arch/powerpc/kernel/signal_32.c

/*
 * Signal handling for 32bit PPC and 32bit tasks on 64bit PPC
 *
 *  PowerPC version
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 * Copyright (C) 2001 IBM
 * Copyright (C) 1997,1998 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
 * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
 *
 *  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/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/elf.h>
#include <linux/ptrace.h>
#ifdef CONFIG_PPC64
#include <linux/syscalls.h>
#include <linux/compat.h>
#else
#include <linux/wait.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/freezer.h>
#endif

#include <asm/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/syscalls.h>
#include <asm/sigcontext.h>
#include <asm/vdso.h>
#ifdef CONFIG_PPC64
#include "ppc32.h"
#include <asm/unistd.h>
#else
#include <asm/ucontext.h>
#include <asm/pgtable.h>
#endif

#include "signal.h"

#undef DEBUG_SIG

#ifdef CONFIG_PPC64
#define sys_sigsuspend	compat_sys_sigsuspend
#define sys_rt_sigsuspend	compat_sys_rt_sigsuspend
#define sys_rt_sigreturn	compat_sys_rt_sigreturn
#define sys_sigaction	compat_sys_sigaction
#define sys_swapcontext	compat_sys_swapcontext
#define sys_sigreturn	compat_sys_sigreturn

#define old_sigaction	old_sigaction32
#define sigcontext	sigcontext32
#define mcontext	mcontext32
#define ucontext	ucontext32

/*
 * Returning 0 means we return to userspace via
 * ret_from_except and thus restore all user
 * registers from *regs.  This is what we need
 * to do when a signal has been delivered.
 */

#define GP_REGS_SIZE	min(sizeof(elf_gregset_t32), sizeof(struct pt_regs32))
#undef __SIGNAL_FRAMESIZE
#define __SIGNAL_FRAMESIZE	__SIGNAL_FRAMESIZE32
#undef ELF_NVRREG
#define ELF_NVRREG	ELF_NVRREG32

/*
 * Functions for flipping sigsets (thanks to brain dead generic
 * implementation that makes things simple for little endian only)
 */
static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
{
	compat_sigset_t	cset;

	switch (_NSIG_WORDS) {
	case 4: cset.sig[5] = set->sig[3] & 0xffffffffull;
		cset.sig[7] = set->sig[3] >> 32;
	case 3: cset.sig[4] = set->sig[2] & 0xffffffffull;
		cset.sig[5] = set->sig[2] >> 32;
	case 2: cset.sig[2] = set->sig[1] & 0xffffffffull;
		cset.sig[3] = set->sig[1] >> 32;
	case 1: cset.sig[0] = set->sig[0] & 0xffffffffull;
		cset.sig[1] = set->sig[0] >> 32;
	}
	return copy_to_user(uset, &cset, sizeof(*uset));
}

static inline int get_sigset_t(sigset_t *set,
			       const compat_sigset_t __user *uset)
{
	compat_sigset_t s32;

	if (copy_from_user(&s32, uset, sizeof(*uset)))
		return -EFAULT;

	/*
	 * Swap the 2 words of the 64-bit sigset_t (they are stored
	 * in the "wrong" endian in 32-bit user storage).
	 */
	switch (_NSIG_WORDS) {
	case 4: set->sig[3] = s32.sig[6] | (((long)s32.sig[7]) << 32);
	case 3: set->sig[2] = s32.sig[4] | (((long)s32.sig[5]) << 32);
	case 2: set->sig[1] = s32.sig[2] | (((long)s32.sig[3]) << 32);
	case 1: set->sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32);
	}
	return 0;
}

static inline int get_old_sigaction(struct k_sigaction *new_ka,
		struct old_sigaction __user *act)
{
	compat_old_sigset_t mask;
	compat_uptr_t handler, restorer;

	if (get_user(handler, &act->sa_handler) ||
	    __get_user(restorer, &act->sa_restorer) ||
	    __get_user(new_ka->sa.sa_flags, &act->sa_flags) ||
	    __get_user(mask, &act->sa_mask))
		return -EFAULT;
	new_ka->sa.sa_handler = compat_ptr(handler);
	new_ka->sa.sa_restorer = compat_ptr(restorer);
	siginitset(&new_ka->sa.sa_mask, mask);
	return 0;
}

#define to_user_ptr(p)		ptr_to_compat(p)
#define from_user_ptr(p)	compat_ptr(p)

static inline int save_general_regs(struct pt_regs *regs,
		struct mcontext __user *frame)
{
	elf_greg_t64 *gregs = (elf_greg_t64 *)regs;
	int i;

	WARN_ON(!FULL_REGS(regs));

	for (i = 0; i <= PT_RESULT; i ++) {
		if (i == 14 && !FULL_REGS(regs))
			i = 32;
		if (__put_user((unsigned int)gregs[i], &frame->mc_gregs[i]))
			return -EFAULT;
	}
	return 0;
}

static inline int restore_general_regs(struct pt_regs *regs,
		struct mcontext __user *sr)
{
	elf_greg_t64 *gregs = (elf_greg_t64 *)regs;
	int i;

	for (i = 0; i <= PT_RESULT; i++) {
		if ((i == PT_MSR) || (i == PT_SOFTE))
			continue;
		if (__get_user(gregs[i], &sr->mc_gregs[i]))
			return -EFAULT;
	}
	return 0;
}

#else /* CONFIG_PPC64 */

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

static inline int put_sigset_t(sigset_t __user *uset, sigset_t *set)
{
	return copy_to_user(uset, set, sizeof(*uset));
}

static inline int get_sigset_t(sigset_t *set, const sigset_t __user *uset)
{
	return copy_from_user(set, uset, sizeof(*uset));
}

static inline int get_old_sigaction(struct k_sigaction *new_ka,
		struct old_sigaction __user *act)
{
	old_sigset_t mask;

	if (!access_ok(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);
	return 0;
}

#define to_user_ptr(p)		((unsigned long)(p))
#define from_user_ptr(p)	((void __user *)(p))

static inline int save_general_regs(struct pt_regs *regs,
		struct mcontext __user *frame)
{
	WARN_ON(!FULL_REGS(regs));
	return __copy_to_user(&frame->mc_gregs, regs, GP_REGS_SIZE);
}

static inline int restore_general_regs(struct pt_regs *regs,
		struct mcontext __user *sr)
{
	/* copy up to but not including MSR */
	if (__copy_from_user(regs, &sr->mc_gregs,
				PT_MSR * sizeof(elf_greg_t)))
		return -EFAULT;
	/* 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 -EFAULT;
	return 0;
}

#endif /* CONFIG_PPC64 */

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */
long sys_sigsuspend(old_sigset_t mask)
{
	mask &= _BLOCKABLE;
	spin_lock_irq(&current->sighand->siglock);
	current->saved_sigmask = current->blocked;
	siginitset(&current->blocked, mask);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

 	current->state = TASK_INTERRUPTIBLE;
 	schedule();
	set_restore_sigmask();
 	return -ERESTARTNOHAND;
}

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

#ifdef CONFIG_PPC64
	if (sig < 0)
		sig = -sig;
#endif

	if (act) {
		if (get_old_sigaction(&new_ka, act))
			return -EFAULT;
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
	if (!ret && oact) {
		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(to_user_ptr(old_ka.sa.sa_handler),
			    &oact->sa_handler) ||
		    __put_user(to_user_ptr(old_ka.sa.sa_restorer),
			    &oact->sa_restorer) ||
		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
			return -EFAULT;
	}

	return ret;
}

/*
 * When we have signals to deliver, we set up on the
 * user stack, going down from the original stack pointer:
 *	an ABI gap of 56 words
 *	an mcontext struct
 *	a sigcontext struct
 *	a gap of __SIGNAL_FRAMESIZE bytes
 *
 * Each of these things must be a multiple of 16 bytes in size. The following
 * structure represent all of this except the __SIGNAL_FRAMESIZE gap
 *
 */
struct sigframe {
	struct sigcontext sctx;		/* the sigcontext */
	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 {
#ifdef CONFIG_PPC64
	compat_siginfo_t info;
#else
	struct siginfo info;
#endif
	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)
{
	unsigned long msr = regs->msr;
#ifdef CONFIG_VSX
	double buf[32];
	int i;
#endif

	/* Make sure floating point registers are stored in regs */
	flush_fp_to_thread(current);

	/* save general registers */
	if (save_general_regs(regs, frame))
		return 1;

#ifdef CONFIG_ALTIVEC
	/* save altivec registers */
	if (current->thread.used_vr) {
		flush_altivec_to_thread(current);
		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 */
		msr |= MSR_VEC;
	}
	/* 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_VSX
	/* save FPR copy to local buffer then write to the thread_struct */
	flush_fp_to_thread(current);
	for (i = 0; i < 32 ; i++)
		buf[i] = current->thread.TS_FPR(i);
	memcpy(&buf[i], &current->thread.fpscr, sizeof(double));
	if (__copy_to_user(&frame->mc_fregs, buf, ELF_NFPREG * sizeof(double)))
		return 1;
#else
	/* save floating-point registers */
	if (__copy_to_user(&frame->mc_fregs, current->thread.fpr,
		    ELF_NFPREG * sizeof(double)))
		return 1;
#endif /* CONFIG_VSX */
#ifdef CONFIG_SPE
	/* save spe registers */
	if (current->thread.used_spe) {
		flush_spe_to_thread(current);
		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 */
		msr |= MSR_SPE;
	}
	/* else assert((regs->msr & MSR_SPE) == 0) */

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

	if (__put_user(msr, &frame->mc_gregs[PT_MSR]))
		return 1;
	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 long restore_user_regs(struct pt_regs *regs,
			      struct mcontext __user *sr, int sig)
{
	long err;
	unsigned int save_r2 = 0;
	unsigned long msr;
#ifdef CONFIG_VSX
	double buf[32];
	int i;
#endif

	/*
	 * restore general registers but not including MSR or SOFTE. Also
	 * take care of keeping r2 (TLS) intact if not a signal
	 */
	if (!sig)
		save_r2 = (unsigned int)regs->gpr[2];
	err = restore_general_regs(regs, sr);
	err |= __get_user(msr, &sr->mc_gregs[PT_MSR]);
	if (!sig)
		regs->gpr[2] = (unsigned long) save_r2;
	if (err)
		return 1;

	/* if doing signal return, restore the previous little-endian mode */
	if (sig)
		regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);

	/*
	 * Do this before updating the thread state in
	 * current->thread.fpr/vr/evr.  That way, if we get preempted
	 * and another task grabs the FPU/Altivec/SPE, it won't be
	 * tempted to save the current CPU state into the thread_struct
	 * and corrupt what we are writing there.
	 */
	discard_lazy_cpu_state();

#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 (msr & MSR_VEC) {
		/* 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_VSX
	if (__copy_from_user(buf, &sr->mc_fregs,sizeof(sr->mc_fregs)))
		return 1;
	for (i = 0; i < 32 ; i++)
		current->thread.TS_FPR(i) = buf[i];
	memcpy(&current->thread.fpscr, &buf[i], sizeof(double));
#else
	if (__copy_from_user(current->thread.fpr, &sr->mc_fregs,
			     sizeof(sr->mc_fregs)))
		return 1;
#endif /* CONFIG_VSX */
	/*
	 * force the process to reload the FP registers from
	 * current->thread when it next does FP instructions
	 */
	regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1);

#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 (msr & MSR_SPE) {
		/* restore spe registers from the stack */
		if (__copy_from_user(current->thread.evr, &sr->mc_vregs,
				     ELF_NEVRREG * sizeof(u32)))
			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 __user *)&sr->mc_vregs + ELF_NEVRREG))
		return 1;
#endif /* CONFIG_SPE */

	return 0;
}

#ifdef CONFIG_PPC64
long compat_sys_rt_sigaction(int sig, const struct sigaction32 __user *act,
		struct sigaction32 __user *oact, size_t sigsetsize)
{
	struct k_sigaction new_ka, old_ka;
	int ret;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(compat_sigset_t))
		return -EINVAL;

	if (act) {
		compat_uptr_t handler;

		ret = get_user(handler, &act->sa_handler);
		new_ka.sa.sa_handler = compat_ptr(handler);
		ret |= get_sigset_t(&new_ka.sa.sa_mask, &act->sa_mask);
		ret |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
		if (ret)
			return -EFAULT;
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
	if (!ret && oact) {
		ret = put_user(to_user_ptr(old_ka.sa.sa_handler), &oact->sa_handler);
		ret |= put_sigset_t(&oact->sa_mask, &old_ka.sa.sa_mask);
		ret |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
	}
	return ret;
}

/*
 * Note: it is necessary to treat how as an unsigned int, with the
 * corresponding cast to a signed int to insure that the proper
 * conversion (sign extension) between the register representation
 * of a signed int (msr in 32-bit mode) and the register representation
 * of a signed int (msr in 64-bit mode) is performed.
 */
long compat_sys_rt_sigprocmask(u32 how, compat_sigset_t __user *set,
		compat_sigset_t __user *oset, size_t sigsetsize)
{
	sigset_t s;
	sigset_t __user *up;
	int ret;
	mm_segment_t old_fs = get_fs();

	if (set) {
		if (get_sigset_t(&s, set))
			return -EFAULT;
	}

	set_fs(KERNEL_DS);
	/* This is valid because of the set_fs() */
	up = (sigset_t __user *) &s;
	ret = sys_rt_sigprocmask((int)how, set ? up : NULL, oset ? up : NULL,
				 sigsetsize);
	set_fs(old_fs);
	if (ret)
		return ret;
	if (oset) {
		if (put_sigset_t(oset, &s))
			return -EFAULT;
	}
	return 0;
}

long compat_sys_rt_sigpending(compat_sigset_t __user *set, compat_size_t sigsetsize)
{
	sigset_t s;
	int ret;
	mm_segment_t old_fs = get_fs();

	set_fs(KERNEL_DS);
	/* The __user pointer cast is valid because of the set_fs() */
	ret = sys_rt_sigpending((sigset_t __user *) &s, sigsetsize);
	set_fs(old_fs);
	if (!ret) {
		if (put_sigset_t(set, &s))
			return -EFAULT;
	}
	return ret;
}


int copy_siginfo_to_user32(struct compat_siginfo __user *d, siginfo_t *s)
{
	int err;

	if (!access_ok (VERIFY_WRITE, d, sizeof(*d)))
		return -EFAULT;

	/* If you change siginfo_t structure, please be sure
	 * this code is fixed accordingly.
	 * It should never copy any pad contained in the structure
	 * to avoid security leaks, but must copy the generic
	 * 3 ints plus the relevant union member.
	 * This routine must convert siginfo from 64bit to 32bit as well
	 * at the same time.
	 */
	err = __put_user(s->si_signo, &d->si_signo);
	err |= __put_user(s->si_errno, &d->si_errno);
	err |= __put_user((short)s->si_code, &d->si_code);
	if (s->si_code < 0)
		err |= __copy_to_user(&d->_sifields._pad, &s->_sifields._pad,
				      SI_PAD_SIZE32);
	else switch(s->si_code >> 16) {
	case __SI_CHLD >> 16:
		err |= __put_user(s->si_pid, &d->si_pid);
		err |= __put_user(s->si_uid, &d->si_uid);
		err |= __put_user(s->si_utime, &d->si_utime);
		err |= __put_user(s->si_stime, &d->si_stime);
		err |= __put_user(s->si_status, &d->si_status);
		break;
	case __SI_FAULT >> 16:
		err |= __put_user((unsigned int)(unsigned long)s->si_addr,
				  &d->si_addr);
		break;
	case __SI_POLL >> 16:
		err |= __put_user(s->si_band, &d->si_band);
		err |= __put_user(s->si_fd, &d->si_fd);
		break;
	case __SI_TIMER >> 16:
		err |= __put_user(s->si_tid, &d->si_tid);
		err |= __put_user(s->si_overrun, &d->si_overrun);
		err |= __put_user(s->si_int, &d->si_int);
		break;
	case __SI_RT >> 16: /* This is not generated by the kernel as of now.  */
	case __SI_MESGQ >> 16:
		err |= __put_user(s->si_int, &d->si_int);
		/* fallthrough */
	case __SI_KILL >> 16:
	default:
		err |= __put_user(s->si_pid, &d->si_pid);
		err |= __put_user(s->si_uid, &d->si_uid);
		break;
	}
	return err;
}

#define copy_siginfo_to_user	copy_siginfo_to_user32

int copy_siginfo_from_user32(siginfo_t *to, struct compat_siginfo __user *from)
{
	memset(to, 0, sizeof *to);

	if (copy_from_user(to, from, 3*sizeof(int)) ||
	    copy_from_user(to->_sifields._pad,
			   from->_sifields._pad, SI_PAD_SIZE32))
		return -EFAULT;

	return 0;
}

/*
 * Note: it is necessary to treat pid and sig as unsigned ints, with the
 * corresponding cast to a signed int to insure that the proper conversion
 * (sign extension) between the register representation of a signed int
 * (msr in 32-bit mode) and the register representation of a signed int
 * (msr in 64-bit mode) is performed.
 */
long compat_sys_rt_sigqueueinfo(u32 pid, u32 sig, compat_siginfo_t __user *uinfo)
{
	siginfo_t info;
	int ret;
	mm_segment_t old_fs = get_fs();

	ret = copy_siginfo_from_user32(&info, uinfo);
	if (unlikely(ret))
		return ret;

	set_fs (KERNEL_DS);
	/* The __user pointer cast is valid becasuse of the set_fs() */
	ret = sys_rt_sigqueueinfo((int)pid, (int)sig, (siginfo_t __user *) &info);
	set_fs (old_fs);
	return ret;
}
/*
 *  Start Alternate signal stack support
 *
 *  System Calls
 *       sigaltatck               compat_sys_sigaltstack
 */

int compat_sys_sigaltstack(u32 __new, u32 __old, int r5,
		      int r6, int r7, int r8, struct pt_regs *regs)
{
	stack_32_t __user * newstack = compat_ptr(__new);
	stack_32_t __user * oldstack = compat_ptr(__old);
	stack_t uss, uoss;
	int ret;
	mm_segment_t old_fs;
	unsigned long sp;
	compat_uptr_t ss_sp;

	/*
	 * set sp to the user stack on entry to the system call
	 * the system call router sets R9 to the saved registers
	 */
	sp = regs->gpr[1];

	/* Put new stack info in local 64 bit stack struct */
	if (newstack) {
		if (get_user(ss_sp, &newstack->ss_sp) ||
		    __get_user(uss.ss_flags, &newstack->ss_flags) ||
		    __get_user(uss.ss_size, &newstack->ss_size))
			return -EFAULT;
		uss.ss_sp = compat_ptr(ss_sp);
	}

	old_fs = get_fs();
	set_fs(KERNEL_DS);
	/* The __user pointer casts are valid because of the set_fs() */
	ret = do_sigaltstack(
		newstack ? (stack_t __user *) &uss : NULL,
		oldstack ? (stack_t __user *) &uoss : NULL,
		sp);
	set_fs(old_fs);
	/* Copy the stack information to the user output buffer */
	if (!ret && oldstack  &&
		(put_user(ptr_to_compat(uoss.ss_sp), &oldstack->ss_sp) ||
		 __put_user(uoss.ss_flags, &oldstack->ss_flags) ||
		 __put_user(uoss.ss_size, &oldstack->ss_size)))
		return -EFAULT;
	return ret;
}
#endif /* CONFIG_PPC64 */

/*
 * Set up a signal frame for a "real-time" signal handler
 * (one which gets siginfo).
 */
int handle_rt_signal32(unsigned long sig, struct k_sigaction *ka,
		siginfo_t *info, sigset_t *oldset,
		struct pt_regs *regs)
{
	struct rt_sigframe __user *rt_sf;
	struct mcontext __user *frame;
	void __user *addr;
	unsigned long newsp = 0;

	/* Set up Signal Frame */
	/* Put a Real Time Context onto stack */
	rt_sf = get_sigframe(ka, regs, sizeof(*rt_sf));
	addr = rt_sf;
	if (unlikely(rt_sf == NULL))
		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(to_user_ptr(&rt_sf->uc.uc_mcontext),
		    &rt_sf->uc.uc_regs)
	    || put_sigset_t(&rt_sf->uc.uc_sigmask, oldset))
		goto badframe;

	/* Save user registers on the stack */
	frame = &rt_sf->uc.uc_mcontext;
	addr = frame;
	if (vdso32_rt_sigtramp && current->mm->context.vdso_base) {
		if (save_user_regs(regs, frame, 0))
			goto badframe;
		regs->link = current->mm->context.vdso_base + vdso32_rt_sigtramp;
	} else {
		if (save_user_regs(regs, frame, __NR_rt_sigreturn))
			goto badframe;
		regs->link = (unsigned long) frame->tramp;
	}

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

	/* create a stack frame for the caller of the handler */
	newsp = ((unsigned long)rt_sf) - (__SIGNAL_FRAMESIZE + 16);
	addr = (void __user *)regs->gpr[1];
	if (put_user(regs->gpr[1], (u32 __user *)newsp))
		goto badframe;

	/* Fill registers for signal handler */
	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;
	/* 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;
}