arch/metag/kernel/signal.c - arm/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  *  Copyright (C) 1991,1992  Linus Torvalds
  *  Copyright (C) 2005-2012  Imagination Technologies Ltd.
  *
  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  *
  */

 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/kernel.h>
 #include <linux/signal.h>
 #include <linux/errno.h>
 #include <linux/wait.h>
 #include <linux/ptrace.h>
 #include <linux/unistd.h>
 #include <linux/stddef.h>
 #include <linux/personality.h>
 #include <linux/uaccess.h>
 #include <linux/tracehook.h>

 #include <asm/ucontext.h>
 #include <asm/cacheflush.h>
 #include <asm/switch.h>
 #include <asm/syscall.h>
 #include <asm/syscalls.h>

 #define REG_FLAGS	ctx.SaveMask
 #define REG_RETVAL	ctx.DX[0].U0
 #define REG_SYSCALL	ctx.DX[0].U1
 #define REG_SP		ctx.AX[0].U0
 #define REG_ARG1	ctx.DX[3].U1
 #define REG_ARG2	ctx.DX[3].U0
 #define REG_ARG3	ctx.DX[2].U1
 #define REG_PC		ctx.CurrPC
 #define REG_RTP		ctx.DX[4].U1

 struct rt_sigframe {
 	struct siginfo info;
 	struct ucontext uc;
 	unsigned long retcode[2];
 };

 static int restore_sigcontext(struct pt_regs *regs,
 			      struct sigcontext __user *sc)
 {
 	int err;

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

 	err = metag_gp_regs_copyin(regs, 0, sizeof(struct user_gp_regs), NULL,
 				   &sc->regs);
 	if (!err)
 		err = metag_cb_regs_copyin(regs, 0,
 					   sizeof(struct user_cb_regs), NULL,
 					   &sc->cb);
 	if (!err)
 		err = metag_rp_state_copyin(regs, 0,
 					    sizeof(struct user_rp_state), NULL,
 					    &sc->rp);

 	/* This is a user-mode context. */
 	regs->REG_FLAGS |= TBICTX_PRIV_BIT;

 	return err;
 }

 long sys_rt_sigreturn(void)
 {
 	/* NOTE - Meta stack goes UPWARDS - so we wind the stack back */
 	struct pt_regs *regs = current_pt_regs();
 	struct rt_sigframe __user *frame;
 	sigset_t set;

 	frame = (__force struct rt_sigframe __user *)(regs->REG_SP -
 						      sizeof(*frame));

 	if (!access_ok(VERIFY_READ, 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->REG_RETVAL;

 badframe:
 	force_sig(SIGSEGV, current);

 	return 0;
 }

 static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 			    unsigned long mask)
 {
 	int err;

 	err = metag_gp_regs_copyout(regs, 0, sizeof(struct user_gp_regs), NULL,
 				    &sc->regs);

 	if (!err)
 		err = metag_cb_regs_copyout(regs, 0,
 					    sizeof(struct user_cb_regs), NULL,
 					    &sc->cb);
 	if (!err)
 		err = metag_rp_state_copyout(regs, 0,
 					     sizeof(struct user_rp_state), NULL,
 					     &sc->rp);

 	/* OK, clear that cbuf flag in the old context, or our stored
 	 * catch buffer will be restored when we go to call the signal
 	 * handler. Also clear out the CBRP RA/RD pipe bit incase
 	 * that is pending as well!
 	 * Note that as we have already stored this context, these
 	 * flags will get restored on sigreturn to their original
 	 * state.
 	 */
 	regs->REG_FLAGS &= ~(TBICTX_XCBF_BIT | TBICTX_CBUF_BIT |
 			     TBICTX_CBRP_BIT);

 	/* Clear out the LSM_STEP bits in case we are in the middle of
 	 * and MSET/MGET.
 	 */
 	regs->ctx.Flags &= ~TXSTATUS_LSM_STEP_BITS;

 	err |= __put_user(mask, &sc->oldmask);

 	return err;
 }

 /*
  * Determine which stack to use..
  */
 static void __user *get_sigframe(struct ksignal *ksig, unsigned long sp)
 {
 	sp = sigsp(sp, ksig);
 	sp = (sp + 7) & ~7;			/* 8byte align stack */

 	return (void __user *)sp;
 }

 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 			  struct pt_regs *regs)
 {
 	struct rt_sigframe __user *frame;
 	int err;
 	unsigned long code;

 	frame = get_sigframe(ksig, regs->REG_SP);
 	if (!access_ok(VERIFY_WRITE, 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(0, (unsigned long __user *)&frame->uc.uc_link);
 	err |= __save_altstack(&frame->uc.uc_stack, regs->REG_SP);
 	err |= setup_sigcontext(&frame->uc.uc_mcontext,
 				regs, set->sig[0]);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

 	if (err)
 		return -EFAULT;

 	/* Set up to return from userspace.  */

 	/* MOV D1Re0 (D1.0), #__NR_rt_sigreturn */
 	code = 0x03000004 | (__NR_rt_sigreturn << 3);
 	err |= __put_user(code, (unsigned long __user *)(&frame->retcode[0]));

 	/* SWITCH #__METAG_SW_SYS */
 	code = __METAG_SW_ENCODING(SYS);
 	err |= __put_user(code, (unsigned long __user *)(&frame->retcode[1]));

 	if (err)
 		return -EFAULT;

 	/* Set up registers for signal handler */
 	regs->REG_RTP = (unsigned long) frame->retcode;
 	regs->REG_SP = (unsigned long) frame + sizeof(*frame);
 	regs->REG_ARG1 = ksig->sig;
 	regs->REG_ARG2 = (unsigned long) &frame->info;
 	regs->REG_ARG3 = (unsigned long) &frame->uc;
 	regs->REG_PC = (unsigned long) ksig->ka.sa.sa_handler;

 	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08x pr=%08x\n",
 		 current->comm, current->pid, frame, regs->REG_PC,
 		 regs->REG_RTP);

 	/* Now pass size of 'new code' into sigtramp so we can do a more
 	 * effective cache flush - directed rather than 'full flush'.
 	 */
 	flush_cache_sigtramp(regs->REG_RTP, sizeof(frame->retcode));

 	return 0;
 }

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

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

 	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 }

  /*
   * Notes for Meta.
   * We have moved from the old 2.4.9 SH way of using syscall_nr (in the stored
   * context) to passing in the syscall flag on the stack.
   * This is because having syscall_nr in our context does not fit with TBX, and
   * corrupted the stack.
   */
 static int do_signal(struct pt_regs *regs, int syscall)
 {
 	unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
 	int restart = 0;
 	struct ksignal ksig;

 	/*
 	 * By the end of rt_sigreturn the context describes the point that the
 	 * signal was taken (which may happen to be just before a syscall if
 	 * it's already been restarted). This should *never* be mistaken for a
 	 * system call in need of restarting.
 	 */
 	if (syscall == __NR_rt_sigreturn)
 		syscall = -1;

 	/* Did we come from a system call? */
 	if (syscall >= 0) {
 		continue_addr = regs->REG_PC;
 		restart_addr = continue_addr - 4;
 		retval = regs->REG_RETVAL;

 		/*
 		 * Prepare for system call restart. We do this here so that a
 		 * debugger will see the already changed PC.
 		 */
 		switch (retval) {
 		case -ERESTART_RESTARTBLOCK:
 			restart = -2;
 		case -ERESTARTNOHAND:
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
 			++restart;
 			regs->REG_PC = restart_addr;
 			break;
 		}
 	}

 	/*
 	 * Get the signal to deliver. When running under ptrace, at this point
 	 * the debugger may change all our registers ...
 	 */
 	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->REG_PC != restart_addr)
 		restart = 0;
 	if (ksig.sig > 0) {
 		if (unlikely(restart)) {
 			if (retval == -ERESTARTNOHAND
 			    || retval == -ERESTART_RESTARTBLOCK
 			    || (retval == -ERESTARTSYS
 				&& !(ksig.ka.sa.sa_flags & SA_RESTART))) {
 				regs->REG_RETVAL = -EINTR;
 				regs->REG_PC = continue_addr;
 			}
 		}

 		/* Whee! Actually deliver the signal.  */
 		handle_signal(&ksig, regs);
 		return 0;
 	}

 	/* Handlerless -ERESTART_RESTARTBLOCK re-enters via restart_syscall */
 	if (unlikely(restart < 0))
 		regs->REG_SYSCALL = __NR_restart_syscall;

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

 	return restart;
 }

 int do_work_pending(struct pt_regs *regs, unsigned int thread_flags,
 		    int syscall)
 {
 	do {
 		if (likely(thread_flags & _TIF_NEED_RESCHED)) {
 			schedule();
 		} else {
 			if (unlikely(!user_mode(regs)))
 				return 0;
 			local_irq_enable();
 			if (thread_flags & _TIF_SIGPENDING) {
 				int restart = do_signal(regs, syscall);
 				if (unlikely(restart)) {
 					/*
 					 * Restart without handlers.
 					 * Deal with it without leaving
 					 * the kernel space.
 					 */
 					return restart;
 				}
 				syscall = -1;
 			} else {
 				clear_thread_flag(TIF_NOTIFY_RESUME);
 				tracehook_notify_resume(regs);
 			}
 		}
 		local_irq_disable();
 		thread_flags = current_thread_info()->flags;
 	} while (thread_flags & _TIF_WORK_MASK);
 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (C) 1991,1992 Linus Torvalds
	* Copyright (C) 2005-2012 Imagination Technologies Ltd.
	*
	* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
	*
	*/

	#include <linux/sched.h>
	#include <linux/sched/task_stack.h>
	#include <linux/mm.h>
	#include <linux/smp.h>
	#include <linux/kernel.h>
	#include <linux/signal.h>
	#include <linux/errno.h>
	#include <linux/wait.h>
	#include <linux/ptrace.h>
	#include <linux/unistd.h>
	#include <linux/stddef.h>
	#include <linux/personality.h>
	#include <linux/uaccess.h>
	#include <linux/tracehook.h>

	#include <asm/ucontext.h>
	#include <asm/cacheflush.h>
	#include <asm/switch.h>
	#include <asm/syscall.h>
	#include <asm/syscalls.h>

	#define REG_FLAGS ctx.SaveMask
	#define REG_RETVAL ctx.DX[0].U0
	#define REG_SYSCALL ctx.DX[0].U1
	#define REG_SP ctx.AX[0].U0
	#define REG_ARG1 ctx.DX[3].U1
	#define REG_ARG2 ctx.DX[3].U0
	#define REG_ARG3 ctx.DX[2].U1
	#define REG_PC ctx.CurrPC
	#define REG_RTP ctx.DX[4].U1

	struct rt_sigframe {
	struct siginfo info;
	struct ucontext uc;
	unsigned long retcode[2];
	};

	static int restore_sigcontext(struct pt_regs *regs,
	struct sigcontext __user *sc)
	{
	int err;

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

	err = metag_gp_regs_copyin(regs, 0, sizeof(struct user_gp_regs), NULL,
	&sc->regs);
	if (!err)
	err = metag_cb_regs_copyin(regs, 0,
	sizeof(struct user_cb_regs), NULL,
	&sc->cb);
	if (!err)
	err = metag_rp_state_copyin(regs, 0,
	sizeof(struct user_rp_state), NULL,
	&sc->rp);

	/* This is a user-mode context. */
	regs->REG_FLAGS \|= TBICTX_PRIV_BIT;

	return err;
	}

	long sys_rt_sigreturn(void)
	{
	/* NOTE - Meta stack goes UPWARDS - so we wind the stack back */
	struct pt_regs *regs = current_pt_regs();
	struct rt_sigframe __user *frame;
	sigset_t set;

	frame = (__force struct rt_sigframe __user *)(regs->REG_SP -
	sizeof(*frame));

	if (!access_ok(VERIFY_READ, 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->REG_RETVAL;

	badframe:
	force_sig(SIGSEGV, current);

	return 0;
	}

	static int setup_sigcontext(struct sigcontext __user sc, struct pt_regs regs,
	unsigned long mask)
	{
	int err;

	err = metag_gp_regs_copyout(regs, 0, sizeof(struct user_gp_regs), NULL,
	&sc->regs);

	if (!err)
	err = metag_cb_regs_copyout(regs, 0,
	sizeof(struct user_cb_regs), NULL,
	&sc->cb);
	if (!err)
	err = metag_rp_state_copyout(regs, 0,
	sizeof(struct user_rp_state), NULL,
	&sc->rp);

	/* OK, clear that cbuf flag in the old context, or our stored
	* catch buffer will be restored when we go to call the signal
	* handler. Also clear out the CBRP RA/RD pipe bit incase
	* that is pending as well!
	* Note that as we have already stored this context, these
	* flags will get restored on sigreturn to their original
	* state.
	*/
	regs->REG_FLAGS &= ~(TBICTX_XCBF_BIT \| TBICTX_CBUF_BIT \|
	TBICTX_CBRP_BIT);

	/* Clear out the LSM_STEP bits in case we are in the middle of
	* and MSET/MGET.
	*/
	regs->ctx.Flags &= ~TXSTATUS_LSM_STEP_BITS;

	err \|= __put_user(mask, &sc->oldmask);

	return err;
	}

	/*
	* Determine which stack to use..
	*/
	static void __user get_sigframe(struct ksignal ksig, unsigned long sp)
	{
	sp = sigsp(sp, ksig);
	sp = (sp + 7) & ~7; /* 8byte align stack */

	return (void __user *)sp;
	}

	static int setup_rt_frame(struct ksignal ksig, sigset_t set,
	struct pt_regs *regs)
	{
	struct rt_sigframe __user *frame;
	int err;
	unsigned long code;

	frame = get_sigframe(ksig, regs->REG_SP);
	if (!access_ok(VERIFY_WRITE, 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(0, (unsigned long __user *)&frame->uc.uc_link);
	err \|= __save_altstack(&frame->uc.uc_stack, regs->REG_SP);
	err \|= setup_sigcontext(&frame->uc.uc_mcontext,
	regs, set->sig[0]);
	err \|= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	if (err)
	return -EFAULT;

	/* Set up to return from userspace. */

	/* MOV D1Re0 (D1.0), #__NR_rt_sigreturn */
	code = 0x03000004 \| (__NR_rt_sigreturn << 3);
	err \|= __put_user(code, (unsigned long __user *)(&frame->retcode[0]));

	/* SWITCH #__METAG_SW_SYS */
	code = __METAG_SW_ENCODING(SYS);
	err \|= __put_user(code, (unsigned long __user *)(&frame->retcode[1]));

	if (err)
	return -EFAULT;

	/* Set up registers for signal handler */
	regs->REG_RTP = (unsigned long) frame->retcode;
	regs->REG_SP = (unsigned long) frame + sizeof(*frame);
	regs->REG_ARG1 = ksig->sig;
	regs->REG_ARG2 = (unsigned long) &frame->info;
	regs->REG_ARG3 = (unsigned long) &frame->uc;
	regs->REG_PC = (unsigned long) ksig->ka.sa.sa_handler;

	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08x pr=%08x\n",
	current->comm, current->pid, frame, regs->REG_PC,
	regs->REG_RTP);

	/* Now pass size of 'new code' into sigtramp so we can do a more
	* effective cache flush - directed rather than 'full flush'.
	*/
	flush_cache_sigtramp(regs->REG_RTP, sizeof(frame->retcode));

	return 0;
	}

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

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

	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
	}

	/*
	* Notes for Meta.
	* We have moved from the old 2.4.9 SH way of using syscall_nr (in the stored
	* context) to passing in the syscall flag on the stack.
	* This is because having syscall_nr in our context does not fit with TBX, and
	* corrupted the stack.
	*/
	static int do_signal(struct pt_regs *regs, int syscall)
	{
	unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
	int restart = 0;
	struct ksignal ksig;

	/*
	* By the end of rt_sigreturn the context describes the point that the
	* signal was taken (which may happen to be just before a syscall if
	* it's already been restarted). This should never be mistaken for a
	* system call in need of restarting.
	*/
	if (syscall == __NR_rt_sigreturn)
	syscall = -1;

	/* Did we come from a system call? */
	if (syscall >= 0) {
	continue_addr = regs->REG_PC;
	restart_addr = continue_addr - 4;
	retval = regs->REG_RETVAL;

	/*
	* Prepare for system call restart. We do this here so that a
	* debugger will see the already changed PC.
	*/
	switch (retval) {
	case -ERESTART_RESTARTBLOCK:
	restart = -2;
	case -ERESTARTNOHAND:
	case -ERESTARTSYS:
	case -ERESTARTNOINTR:
	++restart;
	regs->REG_PC = restart_addr;
	break;
	}
	}

	/*
	* Get the signal to deliver. When running under ptrace, at this point
	* the debugger may change all our registers ...
	*/
	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->REG_PC != restart_addr)
	restart = 0;
	if (ksig.sig > 0) {
	if (unlikely(restart)) {
	if (retval == -ERESTARTNOHAND
	\|\| retval == -ERESTART_RESTARTBLOCK
	\|\| (retval == -ERESTARTSYS
	&& !(ksig.ka.sa.sa_flags & SA_RESTART))) {
	regs->REG_RETVAL = -EINTR;
	regs->REG_PC = continue_addr;
	}
	}

	/* Whee! Actually deliver the signal. */
	handle_signal(&ksig, regs);
	return 0;
	}

	/* Handlerless -ERESTART_RESTARTBLOCK re-enters via restart_syscall */
	if (unlikely(restart < 0))
	regs->REG_SYSCALL = __NR_restart_syscall;

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

	return restart;
	}

	int do_work_pending(struct pt_regs *regs, unsigned int thread_flags,
	int syscall)
	{
	do {
	if (likely(thread_flags & _TIF_NEED_RESCHED)) {
	schedule();
	} else {
	if (unlikely(!user_mode(regs)))
	return 0;
	local_irq_enable();
	if (thread_flags & _TIF_SIGPENDING) {
	int restart = do_signal(regs, syscall);
	if (unlikely(restart)) {
	/*
	* Restart without handlers.
	* Deal with it without leaving
	* the kernel space.
	*/
	return restart;
	}
	syscall = -1;
	} else {
	clear_thread_flag(TIF_NOTIFY_RESUME);
	tracehook_notify_resume(regs);
	}
	}
	local_irq_disable();
	thread_flags = current_thread_info()->flags;
	} while (thread_flags & _TIF_WORK_MASK);
	return 0;
	}