--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/os/solaris/dtrace/libjvm_db.c	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,1500 @@
+/*
+ * Copyright 2003-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <gelf.h>
+
+#include "libjvm_db.h"
+#include "JvmOffsets.h"
+
+#define LIBJVM_SO "libjvm.so"
+
+#if defined(i386) || defined(__i386) || defined(__amd64)
+#ifdef COMPILER2
+#define X86_COMPILER2
+#endif /* COMPILER2 */
+#endif /* i386 */
+
+typedef struct {
+    short     vf_cnt; /* number of recognized java vframes */
+    short     bci;    /* current frame method byte code index */
+    int       line;   /* current frame method source line */
+    uint64_t new_fp; /* fp for the next frame */
+    uint64_t new_pc; /* pc for the next frame */
+    uint64_t new_sp; /* "raw" sp for the next frame (includes extension by interpreter/adapter */
+    char      locinf; /* indicates there is valid location info */
+} Jframe_t;
+
+int Jlookup_by_regs(jvm_agent_t* J, const prgregset_t regs, char *name,
+                    size_t size, Jframe_t *jframe);
+
+int main(int arg) { return arg; }
+
+static int debug = 0;
+
+static void failed(int err, const char * file, int line) {
+  if (debug) {
+    fprintf(stderr, "failed %d at %s:%d\n", err, file, line);
+  }
+}
+
+static void warn(const char * file, int line, const char * msg) {
+  if (debug) {
+    fprintf(stderr, "warning: %s at %s:%d\n", msg, file, line);
+  }
+}
+
+static void warn1(const char * file, int line, const char * msg, intptr_t arg1) {
+  if (debug) {
+    fprintf(stderr, "warning: ");
+    fprintf(stderr, msg, arg1);
+    fprintf(stderr, " at %s:%d\n", file, line);
+  }
+}
+
+#define CHECK_FAIL(err) \
+        if (err != PS_OK) { failed(err, __FILE__, __LINE__); goto fail; }
+#define WARN(msg)  warn(__FILE__, __LINE__, msg)
+#define WARN1(msg, arg1)  warn1(__FILE__, __LINE__, msg, arg1)
+
+typedef struct VMStructEntry {
+  const char * typeName;           /* The type name containing the given field (example: "Klass") */
+  const char * fieldName;          /* The field name within the type           (example: "_name") */
+  uint64_t address;                /* Address of field; only used for static fields */
+                                   /* ("offset" can not be reused because of apparent SparcWorks compiler bug */
+                                   /* in generation of initializer data) */
+} VMStructEntry;
+
+/* Prototyping inlined methods */
+
+int sprintf(char *s, const char *format, ...);
+
+#define SZ16  sizeof(int16_t)
+#define SZ32  sizeof(int32_t)
+
+#define COMP_METHOD_SIGN '*'
+
+#define MAX_VFRAMES_CNT 256
+
+typedef struct vframe {
+  uint64_t methodOop;
+  int32_t  sender_decode_offset;
+  int32_t  methodIdx;
+  int32_t  bci;
+  int32_t  line;
+} Vframe_t;
+
+typedef struct frame {
+  uintptr_t fp;
+  uintptr_t pc;
+  uintptr_t sp;
+  uintptr_t sender_sp; // The unextended sp of the caller
+} Frame_t;
+
+typedef struct Nmethod_t {
+  struct jvm_agent* J;
+  Jframe_t *jframe;
+
+  uint64_t nm;                  /* _nmethod */
+  uint64_t pc;
+  uint64_t pc_desc;
+
+  int32_t  orig_pc_offset;      /* _orig_pc_offset */
+  int32_t  instrs_beg;          /* _instructions_offset */
+  int32_t  instrs_end;
+  int32_t  deopt_beg;           /* _deoptimize_offset */
+  int32_t  scopes_data_beg;     /* _scopes_data_offset */
+  int32_t  scopes_data_end;
+  int32_t  oops_beg;            /* _oops_offset */
+  int32_t  oops_len;            /* _oops_length */
+  int32_t  scopes_pcs_beg;      /* _scopes_pcs_offset */
+  int32_t  scopes_pcs_end;
+
+  int      vf_cnt;
+  Vframe_t vframes[MAX_VFRAMES_CNT];
+} Nmethod_t;
+
+struct jvm_agent {
+  struct ps_prochandle* P;
+
+  uint64_t nmethod_vtbl;
+  uint64_t CodeBlob_vtbl;
+  uint64_t BufferBlob_vtbl;
+  uint64_t RuntimeStub_vtbl;
+
+  uint64_t Universe_methodKlassObj_address;
+  uint64_t CodeCache_heap_address;
+
+  /* Volatiles */
+  uint64_t Universe_methodKlassObj;
+  uint64_t CodeCache_low;
+  uint64_t CodeCache_high;
+  uint64_t CodeCache_segmap_low;
+  uint64_t CodeCache_segmap_high;
+
+  int32_t  SIZE_CodeCache_log2_segment;
+
+  uint64_t methodOopPtr;
+  uint64_t bcx;
+
+  Nmethod_t *N;                 /*Inlined methods support */
+  Frame_t   prev_fr;
+  Frame_t   curr_fr;
+};
+
+
+static int
+read_string(struct ps_prochandle *P,
+        char *buf,              /* caller's buffer */
+        size_t size,            /* upper limit on bytes to read */
+        uintptr_t addr)         /* address in process */
+{
+  int err = PS_OK;
+  while (size-- > 1 && err == PS_OK) {
+    err = ps_pread(P, addr, buf, 1);
+    if (*buf == '\0') {
+      return PS_OK;
+    }
+    addr += 1;
+    buf += 1;
+  }
+  return -1;
+}
+
+static int read_pointer(jvm_agent_t* J, uint64_t base, uint64_t* ptr) {
+  int err = -1;
+  uint32_t ptr32;
+
+  switch (DATA_MODEL) {
+  case PR_MODEL_LP64:
+    err = ps_pread(J->P, base, ptr, sizeof(uint64_t));
+    break;
+  case PR_MODEL_ILP32:
+    err = ps_pread(J->P, base, &ptr32, sizeof(uint32_t));
+    *ptr = ptr32;
+    break;
+  }
+
+  return err;
+}
+
+static int read_string_pointer(jvm_agent_t* J, uint64_t base, const char ** stringp) {
+  uint64_t ptr;
+  int err;
+  char buffer[1024];
+
+  *stringp = NULL;
+  err = read_pointer(J, base, &ptr);
+  CHECK_FAIL(err);
+  if (ptr != 0) {
+    err = read_string(J->P, buffer, sizeof(buffer), ptr);
+    CHECK_FAIL(err);
+    *stringp = strdup(buffer);
+  }
+  return PS_OK;
+
+ fail:
+  return err;
+}
+
+static int parse_vmstruct_entry(jvm_agent_t* J, uint64_t base, VMStructEntry* vmp) {
+  uint64_t ptr;
+  int err;
+
+  err = read_string_pointer(J, base + OFFSET_VMStructEntrytypeName, &vmp->typeName);
+  CHECK_FAIL(err);
+  err = read_string_pointer(J, base + OFFSET_VMStructEntryfieldName, &vmp->fieldName);
+  CHECK_FAIL(err);
+  err = read_pointer(J, base + OFFSET_VMStructEntryaddress, &vmp->address);
+  CHECK_FAIL(err);
+
+  return PS_OK;
+
+ fail:
+  if (vmp->typeName != NULL) free((void*)vmp->typeName);
+  if (vmp->fieldName != NULL) free((void*)vmp->fieldName);
+  return err;
+}
+
+static int parse_vmstructs(jvm_agent_t* J) {
+  VMStructEntry  vmVar;
+  VMStructEntry* vmp = &vmVar;
+  uint64_t gHotSpotVMStructs;
+  psaddr_t sym_addr;
+  uint64_t base;
+  int err;
+
+  err = ps_pglobal_lookup(J->P, LIBJVM_SO, "gHotSpotVMStructs", &sym_addr);
+  CHECK_FAIL(err);
+  err = read_pointer(J, sym_addr, &gHotSpotVMStructs);
+  CHECK_FAIL(err);
+  base = gHotSpotVMStructs;
+
+  err = PS_OK;
+  while (err == PS_OK) {
+    memset(vmp, 0, sizeof(VMStructEntry));
+    err = parse_vmstruct_entry(J, base, vmp);
+    if (err != PS_OK || vmp->typeName == NULL) {
+      break;
+    }
+
+    if (vmp->typeName[0] == 'C' && strcmp("CodeCache", vmp->typeName) == 0) {
+      if (strcmp("_heap", vmp->fieldName) == 0) {
+        err = read_pointer(J, vmp->address, &J->CodeCache_heap_address);
+      }
+    } else if (vmp->typeName[0] == 'U' && strcmp("Universe", vmp->typeName) == 0) {
+      if (strcmp("_methodKlassObj", vmp->fieldName) == 0) {
+        J->Universe_methodKlassObj_address = vmp->address;
+      }
+    }
+    CHECK_FAIL(err);
+
+    base += SIZE_VMStructEntry;
+    if (vmp->typeName != NULL) free((void*)vmp->typeName);
+    if (vmp->fieldName != NULL) free((void*)vmp->fieldName);
+  }
+
+  return PS_OK;
+
+ fail:
+  if (vmp->typeName != NULL) free((void*)vmp->typeName);
+  if (vmp->fieldName != NULL) free((void*)vmp->fieldName);
+  return -1;
+}
+
+static int read_volatiles(jvm_agent_t* J) {
+  uint64_t ptr;
+  int err;
+
+  err = read_pointer(J, J->Universe_methodKlassObj_address, &J->Universe_methodKlassObj);
+  CHECK_FAIL(err);
+  err = read_pointer(J, J->CodeCache_heap_address + OFFSET_CodeHeap_memory +
+                     OFFSET_VirtualSpace_low, &J->CodeCache_low);
+  CHECK_FAIL(err);
+  err = read_pointer(J, J->CodeCache_heap_address + OFFSET_CodeHeap_memory +
+                     OFFSET_VirtualSpace_high, &J->CodeCache_high);
+  CHECK_FAIL(err);
+  err = read_pointer(J, J->CodeCache_heap_address + OFFSET_CodeHeap_segmap +
+                     OFFSET_VirtualSpace_low, &J->CodeCache_segmap_low);
+  CHECK_FAIL(err);
+  err = read_pointer(J, J->CodeCache_heap_address + OFFSET_CodeHeap_segmap +
+                     OFFSET_VirtualSpace_high, &J->CodeCache_segmap_high);
+  CHECK_FAIL(err);
+
+  err = ps_pread(J->P, J->CodeCache_heap_address + OFFSET_CodeHeap_log2_segment_size,
+                 &J->SIZE_CodeCache_log2_segment, sizeof(J->SIZE_CodeCache_log2_segment));
+  CHECK_FAIL(err);
+
+  return PS_OK;
+
+ fail:
+  return err;
+}
+
+
+static int codecache_contains(jvm_agent_t* J, uint64_t ptr) {
+  /* make sure the code cache is up to date */
+  return (J->CodeCache_low <= ptr && ptr < J->CodeCache_high);
+}
+
+static uint64_t segment_for(jvm_agent_t* J, uint64_t p) {
+  return (p - J->CodeCache_low) >> J->SIZE_CodeCache_log2_segment;
+}
+
+static uint64_t block_at(jvm_agent_t* J, int i) {
+  return J->CodeCache_low + (i << J->SIZE_CodeCache_log2_segment);
+}
+
+static int find_start(jvm_agent_t* J, uint64_t ptr, uint64_t *startp) {
+  int err;
+
+  *startp = 0;
+  if (J->CodeCache_low <= ptr && ptr < J->CodeCache_high) {
+    int32_t used;
+    uint64_t segment = segment_for(J, ptr);
+    uint64_t block = J->CodeCache_segmap_low;
+    uint8_t tag;
+    err = ps_pread(J->P, block + segment, &tag, sizeof(tag));
+    CHECK_FAIL(err);
+    if (tag == 0xff)
+      return PS_OK;
+    while (tag > 0) {
+      err = ps_pread(J->P, block + segment, &tag, sizeof(tag));
+      CHECK_FAIL(err);
+      segment -= tag;
+    }
+    block = block_at(J, segment);
+    err = ps_pread(J->P, block + OFFSET_HeapBlockHeader_used, &used, sizeof(used));
+    CHECK_FAIL(err);
+    if (used) {
+      *startp = block + SIZE_HeapBlockHeader;
+    }
+  }
+  return PS_OK;
+
+ fail:
+  return -1;
+}
+
+static int find_symbol(jvm_agent_t* J, const char *name, uint64_t* valuep) {
+  psaddr_t sym_addr;
+  int err;
+
+  err = ps_pglobal_lookup(J->P, LIBJVM_SO, name, &sym_addr);
+  if (err != PS_OK) goto fail;
+  *valuep = sym_addr;
+  return PS_OK;
+
+ fail:
+  return err;
+}
+
+static int find_jlong_constant(jvm_agent_t* J, const char *name, uint64_t* valuep) {
+  psaddr_t sym_addr;
+  int err = ps_pglobal_lookup(J->P, LIBJVM_SO, name, &sym_addr);
+  if (err == PS_OK) {
+    err = ps_pread(J->P, sym_addr, valuep, sizeof(uint64_t));
+    return err;
+  }
+  *valuep = -1;
+  return -1;
+}
+
+jvm_agent_t *Jagent_create(struct ps_prochandle *P, int vers) {
+  jvm_agent_t* J;
+  int err;
+
+  if (vers != JVM_DB_VERSION) {
+    errno = ENOTSUP;
+    return NULL;
+  }
+
+  J = (jvm_agent_t*)calloc(sizeof(struct jvm_agent), 1);
+
+  debug = getenv("LIBJVMDB_DEBUG") != NULL;
+  if (debug) debug = 3;
+
+  if (debug) {
+      fprintf(stderr, "Jagent_create: debug=%d\n", debug);
+#ifdef X86_COMPILER2
+      fprintf(stderr, "Jagent_create: R_SP=%d, R_FP=%d, POINTER_SIZE=%d\n", R_SP, R_FP, POINTER_SIZE);
+#endif  /* X86_COMPILER2 */
+  }
+
+  J->P = P;
+
+  // Initialize the initial previous frame
+
+  J->prev_fr.fp = 0;
+  J->prev_fr.pc = 0;
+  J->prev_fr.sp = 0;
+  J->prev_fr.sender_sp = 0;
+
+  err = find_symbol(J, "__1cHnmethodG__vtbl_", &J->nmethod_vtbl);
+  CHECK_FAIL(err);
+  err = find_symbol(J, "__1cKBufferBlobG__vtbl_", &J->BufferBlob_vtbl);
+  if (err != PS_OK) J->BufferBlob_vtbl = 0;
+  err = find_symbol(J, "__1cICodeBlobG__vtbl_", &J->CodeBlob_vtbl);
+  CHECK_FAIL(err);
+  err = find_symbol(J, "__1cLRuntimeStubG__vtbl_", &J->RuntimeStub_vtbl);
+  CHECK_FAIL(err);
+
+  err = parse_vmstructs(J);
+  CHECK_FAIL(err);
+  err = read_volatiles(J);
+  CHECK_FAIL(err);
+
+  return J;
+
+ fail:
+  Jagent_destroy(J);
+  return NULL;
+}
+
+void Jagent_destroy(jvm_agent_t *J) {
+  if (J != NULL) {
+    free(J);
+  }
+}
+
+static int is_methodOop(jvm_agent_t* J, uint64_t methodOopPtr) {
+  uint64_t klass;
+  int err;
+  err = read_pointer(J, methodOopPtr + OFFSET_oopDesc_klass, &klass);
+  if (err != PS_OK) goto fail;
+  return klass == J->Universe_methodKlassObj;
+
+ fail:
+  return 0;
+}
+
+static int
+name_for_methodOop(jvm_agent_t* J, uint64_t methodOopPtr, char * result, size_t size)
+{
+  short nameIndex;
+  short signatureIndex;
+  uint64_t constantPool;
+  uint64_t constMethod;
+  uint64_t nameSymbol;
+  uint64_t signatureSymbol;
+  uint64_t klassPtr;
+  uint64_t klassSymbol;
+  short klassSymbolLength;
+  short nameSymbolLength;
+  short signatureSymbolLength;
+  char * nameString = NULL;
+  char * klassString = NULL;
+  char * signatureString = NULL;
+  int err;
+
+  err = read_pointer(J, methodOopPtr + OFFSET_methodOopDesc_constants, &constantPool);
+  CHECK_FAIL(err);
+  err = read_pointer(J, methodOopPtr + OFFSET_methodOopDesc_constMethod, &constMethod);
+  CHECK_FAIL(err);
+
+  /* To get name string */
+  err = ps_pread(J->P, constMethod + OFFSET_constMethodOopDesc_name_index, &nameIndex, 2);
+  CHECK_FAIL(err);
+  err = read_pointer(J, constantPool + nameIndex * POINTER_SIZE + SIZE_constantPoolOopDesc, &nameSymbol);
+  CHECK_FAIL(err);
+  err = ps_pread(J->P, nameSymbol + OFFSET_symbolOopDesc_length, &nameSymbolLength, 2);
+  CHECK_FAIL(err);
+  nameString = (char*)calloc(nameSymbolLength + 1, 1);
+  err = ps_pread(J->P, nameSymbol + OFFSET_symbolOopDesc_body, nameString, nameSymbolLength);
+  CHECK_FAIL(err);
+
+  /* To get signature string */
+  err = ps_pread(J->P, constMethod + OFFSET_constMethodOopDesc_signature_index, &signatureIndex, 2);
+  CHECK_FAIL(err);
+  err = read_pointer(J, constantPool + signatureIndex * POINTER_SIZE + SIZE_constantPoolOopDesc, &signatureSymbol);
+  CHECK_FAIL(err);
+  err = ps_pread(J->P, signatureSymbol + OFFSET_symbolOopDesc_length, &signatureSymbolLength, 2);
+  CHECK_FAIL(err);
+  signatureString = (char*)calloc(signatureSymbolLength + 1, 1);
+  err = ps_pread(J->P, signatureSymbol + OFFSET_symbolOopDesc_body, signatureString, signatureSymbolLength);
+  CHECK_FAIL(err);
+
+  /* To get klass string */
+  err = read_pointer(J, constantPool + OFFSET_constantPoolOopDesc_pool_holder, &klassPtr);
+  CHECK_FAIL(err);
+  err = read_pointer(J, klassPtr + OFFSET_Klass_name + SIZE_oopDesc, &klassSymbol);
+  CHECK_FAIL(err);
+  err = ps_pread(J->P, klassSymbol + OFFSET_symbolOopDesc_length, &klassSymbolLength, 2);
+  CHECK_FAIL(err);
+  klassString = (char*)calloc(klassSymbolLength + 1, 1);
+  err = ps_pread(J->P, klassSymbol + OFFSET_symbolOopDesc_body, klassString, klassSymbolLength);
+  CHECK_FAIL(err);
+
+  result[0] = '\0';
+  strncat(result, klassString, size);
+  size -= strlen(klassString);
+  strncat(result, ".", size);
+  size -= 1;
+  strncat(result, nameString, size);
+  size -= strlen(nameString);
+  strncat(result, signatureString, size);
+
+  if (nameString != NULL) free(nameString);
+  if (klassString != NULL) free(klassString);
+  if (signatureString != NULL) free(signatureString);
+
+  return PS_OK;
+
+ fail:
+  if (debug) {
+      fprintf(stderr, "name_for_methodOop: FAIL \n\n");
+  }
+  if (nameString != NULL) free(nameString);
+  if (klassString != NULL) free(klassString);
+  if (signatureString != NULL) free(signatureString);
+  return -1;
+}
+
+static int nmethod_info(Nmethod_t *N)
+{
+  jvm_agent_t *J = N->J;
+  uint64_t    nm = N->nm;
+  int32_t err;
+
+  if (debug > 2 )
+      fprintf(stderr, "\t nmethod_info: BEGIN \n");
+
+  /* Instructions */
+  err = ps_pread(J->P, nm + OFFSET_CodeBlob_instructions_offset, &N->instrs_beg, SZ32);
+  CHECK_FAIL(err);
+  err = ps_pread(J->P, nm + OFFSET_CodeBlob_data_offset, &N->instrs_end, SZ32);
+  CHECK_FAIL(err);
+  err = ps_pread(J->P, nm + OFFSET_nmethod_deoptimize_offset, &N->deopt_beg, SZ32);
+  CHECK_FAIL(err);
+  err = ps_pread(J->P, nm + OFFSET_nmethod_orig_pc_offset, &N->orig_pc_offset, SZ32);
+  CHECK_FAIL(err);
+
+  /* Oops */
+  err = ps_pread(J->P, nm + OFFSET_CodeBlob_oops_offset, &N->oops_beg, SZ32);
+  CHECK_FAIL(err);
+  err = ps_pread(J->P, nm + OFFSET_CodeBlob_oops_length, &N->oops_len, SZ32);
+  CHECK_FAIL(err);
+
+  /* scopes_pcs */
+  err = ps_pread(J->P, nm + OFFSET_nmethod_scopes_pcs_offset, &N->scopes_pcs_beg, SZ32);
+  CHECK_FAIL(err);
+  err = ps_pread(J->P, nm + OFFSET_nmethod_handler_table_offset, &N->scopes_pcs_end, SZ32);
+  CHECK_FAIL(err);
+
+  /* scopes_data */
+  err = ps_pread(J->P, nm + OFFSET_nmethod_scopes_data_offset, &N->scopes_data_beg, SZ32);
+  CHECK_FAIL(err);
+
+  if (debug > 2 ) {
+      N->scopes_data_end = N->scopes_pcs_beg;
+
+      fprintf(stderr, "\t nmethod_info: instrs_beg: %#x, instrs_end: %#x\n",
+                       N->instrs_beg, N->instrs_end);
+
+      fprintf(stderr, "\t nmethod_info: deopt_beg: %#x \n",
+                       N->deopt_beg);
+
+      fprintf(stderr, "\t nmethod_info: orig_pc_offset: %#x \n",
+                       N->orig_pc_offset);
+
+      fprintf(stderr, "\t nmethod_info: oops_beg: %#x, oops_len: %#x\n",
+                       N->oops_beg, N->oops_len);
+
+      fprintf(stderr, "\t nmethod_info: scopes_data_beg: %#x, scopes_data_end: %#x\n",
+                       N->scopes_data_beg, N->scopes_data_end);
+
+      fprintf(stderr, "\t nmethod_info: scopes_pcs_beg: %#x, scopes_pcs_end: %#x\n",
+                       N->scopes_pcs_beg, N->scopes_pcs_end);
+
+      fprintf(stderr, "\t nmethod_info: END \n\n");
+  }
+  return PS_OK;
+
+ fail:
+  return err;
+}
+
+static int
+raw_read_int(jvm_agent_t* J, uint64_t *buffer, int32_t *val)
+{
+  int shift = 0;
+  int value = 0;
+  uint8_t ch = 0;
+  int32_t  err;
+  int32_t sum;
+  // Constants for UNSIGNED5 coding of Pack200
+  // see compressedStream.hpp
+  enum {
+    lg_H = 6,
+    H = 1<<lg_H,
+    BitsPerByte = 8,
+    L = (1<<BitsPerByte)-H,
+  };
+  int i;
+
+  err = ps_pread(J->P, (*buffer)++, &ch, sizeof(uint8_t));
+  CHECK_FAIL(err);
+  if (debug > 2)
+      fprintf(stderr, "\t\t\t raw_read_int: *buffer: %#llx, ch: %#x\n", *buffer, ch);
+
+  sum = ch;
+  if ( sum >= L ) {
+    int32_t lg_H_i = lg_H;
+    // Read maximum of 5 total bytes (we've already read 1).
+    // See CompressedReadStream::read_int_mb
+    for ( i = 0;  i < 4; i++) {
+      err = ps_pread(J->P, (*buffer)++, &ch, sizeof(uint8_t));
+      CHECK_FAIL(err);
+      sum += ch << lg_H_i;
+      if (ch < L ) {
+        *val = sum;
+        return PS_OK;
+      }
+      lg_H_i += lg_H;
+    }
+  }
+  *val = sum;
+  return PS_OK;
+
+ fail:
+  return err;
+}
+
+static int
+read_pair(jvm_agent_t* J, uint64_t *buffer, int32_t *bci, int32_t *line)
+{
+  uint8_t next = 0;
+  int32_t bci_delta;
+  int32_t line_delta;
+  int32_t err;
+
+  if (debug > 2)
+      fprintf(stderr, "\t\t read_pair: BEGIN\n");
+
+  err = ps_pread(J->P, (*buffer)++, &next, sizeof(uint8_t));
+  CHECK_FAIL(err);
+
+  if (next == 0) {
+      if (debug > 2)
+          fprintf(stderr, "\t\t read_pair: END: next == 0\n");
+      return 1; /* stream terminated */
+  }
+  if (next == 0xFF) {
+      if (debug > 2)
+          fprintf(stderr, "\t\t read_pair: END: next == 0xFF\n");
+
+      /* Escape character, regular compression used */
+
+      err = raw_read_int(J, buffer, &bci_delta);
+      CHECK_FAIL(err);
+
+      err = raw_read_int(J, buffer, &line_delta);
+      CHECK_FAIL(err);
+
+      *bci  += bci_delta;
+      *line += line_delta;
+
+      if (debug > 2) {
+          fprintf(stderr, "\t\t read_pair: delta = (line %d: %d)\n",
+                          line_delta, bci_delta);
+          fprintf(stderr, "\t\t read_pair: unpack= (line %d: %d)\n",
+                          *line, *bci);
+      }
+  } else {
+      /* Single byte compression used */
+      *bci  += next >> 3;
+      *line += next & 0x7;
+      if (debug > 2) {
+          fprintf(stderr, "\t\t read_pair: delta = (line %d: %d)\n",
+                          next & 0x7, next >> 3);
+          fprintf(stderr, "\t\t read_pair: unpack= (line %d: %d)\n",
+                          *line, *bci);
+      }
+  }
+  if (debug > 2)
+      fprintf(stderr, "\t\t read_pair: END\n");
+  return PS_OK;
+
+ fail:
+  if (debug)
+      fprintf(stderr, "\t\t read_pair: FAIL\n");
+  return err;
+}
+
+static int
+line_number_from_bci(jvm_agent_t* J, Vframe_t *vf)
+{
+  uint64_t buffer;
+  uint16_t code_size;
+  uint64_t code_end_delta;
+  uint64_t constMethod;
+  int8_t   access_flags;
+  int32_t  best_bci    = 0;
+  int32_t  stream_bci  = 0;
+  int32_t  stream_line = 0;
+  int32_t  err;
+
+  if (debug > 2) {
+      char name[256];
+      err = name_for_methodOop(J, vf->methodOop, name, 256);
+      CHECK_FAIL(err);
+      fprintf(stderr, "\t line_number_from_bci: BEGIN, method name: %s, targ bci: %d\n",
+                       name, vf->bci);
+  }
+
+  err = read_pointer(J, vf->methodOop + OFFSET_methodOopDesc_constMethod, &constMethod);
+  CHECK_FAIL(err);
+
+  vf->line = 0;
+  err = ps_pread(J->P, constMethod + OFFSET_constMethodOopDesc_flags, &access_flags, sizeof(int8_t));
+  CHECK_FAIL(err);
+
+  if (!(access_flags & constMethodOopDesc_has_linenumber_table)) {
+      if (debug > 2)
+          fprintf(stderr, "\t line_number_from_bci: END: !HAS_LINE_NUMBER_TABLE \n\n");
+      return PS_OK;
+  }
+
+  /*  The line numbers are a short array of 2-tuples [start_pc, line_number].
+   *  Not necessarily sorted and not necessarily one-to-one.
+   */
+
+  err = ps_pread(J->P, constMethod + OFFSET_constMethodOopDesc_code_size, &code_size, SZ16);
+  CHECK_FAIL(err);
+
+  /* inlined_table_start() */
+  code_end_delta = (uint64_t) (access_flags & AccessFlags_NATIVE) ? 2*POINTER_SIZE : 0;
+  buffer = constMethod + (uint64_t) SIZE_constMethodOopDesc + (uint64_t) code_size + code_end_delta;
+
+  if (debug > 2) {
+      fprintf(stderr, "\t\t line_number_from_bci: methodOop: %#llx, native: %d\n",
+                      vf->methodOop, (access_flags & AccessFlags_NATIVE));
+      fprintf(stderr, "\t\t line_number_from_bci: buffer: %#llx, code_size: %d\n",
+                      buffer, (int) code_size);
+  }
+
+  while (read_pair(J, &buffer, &stream_bci, &stream_line) == 0) {
+      if (stream_bci == vf->bci) {
+          /* perfect match */
+          if (debug > 2)
+              fprintf(stderr, "\t line_number_from_bci: END: exact line: %ld \n\n", vf->line);
+          vf->line = stream_line;
+          return PS_OK;
+      } else {
+          /* update best_bci/line */
+          if (stream_bci < vf->bci && stream_bci >= best_bci) {
+              best_bci = stream_bci;
+              vf->line = stream_line;
+              if (debug > 2) {
+                  fprintf(stderr, "\t line_number_from_bci: best_bci: %ld, best_line: %ld\n",
+                                   best_bci, vf->line);
+              }
+          }
+      }
+  }
+  if (debug > 2)
+      fprintf(stderr, "\t line_number_from_bci: END: line: %ld \n\n", vf->line);
+  return PS_OK;
+
+ fail:
+  if (debug)
+      fprintf(stderr, "\t line_number_from_bci: FAIL\n");
+  return err;
+}
+
+static int
+get_real_pc(Nmethod_t *N, uint64_t pc_desc, uint64_t *real_pc)
+{
+  int32_t pc_offset;
+  int32_t err;
+
+  err = ps_pread(N->J->P, pc_desc + OFFSET_PcDesc_pc_offset, &pc_offset, SZ32);
+  CHECK_FAIL(err);
+
+  *real_pc = N->nm + N->instrs_beg + pc_offset;
+  if (debug > 2) {
+      fprintf(stderr, "\t\t get_real_pc: pc_offset: %lx, real_pc: %llx\n",
+                       pc_offset, *real_pc);
+  }
+  return PS_OK;
+
+ fail:
+  return err;
+}
+
+/* Finds a PcDesc with real-pc equal to N->pc */
+static int pc_desc_at(Nmethod_t *N)
+{
+  uint64_t pc_diff;
+  int32_t offs;
+  int32_t err;
+
+  if (debug > 2)
+      fprintf(stderr, "\t pc_desc_at: BEGIN\n");
+
+  N->vf_cnt  = 0;
+  N->pc_desc = 0;
+
+  for (offs = N->scopes_pcs_beg; offs < N->scopes_pcs_end; offs += SIZE_PcDesc) {
+      uint64_t pd;
+      uint64_t best_pc_diff = 16;       /* some approximation */
+      uint64_t real_pc = 0;
+
+      pd = N->nm + offs;
+      err = get_real_pc(N, pd, &real_pc);
+      CHECK_FAIL(err);
+
+      pc_diff = real_pc - N->pc;
+
+      /* In general, this fragment should work */
+      if (pc_diff == 0) {
+          N->pc_desc = pd;
+          if (debug) {
+            fprintf(stderr, "\t pc_desc_at: END: pc_desc: FOUND: %#lx \n\n", pd);
+          }
+          return PS_OK;
+      }
+      /* This fragment is to be able to find out an appropriate
+       * pc_desc entry even if pc_desc info is inaccurate.
+       */
+      if (best_pc_diff > pc_diff && pc_diff > 0) {
+          best_pc_diff = pc_diff;
+          N->pc_desc = pd;
+      }
+  }
+  if (debug) {
+      fprintf(stderr, "\t pc_desc_at: END: pc_desc NOT FOUND");
+      if (pc_diff < 20)
+          fprintf(stderr, ", best pc_diff: %d\n\n", pc_diff);
+      else
+          fprintf(stderr, "\n\n");
+  }
+  return PS_OK;
+
+ fail:
+  return err;
+}
+
+static int
+scope_desc_at(Nmethod_t *N, int32_t decode_offset, Vframe_t *vf)
+{
+  uint64_t buffer;
+  int32_t  err;
+
+  if (debug > 2) {
+      fprintf(stderr, "\t\t scope_desc_at: BEGIN \n");
+  }
+
+  buffer = N->nm + N->scopes_data_beg + decode_offset;
+
+  err = raw_read_int(N->J, &buffer, &vf->sender_decode_offset);
+  CHECK_FAIL(err);
+
+  err = raw_read_int(N->J, &buffer, &vf->methodIdx);
+  CHECK_FAIL(err);
+
+  err = raw_read_int(N->J, &buffer, &vf->bci);
+  CHECK_FAIL(err);
+
+  if (debug > 2) {
+      fprintf(stderr, "\t\t scope_desc_at: sender_decode_offset: %#x\n",
+                      vf->sender_decode_offset);
+      fprintf(stderr, "\t\t scope_desc_at: methodIdx: %d\n", vf->methodIdx);
+      fprintf(stderr, "\t\t scope_desc_at: bci: %d\n", vf->bci);
+
+      fprintf(stderr, "\t\t scope_desc_at: END \n\n");
+  }
+  return PS_OK;
+
+ fail:
+  return err;
+}
+
+static int
+scopeDesc_chain(Nmethod_t *N)
+{
+  int32_t decode_offset = 0;
+  int32_t err;
+
+  if (debug > 2)
+      fprintf(stderr, "\t scopeDesc_chain: BEGIN\n");
+
+  err = ps_pread(N->J->P, N->pc_desc + OFFSET_PcDesc_scope_decode_offset,
+                 &decode_offset, SZ32);
+  CHECK_FAIL(err);
+
+  while (decode_offset > 0) {
+      if (debug > 2)
+          fprintf(stderr, "\t scopeDesc_chain: decode_offset: %#x\n", decode_offset);
+
+      Vframe_t *vf = &N->vframes[N->vf_cnt];
+
+      err = scope_desc_at(N, decode_offset, vf);
+      CHECK_FAIL(err);
+
+      if (vf->methodIdx > N->oops_len) {
+          fprintf(stderr, "\t scopeDesc_chain: (methodIdx > oops_len) !\n");
+          return -1;
+      }
+      err = read_pointer(N->J, N->nm + N->oops_beg + (vf->methodIdx-1)*POINTER_SIZE,
+                               &vf->methodOop);
+      CHECK_FAIL(err);
+
+      if (vf->methodOop) {
+          N->vf_cnt++;
+          err = line_number_from_bci(N->J, vf);
+          CHECK_FAIL(err);
+          if (debug > 2) {
+              fprintf(stderr, "\t scopeDesc_chain: methodOop: %#8llx, line: %ld\n",
+                              vf->methodOop, vf->line);
+          }
+      }
+      decode_offset = vf->sender_decode_offset;
+  }
+  if (debug > 2)
+      fprintf(stderr, "\t scopeDesc_chain: END \n\n");
+  return PS_OK;
+
+ fail:
+  if (debug)
+      fprintf(stderr, "\t scopeDesc_chain: FAIL \n\n");
+  return err;
+}
+
+
+static int
+name_for_nmethod(jvm_agent_t* J,
+                 uint64_t nm,
+                 uint64_t pc,
+                 uint64_t methodOop,
+                 char *result,
+                 size_t size,
+                 Jframe_t *jframe
+) {
+  Nmethod_t *N;
+  Vframe_t *vf;
+  int32_t err;
+  int deoptimized = 0;
+
+  if (debug) {
+      fprintf(stderr, "name_for_nmethod: BEGIN: nmethod: %#llx, pc: %#llx\n", nm, pc);
+  }
+  if (J->N == NULL) {
+    J->N = (Nmethod_t *) malloc(sizeof(Nmethod_t));
+  }
+  memset(J->N, 0, sizeof(Nmethod_t));   /* Initial stat: all values are zeros */
+  N     = J->N;
+  N->J  = J;
+  N->nm = nm;
+  N->pc = pc;
+  N->jframe = jframe;
+
+  err = nmethod_info(N);
+  CHECK_FAIL(err);
+  if (debug) {
+      fprintf(stderr, "name_for_nmethod: pc: %#llx, deopt_pc:  %#llx\n",
+              pc, N->nm + N->deopt_beg);
+  }
+
+  /* check for a deoptimized frame */
+  if ( pc == N->nm + N->deopt_beg) {
+    uint64_t base;
+    if (debug) {
+        fprintf(stderr, "name_for_nmethod: found deoptimized frame\n");
+    }
+    if (J->prev_fr.sender_sp != 0) {
+      base = J->prev_fr.sender_sp + N->orig_pc_offset;
+    } else {
+      base = J->curr_fr.sp + N->orig_pc_offset;
+    }
+    err = read_pointer(J, base, &N->pc);
+    CHECK_FAIL(err);
+    if (debug) {
+        fprintf(stderr, "name_for_nmethod: found deoptimized frame converting pc from %#8llx to %#8llx\n",
+        pc,  N->pc);
+    }
+    deoptimized = 1;
+  }
+
+  err = pc_desc_at(N);
+  CHECK_FAIL(err);
+
+  if (N->pc_desc > 0) {
+      jframe->locinf = 1;
+      err = scopeDesc_chain(N);
+      CHECK_FAIL(err);
+  }
+  result[0] = COMP_METHOD_SIGN;
+  vf = &N->vframes[0];
+  if (N->vf_cnt > 0) {
+      jframe->vf_cnt = N->vf_cnt;
+      jframe->bci  = vf->bci;
+      jframe->line = vf->line;
+      err = name_for_methodOop(J, N->vframes[0].methodOop, result+1, size-1);
+      CHECK_FAIL(err);
+  } else {
+      err = name_for_methodOop(J, methodOop, result+1, size-1);
+      CHECK_FAIL(err);
+  }
+  if (deoptimized) {
+    strncat(result + 1, " [deoptimized frame]; ", size-1);
+  } else {
+    strncat(result + 1, " [compiled] ", size-1);
+  }
+  if (debug)
+      fprintf(stderr, "name_for_nmethod: END: method name: %s, vf_cnt: %d\n\n",
+                      result, N->vf_cnt);
+  return PS_OK;
+
+ fail:
+  if (debug)
+      fprintf(stderr, "name_for_nmethod: FAIL \n\n");
+  return err;
+}
+
+int is_bci(intptr_t bcx) {
+  switch (DATA_MODEL) {
+  case PR_MODEL_LP64:
+    return ((uintptr_t) bcx) <= ((uintptr_t) MAX_METHOD_CODE_SIZE) ;
+  case PR_MODEL_ILP32:
+  default:
+    return 0 <= bcx && bcx <= MAX_METHOD_CODE_SIZE;
+  }
+}
+
+static int
+name_for_imethod(jvm_agent_t* J,
+                 uint64_t bcx,
+                 uint64_t methodOop,
+                 char *result,
+                 size_t size,
+                 Jframe_t *jframe
+) {
+  uint64_t bci;
+  uint64_t constMethod;
+  Vframe_t vframe = {0};
+  Vframe_t *vf = &vframe;
+  int32_t   err;
+
+  err = read_pointer(J, methodOop + OFFSET_methodOopDesc_constMethod, &constMethod);
+  CHECK_FAIL(err);
+
+  bci = is_bci(bcx) ? bcx : bcx - (constMethod + (uint64_t) SIZE_constMethodOopDesc);
+
+  if (debug)
+      fprintf(stderr, "\t name_for_imethod: BEGIN: methodOop: %#llx\n", methodOop);
+
+  err = name_for_methodOop(J, methodOop, result, size);
+  CHECK_FAIL(err);
+  if (debug)
+      fprintf(stderr, "\t name_for_imethod: method name: %s\n", result);
+
+  if (bci > 0) {
+      vf->methodOop = methodOop;
+      vf->bci       = bci;
+      err = line_number_from_bci(J, vf);
+      CHECK_FAIL(err);
+  }
+  jframe->bci  = vf->bci;
+  jframe->line = vf->line;
+  jframe->locinf = 1;
+
+  if (debug) {
+      fprintf(stderr, "\t name_for_imethod: END: bci: %d, line: %d\n\n",
+                      vf->bci, vf->line);
+  }
+  return PS_OK;
+
+ fail:
+  if (debug)
+      fprintf(stderr, "\t name_for_imethod: FAIL\n");
+  return err;
+}
+
+static int
+name_for_codecache(jvm_agent_t* J, uint64_t fp, uint64_t pc, char * result,
+                   size_t size, Jframe_t *jframe, int* is_interpreted)
+{
+  uint64_t start;
+  uint64_t vtbl;
+  int32_t err;
+  *is_interpreted = 0;
+
+  result[0] = '\0';
+
+  err = find_start(J, pc, &start);
+  CHECK_FAIL(err);
+
+  err = read_pointer(J, start, &vtbl);
+  CHECK_FAIL(err);
+
+  if (vtbl == J->nmethod_vtbl) {
+    uint64_t methodOop;
+
+    err = read_pointer(J, start + OFFSET_nmethod_method, &methodOop);
+    CHECK_FAIL(err);
+
+    if (debug) {
+        fprintf(stderr, "name_for_codecache: start: %#8llx, pc: %#8llx, methodOop: %#8llx \n",
+                        start, pc, methodOop);
+    }
+    err = name_for_nmethod(J, start, pc, methodOop, result, size, jframe);
+    CHECK_FAIL(err);
+  } else if (vtbl == J->BufferBlob_vtbl) {
+    const char * name;
+
+    err = read_string_pointer(J, start + OFFSET_CodeBlob_name, &name);
+
+    /*
+     * Temporary usage of string "Interpreter".
+     * We need some other way to distinguish "StubRoutines"
+     * and regular interpreted frames.
+     */
+    if (err == PS_OK && strncmp(name, "Interpreter", 11) == 0) {
+      *is_interpreted = 1;
+      if (is_methodOop(J, J->methodOopPtr)) {
+        return name_for_imethod(J, J->bcx, J->methodOopPtr, result, size, jframe);
+      }
+    }
+
+    if (err == PS_OK) {
+      strncpy(result, name, size);
+      free((void*)name);
+    } else {
+      strncpy(result, "<unknown BufferBlob>", size);
+    }
+    /* return PS_OK; */
+  } else {
+    const char * name;
+
+    err = read_string_pointer(J, start + OFFSET_CodeBlob_name, &name);
+    if (err == PS_OK) {
+      strncpy(result, name, size);
+      free((void*)name);
+    } else {
+      strncpy(result, "<unknown CodeBlob>", size);
+      WARN1("unknown CodeBlob: vtbl = 0x%x", vtbl);
+    }
+  }
+  result[size-1] = '\0';
+
+#ifdef X86_COMPILER2
+  if (vtbl != J->RuntimeStub_vtbl) {
+    uint64_t trial_pc;
+    int frame_size;
+    err = ps_pread(J->P, start + OFFSET_CodeBlob_frame_size,
+                         &frame_size, SZ32);
+    CHECK_FAIL(err);
+
+    // frame_size is in words, we want bytes.
+    frame_size *= POINTER_SIZE; /* word => byte conversion */
+
+    /*
+      Because c2 doesn't use FP as a framepointer the value of sp/fp we receive
+      in the initial entry to a set of stack frames containing server frames
+      will pretty much be nonsense. We can detect that nonsense by looking to
+      see if the PC we received is correct if we look at the expected storage
+      location in relation to the FP (ie. POINTER_SIZE(FP) )
+    */
+
+    err = read_pointer(J, fp + POINTER_SIZE , &trial_pc);
+    if ( (err != PS_OK || trial_pc != pc) && frame_size > 0 ) {
+      // Either we couldn't even read at the "fp" or the pc didn't match
+      // both are sure clues that the fp is bogus. We no search the stack
+      // for a reasonable number of words trying to find the bogus fp
+      // and the current pc in adjacent words. The we will be able to
+      // deduce an approximation of the frame pointer and actually get
+      // the correct stack pointer. Which we can then unwind for the
+      // next frame.
+      int i;
+      uint64_t check;
+      uint64_t base = J->curr_fr.sp;
+      uint64_t prev_fp = 0;
+      for ( i = 0; i < frame_size * 5 ; i++, base += POINTER_SIZE ) {
+        err = read_pointer(J, base , &check);
+        CHECK_FAIL(err);
+        if (check == fp) {
+          base += POINTER_SIZE;
+          err = read_pointer(J, base , &check);
+          CHECK_FAIL(err);
+          if (check == pc) {
+            if (debug) {
+              fprintf(stderr, "name_for_codecache: found matching fp/pc combo at 0x%llx\n", base - POINTER_SIZE);
+            }
+            prev_fp = base - 2 * POINTER_SIZE;
+            break;
+          }
+        }
+      }
+      if ( prev_fp != 0 ) {
+        // real_sp is the sp we should have received for this frame
+        uint64_t real_sp = prev_fp + 2 * POINTER_SIZE;
+        // +POINTER_SIZE because callee owns the return address so caller's sp is +1 word
+        jframe->new_sp = real_sp + frame_size + POINTER_SIZE;
+        err = read_pointer(J, jframe->new_sp - POINTER_SIZE , &jframe->new_pc);
+        CHECK_FAIL(err);
+        err = read_pointer(J, jframe->new_sp - 2*POINTER_SIZE, &jframe->new_fp);
+        CHECK_FAIL(err);
+        return PS_OK;
+      }
+    }
+
+    /* A prototype to workaround FP absence */
+    /*
+     * frame_size can be 0 for StubRoutines (1) frame.
+     * In this case it should work with fp as usual.
+     */
+    if (frame_size > 0) {
+      jframe->new_fp = J->prev_fr.fp + frame_size;
+      jframe->new_sp = jframe->new_fp + 2 * POINTER_SIZE;
+    } else {
+      memset(&J->curr_fr, 0, sizeof(Frame_t));
+      err = read_pointer(J,  fp, &jframe->new_fp);
+      CHECK_FAIL(err);
+
+      err = read_pointer(J,  jframe->new_fp + POINTER_SIZE,  &jframe->new_pc);
+      CHECK_FAIL(err);
+    }
+    if (debug) {
+      fprintf(stderr, "name_for_codecache: %s, frame_size=%#lx\n",
+                       result, frame_size);
+      fprintf(stderr, "name_for_codecache: prev_fr.fp=%#lx, fp=%#lx\n",
+                       J->prev_fr.fp, jframe->new_fp);
+    }
+  }
+#endif /* X86_COMPILER2 */
+
+  return PS_OK;
+
+ fail:
+  return err;
+}
+
+int Jget_vframe(jvm_agent_t* J, int vframe_no,
+                char *name, size_t size, Jframe_t *jframe)
+{
+  Nmethod_t *N = J->N;
+  Vframe_t  *vf;
+  int32_t   err;
+
+  if (vframe_no >= N->vf_cnt) {
+     (void) sprintf(name, "Wrong inlinedMethod%1d()", vframe_no);
+     return -1;
+  }
+  vf = N->vframes + vframe_no;
+  name[0] = COMP_METHOD_SIGN;
+  err = name_for_methodOop(J, vf->methodOop, name + 1, size);
+  CHECK_FAIL(err);
+
+  jframe->bci = vf->bci;
+  jframe->line = vf->line;
+  if (debug) {
+      fprintf(stderr, "\t Jget_vframe: method name: %s, line: %ld\n",
+                       name, vf->line);
+  }
+  return PS_OK;
+
+ fail:
+  if (debug) {
+      fprintf(stderr, "\t Jget_vframe: FAIL\n");
+  }
+  return err;
+}
+
+#define MAX_SYM_SIZE 256
+
+int Jlookup_by_regs(jvm_agent_t* J, const prgregset_t regs, char *name,
+                    size_t size, Jframe_t *jframe) {
+  uintptr_t fp;
+  uintptr_t pc;
+  /* arguments given to read_pointer need to be worst case sized */
+  uint64_t methodOopPtr = 0;
+  uint64_t sender_sp;
+  uint64_t bcx = 0;
+  int is_interpreted = 0;
+  int result = PS_OK;
+  int err = PS_OK;
+
+  if (J == NULL) {
+    return -1;
+  }
+
+  jframe->vf_cnt = 1;
+  jframe->new_fp = 0;
+  jframe->new_pc = 0;
+  jframe->line   = 0;
+  jframe->bci    = 0;
+  jframe->locinf = 0;
+
+  read_volatiles(J);
+  pc = (uintptr_t) regs[R_PC];
+  J->curr_fr.pc = pc;
+  J->curr_fr.fp = regs[R_FP];
+  J->curr_fr.sp = regs[R_SP];
+
+  if (debug)
+      fprintf(stderr, "Jlookup_by_regs: BEGINs: fp=%#lx, pc=%#lx\n", regs[R_FP], pc);
+
+#if defined(sparc) || defined(__sparc)
+    /* The following workaround is for SPARC. CALL instruction occupates 8 bytes.
+     * In the pcDesc structure return pc offset is recorded for CALL instructions.
+     * regs[R_PC] contains a CALL instruction pc offset.
+     */
+    pc += 8;
+    bcx          = (uintptr_t) regs[R_L1];
+    methodOopPtr = (uintptr_t) regs[R_L2];
+    sender_sp = regs[R_I5];
+    if (debug > 2) {
+        fprintf(stderr, "\nregs[R_I1]=%lx, regs[R_I2]=%lx, regs[R_I5]=%lx, regs[R_L1]=%lx, regs[R_L2]=%lx\n",
+                         regs[R_I1], regs[R_I2], regs[R_I5], regs[R_L1], regs[R_L2]);
+    }
+#elif defined(i386) || defined(__i386) || defined(__amd64)
+
+    fp = (uintptr_t) regs[R_FP];
+    if (J->prev_fr.fp == 0) {
+#ifdef X86_COMPILER2
+        /* A workaround for top java frames */
+        J->prev_fr.fp = (uintptr_t)(regs[R_SP] - 2 * POINTER_SIZE);
+#else
+        J->prev_fr.fp = (uintptr_t)(regs[R_SP] - POINTER_SIZE);
+#endif /* COMPILER2 */
+    }
+    if (debug > 2) {
+        printf("Jlookup_by_regs: J->prev_fr.fp = %#lx\n", J->prev_fr.fp);
+    }
+
+    if (read_pointer(J,  fp + OFFSET_interpreter_frame_method, &methodOopPtr) != PS_OK) {
+      methodOopPtr = 0;
+    }
+    if (read_pointer(J,  fp + OFFSET_interpreter_frame_sender_sp, &sender_sp) != PS_OK) {
+      sender_sp = 0;
+    }
+    if (read_pointer(J,  fp + OFFSET_interpreter_frame_bcx_offset, &bcx) != PS_OK) {
+      bcx = 0;
+    }
+#endif /* i386 */
+
+  J->methodOopPtr = methodOopPtr;
+  J->bcx = bcx;
+
+  /* On x86 with C2 JVM: native frame may have wrong regs[R_FP]
+   * For example: JVM_SuspendThread frame poins to the top interpreted frame.
+   * If we call is_methodOop(J, methodOopPtr) before codecache_contains(J, pc)
+   * then we go over and omit both: nmethod and I2CAdapter frames.
+   * Note, that regs[R_PC] is always correct if frame defined correctly.
+   * So it is better to call codecache_contains(J, pc) from the beginning.
+   */
+#ifndef X86_COMPILER2
+  if (is_methodOop(J, J->methodOopPtr)) {
+    result = name_for_imethod(J, bcx, J->methodOopPtr, name, size, jframe);
+    /* If the methodOopPtr is a method then this is highly likely to be
+       an interpreter frame */
+    if (result >= 0) {
+      is_interpreted = 1;
+    }
+  } else
+#endif /* ! X86_COMPILER2 */
+
+  if (codecache_contains(J, pc)) {
+    result = name_for_codecache(J, fp, pc, name, size, jframe, &is_interpreted);
+  }
+#ifdef X86_COMPILER2
+  else if (is_methodOop(J, J->methodOopPtr)) {
+    result = name_for_imethod(J, bcx, J->methodOopPtr, name, size, jframe);
+    /* If the methodOopPtr is a method then this is highly likely to be
+       an interpreter frame */
+    if (result >= 0) {
+      is_interpreted = 1;
+    }
+  }
+#endif /* X86_COMPILER2 */
+  else {
+    if (debug) {
+        fprintf(stderr, "Jlookup_by_regs: END with -1\n\n");
+    }
+    result = -1;
+  }
+  if (!is_interpreted) {
+    sender_sp = 0;
+  }
+  J->curr_fr.sender_sp = sender_sp;
+
+#ifdef X86_COMPILER2
+  if (!J->curr_fr.fp) {
+    J->curr_fr.fp = (jframe->new_fp) ? jframe->new_fp : (uintptr_t)regs[R_FP];
+  }
+  if (!jframe->new_pc && jframe->new_fp) {
+    // This seems dubious
+    read_pointer(J,  jframe->new_fp + POINTER_SIZE,  &jframe->new_pc);
+    CHECK_FAIL(err);
+    if (debug > 2) {
+        printf("Jlookup_by_regs: (update pc) jframe->new_fp: %#llx, jframe->new_pc: %#llx\n",
+               jframe->new_fp, jframe->new_pc);
+    }
+  }
+
+#endif /* X86_COMPILER2 */
+  J->prev_fr = J->curr_fr;
+
+  if (debug)
+      fprintf(stderr, "Jlookup_by_regs: END\n\n");
+
+  return result;
+
+ fail:
+  return err;
+}
+
+void update_gregs(prgregset_t gregs, Jframe_t jframe) {
+#ifdef X86_COMPILER2
+    if (debug > 0) {
+      fprintf(stderr, "update_gregs: before update sp = 0x%llx, fp = 0x%llx, pc = 0x%llx\n", gregs[R_SP], gregs[R_FP], gregs[R_PC]);
+    }
+    /*
+     * A workaround for java C2 frames with unconventional FP.
+     * may have to modify regset with new values for FP/PC/SP when needed.
+     */
+     if (jframe.new_sp) {
+         *((uintptr_t *) &gregs[R_SP]) = (uintptr_t) jframe.new_sp;
+     } else {
+         // *((uintptr_t *) &gregs[R_SP]) = (uintptr_t) gregs[R_FP] + 2 * POINTER_SIZE;
+     }
+
+     if (jframe.new_fp) {
+         *((uintptr_t *) &gregs[R_FP]) = (uintptr_t) jframe.new_fp;
+     }
+     if (jframe.new_pc) {
+         *((uintptr_t *) &gregs[R_PC]) = (uintptr_t) jframe.new_pc;
+     }
+    if (debug > 0) {
+      fprintf(stderr, "update_gregs: after update sp = 0x%llx, fp = 0x%llx, pc = 0x%llx\n", gregs[R_SP], gregs[R_FP], gregs[R_PC]);
+    }
+#endif  /* X86_COMPILER2 */
+}
+
+/*
+ * Iterates over java frames at current location given by 'gregs'.
+ *
+ *  Returns -1 if no java frames are present or if an error is encountered.
+ *  Returns the result of calling 'func' if the return value is non-zero.
+ *  Returns 0 otherwise.
+ */
+int Jframe_iter(jvm_agent_t *J, prgregset_t gregs, java_stack_f *func, void* cld) {
+    char buf[MAX_SYM_SIZE + 1];
+    Jframe_t jframe;
+    int i = 0, res;
+#ifdef X86_COMPILER2
+    if (debug > 0) {
+      fprintf(stderr, "Jframe_iter: Entry sp = 0x%llx, fp = 0x%llx, pc = 0x%llx\n", gregs[R_SP], gregs[R_FP], gregs[R_PC]);
+    }
+#endif  /* X86_COMPILER2 */
+
+    memset(&jframe, 0, sizeof(Jframe_t));
+    memset(buf, 0, sizeof(buf));
+    res =  Jlookup_by_regs(J, gregs, buf, sizeof(buf), &jframe);
+    if (res != PS_OK)
+        return (-1);
+
+
+    res = func(cld, gregs, buf, (jframe.locinf)? jframe.bci : -1,
+               jframe.line, NULL);
+    if (res != 0) {
+        update_gregs(gregs, jframe);
+        return (res);
+    }
+    for (i = 1; i < jframe.vf_cnt; i++) {
+        Jget_vframe(J, i, buf, sizeof(buf), &jframe);
+        res = func(cld, gregs, buf, (jframe.locinf)? jframe.bci : -1,
+                   jframe.line, NULL);
+        if (res != 0) {
+            update_gregs(gregs, jframe);
+            return (res);
+        }
+    }
+    update_gregs(gregs, jframe);
+    return (0);
+}