signal.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

	return;

badframe:
#if DEBUG_SIG
	printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n",
	       regs, frame, newsp);
#endif
	do_exit(SIGSEGV);
}

/*
 * Do a signal return; undo the signal stack.
 */
long sys_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
		   unsigned long r6, unsigned long r7, unsigned long r8,
		   struct pt_regs *regs)
{
	struct sigcontext_struct *sc, sigctx;
	struct sigregs *sr;
	long ret;
	elf_gregset_t saved_regs;  /* an array of ELF_NGREG unsigned longs */
	sigset_t set;
	unsigned long prevsp;

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

	set.sig[0] = sigctx.oldmask;
#if _NSIG_WORDS > 1
	set.sig[1] = sigctx._unused[3];
#endif
	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sigmask_lock);
	current->blocked = set;
	recalc_sigpending(current);
	spin_unlock_irq(&current->sigmask_lock);

	sc++;			/* Look at next sigcontext */
	if (sc == (struct sigcontext_struct *)(sigctx.regs)) {
		/* Last stacked signal - restore registers */
		sr = (struct sigregs *) sigctx.regs;
		if (regs->msr & MSR_FP )
			giveup_fpu(current);
		if (copy_from_user(saved_regs, &sr->gp_regs,
				   sizeof(sr->gp_regs)))
			goto badframe;
		saved_regs[PT_MSR] = (regs->msr & ~MSR_USERCHANGE)
			| (saved_regs[PT_MSR] & MSR_USERCHANGE);
		saved_regs[PT_SOFTE] = regs->softe;
		memcpy(regs, saved_regs, GP_REGS_SIZE);

		if (copy_from_user(current->thread.fpr, &sr->fp_regs,
				   sizeof(sr->fp_regs)))
			goto badframe;

		ret = regs->result;

	} else {
		/* More signals to go */
		regs->gpr[1] = (unsigned long)sc - __SIGNAL_FRAMESIZE;
		if (copy_from_user(&sigctx, sc, sizeof(sigctx)))
			goto badframe;
		sr = (struct sigregs *) sigctx.regs;
		regs->gpr[3] = ret = sigctx.signal;
		regs->gpr[4] = (unsigned long) sc;
		regs->link = (unsigned long) &sr->tramp;
		regs->nip = sigctx.handler;

		if (get_user(prevsp, &sr->gp_regs[PT_R1])
		    || put_user(prevsp, (unsigned long *) regs->gpr[1]))
			goto badframe;
	}
	return ret;

badframe:
	do_exit(SIGSEGV);
}	

/*
 * Set up a signal frame.
 */
static void
setup_frame(struct pt_regs *regs, struct sigregs *frame,
            unsigned long newsp)
{

	/* Handler is *really* a pointer to the function descriptor for
	 * the signal routine.  The first entry in the function
	 * descriptor is the entry address of signal and the second
	 * entry is the TOC value we need to use.
	 */
	struct funct_descr_entry {
		unsigned long entry;
		unsigned long toc;
	};
  
	struct funct_descr_entry * funct_desc_ptr;
	unsigned long temp_ptr;

	struct sigcontext_struct *sc = (struct sigcontext_struct *) newsp;
  
	if (verify_area(VERIFY_WRITE, frame, sizeof(*frame)))
		goto badframe;
	if (regs->msr & MSR_FP)
		giveup_fpu(current);
	if (__copy_to_user(&frame->gp_regs, regs, GP_REGS_SIZE)
	    || __copy_to_user(&frame->fp_regs, current->thread.fpr,
			      ELF_NFPREG * sizeof(double))
	    || __put_user(0x38000000UL + __NR_sigreturn, &frame->tramp[0])    /* li r0, __NR_sigreturn */
	    || __put_user(0x44000002UL, &frame->tramp[1]))   /* sc */
		goto badframe;
	flush_icache_range((unsigned long) &frame->tramp[0],
			   (unsigned long) &frame->tramp[2]);

	newsp -= __SIGNAL_FRAMESIZE;
	if ( get_user(temp_ptr, &sc->handler))
		goto badframe;
  
	funct_desc_ptr = ( struct funct_descr_entry *) temp_ptr;

	if (put_user(regs->gpr[1], (unsigned long *)newsp)
	    || get_user(regs->nip, & funct_desc_ptr ->entry)
	    || get_user(regs->gpr[2],& funct_desc_ptr->toc)
	    || get_user(regs->gpr[3], &sc->signal))
		goto badframe;
	regs->gpr[1] = newsp;
	regs->gpr[4] = (unsigned long) sc;
	regs->link = (unsigned long) frame->tramp;


	PPCDBG(PPCDBG_SIGNAL, "setup_frame - returning - regs->gpr[1]=%lx, regs->gpr[4]=%lx, regs->link=%lx \n",
	       regs->gpr[1], regs->gpr[4], regs->link);

	return;

 badframe:
	PPCDBG(PPCDBG_SIGNAL, "setup_frame - badframe in setup_frame, regs=%p frame=%p newsp=%lx\n", regs, frame, newsp);  PPCDBG_ENTER_DEBUGGER();
#if DEBUG_SIG
	printk("badframe in setup_frame, regs=%p frame=%p newsp=%lx\n",
	       regs, frame, newsp);
#endif
	do_exit(SIGSEGV);
}

/*
 * 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 *newspp, unsigned long frame)
{
	struct sigcontext_struct *sc;
        struct rt_sigframe *rt_sf;

	if (regs->trap == 0x0C00 /* System Call! */
	    && ((int)regs->result == -ERESTARTNOHAND ||
		((int)regs->result == -ERESTARTSYS &&
		 !(ka->sa.sa_flags & SA_RESTART))))
		regs->result = -EINTR;
        /* Set up Signal Frame */
     
	if (ka->sa.sa_flags & SA_SIGINFO) {
		/* Put a Real Time Context onto stack */
		*newspp -= sizeof(*rt_sf);
		rt_sf = (struct rt_sigframe *) *newspp;
		if (verify_area(VERIFY_WRITE, rt_sf, sizeof(*rt_sf)))
			goto badframe;
                

		if (__put_user((unsigned long) ka->sa.sa_handler, &rt_sf->uc.uc_mcontext.handler)
		    || __put_user(&rt_sf->info, &rt_sf->pinfo)
		    || __put_user(&rt_sf->uc, &rt_sf->puc)
		    /* Put the siginfo */
		    || __copy_to_user(&rt_sf->info, info, sizeof(*info))
		    /* Create the ucontext */
		    || __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)
		    || __copy_to_user(&rt_sf->uc.uc_sigmask, oldset, sizeof(*oldset))
		    /* mcontext.regs points to preamble register frame */
		    || __put_user((struct pt_regs *)frame, &rt_sf->uc.uc_mcontext.regs)
		    || __put_user(sig, &rt_sf->uc.uc_mcontext.signal))
			goto badframe;
               
	} else {
	        /* Put another sigcontext on the stack */
                *newspp -= sizeof(*sc);
        	sc = (struct sigcontext_struct *) *newspp;
        	if (verify_area(VERIFY_WRITE, sc, sizeof(*sc)))
	        	goto badframe;

        	if (__put_user((unsigned long) ka->sa.sa_handler, &sc->handler)
	           || __put_user(oldset->sig[0], &sc->oldmask)
#if _NSIG_WORDS > 1
	           || __put_user(oldset->sig[1], &sc->_unused[3])
#endif
	           || __put_user((struct pt_regs *)frame, &sc->regs)
	           || __put_user(sig, &sc->signal))
	        	goto badframe;
	}

	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);
	}
	return;

badframe:
#if DEBUG_SIG
	printk("badframe in handle_signal, regs=%p frame=%lx newsp=%lx\n",
	       regs, frame, *newspp);
	printk("sc=%p sig=%d ka=%p info=%p oldset=%p\n", sc, sig, ka, info, oldset);
#endif
	do_exit(SIGSEGV);
}

/*
 * 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.
 */
extern int do_signal32(sigset_t *oldset, struct pt_regs *regs);
int do_signal(sigset_t *oldset, struct pt_regs *regs)
{
	siginfo_t info;
	struct k_sigaction *ka;
	unsigned long frame, newsp;

	/*
	 * If the current thread is 32 bit - invoke the
	 * 32 bit signal handling code
	 */
	if (current->thread.flags & PPC_FLAG_32BIT)
		return do_signal32(oldset, regs);

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

	newsp = frame = 0;

	for (;;) {
		unsigned long signr;

                PPCDBG(PPCDBG_SIGNAL, "do_signal - (pre) dequeueing signal - pid=%ld current=%lx comm=%s \n", current->pid, current, current->comm);
		spin_lock_irq(&current->sigmask_lock);
		signr = dequeue_signal(&current->blocked, &info);
		spin_unlock_irq(&current->sigmask_lock);
                PPCDBG(PPCDBG_SIGNAL, "do_signal - (aft) dequeueing signal - signal=%lx - pid=%ld current=%lx comm=%s \n", signr, current->pid, current, current->comm);

		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];

  
                PPCDBG(PPCDBG_SIGNAL, "do_signal - ka=%p, action handler=%lx \n", ka, ka->sa.sa_handler);

		if (ka->sa.sa_handler == SIG_IGN) {
                        PPCDBG(PPCDBG_SIGNAL, "do_signal - into SIG_IGN logic \n");
			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;
                        PPCDBG(PPCDBG_SIGNAL, "do_signal - into SIG_DFL logic \n");

			/* 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: {
				struct signal_struct *sig;
				current->state = TASK_STOPPED;
				current->exit_code = signr;
				sig = current->p_pptr->sig;
				if (sig && !(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 ( (ka->sa.sa_flags & SA_ONSTACK)
		     && (! on_sig_stack(regs->gpr[1])))
			newsp = (current->sas_ss_sp + current->sas_ss_size);
		else
			newsp = regs->gpr[1];
		newsp = frame = newsp - sizeof(struct sigregs);

		/* Whee!  Actually deliver the signal.  */
  
                PPCDBG(PPCDBG_SIGNAL, "do_signal - GOING TO RUN SIGNAL HANDLER - pid=%ld current=%lx comm=%s \n", current->pid, current, current->comm);
		handle_signal(signr, ka, &info, oldset, regs, &newsp, frame);
                PPCDBG(PPCDBG_SIGNAL, "do_signal - after running signal handler - pid=%ld current=%lx comm=%s \n", current->pid, current, current->comm);
                break;
	}

	if (regs->trap == 0x0C00 /* System Call! */ &&
	    ((int)regs->result == -ERESTARTNOHAND ||
	     (int)regs->result == -ERESTARTSYS ||
	     (int)regs->result == -ERESTARTNOINTR)) {
                PPCDBG(PPCDBG_SIGNAL, "do_signal - going to back up & retry system call \n");
		regs->gpr[3] = regs->orig_gpr3;
		regs->nip -= 4;		/* Back up & retry system call */
		regs->result = 0;
	}

	if (newsp == frame)
          {
             PPCDBG(PPCDBG_SIGNAL, "do_signal - returning w/ no signal delivered \n");
             return 0;		/* no signals delivered */
           }
  
     

        if (ka->sa.sa_flags & SA_SIGINFO)
             setup_rt_frame(regs, (struct sigregs *) frame, newsp);
        else        
	    setup_frame(regs, (struct sigregs *) frame, newsp);
        PPCDBG(PPCDBG_SIGNAL, "do_signal - returning a signal was delivered \n");
	return 1;
}