--- a/src/hotspot/share/utilities/elfFile.cpp	Wed Feb 14 16:42:00 2018 +0100
+++ b/src/hotspot/share/utilities/elfFile.cpp	Wed Feb 14 17:20:59 2018 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. 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
@@ -31,60 +31,150 @@
 #include <limits.h>
 #include <new>
 
+#include "logging/log.hpp"
 #include "memory/allocation.inline.hpp"
+#include "memory/resourceArea.hpp"
 #include "utilities/decoder.hpp"
 #include "utilities/elfFile.hpp"
 #include "utilities/elfFuncDescTable.hpp"
 #include "utilities/elfStringTable.hpp"
 #include "utilities/elfSymbolTable.hpp"
+#include "utilities/ostream.hpp"
 
+// For test only, disable elf section cache and force to read from file directly.
+bool ElfFile::_do_not_cache_elf_section = false;
+
+ElfSection::ElfSection(FILE* fd, const Elf_Shdr& hdr) : _section_data(NULL) {
+  _stat = load_section(fd, hdr);
+}
+
+ElfSection::~ElfSection() {
+  if (_section_data != NULL) {
+    os::free(_section_data);
+  }
+}
+
+NullDecoder::decoder_status ElfSection::load_section(FILE* const fd, const Elf_Shdr& shdr) {
+  memcpy((void*)&_section_hdr, (const void*)&shdr, sizeof(shdr));
+
+  if (ElfFile::_do_not_cache_elf_section) {
+    log_debug(decoder)("Elf section cache is disabled");
+    return NullDecoder::no_error;
+  }
+
+  _section_data = os::malloc(shdr.sh_size, mtInternal);
+  // No enough memory for caching. It is okay, we can try to read from
+  // file instead.
+  if (_section_data == NULL) return NullDecoder::no_error;
 
-ElfFile::ElfFile(const char* filepath) {
-  assert(filepath, "null file path");
-  memset(&m_elfHdr, 0, sizeof(m_elfHdr));
-  m_string_tables = NULL;
-  m_symbol_tables = NULL;
-  m_funcDesc_table = NULL;
-  m_next = NULL;
-  m_status = NullDecoder::no_error;
+  MarkedFileReader mfd(fd);
+  if (mfd.has_mark() &&
+      mfd.set_position(shdr.sh_offset) &&
+      mfd.read(_section_data, shdr.sh_size)) {
+    return NullDecoder::no_error;
+  } else {
+    os::free(_section_data);
+    _section_data = NULL;
+    return NullDecoder::file_invalid;
+  }
+}
+
+bool FileReader::read(void* buf, size_t size) {
+  assert(buf != NULL, "no buffer");
+  assert(size > 0, "no space");
+  return fread(buf, size, 1, _fd) == 1;
+}
+
+int FileReader::read_buffer(void* buf, size_t size) {
+  assert(buf != NULL, "no buffer");
+  assert(size > 0, "no space");
+  return fread(buf, 1, size, _fd);
+}
+
+bool FileReader::set_position(long offset) {
+  return fseek(_fd, offset, SEEK_SET) == 0;
+}
+
+MarkedFileReader::MarkedFileReader(FILE* fd) : FileReader(fd) {
+  _marked_pos = ftell(fd);
+}
+
+MarkedFileReader::~MarkedFileReader() {
+  if (_marked_pos != -1) {
+    set_position(_marked_pos);
+  }
+}
+
+ElfFile::ElfFile(const char* filepath) :
+  _string_tables(NULL), _symbol_tables(NULL), _funcDesc_table(NULL),
+  _next(NULL), _status(NullDecoder::no_error),
+  _shdr_string_table(NULL),  _file(NULL), _filepath(NULL) {
+  memset(&_elfHdr, 0, sizeof(_elfHdr));
 
   int len = strlen(filepath) + 1;
-  m_filepath = (const char*)os::malloc(len * sizeof(char), mtInternal);
-  if (m_filepath != NULL) {
-    strcpy((char*)m_filepath, filepath);
-    m_file = fopen(filepath, "r");
-    if (m_file != NULL) {
-      load_tables();
-    } else {
-      m_status = NullDecoder::file_not_found;
-    }
-  } else {
-    m_status = NullDecoder::out_of_memory;
+  _filepath = (char*)os::malloc(len * sizeof(char), mtInternal);
+  if (_filepath == NULL) {
+    _status = NullDecoder::out_of_memory;
+    return;
+  }
+  strcpy(_filepath, filepath);
+
+  _status = parse_elf(filepath);
+
+  // we no longer need section header string table
+  if (_shdr_string_table != NULL) {
+    delete _shdr_string_table;
+    _shdr_string_table = NULL;
   }
 }
 
 ElfFile::~ElfFile() {
-  if (m_string_tables != NULL) {
-    delete m_string_tables;
+  if (_shdr_string_table != NULL) {
+    delete _shdr_string_table;
   }
 
-  if (m_symbol_tables != NULL) {
-    delete m_symbol_tables;
+  cleanup_tables();
+
+  if (_file != NULL) {
+    fclose(_file);
+  }
+
+  if (_filepath != NULL) {
+    os::free((void*)_filepath);
   }
 
-  if (m_file != NULL) {
-    fclose(m_file);
+  if (_next != NULL) {
+    delete _next;
+  }
+}
+
+void ElfFile::cleanup_tables() {
+  if (_string_tables != NULL) {
+    delete _string_tables;
+    _string_tables = NULL;
+  }
+
+  if (_symbol_tables != NULL) {
+    delete _symbol_tables;
+    _symbol_tables = NULL;
   }
 
-  if (m_filepath != NULL) {
-    os::free((void*)m_filepath);
+  if (_funcDesc_table != NULL) {
+    delete _funcDesc_table;
+    _funcDesc_table = NULL;
   }
+}
 
-  if (m_next != NULL) {
-    delete m_next;
+NullDecoder::decoder_status ElfFile::parse_elf(const char* filepath) {
+  assert(filepath, "null file path");
+
+  _file = fopen(filepath, "r");
+  if (_file != NULL) {
+    return load_tables();
+  } else {
+    return NullDecoder::file_not_found;
   }
-};
-
+}
 
 //Check elf header to ensure the file is valid.
 bool ElfFile::is_elf_file(Elf_Ehdr& hdr) {
@@ -96,116 +186,134 @@
       ELFDATANONE != hdr.e_ident[EI_DATA]);
 }
 
-bool ElfFile::load_tables() {
-  assert(m_file, "file not open");
-  assert(!NullDecoder::is_error(m_status), "already in error");
+NullDecoder::decoder_status ElfFile::load_tables() {
+  assert(_file, "file not open");
+  assert(!NullDecoder::is_error(_status), "already in error");
 
+  FileReader freader(fd());
   // read elf file header
-  if (fread(&m_elfHdr, sizeof(m_elfHdr), 1, m_file) != 1) {
-    m_status = NullDecoder::file_invalid;
-    return false;
+  if (!freader.read(&_elfHdr, sizeof(_elfHdr))) {
+    return NullDecoder::file_invalid;
   }
 
-  if (!is_elf_file(m_elfHdr)) {
-    m_status = NullDecoder::file_invalid;
-    return false;
+  // Check signature
+  if (!is_elf_file(_elfHdr)) {
+    return NullDecoder::file_invalid;
   }
 
   // walk elf file's section headers, and load string tables
   Elf_Shdr shdr;
-  if (!fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {
-    if (NullDecoder::is_error(m_status)) return false;
+  if (!freader.set_position(_elfHdr.e_shoff)) {
+    return NullDecoder::file_invalid;
+  }
 
-    for (int index = 0; index < m_elfHdr.e_shnum; index ++) {
-      if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {
-        m_status = NullDecoder::file_invalid;
-        return false;
-      }
-      if (shdr.sh_type == SHT_STRTAB) {
-        // string tables
-        ElfStringTable* table = new (std::nothrow) ElfStringTable(m_file, shdr, index);
-        if (table == NULL) {
-          m_status = NullDecoder::out_of_memory;
-          return false;
-        }
-        add_string_table(table);
-      } else if (shdr.sh_type == SHT_SYMTAB || shdr.sh_type == SHT_DYNSYM) {
-        // symbol tables
-        ElfSymbolTable* table = new (std::nothrow) ElfSymbolTable(m_file, shdr);
-        if (table == NULL) {
-          m_status = NullDecoder::out_of_memory;
-          return false;
-        }
-        add_symbol_table(table);
-      }
+  for (int index = 0; index < _elfHdr.e_shnum; index ++) {
+    if (!freader.read(&shdr, sizeof(shdr))) {
+      return NullDecoder::file_invalid;
     }
 
-#if defined(PPC64) && !defined(ABI_ELFv2)
-    // Now read the .opd section wich contains the PPC64 function descriptor table.
-    // The .opd section is only available on PPC64 (see for example:
-    // http://refspecs.linuxfoundation.org/LSB_3.1.1/LSB-Core-PPC64/LSB-Core-PPC64/specialsections.html)
-    // so this code should do no harm on other platforms but because of performance reasons we only
-    // execute it on PPC64 platforms.
-    // Notice that we can only find the .opd section after we have successfully read in the string
-    // tables in the previous loop, because we need to query the name of each section which is
-    // contained in one of the string tables (i.e. the one with the index m_elfHdr.e_shstrndx).
-
-    // Reset the file pointer
-    if (fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {
-      m_status = NullDecoder::file_invalid;
-      return false;
+    if (shdr.sh_type == SHT_STRTAB) {
+      // string tables
+      ElfStringTable* table = new (std::nothrow) ElfStringTable(fd(), shdr, index);
+      if (table == NULL) {
+        return NullDecoder::out_of_memory;
+      }
+      if (index == _elfHdr.e_shstrndx) {
+        assert(_shdr_string_table == NULL, "Only set once");
+        _shdr_string_table = table;
+      } else {
+        add_string_table(table);
+      }
+    } else if (shdr.sh_type == SHT_SYMTAB || shdr.sh_type == SHT_DYNSYM) {
+      // symbol tables
+      ElfSymbolTable* table = new (std::nothrow) ElfSymbolTable(fd(), shdr);
+      if (table == NULL) {
+        return NullDecoder::out_of_memory;
+      }
+      add_symbol_table(table);
     }
-    for (int index = 0; index < m_elfHdr.e_shnum; index ++) {
-      if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {
-        m_status = NullDecoder::file_invalid;
-        return false;
-      }
-      if (m_elfHdr.e_shstrndx != SHN_UNDEF && shdr.sh_type == SHT_PROGBITS) {
-        ElfStringTable* string_table = get_string_table(m_elfHdr.e_shstrndx);
-        if (string_table == NULL) {
-          m_status = NullDecoder::file_invalid;
-          return false;
-        }
-        char buf[8]; // '8' is enough because we only want to read ".opd"
-        if (string_table->string_at(shdr.sh_name, buf, sizeof(buf)) && !strncmp(".opd", buf, 4)) {
-          m_funcDesc_table = new (std::nothrow) ElfFuncDescTable(m_file, shdr, index);
-          if (m_funcDesc_table == NULL) {
-            m_status = NullDecoder::out_of_memory;
-            return false;
-          }
-          break;
-        }
+  }
+#if defined(PPC64) && !defined(ABI_ELFv2)
+  // Now read the .opd section wich contains the PPC64 function descriptor table.
+  // The .opd section is only available on PPC64 (see for example:
+  // http://refspecs.linuxfoundation.org/LSB_3.1.1/LSB-Core-PPC64/LSB-Core-PPC64/specialsections.html)
+  // so this code should do no harm on other platforms but because of performance reasons we only
+  // execute it on PPC64 platforms.
+  // Notice that we can only find the .opd section after we have successfully read in the string
+  // tables in the previous loop, because we need to query the name of each section which is
+  // contained in one of the string tables (i.e. the one with the index m_elfHdr.e_shstrndx).
+
+  // Reset the file pointer
+  int sect_index = section_by_name(".opd", shdr);
+
+  if (sect_index == -1) {
+    return NullDecoder::file_invalid;
+  }
+
+  _funcDesc_table = new (std::nothrow) ElfFuncDescTable(_file, shdr, sect_index);
+  if (_funcDesc_table == NULL) {
+      return NullDecoder::out_of_memory;
+  }
+#endif
+  return NullDecoder::no_error;
+}
+
+int ElfFile::section_by_name(const char* name, Elf_Shdr& hdr) {
+  assert(name != NULL, "No section name");
+  size_t len = strlen(name) + 1;
+  ResourceMark rm;
+  char* buf = NEW_RESOURCE_ARRAY(char, len);
+  if (buf == NULL) {
+    return -1;
+  }
+
+  assert(_shdr_string_table != NULL, "Section header string table should be loaded");
+  ElfStringTable* const table = _shdr_string_table;
+  MarkedFileReader mfd(fd());
+  if (!mfd.has_mark() || !mfd.set_position(_elfHdr.e_shoff)) return -1;
+
+  int sect_index = -1;
+  for (int index = 0; index < _elfHdr.e_shnum; index ++) {
+    if (!mfd.read((void*)&hdr, sizeof(hdr))) {
+      break;
+    }
+    if (table->string_at(hdr.sh_name, buf, len)) {
+      if (strncmp(buf, name, len) == 0) {
+        sect_index = index;
+        break;
       }
     }
-#endif
-
   }
-  return true;
+  return sect_index;
 }
 
 bool ElfFile::decode(address addr, char* buf, int buflen, int* offset) {
   // something already went wrong, just give up
-  if (NullDecoder::is_error(m_status)) {
+  if (NullDecoder::is_error(_status)) {
     return false;
   }
-  ElfSymbolTable* symbol_table = m_symbol_tables;
+
   int string_table_index;
   int pos_in_string_table;
   int off = INT_MAX;
   bool found_symbol = false;
+  ElfSymbolTable* symbol_table = _symbol_tables;
+
   while (symbol_table != NULL) {
-    if (symbol_table->lookup(addr, &string_table_index, &pos_in_string_table, &off, m_funcDesc_table)) {
+    if (symbol_table->lookup(addr, &string_table_index, &pos_in_string_table, &off, _funcDesc_table)) {
       found_symbol = true;
       break;
     }
-    symbol_table = symbol_table->m_next;
+    symbol_table = symbol_table->next();
   }
-  if (!found_symbol) return false;
+  if (!found_symbol) {
+    return false;
+  }
 
   ElfStringTable* string_table = get_string_table(string_table_index);
 
   if (string_table == NULL) {
-    m_status = NullDecoder::file_invalid;
+    _status = NullDecoder::file_invalid;
     return false;
   }
   if (offset) *offset = off;
@@ -213,74 +321,31 @@
   return string_table->string_at(pos_in_string_table, buf, buflen);
 }
 
-
 void ElfFile::add_symbol_table(ElfSymbolTable* table) {
-  if (m_symbol_tables == NULL) {
-    m_symbol_tables = table;
+  if (_symbol_tables == NULL) {
+    _symbol_tables = table;
   } else {
-    table->m_next = m_symbol_tables;
-    m_symbol_tables = table;
+    table->set_next(_symbol_tables);
+    _symbol_tables = table;
   }
 }
 
 void ElfFile::add_string_table(ElfStringTable* table) {
-  if (m_string_tables == NULL) {
-    m_string_tables = table;
+  if (_string_tables == NULL) {
+    _string_tables = table;
   } else {
-    table->m_next = m_string_tables;
-    m_string_tables = table;
+    table->set_next(_string_tables);
+    _string_tables = table;
   }
 }
 
 ElfStringTable* ElfFile::get_string_table(int index) {
-  ElfStringTable* p = m_string_tables;
+  ElfStringTable* p = _string_tables;
   while (p != NULL) {
     if (p->index() == index) return p;
-    p = p->m_next;
+    p = p->next();
   }
   return NULL;
 }
 
-#ifdef LINUX
-bool ElfFile::specifies_noexecstack(const char* filepath) {
-  // Returns true if the elf file is marked NOT to require an executable stack,
-  // or if the file could not be opened.
-  // Returns false if the elf file requires an executable stack, the stack flag
-  // is not set at all, or if the file can not be read.
-  if (filepath == NULL) return true;
-
-  FILE* file = fopen(filepath, "r");
-  if (file == NULL)  return true;
-
-  // AARCH64 defaults to noexecstack. All others default to execstack.
-#ifdef AARCH64
-  bool result = true;
-#else
-  bool result = false;
-#endif
-
-  // Read file header
-  Elf_Ehdr head;
-  if (fread(&head, sizeof(Elf_Ehdr), 1, file) == 1 &&
-      is_elf_file(head) &&
-      fseek(file, head.e_phoff, SEEK_SET) == 0) {
-
-    // Read program header table
-    Elf_Phdr phdr;
-    for (int index = 0; index < head.e_phnum; index ++) {
-      if (fread((void*)&phdr, sizeof(Elf_Phdr), 1, file) != 1) {
-        result = false;
-        break;
-      }
-      if (phdr.p_type == PT_GNU_STACK) {
-        result = (phdr.p_flags == (PF_R | PF_W));
-        break;
-      }
-    }
-  }
-  fclose(file);
-  return result;
-}
-#endif // LINUX
-
 #endif // !_WINDOWS && !__APPLE__