Merge branch 'akpm'

[linux-2.6/next.git] / arch / ia64 / kernel / ptrace.c

/*
 * Kernel support for the ptrace() and syscall tracing interfaces.
 *
 * Copyright (C) 1999-2005 Hewlett-Packard Co
 *      David Mosberger-Tang <davidm@hpl.hp.com>
 * Copyright (C) 2006 Intel Co
 *  2006-08-12  - IA64 Native Utrace implementation support added by
 *      Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
 *
 * Derived from the x86 and Alpha versions.
 */
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/audit.h>
#include <linux/signal.h>
#include <linux/regset.h>
#include <linux/elf.h>
#include <linux/tracehook.h>

#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/ptrace_offsets.h>
#include <asm/rse.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/unwind.h>
#ifdef CONFIG_PERFMON
#include <asm/perfmon.h>
#endif

#include "entry.h"

/*
 * Bits in the PSR that we allow ptrace() to change:
 *      be, up, ac, mfl, mfh (the user mask; five bits total)
 *      db (debug breakpoint fault; one bit)
 *      id (instruction debug fault disable; one bit)
 *      dd (data debug fault disable; one bit)
 *      ri (restart instruction; two bits)
 *      is (instruction set; one bit)
 */
#define IPSR_MASK (IA64_PSR_UM | IA64_PSR_DB | IA64_PSR_IS      \
                   | IA64_PSR_ID | IA64_PSR_DD | IA64_PSR_RI)

#define MASK(nbits)     ((1UL << (nbits)) - 1)  /* mask with NBITS bits set */
#define PFM_MASK        MASK(38)

#define PTRACE_DEBUG    0

#if PTRACE_DEBUG
# define dprintk(format...)     printk(format)
# define inline
#else
# define dprintk(format...)
#endif

/* Return TRUE if PT was created due to kernel-entry via a system-call.  */

static inline int
in_syscall (struct pt_regs *pt)
{
        return (long) pt->cr_ifs >= 0;
}

/*
 * Collect the NaT bits for r1-r31 from scratch_unat and return a NaT
 * bitset where bit i is set iff the NaT bit of register i is set.
 */
unsigned long
ia64_get_scratch_nat_bits (struct pt_regs *pt, unsigned long scratch_unat)
{
#       define GET_BITS(first, last, unat)                              \
        ({                                                              \
                unsigned long bit = ia64_unat_pos(&pt->r##first);       \
                unsigned long nbits = (last - first + 1);               \
                unsigned long mask = MASK(nbits) << first;              \
                unsigned long dist;                                     \
                if (bit < first)                                        \
                        dist = 64 + bit - first;                        \
                else                                                    \
                        dist = bit - first;                             \
                ia64_rotr(unat, dist) & mask;                           \
        })
        unsigned long val;

        /*
         * Registers that are stored consecutively in struct pt_regs
         * can be handled in parallel.  If the register order in
         * struct_pt_regs changes, this code MUST be updated.
         */
        val  = GET_BITS( 1,  1, scratch_unat);
        val |= GET_BITS( 2,  3, scratch_unat);
        val |= GET_BITS(12, 13, scratch_unat);
        val |= GET_BITS(14, 14, scratch_unat);
        val |= GET_BITS(15, 15, scratch_unat);
        val |= GET_BITS( 8, 11, scratch_unat);
        val |= GET_BITS(16, 31, scratch_unat);
        return val;

#       undef GET_BITS
}

/*
 * Set the NaT bits for the scratch registers according to NAT and
 * return the resulting unat (assuming the scratch registers are
 * stored in PT).
 */
unsigned long
ia64_put_scratch_nat_bits (struct pt_regs *pt, unsigned long nat)
{
#       define PUT_BITS(first, last, nat)                               \
        ({                                                              \
                unsigned long bit = ia64_unat_pos(&pt->r##first);       \
                unsigned long nbits = (last - first + 1);               \
                unsigned long mask = MASK(nbits) << first;              \
                long dist;                                              \
                if (bit < first)                                        \
                        dist = 64 + bit - first;                        \
                else                                                    \
                        dist = bit - first;                             \
                ia64_rotl(nat & mask, dist);                            \
        })
        unsigned long scratch_unat;

        /*
         * Registers that are stored consecutively in struct pt_regs
         * can be handled in parallel.  If the register order in
         * struct_pt_regs changes, this code MUST be updated.
         */
        scratch_unat  = PUT_BITS( 1,  1, nat);
        scratch_unat |= PUT_BITS( 2,  3, nat);
        scratch_unat |= PUT_BITS(12, 13, nat);
        scratch_unat |= PUT_BITS(14, 14, nat);
        scratch_unat |= PUT_BITS(15, 15, nat);
        scratch_unat |= PUT_BITS( 8, 11, nat);
        scratch_unat |= PUT_BITS(16, 31, nat);

        return scratch_unat;

#       undef PUT_BITS
}

#define IA64_MLX_TEMPLATE       0x2
#define IA64_MOVL_OPCODE        6

void
ia64_increment_ip (struct pt_regs *regs)
{
        unsigned long w0, ri = ia64_psr(regs)->ri + 1;

        if (ri > 2) {
                ri = 0;
                regs->cr_iip += 16;
        } else if (ri == 2) {
                get_user(w0, (char __user *) regs->cr_iip + 0);
                if (((w0 >> 1) & 0xf) == IA64_MLX_TEMPLATE) {
                        /*
                         * rfi'ing to slot 2 of an MLX bundle causes
                         * an illegal operation fault.  We don't want
                         * that to happen...
                         */
                        ri = 0;
                        regs->cr_iip += 16;
                }
        }
        ia64_psr(regs)->ri = ri;
}

void
ia64_decrement_ip (struct pt_regs *regs)
{
        unsigned long w0, ri = ia64_psr(regs)->ri - 1;

        if (ia64_psr(regs)->ri == 0) {
                regs->cr_iip -= 16;
                ri = 2;
                get_user(w0, (char __user *) regs->cr_iip + 0);
                if (((w0 >> 1) & 0xf) == IA64_MLX_TEMPLATE) {
                        /*
                         * rfi'ing to slot 2 of an MLX bundle causes
                         * an illegal operation fault.  We don't want
                         * that to happen...
                         */
                        ri = 1;
                }
        }
        ia64_psr(regs)->ri = ri;
}

/*
 * This routine is used to read an rnat bits that are stored on the
 * kernel backing store.  Since, in general, the alignment of the user
 * and kernel are different, this is not completely trivial.  In
 * essence, we need to construct the user RNAT based on up to two
 * kernel RNAT values and/or the RNAT value saved in the child's
 * pt_regs.
 *
 * user rbs
 *
 * +--------+ <-- lowest address
 * | slot62 |
 * +--------+
 * |  rnat  | 0x....1f8
 * +--------+
 * | slot00 | \
 * +--------+ |
 * | slot01 | > child_regs->ar_rnat
 * +--------+ |
 * | slot02 | /                         kernel rbs
 * +--------+                           +--------+
 *          <- child_regs->ar_bspstore  | slot61 | <-- krbs
 * +- - - - +                           +--------+
 *                                      | slot62 |
 * +- - - - +                           +--------+
 *                                      |  rnat  |
 * +- - - - +                           +--------+
 *   vrnat                              | slot00 |
 * +- - - - +                           +--------+
 *                                      =        =
 *                                      +--------+
 *                                      | slot00 | \
 *                                      +--------+ |
 *                                      | slot01 | > child_stack->ar_rnat
 *                                      +--------+ |
 *                                      | slot02 | /
 *                                      +--------+
 *                                                <--- child_stack->ar_bspstore
 *
 * The way to think of this code is as follows: bit 0 in the user rnat
 * corresponds to some bit N (0 <= N <= 62) in one of the kernel rnat
 * value.  The kernel rnat value holding this bit is stored in
 * variable rnat0.  rnat1 is loaded with the kernel rnat value that
 * form the upper bits of the user rnat value.
 *
 * Boundary cases:
 *
 * o when reading the rnat "below" the first rnat slot on the kernel
 *   backing store, rnat0/rnat1 are set to 0 and the low order bits are
 *   merged in from pt->ar_rnat.
 *
 * o when reading the rnat "above" the last rnat slot on the kernel
 *   backing store, rnat0/rnat1 gets its value from sw->ar_rnat.
 */
static unsigned long
get_rnat (struct task_struct *task, struct switch_stack *sw,
          unsigned long *krbs, unsigned long *urnat_addr,
          unsigned long *urbs_end)
{
        unsigned long rnat0 = 0, rnat1 = 0, urnat = 0, *slot0_kaddr;
        unsigned long umask = 0, mask, m;
        unsigned long *kbsp, *ubspstore, *rnat0_kaddr, *rnat1_kaddr, shift;
        long num_regs, nbits;
        struct pt_regs *pt;

        pt = task_pt_regs(task);
        kbsp = (unsigned long *) sw->ar_bspstore;
        ubspstore = (unsigned long *) pt->ar_bspstore;

        if (urbs_end < urnat_addr)
                nbits = ia64_rse_num_regs(urnat_addr - 63, urbs_end);
        else
                nbits = 63;
        mask = MASK(nbits);
        /*
         * First, figure out which bit number slot 0 in user-land maps
         * to in the kernel rnat.  Do this by figuring out how many
         * register slots we're beyond the user's backingstore and
         * then computing the equivalent address in kernel space.
         */
        num_regs = ia64_rse_num_regs(ubspstore, urnat_addr + 1);
        slot0_kaddr = ia64_rse_skip_regs(krbs, num_regs);
        shift = ia64_rse_slot_num(slot0_kaddr);
        rnat1_kaddr = ia64_rse_rnat_addr(slot0_kaddr);
        rnat0_kaddr = rnat1_kaddr - 64;

        if (ubspstore + 63 > urnat_addr) {
                /* some bits need to be merged in from pt->ar_rnat */
                umask = MASK(ia64_rse_slot_num(ubspstore)) & mask;
                urnat = (pt->ar_rnat & umask);
                mask &= ~umask;
                if (!mask)
                        return urnat;
        }

        m = mask << shift;
        if (rnat0_kaddr >= kbsp)
                rnat0 = sw->ar_rnat;
        else if (rnat0_kaddr > krbs)
                rnat0 = *rnat0_kaddr;
        urnat |= (rnat0 & m) >> shift;

        m = mask >> (63 - shift);
        if (rnat1_kaddr >= kbsp)
                rnat1 = sw->ar_rnat;
        else if (rnat1_kaddr > krbs)
                rnat1 = *rnat1_kaddr;
        urnat |= (rnat1 & m) << (63 - shift);
        return urnat;
}

/*
 * The reverse of get_rnat.
 */
static void
put_rnat (struct task_struct *task, struct switch_stack *sw,
          unsigned long *krbs, unsigned long *urnat_addr, unsigned long urnat,
          unsigned long *urbs_end)
{
        unsigned long rnat0 = 0, rnat1 = 0, *slot0_kaddr, umask = 0, mask, m;
        unsigned long *kbsp, *ubspstore, *rnat0_kaddr, *rnat1_kaddr, shift;
        long num_regs, nbits;
        struct pt_regs *pt;
        unsigned long cfm, *urbs_kargs;

        pt = task_pt_regs(task);
        kbsp = (unsigned long *) sw->ar_bspstore;
        ubspstore = (unsigned long *) pt->ar_bspstore;

        urbs_kargs = urbs_end;
        if (in_syscall(pt)) {
                /*
                 * If entered via syscall, don't allow user to set rnat bits
                 * for syscall args.
                 */
                cfm = pt->cr_ifs;
                urbs_kargs = ia64_rse_skip_regs(urbs_end, -(cfm & 0x7f));
        }

        if (urbs_kargs >= urnat_addr)
                nbits = 63;
        else {
                if ((urnat_addr - 63) >= urbs_kargs)
                        return;
                nbits = ia64_rse_num_regs(urnat_addr - 63, urbs_kargs);
        }
        mask = MASK(nbits);

        /*
         * First, figure out which bit number slot 0 in user-land maps
         * to in the kernel rnat.  Do this by figuring out how many
         * register slots we're beyond the user's backingstore and
         * then computing the equivalent address in kernel space.
         */
        num_regs = ia64_rse_num_regs(ubspstore, urnat_addr + 1);
        slot0_kaddr = ia64_rse_skip_regs(krbs, num_regs);
        shift = ia64_rse_slot_num(slot0_kaddr);
        rnat1_kaddr = ia64_rse_rnat_addr(slot0_kaddr);
        rnat0_kaddr = rnat1_kaddr - 64;

        if (ubspstore + 63 > urnat_addr) {
                /* some bits need to be place in pt->ar_rnat: */
                umask = MASK(ia64_rse_slot_num(ubspstore)) & mask;
                pt->ar_rnat = (pt->ar_rnat & ~umask) | (urnat & umask);
                mask &= ~umask;
                if (!mask)
                        return;
        }
        /*
         * Note: Section 11.1 of the EAS guarantees that bit 63 of an
         * rnat slot is ignored. so we don't have to clear it here.
         */
        rnat0 = (urnat << shift);
        m = mask << shift;
        if (rnat0_kaddr >= kbsp)
                sw->ar_rnat = (sw->ar_rnat & ~m) | (rnat0 & m);
        else if (rnat0_kaddr > krbs)
                *rnat0_kaddr = ((*rnat0_kaddr & ~m) | (rnat0 & m));

        rnat1 = (urnat >> (63 - shift));
        m = mask >> (63 - shift);
        if (rnat1_kaddr >= kbsp)
                sw->ar_rnat = (sw->ar_rnat & ~m) | (rnat1 & m);
        else if (rnat1_kaddr > krbs)
                *rnat1_kaddr = ((*rnat1_kaddr & ~m) | (rnat1 & m));
}

static inline int
on_kernel_rbs (unsigned long addr, unsigned long bspstore,
               unsigned long urbs_end)
{
        unsigned long *rnat_addr = ia64_rse_rnat_addr((unsigned long *)
                                                      urbs_end);
        return (addr >= bspstore && addr <= (unsigned long) rnat_addr);
}

/*
 * Read a word from the user-level backing store of task CHILD.  ADDR
 * is the user-level address to read the word from, VAL a pointer to
 * the return value, and USER_BSP gives the end of the user-level
 * backing store (i.e., it's the address that would be in ar.bsp after
 * the user executed a "cover" instruction).
 *
 * This routine takes care of accessing the kernel register backing
 * store for those registers that got spilled there.  It also takes
 * care of calculating the appropriate RNaT collection words.
 */
long
ia64_peek (struct task_struct *child, struct switch_stack *child_stack,
           unsigned long user_rbs_end, unsigned long addr, long *val)
{
        unsigned long *bspstore, *krbs, regnum, *laddr, *urbs_end, *rnat_addr;
        struct pt_regs *child_regs;
        size_t copied;
        long ret;

        urbs_end = (long *) user_rbs_end;
        laddr = (unsigned long *) addr;
        child_regs = task_pt_regs(child);
        bspstore = (unsigned long *) child_regs->ar_bspstore;
        krbs = (unsigned long *) child + IA64_RBS_OFFSET/8;
        if (on_kernel_rbs(addr, (unsigned long) bspstore,
                          (unsigned long) urbs_end))
        {
                /*
                 * Attempt to read the RBS in an area that's actually
                 * on the kernel RBS => read the corresponding bits in
                 * the kernel RBS.
                 */
                rnat_addr = ia64_rse_rnat_addr(laddr);
                ret = get_rnat(child, child_stack, krbs, rnat_addr, urbs_end);

                if (laddr == rnat_addr) {
                        /* return NaT collection word itself */
                        *val = ret;
                        return 0;
                }

                if (((1UL << ia64_rse_slot_num(laddr)) & ret) != 0) {
                        /*
                         * It is implementation dependent whether the
                         * data portion of a NaT value gets saved on a
                         * st8.spill or RSE spill (e.g., see EAS 2.6,
                         * 4.4.4.6 Register Spill and Fill).  To get
                         * consistent behavior across all possible
                         * IA-64 implementations, we return zero in
                         * this case.
                         */
                        *val = 0;
                        return 0;
                }

                if (laddr < urbs_end) {
                        /*
                         * The desired word is on the kernel RBS and
                         * is not a NaT.
                         */
                        regnum = ia64_rse_num_regs(bspstore, laddr);
                        *val = *ia64_rse_skip_regs(krbs, regnum);
                        return 0;
                }
        }
        copied = access_process_vm(child, addr, &ret, sizeof(ret), 0);
        if (copied != sizeof(ret))
                return -EIO;
        *val = ret;
        return 0;
}

long
ia64_poke (struct task_struct *child, struct switch_stack *child_stack,
           unsigned long user_rbs_end, unsigned long addr, long val)
{
        unsigned long *bspstore, *krbs, regnum, *laddr;
        unsigned long *urbs_end = (long *) user_rbs_end;
        struct pt_regs *child_regs;

        laddr = (unsigned long *) addr;
        child_regs = task_pt_regs(child);
        bspstore = (unsigned long *) child_regs->ar_bspstore;
        krbs = (unsigned long *) child + IA64_RBS_OFFSET/8;
        if (on_kernel_rbs(addr, (unsigned long) bspstore,
                          (unsigned long) urbs_end))
        {
                /*
                 * Attempt to write the RBS in an area that's actually
                 * on the kernel RBS => write the corresponding bits
                 * in the kernel RBS.
                 */
                if (ia64_rse_is_rnat_slot(laddr))
                        put_rnat(child, child_stack, krbs, laddr, val,
                                 urbs_end);
                else {
                        if (laddr < urbs_end) {
                                regnum = ia64_rse_num_regs(bspstore, laddr);
                                *ia64_rse_skip_regs(krbs, regnum) = val;
                        }
                }
        } else if (access_process_vm(child, addr, &val, sizeof(val), 1)
                   != sizeof(val))
                return -EIO;
        return 0;
}

/*
 * Calculate the address of the end of the user-level register backing
 * store.  This is the address that would have been stored in ar.bsp
 * if the user had executed a "cover" instruction right before
 * entering the kernel.  If CFMP is not NULL, it is used to return the
 * "current frame mask" that was active at the time the kernel was
 * entered.
 */
unsigned long
ia64_get_user_rbs_end (struct task_struct *child, struct pt_regs *pt,
                       unsigned long *cfmp)
{
        unsigned long *krbs, *bspstore, cfm = pt->cr_ifs;
        long ndirty;

        krbs = (unsigned long *) child + IA64_RBS_OFFSET/8;
        bspstore = (unsigned long *) pt->ar_bspstore;
        ndirty = ia64_rse_num_regs(krbs, krbs + (pt->loadrs >> 19));

        if (in_syscall(pt))
                ndirty += (cfm & 0x7f);
        else
                cfm &= ~(1UL << 63);    /* clear valid bit */

        if (cfmp)
                *cfmp = cfm;
        return (unsigned long) ia64_rse_skip_regs(bspstore, ndirty);
}

/*
 * Synchronize (i.e, write) the RSE backing store living in kernel
 * space to the VM of the CHILD task.  SW and PT are the pointers to
 * the switch_stack and pt_regs structures, respectively.
 * USER_RBS_END is the user-level address at which the backing store
 * ends.
 */
long
ia64_sync_user_rbs (struct task_struct *child, struct switch_stack *sw,
                    unsigned long user_rbs_start, unsigned long user_rbs_end)
{
        unsigned long addr, val;
        long ret;

        /* now copy word for word from kernel rbs to user rbs: */
        for (addr = user_rbs_start; addr < user_rbs_end; addr += 8) {
                ret = ia64_peek(child, sw, user_rbs_end, addr, &val);
                if (ret < 0)
                        return ret;
                if (access_process_vm(child, addr, &val, sizeof(val), 1)
                    != sizeof(val))
                        return -EIO;
        }
        return 0;
}

static long
ia64_sync_kernel_rbs (struct task_struct *child, struct switch_stack *sw,
                unsigned long user_rbs_start, unsigned long user_rbs_end)
{
        unsigned long addr, val;
        long ret;

        /* now copy word for word from user rbs to kernel rbs: */
        for (addr = user_rbs_start; addr < user_rbs_end; addr += 8) {
                if (access_process_vm(child, addr, &val, sizeof(val), 0)
                                != sizeof(val))
                        return -EIO;

                ret = ia64_poke(child, sw, user_rbs_end, addr, val);
                if (ret < 0)
                        return ret;
        }
        return 0;
}

typedef long (*syncfunc_t)(struct task_struct *, struct switch_stack *,
                            unsigned long, unsigned long);

static void do_sync_rbs(struct unw_frame_info *info, void *arg)
{
        struct pt_regs *pt;
        unsigned long urbs_end;
        syncfunc_t fn = arg;

        if (unw_unwind_to_user(info) < 0)
                return;
        pt = task_pt_regs(info->task);
        urbs_end = ia64_get_user_rbs_end(info->task, pt, NULL);

        fn(info->task, info->sw, pt->ar_bspstore, urbs_end);
}

/*
 * when a thread is stopped (ptraced), debugger might change thread's user
 * stack (change memory directly), and we must avoid the RSE stored in kernel
 * to override user stack (user space's RSE is newer than kernel's in the
 * case). To workaround the issue, we copy kernel RSE to user RSE before the
 * task is stopped, so user RSE has updated data.  we then copy user RSE to
 * kernel after the task is resummed from traced stop and kernel will use the
 * newer RSE to return to user. TIF_RESTORE_RSE is the flag to indicate we need
 * synchronize user RSE to kernel.
 */
void ia64_ptrace_stop(void)
{
        if (test_and_set_tsk_thread_flag(current, TIF_RESTORE_RSE))
                return;
        set_notify_resume(current);
        unw_init_running(do_sync_rbs, ia64_sync_user_rbs);
}

/*
 * This is called to read back the register backing store.
 */
void ia64_sync_krbs(void)
{
        clear_tsk_thread_flag(current, TIF_RESTORE_RSE);

        unw_init_running(do_sync_rbs, ia64_sync_kernel_rbs);
}

/*
 * After PTRACE_ATTACH, a thread's register backing store area in user
 * space is assumed to contain correct data whenever the thread is
 * stopped.  arch_ptrace_stop takes care of this on tracing stops.
 * But if the child was already stopped for job control when we attach
 * to it, then it might not ever get into ptrace_stop by the time we
 * want to examine the user memory containing the RBS.
 */
void
ptrace_attach_sync_user_rbs (struct task_struct *child)
{
        int stopped = 0;
        struct unw_frame_info info;

        /*
         * If the child is in TASK_STOPPED, we need to change that to
         * TASK_TRACED momentarily while we operate on it.  This ensures
         * that the child won't be woken up and return to user mode while
         * we are doing the sync.  (It can only be woken up for SIGKILL.)
         */

        read_lock(&tasklist_lock);
        if (child->sighand) {
                spin_lock_irq(&child->sighand->siglock);
                if (child->state == TASK_STOPPED &&
                    !test_and_set_tsk_thread_flag(child, TIF_RESTORE_RSE)) {
                        set_notify_resume(child);

                        child->state = TASK_TRACED;
                        stopped = 1;
                }
                spin_unlock_irq(&child->sighand->siglock);
        }
        read_unlock(&tasklist_lock);

        if (!stopped)
                return;

        unw_init_from_blocked_task(&info, child);
        do_sync_rbs(&info, ia64_sync_user_rbs);

        /*
         * Now move the child back into TASK_STOPPED if it should be in a
         * job control stop, so that SIGCONT can be used to wake it up.
         */
        read_lock(&tasklist_lock);
        if (child->sighand) {
                spin_lock_irq(&child->sighand->siglock);
                if (child->state == TASK_TRACED &&
                    (child->signal->flags & SIGNAL_STOP_STOPPED)) {
                        child->state = TASK_STOPPED;
                }
                spin_unlock_irq(&child->sighand->siglock);
        }
        read_unlock(&tasklist_lock);
}

static inline int
thread_matches (struct task_struct *thread, unsigned long addr)
{
        unsigned long thread_rbs_end;
        struct pt_regs *thread_regs;

        if (ptrace_check_attach(thread, 0) < 0)
                /*
                 * If the thread is not in an attachable state, we'll
                 * ignore it.  The net effect is that if ADDR happens
                 * to overlap with the portion of the thread's
                 * register backing store that is currently residing
                 * on the thread's kernel stack, then ptrace() may end
                 * up accessing a stale value.  But if the thread
                 * isn't stopped, that's a problem anyhow, so we're
                 * doing as well as we can...
                 */
                return 0;

        thread_regs = task_pt_regs(thread);
        thread_rbs_end = ia64_get_user_rbs_end(thread, thread_regs, NULL);
        if (!on_kernel_rbs(addr, thread_regs->ar_bspstore, thread_rbs_end))
                return 0;

        return 1;       /* looks like we've got a winner */
}

/*
 * Write f32-f127 back to task->thread.fph if it has been modified.
 */
inline void
ia64_flush_fph (struct task_struct *task)
{
        struct ia64_psr *psr = ia64_psr(task_pt_regs(task));

        /*
         * Prevent migrating this task while
         * we're fiddling with the FPU state
         */
        preempt_disable();
        if (ia64_is_local_fpu_owner(task) && psr->mfh) {
                psr->mfh = 0;
                task->thread.flags |= IA64_THREAD_FPH_VALID;
                ia64_save_fpu(&task->thread.fph[0]);
        }
        preempt_enable();
}

/*
 * Sync the fph state of the task so that it can be manipulated
 * through thread.fph.  If necessary, f32-f127 are written back to
 * thread.fph or, if the fph state hasn't been used before, thread.fph
 * is cleared to zeroes.  Also, access to f32-f127 is disabled to
 * ensure that the task picks up the state from thread.fph when it
 * executes again.
 */
void
ia64_sync_fph (struct task_struct *task)
{
        struct ia64_psr *psr = ia64_psr(task_pt_regs(task));

        ia64_flush_fph(task);
        if (!(task->thread.flags & IA64_THREAD_FPH_VALID)) {
                task->thread.flags |= IA64_THREAD_FPH_VALID;
                memset(&task->thread.fph, 0, sizeof(task->thread.fph));
        }
        ia64_drop_fpu(task);
        psr->dfh = 1;
}

/*
 * Change the machine-state of CHILD such that it will return via the normal
 * kernel exit-path, rather than the syscall-exit path.
 */
static void
convert_to_non_syscall (struct task_struct *child, struct pt_regs  *pt,
                        unsigned long cfm)
{
        struct unw_frame_info info, prev_info;
        unsigned long ip, sp, pr;

        unw_init_from_blocked_task(&info, child);
        while (1) {
                prev_info = info;
                if (unw_unwind(&info) < 0)
                        return;

                unw_get_sp(&info, &sp);
                if ((long)((unsigned long)child + IA64_STK_OFFSET - sp)
                    < IA64_PT_REGS_SIZE) {
                        dprintk("ptrace.%s: ran off the top of the kernel "
                                "stack\n", __func__);
                        return;
                }
                if (unw_get_pr (&prev_info, &pr) < 0) {
                        unw_get_rp(&prev_info, &ip);
                        dprintk("ptrace.%s: failed to read "
                                "predicate register (ip=0x%lx)\n",
                                __func__, ip);
                        return;
                }
                if (unw_is_intr_frame(&info)
                    && (pr & (1UL << PRED_USER_STACK)))
                        break;
        }

        /*
         * Note: at the time of this call, the target task is blocked
         * in notify_resume_user() and by clearling PRED_LEAVE_SYSCALL
         * (aka, "pLvSys") we redirect execution from
         * .work_pending_syscall_end to .work_processed_kernel.
         */
        unw_get_pr(&prev_info, &pr);
        pr &= ~((1UL << PRED_SYSCALL) | (1UL << PRED_LEAVE_SYSCALL));
        pr |=  (1UL << PRED_NON_SYSCALL);
        unw_set_pr(&prev_info, pr);

        pt->cr_ifs = (1UL << 63) | cfm;
        /*
         * Clear the memory that is NOT written on syscall-entry to
         * ensure we do not leak kernel-state to user when execution
         * resumes.
         */
        pt->r2 = 0;
        pt->r3 = 0;
        pt->r14 = 0;
        memset(&pt->r16, 0, 16*8);      /* clear r16-r31 */
        memset(&pt->f6, 0, 6*16);       /* clear f6-f11 */
        pt->b7 = 0;
        pt->ar_ccv = 0;
        pt->ar_csd = 0;
        pt->ar_ssd = 0;
}

static int
access_nat_bits (struct task_struct *child, struct pt_regs *pt,
                 struct unw_frame_info *info,
                 unsigned long *data, int write_access)
{
        unsigned long regnum, nat_bits, scratch_unat, dummy = 0;
        char nat = 0;

        if (write_access) {
                nat_bits = *data;
                scratch_unat = ia64_put_scratch_nat_bits(pt, nat_bits);
                if (unw_set_ar(info, UNW_AR_UNAT, scratch_unat) < 0) {
                        dprintk("ptrace: failed to set ar.unat\n");
                        return -1;
                }
                for (regnum = 4; regnum <= 7; ++regnum) {
                        unw_get_gr(info, regnum, &dummy, &nat);
                        unw_set_gr(info, regnum, dummy,
                                   (nat_bits >> regnum) & 1);
                }
        } else {
                if (unw_get_ar(info, UNW_AR_UNAT, &scratch_unat) < 0) {
                        dprintk("ptrace: failed to read ar.unat\n");
                        return -1;
                }
                nat_bits = ia64_get_scratch_nat_bits(pt, scratch_unat);
                for (regnum = 4; regnum <= 7; ++regnum) {
                        unw_get_gr(info, regnum, &dummy, &nat);
                        nat_bits |= (nat != 0) << regnum;
                }
                *data = nat_bits;
        }
        return 0;
}

static int
access_uarea (struct task_struct *child, unsigned long addr,
              unsigned long *data, int write_access);

static long
ptrace_getregs (struct task_struct *child, struct pt_all_user_regs __user *ppr)
{
        unsigned long psr, ec, lc, rnat, bsp, cfm, nat_bits, val;
        struct unw_frame_info info;
        struct ia64_fpreg fpval;
        struct switch_stack *sw;
        struct pt_regs *pt;
        long ret, retval = 0;
        char nat = 0;
        int i;

        if (!access_ok(VERIFY_WRITE, ppr, sizeof(struct pt_all_user_regs)))
                return -EIO;

        pt = task_pt_regs(child);
        sw = (struct switch_stack *) (child->thread.ksp + 16);
        unw_init_from_blocked_task(&info, child);
        if (unw_unwind_to_user(&info) < 0) {
                return -EIO;
        }

        if (((unsigned long) ppr & 0x7) != 0) {
                dprintk("ptrace:unaligned register address %p\n", ppr);
                return -EIO;
        }

        if (access_uarea(child, PT_CR_IPSR, &psr, 0) < 0
            || access_uarea(child, PT_AR_EC, &ec, 0) < 0
            || access_uarea(child, PT_AR_LC, &lc, 0) < 0
            || access_uarea(child, PT_AR_RNAT, &rnat, 0) < 0
            || access_uarea(child, PT_AR_BSP, &bsp, 0) < 0
            || access_uarea(child, PT_CFM, &cfm, 0)
            || access_uarea(child, PT_NAT_BITS, &nat_bits, 0))
                return -EIO;

        /* control regs */

        retval |= __put_user(pt->cr_iip, &ppr->cr_iip);
        retval |= __put_user(psr, &ppr->cr_ipsr);

        /* app regs */

        retval |= __put_user(pt->ar_pfs, &ppr->ar[PT_AUR_PFS]);
        retval |= __put_user(pt->ar_rsc, &ppr->ar[PT_AUR_RSC]);
        retval |= __put_user(pt->ar_bspstore, &ppr->ar[PT_AUR_BSPSTORE]);
        retval |= __put_user(pt->ar_unat, &ppr->ar[PT_AUR_UNAT]);
        retval |= __put_user(pt->ar_ccv, &ppr->ar[PT_AUR_CCV]);
        retval |= __put_user(pt->ar_fpsr, &ppr->ar[PT_AUR_FPSR]);

        retval |= __put_user(ec, &ppr->ar[PT_AUR_EC]);
        retval |= __put_user(lc, &ppr->ar[PT_AUR_LC]);
        retval |= __put_user(rnat, &ppr->ar[PT_AUR_RNAT]);
        retval |= __put_user(bsp, &ppr->ar[PT_AUR_BSP]);
        retval |= __put_user(cfm, &ppr->cfm);

        /* gr1-gr3 */

        retval |= __copy_to_user(&ppr->gr[1], &pt->r1, sizeof(long));
        retval |= __copy_to_user(&ppr->gr[2], &pt->r2, sizeof(long) *2);

        /* gr4-gr7 */

        for (i = 4; i < 8; i++) {
                if (unw_access_gr(&info, i, &val, &nat, 0) < 0)
                        return -EIO;
                retval |= __put_user(val, &ppr->gr[i]);
        }

        /* gr8-gr11 */

        retval |= __copy_to_user(&ppr->gr[8], &pt->r8, sizeof(long) * 4);

        /* gr12-gr15 */

        retval |= __copy_to_user(&ppr->gr[12], &pt->r12, sizeof(long) * 2);
        retval |= __copy_to_user(&ppr->gr[14], &pt->r14, sizeof(long));
        retval |= __copy_to_user(&ppr->gr[15], &pt->r15, sizeof(long));

        /* gr16-gr31 */

        retval |= __copy_to_user(&ppr->gr[16], &pt->r16, sizeof(long) * 16);

        /* b0 */

        retval |= __put_user(pt->b0, &ppr->br[0]);

        /* b1-b5 */

        for (i = 1; i < 6; i++) {
                if (unw_access_br(&info, i, &val, 0) < 0)
                        return -EIO;
                __put_user(val, &ppr->br[i]);
        }

        /* b6-b7 */

        retval |= __put_user(pt->b6, &ppr->br[6]);
        retval |= __put_user(pt->b7, &ppr->br[7]);

        /* fr2-fr5 */

        for (i = 2; i < 6; i++) {
                if (unw_get_fr(&info, i, &fpval) < 0)
                        return -EIO;
                retval |= __copy_to_user(&ppr->fr[i], &fpval, sizeof (fpval));
        }

        /* fr6-fr11 */

        retval |= __copy_to_user(&ppr->fr[6], &pt->f6,
                                 sizeof(struct ia64_fpreg) * 6);

        /* fp scratch regs(12-15) */

        retval |= __copy_to_user(&ppr->fr[12], &sw->f12,
                                 sizeof(struct ia64_fpreg) * 4);

        /* fr16-fr31 */

        for (i = 16; i < 32; i++) {
                if (unw_get_fr(&info, i, &fpval) < 0)
                        return -EIO;
                retval |= __copy_to_user(&ppr->fr[i], &fpval, sizeof (fpval));
        }

        /* fph */

        ia64_flush_fph(child);
        retval |= __copy_to_user(&ppr->fr[32], &child->thread.fph,
                                 sizeof(ppr->fr[32]) * 96);

        /*  preds */

        retval |= __put_user(pt->pr, &ppr->pr);

        /* nat bits */

        retval |= __put_user(nat_bits, &ppr->nat);

        ret = retval ? -EIO : 0;
        return ret;
}

static long
ptrace_setregs (struct task_struct *child, struct pt_all_user_regs __user *ppr)
{
        unsigned long psr, rsc, ec, lc, rnat, bsp, cfm, nat_bits, val = 0;
        struct unw_frame_info info;
        struct switch_stack *sw;
        struct ia64_fpreg fpval;
        struct pt_regs *pt;
        long ret, retval = 0;
        int i;

        memset(&fpval, 0, sizeof(fpval));

        if (!access_ok(VERIFY_READ, ppr, sizeof(struct pt_all_user_regs)))
                return -EIO;

        pt = task_pt_regs(child);
        sw = (struct switch_stack *) (child->thread.ksp + 16);
        unw_init_from_blocked_task(&info, child);
        if (unw_unwind_to_user(&info) < 0) {
                return -EIO;
        }

        if (((unsigned long) ppr & 0x7) != 0) {
                dprintk("ptrace:unaligned register address %p\n", ppr);
                return -EIO;
        }

        /* control regs */

        retval |= __get_user(pt->cr_iip, &ppr->cr_iip);
        retval |= __get_user(psr, &ppr->cr_ipsr);

        /* app regs */

        retval |= __get_user(pt->ar_pfs, &ppr->ar[PT_AUR_PFS]);
        retval |= __get_user(rsc, &ppr->ar[PT_AUR_RSC]);
        retval |= __get_user(pt->ar_bspstore, &ppr->ar[PT_AUR_BSPSTORE]);
        retval |= __get_user(pt->ar_unat, &ppr->ar[PT_AUR_UNAT]);
        retval |= __get_user(pt->ar_ccv, &ppr->ar[PT_AUR_CCV]);
        retval |= __get_user(pt->ar_fpsr, &ppr->ar[PT_AUR_FPSR]);

        retval |= __get_user(ec, &ppr->ar[PT_AUR_EC]);
        retval |= __get_user(lc, &ppr->ar[PT_AUR_LC]);
        retval |= __get_user(rnat, &ppr->ar[PT_AUR_RNAT]);
        retval |= __get_user(bsp, &ppr->ar[PT_AUR_BSP]);
        retval |= __get_user(cfm, &ppr->cfm);

        /* gr1-gr3 */

        retval |= __copy_from_user(&pt->r1, &ppr->gr[1], sizeof(long));
        retval |= __copy_from_user(&pt->r2, &ppr->gr[2], sizeof(long) * 2);

        /* gr4-gr7 */

        for (i = 4; i < 8; i++) {
                retval |= __get_user(val, &ppr->gr[i]);
                /* NaT bit will be set via PT_NAT_BITS: */
                if (unw_set_gr(&info, i, val, 0) < 0)
                        return -EIO;
        }

        /* gr8-gr11 */

        retval |= __copy_from_user(&pt->r8, &ppr->gr[8], sizeof(long) * 4);

        /* gr12-gr15 */

        retval |= __copy_from_user(&pt->r12, &ppr->gr[12], sizeof(long) * 2);
        retval |= __copy_from_user(&pt->r14, &ppr->gr[14], sizeof(long));
        retval |= __copy_from_user(&pt->r15, &ppr->gr[15], sizeof(long));

        /* gr16-gr31 */

        retval |= __copy_from_user(&pt->r16, &ppr->gr[16], sizeof(long) * 16);

        /* b0 */

        retval |= __get_user(pt->b0, &ppr->br[0]);

        /* b1-b5 */

        for (i = 1; i < 6; i++) {
                retval |= __get_user(val, &ppr->br[i]);
                unw_set_br(&info, i, val);
        }

        /* b6-b7 */

        retval |= __get_user(pt->b6, &ppr->br[6]);
        retval |= __get_user(pt->b7, &ppr->br[7]);

        /* fr2-fr5 */

        for (i = 2; i < 6; i++) {
                retval |= __copy_from_user(&fpval, &ppr->fr[i], sizeof(fpval));
                if (unw_set_fr(&info, i, fpval) < 0)
                        return -EIO;
        }

        /* fr6-fr11 */

        retval |= __copy_from_user(&pt->f6, &ppr->fr[6],
                                   sizeof(ppr->fr[6]) * 6);

        /* fp scratch regs(12-15) */

        retval |= __copy_from_user(&sw->f12, &ppr->fr[12],
                                   sizeof(ppr->fr[12]) * 4);

        /* fr16-fr31 */

        for (i = 16; i < 32; i++) {
                retval |= __copy_from_user(&fpval, &ppr->fr[i],
                                           sizeof(fpval));
                if (unw_set_fr(&info, i, fpval) < 0)
                        return -EIO;
        }

        /* fph */

        ia64_sync_fph(child);
        retval |= __copy_from_user(&child->thread.fph, &ppr->fr[32],
                                   sizeof(ppr->fr[32]) * 96);

        /* preds */

        retval |= __get_user(pt->pr, &ppr->pr);

        /* nat bits */

        retval |= __get_user(nat_bits, &ppr->nat);

        retval |= access_uarea(child, PT_CR_IPSR, &psr, 1);
        retval |= access_uarea(child, PT_AR_RSC, &rsc, 1);
        retval |= access_uarea(child, PT_AR_EC, &ec, 1);
        retval |= access_uarea(child, PT_AR_LC, &lc, 1);
        retval |= access_uarea(child, PT_AR_RNAT, &rnat, 1);
        retval |= access_uarea(child, PT_AR_BSP, &bsp, 1);
        retval |= access_uarea(child, PT_CFM, &cfm, 1);
        retval |= access_uarea(child, PT_NAT_BITS, &nat_bits, 1);

        ret = retval ? -EIO : 0;
        return ret;
}

void
user_enable_single_step (struct task_struct *child)
{
        struct ia64_psr *child_psr = ia64_psr(task_pt_regs(child));

        set_tsk_thread_flag(child, TIF_SINGLESTEP);
        child_psr->ss = 1;
}

void
user_enable_block_step (struct task_struct *child)
{
        struct ia64_psr *child_psr = ia64_psr(task_pt_regs(child));

        set_tsk_thread_flag(child, TIF_SINGLESTEP);
        child_psr->tb = 1;
}

void
user_disable_single_step (struct task_struct *child)
{
        struct ia64_psr *child_psr = ia64_psr(task_pt_regs(child));

        /* make sure the single step/taken-branch trap bits are not set: */
        clear_tsk_thread_flag(child, TIF_SINGLESTEP);
        child_psr->ss = 0;
        child_psr->tb = 0;
}

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure the single step bit is not set.
 */
void
ptrace_disable (struct task_struct *child)
{
        user_disable_single_step(child);
}

long
arch_ptrace (struct task_struct *child, long request,
             unsigned long addr, unsigned long data)
{
        switch (request) {
        case PTRACE_PEEKTEXT:
        case PTRACE_PEEKDATA:
                /* read word at location addr */
                if (access_process_vm(child, addr, &data, sizeof(data), 0)
                    != sizeof(data))
                        return -EIO;
                /* ensure return value is not mistaken for error code */
                force_successful_syscall_return();
                return data;

        /* PTRACE_POKETEXT and PTRACE_POKEDATA is handled
         * by the generic ptrace_request().
         */

        case PTRACE_PEEKUSR:
                /* read the word at addr in the USER area */
                if (access_uarea(child, addr, &data, 0) < 0)
                        return -EIO;
                /* ensure return value is not mistaken for error code */
                force_successful_syscall_return();
                return data;

        case PTRACE_POKEUSR:
                /* write the word at addr in the USER area */
                if (access_uarea(child, addr, &data, 1) < 0)
                        return -EIO;
                return 0;

        case PTRACE_OLD_GETSIGINFO:
                /* for backwards-compatibility */
                return ptrace_request(child, PTRACE_GETSIGINFO, addr, data);

        case PTRACE_OLD_SETSIGINFO:
                /* for backwards-compatibility */
                return ptrace_request(child, PTRACE_SETSIGINFO, addr, data);

        case PTRACE_GETREGS:
                return ptrace_getregs(child,
                                      (struct pt_all_user_regs __user *) data);

        case PTRACE_SETREGS:
                return ptrace_setregs(child,
                                      (struct pt_all_user_regs __user *) data);

        default:
                return ptrace_request(child, request, addr, data);
        }
}


/* "asmlinkage" so the input arguments are preserved... */

asmlinkage long
syscall_trace_enter (long arg0, long arg1, long arg2, long arg3,
                     long arg4, long arg5, long arg6, long arg7,
                     struct pt_regs regs)
{
        if (test_thread_flag(TIF_SYSCALL_TRACE))
                if (tracehook_report_syscall_entry(&regs))
                        return -ENOSYS;

        /* copy user rbs to kernel rbs */
        if (test_thread_flag(TIF_RESTORE_RSE))
                ia64_sync_krbs();

        if (unlikely(current->audit_context)) {
                long syscall;
                int arch;

                syscall = regs.r15;
                arch = AUDIT_ARCH_IA64;

                audit_syscall_entry(arch, syscall, arg0, arg1, arg2, arg3);
        }

        return 0;
}

/* "asmlinkage" so the input arguments are preserved... */

asmlinkage void
syscall_trace_leave (long arg0, long arg1, long arg2, long arg3,
                     long arg4, long arg5, long arg6, long arg7,
                     struct pt_regs regs)
{
        int step;

        if (unlikely(current->audit_context)) {
                int success = AUDITSC_RESULT(regs.r10);
                long result = regs.r8;

                if (success != AUDITSC_SUCCESS)
                        result = -result;
                audit_syscall_exit(success, result);
        }

        step = test_thread_flag(TIF_SINGLESTEP);
        if (step || test_thread_flag(TIF_SYSCALL_TRACE))
                tracehook_report_syscall_exit(&regs, step);

        /* copy user rbs to kernel rbs */
        if (test_thread_flag(TIF_RESTORE_RSE))
                ia64_sync_krbs();
}

/* Utrace implementation starts here */
struct regset_get {
        void *kbuf;
        void __user *ubuf;
};

struct regset_set {
        const void *kbuf;
        const void __user *ubuf;
};

struct regset_getset {
        struct task_struct *target;
        const struct user_regset *regset;
        union {
                struct regset_get get;
                struct regset_set set;
        } u;
        unsigned int pos;
        unsigned int count;
        int ret;
};

static int
access_elf_gpreg(struct task_struct *target, struct unw_frame_info *info,
                unsigned long addr, unsigned long *data, int write_access)
{
        struct pt_regs *pt;
        unsigned long *ptr = NULL;
        int ret;
        char nat = 0;

        pt = task_pt_regs(target);
        switch (addr) {
        case ELF_GR_OFFSET(1):
                ptr = &pt->r1;
                break;
        case ELF_GR_OFFSET(2):
        case ELF_GR_OFFSET(3):
                ptr = (void *)&pt->r2 + (addr - ELF_GR_OFFSET(2));
                break;
        case ELF_GR_OFFSET(4) ... ELF_GR_OFFSET(7):
                if (write_access) {
                        /* read NaT bit first: */
                        unsigned long dummy;

                        ret = unw_get_gr(info, addr/8, &dummy, &nat);
                        if (ret < 0)
                                return ret;
                }
                return unw_access_gr(info, addr/8, data, &nat, write_access);
        case ELF_GR_OFFSET(8) ... ELF_GR_OFFSET(11):
                ptr = (void *)&pt->r8 + addr - ELF_GR_OFFSET(8);
                break;
        case ELF_GR_OFFSET(12):
        case ELF_GR_OFFSET(13):
                ptr = (void *)&pt->r12 + addr - ELF_GR_OFFSET(12);
                break;
        case ELF_GR_OFFSET(14):
                ptr = &pt->r14;
                break;
        case ELF_GR_OFFSET(15):
                ptr = &pt->r15;
        }
        if (write_access)
                *ptr = *data;
        else
                *data = *ptr;
        return 0;
}

static int
access_elf_breg(struct task_struct *target, struct unw_frame_info *info,
                unsigned long addr, unsigned long *data, int write_access)
{
        struct pt_regs *pt;
        unsigned long *ptr = NULL;

        pt = task_pt_regs(target);
        switch (addr) {
        case ELF_BR_OFFSET(0):
                ptr = &pt->b0;
                break;
        case ELF_BR_OFFSET(1) ... ELF_BR_OFFSET(5):
                return unw_access_br(info, (addr - ELF_BR_OFFSET(0))/8,
                                     data, write_access);
        case ELF_BR_OFFSET(6):
                ptr = &pt->b6;
                break;
        case ELF_BR_OFFSET(7):
                ptr = &pt->b7;
        }
        if (write_access)
                *ptr = *data;
        else
                *data = *ptr;
        return 0;
}

static int
access_elf_areg(struct task_struct *target, struct unw_frame_info *info,
                unsigned long addr, unsigned long *data, int write_access)
{
        struct pt_regs *pt;
        unsigned long cfm, urbs_end;
        unsigned long *ptr = NULL;

        pt = task_pt_regs(target);
        if (addr >= ELF_AR_RSC_OFFSET && addr <= ELF_AR_SSD_OFFSET) {
                switch (addr) {
                case ELF_AR_RSC_OFFSET:
                        /* force PL3 */
                        if (write_access)
                                pt->ar_rsc = *data | (3 << 2);
                        else
                                *data = pt->ar_rsc;
                        return 0;
                case ELF_AR_BSP_OFFSET:
                        /*
                         * By convention, we use PT_AR_BSP to refer to
                         * the end of the user-level backing store.
                         * Use ia64_rse_skip_regs(PT_AR_BSP, -CFM.sof)
                         * to get the real value of ar.bsp at the time
                         * the kernel was entered.
                         *
                         * Furthermore, when changing the contents of
                         * PT_AR_BSP (or PT_CFM) while the task is
                         * blocked in a system call, convert the state
                         * so that the non-system-call exit
                         * path is used.  This ensures that the proper
                         * state will be picked up when resuming
                         * execution.  However, it *also* means that
                         * once we write PT_AR_BSP/PT_CFM, it won't be
                         * possible to modify the syscall arguments of
                         * the pending system call any longer.  This
                         * shouldn't be an issue because modifying
                         * PT_AR_BSP/PT_CFM generally implies that
                         * we're either abandoning the pending system
                         * call or that we defer it's re-execution
                         * (e.g., due to GDB doing an inferior
                         * function call).
                         */
                        urbs_end = ia64_get_user_rbs_end(target, pt, &cfm);
                        if (write_access) {
                                if (*data != urbs_end) {
                                        if (in_syscall(pt))
                                                convert_to_non_syscall(target,
                                                                       pt,
                                                                       cfm);
                                        /*
                                         * Simulate user-level write
                                         * of ar.bsp:
                                         */
                                        pt->loadrs = 0;
                                        pt->ar_bspstore = *data;
                                }
                        } else
                                *data = urbs_end;
                        return 0;
                case ELF_AR_BSPSTORE_OFFSET:
                        ptr = &pt->ar_bspstore;
                        break;
                case ELF_AR_RNAT_OFFSET:
                        ptr = &pt->ar_rnat;
                        break;
                case ELF_AR_CCV_OFFSET:
                        ptr = &pt->ar_ccv;
                        break;
                case ELF_AR_UNAT_OFFSET:
                        ptr = &pt->ar_unat;
                        break;
                case ELF_AR_FPSR_OFFSET:
                        ptr = &pt->ar_fpsr;
                        break;
                case ELF_AR_PFS_OFFSET:
                        ptr = &pt->ar_pfs;
                        break;
                case ELF_AR_LC_OFFSET:
                        return unw_access_ar(info, UNW_AR_LC, data,
                                             write_access);
                case ELF_AR_EC_OFFSET:
                        return unw_access_ar(info, UNW_AR_EC, data,
                                             write_access);
                case ELF_AR_CSD_OFFSET:
                        ptr = &pt->ar_csd;
                        break;
                case ELF_AR_SSD_OFFSET:
                        ptr = &pt->ar_ssd;
                }
        } else if (addr >= ELF_CR_IIP_OFFSET && addr <= ELF_CR_IPSR_OFFSET) {
                switch (addr) {
                case ELF_CR_IIP_OFFSET:
                        ptr = &pt->cr_iip;
                        break;
                case ELF_CFM_OFFSET:
                        urbs_end = ia64_get_user_rbs_end(target, pt, &cfm);
                        if (write_access) {
                                if (((cfm ^ *data) & PFM_MASK) != 0) {
                                        if (in_syscall(pt))
                                                convert_to_non_syscall(target,
                                                                       pt,
                                                                       cfm);
                                        pt->cr_ifs = ((pt->cr_ifs & ~PFM_MASK)
                                                      | (*data & PFM_MASK));
                                }
                        } else
                                *data = cfm;
                        return 0;
                case ELF_CR_IPSR_OFFSET:
                        if (write_access) {
                                unsigned long tmp = *data;
                                /* psr.ri==3 is a reserved value: SDM 2:25 */
                                if ((tmp & IA64_PSR_RI) == IA64_PSR_RI)
                                        tmp &= ~IA64_PSR_RI;
                                pt->cr_ipsr = ((tmp & IPSR_MASK)
                                               | (pt->cr_ipsr & ~IPSR_MASK));
                        } else
                                *data = (pt->cr_ipsr & IPSR_MASK);
                        return 0;
                }
        } else if (addr == ELF_NAT_OFFSET)
                return access_nat_bits(target, pt, info,
                                       data, write_access);
        else if (addr == ELF_PR_OFFSET)
                ptr = &pt->pr;
        else
                return -1;

        if (write_access)
                *ptr = *data;
        else
                *data = *ptr;

        return 0;
}

static int
access_elf_reg(struct task_struct *target, struct unw_frame_info *info,
                unsigned long addr, unsigned long *data, int write_access)
{
        if (addr >= ELF_GR_OFFSET(1) && addr <= ELF_GR_OFFSET(15))
                return access_elf_gpreg(target, info, addr, data, write_access);
        else if (addr >= ELF_BR_OFFSET(0) && addr <= ELF_BR_OFFSET(7))
                return access_elf_breg(target, info, addr, data, write_access);
        else
                return access_elf_areg(target, info, addr, data, write_access);
}

void do_gpregs_get(struct unw_frame_info *info, void *arg)
{
        struct pt_regs *pt;
        struct regset_getset *dst = arg;
        elf_greg_t tmp[16];
        unsigned int i, index, min_copy;

        if (unw_unwind_to_user(info) < 0)
                return;

        /*
         * coredump format:
         *      r0-r31
         *      NaT bits (for r0-r31; bit N == 1 iff rN is a NaT)
         *      predicate registers (p0-p63)
         *      b0-b7
         *      ip cfm user-mask
         *      ar.rsc ar.bsp ar.bspstore ar.rnat
         *      ar.ccv ar.unat ar.fpsr ar.pfs ar.lc ar.ec
         */


        /* Skip r0 */
        if (dst->count > 0 && dst->pos < ELF_GR_OFFSET(1)) {
                dst->ret = user_regset_copyout_zero(&dst->pos, &dst->count,
                                                      &dst->u.get.kbuf,
                                                      &dst->u.get.ubuf,
                                                      0, ELF_GR_OFFSET(1));
                if (dst->ret || dst->count == 0)
                        return;
        }

        /* gr1 - gr15 */
        if (dst->count > 0 && dst->pos < ELF_GR_OFFSET(16)) {
                index = (dst->pos - ELF_GR_OFFSET(1)) / sizeof(elf_greg_t);
                min_copy = ELF_GR_OFFSET(16) > (dst->pos + dst->count) ?
                         (dst->pos + dst->count) : ELF_GR_OFFSET(16);
                for (i = dst->pos; i < min_copy; i += sizeof(elf_greg_t),
                                index++)
                        if (access_elf_reg(dst->target, info, i,
                                                &tmp[index], 0) < 0) {
                                dst->ret = -EIO;
                                return;
                        }
                dst->ret = user_regset_copyout(&dst->pos, &dst->count,
                                &dst->u.get.kbuf, &dst->u.get.ubuf, tmp,
                                ELF_GR_OFFSET(1), ELF_GR_OFFSET(16));
                if (dst->ret || dst->count == 0)
                        return;
        }

        /* r16-r31 */
        if (dst->count > 0 && dst->pos < ELF_NAT_OFFSET) {
                pt = task_pt_regs(dst->target);
                dst->ret = user_regset_copyout(&dst->pos, &dst->count,
                                &dst->u.get.kbuf, &dst->u.get.ubuf, &pt->r16,
                                ELF_GR_OFFSET(16), ELF_NAT_OFFSET);
                if (dst->ret || dst->count == 0)
                        return;
        }

        /* nat, pr, b0 - b7 */
        if (dst->count > 0 && dst->pos < ELF_CR_IIP_OFFSET) {
                index = (dst->pos - ELF_NAT_OFFSET) / sizeof(elf_greg_t);
                min_copy = ELF_CR_IIP_OFFSET > (dst->pos + dst->count) ?
                         (dst->pos + dst->count) : ELF_CR_IIP_OFFSET;
                for (i = dst->pos; i < min_copy; i += sizeof(elf_greg_t),
                                index++)
                        if (access_elf_reg(dst->target, info, i,
                                                &tmp[index], 0) < 0) {
                                dst->ret = -EIO;
                                return;
                        }
                dst->ret = user_regset_copyout(&dst->pos, &dst->count,
                                &dst->u.get.kbuf, &dst->u.get.ubuf, tmp,
                                ELF_NAT_OFFSET, ELF_CR_IIP_OFFSET);
                if (dst->ret || dst->count == 0)
                        return;
        }

        /* ip cfm psr ar.rsc ar.bsp ar.bspstore ar.rnat
         * ar.ccv ar.unat ar.fpsr ar.pfs ar.lc ar.ec ar.csd ar.ssd
         */
        if (dst->count > 0 && dst->pos < (ELF_AR_END_OFFSET)) {
                index = (dst->pos - ELF_CR_IIP_OFFSET) / sizeof(elf_greg_t);
                min_copy = ELF_AR_END_OFFSET > (dst->pos + dst->count) ?
                         (dst->pos + dst->count) : ELF_AR_END_OFFSET;
                for (i = dst->pos; i < min_copy; i += sizeof(elf_greg_t),
                                index++)
                        if (access_elf_reg(dst->target, info, i,
                                                &tmp[index], 0) < 0) {
                                dst->ret = -EIO;
                                return;
                        }
                dst->ret = user_regset_copyout(&dst->pos, &dst->count,
                                &dst->u.get.kbuf, &dst->u.get.ubuf, tmp,
                                ELF_CR_IIP_OFFSET, ELF_AR_END_OFFSET);
        }
}

void do_gpregs_set(struct unw_frame_info *info, void *arg)
{
        struct pt_regs *pt;
        struct regset_getset *dst = arg;
        elf_greg_t tmp[16];
        unsigned int i, index;

        if (unw_unwind_to_user(info) < 0)
                return;

        /* Skip r0 */
        if (dst->count > 0 && dst->pos < ELF_GR_OFFSET(1)) {
                dst->ret = user_regset_copyin_ignore(&dst->pos, &dst->count,
                                                       &dst->u.set.kbuf,
                                                       &dst->u.set.ubuf,
                                                       0, ELF_GR_OFFSET(1));
                if (dst->ret || dst->count == 0)
                        return;
        }

        /* gr1-gr15 */
        if (dst->count > 0 && dst->pos < ELF_GR_OFFSET(16)) {
                i = dst->pos;
                index = (dst->pos - ELF_GR_OFFSET(1)) / sizeof(elf_greg_t);
                dst->ret = user_regset_copyin(&dst->pos, &dst->count,
                                &dst->u.set.kbuf, &dst->u.set.ubuf, tmp,
                                ELF_GR_OFFSET(1), ELF_GR_OFFSET(16));
                if (dst->ret)
                        return;
                for ( ; i < dst->pos; i += sizeof(elf_greg_t), index++)
                        if (access_elf_reg(dst->target, info, i,
                                                &tmp[index], 1) < 0) {
                                dst->ret = -EIO;
                                return;
                        }
                if (dst->count == 0)
                        return;
        }

        /* gr16-gr31 */
        if (dst->count > 0 && dst->pos < ELF_NAT_OFFSET) {
                pt = task_pt_regs(dst->target);
                dst->ret = user_regset_copyin(&dst->pos, &dst->count,
                                &dst->u.set.kbuf, &dst->u.set.ubuf, &pt->r16,
                                ELF_GR_OFFSET(16), ELF_NAT_OFFSET);
                if (dst->ret || dst->count == 0)
                        return;
        }

        /* nat, pr, b0 - b7 */
        if (dst->count > 0 && dst->pos < ELF_CR_IIP_OFFSET) {
                i = dst->pos;
                index = (dst->pos - ELF_NAT_OFFSET) / sizeof(elf_greg_t);
                dst->ret = user_regset_copyin(&dst->pos, &dst->count,
                                &dst->u.set.kbuf, &dst->u.set.ubuf, tmp,
                                ELF_NAT_OFFSET, ELF_CR_IIP_OFFSET);
                if (dst->ret)
                        return;
                for (; i < dst->pos; i += sizeof(elf_greg_t), index++)
                        if (access_elf_reg(dst->target, info, i,
                                                &tmp[index], 1) < 0) {
                                dst->ret = -EIO;
                                return;
                        }
                if (dst->count == 0)
                        return;
        }

        /* ip cfm psr ar.rsc ar.bsp ar.bspstore ar.rnat
         * ar.ccv ar.unat ar.fpsr ar.pfs ar.lc ar.ec ar.csd ar.ssd
         */
        if (dst->count > 0 && dst->pos < (ELF_AR_END_OFFSET)) {
                i = dst->pos;
                index = (dst->pos - ELF_CR_IIP_OFFSET) / sizeof(elf_greg_t);
                dst->ret = user_regset_copyin(&dst->pos, &dst->count,
                                &dst->u.set.kbuf, &dst->u.set.ubuf, tmp,
                                ELF_CR_IIP_OFFSET, ELF_AR_END_OFFSET);
                if (dst->ret)
                        return;
                for ( ; i < dst->pos; i += sizeof(elf_greg_t), index++)
                        if (access_elf_reg(dst->target, info, i,
                                                &tmp[index], 1) < 0) {
                                dst->ret = -EIO;
                                return;
                        }
        }
}

#define ELF_FP_OFFSET(i)        (i * sizeof(elf_fpreg_t))

void do_fpregs_get(struct unw_frame_info *info, void *arg)
{
        struct regset_getset *dst = arg;
        struct task_struct *task = dst->target;
        elf_fpreg_t tmp[30];
        int index, min_copy, i;

        if (unw_unwind_to_user(info) < 0)
                return;

        /* Skip pos 0 and 1 */
        if (dst->count > 0 && dst->pos < ELF_FP_OFFSET(2)) {
                dst->ret = user_regset_copyout_zero(&dst->pos, &dst->count,
                                                      &dst->u.get.kbuf,
                                                      &dst->u.get.ubuf,
                                                      0, ELF_FP_OFFSET(2));
                if (dst->count == 0 || dst->ret)
                        return;
        }

        /* fr2-fr31 */
        if (dst->count > 0 && dst->pos < ELF_FP_OFFSET(32)) {
                index = (dst->pos - ELF_FP_OFFSET(2)) / sizeof(elf_fpreg_t);

                min_copy = min(((unsigned int)ELF_FP_OFFSET(32)),
                                dst->pos + dst->count);
                for (i = dst->pos; i < min_copy; i += sizeof(elf_fpreg_t),
                                index++)
                        if (unw_get_fr(info, i / sizeof(elf_fpreg_t),
                                         &tmp[index])) {
                                dst->ret = -EIO;
                                return;
                        }
                dst->ret = user_regset_copyout(&dst->pos, &dst->count,
                                &dst->u.get.kbuf, &dst->u.get.ubuf, tmp,
                                ELF_FP_OFFSET(2), ELF_FP_OFFSET(32));
                if (dst->count == 0 || dst->ret)
                        return;
        }

        /* fph */
        if (dst->count > 0) {
                ia64_flush_fph(dst->target);
                if (task->thread.flags & IA64_THREAD_FPH_VALID)
                        dst->ret = user_regset_copyout(
                                &dst->pos, &dst->count,
                                &dst->u.get.kbuf, &dst->u.get.ubuf,
                                &dst->target->thread.fph,
                                ELF_FP_OFFSET(32), -1);
                else
                        /* Zero fill instead.  */
                        dst->ret = user_regset_copyout_zero(
                                &dst->pos, &dst->count,
                                &dst->u.get.kbuf, &dst->u.get.ubuf,
                                ELF_FP_OFFSET(32), -1);
        }
}

void do_fpregs_set(struct unw_frame_info *info, void *arg)
{
        struct regset_getset *dst = arg;
        elf_fpreg_t fpreg, tmp[30];
        int index, start, end;

        if (unw_unwind_to_user(info) < 0)
                return;

        /* Skip pos 0 and 1 */
        if (dst->count > 0 && dst->pos < ELF_FP_OFFSET(2)) {
                dst->ret = user_regset_copyin_ignore(&dst->pos, &dst->count,
                                                       &dst->u.set.kbuf,
                                                       &dst->u.set.ubuf,
                                                       0, ELF_FP_OFFSET(2));
                if (dst->count == 0 || dst->ret)
                        return;
        }

        /* fr2-fr31 */
        if (dst->count > 0 && dst->pos < ELF_FP_OFFSET(32)) {
                start = dst->pos;
                end = min(((unsigned int)ELF_FP_OFFSET(32)),
                         dst->pos + dst->count);
                dst->ret = user_regset_copyin(&dst->pos, &dst->count,
                                &dst->u.set.kbuf, &dst->u.set.ubuf, tmp,
                                ELF_FP_OFFSET(2), ELF_FP_OFFSET(32));
                if (dst->ret)
                        return;

                if (start & 0xF) { /* only write high part */
                        if (unw_get_fr(info, start / sizeof(elf_fpreg_t),
                                         &fpreg)) {
                                dst->ret = -EIO;
                                return;
                        }
                        tmp[start / sizeof(elf_fpreg_t) - 2].u.bits[0]
                                = fpreg.u.bits[0];
                        start &= ~0xFUL;
                }
                if (end & 0xF) { /* only write low part */
                        if (unw_get_fr(info, end / sizeof(elf_fpreg_t),
                                        &fpreg)) {
                                dst->ret = -EIO;
                                return;
                        }
                        tmp[end / sizeof(elf_fpreg_t) - 2].u.bits[1]
                                = fpreg.u.bits[1];
                        end = (end + 0xF) & ~0xFUL;
                }

                for ( ; start < end ; start += sizeof(elf_fpreg_t)) {
                        index = start / sizeof(elf_fpreg_t);
                        if (unw_set_fr(info, index, tmp[index - 2])) {
                                dst->ret = -EIO;
                                return;
                        }
                }
                if (dst->ret || dst->count == 0)
                        return;
        }

        /* fph */
        if (dst->count > 0 && dst->pos < ELF_FP_OFFSET(128)) {
                ia64_sync_fph(dst->target);
                dst->ret = user_regset_copyin(&dst->pos, &dst->count,
                                                &dst->u.set.kbuf,
                                                &dst->u.set.ubuf,
                                                &dst->target->thread.fph,
                                                ELF_FP_OFFSET(32), -1);
        }
}

static int
do_regset_call(void (*call)(struct unw_frame_info *, void *),
               struct task_struct *target,
               const struct user_regset *regset,
               unsigned int pos, unsigned int count,
               const void *kbuf, const void __user *ubuf)
{
        struct regset_getset info = { .target = target, .regset = regset,
                                 .pos = pos, .count = count,
                                 .u.set = { .kbuf = kbuf, .ubuf = ubuf },
                                 .ret = 0 };

        if (target == current)
                unw_init_running(call, &info);
        else {
                struct unw_frame_info ufi;
                memset(&ufi, 0, sizeof(ufi));
                unw_init_from_blocked_task(&ufi, target);
                (*call)(&ufi, &info);
        }

        return info.ret;
}

static int
gpregs_get(struct task_struct *target,
           const struct user_regset *regset,
           unsigned int pos, unsigned int count,
           void *kbuf, void __user *ubuf)
{
        return do_regset_call(do_gpregs_get, target, regset, pos, count,
                kbuf, ubuf);
}

static int gpregs_set(struct task_struct *target,
                const struct user_regset *regset,
                unsigned int pos, unsigned int count,
                const void *kbuf, const void __user *ubuf)
{
        return do_regset_call(do_gpregs_set, target, regset, pos, count,
                kbuf, ubuf);
}

static void do_gpregs_writeback(struct unw_frame_info *info, void *arg)
{
        do_sync_rbs(info, ia64_sync_user_rbs);
}

/*
 * This is called to write back the register backing store.
 * ptrace does this before it stops, so that a tracer reading the user
 * memory after the thread stops will get the current register data.
 */
static int
gpregs_writeback(struct task_struct *target,
                 const struct user_regset *regset,
                 int now)
{
        if (test_and_set_tsk_thread_flag(target, TIF_RESTORE_RSE))
                return 0;
        set_notify_resume(target);
        return do_regset_call(do_gpregs_writeback, target, regset, 0, 0,
                NULL, NULL);
}

static int
fpregs_active(struct task_struct *target, const struct user_regset *regset)
{
        return (target->thread.flags & IA64_THREAD_FPH_VALID) ? 128 : 32;
}

static int fpregs_get(struct task_struct *target,
                const struct user_regset *regset,
                unsigned int pos, unsigned int count,
                void *kbuf, void __user *ubuf)
{
        return do_regset_call(do_fpregs_get, target, regset, pos, count,
                kbuf, ubuf);
}

static int fpregs_set(struct task_struct *target,
                const struct user_regset *regset,
                unsigned int pos, unsigned int count,
                const void *kbuf, const void __user *ubuf)
{
        return do_regset_call(do_fpregs_set, target, regset, pos, count,
                kbuf, ubuf);
}

static int
access_uarea(struct task_struct *child, unsigned long addr,
              unsigned long *data, int write_access)
{
        unsigned int pos = -1; /* an invalid value */
        int ret;
        unsigned long *ptr, regnum;

        if ((addr & 0x7) != 0) {
                dprintk("ptrace: unaligned register address 0x%lx\n", addr);
                return -1;
        }
        if ((addr >= PT_NAT_BITS + 8 && addr < PT_F2) ||
                (addr >= PT_R7 + 8 && addr < PT_B1) ||
                (addr >= PT_AR_LC + 8 && addr < PT_CR_IPSR) ||
                (addr >= PT_AR_SSD + 8 && addr < PT_DBR)) {
                dprintk("ptrace: rejecting access to register "
                                        "address 0x%lx\n", addr);
                return -1;
        }

        switch (addr) {
        case PT_F32 ... (PT_F127 + 15):
                pos = addr - PT_F32 + ELF_FP_OFFSET(32);
                break;
        case PT_F2 ... (PT_F5 + 15):
                pos = addr - PT_F2 + ELF_FP_OFFSET(2);
                break;
        case PT_F10 ... (PT_F31 + 15):
                pos = addr - PT_F10 + ELF_FP_OFFSET(10);
                break;
        case PT_F6 ... (PT_F9 + 15):
                pos = addr - PT_F6 + ELF_FP_OFFSET(6);
                break;
        }

        if (pos != -1) {
                if (write_access)
                        ret = fpregs_set(child, NULL, pos,
                                sizeof(unsigned long), data, NULL);
                else
                        ret = fpregs_get(child, NULL, pos,
                                sizeof(unsigned long), data, NULL);
                if (ret != 0)
                        return -1;
                return 0;
        }

        switch (addr) {
        case PT_NAT_BITS:
                pos = ELF_NAT_OFFSET;
                break;
        case PT_R4 ... PT_R7:
                pos = addr - PT_R4 + ELF_GR_OFFSET(4);
                break;
        case PT_B1 ... PT_B5:
                pos = addr - PT_B1 + ELF_BR_OFFSET(1);
                break;
        case PT_AR_EC:
                pos = ELF_AR_EC_OFFSET;
                break;
        case PT_AR_LC:
                pos = ELF_AR_LC_OFFSET;
                break;
        case PT_CR_IPSR:
                pos = ELF_CR_IPSR_OFFSET;
                break;
        case PT_CR_IIP:
                pos = ELF_CR_IIP_OFFSET;
                break;
        case PT_CFM:
                pos = ELF_CFM_OFFSET;
                break;
        case PT_AR_UNAT:
                pos = ELF_AR_UNAT_OFFSET;
                break;
        case PT_AR_PFS:
                pos = ELF_AR_PFS_OFFSET;
                break;
        case PT_AR_RSC:
                pos = ELF_AR_RSC_OFFSET;
                break;
        case PT_AR_RNAT:
                pos = ELF_AR_RNAT_OFFSET;
                break;
        case PT_AR_BSPSTORE:
                pos = ELF_AR_BSPSTORE_OFFSET;
                break;
        case PT_PR:
                pos = ELF_PR_OFFSET;
                break;
        case PT_B6:
                pos = ELF_BR_OFFSET(6);
                break;
        case PT_AR_BSP:
                pos = ELF_AR_BSP_OFFSET;
                break;
        case PT_R1 ... PT_R3:
                pos = addr - PT_R1 + ELF_GR_OFFSET(1);
                break;
        case PT_R12 ... PT_R15:
                pos = addr - PT_R12 + ELF_GR_OFFSET(12);
                break;
        case PT_R8 ... PT_R11:
                pos = addr - PT_R8 + ELF_GR_OFFSET(8);
                break;
        case PT_R16 ... PT_R31:
                pos = addr - PT_R16 + ELF_GR_OFFSET(16);
                break;
        case PT_AR_CCV:
                pos = ELF_AR_CCV_OFFSET;
                break;
        case PT_AR_FPSR:
                pos = ELF_AR_FPSR_OFFSET;
                break;
        case PT_B0:
                pos = ELF_BR_OFFSET(0);
                break;
        case PT_B7:
                pos = ELF_BR_OFFSET(7);
                break;
        case PT_AR_CSD:
                pos = ELF_AR_CSD_OFFSET;
                break;
        case PT_AR_SSD:
                pos = ELF_AR_SSD_OFFSET;
                break;
        }

        if (pos != -1) {
                if (write_access)
                        ret = gpregs_set(child, NULL, pos,
                                sizeof(unsigned long), data, NULL);
                else
                        ret = gpregs_get(child, NULL, pos,
                                sizeof(unsigned long), data, NULL);
                if (ret != 0)
                        return -1;
                return 0;
        }

        /* access debug registers */
        if (addr >= PT_IBR) {
                regnum = (addr - PT_IBR) >> 3;
                ptr = &child->thread.ibr[0];
        } else {
                regnum = (addr - PT_DBR) >> 3;
                ptr = &child->thread.dbr[0];
        }

        if (regnum >= 8) {
                dprintk("ptrace: rejecting access to register "
                                "address 0x%lx\n", addr);
                return -1;
        }
#ifdef CONFIG_PERFMON
        /*
         * Check if debug registers are used by perfmon. This
         * test must be done once we know that we can do the
         * operation, i.e. the arguments are all valid, but
         * before we start modifying the state.
         *
         * Perfmon needs to keep a count of how many processes
         * are trying to modify the debug registers for system
         * wide monitoring sessions.
         *
         * We also include read access here, because they may
         * cause the PMU-installed debug register state
         * (dbr[], ibr[]) to be reset. The two arrays are also
         * used by perfmon, but we do not use
         * IA64_THREAD_DBG_VALID. The registers are restored
         * by the PMU context switch code.
         */
        if (pfm_use_debug_registers(child))
                return -1;
#endif

        if (!(child->thread.flags & IA64_THREAD_DBG_VALID)) {
                child->thread.flags |= IA64_THREAD_DBG_VALID;
                memset(child->thread.dbr, 0,
                                sizeof(child->thread.dbr));
                memset(child->thread.ibr, 0,
                                sizeof(child->thread.ibr));
        }

        ptr += regnum;

        if ((regnum & 1) && write_access) {
                /* don't let the user set kernel-level breakpoints: */
                *ptr = *data & ~(7UL << 56);
                return 0;
        }
        if (write_access)
                *ptr = *data;
        else
                *data = *ptr;
        return 0;
}

static const struct user_regset native_regsets[] = {
        {
                .core_note_type = NT_PRSTATUS,
                .n = ELF_NGREG,
                .size = sizeof(elf_greg_t), .align = sizeof(elf_greg_t),
                .get = gpregs_get, .set = gpregs_set,
                .writeback = gpregs_writeback
        },
        {
                .core_note_type = NT_PRFPREG,
                .n = ELF_NFPREG,
                .size = sizeof(elf_fpreg_t), .align = sizeof(elf_fpreg_t),
                .get = fpregs_get, .set = fpregs_set, .active = fpregs_active
        },
};

static const struct user_regset_view user_ia64_view = {
        .name = "ia64",
        .e_machine = EM_IA_64,
        .regsets = native_regsets, .n = ARRAY_SIZE(native_regsets)
};

const struct user_regset_view *task_user_regset_view(struct task_struct *tsk)
{
        return &user_ia64_view;
}

struct syscall_get_set_args {
        unsigned int i;
        unsigned int n;
        unsigned long *args;
        struct pt_regs *regs;
        int rw;
};

static void syscall_get_set_args_cb(struct unw_frame_info *info, void *data)
{
        struct syscall_get_set_args *args = data;
        struct pt_regs *pt = args->regs;
        unsigned long *krbs, cfm, ndirty;
        int i, count;

        if (unw_unwind_to_user(info) < 0)
                return;

        cfm = pt->cr_ifs;
        krbs = (unsigned long *)info->task + IA64_RBS_OFFSET/8;
        ndirty = ia64_rse_num_regs(krbs, krbs + (pt->loadrs >> 19));

        count = 0;
        if (in_syscall(pt))
                count = min_t(int, args->n, cfm & 0x7f);

        for (i = 0; i < count; i++) {
                if (args->rw)
                        *ia64_rse_skip_regs(krbs, ndirty + i + args->i) =
                                args->args[i];
                else
                        args->args[i] = *ia64_rse_skip_regs(krbs,
                                ndirty + i + args->i);
        }

        if (!args->rw) {
                while (i < args->n) {
                        args->args[i] = 0;
                        i++;
                }
        }
}

void ia64_syscall_get_set_arguments(struct task_struct *task,
        struct pt_regs *regs, unsigned int i, unsigned int n,
        unsigned long *args, int rw)
{
        struct syscall_get_set_args data = {
                .i = i,
                .n = n,
                .args = args,
                .regs = regs,
                .rw = rw,
        };

        if (task == current)
                unw_init_running(syscall_get_set_args_cb, &data);
        else {
                struct unw_frame_info ufi;
                memset(&ufi, 0, sizeof(ufi));
                unw_init_from_blocked_task(&ufi, task);
                syscall_get_set_args_cb(&ufi, &data);
        }
}