1 files changed, 306 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/signal_common.h b/arch/arm64/include/asm/signal_common.h
new file mode 100644
index 000000000000..84abe973e8b3
--- /dev/null
+++ b/arch/arm64/include/asm/signal_common.h
@@ -0,0 +1,306 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+/*
+ * Copyright (C) 1995-2009 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ * Copyright (C) 2018 Cavium Networks.
+ */
+
+#ifndef __ASM_SIGNAL_COMMON_H
+#define __ASM_SIGNAL_COMMON_H
+
+#include <linux/uaccess.h>
+#include <asm/fpsimd.h>
+
+#define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
+#define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
+#define SIGCONTEXT_RESERVED_SIZE sizeof(((struct sigcontext *)0)->__reserved)
+#define RT_SIGFRAME_RESERVED_OFFSET \
+		offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved)
+
+/*
+ * 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
+
+struct rt_sigframe_user_layout {
+	void __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;
+};
+
+struct user_ctxs {
+	struct fpsimd_context __user *fpsimd;
+	struct sve_context __user *sve;
+};
+
+struct frame_record {
+	u64 fp;
+	u64 lr;
+};
+
+void __user *apply_user_offset(struct rt_sigframe_user_layout const *user,
+			       unsigned long offset);
+
+int setup_sigframe_layout(struct rt_sigframe_user_layout *user);
+int setup_extra_context(char __user *sfp, unsigned long sf_size,
+			char __user *exprap);
+int __parse_user_sigcontext(struct user_ctxs *user,
+				   struct sigcontext __user const *sc,
+				   void __user const *sigframe_base);
+#define parse_user_sigcontext(user, sf)					\
+	__parse_user_sigcontext(user, &(sf)->uc.uc_mcontext, sf)
+
+int preserve_fpsimd_context(struct fpsimd_context __user *ctx);
+int restore_fpsimd_context(struct fpsimd_context __user *ctx);
+
+#ifdef CONFIG_ARM64_SVE
+int preserve_sve_context(struct sve_context __user *ctx);
+int restore_sve_fpsimd_context(struct user_ctxs *user);
+#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 */
+
+int sigframe_alloc(struct rt_sigframe_user_layout *user,
+		   unsigned long *offset, size_t size);
+int sigframe_alloc_end(struct rt_sigframe_user_layout *user);
+
+void __setup_return(struct pt_regs *regs, struct k_sigaction *ka,
+		    struct rt_sigframe_user_layout *user, int usig);
+
+static void init_user_layout(struct rt_sigframe_user_layout *user)
+{
+	memset(user, 0, sizeof(*user));
+	user->size = RT_SIGFRAME_RESERVED_OFFSET;
+
+	user->limit = user->size + SIGCONTEXT_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);
+}
+
+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);
+	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 = (void __user *)sp;
+
+	/*
+	 * Check that we can actually write to the signal frame.
+	 */
+	if (!access_ok(VERIFY_WRITE, user->sigframe, sp_top - sp))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int restore_sigframe(struct pt_regs *regs,
+			    struct rt_sigframe __user *sf)
+{
+	sigset_t set;
+	int i, err;
+	struct user_ctxs user;
+
+	err = get_sigset(&set, &sf->uc.uc_sigmask);
+	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_sigcontext(&user, sf);
+
+	if (err == 0) {
+		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;
+}
+
+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 |= put_sigset(set, &sf->uc.uc_sigmask);
+
+	if (err == 0) {
+		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)
+		setup_extra_context((char __user *)user->sigframe, user->size,
+				    (char __user *)apply_user_offset(user,
+						   user->extra_offset));
+
+	/* 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 long __sys_rt_sigreturn(struct pt_regs *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(VERIFY_READ, 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:
+	if (show_unhandled_signals)
+		pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
+				    current->comm, task_pid_nr(current), __func__,
+				    regs->pc, regs->sp);
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+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((typeof(frame->uc.uc_link)) 0,
+			  &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;
+}
+
+#endif /* __ASM_SIGNAL_COMMON_H */