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/*
 *  linux/arch/or32/kernel/signal.c
 *
 *  or32 version
 *    author(s): Matjaz Breskvar (phoenix@bsemi.com)
 *
 *  derived from cris, i386, m68k, ppc, sh ports.
 *
 *  changes:
 *  18. 11. 2003: Matjaz Breskvar (phoenix@bsemi.com)
 *    initial port to or32 architecture
 *
 *  Based on linux/arch/cris/kernel/signal.c
 *    Copyright (C) 2000, 2001, 2002 Axis Communications AB
 *    Authors:  Bjorn Wesen (bjornw@axis.com)
 *
 */
 
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
 
#include <asm/processor.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/or32-hf.h>
 
#define DEBUG_SIG 0
 
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 
/* a syscall in Linux/OR32 is a "l.sys 1" instruction which is 4 bytes */
/* manipulate regs so that upon return, it will be re-executed */
 
/* We rely on that pc points to the instruction after "l.sys 1", so the
 * library must never do strange things like putting it in a delay slot.
 */
#define RESTART_OR32_SYS(regs) regs->gprs[1] = regs->orig_gpr3; regs->pc -= 4;
 
int do_signal(int canrestart, sigset_t *oldset, struct pt_regs *regs);
 
/*
 * Atomically swap in the new signal mask, and wait for a signal.  Define 
 * dummy arguments to be able to reach the regs argument.  (Note that this
 * arrangement relies on old_sigset_t occupying one register.)
 */
int sys_sigsuspend(old_sigset_t mask, long r4, long r5, long mof, 
		   long srp, struct pt_regs *regs)
{
	sigset_t saveset;
	phx_signal("mask 0x%lx, r4 0x%lx, r5 0x%lx, mof 0x%lx, srp 0x%lx, regs %p",
		   mask, r4, r5, mof, srp, regs);
 
 
	mask &= _BLOCKABLE;
	spin_lock_irq(&current->sighand->siglock);
	saveset = current->blocked;
	siginitset(&current->blocked, mask);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
 
	regs->gprs[1] = -EINTR;
	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(0, &saveset, regs))
			/* We will get here twice: once to call the signal
			   handler, then again to return from the
			   sigsuspend system call.  When calling the
			   signal handler, R10 holds the signal number as
			   set through do_signal.  The sigsuspend call
			   will return with the restored value set above;
			   always -EINTR.  */
			return regs->gprs[1];
	}
}
 
/* Define dummy arguments to be able to reach the regs argument.  (Note that
 * this arrangement relies on size_t occupying one register.)
 */
int sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize, long r5, 
		      long mof, long srp, struct pt_regs *regs)
{
	sigset_t saveset, newset;
 
	phx_signal("unewset %p, sigsetsize 0x%x, r5 0x%lx, mof 0x%lx, srp 0x%lx, regs %p",
		   unewset, sigsetsize, r5, mof, srp, regs);
 
	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;
 
	if (copy_from_user(&newset, unewset, sizeof(newset)))
		return -EFAULT;
	sigdelsetmask(&newset, ~_BLOCKABLE);
 
	spin_lock_irq(&current->sighand->siglock);
	saveset = current->blocked;
	current->blocked = newset;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
 
	regs->gprs[1] = -EINTR;
	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(0, &saveset, regs))
			/* We will get here twice: once to call the signal
			   handler, then again to return from the
			   sigsuspend system call.  When calling the
			   signal handler, R10 holds the signal number as
			   set through do_signal.  The sigsuspend call
			   will return with the restored value set above;
			   always -EINTR.  */
			return regs->gprs[1];
	}
}
 
int sys_sigaction(int sig, const struct old_sigaction *act,
		  struct old_sigaction *oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;
 
	phx_signal("sig %d, old act %p, old oact %p",
		   sig, act, oact);
 
	if (act) {
		old_sigset_t mask;
		if (verify_area(VERIFY_READ, act, sizeof(*act)) ||
		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
			return -EFAULT;
		__get_user(new_ka.sa.sa_flags, &act->sa_flags);
		__get_user(mask, &act->sa_mask);
		siginitset(&new_ka.sa.sa_mask, mask);
	}
 
	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 
	if (!ret && oact) {
		if (verify_area(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
			return -EFAULT;
		__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
		__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
	}
 
	return ret;
}
 
int sys_sigaltstack(const stack_t *uss, stack_t *uoss)
{
	struct pt_regs *regs = (struct pt_regs *) &uss;
	phx_signal("uss %p, uoss %p",
		   uss, uoss);
 
	return do_sigaltstack(uss, uoss, regs->sp);
}
 
 
/*
 * Do a signal return; undo the signal stack.
 */
 
struct sigframe {
	struct sigcontext sc;
	unsigned long extramask[_NSIG_WORDS-1];
	unsigned char retcode[16];  /* trampoline code */
};
 
struct rt_sigframe {
	struct siginfo *pinfo;
	void *puc;
	struct siginfo info;
	struct ucontext uc;
	unsigned char retcode[16];  /* trampoline code */
};
 
 
static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc)
{
	unsigned int err = 0;
	unsigned long old_usp;
 
	phx_signal("regs %p, sc %p",
		   regs, sc);
 
	/* restore the regs from &sc->regs (same as sc, since regs is first)
	 * (sc is already checked for VERIFY_READ since the sigframe was
	 *  checked in sys_sigreturn previously)
	 */
 
	if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
                goto badframe;
 
	/* make sure the U-flag is set so user-mode cannot fool us */
 
	regs->sr &= ~SPR_SR_SM;
//      __PHX__ FIXME	
//	regs->dccr |= 1 << 8;
 
	/* restore the old USP as it was before we stacked the sc etc.
	 * (we cannot just pop the sigcontext since we aligned the sp and
	 *  stuff after pushing it)
	 */
 
	err |= __get_user(old_usp, &sc->usp);
	phx_signal("old_usp 0x%lx", old_usp);
 
//      __PHX__ REALLY ???
//	wrusp(old_usp);
	regs->sp = old_usp;
 
	/* TODO: the other ports use regs->orig_XX to disable syscall checks
	 * after this completes, but we don't use that mechanism. maybe we can
	 * use it now ? 
	 */
 
	return err;
 
badframe:
	return 1;
}
 
/* Define dummy arguments to be able to reach the regs argument.  */
 
asmlinkage int sys_sigreturn(long r3, long r4, long r5, long mof, 
                             long srp, struct pt_regs *regs)
{
        struct sigframe *frame = (struct sigframe *)regs->sp;
        sigset_t set;
 
	phx_signal("r3 0x%lx, r4 0x%lx, r5 0x%lx, mof 0x%lx, srp 0x%lx, regs %p (regs->sp 0x%lx)",
		   r3, r4, r5, mof, srp, regs, regs->sp);
 
        /*
         * Since we stacked the signal on a dword boundary,
         * then frame should be dword aligned here.  If it's
         * not, then the user is trying to mess with us.
         */
        if (((long)frame) & 3)
                goto badframe;
 
	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();
 
	/* __PHX__ throw this out */
	phx_signal("SIGPENDING: %d", signal_pending(current));
 
	spin_unlock_irq(&current->sighand->siglock);
 
	if (restore_sigcontext(regs, &frame->sc))
		goto badframe;
 
	/* TODO: SIGTRAP when single-stepping as in arm ? */
 
	return regs->gprs[1];
 
badframe:
	force_sig(SIGSEGV, current);
	return 0;
}	
 
/* Define dummy arguments to be able to reach the regs argument.  */
 
asmlinkage int sys_rt_sigreturn(long r3, long r4, long r5, 
                                long mof, long srp, struct pt_regs *regs)
{
	struct rt_sigframe *frame = (struct rt_sigframe *)regs->sp;
	sigset_t set;
	stack_t st;
 
	phx_signal("r3 0x%lx, r4 0x%lx, r5 0x%lx, mof 0x%lx, srp 0x%lx, regs %p (regs->sp 0x%lx)",
		   r3, r4, r5, mof, srp, regs, regs->sp);
 
        /*
         * Since we stacked the signal on a dword boundary,
         * then frame should be dword aligned here.  If it's
         * not, then the user is trying to mess with us.
         */
        if (((long)frame) & 3)
                goto badframe;
 
	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;
 
	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->sp);
 
	return regs->gprs[1];
 
badframe:
	force_sig(SIGSEGV, current);
	return 0;
}	
 
/*
 * Set up a signal frame.
 */
 
static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
			    unsigned long mask)
{
	int err = 0;
	unsigned long usp = regs->sp;
 
	phx_signal("sc %p, regs %p, mask 0x%lx",
		   sc, regs, mask);
 
	/* copy the regs. they are first in sc so we can use sc directly */
 
	err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));
 
        /* Set the frametype to CRIS_FRAME_NORMAL for the execution of
           the signal handler. The frametype will be restored to its previous
           value in restore_sigcontext. */
	//        regs->frametype = CRIS_FRAME_NORMAL;
 
	/* then some other stuff */
 
	err |= __put_user(mask, &sc->oldmask);
 
	err |= __put_user(usp, &sc->usp);
 
	return err;
}
 
/* figure out where we want to put the new signal frame - usually on the stack */
 
static inline void * get_sigframe(struct k_sigaction *ka, 
				  struct pt_regs * regs, size_t frame_size)
{
	unsigned long sp = regs->sp;
 
	phx_signal("ka %p, regs %p, frame_size 0x%x (sp 0x%lx)",
		   ka, regs, frame_size, sp);
 
	/* This is the X/Open sanctioned signal stack switching.  */
	if (ka->sa.sa_flags & SA_ONSTACK) {
		if (! on_sig_stack(sp))
			sp = current->sas_ss_sp + current->sas_ss_size;
	}
 
	/* make sure the frame is dword-aligned */
 
	sp &= ~3;
 
	return (void *)(sp - frame_size);
}
 
/* grab and setup a signal frame.
 * 
 * basically we stack a lot of state info, and arrange for the
 * user-mode program to return to the kernel using either a
 * trampoline which performs the syscall sigreturn, or a provided
 * user-mode trampoline.
 */
 
static void setup_frame(int sig, struct k_sigaction *ka,
			sigset_t *set, struct pt_regs * regs)
{
	struct sigframe *frame;
	unsigned long return_ip;
	int err = 0;
 
	phx_signal("sig %d, ka %p, set %p, regs %p",
		   sig, ka, set, regs);
 
	frame = get_sigframe(ka, regs, sizeof(*frame));
 
	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;
 
	err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
	if (err)
		goto give_sigsegv;
 
	if (_NSIG_WORDS > 1) {
		err |= __copy_to_user(frame->extramask, &set->sig[1],
				      sizeof(frame->extramask));
	}
	if (err)
		goto give_sigsegv;
 
	/* Set up to return from userspace.  If provided, use a stub
	   already in userspace.  */
	if (ka->sa.sa_flags & SA_RESTORER) {
		return_ip = (unsigned long)ka->sa.sa_restorer;
		phx_signal("SA_RESTORER: return_ip 0x%lx", return_ip);
	} else {
		/* trampoline - the desired return ip is the retcode itself */
		return_ip = (unsigned long)&frame->retcode;
		phx_signal("ktrampoline: return_ip 0x%lx", return_ip);
		/* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */
		err |= __put_user(0xa960        , (short *)(frame->retcode+0));
		err |= __put_user(__NR_sigreturn, (short *)(frame->retcode+2));
		err |= __put_user(0x20000001, (unsigned long *)(frame->retcode+4));
		err |= __put_user(0x15000000, (unsigned long *)(frame->retcode+8));
	}
 
	if (err)
		goto give_sigsegv;
 
	/* Set up registers for signal handler */
 
	regs->pc = (unsigned long) ka->sa.sa_handler;       /* what we enter NOW   */
	regs->gprs[7] = return_ip;                          /* what we enter LATER */
	regs->gprs[1] = sig;                                /* first argument is signo */
 
	/* actually move the usp to reflect the stacked frame */
 
	//	wrusp((unsigned long)frame);
	regs->sp=(unsigned long) frame;
 
	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;
	unsigned long return_ip;
	int err = 0;
 
	phx_signal("sig %d, ka %p, info %p, set %p, regs %p",
		   sig, ka, info, set, regs);
 
	frame = get_sigframe(ka, regs, sizeof(*frame));
 
	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;
 
	err |= __put_user(&frame->info, &frame->pinfo);
	err |= __put_user(&frame->uc, &frame->puc);
	err |= copy_siginfo_to_user(&frame->info, info);
	if (err)
		goto give_sigsegv;
 
	/* Clear all the bits of the ucontext we don't use.  */
        err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 
	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
 
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 
	if (err)
		goto give_sigsegv;
 
	if (ka->sa.sa_flags & SA_RESTORER) {
		return_ip = (unsigned long)ka->sa.sa_restorer;
		phx_signal("SA_RESTORER: return_ip 0x%lx", return_ip);
	} else {
		/* trampoline - the desired return ip is the retcode itself */
		return_ip = (unsigned long)&frame->retcode;
		phx_signal("ktrampoline: return_ip 0x%lx", return_ip);
		/* This is l.ori r11,r0,__NR_sigreturn, l.sys 1 */
		err |= __put_user(0xa960        , (short *)(frame->retcode+0));
		err |= __put_user(__NR_sigreturn, (short *)(frame->retcode+2));
		err |= __put_user(0x20000001, (unsigned long *)(frame->retcode+4));
		err |= __put_user(0x15000000, (unsigned long *)(frame->retcode+8));
	}
 
	if (err)
		goto give_sigsegv;
 
	/* TODO what is the current->exec_domain stuff and invmap ? */
 
	/* Set up registers for signal handler */
 
	regs->pc = (unsigned long) ka->sa.sa_handler;  /* what we enter NOW   */
	regs->gprs[7] = return_ip;                          /* what we enter LATER */
	regs->gprs[1] = sig;                                /* first argument is signo */
        regs->gprs[3] = (unsigned long) &frame->info;       /* second argument is (siginfo_t *) */
        regs->gprs[4] = 0;                                  /* third argument is unused */
 
	/* actually move the usp to reflect the stacked frame */
 
	//	wrusp((unsigned long)frame);
	regs->sp = (unsigned long)frame;
 
	return;
 
give_sigsegv:
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	force_sig(SIGSEGV, current);
}
 
/*
 * OK, we're invoking a handler
 */	
 
extern inline void
handle_signal(int canrestart, unsigned long sig,
	      siginfo_t *info, struct k_sigaction *ka,
	      sigset_t *oldset, struct pt_regs * regs)
{
 
	phx_signal("canrestart %d, sig %ld, ka %p, info %p, oldset %p, regs %p",
		   canrestart, sig, ka, info, oldset, regs);
 
	phx_signal("(regs->pc 0x%lx, regs->sp 0x%lx, regs->gprs[7] 0x%lx)",
		   regs->pc, regs->sp, regs->gprs[7]);
 
	/* Are we from a system call? */
	if (canrestart) {
		/* If so, check system call restarting.. */
		switch (regs->gprs[1]) {
			case -ERESTARTNOHAND:
				/* ERESTARTNOHAND means that the syscall should only be
				   restarted if there was no handler for the signal, and since
				   we only get here if there is a handler, we dont restart */
				regs->gprs[1] = -EINTR;
				break;
 
			case -ERESTARTSYS:
				/* ERESTARTSYS means to restart the syscall if there is no
				   handler or the handler was registered with SA_RESTART */
				if (!(ka->sa.sa_flags & SA_RESTART)) {
					regs->gprs[1] = -EINTR;
					break;
				}
			/* fallthrough */
			case -ERESTARTNOINTR:
				/* ERESTARTNOINTR means that the syscall should be called again
				   after the signal handler returns. */
				RESTART_OR32_SYS(regs);
		}
	}
 
	/* Set up the stack frame */
	if (ka->sa.sa_flags & SA_SIGINFO)
		setup_rt_frame(sig, ka, info, oldset, regs);
	else
		setup_frame(sig, ka, oldset, regs);
 
	if (ka->sa.sa_flags & SA_ONESHOT)
		ka->sa.sa_handler = SIG_DFL;
 
	if (!(ka->sa.sa_flags & SA_NODEFER)) {
		spin_lock_irq(&current->sighand->siglock);
		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
		sigaddset(&current->blocked,sig);
		recalc_sigpending();
		spin_unlock_irq(&current->sighand->siglock);
	}
}
 
/*
 * 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.
 *
 * Also note that the regs structure given here as an argument, is the latest
 * pushed pt_regs. It may or may not be the same as the first pushed registers
 * when the initial usermode->kernelmode transition took place. Therefore
 * we can use user_mode(regs) to see if we came directly from kernel or user
 * mode below.
 */
 
int do_signal(int canrestart, sigset_t *oldset, struct pt_regs *regs)
{
	siginfo_t info;
	int signr;
	struct k_sigaction ka;
 
	check_stack(NULL, __FILE__, __FUNCTION__, __LINE__);
 
	phx_signal("canrestart %d, oldset %p, regs %p",
		   canrestart, oldset, regs);
 
	/*
	 * 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(regs))
		return 1;
 
	if (!oldset)
		oldset = &current->blocked;
 
	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
	if (signr > 0) {
		/* Whee!  Actually deliver the signal.  */
		handle_signal(canrestart, signr, &info, &ka, oldset, regs);
		return 1;
	}
 
	/* Did we come from a system call? */
	if (canrestart) {
		/* Restart the system call - no handlers present */
		if (regs->gprs[1] == -ERESTARTNOHAND ||
		    regs->gprs[1] == -ERESTARTSYS ||
		    regs->gprs[1] == -ERESTARTNOINTR) {
			RESTART_OR32_SYS(regs);
		}
		if (regs->gprs[1] == -ERESTART_RESTARTBLOCK){
		  /* look at cris port how to handle this */
		  printk("do_signal: (%s:%d): don't know how to handle ERESTART_RESTARTBLOCK\n",
			 __FILE__, __LINE__);
                }
	}
 
	return 0;
}