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/signal.h>
 #include <linux/uaccess.h>
 #include <linux/syscalls.h>
 #include <linux/resume_user_mode.h>
 #include <linux/linkage.h>

 #include <asm/ucontext.h>
 #include <asm/vdso.h>
 #include <asm/switch_to.h>
 #include <asm/csr.h>

 extern u32 __user_rt_sigreturn[2];

 #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;
 	size_t i;

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

 	fstate_restore(current, regs);

 	/* We support no other extension state at this time. */
 	for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
 		u32 value;

 		err = __get_user(value, &sc_fpregs->q.reserved[i]);
 		if (unlikely(err))
 			break;
 		if (value != 0)
 			return -EINVAL;
 	}

 	return err;
 }

 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;
 	size_t i;

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

 	/* We support no other extension state at this time. */
 	for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
 		err = __put_user(0, &sc_fpregs->q.reserved[i]);
 		if (unlikely(err))
 			break;
 	}

 	return err;
 }
 #else
 #define save_fp_state(task, regs) (0)
 #define restore_fp_state(task, regs) (0)
 #endif

 static long restore_sigcontext(struct pt_regs *regs,
 	struct sigcontext __user *sc)
 {
 	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));
 	/* Restore the floating-point state. */
 	if (has_fpu())
 		err |= restore_fp_state(regs, &sc->sc_fpregs);
 	return err;
 }

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

 	/* 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, sizeof(*frame)))
 		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;

 	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;
 	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);
 	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;

 	frame = get_sigframe(ksig, regs, sizeof(*frame));
 	if (!access_ok(frame, sizeof(*frame)))
 		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;
 	regs->ra = (unsigned long)&frame->sigreturn_code;
 #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;

 	/* Are we from a system call? */
 	if (regs->cause == EXC_SYSCALL) {
 		/* Avoid additional syscall restarting via ret_from_exception */
 		regs->cause = -1UL;
 		/* If so, check system call restarting.. */
 		switch (regs->a0) {
 		case -ERESTART_RESTARTBLOCK:
 		case -ERESTARTNOHAND:
 			regs->a0 = -EINTR;
 			break;

 		case -ERESTARTSYS:
 			if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 				regs->a0 = -EINTR;
 				break;
 			}
 			fallthrough;
 		case -ERESTARTNOINTR:
                         regs->a0 = regs->orig_a0;
 			regs->epc -= 0x4;
 			break;
 		}
 	}

 	rseq_signal_deliver(ksig, regs);

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

 	signal_setup_done(ret, ksig, 0);
 }

 static void do_signal(struct pt_regs *regs)
 {
 	struct ksignal ksig;

 	if (get_signal(&ksig)) {
 		/* Actually deliver the signal */
 		handle_signal(&ksig, regs);
 		return;
 	}

 	/* Did we come from a system call? */
 	if (regs->cause == EXC_SYSCALL) {
 		/* Avoid additional syscall restarting via ret_from_exception */
 		regs->cause = -1UL;

 		/* Restart the system call - no handlers present */
 		switch (regs->a0) {
 		case -ERESTARTNOHAND:
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
                         regs->a0 = regs->orig_a0;
 			regs->epc -= 0x4;
 			break;
 		case -ERESTART_RESTARTBLOCK:
                         regs->a0 = regs->orig_a0;
 			regs->a7 = __NR_restart_syscall;
 			regs->epc -= 0x4;
 			break;
 		}
 	}

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

 /*
  * notification of userspace execution resumption
  * - triggered by the _TIF_WORK_MASK flags
  */
 asmlinkage __visible void do_notify_resume(struct pt_regs *regs,
 					   unsigned long thread_info_flags)
 {
 	if (thread_info_flags & _TIF_UPROBE)
 		uprobe_notify_resume(regs);

 	/* Handle pending signal delivery */
 	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs);

 	if (thread_info_flags & _TIF_NOTIFY_RESUME)
 		resume_user_mode_work(regs);
 }
	// 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/signal.h>
	#include <linux/uaccess.h>
	#include <linux/syscalls.h>
	#include <linux/resume_user_mode.h>
	#include <linux/linkage.h>

	#include <asm/ucontext.h>
	#include <asm/vdso.h>
	#include <asm/switch_to.h>
	#include <asm/csr.h>

	extern u32 __user_rt_sigreturn[2];

	#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;
	size_t i;

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

	fstate_restore(current, regs);

	/* We support no other extension state at this time. */
	for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
	u32 value;

	err = __get_user(value, &sc_fpregs->q.reserved[i]);
	if (unlikely(err))
	break;
	if (value != 0)
	return -EINVAL;
	}

	return err;
	}

	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;
	size_t i;

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

	/* We support no other extension state at this time. */
	for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
	err = __put_user(0, &sc_fpregs->q.reserved[i]);
	if (unlikely(err))
	break;
	}

	return err;
	}
	#else
	#define save_fp_state(task, regs) (0)
	#define restore_fp_state(task, regs) (0)
	#endif

	static long restore_sigcontext(struct pt_regs *regs,
	struct sigcontext __user *sc)
	{
	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));
	/* Restore the floating-point state. */
	if (has_fpu())
	err \|= restore_fp_state(regs, &sc->sc_fpregs);
	return err;
	}

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

	/* 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, sizeof(*frame)))
	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;

	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;
	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);
	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;

	frame = get_sigframe(ksig, regs, sizeof(*frame));
	if (!access_ok(frame, sizeof(*frame)))
	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;
	regs->ra = (unsigned long)&frame->sigreturn_code;
	#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;

	/* Are we from a system call? */
	if (regs->cause == EXC_SYSCALL) {
	/* Avoid additional syscall restarting via ret_from_exception */
	regs->cause = -1UL;
	/* If so, check system call restarting.. */
	switch (regs->a0) {
	case -ERESTART_RESTARTBLOCK:
	case -ERESTARTNOHAND:
	regs->a0 = -EINTR;
	break;

	case -ERESTARTSYS:
	if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
	regs->a0 = -EINTR;
	break;
	}
	fallthrough;
	case -ERESTARTNOINTR:
	regs->a0 = regs->orig_a0;
	regs->epc -= 0x4;
	break;
	}
	}

	rseq_signal_deliver(ksig, regs);

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

	signal_setup_done(ret, ksig, 0);
	}

	static void do_signal(struct pt_regs *regs)
	{
	struct ksignal ksig;

	if (get_signal(&ksig)) {
	/* Actually deliver the signal */
	handle_signal(&ksig, regs);
	return;
	}

	/* Did we come from a system call? */
	if (regs->cause == EXC_SYSCALL) {
	/* Avoid additional syscall restarting via ret_from_exception */
	regs->cause = -1UL;

	/* Restart the system call - no handlers present */
	switch (regs->a0) {
	case -ERESTARTNOHAND:
	case -ERESTARTSYS:
	case -ERESTARTNOINTR:
	regs->a0 = regs->orig_a0;
	regs->epc -= 0x4;
	break;
	case -ERESTART_RESTARTBLOCK:
	regs->a0 = regs->orig_a0;
	regs->a7 = __NR_restart_syscall;
	regs->epc -= 0x4;
	break;
	}
	}

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

	/*
	* notification of userspace execution resumption
	* - triggered by the _TIF_WORK_MASK flags
	*/
	asmlinkage __visible void do_notify_resume(struct pt_regs *regs,
	unsigned long thread_info_flags)
	{
	if (thread_info_flags & _TIF_UPROBE)
	uprobe_notify_resume(regs);

	/* Handle pending signal delivery */
	if (thread_info_flags & (_TIF_SIGPENDING \| _TIF_NOTIFY_SIGNAL))
	do_signal(regs);

	if (thread_info_flags & _TIF_NOTIFY_RESUME)
	resume_user_mode_work(regs);
	}