signal.c

来自「底层驱动开发」· C语言 代码 · 共 772 行 · 第 1/2 页

	    || __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
	force_sigsegv(sig, 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 (!access_ok(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 (!access_ok(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 access_ok
	 * 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 (!access_ok(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;
}

int sys_debug_setcontext(struct ucontext __user *ctx,
			 int ndbg, struct sig_dbg_op __user *dbg,
			 int r6, int r7, int r8,
			 struct pt_regs *regs)
{
	struct sig_dbg_op op;
	int i;
	unsigned long new_msr = regs->msr;
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
	unsigned long new_dbcr0 = current->thread.dbcr0;
#endif

	for (i=0; i<ndbg; i++) {
		if (__copy_from_user(&op, dbg, sizeof(op)))
			return -EFAULT;
		switch (op.dbg_type) {
		case SIG_DBG_SINGLE_STEPPING:
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
			if (op.dbg_value) {
				new_msr |= MSR_DE;
				new_dbcr0 |= (DBCR0_IDM | DBCR0_IC);
			} else {
				new_msr &= ~MSR_DE;
				new_dbcr0 &= ~(DBCR0_IDM | DBCR0_IC);
			}
#else
			if (op.dbg_value)
				new_msr |= MSR_SE;
			else
				new_msr &= ~MSR_SE;
#endif
			break;
		case SIG_DBG_BRANCH_TRACING:
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
			return -EINVAL;
#else
			if (op.dbg_value)
				new_msr |= MSR_BE;
			else
				new_msr &= ~MSR_BE;
#endif
			break;

		default:
			return -EINVAL;
		}
	}

	/* We wait until here to actually install the values in the
	   registers so if we fail in the above loop, it will not
	   affect the contents of these registers.  After this point,
	   failure is a problem, anyway, and it's very unlikely unless
	   the user is really doing something wrong. */
	regs->msr = new_msr;
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
	current->thread.dbcr0 = new_dbcr0;
#endif

	/*
	 * 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 access_ok
	 * 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(ctx, regs, 1)) {
		force_sig(SIGSEGV, current);
		goto out;
	}

	/*
	 * 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(&ctx->uc_stack, NULL, regs->gpr[1]);

	sigreturn_exit(regs);
	/* doesn't actually return back to here */

 out:
	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 (!access_ok(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 __user *)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
	force_sigsegv(sig, 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 (!access_ok(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 (try_to_freeze()) {
		signr = 0;
		if (!signal_pending(current))
			goto no_signal;
	}

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

	newsp = frame = 0;

	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 no_signal:
	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);

	spin_lock_irq(&current->sighand->siglock);
	sigorsets(&current->blocked,&current->blocked,&ka.sa.sa_mask);
	if (!(ka.sa.sa_flags & SA_NODEFER))
		sigaddset(&current->blocked, signr);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	return 1;
}