signal.c

来自「linux-2.4.29操作系统的源码」· C语言 代码 · 共 822 行 · 第 1/2 页

	COPY(tregs[0]);	COPY(tregs[1]);	COPY(tregs[2]);	COPY(tregs[3]);
	COPY(tregs[4]);	COPY(tregs[5]);	COPY(tregs[6]);	COPY(tregs[7]);
	COPY(sr);	COPY(pc);

#undef COPY

	err |= __put_user(mask, &sc->oldmask);

	return err;
}

/*
 * Determine which stack to use..
 */
static inline void *
get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
{
	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
		sp = current->sas_ss_sp + current->sas_ss_size;

	return (void *)((sp - frame_size) & -8ul);
}

void sa_default_restorer(void);		/* See comments below */
void sa_default_rt_restorer(void);	/* See comments below */

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

	frame = get_sigframe(ka, regs->regs[REG_SP], sizeof(*frame));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;

	signal = current->exec_domain
		&& current->exec_domain->signal_invmap
		&& sig < 32
		? current->exec_domain->signal_invmap[sig]
		: sig;

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

	/* Give up earlier as i386, in case */
	if (err)
		goto give_sigsegv;

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

	/* Give up earlier as i386, in case */
	if (err)
		goto give_sigsegv;

	/* Set up to return from userspace.  If provided, use a stub
	   already in userspace.  */
	if (ka->sa.sa_flags & SA_RESTORER) {
		DEREF_REG_PR = (unsigned long) ka->sa.sa_restorer | 0x1;

		/*
		 * On SH5 all edited pointers are subject to NEFF
		 */
		DEREF_REG_PR = (DEREF_REG_PR & NEFF_SIGN) ?
        		 	(DEREF_REG_PR | NEFF_MASK) : DEREF_REG_PR;
	} else {
		/*
		 * Different approach on SH5.
	         * . Endianness independent asm code gets placed in entry.S .
		 *   This is limited to four ASM instructions corresponding
		 *   to two long longs in size.
		 * . err checking is done on the else branch only
		 * . flush_icache_range() is called upon __put_user() only
		 * . all edited pointers are subject to NEFF
		 * . being code, linker turns ShMedia bit on, always
		 *   dereference index -1.
		 */
		DEREF_REG_PR = (unsigned long) frame->retcode | 0x01;
		DEREF_REG_PR = (DEREF_REG_PR & NEFF_SIGN) ?
        		 	(DEREF_REG_PR | NEFF_MASK) : DEREF_REG_PR;

		if (__copy_to_user(frame->retcode,
			(unsigned long long)sa_default_restorer & (~1), 16) != 0)
			goto give_sigsegv;

		/* Cohere the trampoline with the I-cache. */
		flush_cache_sigtramp(DEREF_REG_PR-1, DEREF_REG_PR-1+16);
	}

	/*
	 * Set up registers for signal handler.
	 * All edited pointers are subject to NEFF.
	 */
	regs->regs[REG_SP] = (unsigned long) frame;
	regs->regs[REG_SP] = (regs->regs[REG_SP] & NEFF_SIGN) ?
        		 (regs->regs[REG_SP] | NEFF_MASK) : regs->regs[REG_SP];
	regs->regs[REG_ARG1] = signal; /* Arg for signal handler */
	regs->regs[REG_ARG2] = (unsigned long long)(unsigned long)(signed long)&frame->sc;
	regs->pc = (unsigned long) ka->sa.sa_handler;
	regs->pc = (regs->pc & NEFF_SIGN) ? (regs->pc | NEFF_MASK) : regs->pc;

	set_fs(USER_DS);

#if DEBUG_SIG
	/* Broken %016Lx */
	printk("SIG deliver (#%d,%s:%d): sp=%p pc=%08Lx%08Lx link=%08Lx%08Lx\n",
		signal,
		current->comm, current->pid, frame,
		regs->pc >> 32, regs->pc & 0xffffffff,
		DEREF_REG_PR >> 32, DEREF_REG_PR & 0xffffffff);
#endif

	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;
	int signal;

	frame = get_sigframe(ka, regs->regs[REG_SP], sizeof(*frame));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;

	signal = current->exec_domain
		&& current->exec_domain->signal_invmap
		&& sig < 32
		? current->exec_domain->signal_invmap[sig]
		: sig;

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

	/* Give up earlier as i386, in case */
	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((void *)current->sas_ss_sp,
			  &frame->uc.uc_stack.ss_sp);
	err |= __put_user(sas_ss_flags(regs->regs[REG_SP]),
			  &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, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	/* Give up earlier as i386, in case */
	if (err)
		goto give_sigsegv;

	/* Set up to return from userspace.  If provided, use a stub
	   already in userspace.  */
	if (ka->sa.sa_flags & SA_RESTORER) {
		DEREF_REG_PR = (unsigned long) ka->sa.sa_restorer | 0x1;

		/*
		 * On SH5 all edited pointers are subject to NEFF
		 */
		DEREF_REG_PR = (DEREF_REG_PR & NEFF_SIGN) ?
        		 	(DEREF_REG_PR | NEFF_MASK) : DEREF_REG_PR;
	} else {
		/*
		 * Different approach on SH5.
	         * . Endianness independent asm code gets placed in entry.S .
		 *   This is limited to four ASM instructions corresponding
		 *   to two long longs in size.
		 * . err checking is done on the else branch only
		 * . flush_icache_range() is called upon __put_user() only
		 * . all edited pointers are subject to NEFF
		 * . being code, linker turns ShMedia bit on, always
		 *   dereference index -1.
		 */

		DEREF_REG_PR = (unsigned long) frame->retcode | 0x01;
		DEREF_REG_PR = (DEREF_REG_PR & NEFF_SIGN) ?
        		 	(DEREF_REG_PR | NEFF_MASK) : DEREF_REG_PR;

		if (__copy_to_user(frame->retcode,
			(unsigned long long)sa_default_rt_restorer & (~1), 16) != 0)
			goto give_sigsegv;

		flush_icache_range(DEREF_REG_PR-1, DEREF_REG_PR-1+15);
	}

	/*
	 * Set up registers for signal handler.
	 * All edited pointers are subject to NEFF.
	 */
	regs->regs[REG_SP] = (unsigned long) frame;
	regs->regs[REG_SP] = (regs->regs[REG_SP] & NEFF_SIGN) ?
        		 (regs->regs[REG_SP] | NEFF_MASK) : regs->regs[REG_SP];
	regs->regs[REG_ARG1] = signal; /* Arg for signal handler */
	regs->regs[REG_ARG2] = (unsigned long long)(unsigned long)(signed long)&frame->uc.uc_mcontext;
	regs->pc = (unsigned long) ka->sa.sa_handler;
	regs->pc = (regs->pc & NEFF_SIGN) ? (regs->pc | NEFF_MASK) : regs->pc;

	set_fs(USER_DS);

#if DEBUG_SIG
	/* Broken %016Lx */
	printk("SIG deliver (#%d,%s:%d): sp=%p pc=%08Lx%08Lx link=%08Lx%08Lx\n",
		signal,
		current->comm, current->pid, frame,
		regs->pc >> 32, regs->pc & 0xffffffff,
		DEREF_REG_PR >> 32, DEREF_REG_PR & 0xffffffff);
#endif

	return;

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

/*
 * 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)
{
	/* Are we from a system call? */
	if (regs->syscall_nr >= 0) {
		/* If so, check system call restarting.. */
		switch (regs->regs[REG_RET]) {
			case -ERESTARTNOHAND:
				regs->regs[REG_RET] = -EINTR;
				break;

			case -ERESTARTSYS:
				if (!(ka->sa.sa_flags & SA_RESTART)) {
					regs->regs[REG_RET] = -EINTR;
					break;
				}
			/* fallthrough */
			case -ERESTARTNOINTR:
				/* Decode syscall # */
				regs->regs[REG_RET] = regs->syscall_nr;
				regs->pc -= 4;
		}
	}

	/* 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->sigmask_lock);
		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
		sigaddset(&current->blocked,sig);
		recalc_sigpending(current);
		spin_unlock_irq(&current->sigmask_lock);
	}
}

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

	/*
	 * 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 1;

	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:
			        sig_exit(signr, exit_code, &info);
				/* NOTREACHED */ 
			}
		}

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

	/* Did we come from a system call? */
	if (regs->syscall_nr >= 0) {
		/* Restart the system call - no handlers present */
		if (regs->regs[REG_RET] == -ERESTARTNOHAND ||
		    regs->regs[REG_RET] == -ERESTARTSYS ||
		    regs->regs[REG_RET] == -ERESTARTNOINTR) {
			/* Decode Syscall # */
			regs->regs[REG_RET] = regs->syscall_nr;
			regs->pc -= 4;
		}
	}
	return 0;
}