signal.c

优龙2410linux2.6.8内核源代码

	err |= __put_user(regs->er0, &gregs[0]);
	err |= __put_user(regs->er1, &gregs[1]);
	err |= __put_user(regs->er2, &gregs[2]);
	err |= __put_user(regs->er3, &gregs[3]);
	err |= __put_user(regs->er4, &gregs[4]);
	err |= __put_user(regs->er5, &gregs[5]);
	err |= __put_user(regs->er6, &gregs[6]);
	err |= __put_user(rdusp(), &gregs[7]);
	err |= __put_user(regs->pc, &gregs[8]);
	err |= __put_user(regs->ccr, &gregs[9]);
	return err;
}

static inline void *
get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
{
	unsigned long usp;

	/* Default to using normal stack.  */
	usp = rdusp();

	/* This is the X/Open sanctioned signal stack switching.  */
	if (ka->sa.sa_flags & SA_ONSTACK) {
		if (!on_sig_stack(usp))
			usp = current->sas_ss_sp + current->sas_ss_size;
	}
	return (void *)((usp - frame_size) & -8UL);
}

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

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

	if (_NSIG_WORDS > 1)
		err |= copy_to_user(frame->extramask, &set->sig[1],
				    sizeof(frame->extramask));

	setup_sigcontext(&context, regs, set->sig[0]);
	err |= copy_to_user (&frame->sc, &context, sizeof(context));

	/* Set up to return from userspace.  */
	err |= __put_user(frame->retcode, &frame->pretcode);

	/* sub.l er0,er0; mov.b #__NR_sigreturn,r0l; trapa #0 */
	err != __put_user(0x1a80f800 + (__NR_sigreturn & 0xff),
			(unsigned long *)(frame->retcode + 0));
	err |= __put_user(0x5700, (unsigned short *)(frame->retcode + 4));


	if (err)
		goto give_sigsegv;

	/* Set up registers for signal handler */
	wrusp ((unsigned long) frame);
	regs->pc = (unsigned long) ka->sa.sa_handler;
	regs->er0 = (current_thread_info()->exec_domain
			   && current_thread_info()->exec_domain->signal_invmap
			   && sig < 32
			   ? current_thread_info()->exec_domain->signal_invmap[sig]
		          : sig);
	regs->er1 = (unsigned long)&(frame->sc);
	regs->er5 = current->mm->start_data;	/* GOT base */

	return;

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

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

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

	err |= copy_siginfo_to_user(&frame->info, info);

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(0, &frame->uc.uc_link);
	err |= __put_user((void *)current->sas_ss_sp,
			  &frame->uc.uc_stack.ss_sp);
	err |= __put_user(sas_ss_flags(rdusp()),
			  &frame->uc.uc_stack.ss_flags);
	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
	err |= rt_setup_ucontext(&frame->uc, regs);
	err |= copy_to_user (&frame->uc.uc_sigmask, set, sizeof(*set));

	/* Set up to return from userspace.  */
	err |= __put_user(frame->retcode, &frame->pretcode);

	/* sub.l er0,er0; mov.b #__NR_rt_sigreturn,r0l; trapa #0 */
	err != __put_user(0x1a80f800 + (__NR_rt_sigreturn & 0xff),
			(long *)(frame->retcode + 0));
	err |= __put_user(0x5700, (short *)(frame->retcode + 4));

	if (err)
		goto give_sigsegv;

	/* Set up registers for signal handler */
	wrusp ((unsigned long) frame);
	regs->pc  = (unsigned long) ka->sa.sa_handler;
	regs->er0 = (current_thread_info()->exec_domain
		     && current_thread_info()->exec_domain->signal_invmap
		     && sig < 32
		     ? current_thread_info()->exec_domain->signal_invmap[sig]
		     : sig);
	regs->er1 = (unsigned long)&(frame->info);
	regs->er2 = (unsigned long)&frame->uc;
	regs->er5 = current->mm->start_data;	/* GOT base */

	return;

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

static inline void
handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
{
	switch (regs->er0) {
	case -ERESTARTNOHAND:
		if (!has_handler)
			goto do_restart;
		regs->er0 = -EINTR;
		break;

	case -ERESTARTSYS:
		if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
			regs->er0 = -EINTR;
			break;
		}
	/* fallthrough */
	case -ERESTARTNOINTR:
	do_restart:
		regs->er0 = regs->orig_er0;
		regs->pc -= 2;
		break;
	}
}

/*
 * OK, we're invoking a handler
 */
static void
handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
	      sigset_t *oldset, struct pt_regs *regs)
{
	/* are we from a system call? */
	if (regs->orig_er0 >= 0)
		/* If so, check system call restarting.. */
		handle_restart(regs, ka, 1);

	/* set up the stack 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->sighand->siglock);
		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
		sigaddset(&current->blocked,sig);
		recalc_sigpending();
		spin_unlock_irq(&current->sighand->siglock);
	}
}

/*
 * 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.
 *
 * Note that we go through the signals twice: once to check the signals
 * that the kernel can handle, and then we build all the user-level signal
 * handling stack-frames in one go after that.
 */
asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs)
{
	siginfo_t info;
	struct k_sigaction *ka;

	current->thread.esp0 = (unsigned long) regs;

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

	for (;;) {
		int signr;

		signr = get_signal_to_deliver(&info, regs, NULL);

		if (!signr)
			break;

		if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
			current->exit_code = signr;
			current->state = TASK_STOPPED;

			/* Did we come from a system call? */
			if (regs->orig_er0 >= 0) {
				/* Restart the system call the same way as
				   if the process were not traced.  */
				struct k_sigaction *ka =
					&current->sighand->action[signr-1];
				int has_handler =
					(ka->sa.sa_handler != SIG_IGN &&
					 ka->sa.sa_handler != SIG_DFL);
				handle_restart(regs, ka, has_handler);
			}
			notify_parent(current, SIGCHLD);
			schedule();

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

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

			/* 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->parent->pid;
				info.si_uid = current->parent->uid;
			}

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

		ka = &current->sighand->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;

			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(process_group(current)))
					continue;
				/* FALLTHRU */

			case SIGSTOP: {
				struct sighand_struct *sig;
				current->state = TASK_STOPPED;
				current->exit_code = signr;
                                sig = current->parent->sighand;
                                if (sig && !(sig->action[SIGCHLD-1].sa.sa_flags 
& SA_NOCLDSTOP))
                                        notify_parent(current, SIGCHLD);
				schedule();
				continue;
			}

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

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

		/* Whee!  Actually deliver the signal.  */
		handle_signal(signr, ka, &info, oldset, regs);
		return 1;
	}

	/* Did we come from a system call? */
	if (regs->orig_er0 >= 0)
		/* Restart the system call - no handlers present */
		handle_restart(regs, NULL, 0);

	return 0;
}