signal_32.c

linux 内核源代码

	/* enter the signal handler in big-endian mode */
	regs->msr &= ~MSR_LE;
	regs->trap = 0;
	return 1;

badframe:
#ifdef DEBUG_SIG
	printk("badframe in handle_rt_signal, regs=%p frame=%p newsp=%lx\n",
	       regs, frame, newsp);
#endif
	if (show_unhandled_signals && printk_ratelimit())
		printk(KERN_INFO "%s[%d]: bad frame in handle_rt_signal32: "
			"%p nip %08lx lr %08lx\n",
			current->comm, current->pid,
			addr, regs->nip, regs->link);

	force_sigsegv(sig, current);
	return 0;
}

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

	if (get_sigset_t(&set, &ucp->uc_sigmask))
		return -EFAULT;
#ifdef CONFIG_PPC64
	{
		u32 cmcp;

		if (__get_user(cmcp, &ucp->uc_regs))
			return -EFAULT;
		mcp = (struct mcontext __user *)(u64)cmcp;
		/* no need to check access_ok(mcp), since mcp < 4GB */
	}
#else
	if (__get_user(mcp, &ucp->uc_regs))
		return -EFAULT;
	if (!access_ok(VERIFY_READ, mcp, sizeof(*mcp)))
		return -EFAULT;
#endif
	restore_sigmask(&set);
	if (restore_user_regs(regs, mcp, sig))
		return -EFAULT;

	return 0;
}

long 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) {
		struct mcontext __user *mctx;

		/*
		 * old_ctx might not be 16-byte aligned, in which
		 * case old_ctx->uc_mcontext won't be either.
		 * Because we have the old_ctx->uc_pad2 field
		 * before old_ctx->uc_mcontext, we need to round down
		 * from &old_ctx->uc_mcontext to a 16-byte boundary.
		 */
		mctx = (struct mcontext __user *)
			((unsigned long) &old_ctx->uc_mcontext & ~0xfUL);
		if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx))
		    || save_user_regs(regs, mctx, 0)
		    || put_sigset_t(&old_ctx->uc_sigmask, &current->blocked)
		    || __put_user(to_user_ptr(mctx), &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);

	set_thread_flag(TIF_RESTOREALL);
	return 0;
}

long 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(*rt_sf)))
		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
	 */
#ifdef CONFIG_PPC64
	/*
	 * We use the compat_sys_ version that does the 32/64 bits conversion
	 * and takes userland pointer directly. What about error checking ?
	 * nobody does any...
	 */
	compat_sys_sigaltstack((u32)(u64)&rt_sf->uc.uc_stack, 0, 0, 0, 0, 0, regs);
#else
	do_sigaltstack(&rt_sf->uc.uc_stack, NULL, regs->gpr[1]);
#endif
	set_thread_flag(TIF_RESTOREALL);
	return 0;

 bad:
	if (show_unhandled_signals && printk_ratelimit())
		printk(KERN_INFO "%s[%d]: bad frame in sys_rt_sigreturn: "
			"%p nip %08lx lr %08lx\n",
			current->comm, current->pid,
			rt_sf, regs->nip, regs->link);

	force_sig(SIGSEGV, current);
	return 0;
}

#ifdef CONFIG_PPC32
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 char tmp;
	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 + i, 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 (!access_ok(VERIFY_READ, ctx, sizeof(*ctx))
	    || __get_user(tmp, (u8 __user *) ctx)
	    || __get_user(tmp, (u8 __user *) (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(ctx, regs, 1)) {
		if (show_unhandled_signals && printk_ratelimit())
			printk(KERN_INFO "%s[%d]: bad frame in "
				"sys_debug_setcontext: %p nip %08lx "
				"lr %08lx\n",
				current->comm, current->pid,
				ctx, regs->nip, regs->link);

		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]);

	set_thread_flag(TIF_RESTOREALL);
 out:
	return 0;
}
#endif

/*
 * OK, we're invoking a handler
 */
int handle_signal32(unsigned long sig, struct k_sigaction *ka,
		    siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
{
	struct sigcontext __user *sc;
	struct sigframe __user *frame;
	unsigned long newsp = 0;

	/* Set up Signal Frame */
	frame = get_sigframe(ka, regs, sizeof(*frame));
	if (unlikely(frame == NULL))
		goto badframe;
	sc = (struct sigcontext __user *) &frame->sctx;

#if _NSIG != 64
#error "Please adjust handle_signal()"
#endif
	if (__put_user(to_user_ptr(ka->sa.sa_handler), &sc->handler)
	    || __put_user(oldset->sig[0], &sc->oldmask)
#ifdef CONFIG_PPC64
	    || __put_user((oldset->sig[0] >> 32), &sc->_unused[3])
#else
	    || __put_user(oldset->sig[1], &sc->_unused[3])
#endif
	    || __put_user(to_user_ptr(&frame->mctx), &sc->regs)
	    || __put_user(sig, &sc->signal))
		goto badframe;

	if (vdso32_sigtramp && current->mm->context.vdso_base) {
		if (save_user_regs(regs, &frame->mctx, 0))
			goto badframe;
		regs->link = current->mm->context.vdso_base + vdso32_sigtramp;
	} else {
		if (save_user_regs(regs, &frame->mctx, __NR_sigreturn))
			goto badframe;
		regs->link = (unsigned long) frame->mctx.tramp;
	}

	current->thread.fpscr.val = 0;	/* turn off all fp exceptions */

	/* create a stack frame for the caller of the handler */
	newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE;
	if (put_user(regs->gpr[1], (u32 __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;
	/* enter the signal handler in big-endian mode */
	regs->msr &= ~MSR_LE;
	regs->trap = 0;

	return 1;

badframe:
#ifdef DEBUG_SIG
	printk("badframe in handle_signal, regs=%p frame=%p newsp=%lx\n",
	       regs, frame, newsp);
#endif
	if (show_unhandled_signals && printk_ratelimit())
		printk(KERN_INFO "%s[%d]: bad frame in handle_signal32: "
			"%p nip %08lx lr %08lx\n",
			current->comm, current->pid,
			frame, regs->nip, regs->link);

	force_sigsegv(sig, current);
	return 0;
}

/*
 * Do a signal return; undo the signal stack.
 */
long 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;
	void __user *addr;
	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);
	addr = sc;
	if (copy_from_user(&sigctx, sc, sizeof(sigctx)))
		goto badframe;

#ifdef CONFIG_PPC64
	/*
	 * Note that PPC32 puts the upper 32 bits of the sigmask in the
	 * unused part of the signal stackframe
	 */
	set.sig[0] = sigctx.oldmask + ((long)(sigctx._unused[3]) << 32);
#else
	set.sig[0] = sigctx.oldmask;
	set.sig[1] = sigctx._unused[3];
#endif
	restore_sigmask(&set);

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

	set_thread_flag(TIF_RESTOREALL);
	return 0;

badframe:
	if (show_unhandled_signals && printk_ratelimit())
		printk(KERN_INFO "%s[%d]: bad frame in sys_sigreturn: "
			"%p nip %08lx lr %08lx\n",
			current->comm, current->pid,
			addr, regs->nip, regs->link);

	force_sig(SIGSEGV, current);
	return 0;
}