/*
 *  arch/ppc/kernel/signal.c
 *
 *  PowerPC version
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Derived from "arch/i386/kernel/signal.c"
 *    Copyright (C) 1991, 1992 Linus Torvalds
 *    1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#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 <linux/elf.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>

#undef DEBUG_SIG

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

extern void sigreturn_exit(struct pt_regs *);

#define GP_REGS_SIZE	min(sizeof(elf_gregset_t), sizeof(struct pt_regs))

int do_signal(sigset_t *oldset, struct pt_regs *regs);

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */
int
sys_sigsuspend(old_sigset_t mask, int p2, int p3, int p4, int p6, int p7,
	       struct pt_regs *regs)
{
	sigset_t saveset;

	mask &= _BLOCKABLE;
	spin_lock_irq(&current->sighand->siglock);
	saveset = current->blocked;
	siginitset(&current->blocked, mask);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	regs->result = -EINTR;
	regs->gpr[3] = EINTR;
	regs->ccr |= 0x10000000;
	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(&saveset, regs))
			sigreturn_exit(regs);
	}
}

int
sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, int p3, int p4,
		  int p6, int p7, struct pt_regs *regs)
{
	sigset_t saveset, newset;

	/* 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->result = -EINTR;
	regs->gpr[3] = EINTR;
	regs->ccr |= 0x10000000;
	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(&saveset, regs))
			sigreturn_exit(regs);
	}
}


int
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, int r5,
		int r6, int r7, int r8, struct pt_regs *regs)
{
	return do_sigaltstack(uss, uoss, regs->gpr[1]);
}

int
sys_sigaction(int sig, const struct old_sigaction __user *act,
	      struct old_sigaction __user *oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;

	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;
}

/*
 * When we have signals to deliver, we set up on the
 * user stack, going down from the original stack pointer:
 *	a sigregs struct
 *	a sigcontext struct
 *	a gap of __SIGNAL_FRAMESIZE bytes
 *
 * Each of these things must be a multiple of 16 bytes in size.
 *
 */
struct sigregs {
	struct mcontext	mctx;		/* all the register values */
	/* Programs using the rs6000/xcoff abi can save up to 19 gp regs
	   and 18 fp regs below sp before decrementing it. */
	int		abigap[56];
};

/* We use the mc_pad field for the signal return trampoline. */
#define tramp	mc_pad

/*
 *  When we have rt signals to deliver, we set up on the
 *  user stack, going down from the original stack pointer:
 *	one rt_sigframe struct (siginfo + ucontext + ABI gap)
 *	a gap of __SIGNAL_FRAMESIZE+16 bytes
 *  (the +16 is to get the siginfo and ucontext in the same
 *  positions as in older kernels).
 *
 *  Each of these things must be a multiple of 16 bytes in size.
 *
 */
struct rt_sigframe
{
	struct siginfo info;
	struct ucontext uc;
	/* Programs using the rs6000/xcoff abi can save up to 19 gp regs
	   and 18 fp regs below sp before decrementing it. */
	int		abigap[56];
};

/*
 * Save the current user registers on the user stack.
 * We only save the altivec/spe registers if the process has used
 * altivec/spe instructions at some point.
 */
static int
save_user_regs(struct pt_regs *regs, struct mcontext __user *frame, int sigret)
{
	/* save general and floating-point registers */
	CHECK_FULL_REGS(regs);
	preempt_disable();
	if (regs->msr & MSR_FP)
		giveup_fpu(current);
#ifdef CONFIG_ALTIVEC
	if (current->thread.used_vr && (regs->msr & MSR_VEC))
		giveup_altivec(current);
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
	if (current->thread.used_spe && (regs->msr & MSR_SPE))
		giveup_spe(current);
#endif /* CONFIG_ALTIVEC */
	preempt_enable();

	if (__copy_to_user(&frame->mc_gregs, regs, GP_REGS_SIZE)
	    || __copy_to_user(&frame->mc_fregs, current->thread.fpr,
			      ELF_NFPREG * sizeof(double)))
		return 1;

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

#ifdef CONFIG_ALTIVEC
	/* save altivec registers */
	if (current->thread.used_vr) {
		if (__copy_to_user(&frame->mc_vregs, current->thread.vr,
				   ELF_NVRREG * sizeof(vector128)))
			return 1;
		/* set MSR_VEC in the saved MSR value to indicate that
		   frame->mc_vregs contains valid data */
		if (__put_user(regs->msr | MSR_VEC, &frame->mc_gregs[PT_MSR]))
			return 1;
	}
	/* else assert((regs->msr & MSR_VEC) == 0) */

	/* We always copy to/from vrsave, it's 0 if we don't have or don't
	 * use altivec. Since VSCR only contains 32 bits saved in the least
	 * significant bits of a vector, we "cheat" and stuff VRSAVE in the
	 * most significant bits of that same vector. --BenH
	 */
	if (__put_user(current->thread.vrsave, (u32 __user *)&frame->mc_vregs[32]))
		return 1;
#endif /* CONFIG_ALTIVEC */

#ifdef CONFIG_SPE
	/* save spe registers */
	if (current->thread.used_spe) {
		if (__copy_to_user(&frame->mc_vregs, current->thread.evr,
				   ELF_NEVRREG * sizeof(u32)))
			return 1;
		/* set MSR_SPE in the saved MSR value to indicate that
		   frame->mc_vregs contains valid data */
		if (__put_user(regs->msr | MSR_SPE, &frame->mc_gregs[PT_MSR]))
			return 1;
	}
	/* else assert((regs->msr & MSR_SPE) == 0) */

	/* We always copy to/from spefscr */
	if (__put_user(current->thread.spefscr, (u32 *)&frame->mc_vregs + ELF_NEVRREG))
		return 1;
#endif /* CONFIG_SPE */

	if (sigret) {
		/* Set up the sigreturn trampoline: li r0,sigret; sc */
		if (__put_user(0x38000000UL + sigret, &frame->tramp[0])
		    || __put_user(0x44000002UL, &frame->tramp[1]))
			return 1;
		flush_icache_range((unsigned long) &frame->tramp[0],
				   (unsigned long) &frame->tramp[2]);
	}

	return 0;
}

/*
 * Restore the current user register values from the user stack,
 * (except for MSR).
 */
static int
restore_user_regs(struct pt_regs *regs, struct mcontext __user *sr, int sig)
{
	unsigned long save_r2;
#if defined(CONFIG_ALTIVEC) || defined(CONFIG_SPE)
	unsigned long msr;
#endif

	/* backup/restore the TLS as we don't want it to be modified */
	if (!sig)
		save_r2 = regs->gpr[2];
	/* copy up to but not including MSR */
	if (__copy_from_user(regs, &sr->mc_gregs, PT_MSR * sizeof(elf_greg_t)))
		return 1;
	/* copy from orig_r3 (the word after the MSR) up to the end */
	if (__copy_from_user(&regs->orig_gpr3, &sr->mc_gregs[PT_ORIG_R3],
			     GP_REGS_SIZE - PT_ORIG_R3 * sizeof(elf_greg_t)))
		return 1;
	if (!sig)
		regs->gpr[2] = save_r2;

	/* force the process to reload the FP registers from
	   current->thread when it next does FP instructions */
	regs->msr &= ~MSR_FP;
	if (__copy_from_user(current->thread.fpr, &sr->mc_fregs,
			     sizeof(sr->mc_fregs)))
		return 1;

#ifdef CONFIG_ALTIVEC
	/* force the process to reload the altivec registers from
	   current->thread when it next does altivec instructions */
	regs->msr &= ~MSR_VEC;
	if (!__get_user(msr, &sr->mc_gregs[PT_MSR]) && (msr & MSR_VEC) != 0) {
		/* restore altivec registers from the stack */
		if (__copy_from_user(current->thread.vr, &sr->mc_vregs,
				     sizeof(sr->mc_vregs)))
			return 1;
	} else if (current->thread.used_vr)
		memset(&current->thread.vr, 0, ELF_NVRREG * sizeof(vector128));

	/* Always get VRSAVE back */
	if (__get_user(current->thread.vrsave, (u32 __user *)&sr->mc_vregs[32]))
		return 1;
#endif /* CONFIG_ALTIVEC */

#ifdef CONFIG_SPE
	/* force the process to reload the spe registers from
	   current->thread when it next does spe instructions */
	regs->msr &= ~MSR_SPE;
	if (!__get_user(msr, &sr->mc_gregs[PT_MSR]) && (msr & MSR_SPE) != 0) {
		/* restore spe registers from the stack */
		if (__copy_from_user(current->thread.evr, &sr->mc_vregs,
				     sizeof(sr->mc_vregs)))
			return 1;
	} else if (current->thread.used_spe)
		memset(&current->thread.evr, 0, ELF_NEVRREG * sizeof(u32));

	/* Always get SPEFSCR back */
	if (__get_user(current->thread.spefscr, (u32 *)&sr->mc_vregs + ELF_NEVRREG))
		return 1;
#endif /* CONFIG_SPE */

	return 0;
}

/*
 * Restore the user process's signal mask
 */
static void
restore_sigmask(sigset_t *set)
{
	sigdelsetmask(set, ~_BLOCKABLE);
	spin_lock_irq(&current->sighand->siglock);
	current->blocked = *set;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
}

/*
 * Set up a signal frame for a "real-time" signal handler
 * (one which gets siginfo).
 */
static void
handle_rt_signal(unsigned long sig, struct k_sigaction *ka,
		 siginfo_t *info, sigset_t *oldset, struct pt_regs * regs,
		 unsigned long newsp)
{
	struct rt_sigframe __user *rt_sf;
	struct mcontext __user *frame;
	unsigned long origsp = newsp;

	/* Set up Signal Frame */
	/* Put a Real Time Context onto stack */
	newsp -= sizeof(*rt_sf);
	rt_sf = (struct rt_sigframe __user *) newsp;

	/* create a stack frame for the caller of the handler */
	newsp -= __SIGNAL_FRAMESIZE + 16;

	if (verify_area(VERIFY_WRITE, (void __user *) newsp, origsp - newsp))
		goto badframe;

	/* Put the siginfo & fill in most of the ucontext */
	if (copy_siginfo_to_user(&rt_sf->info, info)
	    || __put_user(0, &rt_sf->uc.uc_flags)
	    || __put_user(0, &rt_sf->uc.uc_link)
	    || __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
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	force_sig(SIGSEGV, 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 (verify_area(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 (verify_area(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 verify_area
	 * 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 (verify_area(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;
}

/*
 * 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 (verify_area(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 *)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
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	force_sig(SIGSEGV, 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 (verify_area(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 (!oldset)
		oldset = &current->blocked;

	newsp = frame = 0;

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

	ka = (signr == 0)? NULL: &current->sighand->action[signr-1];

	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);

	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, signr);
		recalc_sigpending();
		spin_unlock_irq(&current->sighand->siglock);
	}

	return 1;
}

