signal.c

linux-2.4.29操作系统的源码

	return regs->result;

badframe:
	do_exit(SIGSEGV);
}

static void
setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
		sigset_t *set, struct pt_regs *regs)
{
	/* Handler is *really* a pointer to the function descriptor for
	 * the signal routine.  The first entry in the function
	 * descriptor is the entry address of signal and the second
	 * entry is the TOC value we need to use.
	 */
	func_descr_t *funct_desc_ptr;
	struct rt_sigframe *frame;
	unsigned long newsp;
	int err = 0;

	frame = get_sigframe(ka, regs, sizeof(*frame));

	if (verify_area(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;

	err |= __put_user(&frame->info, &frame->pinfo);
	err |= __put_user(&frame->uc, &frame->puc);
	err |= copy_siginfo_to_user(&frame->info, info);
	if (err)
		goto give_sigsegv;

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(0, &frame->uc.uc_link);
	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
	err |= __put_user(sas_ss_flags(regs->gpr[1]),
			  &frame->uc.uc_stack.ss_flags);
	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL,
				(unsigned long)ka->sa.sa_handler);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
	if (err)
		goto give_sigsegv;

	/* Set up to return from userspace. */
	err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
	if (err)
		goto give_sigsegv;

	funct_desc_ptr = (func_descr_t *) ka->sa.sa_handler;

	/* Allocate a dummy caller frame for the signal handler. */
	newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE;
	err |= put_user(0, (unsigned long *)newsp);

	/* Set up "regs" so we "return" to the signal handler. */
	err |= get_user(regs->nip, &funct_desc_ptr->entry);
	regs->link = (unsigned long) &frame->tramp[0];
	regs->gpr[1] = newsp;
	err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
	regs->gpr[3] = signr;
	err |= get_user(regs->gpr[4], (unsigned long *)&frame->pinfo);
	err |= get_user(regs->gpr[5], (unsigned long *)&frame->puc);
	regs->gpr[6] = (unsigned long) frame;
	if (err)
		goto give_sigsegv;

	return;

give_sigsegv:
#if DEBUG_SIG
	printk("badframe in setup_rt_frame, regs=%p frame=%p, newsp=0x%lx\n",
		regs, frame, newsp);
#endif
	do_exit(SIGSEGV);
}

/*
 * Do a signal return; undo the signal stack.
 */
asmlinkage long
sys_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
	      unsigned long r6, unsigned long r7, unsigned long r8,
	      struct pt_regs *regs)
{
	struct sigcontext *sc = (struct sigcontext *)regs->gpr[1];
	sigset_t set;

	if (verify_area(VERIFY_READ, sc, sizeof(*sc)))
		goto badframe;

	if (restore_sigcontext(regs, &set, sc))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sigmask_lock);
	current->blocked = set;
	recalc_sigpending(current);
	spin_unlock_irq(&current->sigmask_lock);

	return regs->result;

badframe:
	do_exit(SIGSEGV);
}	


static void
setup_frame(int signr, struct k_sigaction *ka, sigset_t *set,
	    struct pt_regs *regs)
{
	/* Handler is *really* a pointer to the function descriptor for
	 * the signal routine.  The first entry in the function
	 * descriptor is the entry address of signal and the second
	 * entry is the TOC value we need to use.
	 */
	func_descr_t *funct_desc_ptr;
	struct sigframe *frame;
	unsigned long newsp;
	int err = 0;

	frame = get_sigframe(ka, regs, sizeof(*frame));

	if (verify_area(VERIFY_WRITE, frame, sizeof(*frame)))
		goto badframe;

	err |= setup_sigcontext(&frame->sc, regs, signr, set,
				(unsigned long)ka->sa.sa_handler);

	/* Set up to return from userspace. */
	err |= setup_trampoline(__NR_sigreturn, &frame->tramp[0]);
	if (err)
		goto badframe;

	funct_desc_ptr = (func_descr_t *) ka->sa.sa_handler;

	/* Allocate a dummy caller frame for the signal handler. */
	newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE;
	err |= put_user(0, (unsigned long *)newsp);

	/* Set up "regs" so we "return" to the signal handler. */
	err |= get_user(regs->nip, &funct_desc_ptr->entry);
	regs->link = (unsigned long) &frame->tramp[0];
	regs->gpr[1] = newsp;
	err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
	regs->gpr[3] = signr;
	regs->gpr[4] = (unsigned long) &frame->sc;
	if (err)
		goto badframe;

	return;

badframe:
#if DEBUG_SIG
	printk("badframe in setup_frame, regs=%p frame=%p newsp=%lx\n",
	       regs, frame, newsp);
#endif
	do_exit(SIGSEGV);
}

/*
 * OK, we're invoking a handler
 */
static void
handle_signal(unsigned long sig, struct k_sigaction *ka,
	      siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
{
	/* Set up Signal Frame */
	if (ka->sa.sa_flags & SA_SIGINFO)
		setup_rt_frame(sig, ka, info, oldset, regs);
	else
		setup_frame(sig, ka, oldset, regs);

	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 ((int)regs->result) {
		case -ERESTARTNOHAND:
			/* ERESTARTNOHAND means that the syscall should only
			   be restarted if there was no handler for the signal,
			   and since we only get here if there is a handler,
			   we dont restart */
			regs->result = -EINTR;
			break;

		case -ERESTARTSYS:
			/* ERESTARTSYS means to restart the syscall if there is
			   no handler or the handler was registered with SA_RESTART */
			if (!(ka->sa.sa_flags & SA_RESTART)) {
				regs->result = -EINTR;
				break;
			}
		/* fallthrough */
		case -ERESTARTNOINTR:
			/* ERESTARTNOINTR means that the syscall should be
			   called again after the signal handler returns */
			regs->gpr[3] = regs->orig_gpr3;
			regs->nip -= 4;
			regs->result = 0;
	}
}

static int
get_signal_to_deliver(siginfo_t *info, struct pt_regs *regs)
{
	for (;;) {
		unsigned long signr;
		struct k_sigaction *ka;

		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?  */
			signr = current->exit_code;
			if (signr == 0)
				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: case SIGURG:
				continue;

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

			case SIGSTOP: {
				struct signal_struct *sig;
				current->state = TASK_STOPPED;
				current->exit_code = signr;
				sig = current->p_pptr->sig;
				if (sig && !(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:
				sig_exit(signr, exit_code, info);
				/* NOTREACHED */
			}
		}
		return signr;
	}
	return 0;
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 */
extern int do_signal32(sigset_t *oldset, struct pt_regs *regs);

int
do_signal(sigset_t *oldset, struct pt_regs *regs)
{
	siginfo_t info;
	int signr;

	/*
	 * If the current thread is 32 bit - invoke the
	 * 32 bit signal handling code
	 */
	if (current->thread.flags & PPC_FLAG_32BIT)
		return do_signal32(oldset, regs);

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

	signr = get_signal_to_deliver(&info, regs);
	if (signr > 0) {
		struct k_sigaction *ka = &current->sig->action[signr-1];

		/* Whee!  Actually deliver the signal.  */
		if (regs->trap == 0x0C00)
			syscall_restart(regs, ka);
		handle_signal(signr, ka, &info, oldset, regs);
		return 1;
	}

	if (regs->trap == 0x0C00 /* System Call! */ &&
	    ((int)regs->result == -ERESTARTNOHAND ||
	     (int)regs->result == -ERESTARTSYS ||
	     (int)regs->result == -ERESTARTNOINTR)) {
		regs->gpr[3] = regs->orig_gpr3;
		regs->nip -= 4;		/* Back up & retry system call */
		regs->result = 0;
	}

	return 0;
}