/*
 * Architecture-specific signal handling support.
 *
 * Copyright (C) 1999-2000 Hewlett-Packard Co
 * Copyright (C) 1999-2000 David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * Derived from i386 and Alpha versions.
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/wait.h>

#include <asm/ia32.h>
#include <asm/uaccess.h>
#include <asm/rse.h>
#include <asm/sigcontext.h>

#define DEBUG_SIG	0
#define STACK_ALIGN	16		/* minimal alignment for stack pointer */
#define _BLOCKABLE	(~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

#if _NSIG_WORDS > 1
# define PUT_SIGSET(k,u)	__copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
# define GET_SIGSET(k,u)	__copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
#else
# define PUT_SIGSET(k,u)	__put_user((k)->sig[0], &(u)->sig[0])
# define GET_SIGSET(k,u)	__get_user((k)->sig[0], &(u)->sig[0])
#endif

struct sigframe {
	struct siginfo info;
	struct sigcontext sc;
};

extern long sys_wait4 (int, int *, int, struct rusage *);
extern long ia64_do_signal (sigset_t *, struct pt_regs *, long);	/* forward decl */

long
ia64_rt_sigsuspend (sigset_t *uset, size_t sigsetsize, struct pt_regs *pt)
{
	sigset_t oldset, set;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;
	if (GET_SIGSET(&set, uset))
		return -EFAULT;

	sigdelsetmask(&set, ~_BLOCKABLE);

	spin_lock_irq(&current->sigmask_lock);
	{
		oldset = current->blocked;
		current->blocked = set;
		recalc_sigpending(current);
	}
	spin_unlock_irq(&current->sigmask_lock);

	/*
	 * The return below usually returns to the signal handler.  We need to
	 * pre-set the correct error code here to ensure that the right values
	 * get saved in sigcontext by ia64_do_signal.
	 */
	pt->r8 = EINTR;
	pt->r10 = -1;
	while (1) {
		set_current_state(TASK_INTERRUPTIBLE);
		schedule();
		if (ia64_do_signal(&oldset, pt, 1))
			return -EINTR;
	}
}

asmlinkage long
sys_sigaltstack (const stack_t *uss, stack_t *uoss, long arg2, long arg3, long arg4,
		 long arg5, long arg6, long arg7, long stack)
{
	struct pt_regs *pt = (struct pt_regs *) &stack;

	return do_sigaltstack(uss, uoss, pt->r12);
}

static long
restore_sigcontext (struct sigcontext *sc, struct pt_regs *pt)
{
	struct switch_stack *sw = (struct switch_stack *) pt - 1;
	unsigned long ip, flags, nat, um;
	long err;

	/* restore scratch that always needs gets updated during signal delivery: */
	err = __get_user(flags, &sc->sc_flags);

	err |= __get_user(nat, &sc->sc_nat);
	err |= __get_user(ip, &sc->sc_ip);			/* instruction pointer */
	err |= __get_user(pt->ar_fpsr, &sc->sc_ar_fpsr);
	err |= __get_user(pt->ar_pfs, &sc->sc_ar_pfs);
	err |= __get_user(um, &sc->sc_um);			/* user mask */
	err |= __get_user(pt->ar_rsc, &sc->sc_ar_rsc);
	err |= __get_user(pt->ar_ccv, &sc->sc_ar_ccv);
	err |= __get_user(pt->ar_unat, &sc->sc_ar_unat);
	err |= __get_user(pt->pr, &sc->sc_pr);			/* predicates */
	err |= __get_user(pt->b0, &sc->sc_br[0]);		/* b0 (rp) */
	err |= __get_user(pt->b6, &sc->sc_br[6]);
	err |= __copy_from_user(&pt->r1, &sc->sc_gr[1], 3*8);	/* r1-r3 */
	err |= __copy_from_user(&pt->r8, &sc->sc_gr[8], 4*8);	/* r8-r11 */
	err |= __copy_from_user(&pt->r12, &sc->sc_gr[12], 4*8);	/* r12-r15 */
	err |= __copy_from_user(&pt->r16, &sc->sc_gr[16], 16*8);	/* r16-r31 */

	/* establish new instruction pointer: */
	pt->cr_iip = ip & ~0x3UL;
	ia64_psr(pt)->ri = ip & 0x3;
	pt->cr_ipsr = (pt->cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);

	ia64_put_nat_bits (pt, sw, nat);	/* restore the original scratch NaT bits */

	if (flags & IA64_SC_FLAG_FPH_VALID) {
		struct task_struct *fpu_owner = ia64_get_fpu_owner();

		__copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
		if (fpu_owner == current) {
			__ia64_load_fpu(current->thread.fph);
		}
	}
	return err;
}

/*
 * When we get here, ((struct switch_stack *) pt - 1) is a
 * switch_stack frame that has no defined value.  Upon return, we
 * expect sw->caller_unat to contain the new unat value.  The reason
 * we use a full switch_stack frame is so everything is symmetric
 * with ia64_do_signal().
 */
long
ia64_rt_sigreturn (struct pt_regs *pt)
{
	extern char ia64_strace_leave_kernel, ia64_leave_kernel;
	struct sigcontext *sc;
	struct siginfo si;
	sigset_t set;
	long retval;

	sc = &((struct sigframe *) (pt->r12 + 16))->sc;

	/*
	 * When we return to the previously executing context, r8 and
	 * r10 have already been setup the way we want them.  Indeed,
	 * if the signal wasn't delivered while in a system call, we
	 * must not touch r8 or r10 as otherwise user-level stat could
	 * be corrupted.
	 */
	retval = (long) &ia64_leave_kernel | 1;
	if ((current->flags & PF_TRACESYS)
	    && (sc->sc_flags & IA64_SC_FLAG_IN_SYSCALL))
		retval = (long) &ia64_strace_leave_kernel;

	if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
		goto give_sigsegv;

	if (GET_SIGSET(&set, &sc->sc_mask))
		goto give_sigsegv;

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

	if (restore_sigcontext(sc, pt))
		goto give_sigsegv;

#if DEBUG_SIG
	printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
	       current->comm, current->pid, pt->r12, pt->cr_iip);
#endif
	/*
	 * It is more difficult to avoid calling this function than to
	 * call it and ignore errors.
	 */
	do_sigaltstack(&sc->sc_stack, 0, pt->r12);
	return retval;

  give_sigsegv:
	si.si_signo = SIGSEGV;
	si.si_errno = 0;
	si.si_code = SI_KERNEL;
	si.si_pid = current->pid;
	si.si_uid = current->uid;
	si.si_addr = sc;
	force_sig_info(SIGSEGV, &si, current);
	return retval;
}

/*
 * This does just the minimum required setup of sigcontext.
 * Specifically, it only installs data that is either not knowable at
 * the user-level or that gets modified before execution in the
 * trampoline starts.  Everything else is done at the user-level.
 */
static long
setup_sigcontext (struct sigcontext *sc, sigset_t *mask, struct pt_regs *pt)
{
	struct switch_stack *sw = (struct switch_stack *) pt - 1;
	struct task_struct *fpu_owner = ia64_get_fpu_owner();
	unsigned long flags = 0, ifs, nat;
	long err;

	ifs = pt->cr_ifs;

	if (on_sig_stack((unsigned long) sc))
		flags |= IA64_SC_FLAG_ONSTACK;
	if ((ifs & (1UL << 63)) == 0) {
		/* if cr_ifs isn't valid, we got here through a syscall */
		flags |= IA64_SC_FLAG_IN_SYSCALL;
	}
	if ((fpu_owner == current) || (current->thread.flags & IA64_THREAD_FPH_VALID)) {
		flags |= IA64_SC_FLAG_FPH_VALID;
		if (fpu_owner == current) {
			__ia64_save_fpu(current->thread.fph);
		}
		__copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
	}

	/*
	 * Note: sw->ar_unat is UNDEFINED unless the process is being
	 * PTRACED.  However, this is OK because the NaT bits of the
	 * preserved registers (r4-r7) are never being looked at by
	 * the signal handler (register r4-r7 are used instead).
	 */
	nat = ia64_get_nat_bits(pt, sw);

	err  = __put_user(flags, &sc->sc_flags);
	err |= __put_user(nat, &sc->sc_nat);
	err |= PUT_SIGSET(mask, &sc->sc_mask);
	err |= __put_user(pt->cr_ipsr & IA64_PSR_UM, &sc->sc_um);
	err |= __put_user(pt->ar_rsc, &sc->sc_ar_rsc);
	err |= __put_user(pt->ar_ccv, &sc->sc_ar_ccv);
	err |= __put_user(pt->ar_unat, &sc->sc_ar_unat);		/* ar.unat */
	err |= __put_user(pt->ar_fpsr, &sc->sc_ar_fpsr);		/* ar.fpsr */
	err |= __put_user(pt->ar_pfs, &sc->sc_ar_pfs);
	err |= __put_user(pt->pr, &sc->sc_pr);				/* predicates */
	err |= __put_user(pt->b0, &sc->sc_br[0]);			/* b0 (rp) */
	err |= __put_user(pt->b6, &sc->sc_br[6]);			/* b6 */
	err |= __put_user(pt->b7, &sc->sc_br[7]);			/* b7 */

	err |= __copy_to_user(&sc->sc_gr[1], &pt->r1, 3*8);		/* r1-r3 */
	err |= __copy_to_user(&sc->sc_gr[8], &pt->r8, 4*8);		/* r8-r11 */
	err |= __copy_to_user(&sc->sc_gr[12], &pt->r12, 4*8);	/* r12-r15 */
	err |= __copy_to_user(&sc->sc_gr[16], &pt->r16, 16*8);	/* r16-r31 */

	err |= __put_user(pt->cr_iip + ia64_psr(pt)->ri, &sc->sc_ip);
	err |= __put_user(pt->r12, &sc->sc_gr[12]);			/* r12 */
	return err;
}

static long
setup_frame (int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set, struct pt_regs *pt)
{
	struct switch_stack *sw = (struct switch_stack *) pt - 1;
	extern char ia64_sigtramp[], __start_gate_section[];
	unsigned long tramp_addr, new_rbs = 0;
	struct sigframe *frame;
	struct siginfo si;
	long err;

	frame = (void *) pt->r12;
	tramp_addr = GATE_ADDR + (ia64_sigtramp - __start_gate_section);
	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && !on_sig_stack((unsigned long) frame)) {
		new_rbs  = (current->sas_ss_sp + sizeof(long) - 1) & ~(sizeof(long) - 1);
		frame = (void *) ((current->sas_ss_sp + current->sas_ss_size)
				  & ~(STACK_ALIGN - 1));
	}
	frame = (void *) frame - ((sizeof(*frame) + STACK_ALIGN - 1) & ~(STACK_ALIGN - 1));

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

	err  = __copy_to_user(&frame->info, info, sizeof(siginfo_t));

	err |= __put_user(current->sas_ss_sp, &frame->sc.sc_stack.ss_sp);
	err |= __put_user(current->sas_ss_size, &frame->sc.sc_stack.ss_size);
	err |= __put_user(sas_ss_flags(pt->r12), &frame->sc.sc_stack.ss_flags);
	err |= setup_sigcontext(&frame->sc, set, pt);

	if (err)
		goto give_sigsegv;

	pt->r12 = (unsigned long) frame - 16;		/* new stack pointer */
	pt->r2  = sig;					/* signal number */
	pt->r3  = (unsigned long) ka->sa.sa_handler;	/* addr. of handler's proc. descriptor */
	pt->r15 = new_rbs;
	pt->ar_fpsr = FPSR_DEFAULT;			/* reset fpsr for signal handler */
	pt->cr_iip = tramp_addr;
	ia64_psr(pt)->ri = 0;				/* start executing in first slot */

	/*
	 * Note: this affects only the NaT bits of the scratch regs
	 * (the ones saved in pt_regs, which is exactly what we want.
	 * The NaT bits for the preserved regs (r4-r7) are in
	 * sw->ar_unat iff this process is being PTRACED.
	 */
	sw->caller_unat = 0;	/* ensure NaT bits of at least r2, r3, r12, and r15 are clear */

#if DEBUG_SIG
	printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%lx\n",
	       current->comm, current->pid, sig, pt->r12, pt->cr_iip, pt->r3);
#endif
	return 1;

  give_sigsegv:
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	si.si_signo = SIGSEGV;
	si.si_errno = 0;
	si.si_code = SI_KERNEL;
	si.si_pid = current->pid;
	si.si_uid = current->uid;
	si.si_addr = frame;
	force_sig_info(SIGSEGV, &si, current);
	return 0;
}

static long
handle_signal (unsigned long sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *oldset,
	       struct pt_regs *pt)
{
#ifdef CONFIG_IA32_SUPPORT
	if (IS_IA32_PROCESS(pt)) {
		/* send signal to IA-32 process */
		if (!ia32_setup_frame1(sig, ka, info, oldset, pt))
			return 0;
	} else
#endif
	/* send signal to IA-64 process */
	if (!setup_frame(sig, ka, info, oldset, pt))
		return 0;

	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 1;
}

/*
 * When we get here, `pt' points to struct pt_regs and ((struct
 * switch_stack *) pt - 1) points to a switch stack structure.
 * HOWEVER, in the normal case, the ONLY value valid in the
 * switch_stack is the caller_unat field.  The entire switch_stack is
 * valid ONLY if current->flags has PF_PTRACED set.
 *
 * 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.
 */
long
ia64_do_signal (sigset_t *oldset, struct pt_regs *pt, long in_syscall)
{
	struct k_sigaction *ka;
	siginfo_t info;
	long restart = in_syscall;

	/*
	 * In the ia64_leave_kernel code path, 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(pt))
		return 0;

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

	if (pt->r10 != -1) {
		/*
		 * A system calls has to be restarted only if one of
		 * the error codes ERESTARTNOHAND, ERESTARTSYS, or
		 * ERESTARTNOINTR is returned.  If r10 isn't -1 then
		 * r8 doesn't hold an error code and we don't need to
		 * restart the syscall, so we set in_syscall to zero.
		 */
		restart = 0;
	}

	for (;;) {
		unsigned long signr;

		spin_lock_irq(&current->sigmask_lock);
		signr = dequeue_signal(&current->blocked, &info);
		spin_unlock_irq(&current->sigmask_lock);

		if (!signr)
			break;

		if ((current->flags & PF_PTRACED) && signr != SIGKILL) {
			/* Let the debugger run.  */
			current->exit_code = signr;
			set_current_state(TASK_STOPPED);
			notify_parent(current, SIGCHLD);
			schedule();
			signr = current->exit_code;

			/* We're back.  Did the debugger cancel the sig?  */
			if (!signr)
				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];
		if (ka->sa.sa_handler == SIG_IGN) {
			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;

			/* Init gets no signals it doesn't want.  */
			if (current->pid == 1)
				continue;

			switch (signr) {
			      case SIGCONT: case SIGCHLD: case SIGWINCH:
				continue;

			      case SIGTSTP: case SIGTTIN: case SIGTTOU:
				if (is_orphaned_pgrp(current->pgrp))
					continue;
				/* FALLTHRU */

			      case SIGSTOP:
				set_current_state(TASK_STOPPED);
				current->exit_code = signr;
				if (!(current->p_pptr->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, pt))
					exit_code |= 0x80;
				/* FALLTHRU */

			      default:
				lock_kernel();
				sigaddset(&current->signal, signr);
				recalc_sigpending(current);
				current->flags |= PF_SIGNALED;
				do_exit(exit_code);
				/* NOTREACHED */
			}
		}

		if (restart) {
			switch (pt->r8) {
			      case ERESTARTSYS:
				if ((ka->sa.sa_flags & SA_RESTART) == 0) {
			      case ERESTARTNOHAND:
					pt->r8 = EINTR;
					/* note: pt->r10 is already -1 */
					break;
				}
			      case ERESTARTNOINTR:
				ia64_decrement_ip(pt);
			}
		}

		/* Whee!  Actually deliver the signal.  If the
		   delivery failed, we need to continue to iterate in
		   this loop so we can deliver the SIGSEGV... */
		if (handle_signal(signr, ka, &info, oldset, pt))
			return 1;
	}

	/* Did we come from a system call? */
	if (restart) {
		/* Restart the system call - no handlers present */
		if (pt->r8 == ERESTARTNOHAND ||
		    pt->r8 == ERESTARTSYS ||
		    pt->r8 == ERESTARTNOINTR) {
			/*
			 * Note: the syscall number is in r15 which is
			 * saved in pt_regs so all we need to do here
			 * is adjust ip so that the "break"
			 * instruction gets re-executed.
			 */
			ia64_decrement_ip(pt);
		}
	}
	return 0;
}