signal.c

linux-2.6.15.6

		panic ("Double exception sys_sigreturn\n");

	if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;

	if (__get_user(set.sig[0], &frame->sc.oldmask)
	    || (_NSIG_WORDS > 1
		&& __copy_from_user(&set.sig[1], &frame->extramask,
				    sizeof(frame->extramask))))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);

	spin_lock_irq(&current->sighand->siglock);
	current->blocked = set;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigcontext(regs, &frame->sc))
		goto badframe;
	return regs->areg[2];

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

asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
{
	struct rt_sigframe *frame = (struct rt_sigframe *)regs->areg[1];
	sigset_t set;
	stack_t st;
	int ret;
	if (regs->depc > 64)
	{
		printk("!!!!!!! DEPC !!!!!!!\n");
		return 0;
	}

	if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;

	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);
	current->blocked = set;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
		goto badframe;
	ret = regs->areg[2];

	if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
		goto badframe;
	/* It is more difficult to avoid calling this function than to
	   call it and ignore errors.  */
	do_sigaltstack(&st, NULL, regs->areg[1]);

	return ret;

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

/*
 * Set up a signal frame.
 */

/*
 * Determine which stack to use..
 */
static inline void *
get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
{
	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
		sp = current->sas_ss_sp + current->sas_ss_size;

	return (void *)((sp - frame_size) & -16ul);
}

#define USE_SIGRETURN		0
#define USE_RT_SIGRETURN	1

static int
gen_return_code(unsigned char *codemem, unsigned int use_rt_sigreturn)
{
	unsigned int retcall;
	int err = 0;

#if 0
	/* Ignoring SA_RESTORER for now; it's supposed to be obsolete,
	 * and the xtensa glibc doesn't use it.
	 */
	if (ka->sa.sa_flags & SA_RESTORER) {
		regs->pr = (unsigned long) ka->sa.sa_restorer;
	} else
#endif /* 0 */
	{

#if (__NR_sigreturn > 255) || (__NR_rt_sigreturn > 255)

/* The 12-bit immediate is really split up within the 24-bit MOVI
 * instruction.  As long as the above system call numbers fit within
 * 8-bits, the following code works fine. See the Xtensa ISA for
 * details.
 */

#error Generating the MOVI instruction below breaks!
#endif

		retcall = use_rt_sigreturn ? __NR_rt_sigreturn : __NR_sigreturn;

#ifdef __XTENSA_EB__   /* Big Endian version */
		/* Generate instruction:  MOVI a2, retcall */
		err |= __put_user(0x22, &codemem[0]);
		err |= __put_user(0x0a, &codemem[1]);
		err |= __put_user(retcall, &codemem[2]);
		/* Generate instruction:  SYSCALL */
		err |= __put_user(0x00, &codemem[3]);
		err |= __put_user(0x05, &codemem[4]);
		err |= __put_user(0x00, &codemem[5]);

#elif defined __XTENSA_EL__   /* Little Endian version */
		/* Generate instruction:  MOVI a2, retcall */
		err |= __put_user(0x22, &codemem[0]);
		err |= __put_user(0xa0, &codemem[1]);
		err |= __put_user(retcall, &codemem[2]);
		/* Generate instruction:  SYSCALL */
		err |= __put_user(0x00, &codemem[3]);
		err |= __put_user(0x50, &codemem[4]);
		err |= __put_user(0x00, &codemem[5]);
#else
#error Must use compiler for Xtensa processors.
#endif
	}

	/* Flush generated code out of the data cache */

	if (err == 0)
		__flush_invalidate_cache_range((unsigned long)codemem, 6UL);

	return err;
}

static void
set_thread_state(struct pt_regs *regs, void *stack, unsigned char *retaddr,
	void *handler, unsigned long arg1, void *arg2, void *arg3)
{
	/* Set up registers for signal handler */
	start_thread(regs, (unsigned long) handler, (unsigned long) stack);

	/* Set up a stack frame for a call4
	 * Note: PS.CALLINC is set to one by start_thread
	 */
	regs->areg[4] = (((unsigned long) retaddr) & 0x3fffffff) | 0x40000000;
	regs->areg[6] = arg1;
	regs->areg[7] = (unsigned long) arg2;
	regs->areg[8] = (unsigned long) arg3;
}

static void setup_frame(int sig, struct k_sigaction *ka,
			sigset_t *set, struct pt_regs *regs)
{
	struct sigframe *frame;
	int err = 0;
	int signal;

	frame = get_sigframe(ka, regs->areg[1], sizeof(*frame));
	if (regs->depc > 64)
	{
		printk("!!!!!!! DEPC !!!!!!!\n");
		return;
	}


	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;

	signal = current_thread_info()->exec_domain
		&& current_thread_info()->exec_domain->signal_invmap
		&& sig < 32
		? current_thread_info()->exec_domain->signal_invmap[sig]
		: sig;

	err |= setup_sigcontext(&frame->sc, &frame->cpstate, regs, set->sig[0]);

	if (_NSIG_WORDS > 1) {
		err |= __copy_to_user(frame->extramask, &set->sig[1],
				      sizeof(frame->extramask));
	}

	/* Create sys_sigreturn syscall in stack frame */
	err |= gen_return_code(frame->retcode, USE_SIGRETURN);

	if (err)
		goto give_sigsegv;

	/* Create signal handler execution context.
	 * Return context not modified until this point.
	 */
	set_thread_state(regs, frame, frame->retcode,
		ka->sa.sa_handler, signal, &frame->sc, NULL);

	/* Set access mode to USER_DS.  Nomenclature is outdated, but
	 * functionality is used in uaccess.h
	 */
	set_fs(USER_DS);


#if DEBUG_SIG
	printk("SIG deliver (%s:%d): signal=%d sp=%p pc=%08x\n",
		current->comm, current->pid, signal, frame, regs->pc);
#endif

	return;

give_sigsegv:
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	force_sig(SIGSEGV, current);
}

static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
			   sigset_t *set, struct pt_regs *regs)
{
	struct rt_sigframe *frame;
	int err = 0;
	int signal;

	frame = get_sigframe(ka, regs->areg[1], sizeof(*frame));
	if (regs->depc > 64)
		panic ("Double exception sys_sigreturn\n");

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;

	signal = current_thread_info()->exec_domain
		&& current_thread_info()->exec_domain->signal_invmap
		&& sig < 32
		? current_thread_info()->exec_domain->signal_invmap[sig]
		: sig;

	err |= copy_siginfo_to_user(&frame->info, info);

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(0, &frame->uc.uc_link);
	err |= __put_user((void *)current->sas_ss_sp,
			  &frame->uc.uc_stack.ss_sp);
	err |= __put_user(sas_ss_flags(regs->areg[1]),
			  &frame->uc.uc_stack.ss_flags);
	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
	err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->cpstate,
			        regs, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	/* Create sys_rt_sigreturn syscall in stack frame */
	err |= gen_return_code(frame->retcode, USE_RT_SIGRETURN);

	if (err)
		goto give_sigsegv;

	/* Create signal handler execution context.
	 * Return context not modified until this point.
	 */
	set_thread_state(regs, frame, frame->retcode,
		ka->sa.sa_handler, signal, &frame->info, &frame->uc);

	/* Set access mode to USER_DS.  Nomenclature is outdated, but
	 * functionality is used in uaccess.h
	 */
	set_fs(USER_DS);

#if DEBUG_SIG
	printk("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08x\n",
		current->comm, current->pid, signal, frame, regs->pc);
#endif

	return;

give_sigsegv:
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	force_sig(SIGSEGV, current);
}



/*
 * 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.
 */
int do_signal(struct pt_regs *regs, sigset_t *oldset)
{
	siginfo_t info;
	int signr;
	struct k_sigaction ka;

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

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

	/* Are we from a system call? */
	if (regs->syscall >= 0) {
		/* If so, check system call restarting.. */
		switch (regs->areg[2]) {
			case ERESTARTNOHAND:
			case ERESTART_RESTARTBLOCK:
				regs->areg[2] = -EINTR;
				break;

			case ERESTARTSYS:
				if (!(ka.sa.sa_flags & SA_RESTART)) {
					regs->areg[2] = -EINTR;
					break;
				}
			/* fallthrough */
			case ERESTARTNOINTR:
				regs->areg[2] = regs->syscall;
				regs->pc -= 3;
		}
	}

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

	/* Whee!  Actually deliver the signal.  */

	/* Set up the stack frame */
	if (ka.sa.sa_flags & SA_SIGINFO)
		setup_rt_frame(signr, &ka, &info, oldset, regs);
	else
		setup_frame(signr, &ka, oldset, regs);

	if (ka.sa.sa_flags & SA_ONESHOT)
		ka.sa.sa_handler = SIG_DFL;

	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;
}