Revert 126020 - Experiment for updating the tcmalloc chromium branch to r144 (gperftools 2.0).

third_party/tcmalloc/chromium/src/base/vdso_support.h

Index: third_party/tcmalloc/chromium/src/base/vdso_support.h
===================================================================
--- third_party/tcmalloc/chromium/src/base/vdso_support.h	(revision 126022)
+++ third_party/tcmalloc/chromium/src/base/vdso_support.h	(working copy)
@@ -1,35 +1,6 @@
-// Copyright (c) 2008, Google Inc.
-// All rights reserved.
+// Copyright 2008 Google Inc. All Rights Reserved.
+// Author: ppluzhnikov@google.com (Paul Pluzhnikov)
 //
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// ---
-// Author: Paul Pluzhnikov
-//
 // Allow dynamic symbol lookup in the kernel VDSO page.
 //
 // VDSO stands for "Virtual Dynamic Shared Object" -- a page of
@@ -56,14 +27,19 @@
 #define BASE_VDSO_SUPPORT_H_
 
 #include <config.h>
+#ifdef HAVE_FEATURES_H
+#include <features.h>   // for __GLIBC__
+#endif
 #include "base/basictypes.h"
-#include "base/elf_mem_image.h"
 
-#ifdef HAVE_ELF_MEM_IMAGE
+// Maybe one day we can rewrite this file not to require the elf
+// symbol extensions in glibc, but for right now we need them.
+#if defined(__ELF__) && defined(__GLIBC__)
 
 #define HAVE_VDSO_SUPPORT 1
 
 #include <stdlib.h>     // for NULL
+#include <link.h>  // for ElfW
 
 namespace base {
 
@@ -71,17 +47,45 @@
 // use any memory allocation routines.
 class VDSOSupport {
  public:
+  // Sentinel: there could never be a VDSO at this address.
+  static const void *const kInvalidBase;
+
+  // Information about a single vdso symbol.
+  // All pointers are into .dynsym, .dynstr, or .text of the VDSO.
+  // Do not free() them or modify through them.
+  struct SymbolInfo {
+    const char      *name;      // E.g. "__vdso_getcpu"
+    const char      *version;   // E.g. "LINUX_2.6", could be ""
+                                // for unversioned symbol.
+    const void      *address;   // Relocated symbol address.
+    const ElfW(Sym) *symbol;    // Symbol in the dynamic symbol table.
+  };
+
+  // Supports iteration over all dynamic symbols.
+  class SymbolIterator {
+   public:
+    friend class VDSOSupport;
+    const SymbolInfo *operator->() const;
+    const SymbolInfo &operator*() const;
+    SymbolIterator& operator++();
+    bool operator!=(const SymbolIterator &rhs) const;
+    bool operator==(const SymbolIterator &rhs) const;
+   private:
+    SymbolIterator(const void *const image, int index);
+    void Update(int incr);
+    SymbolInfo info_;
+    int index_;
+    const void *const image_;
+  };
+
   VDSOSupport();
 
-  typedef ElfMemImage::SymbolInfo SymbolInfo;
-  typedef ElfMemImage::SymbolIterator SymbolIterator;
-
   // Answers whether we have a vdso at all.
   bool IsPresent() const { return image_.IsPresent(); }
 
   // Allow to iterate over all VDSO symbols.
-  SymbolIterator begin() const { return image_.begin(); }
-  SymbolIterator end() const { return image_.end(); }
+  SymbolIterator begin() const;
+  SymbolIterator end() const;
 
   // Look up versioned dynamic symbol in the kernel VDSO.
   // Returns false if VDSO is not present, or doesn't contain given
@@ -107,6 +111,33 @@
   static const void *Init();
 
  private:
+  // An in-memory ELF image (may not exist on disk).
+  class ElfMemImage {
+   public:
+    explicit ElfMemImage(const void *base);
+    void                 Init(const void *base);
+    bool                 IsPresent() const { return ehdr_ != NULL; }
+    const ElfW(Phdr)*    GetPhdr(int index) const;
+    const ElfW(Sym)*     GetDynsym(int index) const;
+    const ElfW(Versym)*  GetVersym(int index) const;
+    const ElfW(Verdef)*  GetVerdef(int index) const;
+    const ElfW(Verdaux)* GetVerdefAux(const ElfW(Verdef) *verdef) const;
+    const char*          GetDynstr(ElfW(Word) offset) const;
+    const void*          GetSymAddr(const ElfW(Sym) *sym) const;
+    const char*          GetVerstr(ElfW(Word) offset) const;
+    int                  GetNumSymbols() const;
+   private:
+    const ElfW(Ehdr) *ehdr_;
+    const ElfW(Sym) *dynsym_;
+    const ElfW(Versym) *versym_;
+    const ElfW(Verdef) *verdef_;
+    const ElfW(Word) *hash_;
+    const char *dynstr_;
+    size_t strsize_;
+    size_t verdefnum_;
+    ElfW(Addr) link_base_;     // Link-time base (p_vaddr of first PT_LOAD).
+  };
+
   // image_ represents VDSO ELF image in memory.
   // image_.ehdr_ == NULL implies there is no VDSO.
   ElfMemImage image_;
@@ -150,6 +181,6 @@
 int GetCPU();
 }  // namespace base
 
-#endif  // HAVE_ELF_MEM_IMAGE
+#endif  // __ELF__ and __GLIBC__
 
 #endif  // BASE_VDSO_SUPPORT_H_