text: /* MN10300 Signal handling
   *
   * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public Licence
   * as published by the Free Software Foundation; either version
   * 2 of the Licence, or (at your option) any later version.
   */
  
  #include <linux/sched.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/tty.h>
  #include <linux/personality.h>
  #include <linux/suspend.h>
  #include <linux/tracehook.h>
  #include <asm/cacheflush.h>
  #include <asm/ucontext.h>
  #include <asm/uaccess.h>
  #include <asm/fpu.h>
  #include "sigframe.h"
  
  #define DEBUG_SIG 0
  
  /*
   * do a signal return; undo the signal stack.
   */
  static int restore_sigcontext(struct pt_regs *regs,
  			      struct sigcontext __user *sc, long *_d0)
  {
  	unsigned int err = 0;
  
  	/* Always make any pending restarted system calls return -EINTR */
  	current->restart_block.fn = do_no_restart_syscall;
  
  	if (is_using_fpu(current))
  		fpu_kill_state(current);
  
  #define COPY(x) err |= __get_user(regs->x, &sc->x)
  	COPY(d1); COPY(d2); COPY(d3);
  	COPY(a0); COPY(a1); COPY(a2); COPY(a3);
  	COPY(e0); COPY(e1); COPY(e2); COPY(e3);
  	COPY(e4); COPY(e5); COPY(e6); COPY(e7);
  	COPY(lar); COPY(lir);
  	COPY(mdr); COPY(mdrq);
  	COPY(mcvf); COPY(mcrl); COPY(mcrh);
  	COPY(sp); COPY(pc);
  #undef COPY
  
  	{
  		unsigned int tmpflags;
  #ifndef CONFIG_MN10300_USING_JTAG
  #define USER_EPSW (EPSW_FLAG_Z | EPSW_FLAG_N | EPSW_FLAG_C | EPSW_FLAG_V | \
  		   EPSW_T | EPSW_nAR)
  #else
  #define USER_EPSW (EPSW_FLAG_Z | EPSW_FLAG_N | EPSW_FLAG_C | EPSW_FLAG_V | \
  		   EPSW_nAR)
  #endif
  		err |= __get_user(tmpflags, &sc->epsw);
  		regs->epsw = (regs->epsw & ~USER_EPSW) |
  		  (tmpflags & USER_EPSW);
  		regs->orig_d0 = -1;		/* disable syscall checks */
  	}
  
  	{
  		struct fpucontext *buf;
  		err |= __get_user(buf, &sc->fpucontext);
  		if (buf) {
  			if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
  				goto badframe;
  			err |= fpu_restore_sigcontext(buf);
  		}
  	}
  
  	err |= __get_user(*_d0, &sc->d0);
  	return err;
  
  badframe:
  	return 1;
  }
  
  /*
   * standard signal return syscall
   */
  asmlinkage long sys_sigreturn(void)
  {
  	struct sigframe __user *frame;
  	sigset_t set;
  	long d0;
  
  	frame = (struct sigframe __user *) current_frame()->sp;
  	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  		goto badframe;
  	if (__get_user(set.sig[0], &frame->sc.oldmask))
  		goto badframe;
  
  	if (_NSIG_WORDS > 1 &&
  	    __copy_from_user(&set.sig[1], &frame->extramask,
  			     sizeof(frame->extramask)))
  		goto badframe;
  
  	set_current_blocked(&set);
  
  	if (restore_sigcontext(current_frame(), &frame->sc, &d0))
  		goto badframe;
  
  	return d0;
  
  badframe:
  	force_sig(SIGSEGV, current);
  	return 0;
  }
  
  /*
   * realtime signal return syscall
   */
  asmlinkage long sys_rt_sigreturn(void)
  {
  	struct rt_sigframe __user *frame;
  	sigset_t set;
  	long d0;
  
  	frame = (struct rt_sigframe __user *) current_frame()->sp;
  	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(current_frame(), &frame->uc.uc_mcontext, &d0))
  		goto badframe;
  
  	if (restore_altstack(&frame->uc.uc_stack))
  		goto badframe;
  
  	return d0;
  
  badframe:
  	force_sig(SIGSEGV, current);
  	return 0;
  }
  
  /*
   * store the userspace context into a signal frame
   */
  static int setup_sigcontext(struct sigcontext __user *sc,
  			    struct fpucontext *fpuctx,
  			    struct pt_regs *regs,
  			    unsigned long mask)
  {
  	int tmp, err = 0;
  
  #define COPY(x) err |= __put_user(regs->x, &sc->x)
  	COPY(d0); COPY(d1); COPY(d2); COPY(d3);
  	COPY(a0); COPY(a1); COPY(a2); COPY(a3);
  	COPY(e0); COPY(e1); COPY(e2); COPY(e3);
  	COPY(e4); COPY(e5); COPY(e6); COPY(e7);
  	COPY(lar); COPY(lir);
  	COPY(mdr); COPY(mdrq);
  	COPY(mcvf); COPY(mcrl); COPY(mcrh);
  	COPY(sp); COPY(epsw); COPY(pc);
  #undef COPY
  
  	tmp = fpu_setup_sigcontext(fpuctx);
  	if (tmp < 0)
  		err = 1;
  	else
  		err |= __put_user(tmp ? fpuctx : NULL, &sc->fpucontext);
  
  	/* non-iBCS2 extensions.. */
  	err |= __put_user(mask, &sc->oldmask);
  
  	return err;
  }
  
  /*
   * determine which stack to use..
   */
  static inline void __user *get_sigframe(struct ksignal *ksig,
  					struct pt_regs *regs,
  					size_t frame_size)
  {
  	unsigned long sp = sigsp(regs->sp, ksig);
  
  	return (void __user *) ((sp - frame_size) & ~7UL);
  }
  
  /*
   * set up a normal signal frame
   */
  static int setup_frame(struct ksignal *ksig, sigset_t *set,
  		       struct pt_regs *regs)
  {
  	struct sigframe __user *frame;
  	int sig = ksig->sig;
  
  	frame = get_sigframe(ksig, regs, sizeof(*frame));
  
  	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
  		return -EFAULT;
  
  	if (__put_user(sig, &frame->sig) < 0 ||
  	    __put_user(&frame->sc, &frame->psc) < 0)
  		return -EFAULT;
  
  	if (setup_sigcontext(&frame->sc, &frame->fpuctx, regs, set->sig[0]))
  		return -EFAULT;
  
  	if (_NSIG_WORDS > 1) {
  		if (__copy_to_user(frame->extramask, &set->sig[1],
  				   sizeof(frame->extramask)))
  			return -EFAULT;
  	}
  
  	/* set up to return from userspace.  If provided, use a stub already in
  	 * userspace */
  	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
  		if (__put_user(ksig->ka.sa.sa_restorer, &frame->pretcode))
  			return -EFAULT;
  	} else {
  		if (__put_user((void (*)(void))frame->retcode,
  			       &frame->pretcode))
  			return -EFAULT;
  		/* this is mov $,d0; syscall 0 */
  		if (__put_user(0x2c, (char *)(frame->retcode + 0)) ||
  		    __put_user(__NR_sigreturn, (char *)(frame->retcode + 1)) ||
  		    __put_user(0x00, (char *)(frame->retcode + 2)) ||
  		    __put_user(0xf0, (char *)(frame->retcode + 3)) ||
  		    __put_user(0xe0, (char *)(frame->retcode + 4)))
  			return -EFAULT;
  		flush_icache_range((unsigned long) frame->retcode,
  				   (unsigned long) frame->retcode + 5);
  	}
  
  	/* set up registers for signal handler */
  	regs->sp = (unsigned long) frame;
  	regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
  	regs->d0 = sig;
  	regs->d1 = (unsigned long) &frame->sc;
  
  #if DEBUG_SIG
  	printk(KERN_DEBUG "SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
  	       sig, current->comm, current->pid, frame, regs->pc,
  	       frame->pretcode);
  #endif
  
  	return 0;
  }
  
  /*
   * set up a realtime signal frame
   */
  static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
  			  struct pt_regs *regs)
  {
  	struct rt_sigframe __user *frame;
  	int sig = ksig->sig;
  
  	frame = get_sigframe(ksig, regs, sizeof(*frame));
  
  	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
  		return -EFAULT;
  
  	if (__put_user(sig, &frame->sig) ||
  	    __put_user(&frame->info, &frame->pinfo) ||
  	    __put_user(&frame->uc, &frame->puc) ||
  	    copy_siginfo_to_user(&frame->info, &ksig->info))
  		return -EFAULT;
  
  	/* create the ucontext.  */
  	if (__put_user(0, &frame->uc.uc_flags) ||
  	    __put_user(0, &frame->uc.uc_link) ||
  	    __save_altstack(&frame->uc.uc_stack, regs->sp) ||
  	    setup_sigcontext(&frame->uc.uc_mcontext,
  			     &frame->fpuctx, regs, set->sig[0]) ||
  	    __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)))
  		return -EFAULT;
  
  	/* set up to return from userspace.  If provided, use a stub already in
  	 * userspace */
  	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
  		if (__put_user(ksig->ka.sa.sa_restorer, &frame->pretcode))
  			return -EFAULT;
  
  	} else {
  		if (__put_user((void(*)(void))frame->retcode,
  			       &frame->pretcode) ||
  		    /* This is mov $,d0; syscall 0 */
  		    __put_user(0x2c, (char *)(frame->retcode + 0)) ||
  		    __put_user(__NR_rt_sigreturn,
  			       (char *)(frame->retcode + 1)) ||
  		    __put_user(0x00, (char *)(frame->retcode + 2)) ||
  		    __put_user(0xf0, (char *)(frame->retcode + 3)) ||
  		    __put_user(0xe0, (char *)(frame->retcode + 4)))
  			return -EFAULT;
  
  		flush_icache_range((u_long) frame->retcode,
  				   (u_long) frame->retcode + 5);
  	}
  
  	/* Set up registers for signal handler */
  	regs->sp = (unsigned long) frame;
  	regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
  	regs->d0 = sig;
  	regs->d1 = (long) &frame->info;
  
  #if DEBUG_SIG
  	printk(KERN_DEBUG "SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
  	       sig, current->comm, current->pid, frame, regs->pc,
  	       frame->pretcode);
  #endif
  
  	return 0;
  }
  
  static inline void stepback(struct pt_regs *regs)
  {
  	regs->pc -= 2;
  	regs->orig_d0 = -1;
  }
  
  /*
   * handle the actual delivery of a signal to userspace
   */
  static int 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->orig_d0 >= 0) {
  		/* If so, check system call restarting.. */
  		switch (regs->d0) {
  		case -ERESTART_RESTARTBLOCK:
  		case -ERESTARTNOHAND:
  			regs->d0 = -EINTR;
  			break;
  
  		case -ERESTARTSYS:
  			if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
  				regs->d0 = -EINTR;
  				break;
  			}
  
  			/* fallthrough */
  		case -ERESTARTNOINTR:
  			regs->d0 = regs->orig_d0;
  			stepback(regs);
  		}
  	}
  
  	/* Set up the stack frame */
  	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
  		ret = setup_rt_frame(ksig, oldset, regs);
  	else
  		ret = setup_frame(ksig, oldset, regs);
  
  	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
  	return 0;
  }
  
  /*
   * handle a potential signal
   */
  static void do_signal(struct pt_regs *regs)
  {
  	struct ksignal ksig;
  
  	if (get_signal(&ksig)) {
  		handle_signal(&ksig, regs);
  		return;
  	}
  
  	/* did we come from a system call? */
  	if (regs->orig_d0 >= 0) {
  		/* restart the system call - no handlers present */
  		switch (regs->d0) {
  		case -ERESTARTNOHAND:
  		case -ERESTARTSYS:
  		case -ERESTARTNOINTR:
  			regs->d0 = regs->orig_d0;
  			stepback(regs);
  			break;
  
  		case -ERESTART_RESTARTBLOCK:
  			regs->d0 = __NR_restart_syscall;
  			stepback(regs);
  			break;
  		}
  	}
  
  	/* if there's no signal to deliver, we just put the saved sigmask
  	 * back */
  	restore_saved_sigmask();
  }
  
  /*
   * notification of userspace execution resumption
   * - triggered by current->work.notify_resume
   */
  asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags)
  {
  	/* Pending single-step? */
  	if (thread_info_flags & _TIF_SINGLESTEP) {
  #ifndef CONFIG_MN10300_USING_JTAG
  		regs->epsw |= EPSW_T;
  		clear_thread_flag(TIF_SINGLESTEP);
  #else
  		BUG(); /* no h/w single-step if using JTAG unit */
  #endif
  	}
  
  	/* deal with pending signal delivery */
  	if (thread_info_flags & _TIF_SIGPENDING)
  		do_signal(regs);
  
  	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
  		clear_thread_flag(TIF_NOTIFY_RESUME);
  		tracehook_notify_resume(current_frame());
  	}
  }
  