1 /*
   2  * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "logging/log.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "prims/jvm.h"
  29 #include "runtime/arguments.hpp"
  30 #include "runtime/java.hpp"
  31 #include "runtime/mutex.hpp"
  32 #include "runtime/mutexLocker.hpp"
  33 #include "runtime/orderAccess.inline.hpp"
  34 #include "runtime/os.hpp"
  35 #include "runtime/perfData.hpp"
  36 #include "runtime/perfMemory.hpp"
  37 #include "runtime/safepoint.hpp"
  38 #include "runtime/statSampler.hpp"
  39 #include "utilities/globalDefinitions.hpp"
  40 
  41 // Prefix of performance data file.
  42 const char               PERFDATA_NAME[] = "hsperfdata";
  43 
  44 // Add 1 for the '_' character between PERFDATA_NAME and pid. The '\0' terminating
  45 // character will be included in the sizeof(PERFDATA_NAME) operation.
  46 static const size_t PERFDATA_FILENAME_LEN = sizeof(PERFDATA_NAME) +
  47                                             UINT_CHARS + 1;
  48 
  49 char*                    PerfMemory::_start = NULL;
  50 char*                    PerfMemory::_end = NULL;
  51 char*                    PerfMemory::_top = NULL;
  52 size_t                   PerfMemory::_capacity = 0;
  53 jint                     PerfMemory::_initialized = false;
  54 PerfDataPrologue*        PerfMemory::_prologue = NULL;
  55 
  56 void perfMemory_init() {
  57 
  58   if (!UsePerfData) return;
  59 
  60   PerfMemory::initialize();
  61 }
  62 
  63 void perfMemory_exit() {
  64 
  65   if (!UsePerfData) return;
  66   if (!PerfMemory::is_initialized()) return;
  67 
  68   // Only destroy PerfData objects if we're at a safepoint and the
  69   // StatSampler is not active. Otherwise, we risk removing PerfData
  70   // objects that are currently being used by running JavaThreads
  71   // or the StatSampler. This method is invoked while we are not at
  72   // a safepoint during a VM abort so leaving the PerfData objects
  73   // around may also help diagnose the failure. In rare cases,
  74   // PerfData objects are used in parallel with a safepoint. See
  75   // the work around in PerfDataManager::destroy().
  76   //
  77   if (SafepointSynchronize::is_at_safepoint() && !StatSampler::is_active()) {
  78     PerfDataManager::destroy();
  79   }
  80 
  81   // Remove the persistent external resources, if any. This method
  82   // does not unmap or invalidate any virtual memory allocated during
  83   // initialization.
  84   //
  85   PerfMemory::destroy();
  86 }
  87 
  88 void PerfMemory::initialize() {
  89 
  90   if (_prologue != NULL)
  91     // initialization already performed
  92     return;
  93 
  94   size_t capacity = align_up(PerfDataMemorySize,
  95                                   os::vm_allocation_granularity());
  96 
  97   log_debug(perf, memops)("PerfDataMemorySize = " SIZE_FORMAT ","
  98                           " os::vm_allocation_granularity = %d,"
  99                           " adjusted size = " SIZE_FORMAT "\n",
 100                           PerfDataMemorySize,
 101                           os::vm_allocation_granularity(),
 102                           capacity);
 103 
 104   // allocate PerfData memory region
 105   create_memory_region(capacity);
 106 
 107   if (_start == NULL) {
 108 
 109     // the PerfMemory region could not be created as desired. Rather
 110     // than terminating the JVM, we revert to creating the instrumentation
 111     // on the C heap. When running in this mode, external monitoring
 112     // clients cannot attach to and monitor this JVM.
 113     //
 114     // the warning is issued only in debug mode in order to avoid
 115     // additional output to the stdout or stderr output streams.
 116     //
 117     if (PrintMiscellaneous && Verbose) {
 118       warning("Could not create PerfData Memory region, reverting to malloc");
 119     }
 120 
 121     _prologue = NEW_C_HEAP_OBJ(PerfDataPrologue, mtInternal);
 122   }
 123   else {
 124 
 125     // the PerfMemory region was created as expected.
 126 
 127     log_debug(perf, memops)("PerfMemory created: address = " INTPTR_FORMAT ","
 128                             " size = " SIZE_FORMAT "\n",
 129                             p2i(_start),
 130                             _capacity);
 131 
 132     _prologue = (PerfDataPrologue *)_start;
 133     _end = _start + _capacity;
 134     _top = _start + sizeof(PerfDataPrologue);
 135   }
 136 
 137   assert(_prologue != NULL, "prologue pointer must be initialized");
 138 
 139 #ifdef VM_LITTLE_ENDIAN
 140   _prologue->magic = (jint)0xc0c0feca;
 141   _prologue->byte_order = PERFDATA_LITTLE_ENDIAN;
 142 #else
 143   _prologue->magic = (jint)0xcafec0c0;
 144   _prologue->byte_order = PERFDATA_BIG_ENDIAN;
 145 #endif
 146 
 147   _prologue->major_version = PERFDATA_MAJOR_VERSION;
 148   _prologue->minor_version = PERFDATA_MINOR_VERSION;
 149   _prologue->accessible = 0;
 150 
 151   _prologue->entry_offset = sizeof(PerfDataPrologue);
 152   _prologue->num_entries = 0;
 153   _prologue->used = 0;
 154   _prologue->overflow = 0;
 155   _prologue->mod_time_stamp = 0;
 156 
 157   OrderAccess::release_store(&_initialized, 1);
 158 }
 159 
 160 void PerfMemory::destroy() {
 161 
 162   if (_prologue == NULL) return;
 163 
 164   if (_start != NULL && _prologue->overflow != 0) {
 165 
 166     // This state indicates that the contiguous memory region exists and
 167     // that it wasn't large enough to hold all the counters. In this case,
 168     // we output a warning message to the user on exit if the -XX:+Verbose
 169     // flag is set (a debug only flag). External monitoring tools can detect
 170     // this condition by monitoring the _prologue->overflow word.
 171     //
 172     // There are two tunables that can help resolve this issue:
 173     //   - increase the size of the PerfMemory with -XX:PerfDataMemorySize=<n>
 174     //   - decrease the maximum string constant length with
 175     //     -XX:PerfMaxStringConstLength=<n>
 176     //
 177     if (PrintMiscellaneous && Verbose) {
 178       warning("PerfMemory Overflow Occurred.\n"
 179               "\tCapacity = " SIZE_FORMAT " bytes"
 180               "  Used = " SIZE_FORMAT " bytes"
 181               "  Overflow = " INT32_FORMAT " bytes"
 182               "\n\tUse -XX:PerfDataMemorySize=<size> to specify larger size.",
 183               PerfMemory::capacity(),
 184               PerfMemory::used(),
 185               _prologue->overflow);
 186     }
 187   }
 188 
 189   if (_start != NULL) {
 190 
 191     // this state indicates that the contiguous memory region was successfully
 192     // and that persistent resources may need to be cleaned up. This is
 193     // expected to be the typical condition.
 194     //
 195     delete_memory_region();
 196   }
 197 
 198   _start = NULL;
 199   _end = NULL;
 200   _top = NULL;
 201   _prologue = NULL;
 202   _capacity = 0;
 203 }
 204 
 205 // allocate an aligned block of memory from the PerfData memory
 206 // region. This method assumes that the PerfData memory region
 207 // was aligned on a double word boundary when created.
 208 //
 209 char* PerfMemory::alloc(size_t size) {
 210 
 211   if (!UsePerfData) return NULL;
 212 
 213   MutexLocker ml(PerfDataMemAlloc_lock);
 214 
 215   assert(_prologue != NULL, "called before initialization");
 216 
 217   // check that there is enough memory for this request
 218   if ((_top + size) >= _end) {
 219 
 220     _prologue->overflow += (jint)size;
 221 
 222     return NULL;
 223   }
 224 
 225   char* result = _top;
 226 
 227   _top += size;
 228 
 229   assert(contains(result), "PerfData memory pointer out of range");
 230 
 231   _prologue->used = (jint)used();
 232   _prologue->num_entries = _prologue->num_entries + 1;
 233 
 234   return result;
 235 }
 236 
 237 void PerfMemory::mark_updated() {
 238   if (!UsePerfData) return;
 239 
 240   _prologue->mod_time_stamp = os::elapsed_counter();
 241 }
 242 
 243 // Returns the complete path including the file name of performance data file.
 244 // Caller is expected to release the allocated memory.
 245 char* PerfMemory::get_perfdata_file_path() {
 246   char* dest_file = NULL;
 247 
 248   if (PerfDataSaveFile != NULL) {
 249     // dest_file_name stores the validated file name if file_name
 250     // contains %p which will be replaced by pid.
 251     dest_file = NEW_C_HEAP_ARRAY(char, JVM_MAXPATHLEN, mtInternal);
 252     if(!Arguments::copy_expand_pid(PerfDataSaveFile, strlen(PerfDataSaveFile),
 253                                    dest_file, JVM_MAXPATHLEN)) {
 254       FREE_C_HEAP_ARRAY(char, dest_file);
 255       if (PrintMiscellaneous && Verbose) {
 256         warning("Invalid performance data file path name specified, "\
 257                 "fall back to a default name");
 258       }
 259     } else {
 260       return dest_file;
 261     }
 262   }
 263   // create the name of the file for retaining the instrumentation memory.
 264   dest_file = NEW_C_HEAP_ARRAY(char, PERFDATA_FILENAME_LEN, mtInternal);
 265   jio_snprintf(dest_file, PERFDATA_FILENAME_LEN,
 266                "%s_%d", PERFDATA_NAME, os::current_process_id());
 267 
 268   return dest_file;
 269 }