signal.c

优龙2410linux2.6.8内核源代码

	unsigned long sp = regs->ARM_sp;

	/*
	 * 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 __user *)((sp - framesize) & ~7);
}

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

	/*
	 * 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 |= PSR_T_BIT;
		else
			cpsr &= ~PSR_T_BIT;
	}
#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;

		/*
		 * Ensure that the instruction cache sees
		 * the return code written onto the stack.
		 */
		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;
	regs->ARM_cpsr = cpsr;

	return 0;
}

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

	__put_user_error(0, &frame->uc.uc_flags, err);
	__put_user_error(NULL, &frame->uc.uc_link, err);

	memset(&stack, 0, sizeof(stack));
	stack.ss_sp = (void __user *)current->sas_ss_sp;
	stack.ss_flags = sas_ss_flags(regs->ARM_sp);
	stack.ss_size = current->sas_ss_size;
	err |= __copy_to_user(&frame->uc.uc_stack, &stack, sizeof(stack));

	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->info;
		regs->ARM_r2 = (unsigned long)&frame->uc;
	}

	return err;
}

static inline void restart_syscall(struct pt_regs *regs)
{
	regs->ARM_r0 = regs->ARM_ORIG_r0;
	regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
}

/*
 * OK, we're invoking a handler
 */	
static void
handle_signal(unsigned long sig, siginfo_t *info, sigset_t *oldset,
	      struct pt_regs * regs, int syscall)
{
	struct thread_info *thread = current_thread_info();
	struct task_struct *tsk = current;
	struct k_sigaction *ka = &tsk->sighand->action[sig-1];
	int usig = sig;
	int ret;

	/*
	 * If we were from a system call, check for system call restarting...
	 */
	if (syscall) {
		switch (regs->ARM_r0) {
		case -ERESTART_RESTARTBLOCK:
		case -ERESTARTNOHAND:
			regs->ARM_r0 = -EINTR;
			break;
		case -ERESTARTSYS:
			if (!(ka->sa.sa_flags & SA_RESTART)) {
				regs->ARM_r0 = -EINTR;
				break;
			}
			/* fallthrough */
		case -ERESTARTNOINTR:
			restart_syscall(regs);
		}
	}

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

	/*
	 * Block the signal if we were unsuccessful.
	 */
	if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
		spin_lock_irq(&tsk->sighand->siglock);
		sigorsets(&tsk->blocked, &tsk->blocked,
			  &ka->sa.sa_mask);
		sigaddset(&tsk->blocked, sig);
		recalc_sigpending();
		spin_unlock_irq(&tsk->sighand->siglock);
	}

	if (ret == 0) {
		if (ka->sa.sa_flags & SA_ONESHOT)
			ka->sa.sa_handler = SIG_DFL;
		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.
 */
static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
{
	siginfo_t info;
	int signr;

	/*
	 * 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 (current->flags & PF_FREEZE) {
		refrigerator(0);
		goto no_signal;
	}

	if (current->ptrace & PT_SINGLESTEP)
		ptrace_cancel_bpt(current);

	signr = get_signal_to_deliver(&info, regs, NULL);
	if (signr > 0) {
		handle_signal(signr, &info, oldset, regs, syscall);
		if (current->ptrace & PT_SINGLESTEP)
			ptrace_set_bpt(current);
		return 1;
	}

 no_signal:
	/*
	 * No signal to deliver to the process - restart the syscall.
	 */
	if (syscall) {
		if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
			if (thumb_mode(regs)) {
				regs->ARM_r7 = __NR_restart_syscall;
				regs->ARM_pc -= 2;
			} else {
				u32 __user *usp;

				regs->ARM_sp -= 12;
				usp = (u32 __user *)regs->ARM_sp;

				put_user(regs->ARM_pc, &usp[0]);
				/* swi __NR_restart_syscall */
				put_user(0xef000000 | __NR_restart_syscall, &usp[1]);
				/* ldr	pc, [sp], #12 */
				put_user(0xe49df00c, &usp[2]);

				flush_icache_range((unsigned long)usp,
						   (unsigned long)(usp + 3));

				regs->ARM_pc = regs->ARM_sp + 4;
			}
		}
		if (regs->ARM_r0 == -ERESTARTNOHAND ||
		    regs->ARM_r0 == -ERESTARTSYS ||
		    regs->ARM_r0 == -ERESTARTNOINTR) {
			restart_syscall(regs);
		}
	}
	if (current->ptrace & PT_SINGLESTEP)
		ptrace_set_bpt(current);
	return 0;
}

asmlinkage void
do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
	if (thread_flags & _TIF_SIGPENDING)
		do_signal(&current->blocked, regs, syscall);
}