signal.c

优龙2410linux2.6.8内核源代码

restore_sigmask(sigset_t *set)
{
	sigdelsetmask(set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);
	current->blocked = *set;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
}

/*
 * Set up a signal frame for a "real-time" signal handler
 * (one which gets siginfo).
 */
static void
handle_rt_signal(unsigned long sig, struct k_sigaction *ka,
		 siginfo_t *info, sigset_t *oldset, struct pt_regs * regs,
		 unsigned long newsp)
{
	struct rt_sigframe __user *rt_sf;
	struct mcontext __user *frame;
	unsigned long origsp = newsp;

	/* Set up Signal Frame */
	/* Put a Real Time Context onto stack */
	newsp -= sizeof(*rt_sf);
	rt_sf = (struct rt_sigframe __user *) newsp;

	/* create a stack frame for the caller of the handler */
	newsp -= __SIGNAL_FRAMESIZE + 16;

	if (verify_area(VERIFY_WRITE, (void __user *) newsp, origsp - newsp))
		goto badframe;

	/* Put the siginfo & fill in most of the ucontext */
	if (copy_siginfo_to_user(&rt_sf->info, info)
	    || __put_user(0, &rt_sf->uc.uc_flags)
	    || __put_user(0, &rt_sf->uc.uc_link)
	    || __put_user(current->sas_ss_sp, &rt_sf->uc.uc_stack.ss_sp)
	    || __put_user(sas_ss_flags(regs->gpr[1]),
			  &rt_sf->uc.uc_stack.ss_flags)
	    || __put_user(current->sas_ss_size, &rt_sf->uc.uc_stack.ss_size)
	    || __put_user(&rt_sf->uc.uc_mcontext, &rt_sf->uc.uc_regs)
	    || __copy_to_user(&rt_sf->uc.uc_sigmask, oldset, sizeof(*oldset)))
		goto badframe;

	/* Save user registers on the stack */
	frame = &rt_sf->uc.uc_mcontext;
	if (save_user_regs(regs, frame, __NR_rt_sigreturn))
		goto badframe;

	if (put_user(regs->gpr[1], (unsigned long __user *)newsp))
		goto badframe;
	regs->gpr[1] = newsp;
	regs->gpr[3] = sig;
	regs->gpr[4] = (unsigned long) &rt_sf->info;
	regs->gpr[5] = (unsigned long) &rt_sf->uc;
	regs->gpr[6] = (unsigned long) rt_sf;
	regs->nip = (unsigned long) ka->sa.sa_handler;
	regs->link = (unsigned long) frame->tramp;
	regs->trap = 0;

	return;

badframe:
#ifdef DEBUG_SIG
	printk("badframe in handle_rt_signal, regs=%p frame=%p newsp=%lx\n",
	       regs, frame, newsp);
#endif
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	force_sig(SIGSEGV, current);
}

static int do_setcontext(struct ucontext __user *ucp, struct pt_regs *regs, int sig)
{
	sigset_t set;
	struct mcontext __user *mcp;

	if (__copy_from_user(&set, &ucp->uc_sigmask, sizeof(set))
	    || __get_user(mcp, &ucp->uc_regs))
		return -EFAULT;
	restore_sigmask(&set);
	if (restore_user_regs(regs, mcp, sig))
		return -EFAULT;

	return 0;
}

int sys_swapcontext(struct ucontext __user *old_ctx,
		    struct ucontext __user *new_ctx,
		    int ctx_size, int r6, int r7, int r8, struct pt_regs *regs)
{
	unsigned char tmp;

	/* Context size is for future use. Right now, we only make sure
	 * we are passed something we understand
	 */
	if (ctx_size < sizeof(struct ucontext))
		return -EINVAL;

	if (old_ctx != NULL) {
		if (verify_area(VERIFY_WRITE, old_ctx, sizeof(*old_ctx))
		    || save_user_regs(regs, &old_ctx->uc_mcontext, 0)
		    || __copy_to_user(&old_ctx->uc_sigmask,
				      &current->blocked, sizeof(sigset_t))
		    || __put_user(&old_ctx->uc_mcontext, &old_ctx->uc_regs))
			return -EFAULT;
	}
	if (new_ctx == NULL)
		return 0;
	if (verify_area(VERIFY_READ, new_ctx, sizeof(*new_ctx))
	    || __get_user(tmp, (u8 __user *) new_ctx)
	    || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 1))
		return -EFAULT;

	/*
	 * If we get a fault copying the context into the kernel's
	 * image of the user's registers, we can't just return -EFAULT
	 * because the user's registers will be corrupted.  For instance
	 * the NIP value may have been updated but not some of the
	 * other registers.  Given that we have done the verify_area
	 * and successfully read the first and last bytes of the region
	 * above, this should only happen in an out-of-memory situation
	 * or if another thread unmaps the region containing the context.
	 * We kill the task with a SIGSEGV in this situation.
	 */
	if (do_setcontext(new_ctx, regs, 0))
		do_exit(SIGSEGV);
	sigreturn_exit(regs);
	/* doesn't actually return back to here */
	return 0;
}

int sys_rt_sigreturn(int r3, int r4, int r5, int r6, int r7, int r8,
		     struct pt_regs *regs)
{
	struct rt_sigframe __user *rt_sf;

	/* Always make any pending restarted system calls return -EINTR */
	current_thread_info()->restart_block.fn = do_no_restart_syscall;

	rt_sf = (struct rt_sigframe __user *)
		(regs->gpr[1] + __SIGNAL_FRAMESIZE + 16);
	if (verify_area(VERIFY_READ, rt_sf, sizeof(struct rt_sigframe)))
		goto bad;
	if (do_setcontext(&rt_sf->uc, regs, 1))
		goto bad;

	/*
	 * It's not clear whether or why it is desirable to save the
	 * sigaltstack setting on signal delivery and restore it on
	 * signal return.  But other architectures do this and we have
	 * always done it up until now so it is probably better not to
	 * change it.  -- paulus
	 */
	do_sigaltstack(&rt_sf->uc.uc_stack, NULL, regs->gpr[1]);

	sigreturn_exit(regs);		/* doesn't return here */
	return 0;

 bad:
	force_sig(SIGSEGV, current);
	return 0;
}

/*
 * 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,
	      unsigned long newsp)
{
	struct sigcontext __user *sc;
	struct sigregs __user *frame;
	unsigned long origsp = newsp;

	/* Set up Signal Frame */
	newsp -= sizeof(struct sigregs);
	frame = (struct sigregs __user *) newsp;

	/* Put a sigcontext on the stack */
	newsp -= sizeof(*sc);
	sc = (struct sigcontext __user *) newsp;

	/* create a stack frame for the caller of the handler */
	newsp -= __SIGNAL_FRAMESIZE;

	if (verify_area(VERIFY_WRITE, (void __user *) newsp, origsp - newsp))
		goto badframe;

#if _NSIG != 64
#error "Please adjust handle_signal()"
#endif
	if (__put_user((unsigned long) ka->sa.sa_handler, &sc->handler)
	    || __put_user(oldset->sig[0], &sc->oldmask)
	    || __put_user(oldset->sig[1], &sc->_unused[3])
	    || __put_user((struct pt_regs *)frame, &sc->regs)
	    || __put_user(sig, &sc->signal))
		goto badframe;

	if (save_user_regs(regs, &frame->mctx, __NR_sigreturn))
		goto badframe;

	if (put_user(regs->gpr[1], (unsigned long __user *)newsp))
		goto badframe;
	regs->gpr[1] = newsp;
	regs->gpr[3] = sig;
	regs->gpr[4] = (unsigned long) sc;
	regs->nip = (unsigned long) ka->sa.sa_handler;
	regs->link = (unsigned long) frame->mctx.tramp;
	regs->trap = 0;

	return;

badframe:
#ifdef DEBUG_SIG
	printk("badframe in handle_signal, regs=%p frame=%p newsp=%lx\n",
	       regs, frame, newsp);
#endif
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	force_sig(SIGSEGV, current);
}

/*
 * Do a signal return; undo the signal stack.
 */
int sys_sigreturn(int r3, int r4, int r5, int r6, int r7, int r8,
		  struct pt_regs *regs)
{
	struct sigcontext __user *sc;
	struct sigcontext sigctx;
	struct mcontext __user *sr;
	sigset_t set;

	/* Always make any pending restarted system calls return -EINTR */
	current_thread_info()->restart_block.fn = do_no_restart_syscall;

	sc = (struct sigcontext __user *)(regs->gpr[1] + __SIGNAL_FRAMESIZE);
	if (copy_from_user(&sigctx, sc, sizeof(sigctx)))
		goto badframe;

	set.sig[0] = sigctx.oldmask;
	set.sig[1] = sigctx._unused[3];
	restore_sigmask(&set);

	sr = (struct mcontext __user *) sigctx.regs;
	if (verify_area(VERIFY_READ, sr, sizeof(*sr))
	    || restore_user_regs(regs, sr, 1))
		goto badframe;

	sigreturn_exit(regs);		/* doesn't return */
	return 0;

badframe:
	force_sig(SIGSEGV, current);
	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.
 */
int do_signal(sigset_t *oldset, struct pt_regs *regs)
{
	siginfo_t info;
	struct k_sigaction *ka;
	unsigned long frame, newsp;
	int signr, ret;

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

	newsp = frame = 0;

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

	ka = (signr == 0)? NULL: &current->sighand->action[signr-1];

	if (TRAP(regs) == 0x0C00		/* System Call! */
	    && regs->ccr & 0x10000000		/* error signalled */
	    && ((ret = regs->gpr[3]) == ERESTARTSYS
		|| ret == ERESTARTNOHAND || ret == ERESTARTNOINTR
		|| ret == ERESTART_RESTARTBLOCK)) {

		if (signr > 0
		    && (ret == ERESTARTNOHAND || ret == ERESTART_RESTARTBLOCK
			|| (ret == ERESTARTSYS
			    && !(ka->sa.sa_flags & SA_RESTART)))) {
			/* make the system call return an EINTR error */
			regs->result = -EINTR;
			regs->gpr[3] = EINTR;
			/* note that the cr0.SO bit is already set */
		} else {
			regs->nip -= 4;	/* Back up & retry system call */
			regs->result = 0;
			regs->trap = 0;
			if (ret == ERESTART_RESTARTBLOCK)
				regs->gpr[0] = __NR_restart_syscall;
			else
				regs->gpr[3] = regs->orig_gpr3;
		}
	}

	if (signr == 0)
		return 0;		/* no signals delivered */

	if ((ka->sa.sa_flags & SA_ONSTACK) && current->sas_ss_size
	    && !on_sig_stack(regs->gpr[1]))
		newsp = current->sas_ss_sp + current->sas_ss_size;
	else
		newsp = regs->gpr[1];
	newsp &= ~0xfUL;

	/* Whee!  Actually deliver the signal.  */
	if (ka->sa.sa_flags & SA_SIGINFO)
		handle_rt_signal(signr, ka, &info, oldset, regs, newsp);
	else
		handle_signal(signr, ka, &info, oldset, regs, newsp);

	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, signr);
		recalc_sigpending();
		spin_unlock_irq(&current->sighand->siglock);
	}

	return 1;
}