arch/riscv/kernel/signal.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
  *  Chen Liqin <liqin.chen@sunplusct.com>
  *  Lennox Wu <lennox.wu@sunplusct.com>
  * Copyright (C) 2012 Regents of the University of California
  */

 #include <linux/compat.h>
 #include <linux/signal.h>
 #include <linux/uaccess.h>
 #include <linux/syscalls.h>
 #include <linux/resume_user_mode.h>
 #include <linux/linkage.h>
 #include <linux/entry-common.h>

 #include <asm/ucontext.h>
 #include <asm/vdso.h>
 #include <asm/signal.h>
 #include <asm/signal32.h>
 #include <asm/switch_to.h>
 #include <asm/vector.h>
 #include <asm/csr.h>
 #include <asm/cacheflush.h>

 unsigned long signal_minsigstksz __ro_after_init;

 extern u32 __user_rt_sigreturn[2];
 static size_t riscv_v_sc_size __ro_after_init;

 #define DEBUG_SIG 0

 struct rt_sigframe {
 	struct siginfo info;
 	struct ucontext uc;
 #ifndef CONFIG_MMU
 	u32 sigreturn_code[2];
 #endif
 };

 #ifdef CONFIG_FPU
 static long restore_fp_state(struct pt_regs *regs,
 			     union __riscv_fp_state __user *sc_fpregs)
 {
 	long err;
 	struct __riscv_d_ext_state __user *state = &sc_fpregs->d;

 	err = __copy_from_user(&current->thread.fstate, state, sizeof(*state));
 	if (unlikely(err))
 		return err;

 	fstate_restore(current, regs);
 	return 0;
 }

 static long save_fp_state(struct pt_regs *regs,
 			  union __riscv_fp_state __user *sc_fpregs)
 {
 	long err;
 	struct __riscv_d_ext_state __user *state = &sc_fpregs->d;

 	fstate_save(current, regs);
 	err = __copy_to_user(state, &current->thread.fstate, sizeof(*state));
 	return err;
 }
 #else
 #define save_fp_state(task, regs) (0)
 #define restore_fp_state(task, regs) (0)
 #endif

 #ifdef CONFIG_RISCV_ISA_V

 static long save_v_state(struct pt_regs *regs, void __user **sc_vec)
 {
 	struct __riscv_ctx_hdr __user *hdr;
 	struct __sc_riscv_v_state __user *state;
 	void __user *datap;
 	long err;

 	hdr = *sc_vec;
 	/* Place state to the user's signal context space after the hdr */
 	state = (struct __sc_riscv_v_state __user *)(hdr + 1);
 	/* Point datap right after the end of __sc_riscv_v_state */
 	datap = state + 1;

 	/* datap is designed to be 16 byte aligned for better performance */
 	WARN_ON(unlikely(!IS_ALIGNED((unsigned long)datap, 16)));

 	get_cpu_vector_context();
 	riscv_v_vstate_save(&current->thread.vstate, regs);
 	put_cpu_vector_context();

 	/* Copy everything of vstate but datap. */
 	err = __copy_to_user(&state->v_state, &current->thread.vstate,
 			     offsetof(struct __riscv_v_ext_state, datap));
 	/* Copy the pointer datap itself. */
 	err |= __put_user((__force void *)datap, &state->v_state.datap);
 	/* Copy the whole vector content to user space datap. */
 	err |= __copy_to_user(datap, current->thread.vstate.datap, riscv_v_vsize);
 	/* Copy magic to the user space after saving  all vector conetext */
 	err |= __put_user(RISCV_V_MAGIC, &hdr->magic);
 	err |= __put_user(riscv_v_sc_size, &hdr->size);
 	if (unlikely(err))
 		return err;

 	/* Only progress the sv_vec if everything has done successfully  */
 	*sc_vec += riscv_v_sc_size;
 	return 0;
 }

 /*
  * Restore Vector extension context from the user's signal frame. This function
  * assumes a valid extension header. So magic and size checking must be done by
  * the caller.
  */
 static long __restore_v_state(struct pt_regs *regs, void __user *sc_vec)
 {
 	long err;
 	struct __sc_riscv_v_state __user *state = sc_vec;
 	void __user *datap;

 	/* Copy everything of __sc_riscv_v_state except datap. */
 	err = __copy_from_user(&current->thread.vstate, &state->v_state,
 			       offsetof(struct __riscv_v_ext_state, datap));
 	if (unlikely(err))
 		return err;

 	/* Copy the pointer datap itself. */
 	err = __get_user(datap, &state->v_state.datap);
 	if (unlikely(err))
 		return err;
 	/*
 	 * Copy the whole vector content from user space datap. Use
 	 * copy_from_user to prevent information leak.
 	 */
 	err = copy_from_user(current->thread.vstate.datap, datap, riscv_v_vsize);
 	if (unlikely(err))
 		return err;

 	riscv_v_vstate_set_restore(current, regs);

 	return err;
 }
 #else
 #define save_v_state(task, regs) (0)
 #define __restore_v_state(task, regs) (0)
 #endif

 static long restore_sigcontext(struct pt_regs *regs,
 	struct sigcontext __user *sc)
 {
 	void __user *sc_ext_ptr = &sc->sc_extdesc.hdr;
 	__u32 rsvd;
 	long err;
 	/* sc_regs is structured the same as the start of pt_regs */
 	err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
 	if (unlikely(err))
 		return err;

 	/* Restore the floating-point state. */
 	if (has_fpu()) {
 		err = restore_fp_state(regs, &sc->sc_fpregs);
 		if (unlikely(err))
 			return err;
 	}

 	/* Check the reserved word before extensions parsing */
 	err = __get_user(rsvd, &sc->sc_extdesc.reserved);
 	if (unlikely(err))
 		return err;
 	if (unlikely(rsvd))
 		return -EINVAL;

 	while (!err) {
 		__u32 magic, size;
 		struct __riscv_ctx_hdr __user *head = sc_ext_ptr;

 		err |= __get_user(magic, &head->magic);
 		err |= __get_user(size, &head->size);
 		if (unlikely(err))
 			return err;

 		sc_ext_ptr += sizeof(*head);
 		switch (magic) {
 		case END_MAGIC:
 			if (size != END_HDR_SIZE)
 				return -EINVAL;

 			return 0;
 		case RISCV_V_MAGIC:
 			if (!has_vector() || !riscv_v_vstate_query(regs) ||
 			    size != riscv_v_sc_size)
 				return -EINVAL;

 			err = __restore_v_state(regs, sc_ext_ptr);
 			break;
 		default:
 			return -EINVAL;
 		}
 		sc_ext_ptr = (void __user *)head + size;
 	}
 	return err;
 }

 static size_t get_rt_frame_size(bool cal_all)
 {
 	struct rt_sigframe __user *frame;
 	size_t frame_size;
 	size_t total_context_size = 0;

 	frame_size = sizeof(*frame);

 	if (has_vector()) {
 		if (cal_all || riscv_v_vstate_query(task_pt_regs(current)))
 			total_context_size += riscv_v_sc_size;
 	}
 	/*
 	 * Preserved a __riscv_ctx_hdr for END signal context header if an
 	 * extension uses __riscv_extra_ext_header
 	 */
 	if (total_context_size)
 		total_context_size += sizeof(struct __riscv_ctx_hdr);

 	frame_size += total_context_size;

 	frame_size = round_up(frame_size, 16);
 	return frame_size;
 }

 SYSCALL_DEFINE0(rt_sigreturn)
 {
 	struct pt_regs *regs = current_pt_regs();
 	struct rt_sigframe __user *frame;
 	struct task_struct *task;
 	sigset_t set;
 	size_t frame_size = get_rt_frame_size(false);

 	/* Always make any pending restarted system calls return -EINTR */
 	current->restart_block.fn = do_no_restart_syscall;

 	frame = (struct rt_sigframe __user *)regs->sp;

 	if (!access_ok(frame, frame_size))
 		goto badframe;

 	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 		goto badframe;

 	set_current_blocked(&set);

 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 		goto badframe;

 	if (restore_altstack(&frame->uc.uc_stack))
 		goto badframe;

 	regs->cause = -1UL;

 	return regs->a0;

 badframe:
 	task = current;
 	if (show_unhandled_signals) {
 		pr_info_ratelimited(
 			"%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
 			task->comm, task_pid_nr(task), __func__,
 			frame, (void *)regs->epc, (void *)regs->sp);
 	}
 	force_sig(SIGSEGV);
 	return 0;
 }

 static long setup_sigcontext(struct rt_sigframe __user *frame,
 	struct pt_regs *regs)
 {
 	struct sigcontext __user *sc = &frame->uc.uc_mcontext;
 	struct __riscv_ctx_hdr __user *sc_ext_ptr = &sc->sc_extdesc.hdr;
 	long err;

 	/* sc_regs is structured the same as the start of pt_regs */
 	err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
 	/* Save the floating-point state. */
 	if (has_fpu())
 		err |= save_fp_state(regs, &sc->sc_fpregs);
 	/* Save the vector state. */
 	if (has_vector() && riscv_v_vstate_query(regs))
 		err |= save_v_state(regs, (void __user **)&sc_ext_ptr);
 	/* Write zero to fp-reserved space and check it on restore_sigcontext */
 	err |= __put_user(0, &sc->sc_extdesc.reserved);
 	/* And put END __riscv_ctx_hdr at the end. */
 	err |= __put_user(END_MAGIC, &sc_ext_ptr->magic);
 	err |= __put_user(END_HDR_SIZE, &sc_ext_ptr->size);

 	return err;
 }

 static inline void __user *get_sigframe(struct ksignal *ksig,
 	struct pt_regs *regs, size_t framesize)
 {
 	unsigned long sp;
 	/* Default to using normal stack */
 	sp = regs->sp;

 	/*
 	 * If we are on the alternate signal stack and would overflow it, don't.
 	 * Return an always-bogus address instead so we will die with SIGSEGV.
 	 */
 	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
 		return (void __user __force *)(-1UL);

 	/* This is the X/Open sanctioned signal stack switching. */
 	sp = sigsp(sp, ksig) - framesize;

 	/* Align the stack frame. */
 	sp &= ~0xfUL;

 	return (void __user *)sp;
 }

 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 	struct pt_regs *regs)
 {
 	struct rt_sigframe __user *frame;
 	long err = 0;
 	unsigned long __maybe_unused addr;
 	size_t frame_size = get_rt_frame_size(false);

 	frame = get_sigframe(ksig, regs, frame_size);
 	if (!access_ok(frame, frame_size))
 		return -EFAULT;

 	err |= copy_siginfo_to_user(&frame->info, &ksig->info);

 	/* Create the ucontext. */
 	err |= __put_user(0, &frame->uc.uc_flags);
 	err |= __put_user(NULL, &frame->uc.uc_link);
 	err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 	err |= setup_sigcontext(frame, regs);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 	if (err)
 		return -EFAULT;

 	/* Set up to return from userspace. */
 #ifdef CONFIG_MMU
 	regs->ra = (unsigned long)VDSO_SYMBOL(
 		current->mm->context.vdso, rt_sigreturn);
 #else
 	/*
 	 * For the nommu case we don't have a VDSO.  Instead we push two
 	 * instructions to call the rt_sigreturn syscall onto the user stack.
 	 */
 	if (copy_to_user(&frame->sigreturn_code, __user_rt_sigreturn,
 			 sizeof(frame->sigreturn_code)))
 		return -EFAULT;

 	addr = (unsigned long)&frame->sigreturn_code;
 	/* Make sure the two instructions are pushed to icache. */
 	flush_icache_range(addr, addr + sizeof(frame->sigreturn_code));

 	regs->ra = addr;
 #endif /* CONFIG_MMU */

 	/*
 	 * Set up registers for signal handler.
 	 * Registers that we don't modify keep the value they had from
 	 * user-space at the time we took the signal.
 	 * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 	 * since some things rely on this (e.g. glibc's debug/segfault.c).
 	 */
 	regs->epc = (unsigned long)ksig->ka.sa.sa_handler;
 	regs->sp = (unsigned long)frame;
 	regs->a0 = ksig->sig;                     /* a0: signal number */
 	regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */
 	regs->a2 = (unsigned long)(&frame->uc);   /* a2: ucontext pointer */

 #if DEBUG_SIG
 	pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n",
 		current->comm, task_pid_nr(current), ksig->sig,
 		(void *)regs->epc, (void *)regs->ra, frame);
 #endif

 	return 0;
 }

 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 {
 	sigset_t *oldset = sigmask_to_save();
 	int ret;

 	rseq_signal_deliver(ksig, regs);

 	/* Set up the stack frame */
 	if (is_compat_task())
 		ret = compat_setup_rt_frame(ksig, oldset, regs);
 	else
 		ret = setup_rt_frame(ksig, oldset, regs);

 	signal_setup_done(ret, ksig, 0);
 }

 void arch_do_signal_or_restart(struct pt_regs *regs)
 {
 	unsigned long continue_addr = 0, restart_addr = 0;
 	int retval = 0;
 	struct ksignal ksig;
 	bool syscall = (regs->cause == EXC_SYSCALL);

 	/* If we were from a system call, check for system call restarting */
 	if (syscall) {
 		continue_addr = regs->epc;
 		restart_addr = continue_addr - 4;
 		retval = regs->a0;

 		/* Avoid additional syscall restarting via ret_from_exception */
 		regs->cause = -1UL;

 		/*
 		 * 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->a0 = regs->orig_a0;
 			regs->epc = 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->epc == restart_addr &&
 		    (retval == -ERESTARTNOHAND ||
 		     retval == -ERESTART_RESTARTBLOCK ||
 		     (retval == -ERESTARTSYS &&
 		      !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
 			regs->a0 = -EINTR;
 			regs->epc = continue_addr;
 		}

 		/* Actually deliver the signal */
 		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->epc == restart_addr && retval == -ERESTART_RESTARTBLOCK)
 		regs->a7 = __NR_restart_syscall;

 	/*
 	 * If there is no signal to deliver, we just put the saved
 	 * sigmask back.
 	 */
 	restore_saved_sigmask();
 }

 void init_rt_signal_env(void);
 void __init init_rt_signal_env(void)
 {
 	riscv_v_sc_size = sizeof(struct __riscv_ctx_hdr) +
 			  sizeof(struct __sc_riscv_v_state) + riscv_v_vsize;
 	/*
 	 * Determine the stack space required for guaranteed signal delivery.
 	 * The signal_minsigstksz will be populated into the AT_MINSIGSTKSZ entry
 	 * in the auxiliary array at process startup.
 	 */
 	signal_minsigstksz = get_rt_frame_size(true);
 }

 #ifdef CONFIG_DYNAMIC_SIGFRAME
 bool sigaltstack_size_valid(size_t ss_size)
 {
 	return ss_size > get_rt_frame_size(false);
 }
 #endif /* CONFIG_DYNAMIC_SIGFRAME */
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
	* Chen Liqin <liqin.chen@sunplusct.com>
	* Lennox Wu <lennox.wu@sunplusct.com>
	* Copyright (C) 2012 Regents of the University of California
	*/

	#include <linux/compat.h>
	#include <linux/signal.h>
	#include <linux/uaccess.h>
	#include <linux/syscalls.h>
	#include <linux/resume_user_mode.h>
	#include <linux/linkage.h>
	#include <linux/entry-common.h>

	#include <asm/ucontext.h>
	#include <asm/vdso.h>
	#include <asm/signal.h>
	#include <asm/signal32.h>
	#include <asm/switch_to.h>
	#include <asm/vector.h>
	#include <asm/csr.h>
	#include <asm/cacheflush.h>

	unsigned long signal_minsigstksz __ro_after_init;

	extern u32 __user_rt_sigreturn[2];
	static size_t riscv_v_sc_size __ro_after_init;

	#define DEBUG_SIG 0

	struct rt_sigframe {
	struct siginfo info;
	struct ucontext uc;
	#ifndef CONFIG_MMU
	u32 sigreturn_code[2];
	#endif
	};

	#ifdef CONFIG_FPU
	static long restore_fp_state(struct pt_regs *regs,
	union __riscv_fp_state __user *sc_fpregs)
	{
	long err;
	struct __riscv_d_ext_state __user *state = &sc_fpregs->d;

	err = __copy_from_user(&current->thread.fstate, state, sizeof(*state));
	if (unlikely(err))
	return err;

	fstate_restore(current, regs);
	return 0;
	}

	static long save_fp_state(struct pt_regs *regs,
	union __riscv_fp_state __user *sc_fpregs)
	{
	long err;
	struct __riscv_d_ext_state __user *state = &sc_fpregs->d;

	fstate_save(current, regs);
	err = __copy_to_user(state, &current->thread.fstate, sizeof(*state));
	return err;
	}
	#else
	#define save_fp_state(task, regs) (0)
	#define restore_fp_state(task, regs) (0)
	#endif

	#ifdef CONFIG_RISCV_ISA_V

	static long save_v_state(struct pt_regs regs, void __user *sc_vec)
	{
	struct __riscv_ctx_hdr __user *hdr;
	struct __sc_riscv_v_state __user *state;
	void __user *datap;
	long err;

	hdr = *sc_vec;
	/* Place state to the user's signal context space after the hdr */
	state = (struct __sc_riscv_v_state __user *)(hdr + 1);
	/* Point datap right after the end of __sc_riscv_v_state */
	datap = state + 1;

	/* datap is designed to be 16 byte aligned for better performance */
	WARN_ON(unlikely(!IS_ALIGNED((unsigned long)datap, 16)));

	get_cpu_vector_context();
	riscv_v_vstate_save(&current->thread.vstate, regs);
	put_cpu_vector_context();

	/* Copy everything of vstate but datap. */
	err = __copy_to_user(&state->v_state, &current->thread.vstate,
	offsetof(struct __riscv_v_ext_state, datap));
	/* Copy the pointer datap itself. */
	err \|= __put_user((__force void *)datap, &state->v_state.datap);
	/* Copy the whole vector content to user space datap. */
	err \|= __copy_to_user(datap, current->thread.vstate.datap, riscv_v_vsize);
	/* Copy magic to the user space after saving all vector conetext */
	err \|= __put_user(RISCV_V_MAGIC, &hdr->magic);
	err \|= __put_user(riscv_v_sc_size, &hdr->size);
	if (unlikely(err))
	return err;

	/* Only progress the sv_vec if everything has done successfully */
	*sc_vec += riscv_v_sc_size;
	return 0;
	}

	/*
	* Restore Vector extension context from the user's signal frame. This function
	* assumes a valid extension header. So magic and size checking must be done by
	* the caller.
	*/
	static long __restore_v_state(struct pt_regs regs, void __user sc_vec)
	{
	long err;
	struct __sc_riscv_v_state __user *state = sc_vec;
	void __user *datap;

	/* Copy everything of __sc_riscv_v_state except datap. */
	err = __copy_from_user(&current->thread.vstate, &state->v_state,
	offsetof(struct __riscv_v_ext_state, datap));
	if (unlikely(err))
	return err;

	/* Copy the pointer datap itself. */
	err = __get_user(datap, &state->v_state.datap);
	if (unlikely(err))
	return err;
	/*
	* Copy the whole vector content from user space datap. Use
	* copy_from_user to prevent information leak.
	*/
	err = copy_from_user(current->thread.vstate.datap, datap, riscv_v_vsize);
	if (unlikely(err))
	return err;

	riscv_v_vstate_set_restore(current, regs);

	return err;
	}
	#else
	#define save_v_state(task, regs) (0)
	#define __restore_v_state(task, regs) (0)
	#endif

	static long restore_sigcontext(struct pt_regs *regs,
	struct sigcontext __user *sc)
	{
	void __user *sc_ext_ptr = &sc->sc_extdesc.hdr;
	__u32 rsvd;
	long err;
	/* sc_regs is structured the same as the start of pt_regs */
	err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
	if (unlikely(err))
	return err;

	/* Restore the floating-point state. */
	if (has_fpu()) {
	err = restore_fp_state(regs, &sc->sc_fpregs);
	if (unlikely(err))
	return err;
	}

	/* Check the reserved word before extensions parsing */
	err = __get_user(rsvd, &sc->sc_extdesc.reserved);
	if (unlikely(err))
	return err;
	if (unlikely(rsvd))
	return -EINVAL;

	while (!err) {
	__u32 magic, size;
	struct __riscv_ctx_hdr __user *head = sc_ext_ptr;

	err \|= __get_user(magic, &head->magic);
	err \|= __get_user(size, &head->size);
	if (unlikely(err))
	return err;

	sc_ext_ptr += sizeof(*head);
	switch (magic) {
	case END_MAGIC:
	if (size != END_HDR_SIZE)
	return -EINVAL;

	return 0;
	case RISCV_V_MAGIC:
	if (!has_vector() \|\| !riscv_v_vstate_query(regs) \|\|
	size != riscv_v_sc_size)
	return -EINVAL;

	err = __restore_v_state(regs, sc_ext_ptr);
	break;
	default:
	return -EINVAL;
	}
	sc_ext_ptr = (void __user *)head + size;
	}
	return err;
	}

	static size_t get_rt_frame_size(bool cal_all)
	{
	struct rt_sigframe __user *frame;
	size_t frame_size;
	size_t total_context_size = 0;

	frame_size = sizeof(*frame);

	if (has_vector()) {
	if (cal_all \|\| riscv_v_vstate_query(task_pt_regs(current)))
	total_context_size += riscv_v_sc_size;
	}
	/*
	* Preserved a __riscv_ctx_hdr for END signal context header if an
	* extension uses __riscv_extra_ext_header
	*/
	if (total_context_size)
	total_context_size += sizeof(struct __riscv_ctx_hdr);

	frame_size += total_context_size;

	frame_size = round_up(frame_size, 16);
	return frame_size;
	}

	SYSCALL_DEFINE0(rt_sigreturn)
	{
	struct pt_regs *regs = current_pt_regs();
	struct rt_sigframe __user *frame;
	struct task_struct *task;
	sigset_t set;
	size_t frame_size = get_rt_frame_size(false);

	/* Always make any pending restarted system calls return -EINTR */
	current->restart_block.fn = do_no_restart_syscall;

	frame = (struct rt_sigframe __user *)regs->sp;

	if (!access_ok(frame, frame_size))
	goto badframe;

	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
	goto badframe;

	set_current_blocked(&set);

	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
	goto badframe;

	if (restore_altstack(&frame->uc.uc_stack))
	goto badframe;

	regs->cause = -1UL;

	return regs->a0;

	badframe:
	task = current;
	if (show_unhandled_signals) {
	pr_info_ratelimited(
	"%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
	task->comm, task_pid_nr(task), __func__,
	frame, (void )regs->epc, (void )regs->sp);
	}
	force_sig(SIGSEGV);
	return 0;
	}

	static long setup_sigcontext(struct rt_sigframe __user *frame,
	struct pt_regs *regs)
	{
	struct sigcontext __user *sc = &frame->uc.uc_mcontext;
	struct __riscv_ctx_hdr __user *sc_ext_ptr = &sc->sc_extdesc.hdr;
	long err;

	/* sc_regs is structured the same as the start of pt_regs */
	err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
	/* Save the floating-point state. */
	if (has_fpu())
	err \|= save_fp_state(regs, &sc->sc_fpregs);
	/* Save the vector state. */
	if (has_vector() && riscv_v_vstate_query(regs))
	err \|= save_v_state(regs, (void __user **)&sc_ext_ptr);
	/* Write zero to fp-reserved space and check it on restore_sigcontext */
	err \|= __put_user(0, &sc->sc_extdesc.reserved);
	/* And put END __riscv_ctx_hdr at the end. */
	err \|= __put_user(END_MAGIC, &sc_ext_ptr->magic);
	err \|= __put_user(END_HDR_SIZE, &sc_ext_ptr->size);

	return err;
	}

	static inline void __user get_sigframe(struct ksignal ksig,
	struct pt_regs *regs, size_t framesize)
	{
	unsigned long sp;
	/* Default to using normal stack */
	sp = regs->sp;

	/*
	* If we are on the alternate signal stack and would overflow it, don't.
	* Return an always-bogus address instead so we will die with SIGSEGV.
	*/
	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
	return (void __user __force *)(-1UL);

	/* This is the X/Open sanctioned signal stack switching. */
	sp = sigsp(sp, ksig) - framesize;

	/* Align the stack frame. */
	sp &= ~0xfUL;

	return (void __user *)sp;
	}

	static int setup_rt_frame(struct ksignal ksig, sigset_t set,
	struct pt_regs *regs)
	{
	struct rt_sigframe __user *frame;
	long err = 0;
	unsigned long __maybe_unused addr;
	size_t frame_size = get_rt_frame_size(false);

	frame = get_sigframe(ksig, regs, frame_size);
	if (!access_ok(frame, frame_size))
	return -EFAULT;

	err \|= copy_siginfo_to_user(&frame->info, &ksig->info);

	/* Create the ucontext. */
	err \|= __put_user(0, &frame->uc.uc_flags);
	err \|= __put_user(NULL, &frame->uc.uc_link);
	err \|= __save_altstack(&frame->uc.uc_stack, regs->sp);
	err \|= setup_sigcontext(frame, regs);
	err \|= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
	if (err)
	return -EFAULT;

	/* Set up to return from userspace. */
	#ifdef CONFIG_MMU
	regs->ra = (unsigned long)VDSO_SYMBOL(
	current->mm->context.vdso, rt_sigreturn);
	#else
	/*
	* For the nommu case we don't have a VDSO. Instead we push two
	* instructions to call the rt_sigreturn syscall onto the user stack.
	*/
	if (copy_to_user(&frame->sigreturn_code, __user_rt_sigreturn,
	sizeof(frame->sigreturn_code)))
	return -EFAULT;

	addr = (unsigned long)&frame->sigreturn_code;
	/* Make sure the two instructions are pushed to icache. */
	flush_icache_range(addr, addr + sizeof(frame->sigreturn_code));

	regs->ra = addr;
	#endif /* CONFIG_MMU */

	/*
	* Set up registers for signal handler.
	* Registers that we don't modify keep the value they had from
	* user-space at the time we took the signal.
	* We always pass siginfo and mcontext, regardless of SA_SIGINFO,
	* since some things rely on this (e.g. glibc's debug/segfault.c).
	*/
	regs->epc = (unsigned long)ksig->ka.sa.sa_handler;
	regs->sp = (unsigned long)frame;
	regs->a0 = ksig->sig; /* a0: signal number */
	regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */
	regs->a2 = (unsigned long)(&frame->uc); /* a2: ucontext pointer */

	#if DEBUG_SIG
	pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n",
	current->comm, task_pid_nr(current), ksig->sig,
	(void )regs->epc, (void )regs->ra, frame);
	#endif

	return 0;
	}

	static void handle_signal(struct ksignal ksig, struct pt_regs regs)
	{
	sigset_t *oldset = sigmask_to_save();
	int ret;

	rseq_signal_deliver(ksig, regs);

	/* Set up the stack frame */
	if (is_compat_task())
	ret = compat_setup_rt_frame(ksig, oldset, regs);
	else
	ret = setup_rt_frame(ksig, oldset, regs);

	signal_setup_done(ret, ksig, 0);
	}

	void arch_do_signal_or_restart(struct pt_regs *regs)
	{
	unsigned long continue_addr = 0, restart_addr = 0;
	int retval = 0;
	struct ksignal ksig;
	bool syscall = (regs->cause == EXC_SYSCALL);

	/* If we were from a system call, check for system call restarting */
	if (syscall) {
	continue_addr = regs->epc;
	restart_addr = continue_addr - 4;
	retval = regs->a0;

	/* Avoid additional syscall restarting via ret_from_exception */
	regs->cause = -1UL;

	/*
	* 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->a0 = regs->orig_a0;
	regs->epc = 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->epc == restart_addr &&
	(retval == -ERESTARTNOHAND \|\|
	retval == -ERESTART_RESTARTBLOCK \|\|
	(retval == -ERESTARTSYS &&
	!(ksig.ka.sa.sa_flags & SA_RESTART)))) {
	regs->a0 = -EINTR;
	regs->epc = continue_addr;
	}

	/* Actually deliver the signal */
	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->epc == restart_addr && retval == -ERESTART_RESTARTBLOCK)
	regs->a7 = __NR_restart_syscall;

	/*
	* If there is no signal to deliver, we just put the saved
	* sigmask back.
	*/
	restore_saved_sigmask();
	}

	void init_rt_signal_env(void);
	void __init init_rt_signal_env(void)
	{
	riscv_v_sc_size = sizeof(struct __riscv_ctx_hdr) +
	sizeof(struct __sc_riscv_v_state) + riscv_v_vsize;
	/*
	* Determine the stack space required for guaranteed signal delivery.
	* The signal_minsigstksz will be populated into the AT_MINSIGSTKSZ entry
	* in the auxiliary array at process startup.
	*/
	signal_minsigstksz = get_rt_frame_size(true);
	}

	#ifdef CONFIG_DYNAMIC_SIGFRAME
	bool sigaltstack_size_valid(size_t ss_size)
	{
	return ss_size > get_rt_frame_size(false);
	}
	#endif /* CONFIG_DYNAMIC_SIGFRAME */