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unwind.c

/*
 * Copyright (C) 1999-2004 Hewlett-Packard Co
 *    David Mosberger-Tang <davidm@hpl.hp.com>
 * Copyright (C) 2003 Fenghua Yu <fenghua.yu@intel.com>
 *    - Change pt_regs_off() to make it less dependent on pt_regs structure.
 */
/*
 * This file implements call frame unwind support for the Linux
 * kernel.  Parsing and processing the unwind information is
 * time-consuming, so this implementation translates the unwind
 * descriptors into unwind scripts.  These scripts are very simple
 * (basically a sequence of assignments) and efficient to execute.
 * They are cached for later re-use.  Each script is specific for a
 * given instruction pointer address and the set of predicate values
 * that the script depends on (most unwind descriptors are
 * unconditional and scripts often do not depend on predicates at
 * all).  This code is based on the unwind conventions described in
 * the "IA-64 Software Conventions and Runtime Architecture" manual.
 *
 * SMP conventions:
 *    o updates to the global unwind data (in structure "unw") are serialized
 *      by the unw.lock spinlock
 *    o each unwind script has its own read-write lock; a thread must acquire
 *      a read lock before executing a script and must acquire a write lock
 *      before modifying a script
 *    o if both the unw.lock spinlock and a script's read-write lock must be
 *      acquired, then the read-write lock must be acquired first.
 */
#include <linux/module.h>
#include <linux/bootmem.h>
#include <linux/elf.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include <asm/unwind.h>

#include <asm/delay.h>
#include <asm/page.h>
#include <asm/ptrace.h>
#include <asm/ptrace_offsets.h>
#include <asm/rse.h>
#include <asm/sections.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#include "entry.h"
#include "unwind_i.h"

#define UNW_LOG_CACHE_SIZE    7     /* each unw_script is ~256 bytes in size */
#define UNW_CACHE_SIZE        (1 << UNW_LOG_CACHE_SIZE)

#define UNW_LOG_HASH_SIZE     (UNW_LOG_CACHE_SIZE + 1)
#define UNW_HASH_SIZE         (1 << UNW_LOG_HASH_SIZE)

#define UNW_STATS 0     /* WARNING: this disabled interrupts for long time-spans!! */

#ifdef UNW_DEBUG
  static unsigned int unw_debug_level = UNW_DEBUG;
#  define UNW_DEBUG_ON(n)     unw_debug_level >= n
   /* Do not code a printk level, not all debug lines end in newline */
#  define UNW_DPRINT(n, ...)  if (UNW_DEBUG_ON(n)) printk(__VA_ARGS__)
#  undef inline
#  define inline
#else /* !UNW_DEBUG */
#  define UNW_DEBUG_ON(n)  0
#  define UNW_DPRINT(n, ...)
#endif /* UNW_DEBUG */

#if UNW_STATS
# define STAT(x...)     x
#else
# define STAT(x...)
#endif

#define alloc_reg_state()     kmalloc(sizeof(struct unw_reg_state), GFP_ATOMIC)
#define free_reg_state(usr)   kfree(usr)
#define alloc_labeled_state() kmalloc(sizeof(struct unw_labeled_state), GFP_ATOMIC)
#define free_labeled_state(usr)     kfree(usr)

typedef unsigned long unw_word;
typedef unsigned char unw_hash_index_t;

static struct {
      spinlock_t lock;              /* spinlock for unwind data */

      /* list of unwind tables (one per load-module) */
      struct unw_table *tables;

      unsigned long r0;             /* constant 0 for r0 */

      /* table of registers that prologues can save (and order in which they're saved): */
      const unsigned char save_order[8];

      /* maps a preserved register index (preg_index) to corresponding switch_stack offset: */
      unsigned short sw_off[sizeof(struct unw_frame_info) / 8];

      unsigned short lru_head;            /* index of lead-recently used script */
      unsigned short lru_tail;            /* index of most-recently used script */

      /* index into unw_frame_info for preserved register i */
      unsigned short preg_index[UNW_NUM_REGS];

      short pt_regs_offsets[32];

      /* unwind table for the kernel: */
      struct unw_table kernel_table;

      /* unwind table describing the gate page (kernel code that is mapped into user space): */
      size_t gate_table_size;
      unsigned long *gate_table;

      /* hash table that maps instruction pointer to script index: */
      unsigned short hash[UNW_HASH_SIZE];

      /* script cache: */
      struct unw_script cache[UNW_CACHE_SIZE];

# ifdef UNW_DEBUG
      const char *preg_name[UNW_NUM_REGS];
# endif
# if UNW_STATS
      struct {
            struct {
                  int lookups;
                  int hinted_hits;
                  int normal_hits;
                  int collision_chain_traversals;
            } cache;
            struct {
                  unsigned long build_time;
                  unsigned long run_time;
                  unsigned long parse_time;
                  int builds;
                  int news;
                  int collisions;
                  int runs;
            } script;
            struct {
                  unsigned long init_time;
                  unsigned long unwind_time;
                  int inits;
                  int unwinds;
            } api;
      } stat;
# endif
} unw = {
      .tables = &unw.kernel_table,
      .lock = __SPIN_LOCK_UNLOCKED(unw.lock),
      .save_order = {
            UNW_REG_RP, UNW_REG_PFS, UNW_REG_PSP, UNW_REG_PR,
            UNW_REG_UNAT, UNW_REG_LC, UNW_REG_FPSR, UNW_REG_PRI_UNAT_GR
      },
      .preg_index = {
            offsetof(struct unw_frame_info, pri_unat_loc)/8,      /* PRI_UNAT_GR */
            offsetof(struct unw_frame_info, pri_unat_loc)/8,      /* PRI_UNAT_MEM */
            offsetof(struct unw_frame_info, bsp_loc)/8,
            offsetof(struct unw_frame_info, bspstore_loc)/8,
            offsetof(struct unw_frame_info, pfs_loc)/8,
            offsetof(struct unw_frame_info, rnat_loc)/8,
            offsetof(struct unw_frame_info, psp)/8,
            offsetof(struct unw_frame_info, rp_loc)/8,
            offsetof(struct unw_frame_info, r4)/8,
            offsetof(struct unw_frame_info, r5)/8,
            offsetof(struct unw_frame_info, r6)/8,
            offsetof(struct unw_frame_info, r7)/8,
            offsetof(struct unw_frame_info, unat_loc)/8,
            offsetof(struct unw_frame_info, pr_loc)/8,
            offsetof(struct unw_frame_info, lc_loc)/8,
            offsetof(struct unw_frame_info, fpsr_loc)/8,
            offsetof(struct unw_frame_info, b1_loc)/8,
            offsetof(struct unw_frame_info, b2_loc)/8,
            offsetof(struct unw_frame_info, b3_loc)/8,
            offsetof(struct unw_frame_info, b4_loc)/8,
            offsetof(struct unw_frame_info, b5_loc)/8,
            offsetof(struct unw_frame_info, f2_loc)/8,
            offsetof(struct unw_frame_info, f3_loc)/8,
            offsetof(struct unw_frame_info, f4_loc)/8,
            offsetof(struct unw_frame_info, f5_loc)/8,
            offsetof(struct unw_frame_info, fr_loc[16 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[17 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[18 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[19 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[20 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[21 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[22 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[23 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[24 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[25 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[26 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[27 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[28 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[29 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[30 - 16])/8,
            offsetof(struct unw_frame_info, fr_loc[31 - 16])/8,
      },
      .pt_regs_offsets = {
            [0] = -1,
            offsetof(struct pt_regs,  r1),
            offsetof(struct pt_regs,  r2),
            offsetof(struct pt_regs,  r3),
            [4] = -1, [5] = -1, [6] = -1, [7] = -1,
            offsetof(struct pt_regs,  r8),
            offsetof(struct pt_regs,  r9),
            offsetof(struct pt_regs, r10),
            offsetof(struct pt_regs, r11),
            offsetof(struct pt_regs, r12),
            offsetof(struct pt_regs, r13),
            offsetof(struct pt_regs, r14),
            offsetof(struct pt_regs, r15),
            offsetof(struct pt_regs, r16),
            offsetof(struct pt_regs, r17),
            offsetof(struct pt_regs, r18),
            offsetof(struct pt_regs, r19),
            offsetof(struct pt_regs, r20),
            offsetof(struct pt_regs, r21),
            offsetof(struct pt_regs, r22),
            offsetof(struct pt_regs, r23),
            offsetof(struct pt_regs, r24),
            offsetof(struct pt_regs, r25),
            offsetof(struct pt_regs, r26),
            offsetof(struct pt_regs, r27),
            offsetof(struct pt_regs, r28),
            offsetof(struct pt_regs, r29),
            offsetof(struct pt_regs, r30),
            offsetof(struct pt_regs, r31),
      },
      .hash = { [0 ... UNW_HASH_SIZE - 1] = -1 },
#ifdef UNW_DEBUG
      .preg_name = {
            "pri_unat_gr", "pri_unat_mem", "bsp", "bspstore", "ar.pfs", "ar.rnat", "psp", "rp",
            "r4", "r5", "r6", "r7",
            "ar.unat", "pr", "ar.lc", "ar.fpsr",
            "b1", "b2", "b3", "b4", "b5",
            "f2", "f3", "f4", "f5",
            "f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23",
            "f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31"
      }
#endif
};

static inline int
read_only (void *addr)
{
      return (unsigned long) ((char *) addr - (char *) &unw.r0) < sizeof(unw.r0);
}

/*
 * Returns offset of rREG in struct pt_regs.
 */
static inline unsigned long
pt_regs_off (unsigned long reg)
{
      short off = -1;

      if (reg < ARRAY_SIZE(unw.pt_regs_offsets))
            off = unw.pt_regs_offsets[reg];

      if (off < 0) {
            UNW_DPRINT(0, "unwind.%s: bad scratch reg r%lu\n", __FUNCTION__, reg);
            off = 0;
      }
      return (unsigned long) off;
}

static inline struct pt_regs *
get_scratch_regs (struct unw_frame_info *info)
{
      if (!info->pt) {
            /* This should not happen with valid unwind info.  */
            UNW_DPRINT(0, "unwind.%s: bad unwind info: resetting info->pt\n", __FUNCTION__);
            if (info->flags & UNW_FLAG_INTERRUPT_FRAME)
                  info->pt = (unsigned long) ((struct pt_regs *) info->psp - 1);
            else
                  info->pt = info->sp - 16;
      }
      UNW_DPRINT(3, "unwind.%s: sp 0x%lx pt 0x%lx\n", __FUNCTION__, info->sp, info->pt);
      return (struct pt_regs *) info->pt;
}

/* Unwind accessors.  */

int
unw_access_gr (struct unw_frame_info *info, int regnum, unsigned long *val, char *nat, int write)
{
      unsigned long *addr, *nat_addr, nat_mask = 0, dummy_nat;
      struct unw_ireg *ireg;
      struct pt_regs *pt;

      if ((unsigned) regnum - 1 >= 127) {
            if (regnum == 0 && !write) {
                  *val = 0;   /* read r0 always returns 0 */
                  *nat = 0;
                  return 0;
            }
            UNW_DPRINT(0, "unwind.%s: trying to access non-existent r%u\n",
                     __FUNCTION__, regnum);
            return -1;
      }

      if (regnum < 32) {
            if (regnum >= 4 && regnum <= 7) {
                  /* access a preserved register */
                  ireg = &info->r4 + (regnum - 4);
                  addr = ireg->loc;
                  if (addr) {
                        nat_addr = addr + ireg->nat.off;
                        switch (ireg->nat.type) {
                              case UNW_NAT_VAL:
                              /* simulate getf.sig/setf.sig */
                              if (write) {
                                    if (*nat) {
                                          /* write NaTVal and be done with it */
                                          addr[0] = 0;
                                          addr[1] = 0x1fffe;
                                          return 0;
                                    }
                                    addr[1] = 0x1003e;
                              } else {
                                    if (addr[0] == 0 && addr[1] == 0x1ffe) {
                                          /* return NaT and be done with it */
                                          *val = 0;
                                          *nat = 1;
                                          return 0;
                                    }
                              }
                              /* fall through */
                              case UNW_NAT_NONE:
                              dummy_nat = 0;
                              nat_addr = &dummy_nat;
                              break;

                              case UNW_NAT_MEMSTK:
                              nat_mask = (1UL << ((long) addr & 0x1f8)/8);
                              break;

                              case UNW_NAT_REGSTK:
                              nat_addr = ia64_rse_rnat_addr(addr);
                              if ((unsigned long) addr < info->regstk.limit
                                  || (unsigned long) addr >= info->regstk.top)
                              {
                                    UNW_DPRINT(0, "unwind.%s: %p outside of regstk "
                                          "[0x%lx-0x%lx)\n",
                                          __FUNCTION__, (void *) addr,
                                          info->regstk.limit,
                                          info->regstk.top);
                                    return -1;
                              }
                              if ((unsigned long) nat_addr >= info->regstk.top)
                                    nat_addr = &info->sw->ar_rnat;
                              nat_mask = (1UL << ia64_rse_slot_num(addr));
                              break;
                        }
                  } else {
                        addr = &info->sw->r4 + (regnum - 4);
                        nat_addr = &info->sw->ar_unat;
                        nat_mask = (1UL << ((long) addr & 0x1f8)/8);
                  }
            } else {
                  /* access a scratch register */
                  pt = get_scratch_regs(info);
                  addr = (unsigned long *) ((unsigned long)pt + pt_regs_off(regnum));
                  if (info->pri_unat_loc)
                        nat_addr = info->pri_unat_loc;
                  else
                        nat_addr = &info->sw->caller_unat;
                  nat_mask = (1UL << ((long) addr & 0x1f8)/8);
            }
      } else {
            /* access a stacked register */
            addr = ia64_rse_skip_regs((unsigned long *) info->bsp, regnum - 32);
            nat_addr = ia64_rse_rnat_addr(addr);
            if ((unsigned long) addr < info->regstk.limit
                || (unsigned long) addr >= info->regstk.top)
            {
                  UNW_DPRINT(0, "unwind.%s: ignoring attempt to access register outside "
                           "of rbs\n",  __FUNCTION__);
                  return -1;
            }
            if ((unsigned long) nat_addr >= info->regstk.top)
                  nat_addr = &info->sw->ar_rnat;
            nat_mask = (1UL << ia64_rse_slot_num(addr));
      }

      if (write) {
            if (read_only(addr)) {
                  UNW_DPRINT(0, "unwind.%s: ignoring attempt to write read-only location\n",
                        __FUNCTION__);
            } else {
                  *addr = *val;
                  if (*nat)
                        *nat_addr |= nat_mask;
                  else
                        *nat_addr &= ~nat_mask;
            }
      } else {
            if ((*nat_addr & nat_mask) == 0) {
                  *val = *addr;
                  *nat = 0;
            } else {
                  *val = 0;   /* if register is a NaT, *addr may contain kernel data! */
                  *nat = 1;
            }
      }
      return 0;
}
EXPORT_SYMBOL(unw_access_gr);

int
unw_access_br (struct unw_frame_info *info, int regnum, unsigned long *val, int write)
{
      unsigned long *addr;
      struct pt_regs *pt;

      switch (regnum) {
            /* scratch: */
            case 0: pt = get_scratch_regs(info); addr = &pt->b0; break;
            case 6: pt = get_scratch_regs(info); addr = &pt->b6; break;
            case 7: pt = get_scratch_regs(info); addr = &pt->b7; break;

            /* preserved: */
            case 1: case 2: case 3: case 4: case 5:
            addr = *(&info->b1_loc + (regnum - 1));
            if (!addr)
                  addr = &info->sw->b1 + (regnum - 1);
            break;

            default:
            UNW_DPRINT(0, "unwind.%s: trying to access non-existent b%u\n",
                     __FUNCTION__, regnum);
            return -1;
      }
      if (write)
            if (read_only(addr)) {
                  UNW_DPRINT(0, "unwind.%s: ignoring attempt to write read-only location\n",
                        __FUNCTION__);
            } else
                  *addr = *val;
      else
            *val = *addr;
      return 0;
}
EXPORT_SYMBOL(unw_access_br);

int
unw_access_fr (struct unw_frame_info *info, int regnum, struct ia64_fpreg *val, int write)
{
      struct ia64_fpreg *addr = NULL;
      struct pt_regs *pt;

      if ((unsigned) (regnum - 2) >= 126) {
            UNW_DPRINT(0, "unwind.%s: trying to access non-existent f%u\n",
                     __FUNCTION__, regnum);
            return -1;
      }

      if (regnum <= 5) {
            addr = *(&info->f2_loc + (regnum - 2));
            if (!addr)
                  addr = &info->sw->f2 + (regnum - 2);
      } else if (regnum <= 15) {
            if (regnum <= 11) {
                  pt = get_scratch_regs(info);
                  addr = &pt->f6  + (regnum - 6);
            }
            else
                  addr = &info->sw->f12 + (regnum - 12);
      } else if (regnum <= 31) {
            addr = info->fr_loc[regnum - 16];
            if (!addr)
                  addr = &info->sw->f16 + (regnum - 16);
      } else {
            struct task_struct *t = info->task;

            if (write)
                  ia64_sync_fph(t);
            else
                  ia64_flush_fph(t);
            addr = t->thread.fph + (regnum - 32);
      }

      if (write)
            if (read_only(addr)) {
                  UNW_DPRINT(0, "unwind.%s: ignoring attempt to write read-only location\n",
                        __FUNCTION__);
            } else
                  *addr = *val;
      else
            *val = *addr;
      return 0;
}
EXPORT_SYMBOL(unw_access_fr);

int
unw_access_ar (struct unw_frame_info *info, int regnum, unsigned long *val, int write)
{
      unsigned long *addr;
      struct pt_regs *pt;

      switch (regnum) {
            case UNW_AR_BSP:
            addr = info->bsp_loc;
            if (!addr)
                  addr = &info->sw->ar_bspstore;
            break;

            case UNW_AR_BSPSTORE:
            addr = info->bspstore_loc;
            if (!addr)
                  addr = &info->sw->ar_bspstore;
            break;

            case UNW_AR_PFS:
            addr = info->pfs_loc;
            if (!addr)
                  addr = &info->sw->ar_pfs;
            break;

            case UNW_AR_RNAT:
            addr = info->rnat_loc;
            if (!addr)
                  addr = &info->sw->ar_rnat;
            break;

            case UNW_AR_UNAT:
            addr = info->unat_loc;
            if (!addr)
                  addr = &info->sw->caller_unat;
            break;

            case UNW_AR_LC:
            addr = info->lc_loc;
            if (!addr)
                  addr = &info->sw->ar_lc;
            break;

            case UNW_AR_EC:
            if (!info->cfm_loc)
                  return -1;
            if (write)
                  *info->cfm_loc =
                        (*info->cfm_loc & ~(0x3fUL << 52)) | ((*val & 0x3f) << 52);
            else
                  *val = (*info->cfm_loc >> 52) & 0x3f;
            return 0;

            case UNW_AR_FPSR:
            addr = info->fpsr_loc;
            if (!addr)
                  addr = &info->sw->ar_fpsr;
            break;

            case UNW_AR_RSC:
            pt = get_scratch_regs(info);
            addr = &pt->ar_rsc;
            break;

            case UNW_AR_CCV:
            pt = get_scratch_regs(info);
            addr = &pt->ar_ccv;
            break;

            case UNW_AR_CSD:
            pt = get_scratch_regs(info);
            addr = &pt->ar_csd;
            break;

            case UNW_AR_SSD:
            pt = get_scratch_regs(info);
            addr = &pt->ar_ssd;
            break;

            default:
            UNW_DPRINT(0, "unwind.%s: trying to access non-existent ar%u\n",
                     __FUNCTION__, regnum);
            return -1;
      }

      if (write) {
            if (read_only(addr)) {
                  UNW_DPRINT(0, "unwind.%s: ignoring attempt to write read-only location\n",
                        __FUNCTION__);
            } else
                  *addr = *val;
      } else
            *val = *addr;
      return 0;
}
EXPORT_SYMBOL(unw_access_ar);

int
unw_access_pr (struct unw_frame_info *info, unsigned long *val, int write)
{
      unsigned long *addr;

      addr = info->pr_loc;
      if (!addr)
            addr = &info->sw->pr;

      if (write) {
            if (read_only(addr)) {
                  UNW_DPRINT(0, "unwind.%s: ignoring attempt to write read-only location\n",
                        __FUNCTION__);
            } else
                  *addr = *val;
      } else
            *val = *addr;
      return 0;
}
EXPORT_SYMBOL(unw_access_pr);


/* Routines to manipulate the state stack.  */

static inline void
push (struct unw_state_record *sr)
{
      struct unw_reg_state *rs;

      rs = alloc_reg_state();
      if (!rs) {
            printk(KERN_ERR "unwind: cannot stack reg state!\n");
            return;
      }
      memcpy(rs, &sr->curr, sizeof(*rs));
      sr->curr.next = rs;
}

static void
pop (struct unw_state_record *sr)
{
      struct unw_reg_state *rs = sr->curr.next;

      if (!rs) {
            printk(KERN_ERR "unwind: stack underflow!\n");
            return;
      }
      memcpy(&sr->curr, rs, sizeof(*rs));
      free_reg_state(rs);
}

/* Make a copy of the state stack.  Non-recursive to avoid stack overflows.  */
static struct unw_reg_state *
dup_state_stack (struct unw_reg_state *rs)
{
      struct unw_reg_state *copy, *prev = NULL, *first = NULL;

      while (rs) {
            copy = alloc_reg_state();
            if (!copy) {
                  printk(KERN_ERR "unwind.dup_state_stack: out of memory\n");
                  return NULL;
            }
            memcpy(copy, rs, sizeof(*copy));
            if (first)
                  prev->next = copy;
            else
                  first = copy;
            rs = rs->next;
            prev = copy;
      }
      return first;
}

/* Free all stacked register states (but not RS itself).  */
static void
free_state_stack (struct unw_reg_state *rs)
{
      struct unw_reg_state *p, *next;

      for (p = rs->next; p != NULL; p = next) {
            next = p->next;
            free_reg_state(p);
      }
      rs->next = NULL;
}

/* Unwind decoder routines */

static enum unw_register_index __attribute_const__
decode_abreg (unsigned char abreg, int memory)
{
      switch (abreg) {
            case 0x04 ... 0x07: return UNW_REG_R4 + (abreg - 0x04);
            case 0x22 ... 0x25: return UNW_REG_F2 + (abreg - 0x22);
            case 0x30 ... 0x3f: return UNW_REG_F16 + (abreg - 0x30);
            case 0x41 ... 0x45: return UNW_REG_B1 + (abreg - 0x41);
            case 0x60: return UNW_REG_PR;
            case 0x61: return UNW_REG_PSP;
            case 0x62: return memory ? UNW_REG_PRI_UNAT_MEM : UNW_REG_PRI_UNAT_GR;
            case 0x63: return UNW_REG_RP;
            case 0x64: return UNW_REG_BSP;
            case 0x65: return UNW_REG_BSPSTORE;
            case 0x66: return UNW_REG_RNAT;
            case 0x67: return UNW_REG_UNAT;
            case 0x68: return UNW_REG_FPSR;
            case 0x69: return UNW_REG_PFS;
            case 0x6a: return UNW_REG_LC;
            default:
            break;
      }
      UNW_DPRINT(0, "unwind.%s: bad abreg=0x%x\n", __FUNCTION__, abreg);
      return UNW_REG_LC;
}

static void
set_reg (struct unw_reg_info *reg, enum unw_where where, int when, unsigned long val)
{
      reg->val = val;
      reg->where = where;
      if (reg->when == UNW_WHEN_NEVER)
            reg->when = when;
}

static void
alloc_spill_area (unsigned long *offp, unsigned long regsize,
              struct unw_reg_info *lo, struct unw_reg_info *hi)
{
      struct unw_reg_info *reg;

      for (reg = hi; reg >= lo; --reg) {
            if (reg->where == UNW_WHERE_SPILL_HOME) {
                  reg->where = UNW_WHERE_PSPREL;
                  *offp -= regsize;
                  reg->val = *offp;
            }
      }
}

static inline void
spill_next_when (struct unw_reg_info **regp, struct unw_reg_info *lim, unw_word t)
{
      struct unw_reg_info *reg;

      for (reg = *regp; reg <= lim; ++reg) {
            if (reg->where == UNW_WHERE_SPILL_HOME) {
                  reg->when = t;
                  *regp = reg + 1;
                  return;
            }
      }
      UNW_DPRINT(0, "unwind.%s: excess spill!\n",  __FUNCTION__);
}

static inline void
finish_prologue (struct unw_state_record *sr)
{
      struct unw_reg_info *reg;
      unsigned long off;
      int i;

      /*
       * First, resolve implicit register save locations (see Section "11.4.2.3 Rules
       * for Using Unwind Descriptors", rule 3):
       */
      for (i = 0; i < (int) ARRAY_SIZE(unw.save_order); ++i) {
            reg = sr->curr.reg + unw.save_order[i];
            if (reg->where == UNW_WHERE_GR_SAVE) {
                  reg->where = UNW_WHERE_GR;
                  reg->val = sr->gr_save_loc++;
            }
      }

      /*
       * Next, compute when the fp, general, and branch registers get
       * saved.  This must come before alloc_spill_area() because
       * we need to know which registers are spilled to their home
       * locations.
       */
      if (sr->imask) {
            unsigned char kind, mask = 0, *cp = sr->imask;
            int t;
            static const unsigned char limit[3] = {
                  UNW_REG_F31, UNW_REG_R7, UNW_REG_B5
            };
            struct unw_reg_info *(regs[3]);

            regs[0] = sr->curr.reg + UNW_REG_F2;
            regs[1] = sr->curr.reg + UNW_REG_R4;
            regs[2] = sr->curr.reg + UNW_REG_B1;

            for (t = 0; t < sr->region_len; ++t) {
                  if ((t & 3) == 0)
                        mask = *cp++;
                  kind = (mask >> 2*(3-(t & 3))) & 3;
                  if (kind > 0)
                        spill_next_when(&regs[kind - 1], sr->curr.reg + limit[kind - 1],
                                    sr->region_start + t);
            }
      }
      /*
       * Next, lay out the memory stack spill area:
       */
      if (sr->any_spills) {
            off = sr->spill_offset;
            alloc_spill_area(&off, 16, sr->curr.reg + UNW_REG_F2, sr->curr.reg + UNW_REG_F31);
            alloc_spill_area(&off,  8, sr->curr.reg + UNW_REG_B1, sr->curr.reg + UNW_REG_B5);
            alloc_spill_area(&off,  8, sr->curr.reg + UNW_REG_R4, sr->curr.reg + UNW_REG_R7);
      }
}

/*
 * Region header descriptors.
 */

static void
desc_prologue (int body, unw_word rlen, unsigned char mask, unsigned char grsave,
             struct unw_state_record *sr)
{
      int i, region_start;

      if (!(sr->in_body || sr->first_region))
            finish_prologue(sr);
      sr->first_region = 0;

      /* check if we're done: */
      if (sr->when_target < sr->region_start + sr->region_len) {
            sr->done = 1;
            return;
      }

      region_start = sr->region_start + sr->region_len;

      for (i = 0; i < sr->epilogue_count; ++i)
            pop(sr);
      sr->epilogue_count = 0;
      sr->epilogue_start = UNW_WHEN_NEVER;

      sr->region_start = region_start;
      sr->region_len = rlen;
      sr->in_body = body;

      if (!body) {
            push(sr);

            for (i = 0; i < 4; ++i) {
                  if (mask & 0x8)
                        set_reg(sr->curr.reg + unw.save_order[i], UNW_WHERE_GR,
                              sr->region_start + sr->region_len - 1, grsave++);
                  mask <<= 1;
            }
            sr->gr_save_loc = grsave;
            sr->any_spills = 0;
            sr->imask = NULL;
            sr->spill_offset = 0x10;      /* default to psp+16 */
      }
}

/*
 * Prologue descriptors.
 */

static inline void
desc_abi (unsigned char abi, unsigned char context, struct unw_state_record *sr)
{
      if (abi == 3 && context == 'i') {
            sr->flags |= UNW_FLAG_INTERRUPT_FRAME;
            UNW_DPRINT(3, "unwind.%s: interrupt frame\n",  __FUNCTION__);
      }
      else
            UNW_DPRINT(0, "unwind%s: ignoring unwabi(abi=0x%x,context=0x%x)\n",
                        __FUNCTION__, abi, context);
}

static inline void
desc_br_gr (unsigned char brmask, unsigned char gr, struct unw_state_record *sr)
{
      int i;

      for (i = 0; i < 5; ++i) {
            if (brmask & 1)
                  set_reg(sr->curr.reg + UNW_REG_B1 + i, UNW_WHERE_GR,
                        sr->region_start + sr->region_len - 1, gr++);
            brmask >>= 1;
      }
}

static inline void
desc_br_mem (unsigned char brmask, struct unw_state_record *sr)
{
      int i;

      for (i = 0; i < 5; ++i) {
            if (brmask & 1) {
                  set_reg(sr->curr.reg + UNW_REG_B1 + i, UNW_WHERE_SPILL_HOME,
                        sr->region_start + sr->region_len - 1, 0);
                  sr->any_spills = 1;
            }
            brmask >>= 1;
      }
}

static inline void
desc_frgr_mem (unsigned char grmask, unw_word frmask, struct unw_state_record *sr)
{
      int i;

      for (i = 0; i < 4; ++i) {
            if ((grmask & 1) != 0) {
                  set_reg(sr->curr.reg + UNW_REG_R4 + i, UNW_WHERE_SPILL_HOME,
                        sr->region_start + sr->region_len - 1, 0);
                  sr->any_spills = 1;
            }
            grmask >>= 1;
      }
      for (i = 0; i < 20; ++i) {
            if ((frmask & 1) != 0) {
                  int base = (i < 4) ? UNW_REG_F2 : UNW_REG_F16 - 4;
                  set_reg(sr->curr.reg + base + i, UNW_WHERE_SPILL_HOME,
                        sr->region_start + sr->region_len - 1, 0);
                  sr->any_spills = 1;
            }
            frmask >>= 1;
      }
}

static inline void
desc_fr_mem (unsigned char frmask, struct unw_state_record *sr)
{
      int i;

      for (i = 0; i < 4; ++i) {
            if ((frmask & 1) != 0) {
                  set_reg(sr->curr.reg + UNW_REG_F2 + i, UNW_WHERE_SPILL_HOME,
                        sr->region_start + sr->region_len - 1, 0);
                  sr->any_spills = 1;
            }
            frmask >>= 1;
      }
}

static inline void
desc_gr_gr (unsigned char grmask, unsigned char gr, struct unw_state_record *sr)
{
      int i;

      for (i = 0; i < 4; ++i) {
            if ((grmask & 1) != 0)
                  set_reg(sr->curr.reg + UNW_REG_R4 + i, UNW_WHERE_GR,
                        sr->region_start + sr->region_len - 1, gr++);
            grmask >>= 1;
      }
}

static inline void
desc_gr_mem (unsigned char grmask, struct unw_state_record *sr)
{
      int i;

      for (i = 0; i < 4; ++i) {
            if ((grmask & 1) != 0) {
                  set_reg(sr->curr.reg + UNW_REG_R4 + i, UNW_WHERE_SPILL_HOME,
                        sr->region_start + sr->region_len - 1, 0);
                  sr->any_spills = 1;
            }
            grmask >>= 1;
      }
}

static inline void
desc_mem_stack_f (unw_word t, unw_word size, struct unw_state_record *sr)
{
      set_reg(sr->curr.reg + UNW_REG_PSP, UNW_WHERE_NONE,
            sr->region_start + min_t(int, t, sr->region_len - 1), 16*size);
}

static inline void
desc_mem_stack_v (unw_word t, struct unw_state_record *sr)
{
      sr->curr.reg[UNW_REG_PSP].when = sr->region_start + min_t(int, t, sr->region_len - 1);
}

static inline void
desc_reg_gr (unsigned char reg, unsigned char dst, struct unw_state_record *sr)
{
      set_reg(sr->curr.reg + reg, UNW_WHERE_GR, sr->region_start + sr->region_len - 1, dst);
}

static inline void
desc_reg_psprel (unsigned char reg, unw_word pspoff, struct unw_state_record *sr)
{
      set_reg(sr->curr.reg + reg, UNW_WHERE_PSPREL, sr->region_start + sr->region_len - 1,
            0x10 - 4*pspoff);
}

static inline void
desc_reg_sprel (unsigned char reg, unw_word spoff, struct unw_state_record *sr)
{
      set_reg(sr->curr.reg + reg, UNW_WHERE_SPREL, sr->region_start + sr->region_len - 1,
            4*spoff);
}

static inline void
desc_rp_br (unsigned char dst, struct unw_state_record *sr)
{
      sr->return_link_reg = dst;
}

static inline void
desc_reg_when (unsigned char regnum, unw_word t, struct unw_state_record *sr)
{
      struct unw_reg_info *reg = sr->curr.reg + regnum;

      if (reg->where == UNW_WHERE_NONE)
            reg->where = UNW_WHERE_GR_SAVE;
      reg->when = sr->region_start + min_t(int, t, sr->region_len - 1);
}

static inline void
desc_spill_base (unw_word pspoff, struct unw_state_record *sr)
{
      sr->spill_offset = 0x10 - 4*pspoff;
}

static inline unsigned char *
desc_spill_mask (unsigned char *imaskp, struct unw_state_record *sr)
{
      sr->imask = imaskp;
      return imaskp + (2*sr->region_len + 7)/8;
}

/*
 * Body descriptors.
 */
static inline void
desc_epilogue (unw_word t, unw_word ecount, struct unw_state_record *sr)
{
      sr->epilogue_start = sr->region_start + sr->region_len - 1 - t;
      sr->epilogue_count = ecount + 1;
}

static inline void
desc_copy_state (unw_word label, struct unw_state_record *sr)
{
      struct unw_labeled_state *ls;

      for (ls = sr->labeled_states; ls; ls = ls->next) {
            if (ls->label == label) {
                  free_state_stack(&sr->curr);
                  memcpy(&sr->curr, &ls->saved_state, sizeof(sr->curr));
                  sr->curr.next = dup_state_stack(ls->saved_state.next);
                  return;
            }
      }
      printk(KERN_ERR "unwind: failed to find state labeled 0x%lx\n", label);
}

static inline void
desc_label_state (unw_word label, struct unw_state_record *sr)
{
      struct unw_labeled_state *ls;

      ls = alloc_labeled_state();
      if (!ls) {
            printk(KERN_ERR "unwind.desc_label_state(): out of memory\n");
            return;
      }
      ls->label = label;
      memcpy(&ls->saved_state, &sr->curr, sizeof(ls->saved_state));
      ls->saved_state.next = dup_state_stack(sr->curr.next);

      /* insert into list of labeled states: */
      ls->next = sr->labeled_states;
      sr->labeled_states = ls;
}

/*
 * General descriptors.
 */

static inline int
desc_is_active (unsigned char qp, unw_word t, struct unw_state_record *sr)
{
      if (sr->when_target <= sr->region_start + min_t(int, t, sr->region_len - 1))
            return 0;
      if (qp > 0) {
            if ((sr->pr_val & (1UL << qp)) == 0)
                  return 0;
            sr->pr_mask |= (1UL << qp);
      }
      return 1;
}

static inline void
desc_restore_p (unsigned char qp, unw_word t, unsigned char abreg, struct unw_state_record *sr)
{
      struct unw_reg_info *r;

      if (!desc_is_active(qp, t, sr))
            return;

      r = sr->curr.reg + decode_abreg(abreg, 0);
      r->where = UNW_WHERE_NONE;
      r->when = UNW_WHEN_NEVER;
      r->val = 0;
}

static inline void
desc_spill_reg_p (unsigned char qp, unw_word t, unsigned char abreg, unsigned char x,
                 unsigned char ytreg, struct unw_state_record *sr)
{
      enum unw_where where = UNW_WHERE_GR;
      struct unw_reg_info *r;

      if (!desc_is_active(qp, t, sr))
            return;

      if (x)
            where = UNW_WHERE_BR;
      else if (ytreg & 0x80)
            where = UNW_WHERE_FR;

      r = sr->curr.reg + decode_abreg(abreg, 0);
      r->where = where;
      r->when = sr->region_start + min_t(int, t, sr->region_len - 1);
      r->val = (ytreg & 0x7f);
}

static inline void
desc_spill_psprel_p (unsigned char qp, unw_word t, unsigned char abreg, unw_word pspoff,
                 struct unw_state_record *sr)
{
      struct unw_reg_info *r;

      if (!desc_is_active(qp, t, sr))
            return;

      r = sr->curr.reg + decode_abreg(abreg, 1);
      r->where = UNW_WHERE_PSPREL;
      r->when = sr->region_start + min_t(int, t, sr->region_len - 1);
      r->val = 0x10 - 4*pspoff;
}

static inline void
desc_spill_sprel_p (unsigned char qp, unw_word t, unsigned char abreg, unw_word spoff,
                   struct unw_state_record *sr)
{
      struct unw_reg_info *r;

      if (!desc_is_active(qp, t, sr))
            return;

      r = sr->curr.reg + decode_abreg(abreg, 1);
      r->where = UNW_WHERE_SPREL;
      r->when = sr->region_start + min_t(int, t, sr->region_len - 1);
      r->val = 4*spoff;
}

#define UNW_DEC_BAD_CODE(code)                  printk(KERN_ERR "unwind: unknown code 0x%02x\n", \
                                           code);

/*
 * region headers:
 */
#define UNW_DEC_PROLOGUE_GR(fmt,r,m,gr,arg)     desc_prologue(0,r,m,gr,arg)
#define UNW_DEC_PROLOGUE(fmt,b,r,arg)           desc_prologue(b,r,0,32,arg)
/*
 * prologue descriptors:
 */
#define UNW_DEC_ABI(fmt,a,c,arg)          desc_abi(a,c,arg)
#define UNW_DEC_BR_GR(fmt,b,g,arg)        desc_br_gr(b,g,arg)
#define UNW_DEC_BR_MEM(fmt,b,arg)         desc_br_mem(b,arg)
#define UNW_DEC_FRGR_MEM(fmt,g,f,arg)           desc_frgr_mem(g,f,arg)
#define UNW_DEC_FR_MEM(fmt,f,arg)         desc_fr_mem(f,arg)
#define UNW_DEC_GR_GR(fmt,m,g,arg)        desc_gr_gr(m,g,arg)
#define UNW_DEC_GR_MEM(fmt,m,arg)         desc_gr_mem(m,arg)
#define UNW_DEC_MEM_STACK_F(fmt,t,s,arg)  desc_mem_stack_f(t,s,arg)
#define UNW_DEC_MEM_STACK_V(fmt,t,arg)          desc_mem_stack_v(t,arg)
#define UNW_DEC_REG_GR(fmt,r,d,arg)       desc_reg_gr(r,d,arg)
#define UNW_DEC_REG_PSPREL(fmt,r,o,arg)         desc_reg_psprel(r,o,arg)
#define UNW_DEC_REG_SPREL(fmt,r,o,arg)          desc_reg_sprel(r,o,arg)
#define UNW_DEC_REG_WHEN(fmt,r,t,arg)           desc_reg_when(r,t,arg)
#define UNW_DEC_PRIUNAT_WHEN_GR(fmt,t,arg)      desc_reg_when(UNW_REG_PRI_UNAT_GR,t,arg)
#define UNW_DEC_PRIUNAT_WHEN_MEM(fmt,t,arg)     desc_reg_when(UNW_REG_PRI_UNAT_MEM,t,arg)
#define UNW_DEC_PRIUNAT_GR(fmt,r,arg)           desc_reg_gr(UNW_REG_PRI_UNAT_GR,r,arg)
#define UNW_DEC_PRIUNAT_PSPREL(fmt,o,arg) desc_reg_psprel(UNW_REG_PRI_UNAT_MEM,o,arg)
#define UNW_DEC_PRIUNAT_SPREL(fmt,o,arg)  desc_reg_sprel(UNW_REG_PRI_UNAT_MEM,o,arg)
#define UNW_DEC_RP_BR(fmt,d,arg)          desc_rp_br(d,arg)
#define UNW_DEC_SPILL_BASE(fmt,o,arg)           desc_spill_base(o,arg)
#define UNW_DEC_SPILL_MASK(fmt,m,arg)           (m = desc_spill_mask(m,arg))
/*
 * body descriptors:
 */
#define UNW_DEC_EPILOGUE(fmt,t,c,arg)           desc_epilogue(t,c,arg)
#define UNW_DEC_COPY_STATE(fmt,l,arg)           desc_copy_state(l,arg)
#define UNW_DEC_LABEL_STATE(fmt,l,arg)          desc_label_state(l,arg)
/*
 * general unwind descriptors:
 */
#define UNW_DEC_SPILL_REG_P(f,p,t,a,x,y,arg)    desc_spill_reg_p(p,t,a,x,y,arg)
#define UNW_DEC_SPILL_REG(f,t,a,x,y,arg)  desc_spill_reg_p(0,t,a,x,y,arg)
#define UNW_DEC_SPILL_PSPREL_P(f,p,t,a,o,arg)   desc_spill_psprel_p(p,t,a,o,arg)
#define UNW_DEC_SPILL_PSPREL(f,t,a,o,arg) desc_spill_psprel_p(0,t,a,o,arg)
#define UNW_DEC_SPILL_SPREL_P(f,p,t,a,o,arg)    desc_spill_sprel_p(p,t,a,o,arg)
#define UNW_DEC_SPILL_SPREL(f,t,a,o,arg)  desc_spill_sprel_p(0,t,a,o,arg)
#define UNW_DEC_RESTORE_P(f,p,t,a,arg)          desc_restore_p(p,t,a,arg)
#define UNW_DEC_RESTORE(f,t,a,arg)        desc_restore_p(0,t,a,arg)

#include "unwind_decoder.c"


/* Unwind scripts. */

static inline unw_hash_index_t
hash (unsigned long ip)
{
#     define hashmagic  0x9e3779b97f4a7c16UL    /* based on (sqrt(5)/2-1)*2^64 */

      return (ip >> 4)*hashmagic >> (64 - UNW_LOG_HASH_SIZE);
#undef hashmagic
}

static inline long
cache_match (struct unw_script *script, unsigned long ip, unsigned long pr)
{
      read_lock(&script->lock);
      if (ip == script->ip && ((pr ^ script->pr_val) & script->pr_mask) == 0)
            /* keep the read lock... */
            return 1;
      read_unlock(&script->lock);
      return 0;
}

static inline struct unw_script *
script_lookup (struct unw_frame_info *info)
{
      struct unw_script *script = unw.cache + info->hint;
      unsigned short index;
      unsigned long ip, pr;

      if (UNW_DEBUG_ON(0))
            return NULL;      /* Always regenerate scripts in debug mode */

      STAT(++unw.stat.cache.lookups);

      ip = info->ip;
      pr = info->pr;

      if (cache_match(script, ip, pr)) {
            STAT(++unw.stat.cache.hinted_hits);
            return script;
      }

      index = unw.hash[hash(ip)];
      if (index >= UNW_CACHE_SIZE)
            return NULL;

      script = unw.cache + index;
      while (1) {
            if (cache_match(script, ip, pr)) {
                  /* update hint; no locking required as single-word writes are atomic */
                  STAT(++unw.stat.cache.normal_hits);
                  unw.cache[info->prev_script].hint = script - unw.cache;
                  return script;
            }
            if (script->coll_chain >= UNW_HASH_SIZE)
                  return NULL;
            script = unw.cache + script->coll_chain;
            STAT(++unw.stat.cache.collision_chain_traversals);
      }
}

/*
 * On returning, a write lock for the SCRIPT is still being held.
 */
static inline struct unw_script *
script_new (unsigned long ip)
{
      struct unw_script *script, *prev, *tmp;
      unw_hash_index_t index;
      unsigned short head;

      STAT(++unw.stat.script.news);

      /*
       * Can't (easily) use cmpxchg() here because of ABA problem
       * that is intrinsic in cmpxchg()...
       */
      head = unw.lru_head;
      script = unw.cache + head;
      unw.lru_head = script->lru_chain;

      /*
       * We'd deadlock here if we interrupted a thread that is holding a read lock on
       * script->lock.  Thus, if the write_trylock() fails, we simply bail out.  The
       * alternative would be to disable interrupts whenever we hold a read-lock, but
       * that seems silly.
       */
      if (!write_trylock(&script->lock))
            return NULL;

      /* re-insert script at the tail of the LRU chain: */
      unw.cache[unw.lru_tail].lru_chain = head;
      unw.lru_tail = head;

      /* remove the old script from the hash table (if it's there): */
      if (script->ip) {
            index = hash(script->ip);
            tmp = unw.cache + unw.hash[index];
            prev = NULL;
            while (1) {
                  if (tmp == script) {
                        if (prev)
                              prev->coll_chain = tmp->coll_chain;
                        else
                              unw.hash[index] = tmp->coll_chain;
                        break;
                  } else
                        prev = tmp;
                  if (tmp->coll_chain >= UNW_CACHE_SIZE)
                  /* old script wasn't in the hash-table */
                        break;
                  tmp = unw.cache + tmp->coll_chain;
            }
      }

      /* enter new script in the hash table */
      index = hash(ip);
      script->coll_chain = unw.hash[index];
      unw.hash[index] = script - unw.cache;

      script->ip = ip;  /* set new IP while we're holding the locks */

      STAT(if (script->coll_chain < UNW_CACHE_SIZE) ++unw.stat.script.collisions);

      script->flags = 0;
      script->hint = 0;
      script->count = 0;
      return script;
}

static void
script_finalize (struct unw_script *script, struct unw_state_record *sr)
{
      script->pr_mask = sr->pr_mask;
      script->pr_val = sr->pr_val;
      /*
       * We could down-grade our write-lock on script->lock here but
       * the rwlock API doesn't offer atomic lock downgrading, so
       * we'll just keep the write-lock and release it later when
       * we're done using the script.
       */
}

static inline void
script_emit (struct unw_script *script, struct unw_insn insn)
{
      if (script->count >= UNW_MAX_SCRIPT_LEN) {
            UNW_DPRINT(0, "unwind.%s: script exceeds maximum size of %u instructions!\n",
                  __FUNCTION__, UNW_MAX_SCRIPT_LEN);
            return;
      }
      script->insn[script->count++] = insn;
}

static inline void
emit_nat_info (struct unw_state_record *sr, int i, struct unw_script *script)
{
      struct unw_reg_info *r = sr->curr.reg + i;
      enum unw_insn_opcode opc;
      struct unw_insn insn;
      unsigned long val = 0;

      switch (r->where) {
            case UNW_WHERE_GR:
            if (r->val >= 32) {
                  /* register got spilled to a stacked register */
                  opc = UNW_INSN_SETNAT_TYPE;
                  val = UNW_NAT_REGSTK;
            } else
                  /* register got spilled to a scratch register */
                  opc = UNW_INSN_SETNAT_MEMSTK;
            break;

            case UNW_WHERE_FR:
            opc = UNW_INSN_SETNAT_TYPE;
            val = UNW_NAT_VAL;
            break;

            case UNW_WHERE_BR:
            opc = UNW_INSN_SETNAT_TYPE;
            val = UNW_NAT_NONE;
            break;

            case UNW_WHERE_PSPREL:
            case UNW_WHERE_SPREL:
            opc = UNW_INSN_SETNAT_MEMSTK;
            break;

            default:
            UNW_DPRINT(0, "unwind.%s: don't know how to emit nat info for where = %u\n",
                     __FUNCTION__, r->where);
            return;
      }
      insn.opc = opc;
      insn.dst = unw.preg_index[i];
      insn.val = val;
      script_emit(script, insn);
}

static void
compile_reg (struct unw_state_record *sr, int i, struct unw_script *script)
{
      struct unw_reg_info *r = sr->curr.reg + i;
      enum unw_insn_opcode opc;
      unsigned long val, rval;
      struct unw_insn insn;
      long need_nat_info;

      if (r->where == UNW_WHERE_NONE || r->when >= sr->when_target)
            return;

      opc = UNW_INSN_MOVE;
      val = rval = r->val;
      need_nat_info = (i >= UNW_REG_R4 && i <= UNW_REG_R7);

      switch (r->where) {
            case UNW_WHERE_GR:
            if (rval >= 32) {
                  opc = UNW_INSN_MOVE_STACKED;
                  val = rval - 32;
            } else if (rval >= 4 && rval <= 7) {
                  if (need_nat_info) {
                        opc = UNW_INSN_MOVE2;
                        need_nat_info = 0;
                  }
                  val = unw.preg_index[UNW_REG_R4 + (rval - 4)];
            } else if (rval == 0) {
                  opc = UNW_INSN_MOVE_CONST;
                  val = 0;
            } else {
                  /* register got spilled to a scratch register */
                  opc = UNW_INSN_MOVE_SCRATCH;
                  val = pt_regs_off(rval);
            }
            break;

            case UNW_WHERE_FR:
            if (rval <= 5)
                  val = unw.preg_index[UNW_REG_F2  + (rval -  2)];
            else if (rval >= 16 && rval <= 31)
                  val = unw.preg_index[UNW_REG_F16 + (rval - 16)];
            else {
                  opc = UNW_INSN_MOVE_SCRATCH;
                  if (rval <= 11)
                        val = offsetof(struct pt_regs, f6) + 16*(rval - 6);
                  else
                        UNW_DPRINT(0, "unwind.%s: kernel may not touch f%lu\n",
                                 __FUNCTION__, rval);
            }
            break;

            case UNW_WHERE_BR:
            if (rval >= 1 && rval <= 5)
                  val = unw.preg_index[UNW_REG_B1 + (rval - 1)];
            else {
                  opc = UNW_INSN_MOVE_SCRATCH;
                  if (rval == 0)
                        val = offsetof(struct pt_regs, b0);
                  else if (rval == 6)
                        val = offsetof(struct pt_regs, b6);
                  else
                        val = offsetof(struct pt_regs, b7);
            }
            break;

            case UNW_WHERE_SPREL:
            opc = UNW_INSN_ADD_SP;
            break;

            case UNW_WHERE_PSPREL:
            opc = UNW_INSN_ADD_PSP;
            break;

            default:
            UNW_DPRINT(0, "unwind%s: register %u has unexpected `where' value of %u\n",
                     __FUNCTION__, i, r->where);
            break;
      }
      insn.opc = opc;
      insn.dst = unw.preg_index[i];
      insn.val = val;
      script_emit(script, insn);
      if (need_nat_info)
            emit_nat_info(sr, i, script);

      if (i == UNW_REG_PSP) {
            /*
             * info->psp must contain the _value_ of the previous
             * sp, not it's save location.  We get this by
             * dereferencing the value we just stored in
             * info->psp:
             */
            insn.opc = UNW_INSN_LOAD;
            insn.dst = insn.val = unw.preg_index[UNW_REG_PSP];
            script_emit(script, insn);
      }
}

static inline const struct unw_table_entry *
lookup (struct unw_table *table, unsigned long rel_ip)
{
      const struct unw_table_entry *e = NULL;
      unsigned long lo, hi, mid;

      /* do a binary search for right entry: */
      for (lo = 0, hi = table->length; lo < hi; ) {
            mid = (lo + hi) / 2;
            e = &table->array[mid];
            if (rel_ip < e->start_offset)
                  hi = mid;
            else if (rel_ip >= e->end_offset)
                  lo = mid + 1;
            else
                  break;
      }
      if (rel_ip < e->start_offset || rel_ip >= e->end_offset)
            return NULL;
      return e;
}

/*
 * Build an unwind script that unwinds from state OLD_STATE to the
 * entrypoint of the function that called OLD_STATE.
 */
static inline struct unw_script *
build_script (struct unw_frame_info *info)
{
      const struct unw_table_entry *e = NULL;
      struct unw_script *script = NULL;
      struct unw_labeled_state *ls, *next;
      unsigned long ip = info->ip;
      struct unw_state_record sr;
      struct unw_table *table;
      struct unw_reg_info *r;
      struct unw_insn insn;
      u8 *dp, *desc_end;
      u64 hdr;
      int i;
      STAT(unsigned long start, parse_start;)

      STAT(++unw.stat.script.builds; start = ia64_get_itc());

      /* build state record */
      memset(&sr, 0, sizeof(sr));
      for (r = sr.curr.reg; r < sr.curr.reg + UNW_NUM_REGS; ++r)
            r->when = UNW_WHEN_NEVER;
      sr.pr_val = info->pr;

      UNW_DPRINT(3, "unwind.%s: ip 0x%lx\n", __FUNCTION__, ip);
      script = script_new(ip);
      if (!script) {
            UNW_DPRINT(0, "unwind.%s: failed to create unwind script\n",  __FUNCTION__);
            STAT(unw.stat.script.build_time += ia64_get_itc() - start);
            return NULL;
      }
      unw.cache[info->prev_script].hint = script - unw.cache;

      /* search the kernels and the modules' unwind tables for IP: */

      STAT(parse_start = ia64_get_itc());

      for (table = unw.tables; table; table = table->next) {
            if (ip >= table->start && ip < table->end) {
                  e = lookup(table, ip - table->segment_base);
                  break;
            }
      }
      if (!e) {
            /* no info, return default unwinder (leaf proc, no mem stack, no saved regs)  */
            UNW_DPRINT(1, "unwind.%s: no unwind info for ip=0x%lx (prev ip=0x%lx)\n",
                  __FUNCTION__, ip, unw.cache[info->prev_script].ip);
            sr.curr.reg[UNW_REG_RP].where = UNW_WHERE_BR;
            sr.curr.reg[UNW_REG_RP].when = -1;
            sr.curr.reg[UNW_REG_RP].val = 0;
            compile_reg(&sr, UNW_REG_RP, script);
            script_finalize(script, &sr);
            STAT(unw.stat.script.parse_time += ia64_get_itc() - parse_start);
            STAT(unw.stat.script.build_time += ia64_get_itc() - start);
            return script;
      }

      sr.when_target = (3*((ip & ~0xfUL) - (table->segment_base + e->start_offset))/16
                    + (ip & 0xfUL));
      hdr = *(u64 *) (table->segment_base + e->info_offset);
      dp =   (u8 *)  (table->segment_base + e->info_offset + 8);
      desc_end = dp + 8*UNW_LENGTH(hdr);

      while (!sr.done && dp < desc_end)
            dp = unw_decode(dp, sr.in_body, &sr);

      if (sr.when_target > sr.epilogue_start) {
            /*
             * sp has been restored and all values on the memory stack below
             * psp also have been restored.
             */
            sr.curr.reg[UNW_REG_PSP].val = 0;
            sr.curr.reg[UNW_REG_PSP].where = UNW_WHERE_NONE;
            sr.curr.reg[UNW_REG_PSP].when = UNW_WHEN_NEVER;
            for (r = sr.curr.reg; r < sr.curr.reg + UNW_NUM_REGS; ++r)
                  if ((r->where == UNW_WHERE_PSPREL && r->val <= 0x10)
                      || r->where == UNW_WHERE_SPREL)
                  {
                        r->val = 0;
                        r->where = UNW_WHERE_NONE;
                        r->when = UNW_WHEN_NEVER;
                  }
      }

      script->flags = sr.flags;

      /*
       * If RP did't get saved, generate entry for the return link
       * register.
       */
      if (sr.curr.reg[UNW_REG_RP].when >= sr.when_target) {
            sr.curr.reg[UNW_REG_RP].where = UNW_WHERE_BR;
            sr.curr.reg[UNW_REG_RP].when = -1;
            sr.curr.reg[UNW_REG_RP].val = sr.return_link_reg;
            UNW_DPRINT(1, "unwind.%s: using default for rp at ip=0x%lx where=%d val=0x%lx\n",
                     __FUNCTION__, ip, sr.curr.reg[UNW_REG_RP].where,
                     sr.curr.reg[UNW_REG_RP].val);
      }

#ifdef UNW_DEBUG
      UNW_DPRINT(1, "unwind.%s: state record for func 0x%lx, t=%u:\n",
            __FUNCTION__, table->segment_base + e->start_offset, sr.when_target);
      for (r = sr.curr.reg; r < sr.curr.reg + UNW_NUM_REGS; ++r) {
            if (r->where != UNW_WHERE_NONE || r->when != UNW_WHEN_NEVER) {
                  UNW_DPRINT(1, "  %s <- ", unw.preg_name[r - sr.curr.reg]);
                  switch (r->where) {
                        case UNW_WHERE_GR:     UNW_DPRINT(1, "r%lu", r->val); break;
                        case UNW_WHERE_FR:     UNW_DPRINT(1, "f%lu", r->val); break;
                        case UNW_WHERE_BR:     UNW_DPRINT(1, "b%lu", r->val); break;
                        case UNW_WHERE_SPREL:  UNW_DPRINT(1, "[sp+0x%lx]", r->val); break;
                        case UNW_WHERE_PSPREL: UNW_DPRINT(1, "[psp+0x%lx]", r->val); break;
                        case UNW_WHERE_NONE:
                        UNW_DPRINT(1, "%s+0x%lx", unw.preg_name[r - sr.curr.reg], r->val);
                        break;

                        default:
                        UNW_DPRINT(1, "BADWHERE(%d)", r->where);
                        break;
                  }
                  UNW_DPRINT(1, "\t\t%d\n", r->when);
            }
      }
#endif

      STAT(unw.stat.script.parse_time += ia64_get_itc() - parse_start);

      /* translate state record into unwinder instructions: */

      /*
       * First, set psp if we're dealing with a fixed-size frame;
       * subsequent instructions may depend on this value.
       */
      if (sr.when_target > sr.curr.reg[UNW_REG_PSP].when
          && (sr.curr.reg[UNW_REG_PSP].where == UNW_WHERE_NONE)
          && sr.curr.reg[UNW_REG_PSP].val != 0) {
            /* new psp is sp plus frame size */
            insn.opc = UNW_INSN_ADD;
            insn.dst = offsetof(struct unw_frame_info, psp)/8;
            insn.val = sr.curr.reg[UNW_REG_PSP].val;  /* frame size */
            script_emit(script, insn);
      }

      /* determine where the primary UNaT is: */
      if (sr.when_target < sr.curr.reg[UNW_REG_PRI_UNAT_GR].when)
            i = UNW_REG_PRI_UNAT_MEM;
      else if (sr.when_target < sr.curr.reg[UNW_REG_PRI_UNAT_MEM].when)
            i = UNW_REG_PRI_UNAT_GR;
      else if (sr.curr.reg[UNW_REG_PRI_UNAT_MEM].when > sr.curr.reg[UNW_REG_PRI_UNAT_GR].when)
            i = UNW_REG_PRI_UNAT_MEM;
      else
            i = UNW_REG_PRI_UNAT_GR;

      compile_reg(&sr, i, script);

      for (i = UNW_REG_BSP; i < UNW_NUM_REGS; ++i)
            compile_reg(&sr, i, script);

      /* free labeled register states & stack: */

      STAT(parse_start = ia64_get_itc());
      for (ls = sr.labeled_states; ls; ls = next) {
            next = ls->next;
            free_state_stack(&ls->saved_state);
            free_labeled_state(ls);
      }
      free_state_stack(&sr.curr);
      STAT(unw.stat.script.parse_time += ia64_get_itc() - parse_start);

      script_finalize(script, &sr);
      STAT(unw.stat.script.build_time += ia64_get_itc() - start);
      return script;
}

/*
 * Apply the unwinding actions represented by OPS and update SR to
 * reflect the state that existed upon entry to the function that this
 * unwinder represents.
 */
static inline void
run_script (struct unw_script *script, struct unw_frame_info *state)
{
      struct unw_insn *ip, *limit, next_insn;
      unsigned long opc, dst, val, off;
      unsigned long *s = (unsigned long *) state;
      STAT(unsigned long start;)

      STAT(++unw.stat.script.runs; start = ia64_get_itc());
      state->flags = script->flags;
      ip = script->insn;
      limit = script->insn + script->count;
      next_insn = *ip;

      while (ip++ < limit) {
            opc = next_insn.opc;
            dst = next_insn.dst;
            val = next_insn.val;
            next_insn = *ip;

        redo:
            switch (opc) {
                  case UNW_INSN_ADD:
                  s[dst] += val;
                  break;

                  case UNW_INSN_MOVE2:
                  if (!s[val])
                        goto lazy_init;
                  s[dst+1] = s[val+1];
                  s[dst] = s[val];
                  break;

                  case UNW_INSN_MOVE:
                  if (!s[val])
                        goto lazy_init;
                  s[dst] = s[val];
                  break;

                  case UNW_INSN_MOVE_SCRATCH:
                  if (state->pt) {
                        s[dst] = (unsigned long) get_scratch_regs(state) + val;
                  } else {
                        s[dst] = 0;
                        UNW_DPRINT(0, "unwind.%s: no state->pt, dst=%ld, val=%ld\n",
                                 __FUNCTION__, dst, val);
                  }
                  break;

                  case UNW_INSN_MOVE_CONST:
                  if (val == 0)
                        s[dst] = (unsigned long) &unw.r0;
                  else {
                        s[dst] = 0;
                        UNW_DPRINT(0, "unwind.%s: UNW_INSN_MOVE_CONST bad val=%ld\n",
                                 __FUNCTION__, val);
                  }
                  break;


                  case UNW_INSN_MOVE_STACKED:
                  s[dst] = (unsigned long) ia64_rse_skip_regs((unsigned long *)state->bsp,
                                                    val);
                  break;

                  case UNW_INSN_ADD_PSP:
                  s[dst] = state->psp + val;
                  break;

                  case UNW_INSN_ADD_SP:
                  s[dst] = state->sp + val;
                  break;

                  case UNW_INSN_SETNAT_MEMSTK:
                  if (!state->pri_unat_loc)
                        state->pri_unat_loc = &state->sw->caller_unat;
                  /* register off. is a multiple of 8, so the least 3 bits (type) are 0 */
                  s[dst+1] = ((unsigned long) state->pri_unat_loc - s[dst]) | UNW_NAT_MEMSTK;
                  break;

                  case UNW_INSN_SETNAT_TYPE:
                  s[dst+1] = val;
                  break;

                  case UNW_INSN_LOAD:
#ifdef UNW_DEBUG
                  if ((s[val] & (local_cpu_data->unimpl_va_mask | 0x7)) != 0
                      || s[val] < TASK_SIZE)
                  {
                        UNW_DPRINT(0, "unwind.%s: rejecting bad psp=0x%lx\n",
                                 __FUNCTION__, s[val]);
                        break;
                  }
#endif
                  s[dst] = *(unsigned long *) s[val];
                  break;
            }
      }
      STAT(unw.stat.script.run_time += ia64_get_itc() - start);
      return;

  lazy_init:
      off = unw.sw_off[val];
      s[val] = (unsigned long) state->sw + off;
      if (off >= offsetof(struct switch_stack, r4) && off <= offsetof(struct switch_stack, r7))
            /*
             * We're initializing a general register: init NaT info, too.  Note that
             * the offset is a multiple of 8 which gives us the 3 bits needed for
             * the type field.
             */
            s[val+1] = (offsetof(struct switch_stack, ar_unat) - off) | UNW_NAT_MEMSTK;
      goto redo;
}

static int
find_save_locs (struct unw_frame_info *info)
{
      int have_write_lock = 0;
      struct unw_script *scr;
      unsigned long flags = 0;

      if ((info->ip & (local_cpu_data->unimpl_va_mask | 0xf)) || info->ip < TASK_SIZE) {
            /* don't let obviously bad addresses pollute the cache */
            /* FIXME: should really be level 0 but it occurs too often. KAO */
            UNW_DPRINT(1, "unwind.%s: rejecting bad ip=0x%lx\n", __FUNCTION__, info->ip);
            info->rp_loc = NULL;
            return -1;
      }

      scr = script_lookup(info);
      if (!scr) {
            spin_lock_irqsave(&unw.lock, flags);
            scr = build_script(info);
            if (!scr) {
                  spin_unlock_irqrestore(&unw.lock, flags);
                  UNW_DPRINT(0,
                           "unwind.%s: failed to locate/build unwind script for ip %lx\n",
                           __FUNCTION__, info->ip);
                  return -1;
            }
            have_write_lock = 1;
      }
      info->hint = scr->hint;
      info->prev_script = scr - unw.cache;

      run_script(scr, info);

      if (have_write_lock) {
            write_unlock(&scr->lock);
            spin_unlock_irqrestore(&unw.lock, flags);
      } else
            read_unlock(&scr->lock);
      return 0;
}

static int
unw_valid(const struct unw_frame_info *info, unsigned long* p)
{
      unsigned long loc = (unsigned long)p;
      return (loc >= info->regstk.limit && loc < info->regstk.top) ||
             (loc >= info->memstk.top && loc < info->memstk.limit);
}

int
unw_unwind (struct unw_frame_info *info)
{
      unsigned long prev_ip, prev_sp, prev_bsp;
      unsigned long ip, pr, num_regs;
      STAT(unsigned long start, flags;)
      int retval;

      STAT(local_irq_save(flags); ++unw.stat.api.unwinds; start = ia64_get_itc());

      prev_ip = info->ip;
      prev_sp = info->sp;
      prev_bsp = info->bsp;

      /* validate the return IP pointer */
      if (!unw_valid(info, info->rp_loc)) {
            /* FIXME: should really be level 0 but it occurs too often. KAO */
            UNW_DPRINT(1, "unwind.%s: failed to locate return link (ip=0x%lx)!\n",
                     __FUNCTION__, info->ip);
            STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
            return -1;
      }
      /* restore the ip */
      ip = info->ip = *info->rp_loc;
      if (ip < GATE_ADDR) {
            UNW_DPRINT(2, "unwind.%s: reached user-space (ip=0x%lx)\n", __FUNCTION__, ip);
            STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
            return -1;
      }

      /* validate the previous stack frame pointer */
      if (!unw_valid(info, info->pfs_loc)) {
            UNW_DPRINT(0, "unwind.%s: failed to locate ar.pfs!\n", __FUNCTION__);
            STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
            return -1;
      }
      /* restore the cfm: */
      info->cfm_loc = info->pfs_loc;

      /* restore the bsp: */
      pr = info->pr;
      num_regs = 0;
      if ((info->flags & UNW_FLAG_INTERRUPT_FRAME)) {
            info->pt = info->sp + 16;
            if ((pr & (1UL << PRED_NON_SYSCALL)) != 0)
                  num_regs = *info->cfm_loc & 0x7f;         /* size of frame */
            info->pfs_loc =
                  (unsigned long *) (info->pt + offsetof(struct pt_regs, ar_pfs));
            UNW_DPRINT(3, "unwind.%s: interrupt_frame pt 0x%lx\n", __FUNCTION__, info->pt);
      } else
            num_regs = (*info->cfm_loc >> 7) & 0x7f;  /* size of locals */
      info->bsp = (unsigned long) ia64_rse_skip_regs((unsigned long *) info->bsp, -num_regs);
      if (info->bsp < info->regstk.limit || info->bsp > info->regstk.top) {
            UNW_DPRINT(0, "unwind.%s: bsp (0x%lx) out of range [0x%lx-0x%lx]\n",
                  __FUNCTION__, info->bsp, info->regstk.limit, info->regstk.top);
            STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
            return -1;
      }

      /* restore the sp: */
      info->sp = info->psp;
      if (info->sp < info->memstk.top || info->sp > info->memstk.limit) {
            UNW_DPRINT(0, "unwind.%s: sp (0x%lx) out of range [0x%lx-0x%lx]\n",
                  __FUNCTION__, info->sp, info->memstk.top, info->memstk.limit);
            STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
            return -1;
      }

      if (info->ip == prev_ip && info->sp == prev_sp && info->bsp == prev_bsp) {
            UNW_DPRINT(0, "unwind.%s: ip, sp, bsp unchanged; stopping here (ip=0x%lx)\n",
                     __FUNCTION__, ip);
            STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
            return -1;
      }

      /* as we unwind, the saved ar.unat becomes the primary unat: */
      info->pri_unat_loc = info->unat_loc;

      /* finally, restore the predicates: */
      unw_get_pr(info, &info->pr);

      retval = find_save_locs(info);
      STAT(unw.stat.api.unwind_time += ia64_get_itc() - start; local_irq_restore(flags));
      return retval;
}
EXPORT_SYMBOL(unw_unwind);

int
unw_unwind_to_user (struct unw_frame_info *info)
{
      unsigned long ip, sp, pr = info->pr;

      do {
            unw_get_sp(info, &sp);
            if ((long)((unsigned long)info->task + IA64_STK_OFFSET - sp)
                < IA64_PT_REGS_SIZE) {
                  UNW_DPRINT(0, "unwind.%s: ran off the top of the kernel stack\n",
                           __FUNCTION__);
                  break;
            }
            if (unw_is_intr_frame(info) &&
                (pr & (1UL << PRED_USER_STACK)))
                  return 0;
            if (unw_get_pr (info, &pr) < 0) {
                  unw_get_rp(info, &ip);
                  UNW_DPRINT(0, "unwind.%s: failed to read "
                           "predicate register (ip=0x%lx)\n",
                        __FUNCTION__, ip);
                  return -1;
            }
      } while (unw_unwind(info) >= 0);
      unw_get_ip(info, &ip);
      UNW_DPRINT(0, "unwind.%s: failed to unwind to user-level (ip=0x%lx)\n",
               __FUNCTION__, ip);
      return -1;
}
EXPORT_SYMBOL(unw_unwind_to_user);

static void
init_frame_info (struct unw_frame_info *info, struct task_struct *t,
             struct switch_stack *sw, unsigned long stktop)
{
      unsigned long rbslimit, rbstop, stklimit;
      STAT(unsigned long start, flags;)

      STAT(local_irq_save(flags); ++unw.stat.api.inits; start = ia64_get_itc());

      /*
       * Subtle stuff here: we _could_ unwind through the switch_stack frame but we
       * don't want to do that because it would be slow as each preserved register would
       * have to be processed.  Instead, what we do here is zero out the frame info and
       * start the unwind process at the function that created the switch_stack frame.
       * When a preserved value in switch_stack needs to be accessed, run_script() will
       * initialize the appropriate pointer on demand.
       */
      memset(info, 0, sizeof(*info));

      rbslimit = (unsigned long) t + IA64_RBS_OFFSET;
      stklimit = (unsigned long) t + IA64_STK_OFFSET;

      rbstop   = sw->ar_bspstore;
      if (rbstop > stklimit || rbstop < rbslimit)
            rbstop = rbslimit;

      if (stktop <= rbstop)
            stktop = rbstop;
      if (stktop > stklimit)
            stktop = stklimit;

      info->regstk.limit = rbslimit;
      info->regstk.top   = rbstop;
      info->memstk.limit = stklimit;
      info->memstk.top   = stktop;
      info->task = t;
      info->sw  = sw;
      info->sp = info->psp = stktop;
      info->pr = sw->pr;
      UNW_DPRINT(3, "unwind.%s:\n"
               "  task   0x%lx\n"
               "  rbs = [0x%lx-0x%lx)\n"
               "  stk = [0x%lx-0x%lx)\n"
               "  pr     0x%lx\n"
               "  sw     0x%lx\n"
               "  sp     0x%lx\n",
               __FUNCTION__, (unsigned long) t, rbslimit, rbstop, stktop, stklimit,
               info->pr, (unsigned long) info->sw, info->sp);
      STAT(unw.stat.api.init_time += ia64_get_itc() - start; local_irq_restore(flags));
}

void
unw_init_frame_info (struct unw_frame_info *info, struct task_struct *t, struct switch_stack *sw)
{
      unsigned long sol;

      init_frame_info(info, t, sw, (unsigned long) (sw + 1) - 16);
      info->cfm_loc = &sw->ar_pfs;
      sol = (*info->cfm_loc >> 7) & 0x7f;
      info->bsp = (unsigned long) ia64_rse_skip_regs((unsigned long *) info->regstk.top, -sol);
      info->ip = sw->b0;
      UNW_DPRINT(3, "unwind.%s:\n"
               "  bsp    0x%lx\n"
               "  sol    0x%lx\n"
               "  ip     0x%lx\n",
               __FUNCTION__, info->bsp, sol, info->ip);
      find_save_locs(info);
}

EXPORT_SYMBOL(unw_init_frame_info);

void
unw_init_from_blocked_task (struct unw_frame_info *info, struct task_struct *t)
{
      struct switch_stack *sw = (struct switch_stack *) (t->thread.ksp + 16);

      UNW_DPRINT(1, "unwind.%s\n", __FUNCTION__);
      unw_init_frame_info(info, t, sw);
}
EXPORT_SYMBOL(unw_init_from_blocked_task);

static void
init_unwind_table (struct unw_table *table, const char *name, unsigned long segment_base,
               unsigned long gp, const void *table_start, const void *table_end)
{
      const struct unw_table_entry *start = table_start, *end = table_end;

      table->name = name;
      table->segment_base = segment_base;
      table->gp = gp;
      table->start = segment_base + start[0].start_offset;
      table->end = segment_base + end[-1].end_offset;
      table->array = start;
      table->length = end - start;
}

void *
unw_add_unwind_table (const char *name, unsigned long segment_base, unsigned long gp,
                  const void *table_start, const void *table_end)
{
      const struct unw_table_entry *start = table_start, *end = table_end;
      struct unw_table *table;
      unsigned long flags;

      if (end - start <= 0) {
            UNW_DPRINT(0, "unwind.%s: ignoring attempt to insert empty unwind table\n",
                     __FUNCTION__);
            return NULL;
      }

      table = kmalloc(sizeof(*table), GFP_USER);
      if (!table)
            return NULL;

      init_unwind_table(table, name, segment_base, gp, table_start, table_end);

      spin_lock_irqsave(&unw.lock, flags);
      {
            /* keep kernel unwind table at the front (it's searched most commonly): */
            table->next = unw.tables->next;
            unw.tables->next = table;
      }
      spin_unlock_irqrestore(&unw.lock, flags);

      return table;
}

void
unw_remove_unwind_table (void *handle)
{
      struct unw_table *table, *prev;
      struct unw_script *tmp;
      unsigned long flags;
      long index;

      if (!handle) {
            UNW_DPRINT(0, "unwind.%s: ignoring attempt to remove non-existent unwind table\n",
                     __FUNCTION__);
            return;
      }

      table = handle;
      if (table == &unw.kernel_table) {
            UNW_DPRINT(0, "unwind.%s: sorry, freeing the kernel's unwind table is a "
                     "no-can-do!\n", __FUNCTION__);
            return;
      }

      spin_lock_irqsave(&unw.lock, flags);
      {
            /* first, delete the table: */

            for (prev = (struct unw_table *) &unw.tables; prev; prev = prev->next)
                  if (prev->next == table)
                        break;
            if (!prev) {
                  UNW_DPRINT(0, "unwind.%s: failed to find unwind table %p\n",
                           __FUNCTION__, (void *) table);
                  spin_unlock_irqrestore(&unw.lock, flags);
                  return;
            }
            prev->next = table->next;
      }
      spin_unlock_irqrestore(&unw.lock, flags);

      /* next, remove hash table entries for this table */

      for (index = 0; index <= UNW_HASH_SIZE; ++index) {
            tmp = unw.cache + unw.hash[index];
            if (unw.hash[index] >= UNW_CACHE_SIZE
                || tmp->ip < table->start || tmp->ip >= table->end)
                  continue;

            write_lock(&tmp->lock);
            {
                  if (tmp->ip >= table->start && tmp->ip < table->end) {
                        unw.hash[index] = tmp->coll_chain;
                        tmp->ip = 0;
                  }
            }
            write_unlock(&tmp->lock);
      }

      kfree(table);
}

static int __init
create_gate_table (void)
{
      const struct unw_table_entry *entry, *start, *end;
      unsigned long *lp, segbase = GATE_ADDR;
      size_t info_size, size;
      char *info;
      Elf64_Phdr *punw = NULL, *phdr = (Elf64_Phdr *) (GATE_ADDR + GATE_EHDR->e_phoff);
      int i;

      for (i = 0; i < GATE_EHDR->e_phnum; ++i, ++phdr)
            if (phdr->p_type == PT_IA_64_UNWIND) {
                  punw = phdr;
                  break;
            }

      if (!punw) {
            printk("%s: failed to find gate DSO's unwind table!\n", __FUNCTION__);
            return 0;
      }

      start = (const struct unw_table_entry *) punw->p_vaddr;
      end = (struct unw_table_entry *) ((char *) start + punw->p_memsz);
      size  = 0;

      unw_add_unwind_table("linux-gate.so", segbase, 0, start, end);

      for (entry = start; entry < end; ++entry)
            size += 3*8 + 8 + 8*UNW_LENGTH(*(u64 *) (segbase + entry->info_offset));
      size += 8;  /* reserve space for "end of table" marker */

      unw.gate_table = kmalloc(size, GFP_KERNEL);
      if (!unw.gate_table) {
            unw.gate_table_size = 0;
            printk(KERN_ERR "%s: unable to create unwind data for gate page!\n", __FUNCTION__);
            return 0;
      }
      unw.gate_table_size = size;

      lp = unw.gate_table;
      info = (char *) unw.gate_table + size;

      for (entry = start; entry < end; ++entry, lp += 3) {
            info_size = 8 + 8*UNW_LENGTH(*(u64 *) (segbase + entry->info_offset));
            info -= info_size;
            memcpy(info, (char *) segbase + entry->info_offset, info_size);

            lp[0] = segbase + entry->start_offset;          /* start */
            lp[1] = segbase + entry->end_offset;            /* end */
            lp[2] = info - (char *) unw.gate_table;         /* info */
      }
      *lp = 0;    /* end-of-table marker */
      return 0;
}

__initcall(create_gate_table);

void __init
unw_init (void)
{
      extern char __gp[];
      extern void unw_hash_index_t_is_too_narrow (void);
      long i, off;

      if (8*sizeof(unw_hash_index_t) < UNW_LOG_HASH_SIZE)
            unw_hash_index_t_is_too_narrow();

      unw.sw_off[unw.preg_index[UNW_REG_PRI_UNAT_GR]] = SW(CALLER_UNAT);
      unw.sw_off[unw.preg_index[UNW_REG_BSPSTORE]] = SW(AR_BSPSTORE);
      unw.sw_off[unw.preg_index[UNW_REG_PFS]] = SW(AR_PFS);
      unw.sw_off[unw.preg_index[UNW_REG_RP]] = SW(B0);
      unw.sw_off[unw.preg_index[UNW_REG_UNAT]] = SW(CALLER_UNAT);
      unw.sw_off[unw.preg_index[UNW_REG_PR]] = SW(PR);
      unw.sw_off[unw.preg_index[UNW_REG_LC]] = SW(AR_LC);
      unw.sw_off[unw.preg_index[UNW_REG_FPSR]] = SW(AR_FPSR);
      for (i = UNW_REG_R4, off = SW(R4); i <= UNW_REG_R7; ++i, off += 8)
            unw.sw_off[unw.preg_index[i]] = off;
      for (i = UNW_REG_B1, off = SW(B1); i <= UNW_REG_B5; ++i, off += 8)
            unw.sw_off[unw.preg_index[i]] = off;
      for (i = UNW_REG_F2, off = SW(F2); i <= UNW_REG_F5; ++i, off += 16)
            unw.sw_off[unw.preg_index[i]] = off;
      for (i = UNW_REG_F16, off = SW(F16); i <= UNW_REG_F31; ++i, off += 16)
            unw.sw_off[unw.preg_index[i]] = off;

      for (i = 0; i < UNW_CACHE_SIZE; ++i) {
            if (i > 0)
                  unw.cache[i].lru_chain = (i - 1);
            unw.cache[i].coll_chain = -1;
            rwlock_init(&unw.cache[i].lock);
      }
      unw.lru_head = UNW_CACHE_SIZE - 1;
      unw.lru_tail = 0;

      init_unwind_table(&unw.kernel_table, "kernel", KERNEL_START, (unsigned long) __gp,
                    __start_unwind, __end_unwind);
}

/*
 * DEPRECATED DEPRECATED DEPRECATED DEPRECATED DEPRECATED DEPRECATED DEPRECATED
 *
 *    This system call has been deprecated.  The new and improved way to get
 *    at the kernel's unwind info is via the gate DSO.  The address of the
 *    ELF header for this DSO is passed to user-level via AT_SYSINFO_EHDR.
 *
 * DEPRECATED DEPRECATED DEPRECATED DEPRECATED DEPRECATED DEPRECATED DEPRECATED
 *
 * This system call copies the unwind data into the buffer pointed to by BUF and returns
 * the size of the unwind data.  If BUF_SIZE is smaller than the size of the unwind data
 * or if BUF is NULL, nothing is copied, but the system call still returns the size of the
 * unwind data.
 *
 * The first portion of the unwind data contains an unwind table and rest contains the
 * associated unwind info (in no particular order).  The unwind table consists of a table
 * of entries of the form:
 *
 *    u64 start;  (64-bit address of start of function)
 *    u64 end;    (64-bit address of start of function)
 *    u64 info;   (BUF-relative offset to unwind info)
 *
 * The end of the unwind table is indicated by an entry with a START address of zero.
 *
 * Please see the IA-64 Software Conventions and Runtime Architecture manual for details
 * on the format of the unwind info.
 *
 * ERRORS
 *    EFAULT      BUF points outside your accessible address space.
 */
asmlinkage long
sys_getunwind (void __user *buf, size_t buf_size)
{
      if (buf && buf_size >= unw.gate_table_size)
            if (copy_to_user(buf, unw.gate_table, unw.gate_table_size) != 0)
                  return -EFAULT;
      return unw.gate_table_size;
}

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