signal.c

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	err |= __put_user(regs->hi, &sc->sc_mdhi);
	err |= __put_user(regs->lo, &sc->sc_mdlo);
	err |= __put_user(regs->cp0_cause, &sc->sc_cause);
	err |= __put_user(regs->cp0_badvaddr, &sc->sc_badvaddr);

	owned_fp = (current == last_task_used_math);
	err |= __put_user(owned_fp, &sc->sc_ownedfp);

	if (current->used_math) {	/* fp is active.  */
		set_cp0_status(ST0_CU1, ST0_CU1);
		err |= save_fp_context(sc);
		last_task_used_math = NULL;
		regs->cp0_status &= ~ST0_CU1;
		current->used_math = 0;
	}

	return err;
}

/*
 * Determine which stack to use..
 */
static inline void *
get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
{
	unsigned long sp;

	/* Default to using normal stack */
	sp = regs->regs[29];

	/* This is the X/Open sanctioned signal stack switching.  */
	if ((ka->sa.sa_flags & SA_ONSTACK) && ! on_sig_stack(sp))
                sp = current->sas_ss_sp + current->sas_ss_size;

	return (void *)((sp - frame_size) & ALMASK);
}

static void inline
setup_frame(struct k_sigaction * ka, struct pt_regs *regs,
            int signr, sigset_t *set)
{
	struct sigframe *frame;
	int err = 0;

	frame = get_sigframe(ka, regs, sizeof(*frame));
	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
		goto give_sigsegv;

	/* Set up to return from userspace.  If provided, use a stub already
	   in userspace.  */
	if (ka->sa.sa_flags & SA_RESTORER)
		regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
	else {
		/*
		 * Set up the return code ...
		 *
		 *         li      v0, __NR_sigreturn
		 *         syscall
		 */
		err |= __put_user(0x24020000 + __NR_sigreturn,
		                  frame->sf_code + 0);
		err |= __put_user(0x0000000c                 ,
		                  frame->sf_code + 1);
		flush_cache_sigtramp((unsigned long) frame->sf_code);
	}

	err |= setup_sigcontext(regs, &frame->sf_sc);
	err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
	if (err)
		goto give_sigsegv;

	/*
	 * Arguments to signal handler:
	 *
	 *   a0 = signal number
	 *   a1 = 0 (should be cause)
	 *   a2 = pointer to struct sigcontext
	 *
	 * $25 and c0_epc point to the signal handler, $29 points to the
	 * struct sigframe.
	 */
	regs->regs[ 4] = signr;
	regs->regs[ 5] = 0;
	regs->regs[ 6] = (unsigned long) &frame->sf_sc;
	regs->regs[29] = (unsigned long) frame;
	regs->regs[31] = (unsigned long) frame->sf_code;
	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;

#if DEBUG_SIG
	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%p ra=0x%p\n",
	       current->comm, current->pid, frame, regs->cp0_epc, frame->code);
#endif
        return;

give_sigsegv:
	if (signr == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	force_sig(SIGSEGV, current);
}

static void inline
setup_rt_frame(struct k_sigaction * ka, struct pt_regs *regs,
               int signr, sigset_t *set, siginfo_t *info)
{
	struct rt_sigframe *frame;
	int err = 0;

	frame = get_sigframe(ka, regs, sizeof(*frame));
	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
		goto give_sigsegv;

	/* Set up to return from userspace.  If provided, use a stub already
	   in userspace.  */
	if (ka->sa.sa_flags & SA_RESTORER)
		regs->regs[31] = (unsigned long) ka->sa.sa_restorer;
	else {
		/*
		 * Set up the return code ...
		 *
		 *         li      v0, __NR_sigreturn
		 *         syscall
		 */
		err |= __put_user(0x24020000 + __NR_sigreturn,
		                  frame->rs_code + 0);
		err |= __put_user(0x0000000c                 ,
		                  frame->rs_code + 1);
		flush_cache_sigtramp((unsigned long) frame->rs_code);
	}

	/* Create siginfo.  */
	err |= copy_siginfo_to_user(&frame->rs_info, info);

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->rs_uc.uc_flags);
	err |= __put_user(0, &frame->rs_uc.uc_link);
	err |= __put_user((void *)current->sas_ss_sp,
	                  &frame->rs_uc.uc_stack.ss_sp);
	err |= __put_user(sas_ss_flags(regs->regs[29]),
	                  &frame->rs_uc.uc_stack.ss_flags);
	err |= __put_user(current->sas_ss_size,
	                  &frame->rs_uc.uc_stack.ss_size);
	err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
	err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));

	if (err)
		goto give_sigsegv;

	/*
	 * Arguments to signal handler:
	 *
	 *   a0 = signal number
	 *   a1 = 0 (should be cause)
	 *   a2 = pointer to ucontext
	 *
	 * $25 and c0_epc point to the signal handler, $29 points to
	 * the struct rt_sigframe.
	 */
	regs->regs[ 4] = signr;
	regs->regs[ 5] = (unsigned long) &frame->rs_info;
	regs->regs[ 6] = (unsigned long) &frame->rs_uc;
	regs->regs[29] = (unsigned long) frame;
	regs->regs[31] = (unsigned long) frame->rs_code;
	regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;

#if DEBUG_SIG
	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%p ra=0x%p\n",
	       current->comm, current->pid, frame, regs->cp0_epc, frame->code);
#endif
	return;

give_sigsegv:
	if (signr == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	force_sig(SIGSEGV, current);
}

static inline void
handle_signal(unsigned long sig, struct k_sigaction *ka,
	siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
{
	if (ka->sa.sa_flags & SA_SIGINFO)
		setup_rt_frame(ka, regs, sig, oldset, info);
	else
		setup_frame(ka, regs, sig, oldset);

	if (ka->sa.sa_flags & SA_ONESHOT)
		ka->sa.sa_handler = SIG_DFL;
	if (!(ka->sa.sa_flags & SA_NODEFER)) {
		spin_lock_irq(&current->sigmask_lock);
		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
		sigaddset(&current->blocked,sig);
		recalc_sigpending(current);
		spin_unlock_irq(&current->sigmask_lock);
	}
}

static inline void
syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
{
	switch(regs->regs[0]) {
	case ERESTARTNOHAND:
		regs->regs[2] = EINTR;
		break;
	case ERESTARTSYS:
		if(!(ka->sa.sa_flags & SA_RESTART)) {
			regs->regs[2] = EINTR;
			break;
		}
	/* fallthrough */
	case ERESTARTNOINTR:		/* Userland will reload $v0.  */
		regs->regs[7] = regs->regs[26];
		regs->cp0_epc -= 8;
	}

	regs->regs[0] = 0;		/* Don't deal with this again.  */
}

extern int do_irix_signal(sigset_t *oldset, struct pt_regs *regs);

asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs)
{
	struct k_sigaction *ka;
	siginfo_t info;

#ifdef CONFIG_BINFMT_IRIX
	if (current->personality != PER_LINUX)
		return do_irix_signal(oldset, regs);
#endif

	if (!oldset)
		oldset = &current->blocked;

	for (;;) {
		unsigned long signr;

		spin_lock_irq(&current->sigmask_lock);
		signr = dequeue_signal(&current->blocked, &info);
		spin_unlock_irq(&current->sigmask_lock);

		if (!signr)
			break;

		if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
			/* Let the debugger run.  */
			current->exit_code = signr;
			current->state = TASK_STOPPED;
			notify_parent(current, SIGCHLD);
			schedule();

			/* We're back.  Did the debugger cancel the sig?  */
			if (!(signr = current->exit_code))
				continue;
			current->exit_code = 0;

			/* The debugger continued.  Ignore SIGSTOP.  */
			if (signr == SIGSTOP)
				continue;

			/* Update the siginfo structure.  Is this good?  */
			if (signr != info.si_signo) {
				info.si_signo = signr;
				info.si_errno = 0;
				info.si_code = SI_USER;
				info.si_pid = current->p_pptr->pid;
				info.si_uid = current->p_pptr->uid;
			}

			/* If the (new) signal is now blocked, requeue it.  */
			if (sigismember(&current->blocked, signr)) {
				send_sig_info(signr, &info, current);
				continue;
			}
		}

		ka = &current->sig->action[signr-1];
		if (ka->sa.sa_handler == SIG_IGN) {
			if (signr != SIGCHLD)
				continue;
			/* Check for SIGCHLD: it's special.  */
			while (sys_wait4(-1, NULL, WNOHANG, NULL) > 0)
				/* nothing */;
			continue;
		}

		if (ka->sa.sa_handler == SIG_DFL) {
			int exit_code = signr;

			/* Init gets no signals it doesn't want.  */
			if (current->pid == 1)
				continue;

			switch (signr) {
			case SIGCONT: case SIGCHLD: case SIGWINCH:
				continue;

			case SIGTSTP: case SIGTTIN: case SIGTTOU:
				if (is_orphaned_pgrp(current->pgrp))
					continue;
				/* FALLTHRU */

			case SIGSTOP:
				current->state = TASK_STOPPED;
				current->exit_code = signr;
				if (!(current->p_pptr->sig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
					notify_parent(current, SIGCHLD);
				schedule();
				continue;

			case SIGQUIT: case SIGILL: case SIGTRAP:
			case SIGABRT: case SIGFPE: case SIGSEGV:
			case SIGBUS: case SIGSYS: case SIGXCPU: case SIGXFSZ:
				if (do_coredump(signr, regs))
					exit_code |= 0x80;
				/* FALLTHRU */

			default:
				sigaddset(&current->pending.signal, signr);
				recalc_sigpending(current);
				current->flags |= PF_SIGNALED;
				do_exit(exit_code);
				/* NOTREACHED */
			}
		}

		if (regs->regs[0])
			syscall_restart(regs, ka);
		/* Whee!  Actually deliver the signal.  */
		handle_signal(signr, ka, &info, oldset, regs);
		return 1;
	}

	/*
	 * Who's code doesn't conform to the restartable syscall convention
	 * dies here!!!  The li instruction, a single machine instruction,
	 * must directly be followed by the syscall instruction.
	 */
	if (regs->regs[0]) {
		if (regs->regs[2] == ERESTARTNOHAND ||
		    regs->regs[2] == ERESTARTSYS ||
		    regs->regs[2] == ERESTARTNOINTR) {
			regs->regs[7] = regs->regs[26];
			regs->cp0_epc -= 8;
		}
	}
	return 0;
}