Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 981 insertions, 0 deletions

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
new file mode 100644
index 000000000..b6fbbd527
--- /dev/null
+++ b/arch/arm64/kernel/signal.c
@@ -0,0 +1,981 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Based on arch/arm/kernel/signal.c
+ *
+ * Copyright (C) 1995-2009 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ */
+
+#include <linux/cache.h>
+#include <linux/compat.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/personality.h>
+#include <linux/freezer.h>
+#include <linux/stddef.h>
+#include <linux/uaccess.h>
+#include <linux/sizes.h>
+#include <linux/string.h>
+#include <linux/tracehook.h>
+#include <linux/ratelimit.h>
+#include <linux/syscalls.h>
+
+#include <asm/daifflags.h>
+#include <asm/debug-monitors.h>
+#include <asm/elf.h>
+#include <asm/cacheflush.h>
+#include <asm/ucontext.h>
+#include <asm/unistd.h>
+#include <asm/fpsimd.h>
+#include <asm/ptrace.h>
+#include <asm/syscall.h>
+#include <asm/signal32.h>
+#include <asm/traps.h>
+#include <asm/vdso.h>
+
+/*
+ * Do a signal return; undo the signal stack. These are aligned to 128-bit.
+ */
+struct rt_sigframe {
+	struct siginfo info;
+	struct ucontext uc;
+};
+
+struct frame_record {
+	u64 fp;
+	u64 lr;
+};
+
+struct rt_sigframe_user_layout {
+	struct rt_sigframe __user *sigframe;
+	struct frame_record __user *next_frame;
+
+	unsigned long size;	/* size of allocated sigframe data */
+	unsigned long limit;	/* largest allowed size */
+
+	unsigned long fpsimd_offset;
+	unsigned long esr_offset;
+	unsigned long sve_offset;
+	unsigned long extra_offset;
+	unsigned long end_offset;
+};
+
+#define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
+#define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
+#define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
+
+static void init_user_layout(struct rt_sigframe_user_layout *user)
+{
+	const size_t reserved_size =
+		sizeof(user->sigframe->uc.uc_mcontext.__reserved);
+
+	memset(user, 0, sizeof(*user));
+	user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
+
+	user->limit = user->size + reserved_size;
+
+	user->limit -= TERMINATOR_SIZE;
+	user->limit -= EXTRA_CONTEXT_SIZE;
+	/* Reserve space for extension and terminator ^ */
+}
+
+static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
+{
+	return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
+}
+
+/*
+ * Sanity limit on the approximate maximum size of signal frame we'll
+ * try to generate.  Stack alignment padding and the frame record are
+ * not taken into account.  This limit is not a guarantee and is
+ * NOT ABI.
+ */
+#define SIGFRAME_MAXSZ SZ_64K
+
+static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
+			    unsigned long *offset, size_t size, bool extend)
+{
+	size_t padded_size = round_up(size, 16);
+
+	if (padded_size > user->limit - user->size &&
+	    !user->extra_offset &&
+	    extend) {
+		int ret;
+
+		user->limit += EXTRA_CONTEXT_SIZE;
+		ret = __sigframe_alloc(user, &user->extra_offset,
+				       sizeof(struct extra_context), false);
+		if (ret) {
+			user->limit -= EXTRA_CONTEXT_SIZE;
+			return ret;
+		}
+
+		/* Reserve space for the __reserved[] terminator */
+		user->size += TERMINATOR_SIZE;
+
+		/*
+		 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
+		 * the terminator:
+		 */
+		user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
+	}
+
+	/* Still not enough space?  Bad luck! */
+	if (padded_size > user->limit - user->size)
+		return -ENOMEM;
+
+	*offset = user->size;
+	user->size += padded_size;
+
+	return 0;
+}
+
+/*
+ * Allocate space for an optional record of <size> bytes in the user
+ * signal frame.  The offset from the signal frame base address to the
+ * allocated block is assigned to *offset.
+ */
+static int sigframe_alloc(struct rt_sigframe_user_layout *user,
+			  unsigned long *offset, size_t size)
+{
+	return __sigframe_alloc(user, offset, size, true);
+}
+
+/* Allocate the null terminator record and prevent further allocations */
+static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
+{
+	int ret;
+
+	/* Un-reserve the space reserved for the terminator: */
+	user->limit += TERMINATOR_SIZE;
+
+	ret = sigframe_alloc(user, &user->end_offset,
+			     sizeof(struct _aarch64_ctx));
+	if (ret)
+		return ret;
+
+	/* Prevent further allocation: */
+	user->limit = user->size;
+	return 0;
+}
+
+static void __user *apply_user_offset(
+	struct rt_sigframe_user_layout const *user, unsigned long offset)
+{
+	char __user *base = (char __user *)user->sigframe;
+
+	return base + offset;
+}
+
+static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
+{
+	struct user_fpsimd_state const *fpsimd =
+		&current->thread.uw.fpsimd_state;
+	int err;
+
+	/* copy the FP and status/control registers */
+	err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
+	__put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
+	__put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
+
+	/* copy the magic/size information */
+	__put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
+	__put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
+
+	return err ? -EFAULT : 0;
+}
+
+static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
+{
+	struct user_fpsimd_state fpsimd;
+	__u32 magic, size;
+	int err = 0;
+
+	/* check the magic/size information */
+	__get_user_error(magic, &ctx->head.magic, err);
+	__get_user_error(size, &ctx->head.size, err);
+	if (err)
+		return -EFAULT;
+	if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
+		return -EINVAL;
+
+	/* copy the FP and status/control registers */
+	err = __copy_from_user(fpsimd.vregs, ctx->vregs,
+			       sizeof(fpsimd.vregs));
+	__get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
+	__get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
+
+	clear_thread_flag(TIF_SVE);
+
+	/* load the hardware registers from the fpsimd_state structure */
+	if (!err)
+		fpsimd_update_current_state(&fpsimd);
+
+	return err ? -EFAULT : 0;
+}
+
+
+struct user_ctxs {
+	struct fpsimd_context __user *fpsimd;
+	struct sve_context __user *sve;
+};
+
+#ifdef CONFIG_ARM64_SVE
+
+static int preserve_sve_context(struct sve_context __user *ctx)
+{
+	int err = 0;
+	u16 reserved[ARRAY_SIZE(ctx->__reserved)];
+	unsigned int vl = current->thread.sve_vl;
+	unsigned int vq = 0;
+
+	if (test_thread_flag(TIF_SVE))
+		vq = sve_vq_from_vl(vl);
+
+	memset(reserved, 0, sizeof(reserved));
+
+	__put_user_error(SVE_MAGIC, &ctx->head.magic, err);
+	__put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
+			 &ctx->head.size, err);
+	__put_user_error(vl, &ctx->vl, err);
+	BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
+	err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
+
+	if (vq) {
+		/*
+		 * This assumes that the SVE state has already been saved to
+		 * the task struct by calling the function
+		 * fpsimd_signal_preserve_current_state().
+		 */
+		err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
+				      current->thread.sve_state,
+				      SVE_SIG_REGS_SIZE(vq));
+	}
+
+	return err ? -EFAULT : 0;
+}
+
+static int restore_sve_fpsimd_context(struct user_ctxs *user)
+{
+	int err;
+	unsigned int vq;
+	struct user_fpsimd_state fpsimd;
+	struct sve_context sve;
+
+	if (__copy_from_user(&sve, user->sve, sizeof(sve)))
+		return -EFAULT;
+
+	if (sve.vl != current->thread.sve_vl)
+		return -EINVAL;
+
+	if (sve.head.size <= sizeof(*user->sve)) {
+		clear_thread_flag(TIF_SVE);
+		goto fpsimd_only;
+	}
+
+	vq = sve_vq_from_vl(sve.vl);
+
+	if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
+		return -EINVAL;
+
+	/*
+	 * Careful: we are about __copy_from_user() directly into
+	 * thread.sve_state with preemption enabled, so protection is
+	 * needed to prevent a racing context switch from writing stale
+	 * registers back over the new data.
+	 */
+
+	fpsimd_flush_task_state(current);
+	/* From now, fpsimd_thread_switch() won't touch thread.sve_state */
+
+	sve_alloc(current);
+	err = __copy_from_user(current->thread.sve_state,
+			       (char __user const *)user->sve +
+					SVE_SIG_REGS_OFFSET,
+			       SVE_SIG_REGS_SIZE(vq));
+	if (err)
+		return -EFAULT;
+
+	set_thread_flag(TIF_SVE);
+
+fpsimd_only:
+	/* copy the FP and status/control registers */
+	/* restore_sigframe() already checked that user->fpsimd != NULL. */
+	err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
+			       sizeof(fpsimd.vregs));
+	__get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
+	__get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
+
+	/* load the hardware registers from the fpsimd_state structure */
+	if (!err)
+		fpsimd_update_current_state(&fpsimd);
+
+	return err ? -EFAULT : 0;
+}
+
+#else /* ! CONFIG_ARM64_SVE */
+
+/* Turn any non-optimised out attempts to use these into a link error: */
+extern int preserve_sve_context(void __user *ctx);
+extern int restore_sve_fpsimd_context(struct user_ctxs *user);
+
+#endif /* ! CONFIG_ARM64_SVE */
+
+
+static int parse_user_sigframe(struct user_ctxs *user,
+			       struct rt_sigframe __user *sf)
+{
+	struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
+	struct _aarch64_ctx __user *head;
+	char __user *base = (char __user *)&sc->__reserved;
+	size_t offset = 0;
+	size_t limit = sizeof(sc->__reserved);
+	bool have_extra_context = false;
+	char const __user *const sfp = (char const __user *)sf;
+
+	user->fpsimd = NULL;
+	user->sve = NULL;
+
+	if (!IS_ALIGNED((unsigned long)base, 16))
+		goto invalid;
+
+	while (1) {
+		int err = 0;
+		u32 magic, size;
+		char const __user *userp;
+		struct extra_context const __user *extra;
+		u64 extra_datap;
+		u32 extra_size;
+		struct _aarch64_ctx const __user *end;
+		u32 end_magic, end_size;
+
+		if (limit - offset < sizeof(*head))
+			goto invalid;
+
+		if (!IS_ALIGNED(offset, 16))
+			goto invalid;
+
+		head = (struct _aarch64_ctx __user *)(base + offset);
+		__get_user_error(magic, &head->magic, err);
+		__get_user_error(size, &head->size, err);
+		if (err)
+			return err;
+
+		if (limit - offset < size)
+			goto invalid;
+
+		switch (magic) {
+		case 0:
+			if (size)
+				goto invalid;
+
+			goto done;
+
+		case FPSIMD_MAGIC:
+			if (!system_supports_fpsimd())
+				goto invalid;
+			if (user->fpsimd)
+				goto invalid;
+
+			if (size < sizeof(*user->fpsimd))
+				goto invalid;
+
+			user->fpsimd = (struct fpsimd_context __user *)head;
+			break;
+
+		case ESR_MAGIC:
+			/* ignore */
+			break;
+
+		case SVE_MAGIC:
+			if (!system_supports_sve())
+				goto invalid;
+
+			if (user->sve)
+				goto invalid;
+
+			if (size < sizeof(*user->sve))
+				goto invalid;
+
+			user->sve = (struct sve_context __user *)head;
+			break;
+
+		case EXTRA_MAGIC:
+			if (have_extra_context)
+				goto invalid;
+
+			if (size < sizeof(*extra))
+				goto invalid;
+
+			userp = (char const __user *)head;
+
+			extra = (struct extra_context const __user *)userp;
+			userp += size;
+
+			__get_user_error(extra_datap, &extra->datap, err);
+			__get_user_error(extra_size, &extra->size, err);
+			if (err)
+				return err;
+
+			/* Check for the dummy terminator in __reserved[]: */
+
+			if (limit - offset - size < TERMINATOR_SIZE)
+				goto invalid;
+
+			end = (struct _aarch64_ctx const __user *)userp;
+			userp += TERMINATOR_SIZE;
+
+			__get_user_error(end_magic, &end->magic, err);
+			__get_user_error(end_size, &end->size, err);
+			if (err)
+				return err;
+
+			if (end_magic || end_size)
+				goto invalid;
+
+			/* Prevent looping/repeated parsing of extra_context */
+			have_extra_context = true;
+
+			base = (__force void __user *)extra_datap;
+			if (!IS_ALIGNED((unsigned long)base, 16))
+				goto invalid;
+
+			if (!IS_ALIGNED(extra_size, 16))
+				goto invalid;
+
+			if (base != userp)
+				goto invalid;
+
+			/* Reject "unreasonably large" frames: */
+			if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
+				goto invalid;
+
+			/*
+			 * Ignore trailing terminator in __reserved[]
+			 * and start parsing extra data:
+			 */
+			offset = 0;
+			limit = extra_size;
+
+			if (!access_ok(base, limit))
+				goto invalid;
+
+			continue;
+
+		default:
+			goto invalid;
+		}
+
+		if (size < sizeof(*head))
+			goto invalid;
+
+		if (limit - offset < size)
+			goto invalid;
+
+		offset += size;
+	}
+
+done:
+	return 0;
+
+invalid:
+	return -EINVAL;
+}
+
+static int restore_sigframe(struct pt_regs *regs,
+			    struct rt_sigframe __user *sf)
+{
+	sigset_t set;
+	int i, err;
+	struct user_ctxs user;
+
+	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
+	if (err == 0)
+		set_current_blocked(&set);
+
+	for (i = 0; i < 31; i++)
+		__get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
+				 err);
+	__get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
+	__get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
+	__get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
+
+	/*
+	 * Avoid sys_rt_sigreturn() restarting.
+	 */
+	forget_syscall(regs);
+
+	err |= !valid_user_regs(&regs->user_regs, current);
+	if (err == 0)
+		err = parse_user_sigframe(&user, sf);
+
+	if (err == 0 && system_supports_fpsimd()) {
+		if (!user.fpsimd)
+			return -EINVAL;
+
+		if (user.sve) {
+			if (!system_supports_sve())
+				return -EINVAL;
+
+			err = restore_sve_fpsimd_context(&user);
+		} else {
+			err = restore_fpsimd_context(user.fpsimd);
+		}
+	}
+
+	return err;
+}
+
+SYSCALL_DEFINE0(rt_sigreturn)
+{
+	struct pt_regs *regs = current_pt_regs();
+	struct rt_sigframe __user *frame;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->restart_block.fn = do_no_restart_syscall;
+
+	/*
+	 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
+	 * be word aligned here.
+	 */
+	if (regs->sp & 15)
+		goto badframe;
+
+	frame = (struct rt_sigframe __user *)regs->sp;
+
+	if (!access_ok(frame, sizeof (*frame)))
+		goto badframe;
+
+	if (restore_sigframe(regs, frame))
+		goto badframe;
+
+	if (restore_altstack(&frame->uc.uc_stack))
+		goto badframe;
+
+	return regs->regs[0];
+
+badframe:
+	arm64_notify_segfault(regs->sp);
+	return 0;
+}
+
+/*
+ * Determine the layout of optional records in the signal frame
+ *
+ * add_all: if true, lays out the biggest possible signal frame for
+ *	this task; otherwise, generates a layout for the current state
+ *	of the task.
+ */
+static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
+				 bool add_all)
+{
+	int err;
+
+	if (system_supports_fpsimd()) {
+		err = sigframe_alloc(user, &user->fpsimd_offset,
+				     sizeof(struct fpsimd_context));
+		if (err)
+			return err;
+	}
+
+	/* fault information, if valid */
+	if (add_all || current->thread.fault_code) {
+		err = sigframe_alloc(user, &user->esr_offset,
+				     sizeof(struct esr_context));
+		if (err)
+			return err;
+	}
+
+	if (system_supports_sve()) {
+		unsigned int vq = 0;
+
+		if (add_all || test_thread_flag(TIF_SVE)) {
+			int vl = sve_max_vl;
+
+			if (!add_all)
+				vl = current->thread.sve_vl;
+
+			vq = sve_vq_from_vl(vl);
+		}
+
+		err = sigframe_alloc(user, &user->sve_offset,
+				     SVE_SIG_CONTEXT_SIZE(vq));
+		if (err)
+			return err;
+	}
+
+	return sigframe_alloc_end(user);
+}
+
+static int setup_sigframe(struct rt_sigframe_user_layout *user,
+			  struct pt_regs *regs, sigset_t *set)
+{
+	int i, err = 0;
+	struct rt_sigframe __user *sf = user->sigframe;
+
+	/* set up the stack frame for unwinding */
+	__put_user_error(regs->regs[29], &user->next_frame->fp, err);
+	__put_user_error(regs->regs[30], &user->next_frame->lr, err);
+
+	for (i = 0; i < 31; i++)
+		__put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
+				 err);
+	__put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
+	__put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
+	__put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
+
+	__put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
+
+	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
+
+	if (err == 0 && system_supports_fpsimd()) {
+		struct fpsimd_context __user *fpsimd_ctx =
+			apply_user_offset(user, user->fpsimd_offset);
+		err |= preserve_fpsimd_context(fpsimd_ctx);
+	}
+
+	/* fault information, if valid */
+	if (err == 0 && user->esr_offset) {
+		struct esr_context __user *esr_ctx =
+			apply_user_offset(user, user->esr_offset);
+
+		__put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
+		__put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
+		__put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
+	}
+
+	/* Scalable Vector Extension state, if present */
+	if (system_supports_sve() && err == 0 && user->sve_offset) {
+		struct sve_context __user *sve_ctx =
+			apply_user_offset(user, user->sve_offset);
+		err |= preserve_sve_context(sve_ctx);
+	}
+
+	if (err == 0 && user->extra_offset) {
+		char __user *sfp = (char __user *)user->sigframe;
+		char __user *userp =
+			apply_user_offset(user, user->extra_offset);
+
+		struct extra_context __user *extra;
+		struct _aarch64_ctx __user *end;
+		u64 extra_datap;
+		u32 extra_size;
+
+		extra = (struct extra_context __user *)userp;
+		userp += EXTRA_CONTEXT_SIZE;
+
+		end = (struct _aarch64_ctx __user *)userp;
+		userp += TERMINATOR_SIZE;
+
+		/*
+		 * extra_datap is just written to the signal frame.
+		 * The value gets cast back to a void __user *
+		 * during sigreturn.
+		 */
+		extra_datap = (__force u64)userp;
+		extra_size = sfp + round_up(user->size, 16) - userp;
+
+		__put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
+		__put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
+		__put_user_error(extra_datap, &extra->datap, err);
+		__put_user_error(extra_size, &extra->size, err);
+
+		/* Add the terminator */
+		__put_user_error(0, &end->magic, err);
+		__put_user_error(0, &end->size, err);
+	}
+
+	/* set the "end" magic */
+	if (err == 0) {
+		struct _aarch64_ctx __user *end =
+			apply_user_offset(user, user->end_offset);
+
+		__put_user_error(0, &end->magic, err);
+		__put_user_error(0, &end->size, err);
+	}
+
+	return err;
+}
+
+static int get_sigframe(struct rt_sigframe_user_layout *user,
+			 struct ksignal *ksig, struct pt_regs *regs)
+{
+	unsigned long sp, sp_top;
+	int err;
+
+	init_user_layout(user);
+	err = setup_sigframe_layout(user, false);
+	if (err)
+		return err;
+
+	sp = sp_top = sigsp(regs->sp, ksig);
+
+	sp = round_down(sp - sizeof(struct frame_record), 16);
+	user->next_frame = (struct frame_record __user *)sp;
+
+	sp = round_down(sp, 16) - sigframe_size(user);
+	user->sigframe = (struct rt_sigframe __user *)sp;
+
+	/*
+	 * Check that we can actually write to the signal frame.
+	 */
+	if (!access_ok(user->sigframe, sp_top - sp))
+		return -EFAULT;
+
+	return 0;
+}
+
+static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
+			 struct rt_sigframe_user_layout *user, int usig)
+{
+	__sigrestore_t sigtramp;
+
+	regs->regs[0] = usig;
+	regs->sp = (unsigned long)user->sigframe;
+	regs->regs[29] = (unsigned long)&user->next_frame->fp;
+	regs->pc = (unsigned long)ka->sa.sa_handler;
+
+	/*
+	 * Signal delivery is a (wacky) indirect function call in
+	 * userspace, so simulate the same setting of BTYPE as a BLR
+	 * <register containing the signal handler entry point>.
+	 * Signal delivery to a location in a PROT_BTI guarded page
+	 * that is not a function entry point will now trigger a
+	 * SIGILL in userspace.
+	 *
+	 * If the signal handler entry point is not in a PROT_BTI
+	 * guarded page, this is harmless.
+	 */
+	if (system_supports_bti()) {
+		regs->pstate &= ~PSR_BTYPE_MASK;
+		regs->pstate |= PSR_BTYPE_C;
+	}
+
+	/* TCO (Tag Check Override) always cleared for signal handlers */
+	regs->pstate &= ~PSR_TCO_BIT;
+
+	if (ka->sa.sa_flags & SA_RESTORER)
+		sigtramp = ka->sa.sa_restorer;
+	else
+		sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
+
+	regs->regs[30] = (unsigned long)sigtramp;
+}
+
+static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
+			  struct pt_regs *regs)
+{
+	struct rt_sigframe_user_layout user;
+	struct rt_sigframe __user *frame;
+	int err = 0;
+
+	fpsimd_signal_preserve_current_state();
+
+	if (get_sigframe(&user, ksig, regs))
+		return 1;
+
+	frame = user.sigframe;
+
+	__put_user_error(0, &frame->uc.uc_flags, err);
+	__put_user_error(NULL, &frame->uc.uc_link, err);
+
+	err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
+	err |= setup_sigframe(&user, regs, set);
+	if (err == 0) {
+		setup_return(regs, &ksig->ka, &user, usig);
+		if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+			err |= copy_siginfo_to_user(&frame->info, &ksig->info);
+			regs->regs[1] = (unsigned long)&frame->info;
+			regs->regs[2] = (unsigned long)&frame->uc;
+		}
+	}
+
+	return err;
+}
+
+static void setup_restart_syscall(struct pt_regs *regs)
+{
+	if (is_compat_task())
+		compat_setup_restart_syscall(regs);
+	else
+		regs->regs[8] = __NR_restart_syscall;
+}
+
+/*
+ * OK, we're invoking a handler
+ */
+static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
+{
+	sigset_t *oldset = sigmask_to_save();
+	int usig = ksig->sig;
+	int ret;
+
+	rseq_signal_deliver(ksig, regs);
+
+	/*
+	 * Set up the stack frame
+	 */
+	if (is_compat_task()) {
+		if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+			ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
+		else
+			ret = compat_setup_frame(usig, ksig, oldset, regs);
+	} else {
+		ret = setup_rt_frame(usig, ksig, oldset, regs);
+	}
+
+	/*
+	 * Check that the resulting registers are actually sane.
+	 */
+	ret |= !valid_user_regs(&regs->user_regs, current);
+
+	/* Step into the signal handler if we are stepping */
+	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
+}
+
+/*
+ * Note that 'init' is a special process: it doesn't get signals it doesn't
+ * want to handle. Thus you cannot kill init even with a SIGKILL even by
+ * mistake.
+ *
+ * Note that we go through the signals twice: once to check the signals that
+ * the kernel can handle, and then we build all the user-level signal handling
+ * stack-frames in one go after that.
+ */
+static void do_signal(struct pt_regs *regs)
+{
+	unsigned long continue_addr = 0, restart_addr = 0;
+	int retval = 0;
+	struct ksignal ksig;
+	bool syscall = in_syscall(regs);
+
+	/*
+	 * If we were from a system call, check for system call restarting...
+	 */
+	if (syscall) {
+		continue_addr = regs->pc;
+		restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
+		retval = regs->regs[0];
+
+		/*
+		 * Avoid additional syscall restarting via ret_to_user.
+		 */
+		forget_syscall(regs);
+
+		/*
+		 * Prepare for system call restart. We do this here so that a
+		 * debugger will see the already changed PC.
+		 */
+		switch (retval) {
+		case -ERESTARTNOHAND:
+		case -ERESTARTSYS:
+		case -ERESTARTNOINTR:
+		case -ERESTART_RESTARTBLOCK:
+			regs->regs[0] = regs->orig_x0;
+			regs->pc = restart_addr;
+			break;
+		}
+	}
+
+	/*
+	 * Get the signal to deliver. When running under ptrace, at this point
+	 * the debugger may change all of our registers.
+	 */
+	if (get_signal(&ksig)) {
+		/*
+		 * Depending on the signal settings, we may need to revert the
+		 * decision to restart the system call, but skip this if a
+		 * debugger has chosen to restart at a different PC.
+		 */
+		if (regs->pc == restart_addr &&
+		    (retval == -ERESTARTNOHAND ||
+		     retval == -ERESTART_RESTARTBLOCK ||
+		     (retval == -ERESTARTSYS &&
+		      !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
+			syscall_set_return_value(current, regs, -EINTR, 0);
+			regs->pc = continue_addr;
+		}
+
+		handle_signal(&ksig, regs);
+		return;
+	}
+
+	/*
+	 * Handle restarting a different system call. As above, if a debugger
+	 * has chosen to restart at a different PC, ignore the restart.
+	 */
+	if (syscall && regs->pc == restart_addr) {
+		if (retval == -ERESTART_RESTARTBLOCK)
+			setup_restart_syscall(regs);
+		user_rewind_single_step(current);
+	}
+
+	restore_saved_sigmask();
+}
+
+asmlinkage void do_notify_resume(struct pt_regs *regs,
+				 unsigned long thread_flags)
+{
+	do {
+		/* Check valid user FS if needed */
+		addr_limit_user_check();
+
+		if (thread_flags & _TIF_NEED_RESCHED) {
+			/* Unmask Debug and SError for the next task */
+			local_daif_restore(DAIF_PROCCTX_NOIRQ);
+
+			schedule();
+		} else {
+			local_daif_restore(DAIF_PROCCTX);
+
+			if (thread_flags & _TIF_UPROBE)
+				uprobe_notify_resume(regs);
+
+			if (thread_flags & _TIF_MTE_ASYNC_FAULT) {
+				clear_thread_flag(TIF_MTE_ASYNC_FAULT);
+				send_sig_fault(SIGSEGV, SEGV_MTEAERR,
+					       (void __user *)NULL, current);
+			}
+
+			if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
+				do_signal(regs);
+
+			if (thread_flags & _TIF_NOTIFY_RESUME) {
+				tracehook_notify_resume(regs);
+				rseq_handle_notify_resume(NULL, regs);
+			}
+
+			if (thread_flags & _TIF_FOREIGN_FPSTATE)
+				fpsimd_restore_current_state();
+		}
+
+		local_daif_mask();
+		thread_flags = READ_ONCE(current_thread_info()->flags);
+	} while (thread_flags & _TIF_WORK_MASK);
+}
+
+unsigned long __ro_after_init signal_minsigstksz;
+
+/*
+ * Determine the stack space required for guaranteed signal devliery.
+ * This function is used to populate AT_MINSIGSTKSZ at process startup.
+ * cpufeatures setup is assumed to be complete.
+ */
+void __init minsigstksz_setup(void)
+{
+	struct rt_sigframe_user_layout user;
+
+	init_user_layout(&user);
+
+	/*
+	 * If this fails, SIGFRAME_MAXSZ needs to be enlarged.  It won't
+	 * be big enough, but it's our best guess:
+	 */
+	if (WARN_ON(setup_sigframe_layout(&user, true)))
+		return;
+
+	signal_minsigstksz = sigframe_size(&user) +
+		round_up(sizeof(struct frame_record), 16) +
+		16; /* max alignment padding */
+}