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>
43 #include <asm/traps.h>
47 * Do a signal return; undo the signal stack. These are aligned to 128-bit.
59 struct rt_sigframe_user_layout {
60 struct rt_sigframe __user *sigframe;
61 struct frame_record __user *next_frame;
63 unsigned long size; /* size of allocated sigframe data */
64 unsigned long limit; /* largest allowed size */
66 unsigned long fpsimd_offset;
67 unsigned long esr_offset;
68 unsigned long sve_offset;
69 unsigned long extra_offset;
70 unsigned long end_offset;
73 #define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
74 #define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
75 #define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
77 static void init_user_layout(struct rt_sigframe_user_layout *user)
79 const size_t reserved_size =
80 sizeof(user->sigframe->uc.uc_mcontext.__reserved);
82 memset(user, 0, sizeof(*user));
83 user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
85 user->limit = user->size + reserved_size;
87 user->limit -= TERMINATOR_SIZE;
88 user->limit -= EXTRA_CONTEXT_SIZE;
89 /* Reserve space for extension and terminator ^ */
92 static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
94 return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
98 * Sanity limit on the approximate maximum size of signal frame we'll
99 * try to generate. Stack alignment padding and the frame record are
100 * not taken into account. This limit is not a guarantee and is
103 #define SIGFRAME_MAXSZ SZ_64K
105 static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
106 unsigned long *offset, size_t size, bool extend)
108 size_t padded_size = round_up(size, 16);
110 if (padded_size > user->limit - user->size &&
111 !user->extra_offset &&
115 user->limit += EXTRA_CONTEXT_SIZE;
116 ret = __sigframe_alloc(user, &user->extra_offset,
117 sizeof(struct extra_context), false);
119 user->limit -= EXTRA_CONTEXT_SIZE;
123 /* Reserve space for the __reserved[] terminator */
124 user->size += TERMINATOR_SIZE;
127 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
130 user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
133 /* Still not enough space? Bad luck! */
134 if (padded_size > user->limit - user->size)
137 *offset = user->size;
138 user->size += padded_size;
144 * Allocate space for an optional record of <size> bytes in the user
145 * signal frame. The offset from the signal frame base address to the
146 * allocated block is assigned to *offset.
148 static int sigframe_alloc(struct rt_sigframe_user_layout *user,
149 unsigned long *offset, size_t size)
151 return __sigframe_alloc(user, offset, size, true);
154 /* Allocate the null terminator record and prevent further allocations */
155 static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
159 /* Un-reserve the space reserved for the terminator: */
160 user->limit += TERMINATOR_SIZE;
162 ret = sigframe_alloc(user, &user->end_offset,
163 sizeof(struct _aarch64_ctx));
167 /* Prevent further allocation: */
168 user->limit = user->size;
172 static void __user *apply_user_offset(
173 struct rt_sigframe_user_layout const *user, unsigned long offset)
175 char __user *base = (char __user *)user->sigframe;
177 return base + offset;
180 static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
182 struct user_fpsimd_state const *fpsimd =
183 ¤t->thread.uw.fpsimd_state;
186 /* copy the FP and status/control registers */
187 err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
188 __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
189 __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
191 /* copy the magic/size information */
192 __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
193 __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
195 return err ? -EFAULT : 0;
198 static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
200 struct user_fpsimd_state fpsimd;
204 /* check the magic/size information */
205 __get_user_error(magic, &ctx->head.magic, err);
206 __get_user_error(size, &ctx->head.size, err);
209 if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
212 /* copy the FP and status/control registers */
213 err = __copy_from_user(fpsimd.vregs, ctx->vregs,
214 sizeof(fpsimd.vregs));
215 __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
216 __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
218 clear_thread_flag(TIF_SVE);
220 /* load the hardware registers from the fpsimd_state structure */
222 fpsimd_update_current_state(&fpsimd);
224 return err ? -EFAULT : 0;
229 struct fpsimd_context __user *fpsimd;
230 struct sve_context __user *sve;
233 #ifdef CONFIG_ARM64_SVE
235 static int preserve_sve_context(struct sve_context __user *ctx)
238 u16 reserved[ARRAY_SIZE(ctx->__reserved)];
239 unsigned int vl = current->thread.sve_vl;
242 if (test_thread_flag(TIF_SVE))
243 vq = sve_vq_from_vl(vl);
245 memset(reserved, 0, sizeof(reserved));
247 __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
248 __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
249 &ctx->head.size, err);
250 __put_user_error(vl, &ctx->vl, err);
251 BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
252 err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
256 * This assumes that the SVE state has already been saved to
257 * the task struct by calling preserve_fpsimd_context().
259 err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
260 current->thread.sve_state,
261 SVE_SIG_REGS_SIZE(vq));
264 return err ? -EFAULT : 0;
267 static int restore_sve_fpsimd_context(struct user_ctxs *user)
271 struct user_fpsimd_state fpsimd;
272 struct sve_context sve;
274 if (__copy_from_user(&sve, user->sve, sizeof(sve)))
277 if (sve.vl != current->thread.sve_vl)
280 if (sve.head.size <= sizeof(*user->sve)) {
281 clear_thread_flag(TIF_SVE);
285 vq = sve_vq_from_vl(sve.vl);
287 if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
291 * Careful: we are about __copy_from_user() directly into
292 * thread.sve_state with preemption enabled, so protection is
293 * needed to prevent a racing context switch from writing stale
294 * registers back over the new data.
297 fpsimd_flush_task_state(current);
299 /* From now, fpsimd_thread_switch() won't clear TIF_FOREIGN_FPSTATE */
301 set_thread_flag(TIF_FOREIGN_FPSTATE);
303 /* From now, fpsimd_thread_switch() won't touch thread.sve_state */
306 err = __copy_from_user(current->thread.sve_state,
307 (char __user const *)user->sve +
309 SVE_SIG_REGS_SIZE(vq));
313 set_thread_flag(TIF_SVE);
316 /* copy the FP and status/control registers */
317 /* restore_sigframe() already checked that user->fpsimd != NULL. */
318 err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
319 sizeof(fpsimd.vregs));
320 __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
321 __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
323 /* load the hardware registers from the fpsimd_state structure */
325 fpsimd_update_current_state(&fpsimd);
327 return err ? -EFAULT : 0;
330 #else /* ! CONFIG_ARM64_SVE */
332 /* Turn any non-optimised out attempts to use these into a link error: */
333 extern int preserve_sve_context(void __user *ctx);
334 extern int restore_sve_fpsimd_context(struct user_ctxs *user);
336 #endif /* ! CONFIG_ARM64_SVE */
339 static int parse_user_sigframe(struct user_ctxs *user,
340 struct rt_sigframe __user *sf)
342 struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
343 struct _aarch64_ctx __user *head;
344 char __user *base = (char __user *)&sc->__reserved;
346 size_t limit = sizeof(sc->__reserved);
347 bool have_extra_context = false;
348 char const __user *const sfp = (char const __user *)sf;
353 if (!IS_ALIGNED((unsigned long)base, 16))
359 char const __user *userp;
360 struct extra_context const __user *extra;
363 struct _aarch64_ctx const __user *end;
364 u32 end_magic, end_size;
366 if (limit - offset < sizeof(*head))
369 if (!IS_ALIGNED(offset, 16))
372 head = (struct _aarch64_ctx __user *)(base + offset);
373 __get_user_error(magic, &head->magic, err);
374 __get_user_error(size, &head->size, err);
378 if (limit - offset < size)
392 if (size < sizeof(*user->fpsimd))
395 user->fpsimd = (struct fpsimd_context __user *)head;
403 if (!system_supports_sve())
409 if (size < sizeof(*user->sve))
412 user->sve = (struct sve_context __user *)head;
416 if (have_extra_context)
419 if (size < sizeof(*extra))
422 userp = (char const __user *)head;
424 extra = (struct extra_context const __user *)userp;
427 __get_user_error(extra_datap, &extra->datap, err);
428 __get_user_error(extra_size, &extra->size, err);
432 /* Check for the dummy terminator in __reserved[]: */
434 if (limit - offset - size < TERMINATOR_SIZE)
437 end = (struct _aarch64_ctx const __user *)userp;
438 userp += TERMINATOR_SIZE;
440 __get_user_error(end_magic, &end->magic, err);
441 __get_user_error(end_size, &end->size, err);
445 if (end_magic || end_size)
448 /* Prevent looping/repeated parsing of extra_context */
449 have_extra_context = true;
451 base = (__force void __user *)extra_datap;
452 if (!IS_ALIGNED((unsigned long)base, 16))
455 if (!IS_ALIGNED(extra_size, 16))
461 /* Reject "unreasonably large" frames: */
462 if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
466 * Ignore trailing terminator in __reserved[]
467 * and start parsing extra data:
472 if (!access_ok(VERIFY_READ, base, limit))
481 if (size < sizeof(*head))
484 if (limit - offset < size)
497 static int restore_sigframe(struct pt_regs *regs,
498 struct rt_sigframe __user *sf)
502 struct user_ctxs user;
504 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
506 set_current_blocked(&set);
508 for (i = 0; i < 31; i++)
509 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
511 __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
512 __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
513 __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
516 * Avoid sys_rt_sigreturn() restarting.
518 forget_syscall(regs);
520 err |= !valid_user_regs(®s->user_regs, current);
522 err = parse_user_sigframe(&user, sf);
529 if (!system_supports_sve())
532 err = restore_sve_fpsimd_context(&user);
534 err = restore_fpsimd_context(user.fpsimd);
541 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
543 struct rt_sigframe __user *frame;
545 /* Always make any pending restarted system calls return -EINTR */
546 current->restart_block.fn = do_no_restart_syscall;
549 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
550 * be word aligned here.
555 frame = (struct rt_sigframe __user *)regs->sp;
557 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
560 if (restore_sigframe(regs, frame))
563 if (restore_altstack(&frame->uc.uc_stack))
566 return regs->regs[0];
569 arm64_notify_segfault(regs->sp);
573 /* Determine the layout of optional records in the signal frame */
574 static int setup_sigframe_layout(struct rt_sigframe_user_layout *user)
578 err = sigframe_alloc(user, &user->fpsimd_offset,
579 sizeof(struct fpsimd_context));
583 /* fault information, if valid */
584 if (current->thread.fault_code) {
585 err = sigframe_alloc(user, &user->esr_offset,
586 sizeof(struct esr_context));
591 if (system_supports_sve()) {
594 if (test_thread_flag(TIF_SVE))
595 vq = sve_vq_from_vl(current->thread.sve_vl);
597 err = sigframe_alloc(user, &user->sve_offset,
598 SVE_SIG_CONTEXT_SIZE(vq));
603 return sigframe_alloc_end(user);
607 static int setup_sigframe(struct rt_sigframe_user_layout *user,
608 struct pt_regs *regs, sigset_t *set)
611 struct rt_sigframe __user *sf = user->sigframe;
613 /* set up the stack frame for unwinding */
614 __put_user_error(regs->regs[29], &user->next_frame->fp, err);
615 __put_user_error(regs->regs[30], &user->next_frame->lr, err);
617 for (i = 0; i < 31; i++)
618 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
620 __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
621 __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
622 __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
624 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
626 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
629 struct fpsimd_context __user *fpsimd_ctx =
630 apply_user_offset(user, user->fpsimd_offset);
631 err |= preserve_fpsimd_context(fpsimd_ctx);
634 /* fault information, if valid */
635 if (err == 0 && user->esr_offset) {
636 struct esr_context __user *esr_ctx =
637 apply_user_offset(user, user->esr_offset);
639 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
640 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
641 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
644 /* Scalable Vector Extension state, if present */
645 if (system_supports_sve() && err == 0 && user->sve_offset) {
646 struct sve_context __user *sve_ctx =
647 apply_user_offset(user, user->sve_offset);
648 err |= preserve_sve_context(sve_ctx);
651 if (err == 0 && user->extra_offset) {
652 char __user *sfp = (char __user *)user->sigframe;
654 apply_user_offset(user, user->extra_offset);
656 struct extra_context __user *extra;
657 struct _aarch64_ctx __user *end;
661 extra = (struct extra_context __user *)userp;
662 userp += EXTRA_CONTEXT_SIZE;
664 end = (struct _aarch64_ctx __user *)userp;
665 userp += TERMINATOR_SIZE;
668 * extra_datap is just written to the signal frame.
669 * The value gets cast back to a void __user *
672 extra_datap = (__force u64)userp;
673 extra_size = sfp + round_up(user->size, 16) - userp;
675 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
676 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
677 __put_user_error(extra_datap, &extra->datap, err);
678 __put_user_error(extra_size, &extra->size, err);
680 /* Add the terminator */
681 __put_user_error(0, &end->magic, err);
682 __put_user_error(0, &end->size, err);
685 /* set the "end" magic */
687 struct _aarch64_ctx __user *end =
688 apply_user_offset(user, user->end_offset);
690 __put_user_error(0, &end->magic, err);
691 __put_user_error(0, &end->size, err);
697 static int get_sigframe(struct rt_sigframe_user_layout *user,
698 struct ksignal *ksig, struct pt_regs *regs)
700 unsigned long sp, sp_top;
703 init_user_layout(user);
704 err = setup_sigframe_layout(user);
708 sp = sp_top = sigsp(regs->sp, ksig);
710 sp = round_down(sp - sizeof(struct frame_record), 16);
711 user->next_frame = (struct frame_record __user *)sp;
713 sp = round_down(sp, 16) - sigframe_size(user);
714 user->sigframe = (struct rt_sigframe __user *)sp;
717 * Check that we can actually write to the signal frame.
719 if (!access_ok(VERIFY_WRITE, user->sigframe, sp_top - sp))
725 static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
726 struct rt_sigframe_user_layout *user, int usig)
728 __sigrestore_t sigtramp;
730 regs->regs[0] = usig;
731 regs->sp = (unsigned long)user->sigframe;
732 regs->regs[29] = (unsigned long)&user->next_frame->fp;
733 regs->pc = (unsigned long)ka->sa.sa_handler;
735 if (ka->sa.sa_flags & SA_RESTORER)
736 sigtramp = ka->sa.sa_restorer;
738 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
740 regs->regs[30] = (unsigned long)sigtramp;
743 static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
744 struct pt_regs *regs)
746 struct rt_sigframe_user_layout user;
747 struct rt_sigframe __user *frame;
750 fpsimd_signal_preserve_current_state();
752 if (get_sigframe(&user, ksig, regs))
755 frame = user.sigframe;
757 __put_user_error(0, &frame->uc.uc_flags, err);
758 __put_user_error(NULL, &frame->uc.uc_link, err);
760 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
761 err |= setup_sigframe(&user, regs, set);
763 setup_return(regs, &ksig->ka, &user, usig);
764 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
765 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
766 regs->regs[1] = (unsigned long)&frame->info;
767 regs->regs[2] = (unsigned long)&frame->uc;
774 static void setup_restart_syscall(struct pt_regs *regs)
776 if (is_compat_task())
777 compat_setup_restart_syscall(regs);
779 regs->regs[8] = __NR_restart_syscall;
783 * OK, we're invoking a handler
785 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
787 struct task_struct *tsk = current;
788 sigset_t *oldset = sigmask_to_save();
789 int usig = ksig->sig;
793 * Set up the stack frame
795 if (is_compat_task()) {
796 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
797 ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
799 ret = compat_setup_frame(usig, ksig, oldset, regs);
801 ret = setup_rt_frame(usig, ksig, oldset, regs);
805 * Check that the resulting registers are actually sane.
807 ret |= !valid_user_regs(®s->user_regs, current);
810 * Fast forward the stepping logic so we step into the signal
814 user_fastforward_single_step(tsk);
816 signal_setup_done(ret, ksig, 0);
820 * Note that 'init' is a special process: it doesn't get signals it doesn't
821 * want to handle. Thus you cannot kill init even with a SIGKILL even by
824 * Note that we go through the signals twice: once to check the signals that
825 * the kernel can handle, and then we build all the user-level signal handling
826 * stack-frames in one go after that.
828 static void do_signal(struct pt_regs *regs)
830 unsigned long continue_addr = 0, restart_addr = 0;
835 * If we were from a system call, check for system call restarting...
837 if (in_syscall(regs)) {
838 continue_addr = regs->pc;
839 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
840 retval = regs->regs[0];
843 * Avoid additional syscall restarting via ret_to_user.
845 forget_syscall(regs);
848 * Prepare for system call restart. We do this here so that a
849 * debugger will see the already changed PC.
852 case -ERESTARTNOHAND:
854 case -ERESTARTNOINTR:
855 case -ERESTART_RESTARTBLOCK:
856 regs->regs[0] = regs->orig_x0;
857 regs->pc = restart_addr;
863 * Get the signal to deliver. When running under ptrace, at this point
864 * the debugger may change all of our registers.
866 if (get_signal(&ksig)) {
868 * Depending on the signal settings, we may need to revert the
869 * decision to restart the system call, but skip this if a
870 * debugger has chosen to restart at a different PC.
872 if (regs->pc == restart_addr &&
873 (retval == -ERESTARTNOHAND ||
874 retval == -ERESTART_RESTARTBLOCK ||
875 (retval == -ERESTARTSYS &&
876 !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
877 regs->regs[0] = -EINTR;
878 regs->pc = continue_addr;
881 handle_signal(&ksig, regs);
886 * Handle restarting a different system call. As above, if a debugger
887 * has chosen to restart at a different PC, ignore the restart.
889 if (in_syscall(regs) && regs->pc == restart_addr) {
890 if (retval == -ERESTART_RESTARTBLOCK)
891 setup_restart_syscall(regs);
892 user_rewind_single_step(current);
895 restore_saved_sigmask();
898 asmlinkage void do_notify_resume(struct pt_regs *regs,
899 unsigned int thread_flags)
902 * The assembly code enters us with IRQs off, but it hasn't
903 * informed the tracing code of that for efficiency reasons.
904 * Update the trace code with the current status.
906 trace_hardirqs_off();
909 /* Check valid user FS if needed */
910 addr_limit_user_check();
912 if (thread_flags & _TIF_NEED_RESCHED) {
913 /* Unmask Debug and SError for the next task */
914 local_daif_restore(DAIF_PROCCTX_NOIRQ);
918 local_daif_restore(DAIF_PROCCTX);
920 if (thread_flags & _TIF_UPROBE)
921 uprobe_notify_resume(regs);
923 if (thread_flags & _TIF_SIGPENDING)
926 if (thread_flags & _TIF_NOTIFY_RESUME) {
927 clear_thread_flag(TIF_NOTIFY_RESUME);
928 tracehook_notify_resume(regs);
931 if (thread_flags & _TIF_FOREIGN_FPSTATE)
932 fpsimd_restore_current_state();
936 thread_flags = READ_ONCE(current_thread_info()->flags);
937 } while (thread_flags & _TIF_WORK_MASK);