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>
32 #include <linux/syscalls.h>
34 #include <asm/daifflags.h>
35 #include <asm/debug-monitors.h>
37 #include <asm/cacheflush.h>
38 #include <asm/ucontext.h>
39 #include <asm/unistd.h>
40 #include <asm/fpsimd.h>
41 #include <asm/ptrace.h>
42 #include <asm/signal32.h>
46 * Do a signal return; undo the signal stack. These are aligned to 128-bit.
58 struct rt_sigframe_user_layout {
59 struct rt_sigframe __user *sigframe;
60 struct frame_record __user *next_frame;
62 unsigned long size; /* size of allocated sigframe data */
63 unsigned long limit; /* largest allowed size */
65 unsigned long fpsimd_offset;
66 unsigned long esr_offset;
67 unsigned long sve_offset;
68 unsigned long extra_offset;
69 unsigned long end_offset;
72 #define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
73 #define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
74 #define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
76 static void init_user_layout(struct rt_sigframe_user_layout *user)
78 const size_t reserved_size =
79 sizeof(user->sigframe->uc.uc_mcontext.__reserved);
81 memset(user, 0, sizeof(*user));
82 user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
84 user->limit = user->size + reserved_size;
86 user->limit -= TERMINATOR_SIZE;
87 user->limit -= EXTRA_CONTEXT_SIZE;
88 /* Reserve space for extension and terminator ^ */
91 static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
93 return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
97 * Sanity limit on the approximate maximum size of signal frame we'll
98 * try to generate. Stack alignment padding and the frame record are
99 * not taken into account. This limit is not a guarantee and is
102 #define SIGFRAME_MAXSZ SZ_64K
104 static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
105 unsigned long *offset, size_t size, bool extend)
107 size_t padded_size = round_up(size, 16);
109 if (padded_size > user->limit - user->size &&
110 !user->extra_offset &&
114 user->limit += EXTRA_CONTEXT_SIZE;
115 ret = __sigframe_alloc(user, &user->extra_offset,
116 sizeof(struct extra_context), false);
118 user->limit -= EXTRA_CONTEXT_SIZE;
122 /* Reserve space for the __reserved[] terminator */
123 user->size += TERMINATOR_SIZE;
126 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
129 user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
132 /* Still not enough space? Bad luck! */
133 if (padded_size > user->limit - user->size)
136 *offset = user->size;
137 user->size += padded_size;
143 * Allocate space for an optional record of <size> bytes in the user
144 * signal frame. The offset from the signal frame base address to the
145 * allocated block is assigned to *offset.
147 static int sigframe_alloc(struct rt_sigframe_user_layout *user,
148 unsigned long *offset, size_t size)
150 return __sigframe_alloc(user, offset, size, true);
153 /* Allocate the null terminator record and prevent further allocations */
154 static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
158 /* Un-reserve the space reserved for the terminator: */
159 user->limit += TERMINATOR_SIZE;
161 ret = sigframe_alloc(user, &user->end_offset,
162 sizeof(struct _aarch64_ctx));
166 /* Prevent further allocation: */
167 user->limit = user->size;
171 static void __user *apply_user_offset(
172 struct rt_sigframe_user_layout const *user, unsigned long offset)
174 char __user *base = (char __user *)user->sigframe;
176 return base + offset;
179 static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
181 struct fpsimd_state *fpsimd = ¤t->thread.fpsimd_state;
184 /* copy the FP and status/control registers */
185 err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
186 __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
187 __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
189 /* copy the magic/size information */
190 __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
191 __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
193 return err ? -EFAULT : 0;
196 static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
198 struct fpsimd_state fpsimd;
202 /* check the magic/size information */
203 __get_user_error(magic, &ctx->head.magic, err);
204 __get_user_error(size, &ctx->head.size, err);
207 if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
210 /* copy the FP and status/control registers */
211 err = __copy_from_user(fpsimd.vregs, ctx->vregs,
212 sizeof(fpsimd.vregs));
213 __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
214 __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
216 clear_thread_flag(TIF_SVE);
218 /* load the hardware registers from the fpsimd_state structure */
220 fpsimd_update_current_state(&fpsimd);
222 return err ? -EFAULT : 0;
227 struct fpsimd_context __user *fpsimd;
228 struct sve_context __user *sve;
231 #ifdef CONFIG_ARM64_SVE
233 static int preserve_sve_context(struct sve_context __user *ctx)
236 u16 reserved[ARRAY_SIZE(ctx->__reserved)];
237 unsigned int vl = current->thread.sve_vl;
240 if (test_thread_flag(TIF_SVE))
241 vq = sve_vq_from_vl(vl);
243 memset(reserved, 0, sizeof(reserved));
245 __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
246 __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
247 &ctx->head.size, err);
248 __put_user_error(vl, &ctx->vl, err);
249 BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
250 err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
254 * This assumes that the SVE state has already been saved to
255 * the task struct by calling preserve_fpsimd_context().
257 err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
258 current->thread.sve_state,
259 SVE_SIG_REGS_SIZE(vq));
262 return err ? -EFAULT : 0;
265 static int restore_sve_fpsimd_context(struct user_ctxs *user)
269 struct fpsimd_state fpsimd;
270 struct sve_context sve;
272 if (__copy_from_user(&sve, user->sve, sizeof(sve)))
275 if (sve.vl != current->thread.sve_vl)
278 if (sve.head.size <= sizeof(*user->sve)) {
279 clear_thread_flag(TIF_SVE);
283 vq = sve_vq_from_vl(sve.vl);
285 if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
289 * Careful: we are about __copy_from_user() directly into
290 * thread.sve_state with preemption enabled, so protection is
291 * needed to prevent a racing context switch from writing stale
292 * registers back over the new data.
295 fpsimd_flush_task_state(current);
297 /* From now, fpsimd_thread_switch() won't clear TIF_FOREIGN_FPSTATE */
299 set_thread_flag(TIF_FOREIGN_FPSTATE);
301 /* From now, fpsimd_thread_switch() won't touch thread.sve_state */
304 err = __copy_from_user(current->thread.sve_state,
305 (char __user const *)user->sve +
307 SVE_SIG_REGS_SIZE(vq));
311 set_thread_flag(TIF_SVE);
314 /* copy the FP and status/control registers */
315 /* restore_sigframe() already checked that user->fpsimd != NULL. */
316 err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
317 sizeof(fpsimd.vregs));
318 __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
319 __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
321 /* load the hardware registers from the fpsimd_state structure */
323 fpsimd_update_current_state(&fpsimd);
325 return err ? -EFAULT : 0;
328 #else /* ! CONFIG_ARM64_SVE */
330 /* Turn any non-optimised out attempts to use these into a link error: */
331 extern int preserve_sve_context(void __user *ctx);
332 extern int restore_sve_fpsimd_context(struct user_ctxs *user);
334 #endif /* ! CONFIG_ARM64_SVE */
337 static int parse_user_sigframe(struct user_ctxs *user,
338 struct rt_sigframe __user *sf)
340 struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
341 struct _aarch64_ctx __user *head;
342 char __user *base = (char __user *)&sc->__reserved;
344 size_t limit = sizeof(sc->__reserved);
345 bool have_extra_context = false;
346 char const __user *const sfp = (char const __user *)sf;
351 if (!IS_ALIGNED((unsigned long)base, 16))
357 char const __user *userp;
358 struct extra_context const __user *extra;
361 struct _aarch64_ctx const __user *end;
362 u32 end_magic, end_size;
364 if (limit - offset < sizeof(*head))
367 if (!IS_ALIGNED(offset, 16))
370 head = (struct _aarch64_ctx __user *)(base + offset);
371 __get_user_error(magic, &head->magic, err);
372 __get_user_error(size, &head->size, err);
376 if (limit - offset < size)
390 if (size < sizeof(*user->fpsimd))
393 user->fpsimd = (struct fpsimd_context __user *)head;
401 if (!system_supports_sve())
407 if (size < sizeof(*user->sve))
410 user->sve = (struct sve_context __user *)head;
414 if (have_extra_context)
417 if (size < sizeof(*extra))
420 userp = (char const __user *)head;
422 extra = (struct extra_context const __user *)userp;
425 __get_user_error(extra_datap, &extra->datap, err);
426 __get_user_error(extra_size, &extra->size, err);
430 /* Check for the dummy terminator in __reserved[]: */
432 if (limit - offset - size < TERMINATOR_SIZE)
435 end = (struct _aarch64_ctx const __user *)userp;
436 userp += TERMINATOR_SIZE;
438 __get_user_error(end_magic, &end->magic, err);
439 __get_user_error(end_size, &end->size, err);
443 if (end_magic || end_size)
446 /* Prevent looping/repeated parsing of extra_context */
447 have_extra_context = true;
449 base = (__force void __user *)extra_datap;
450 if (!IS_ALIGNED((unsigned long)base, 16))
453 if (!IS_ALIGNED(extra_size, 16))
459 /* Reject "unreasonably large" frames: */
460 if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
464 * Ignore trailing terminator in __reserved[]
465 * and start parsing extra data:
470 if (!access_ok(VERIFY_READ, base, limit))
479 if (size < sizeof(*head))
482 if (limit - offset < size)
495 static int restore_sigframe(struct pt_regs *regs,
496 struct rt_sigframe __user *sf)
500 struct user_ctxs user;
502 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
504 set_current_blocked(&set);
506 for (i = 0; i < 31; i++)
507 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
509 __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
510 __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
511 __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
514 * Avoid sys_rt_sigreturn() restarting.
516 forget_syscall(regs);
518 err |= !valid_user_regs(®s->user_regs, current);
520 err = parse_user_sigframe(&user, sf);
527 if (!system_supports_sve())
530 err = restore_sve_fpsimd_context(&user);
532 err = restore_fpsimd_context(user.fpsimd);
539 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
541 struct rt_sigframe __user *frame;
543 /* Always make any pending restarted system calls return -EINTR */
544 current->restart_block.fn = do_no_restart_syscall;
547 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
548 * be word aligned here.
553 frame = (struct rt_sigframe __user *)regs->sp;
555 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
558 if (restore_sigframe(regs, frame))
561 if (restore_altstack(&frame->uc.uc_stack))
564 return regs->regs[0];
567 if (show_unhandled_signals)
568 pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
569 current->comm, task_pid_nr(current), __func__,
571 force_sig(SIGSEGV, current);
575 /* Determine the layout of optional records in the signal frame */
576 static int setup_sigframe_layout(struct rt_sigframe_user_layout *user)
580 err = sigframe_alloc(user, &user->fpsimd_offset,
581 sizeof(struct fpsimd_context));
585 /* fault information, if valid */
586 if (current->thread.fault_code) {
587 err = sigframe_alloc(user, &user->esr_offset,
588 sizeof(struct esr_context));
593 if (system_supports_sve()) {
596 if (test_thread_flag(TIF_SVE))
597 vq = sve_vq_from_vl(current->thread.sve_vl);
599 err = sigframe_alloc(user, &user->sve_offset,
600 SVE_SIG_CONTEXT_SIZE(vq));
605 return sigframe_alloc_end(user);
609 static int setup_sigframe(struct rt_sigframe_user_layout *user,
610 struct pt_regs *regs, sigset_t *set)
613 struct rt_sigframe __user *sf = user->sigframe;
615 /* set up the stack frame for unwinding */
616 __put_user_error(regs->regs[29], &user->next_frame->fp, err);
617 __put_user_error(regs->regs[30], &user->next_frame->lr, err);
619 for (i = 0; i < 31; i++)
620 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
622 __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
623 __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
624 __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
626 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
628 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
631 struct fpsimd_context __user *fpsimd_ctx =
632 apply_user_offset(user, user->fpsimd_offset);
633 err |= preserve_fpsimd_context(fpsimd_ctx);
636 /* fault information, if valid */
637 if (err == 0 && user->esr_offset) {
638 struct esr_context __user *esr_ctx =
639 apply_user_offset(user, user->esr_offset);
641 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
642 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
643 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
646 /* Scalable Vector Extension state, if present */
647 if (system_supports_sve() && err == 0 && user->sve_offset) {
648 struct sve_context __user *sve_ctx =
649 apply_user_offset(user, user->sve_offset);
650 err |= preserve_sve_context(sve_ctx);
653 if (err == 0 && user->extra_offset) {
654 char __user *sfp = (char __user *)user->sigframe;
656 apply_user_offset(user, user->extra_offset);
658 struct extra_context __user *extra;
659 struct _aarch64_ctx __user *end;
663 extra = (struct extra_context __user *)userp;
664 userp += EXTRA_CONTEXT_SIZE;
666 end = (struct _aarch64_ctx __user *)userp;
667 userp += TERMINATOR_SIZE;
670 * extra_datap is just written to the signal frame.
671 * The value gets cast back to a void __user *
674 extra_datap = (__force u64)userp;
675 extra_size = sfp + round_up(user->size, 16) - userp;
677 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
678 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
679 __put_user_error(extra_datap, &extra->datap, err);
680 __put_user_error(extra_size, &extra->size, err);
682 /* Add the terminator */
683 __put_user_error(0, &end->magic, err);
684 __put_user_error(0, &end->size, err);
687 /* set the "end" magic */
689 struct _aarch64_ctx __user *end =
690 apply_user_offset(user, user->end_offset);
692 __put_user_error(0, &end->magic, err);
693 __put_user_error(0, &end->size, err);
699 static int get_sigframe(struct rt_sigframe_user_layout *user,
700 struct ksignal *ksig, struct pt_regs *regs)
702 unsigned long sp, sp_top;
705 init_user_layout(user);
706 err = setup_sigframe_layout(user);
710 sp = sp_top = sigsp(regs->sp, ksig);
712 sp = round_down(sp - sizeof(struct frame_record), 16);
713 user->next_frame = (struct frame_record __user *)sp;
715 sp = round_down(sp, 16) - sigframe_size(user);
716 user->sigframe = (struct rt_sigframe __user *)sp;
719 * Check that we can actually write to the signal frame.
721 if (!access_ok(VERIFY_WRITE, user->sigframe, sp_top - sp))
727 static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
728 struct rt_sigframe_user_layout *user, int usig)
730 __sigrestore_t sigtramp;
732 regs->regs[0] = usig;
733 regs->sp = (unsigned long)user->sigframe;
734 regs->regs[29] = (unsigned long)&user->next_frame->fp;
735 regs->pc = (unsigned long)ka->sa.sa_handler;
737 if (ka->sa.sa_flags & SA_RESTORER)
738 sigtramp = ka->sa.sa_restorer;
740 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
742 regs->regs[30] = (unsigned long)sigtramp;
745 static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
746 struct pt_regs *regs)
748 struct rt_sigframe_user_layout user;
749 struct rt_sigframe __user *frame;
752 fpsimd_signal_preserve_current_state();
754 if (get_sigframe(&user, ksig, regs))
757 frame = user.sigframe;
759 __put_user_error(0, &frame->uc.uc_flags, err);
760 __put_user_error(NULL, &frame->uc.uc_link, err);
762 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
763 err |= setup_sigframe(&user, regs, set);
765 setup_return(regs, &ksig->ka, &user, usig);
766 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
767 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
768 regs->regs[1] = (unsigned long)&frame->info;
769 regs->regs[2] = (unsigned long)&frame->uc;
776 static void setup_restart_syscall(struct pt_regs *regs)
778 if (is_compat_task())
779 compat_setup_restart_syscall(regs);
781 regs->regs[8] = __NR_restart_syscall;
785 * OK, we're invoking a handler
787 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
789 struct task_struct *tsk = current;
790 sigset_t *oldset = sigmask_to_save();
791 int usig = ksig->sig;
795 * Set up the stack frame
797 if (is_compat_task()) {
798 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
799 ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
801 ret = compat_setup_frame(usig, ksig, oldset, regs);
803 ret = setup_rt_frame(usig, ksig, oldset, regs);
807 * Check that the resulting registers are actually sane.
809 ret |= !valid_user_regs(®s->user_regs, current);
812 * Fast forward the stepping logic so we step into the signal
816 user_fastforward_single_step(tsk);
818 signal_setup_done(ret, ksig, 0);
822 * Note that 'init' is a special process: it doesn't get signals it doesn't
823 * want to handle. Thus you cannot kill init even with a SIGKILL even by
826 * Note that we go through the signals twice: once to check the signals that
827 * the kernel can handle, and then we build all the user-level signal handling
828 * stack-frames in one go after that.
830 static void do_signal(struct pt_regs *regs)
832 unsigned long continue_addr = 0, restart_addr = 0;
837 * If we were from a system call, check for system call restarting...
839 if (in_syscall(regs)) {
840 continue_addr = regs->pc;
841 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
842 retval = regs->regs[0];
845 * Avoid additional syscall restarting via ret_to_user.
847 forget_syscall(regs);
850 * Prepare for system call restart. We do this here so that a
851 * debugger will see the already changed PC.
854 case -ERESTARTNOHAND:
856 case -ERESTARTNOINTR:
857 case -ERESTART_RESTARTBLOCK:
858 regs->regs[0] = regs->orig_x0;
859 regs->pc = restart_addr;
865 * Get the signal to deliver. When running under ptrace, at this point
866 * the debugger may change all of our registers.
868 if (get_signal(&ksig)) {
870 * Depending on the signal settings, we may need to revert the
871 * decision to restart the system call, but skip this if a
872 * debugger has chosen to restart at a different PC.
874 if (regs->pc == restart_addr &&
875 (retval == -ERESTARTNOHAND ||
876 retval == -ERESTART_RESTARTBLOCK ||
877 (retval == -ERESTARTSYS &&
878 !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
879 regs->regs[0] = -EINTR;
880 regs->pc = continue_addr;
883 handle_signal(&ksig, regs);
888 * Handle restarting a different system call. As above, if a debugger
889 * has chosen to restart at a different PC, ignore the restart.
891 if (in_syscall(regs) && regs->pc == restart_addr) {
892 if (retval == -ERESTART_RESTARTBLOCK)
893 setup_restart_syscall(regs);
894 user_rewind_single_step(current);
897 restore_saved_sigmask();
900 asmlinkage void do_notify_resume(struct pt_regs *regs,
901 unsigned int thread_flags)
904 * The assembly code enters us with IRQs off, but it hasn't
905 * informed the tracing code of that for efficiency reasons.
906 * Update the trace code with the current status.
908 trace_hardirqs_off();
911 /* Check valid user FS if needed */
912 addr_limit_user_check();
914 if (thread_flags & _TIF_NEED_RESCHED) {
915 /* Unmask Debug and SError for the next task */
916 local_daif_restore(DAIF_PROCCTX_NOIRQ);
920 local_daif_restore(DAIF_PROCCTX);
922 if (thread_flags & _TIF_UPROBE)
923 uprobe_notify_resume(regs);
925 if (thread_flags & _TIF_SIGPENDING)
928 if (thread_flags & _TIF_NOTIFY_RESUME) {
929 clear_thread_flag(TIF_NOTIFY_RESUME);
930 tracehook_notify_resume(regs);
933 if (thread_flags & _TIF_FOREIGN_FPSTATE)
934 fpsimd_restore_current_state();
938 thread_flags = READ_ONCE(current_thread_info()->flags);
939 } while (thread_flags & _TIF_WORK_MASK);