signal32.c

来自「linux-2.4.29操作系统的源码」· C语言 代码 · 共 1,110 行 · 第 1/2 页

	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];

	/*
 	 * FPU emulator may have it's own trampoline active just
 	 * above the user stack, 16-bytes before the next lowest
 	 * 16 byte boundary.  Try to avoid trashing it.
 	 */
 	sp -= 32;

	/* This is the X/Open sanctioned signal stack switching.  */
	if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags (sp) == 0))
		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 the return code ...
	 *
	 *         li      v0, __NR_O32_sigreturn
	 *         syscall
	 */
	err |= __put_user(0x24020000 + __NR_O32_sigreturn, frame->sf_code + 0);
	err |= __put_user(0x0000000c                     , frame->sf_code + 1);
	flush_cache_sigtramp((unsigned long) frame->sf_code);

	err |= setup_sigcontext32(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%lx ra=0x%p\n",
	       current->comm, current->pid,
	       frame, regs->cp0_epc, frame->sf_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_sigframe32 *frame;
	int err = 0;
	s32 sp;

	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.  */
	/*
	 * Set up the return code ...
	 *
	 *         li      v0, __NR_O32_rt_sigreturn
	 *         syscall
	 */
	err |= __put_user(0x24020000 + __NR_O32_rt_sigreturn, frame->rs_code + 0);
	err |= __put_user(0x0000000c                      , frame->rs_code + 1);
	flush_cache_sigtramp((unsigned long) frame->rs_code);

	/* Convert (siginfo_t -> siginfo_t32) and copy to user. */
	err |= copy_siginfo_to_user32(&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);
	sp = (int) (long) current->sas_ss_sp;
	err |= __put_user(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_sigcontext32(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_sigframe32.
	 */
	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%lx ra=0x%p\n",
	       current->comm, current->pid,
	       frame, regs->cp0_epc, frame->rs_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.  */
}

asmlinkage int do_signal32(sigset_t *oldset, struct pt_regs *regs)
{
	struct k_sigaction *ka;
	siginfo_t info;

	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: case SIGURG:
				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 */
			}
		}

		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;
}

extern asmlinkage int sys_sigprocmask(int how, old_sigset_t *set,
						old_sigset_t *oset);

asmlinkage int sys32_sigprocmask(int how, old_sigset_t32 *set,
				 old_sigset_t32 *oset)
{
	old_sigset_t s;
	int ret;
	mm_segment_t old_fs = get_fs();

	if (set && get_user (s, set))
		return -EFAULT;

	set_fs (KERNEL_DS);
	ret = sys_sigprocmask(how, set ? &s : NULL, oset ? &s : NULL);
	set_fs (old_fs);

	if (!ret && oset && put_user (s, oset))
		return -EFAULT;

	return ret;
}

asmlinkage long sys_sigpending(old_sigset_t *set);

asmlinkage int sys32_sigpending(old_sigset_t32 *set)
{
	old_sigset_t pending;
	int ret;
	mm_segment_t old_fs = get_fs();

	set_fs (KERNEL_DS);
	ret = sys_sigpending(&pending);
	set_fs (old_fs);

	if (put_user(pending, set))
		return -EFAULT;

	return ret;
}

asmlinkage int sys32_rt_sigaction(int sig, const struct sigaction32 *act,
				  struct sigaction32 *oact,
				  unsigned int sigsetsize)
{
	struct k_sigaction new_sa, old_sa;
	int ret = -EINVAL;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		goto out;

	if (act) {
		int err = 0;

		if (!access_ok(VERIFY_READ, act, sizeof(*act)))
			return -EFAULT;
		err |= __get_user((u32)(u64)new_sa.sa.sa_handler,
		                  &act->sa_handler);
		err |= __get_user(new_sa.sa.sa_flags, &act->sa_flags);
		err |= get_sigset(&new_sa.sa.sa_mask, &act->sa_mask);
		if (err)
			return -EFAULT;
	}

	ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);

	if (!ret && oact) {
		int err = 0;

		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
			return -EFAULT;

		err |= __put_user((u32)(u64)old_sa.sa.sa_handler,
		                   &oact->sa_handler);
		err |= __put_user(old_sa.sa.sa_flags, &oact->sa_flags);
		err |= put_sigset(&old_sa.sa.sa_mask, &oact->sa_mask);
		if (err)
			return -EFAULT;
	}
out:
	return ret;
}

asmlinkage long sys_rt_sigprocmask(int how, sigset_t *set, sigset_t *oset,
				   size_t sigsetsize);

asmlinkage int sys32_rt_sigprocmask(int how, sigset32_t *set, sigset32_t *oset,
				    unsigned int sigsetsize)
{
	sigset_t old_set, new_set;
	int ret;
	mm_segment_t old_fs = get_fs();

	if (set && get_sigset(&new_set, set))
		return -EFAULT;

	set_fs (KERNEL_DS);
	ret = sys_rt_sigprocmask(how, set ? &new_set : NULL,
				 oset ? &old_set : NULL, sigsetsize);
	set_fs (old_fs);

	if (!ret && oset && put_sigset(&old_set, oset))
		return -EFAULT;

	return ret;
}

asmlinkage long sys_rt_sigpending(sigset_t *set, size_t sigsetsize);

asmlinkage int sys32_rt_sigpending(sigset32_t *uset, unsigned int sigsetsize)
{
	int ret;
	sigset_t set;
	mm_segment_t old_fs = get_fs();

	set_fs (KERNEL_DS);
	ret = sys_rt_sigpending(&set, sigsetsize);
	set_fs (old_fs);

	if (!ret && put_sigset(&set, uset))
		return -EFAULT;

	return ret;
}

struct timespec32 {
	int	tv_sec;
	int	tv_nsec;
};

asmlinkage int sys32_rt_sigtimedwait(sigset_t32 *uthese, siginfo_t32 *uinfo,
	struct timespec32 *uts, __kernel_size_t32 sigsetsize)
{
	int ret, sig;
	sigset_t these;
	sigset_t32 these32;
	struct timespec ts;
	siginfo_t info;
	long timeout = 0;

	/*
	 * As the result of a brainfarting competition a few years ago the
	 * size of sigset_t for the 32-bit kernel was choosen to be 128 bits
	 * but nothing so far is actually using that many, 64 are enough.  So
	 * for now we just drop the high bits.
	 */
	if (copy_from_user (&these32, uthese, sizeof(old_sigset_t32)))
		return -EFAULT;

	switch (_NSIG_WORDS) {
#ifdef __MIPSEB__
	case 4: these.sig[3] = these32.sig[6] | (((long)these32.sig[7]) << 32);
	case 3: these.sig[2] = these32.sig[4] | (((long)these32.sig[5]) << 32);
	case 2: these.sig[1] = these32.sig[2] | (((long)these32.sig[3]) << 32);
	case 1: these.sig[0] = these32.sig[0] | (((long)these32.sig[1]) << 32);
#endif
#ifdef __MIPSEL__
	case 4: these.sig[3] = these32.sig[7] | (((long)these32.sig[6]) << 32);
	case 3: these.sig[2] = these32.sig[5] | (((long)these32.sig[4]) << 32);
	case 2: these.sig[1] = these32.sig[3] | (((long)these32.sig[2]) << 32);
	case 1: these.sig[0] = these32.sig[1] | (((long)these32.sig[0]) << 32);
#endif
	}

	/*
	 * Invert the set of allowed signals to get those we
	 * want to block.
	 */
	sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
	signotset(&these);

	if (uts) {
		if (get_user (ts.tv_sec, &uts->tv_sec) ||
		    get_user (ts.tv_nsec, &uts->tv_nsec))
			return -EINVAL;
		if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
		    || ts.tv_sec < 0)
			return -EINVAL;
	}

	spin_lock_irq(&current->sigmask_lock);
	sig = dequeue_signal(&these, &info);
	if (!sig) {
		/* None ready -- temporarily unblock those we're interested
		   in so that we'll be awakened when they arrive.  */
		sigset_t oldblocked = current->blocked;
		sigandsets(&current->blocked, &current->blocked, &these);
		recalc_sigpending(current);
		spin_unlock_irq(&current->sigmask_lock);

		timeout = MAX_SCHEDULE_TIMEOUT;
		if (uts)
			timeout = (timespec_to_jiffies(&ts)
				   + (ts.tv_sec || ts.tv_nsec));

		current->state = TASK_INTERRUPTIBLE;
		timeout = schedule_timeout(timeout);

		spin_lock_irq(&current->sigmask_lock);
		sig = dequeue_signal(&these, &info);
		current->blocked = oldblocked;
		recalc_sigpending(current);
	}
	spin_unlock_irq(&current->sigmask_lock);

	if (sig) {
		ret = sig;
		if (uinfo) {
			if (copy_siginfo_to_user32(uinfo, &info))
				ret = -EFAULT;
		}
	} else {
		ret = -EAGAIN;
		if (timeout)
			ret = -EINTR;
	}

	return ret;
}

extern asmlinkage int sys_rt_sigqueueinfo(int pid, int sig, siginfo_t *uinfo);

asmlinkage int sys32_rt_sigqueueinfo(int pid, int sig, siginfo_t32 *uinfo)
{
	siginfo_t info;
	int ret;
	mm_segment_t old_fs = get_fs();

	if (copy_from_user (&info, uinfo, 3*sizeof(int)) ||
	    copy_from_user (info._sifields._pad, uinfo->_sifields._pad, SI_PAD_SIZE))
		return -EFAULT;
	set_fs (KERNEL_DS);
	ret = sys_rt_sigqueueinfo(pid, sig, &info);
	set_fs (old_fs);
	return ret;
}