signal.c

上传linux-jx2410的源代码

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

	/*
	 * ATPCS B01 mandates 8-byte alignment
	 */
	return (void *)((sp - framesize) & ~7);
}

static int
setup_return(struct pt_regs *regs, struct k_sigaction *ka,
	     unsigned long *rc, void *frame, int usig)
{
	unsigned long handler = (unsigned long)ka->sa.sa_handler;
	unsigned long retcode;
	int thumb = 0;
#ifdef CONFIG_CPU_32
	unsigned long cpsr = regs->ARM_cpsr;

	/*
	 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
	 */
	if (ka->sa.sa_flags & SA_THIRTYTWO)
		cpsr = (cpsr & ~MODE_MASK) | USR_MODE;

#ifdef CONFIG_ARM_THUMB
	if (elf_hwcap & HWCAP_THUMB) {
		/*
		 * The LSB of the handler determines if we're going to
		 * be using THUMB or ARM mode for this signal handler.
		 */
		thumb = handler & 1;

		if (thumb)
			cpsr |= T_BIT;
		else
			cpsr &= ~T_BIT;
	}
#endif
#endif

	if (ka->sa.sa_flags & SA_RESTORER) {
		retcode = (unsigned long)ka->sa.sa_restorer;
	} else {
		unsigned int idx = thumb;

		if (ka->sa.sa_flags & SA_SIGINFO)
			idx += 2;

		if (__put_user(retcodes[idx], rc))
			return 1;

		flush_icache_range((unsigned long)rc,
				   (unsigned long)(rc + 1));

		retcode = ((unsigned long)rc) + thumb;
	}

	regs->ARM_r0 = usig;
	regs->ARM_sp = (unsigned long)frame;
	regs->ARM_lr = retcode;
	regs->ARM_pc = handler & (thumb ? ~1 : ~3);

#ifdef CONFIG_CPU_32
	regs->ARM_cpsr = cpsr;
#endif

	return 0;
}

static int
setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
{
	struct sigframe *frame = get_sigframe(ka, regs, sizeof(*frame));
	int err = 0;

	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
		return 1;

	err |= setup_sigcontext(&frame->sc, /*&frame->fpstate,*/ regs, set->sig[0]);

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

	if (err == 0)
		err = setup_return(regs, ka, &frame->retcode, frame, usig);

	return err;
}

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

	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
		return 1;

	__put_user_error(&frame->info, &frame->pinfo, err);
	__put_user_error(&frame->uc, &frame->puc, err);
	err |= copy_siginfo_to_user(&frame->info, info);

	/* Clear all the bits of the ucontext we don't use.  */
	err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));

	err |= setup_sigcontext(&frame->uc.uc_mcontext, /*&frame->fpstate,*/
				regs, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	if (err == 0)
		err = setup_return(regs, ka, &frame->retcode, frame, usig);

	if (err == 0) {
		/*
		 * For realtime signals we must also set the second and third
		 * arguments for the signal handler.
		 *   -- Peter Maydell <[e-mail]> 2000-12-06
		 */
		regs->ARM_r1 = (unsigned long)frame->pinfo;
		regs->ARM_r2 = (unsigned long)frame->puc;
	}

	return err;
}

/*
 * 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)
{
	struct task_struct *tsk = current;
	int usig = sig;
	int ret;

	/*
	 * translate the signal
	 */
	if (usig < 32 && tsk->exec_domain && tsk->exec_domain->signal_invmap)
		usig = tsk->exec_domain->signal_invmap[usig];

	/*
	 * Set up the stack frame
	 */
	if (ka->sa.sa_flags & SA_SIGINFO)
		ret = setup_rt_frame(usig, ka, info, oldset, regs);
	else
		ret = setup_frame(usig, ka, oldset, regs);

	/*
	 * Check that the resulting registers are actually sane.
	 */
	ret |= !valid_user_regs(regs);

	if (ret == 0) {
		if (ka->sa.sa_flags & SA_ONESHOT)
			ka->sa.sa_handler = SIG_DFL;

		if (!(ka->sa.sa_flags & SA_NODEFER)) {
			spin_lock_irq(&tsk->sigmask_lock);
			sigorsets(&tsk->blocked, &tsk->blocked,
				  &ka->sa.sa_mask);
			sigaddset(&tsk->blocked, sig);
			recalc_sigpending(tsk);
			spin_unlock_irq(&tsk->sigmask_lock);
		}
		return;
	}

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

/*
 * 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, int syscall)
{
	struct k_sigaction *ka;
	siginfo_t info;
	int single_stepping;

	/*
	 * We want the common case to go fast, which
	 * is why we may in certain cases get here from
	 * kernel mode. Just return without doing anything
	 * if so.
	 */
	if (!user_mode(regs))
		return 0;

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

	single_stepping = ptrace_cancel_bpt(current);

	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();
			single_stepping |= ptrace_cancel_bpt(current);

			/* 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 */
			}
		}

		/* Are we from a system call? */
		if (syscall) {
			switch (regs->ARM_r0) {
			case -ERESTARTNOHAND:
				regs->ARM_r0 = -EINTR;
				break;

			case -ERESTARTSYS:
				if (!(ka->sa.sa_flags & SA_RESTART)) {
					regs->ARM_r0 = -EINTR;
					break;
				}
				/* fallthrough */
			case -ERESTARTNOINTR:
				regs->ARM_r0 = regs->ARM_ORIG_r0;
				regs->ARM_pc -= 4;
			}
		}
		/* Whee!  Actually deliver the signal.  */
		handle_signal(signr, ka, &info, oldset, regs);
		if (single_stepping)
		    	ptrace_set_bpt(current);
		return 1;
	}

	if (syscall &&
	    (regs->ARM_r0 == -ERESTARTNOHAND ||
	     regs->ARM_r0 == -ERESTARTSYS ||
	     regs->ARM_r0 == -ERESTARTNOINTR)) {
		regs->ARM_r0 = regs->ARM_ORIG_r0;
		regs->ARM_pc -= 4;
	}
	if (single_stepping)
		ptrace_set_bpt(current);
	return 0;
}