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 = ¤t->thread.fpsimd_state;
185 /* copy the FP and status/control registers */
186 err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
187 __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
188 __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
190 /* copy the magic/size information */
191 __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
192 __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
194 return err ? -EFAULT : 0;
197 static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
199 struct user_fpsimd_state fpsimd;
203 /* check the magic/size information */
204 __get_user_error(magic, &ctx->head.magic, err);
205 __get_user_error(size, &ctx->head.size, err);
208 if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
211 /* copy the FP and status/control registers */
212 err = __copy_from_user(fpsimd.vregs, ctx->vregs,
213 sizeof(fpsimd.vregs));
214 __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
215 __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
217 clear_thread_flag(TIF_SVE);
219 /* load the hardware registers from the fpsimd_state structure */
221 fpsimd_update_current_state(&fpsimd);
223 return err ? -EFAULT : 0;
228 struct fpsimd_context __user *fpsimd;
229 struct sve_context __user *sve;
232 #ifdef CONFIG_ARM64_SVE
234 static int preserve_sve_context(struct sve_context __user *ctx)
237 u16 reserved[ARRAY_SIZE(ctx->__reserved)];
238 unsigned int vl = current->thread.sve_vl;
241 if (test_thread_flag(TIF_SVE))
242 vq = sve_vq_from_vl(vl);
244 memset(reserved, 0, sizeof(reserved));
246 __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
247 __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
248 &ctx->head.size, err);
249 __put_user_error(vl, &ctx->vl, err);
250 BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
251 err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
255 * This assumes that the SVE state has already been saved to
256 * the task struct by calling preserve_fpsimd_context().
258 err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
259 current->thread.sve_state,
260 SVE_SIG_REGS_SIZE(vq));
263 return err ? -EFAULT : 0;
266 static int restore_sve_fpsimd_context(struct user_ctxs *user)
270 struct user_fpsimd_state fpsimd;
271 struct sve_context sve;
273 if (__copy_from_user(&sve, user->sve, sizeof(sve)))
276 if (sve.vl != current->thread.sve_vl)
279 if (sve.head.size <= sizeof(*user->sve)) {
280 clear_thread_flag(TIF_SVE);
284 vq = sve_vq_from_vl(sve.vl);
286 if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
290 * Careful: we are about __copy_from_user() directly into
291 * thread.sve_state with preemption enabled, so protection is
292 * needed to prevent a racing context switch from writing stale
293 * registers back over the new data.
296 fpsimd_flush_task_state(current);
298 /* From now, fpsimd_thread_switch() won't clear TIF_FOREIGN_FPSTATE */
300 set_thread_flag(TIF_FOREIGN_FPSTATE);
302 /* From now, fpsimd_thread_switch() won't touch thread.sve_state */
305 err = __copy_from_user(current->thread.sve_state,
306 (char __user const *)user->sve +
308 SVE_SIG_REGS_SIZE(vq));
312 set_thread_flag(TIF_SVE);
315 /* copy the FP and status/control registers */
316 /* restore_sigframe() already checked that user->fpsimd != NULL. */
317 err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
318 sizeof(fpsimd.vregs));
319 __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
320 __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
322 /* load the hardware registers from the fpsimd_state structure */
324 fpsimd_update_current_state(&fpsimd);
326 return err ? -EFAULT : 0;
329 #else /* ! CONFIG_ARM64_SVE */
331 /* Turn any non-optimised out attempts to use these into a link error: */
332 extern int preserve_sve_context(void __user *ctx);
333 extern int restore_sve_fpsimd_context(struct user_ctxs *user);
335 #endif /* ! CONFIG_ARM64_SVE */
338 static int parse_user_sigframe(struct user_ctxs *user,
339 struct rt_sigframe __user *sf)
341 struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
342 struct _aarch64_ctx __user *head;
343 char __user *base = (char __user *)&sc->__reserved;
345 size_t limit = sizeof(sc->__reserved);
346 bool have_extra_context = false;
347 char const __user *const sfp = (char const __user *)sf;
352 if (!IS_ALIGNED((unsigned long)base, 16))
358 char const __user *userp;
359 struct extra_context const __user *extra;
362 struct _aarch64_ctx const __user *end;
363 u32 end_magic, end_size;
365 if (limit - offset < sizeof(*head))
368 if (!IS_ALIGNED(offset, 16))
371 head = (struct _aarch64_ctx __user *)(base + offset);
372 __get_user_error(magic, &head->magic, err);
373 __get_user_error(size, &head->size, err);
377 if (limit - offset < size)
391 if (size < sizeof(*user->fpsimd))
394 user->fpsimd = (struct fpsimd_context __user *)head;
402 if (!system_supports_sve())
408 if (size < sizeof(*user->sve))
411 user->sve = (struct sve_context __user *)head;
415 if (have_extra_context)
418 if (size < sizeof(*extra))
421 userp = (char const __user *)head;
423 extra = (struct extra_context const __user *)userp;
426 __get_user_error(extra_datap, &extra->datap, err);
427 __get_user_error(extra_size, &extra->size, err);
431 /* Check for the dummy terminator in __reserved[]: */
433 if (limit - offset - size < TERMINATOR_SIZE)
436 end = (struct _aarch64_ctx const __user *)userp;
437 userp += TERMINATOR_SIZE;
439 __get_user_error(end_magic, &end->magic, err);
440 __get_user_error(end_size, &end->size, err);
444 if (end_magic || end_size)
447 /* Prevent looping/repeated parsing of extra_context */
448 have_extra_context = true;
450 base = (__force void __user *)extra_datap;
451 if (!IS_ALIGNED((unsigned long)base, 16))
454 if (!IS_ALIGNED(extra_size, 16))
460 /* Reject "unreasonably large" frames: */
461 if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
465 * Ignore trailing terminator in __reserved[]
466 * and start parsing extra data:
471 if (!access_ok(VERIFY_READ, base, limit))
480 if (size < sizeof(*head))
483 if (limit - offset < size)
496 static int restore_sigframe(struct pt_regs *regs,
497 struct rt_sigframe __user *sf)
501 struct user_ctxs user;
503 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
505 set_current_blocked(&set);
507 for (i = 0; i < 31; i++)
508 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
510 __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
511 __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
512 __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
515 * Avoid sys_rt_sigreturn() restarting.
517 forget_syscall(regs);
519 err |= !valid_user_regs(®s->user_regs, current);
521 err = parse_user_sigframe(&user, sf);
528 if (!system_supports_sve())
531 err = restore_sve_fpsimd_context(&user);
533 err = restore_fpsimd_context(user.fpsimd);
540 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
542 struct rt_sigframe __user *frame;
544 /* Always make any pending restarted system calls return -EINTR */
545 current->restart_block.fn = do_no_restart_syscall;
548 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
549 * be word aligned here.
554 frame = (struct rt_sigframe __user *)regs->sp;
556 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
559 if (restore_sigframe(regs, frame))
562 if (restore_altstack(&frame->uc.uc_stack))
565 return regs->regs[0];
568 arm64_notify_segfault(regs->sp);
572 /* Determine the layout of optional records in the signal frame */
573 static int setup_sigframe_layout(struct rt_sigframe_user_layout *user)
577 err = sigframe_alloc(user, &user->fpsimd_offset,
578 sizeof(struct fpsimd_context));
582 /* fault information, if valid */
583 if (current->thread.fault_code) {
584 err = sigframe_alloc(user, &user->esr_offset,
585 sizeof(struct esr_context));
590 if (system_supports_sve()) {
593 if (test_thread_flag(TIF_SVE))
594 vq = sve_vq_from_vl(current->thread.sve_vl);
596 err = sigframe_alloc(user, &user->sve_offset,
597 SVE_SIG_CONTEXT_SIZE(vq));
602 return sigframe_alloc_end(user);
606 static int setup_sigframe(struct rt_sigframe_user_layout *user,
607 struct pt_regs *regs, sigset_t *set)
610 struct rt_sigframe __user *sf = user->sigframe;
612 /* set up the stack frame for unwinding */
613 __put_user_error(regs->regs[29], &user->next_frame->fp, err);
614 __put_user_error(regs->regs[30], &user->next_frame->lr, err);
616 for (i = 0; i < 31; i++)
617 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
619 __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
620 __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
621 __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
623 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
625 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
628 struct fpsimd_context __user *fpsimd_ctx =
629 apply_user_offset(user, user->fpsimd_offset);
630 err |= preserve_fpsimd_context(fpsimd_ctx);
633 /* fault information, if valid */
634 if (err == 0 && user->esr_offset) {
635 struct esr_context __user *esr_ctx =
636 apply_user_offset(user, user->esr_offset);
638 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
639 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
640 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
643 /* Scalable Vector Extension state, if present */
644 if (system_supports_sve() && err == 0 && user->sve_offset) {
645 struct sve_context __user *sve_ctx =
646 apply_user_offset(user, user->sve_offset);
647 err |= preserve_sve_context(sve_ctx);
650 if (err == 0 && user->extra_offset) {
651 char __user *sfp = (char __user *)user->sigframe;
653 apply_user_offset(user, user->extra_offset);
655 struct extra_context __user *extra;
656 struct _aarch64_ctx __user *end;
660 extra = (struct extra_context __user *)userp;
661 userp += EXTRA_CONTEXT_SIZE;
663 end = (struct _aarch64_ctx __user *)userp;
664 userp += TERMINATOR_SIZE;
667 * extra_datap is just written to the signal frame.
668 * The value gets cast back to a void __user *
671 extra_datap = (__force u64)userp;
672 extra_size = sfp + round_up(user->size, 16) - userp;
674 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
675 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
676 __put_user_error(extra_datap, &extra->datap, err);
677 __put_user_error(extra_size, &extra->size, err);
679 /* Add the terminator */
680 __put_user_error(0, &end->magic, err);
681 __put_user_error(0, &end->size, err);
684 /* set the "end" magic */
686 struct _aarch64_ctx __user *end =
687 apply_user_offset(user, user->end_offset);
689 __put_user_error(0, &end->magic, err);
690 __put_user_error(0, &end->size, err);
696 static int get_sigframe(struct rt_sigframe_user_layout *user,
697 struct ksignal *ksig, struct pt_regs *regs)
699 unsigned long sp, sp_top;
702 init_user_layout(user);
703 err = setup_sigframe_layout(user);
707 sp = sp_top = sigsp(regs->sp, ksig);
709 sp = round_down(sp - sizeof(struct frame_record), 16);
710 user->next_frame = (struct frame_record __user *)sp;
712 sp = round_down(sp, 16) - sigframe_size(user);
713 user->sigframe = (struct rt_sigframe __user *)sp;
716 * Check that we can actually write to the signal frame.
718 if (!access_ok(VERIFY_WRITE, user->sigframe, sp_top - sp))
724 static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
725 struct rt_sigframe_user_layout *user, int usig)
727 __sigrestore_t sigtramp;
729 regs->regs[0] = usig;
730 regs->sp = (unsigned long)user->sigframe;
731 regs->regs[29] = (unsigned long)&user->next_frame->fp;
732 regs->pc = (unsigned long)ka->sa.sa_handler;
734 if (ka->sa.sa_flags & SA_RESTORER)
735 sigtramp = ka->sa.sa_restorer;
737 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
739 regs->regs[30] = (unsigned long)sigtramp;
742 static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
743 struct pt_regs *regs)
745 struct rt_sigframe_user_layout user;
746 struct rt_sigframe __user *frame;
749 fpsimd_signal_preserve_current_state();
751 if (get_sigframe(&user, ksig, regs))
754 frame = user.sigframe;
756 __put_user_error(0, &frame->uc.uc_flags, err);
757 __put_user_error(NULL, &frame->uc.uc_link, err);
759 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
760 err |= setup_sigframe(&user, regs, set);
762 setup_return(regs, &ksig->ka, &user, usig);
763 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
764 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
765 regs->regs[1] = (unsigned long)&frame->info;
766 regs->regs[2] = (unsigned long)&frame->uc;
773 static void setup_restart_syscall(struct pt_regs *regs)
775 if (is_compat_task())
776 compat_setup_restart_syscall(regs);
778 regs->regs[8] = __NR_restart_syscall;
782 * OK, we're invoking a handler
784 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
786 struct task_struct *tsk = current;
787 sigset_t *oldset = sigmask_to_save();
788 int usig = ksig->sig;
792 * Set up the stack frame
794 if (is_compat_task()) {
795 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
796 ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
798 ret = compat_setup_frame(usig, ksig, oldset, regs);
800 ret = setup_rt_frame(usig, ksig, oldset, regs);
804 * Check that the resulting registers are actually sane.
806 ret |= !valid_user_regs(®s->user_regs, current);
809 * Fast forward the stepping logic so we step into the signal
813 user_fastforward_single_step(tsk);
815 signal_setup_done(ret, ksig, 0);
819 * Note that 'init' is a special process: it doesn't get signals it doesn't
820 * want to handle. Thus you cannot kill init even with a SIGKILL even by
823 * Note that we go through the signals twice: once to check the signals that
824 * the kernel can handle, and then we build all the user-level signal handling
825 * stack-frames in one go after that.
827 static void do_signal(struct pt_regs *regs)
829 unsigned long continue_addr = 0, restart_addr = 0;
834 * If we were from a system call, check for system call restarting...
836 if (in_syscall(regs)) {
837 continue_addr = regs->pc;
838 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
839 retval = regs->regs[0];
842 * Avoid additional syscall restarting via ret_to_user.
844 forget_syscall(regs);
847 * Prepare for system call restart. We do this here so that a
848 * debugger will see the already changed PC.
851 case -ERESTARTNOHAND:
853 case -ERESTARTNOINTR:
854 case -ERESTART_RESTARTBLOCK:
855 regs->regs[0] = regs->orig_x0;
856 regs->pc = restart_addr;
862 * Get the signal to deliver. When running under ptrace, at this point
863 * the debugger may change all of our registers.
865 if (get_signal(&ksig)) {
867 * Depending on the signal settings, we may need to revert the
868 * decision to restart the system call, but skip this if a
869 * debugger has chosen to restart at a different PC.
871 if (regs->pc == restart_addr &&
872 (retval == -ERESTARTNOHAND ||
873 retval == -ERESTART_RESTARTBLOCK ||
874 (retval == -ERESTARTSYS &&
875 !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
876 regs->regs[0] = -EINTR;
877 regs->pc = continue_addr;
880 handle_signal(&ksig, regs);
885 * Handle restarting a different system call. As above, if a debugger
886 * has chosen to restart at a different PC, ignore the restart.
888 if (in_syscall(regs) && regs->pc == restart_addr) {
889 if (retval == -ERESTART_RESTARTBLOCK)
890 setup_restart_syscall(regs);
891 user_rewind_single_step(current);
894 restore_saved_sigmask();
897 asmlinkage void do_notify_resume(struct pt_regs *regs,
898 unsigned int thread_flags)
901 * The assembly code enters us with IRQs off, but it hasn't
902 * informed the tracing code of that for efficiency reasons.
903 * Update the trace code with the current status.
905 trace_hardirqs_off();
908 /* Check valid user FS if needed */
909 addr_limit_user_check();
911 if (thread_flags & _TIF_NEED_RESCHED) {
912 /* Unmask Debug and SError for the next task */
913 local_daif_restore(DAIF_PROCCTX_NOIRQ);
917 local_daif_restore(DAIF_PROCCTX);
919 if (thread_flags & _TIF_UPROBE)
920 uprobe_notify_resume(regs);
922 if (thread_flags & _TIF_SIGPENDING)
925 if (thread_flags & _TIF_NOTIFY_RESUME) {
926 clear_thread_flag(TIF_NOTIFY_RESUME);
927 tracehook_notify_resume(regs);
930 if (thread_flags & _TIF_FOREIGN_FPSTATE)
931 fpsimd_restore_current_state();
935 thread_flags = READ_ONCE(current_thread_info()->flags);
936 } while (thread_flags & _TIF_WORK_MASK);