->size, err);
305 /* Check for the dummy terminator in __reserved[]: */
307 if (limit - offset - size < TERMINATOR_SIZE)
310 end = (struct _aarch64_ctx const __user *)userp;
311 userp += TERMINATOR_SIZE;
313 __get_user_error(end_magic, &end->magic, err);
314 __get_user_error(end_size, &end->size, err);
318 if (end_magic || end_size)
321 /* Prevent looping/repeated parsing of extra_context */
322 have_extra_context = true;
324 base = (__force void __user *)extra_datap;
325 if (!IS_ALIGNED((unsigned long)base, 16))
328 if (!IS_ALIGNED(extra_size, 16))
334 /* Reject "unreasonably large" frames: */
335 if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
339 * Ignore trailing terminator in __reserved[]
340 * and start parsing extra data:
350 if (size < sizeof(*head))
353 if (limit - offset < size)
369 static int restore_sigframe(struct pt_regs *regs,
370 struct rt_sigframe __user *sf)
374 struct user_ctxs user;
376 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
378 set_current_blocked(&set);
380 for (i = 0; i < 31; i++)
381 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
383 __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
384 __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
385 __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
388 * Avoid sys_rt_sigreturn() restarting.
390 regs->syscallno = ~0UL;
392 err |= !valid_user_regs(®s->user_regs, current);
394 err = parse_user_sigframe(&user, sf);
397 err = restore_fpsimd_context(user.fpsimd);
402 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
404 struct rt_sigframe __user *frame;
406 /* Always make any pending restarted system calls return -EINTR */
407 current->restart_block.fn = do_no_restart_syscall;
410 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
411 * be word aligned here.
416 frame = (struct rt_sigframe __user *)regs->sp;
418 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
421 if (restore_sigframe(regs, frame))
424 if (restore_altstack(&frame->uc.uc_stack))
427 return regs->regs[0];
430 if (show_unhandled_signals)
431 pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
432 current->comm, task_pid_nr(current), __func__,
434 force_sig(SIGSEGV, current);
438 /* Determine the layout of optional records in the signal frame */
439 static int setup_sigframe_layout(struct rt_sigframe_user_layout *user)
443 err = sigframe_alloc(user, &user->fpsimd_offset,
444 sizeof(struct fpsimd_context));
448 /* fault information, if valid */
449 if (current->thread.fault_code) {
450 err = sigframe_alloc(user, &user->esr_offset,
451 sizeof(struct esr_context));
456 return sigframe_alloc_end(user);
460 static int setup_sigframe(struct rt_sigframe_user_layout *user,
461 struct pt_regs *regs, sigset_t *set)
464 struct rt_sigframe __user *sf = user->sigframe;
466 /* set up the stack frame for unwinding */
467 __put_user_error(regs->regs[29], &user->next_frame->fp, err);
468 __put_user_error(regs->regs[30], &user->next_frame->lr, err);
470 for (i = 0; i < 31; i++)
471 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
473 __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
474 __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
475 __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
477 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
479 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
482 struct fpsimd_context __user *fpsimd_ctx =
483 apply_user_offset(user, user->fpsimd_offset);
484 err |= preserve_fpsimd_context(fpsimd_ctx);
487 /* fault information, if valid */
488 if (err == 0 && user->esr_offset) {
489 struct esr_context __user *esr_ctx =
490 apply_user_offset(user, user->esr_offset);
492 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
493 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
494 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
497 if (err == 0 && user->extra_offset) {
498 char __user *sfp = (char __user *)user->sigframe;
500 apply_user_offset(user, user->extra_offset);
502 struct extra_context __user *extra;
503 struct _aarch64_ctx __user *end;
507 extra = (struct extra_context __user *)userp;
508 userp += EXTRA_CONTEXT_SIZE;
510 end = (struct _aarch64_ctx __user *)userp;
511 userp += TERMINATOR_SIZE;
514 * extra_datap is just written to the signal frame.
515 * The value gets cast back to a void __user *
518 extra_datap = (__force u64)userp;
519 extra_size = sfp + round_up(user->size, 16) - userp;
521 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
522 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
523 __put_user_error(extra_datap, &extra->datap, err);
524 __put_user_error(extra_size, &extra->size, err);
526 /* Add the terminator */
527 __put_user_error(0, &end->magic, err);
528 __put_user_error(0, &end->size, err);
531 /* set the "end" magic */
533 struct _aarch64_ctx __user *end =
534 apply_user_offset(user, user->end_offset);
536 __put_user_error(0, &end->magic, err);
537 __put_user_error(0, &end->size, err);
543 static int get_sigframe(struct rt_sigframe_user_layout *user,
544 struct ksignal *ksig, struct pt_regs *regs)
546 unsigned long sp, sp_top;
549 init_user_layout(user);
550 err = setup_sigframe_layout(user);
554 sp = sp_top = sigsp(regs->sp, ksig);
556 sp = round_down(sp - sizeof(struct frame_record), 16);
557 user->next_frame = (struct frame_record __user *)sp;
559 sp = round_down(sp, 16) - sigframe_size(user);
560 user->sigframe = (struct rt_sigframe __user *)sp;
563 * Check that we can actually write to the signal frame.
565 if (!access_ok(VERIFY_WRITE, user->sigframe, sp_top - sp))
571 static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
572 struct rt_sigframe_user_layout *user, int usig)
574 __sigrestore_t sigtramp;
576 regs->regs[0] = usig;
577 regs->sp = (unsigned long)user->sigframe;
578 regs->regs[29] = (unsigned long)&user->next_frame->fp;
579 regs->pc = (unsigned long)ka->sa.sa_handler;
581 if (ka->sa.sa_flags & SA_RESTORER)
582 sigtramp = ka->sa.sa_restorer;
584 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
586 regs->regs[30] = (unsigned long)sigtramp;
589 static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
590 struct pt_regs *regs)
592 struct rt_sigframe_user_layout user;
593 struct rt_sigframe __user *frame;
596 if (get_sigframe(&user, ksig, regs))
599 frame = user.sigframe;
601 __put_user_error(0, &frame->uc.uc_flags, err);
602 __put_user_error(NULL, &frame->uc.uc_link, err);
604 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
605 err |= setup_sigframe(&user, regs, set);
607 setup_return(regs, &ksig->ka, &user, usig);
608 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
609 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
610 regs->regs[1] = (unsigned long)&frame->info;
611 regs->regs[2] = (unsigned long)&frame->uc;
618 static void setup_restart_syscall(struct pt_regs *regs)
620 if (is_compat_task())
621 compat_setup_restart_syscall(regs);
623 regs->regs[8] = __NR_restart_syscall;
627 * OK, we're invoking a handler
629 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
631 struct task_struct *tsk = current;
632 sigset_t *oldset = sigmask_to_save();
633 int usig = ksig->sig;
637 * Set up the stack frame
639 if (is_compat_task()) {
640 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
641 ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
643 ret = compat_setup_frame(usig, ksig, oldset, regs);
645 ret = setup_rt_frame(usig, ksig, oldset, regs);
649 * Check that the resulting registers are actually sane.
651 ret |= !valid_user_regs(®s->user_regs, current);
654 * Fast forward the stepping logic so we step into the signal
658 user_fastforward_single_step(tsk);
660 signal_setup_done(ret, ksig, 0);
664 * Note that 'init' is a special process: it doesn't get signals it doesn't
665 * want to handle. Thus you cannot kill init even with a SIGKILL even by
668 * Note that we go through the signals twice: once to check the signals that
669 * the kernel can handle, and then we build all the user-level signal handling
670 * stack-frames in one go after that.
672 static void do_signal(struct pt_regs *regs)
674 unsigned long continue_addr = 0, restart_addr = 0;
676 int syscall = (int)regs->syscallno;
680 * If we were from a system call, check for system call restarting...
683 continue_addr = regs->pc;
684 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
685 retval = regs->regs[0];
688 * Avoid additional syscall restarting via ret_to_user.
690 regs->syscallno = ~0UL;
693 * Prepare for system call restart. We do this here so that a
694 * debugger will see the already changed PC.
697 case -ERESTARTNOHAND:
699 case -ERESTARTNOINTR:
700 case -ERESTART_RESTARTBLOCK:
701 regs->regs[0] = regs->orig_x0;
702 regs->pc = restart_addr;
708 * Get the signal to deliver. When running under ptrace, at this point
709 * the debugger may change all of our registers.
711 if (get_signal(&ksig)) {
713 * Depending on the signal settings, we may need to revert the
714 * decision to restart the system call, but skip this if a
715 * debugger has chosen to restart at a different PC.
717 if (regs->pc == restart_addr &&
718 (retval == -ERESTARTNOHAND ||
719 retval == -ERESTART_RESTARTBLOCK ||
720 (retval == -ERESTARTSYS &&
721 !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
722 regs->regs[0] = -EINTR;
723 regs->pc = continue_addr;
726 handle_signal(&ksig, regs);
731 * Handle restarting a different system call. As above, if a debugger
732 * has chosen to restart at a different PC, ignore the restart.
734 if (syscall >= 0 && regs->pc == restart_addr) {
735 if (retval == -ERESTART_RESTARTBLOCK)
736 setup_restart_syscall(regs);
737 user_rewind_single_step(current);
740 restore_saved_sigmask();
743 asmlinkage void do_notify_resume(struct pt_regs *regs,
744 unsigned int thread_flags)
747 * The assembly code enters us with IRQs off, but it hasn't
748 * informed the tracing code of that for efficiency reasons.
749 * Update the trace code with the current status.
751 trace_hardirqs_off();
753 if (thread_flags & _TIF_NEED_RESCHED) {
758 if (thread_flags & _TIF_UPROBE)
759 uprobe_notify_resume(regs);
761 if (thread_flags & _TIF_SIGPENDING)
764 if (thread_flags & _TIF_NOTIFY_RESUME) {
765 clear_thread_flag(TIF_NOTIFY_RESUME);
766 tracehook_notify_resume(regs);
769 if (thread_flags & _TIF_FOREIGN_FPSTATE)
770 fpsimd_restore_current_state();
774 thread_flags = READ_ONCE(current_thread_info()->flags);
775 } while (thread_flags & _TIF_WORK_MASK);