Update the tcmalloc chromium branch to r144 (gperftools 2.0), and merge chromium-specific changes.

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

 // Copyright (c) 2008, Google Inc.
 // All rights reserved.
 // 
 // 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
@@ skipping 25 matching lines @@
 //
 
 #include "base/vdso_support.h"
 
 #ifdef HAVE_VDSO_SUPPORT     // defined in vdso_support.h
 
 #include <fcntl.h>
 #include <stddef.h>   // for std::ptrdiff_t
 
 #include "base/atomicops.h"  // for MemoryBarrier
+#include "base/linux_syscall_support.h"
 #include "base/logging.h"
-#include "base/linux_syscall_support.h"
 #include "base/dynamic_annotations.h"
 #include "base/basictypes.h"  // for COMPILE_ASSERT
 
 using base::subtle::MemoryBarrier;
 
 #ifndef AT_SYSINFO_EHDR
 #define AT_SYSINFO_EHDR 33
 #endif
 
-// From binutils/include/elf/common.h (this doesn't appear to be documented
-// anywhere else).
-//
-//   /* This flag appears in a Versym structure.  It means that the symbol
-//      is hidden, and is only visible with an explicit version number.
-//      This is a GNU extension.  */
-//   #define VERSYM_HIDDEN           0x8000
-//
-//   /* This is the mask for the rest of the Versym information.  */
-//   #define VERSYM_VERSION          0x7fff
-
-#define VERSYM_VERSION 0x7fff
-
 namespace base {
 
-namespace {
-template <int N> class ElfClass {
- public:
-  static const int kElfClass = -1;
-  static int ElfBind(const ElfW(Sym) *) {
-    CHECK(false); // << "Unexpected word size";
-    return 0;
-  }
-  static int ElfType(const ElfW(Sym) *) {
-    CHECK(false); // << "Unexpected word size";
-    return 0;
-  }
-};
-
-template <> class ElfClass<32> {
- public:
-  static const int kElfClass = ELFCLASS32;
-  static int ElfBind(const ElfW(Sym) *symbol) {
-    return ELF32_ST_BIND(symbol->st_info);
-  }
-  static int ElfType(const ElfW(Sym) *symbol) {
-    return ELF32_ST_TYPE(symbol->st_info);
-  }
-};
-
-template <> class ElfClass<64> {
- public:
-  static const int kElfClass = ELFCLASS64;
-  static int ElfBind(const ElfW(Sym) *symbol) {
-    return ELF64_ST_BIND(symbol->st_info);
-  }
-  static int ElfType(const ElfW(Sym) *symbol) {
-    return ELF64_ST_TYPE(symbol->st_info);
-  }
-};
-
-typedef ElfClass<__WORDSIZE> CurrentElfClass;
-
-// Extract an element from one of the ELF tables, cast it to desired type.
-// This is just a simple arithmetic and a glorified cast.
-// Callers are responsible for bounds checking.
-template <class T>
-const T* GetTableElement(const ElfW(Ehdr) *ehdr,
-                         ElfW(Off) table_offset,
-                         ElfW(Word) element_size,
-                         size_t index) {
-  return reinterpret_cast<const T*>(reinterpret_cast<const char *>(ehdr)
-                                    + table_offset
-                                    + index * element_size);
-}
-}  // namespace
-
-const void *const VDSOSupport::kInvalidBase =
-    reinterpret_cast<const void *>(~0L);
-
-const void *VDSOSupport::vdso_base_ = kInvalidBase;
+const void *VDSOSupport::vdso_base_ = ElfMemImage::kInvalidBase;
 VDSOSupport::GetCpuFn VDSOSupport::getcpu_fn_ = &InitAndGetCPU;
-
-VDSOSupport::ElfMemImage::ElfMemImage(const void *base) {
-  CHECK(base != kInvalidBase);
-  Init(base);
-}
-
-int VDSOSupport::ElfMemImage::GetNumSymbols() const {
-  if (!hash_) {
-    return 0;
-  }
-  // See http://www.caldera.com/developers/gabi/latest/ch5.dynamic.html#hash
-  return hash_[1];
-}
-
-const ElfW(Sym) *VDSOSupport::ElfMemImage::GetDynsym(int index) const {
-  CHECK_LT(index, GetNumSymbols());
-  return dynsym_ + index;
-}
-
-const ElfW(Versym) *VDSOSupport::ElfMemImage::GetVersym(int index) const {
-  CHECK_LT(index, GetNumSymbols());
-  return versym_ + index;
-}
-
-const ElfW(Phdr) *VDSOSupport::ElfMemImage::GetPhdr(int index) const {
-  CHECK_LT(index, ehdr_->e_phnum);
-  return GetTableElement<ElfW(Phdr)>(ehdr_,
-                                     ehdr_->e_phoff,
-                                     ehdr_->e_phentsize,
-                                     index);
-}
-
-const char *VDSOSupport::ElfMemImage::GetDynstr(ElfW(Word) offset) const {
-  CHECK_LT(offset, strsize_);
-  return dynstr_ + offset;
-}
-
-const void *VDSOSupport::ElfMemImage::GetSymAddr(const ElfW(Sym) *sym) const {
-  if (sym->st_shndx == SHN_UNDEF || sym->st_shndx >= SHN_LORESERVE) {
-    // Symbol corresponds to "special" (e.g. SHN_ABS) section.
-    return reinterpret_cast<const void *>(sym->st_value);
-  }
-  CHECK_LT(link_base_, sym->st_value);
-  return GetTableElement<char>(ehdr_, 0, 1, sym->st_value) - link_base_;
-}
-
-const ElfW(Verdef) *VDSOSupport::ElfMemImage::GetVerdef(int index) const {
-  CHECK_LE(index, verdefnum_);
-  const ElfW(Verdef) *version_definition = verdef_;
-  while (version_definition->vd_ndx < index && version_definition->vd_next) {
-    const char *const version_definition_as_char =
-        reinterpret_cast<const char *>(version_definition);
-    version_definition =
-        reinterpret_cast<const ElfW(Verdef) *>(version_definition_as_char +
-                                               version_definition->vd_next);
-  }
-  return version_definition->vd_ndx == index ? version_definition : NULL;
-}
-
-const ElfW(Verdaux) *VDSOSupport::ElfMemImage::GetVerdefAux(
-    const ElfW(Verdef) *verdef) const {
-  return reinterpret_cast<const ElfW(Verdaux) *>(verdef+1);
-}
-
-const char *VDSOSupport::ElfMemImage::GetVerstr(ElfW(Word) offset) const {
-  CHECK_LT(offset, strsize_);
-  return dynstr_ + offset;
-}
-
-void VDSOSupport::ElfMemImage::Init(const void *base) {
-  ehdr_      = NULL;
-  dynsym_    = NULL;
-  dynstr_    = NULL;
-  versym_    = NULL;
-  verdef_    = NULL;
-  hash_      = NULL;
-  strsize_   = 0;
-  verdefnum_ = 0;
-  link_base_ = ~0L;  // Sentinel: PT_LOAD .p_vaddr can't possibly be this.
-  if (!base) {
-    return;
-  }
-  const intptr_t base_as_uintptr_t = reinterpret_cast<uintptr_t>(base);
-  // Fake VDSO has low bit set.
-  const bool fake_vdso = ((base_as_uintptr_t & 1) != 0);
-  base = reinterpret_cast<const void *>(base_as_uintptr_t & ~1);
-  const char *const base_as_char = reinterpret_cast<const char *>(base);
-  if (base_as_char[EI_MAG0] != ELFMAG0 || base_as_char[EI_MAG1] != ELFMAG1 ||
-      base_as_char[EI_MAG2] != ELFMAG2 || base_as_char[EI_MAG3] != ELFMAG3) {
-    RAW_DCHECK(false, "no ELF magic"); // at %p", base);
-    return;
-  }
-  int elf_class = base_as_char[EI_CLASS];
-  if (elf_class != CurrentElfClass::kElfClass) {
-    DCHECK_EQ(elf_class, CurrentElfClass::kElfClass);
-    return;
-  }
-  switch (base_as_char[EI_DATA]) {
-    case ELFDATA2LSB: {
-      if (__LITTLE_ENDIAN != __BYTE_ORDER) {
-        DCHECK_EQ(__LITTLE_ENDIAN, __BYTE_ORDER); // << ": wrong byte order";
-        return;
-      }
-      break;
-    }
-    case ELFDATA2MSB: {
-      if (__BIG_ENDIAN != __BYTE_ORDER) {
-        DCHECK_EQ(__BIG_ENDIAN, __BYTE_ORDER); // << ": wrong byte order";
-        return;
-      }
-      break;
-    }
-    default: {
-      RAW_DCHECK(false, "unexpected data encoding"); // << base_as_char[EI_DATA];
-      return;
-    }
-  }
-
-  ehdr_ = reinterpret_cast<const ElfW(Ehdr) *>(base);
-  const ElfW(Phdr) *dynamic_program_header = NULL;
-  for (int i = 0; i < ehdr_->e_phnum; ++i) {
-    const ElfW(Phdr) *const program_header = GetPhdr(i);
-    switch (program_header->p_type) {
-      case PT_LOAD:
-        if (link_base_ == ~0L) {
-          link_base_ = program_header->p_vaddr;
-        }
-        break;
-      case PT_DYNAMIC:
-        dynamic_program_header = program_header;
-        break;
-    }
-  }
-  if (link_base_ == ~0L || !dynamic_program_header) {
-    RAW_DCHECK(~0L != link_base_, "no PT_LOADs in VDSO");
-    RAW_DCHECK(dynamic_program_header, "no PT_DYNAMIC in VDSO");
-    // Mark this image as not present. Can not recur infinitely.
-    Init(0);
-    return;
-  }
-  std::ptrdiff_t relocation =
-      base_as_char - reinterpret_cast<const char *>(link_base_);
-  ElfW(Dyn) *dynamic_entry =
-      reinterpret_cast<ElfW(Dyn) *>(dynamic_program_header->p_vaddr +
-                                    relocation);
-  for (; dynamic_entry->d_tag != DT_NULL; ++dynamic_entry) {
-    ElfW(Xword) value = dynamic_entry->d_un.d_val;
-    if (fake_vdso) {
-      // A complication: in the real VDSO, dynamic entries are not relocated
-      // (it wasn't loaded by a dynamic loader). But when testing with a
-      // "fake" dlopen()ed vdso library, the loader relocates some (but
-      // not all!) of them before we get here.
-      if (dynamic_entry->d_tag == DT_VERDEF) {
-        // The only dynamic entry (of the ones we care about) libc-2.3.6
-        // loader doesn't relocate.
-        value += relocation;
-      }
-    } else {
-      // Real VDSO. Everything needs to be relocated.
-      value += relocation;
-    }
-    switch (dynamic_entry->d_tag) {
-      case DT_HASH:
-        hash_ = reinterpret_cast<ElfW(Word) *>(value);
-        break;
-      case DT_SYMTAB:
-        dynsym_ = reinterpret_cast<ElfW(Sym) *>(value);
-        break;
-      case DT_STRTAB:
-        dynstr_ = reinterpret_cast<const char *>(value);
-        break;
-      case DT_VERSYM:
-        versym_ = reinterpret_cast<ElfW(Versym) *>(value);
-        break;
-      case DT_VERDEF:
-        verdef_ = reinterpret_cast<ElfW(Verdef) *>(value);
-        break;
-      case DT_VERDEFNUM:
-        verdefnum_ = dynamic_entry->d_un.d_val;
-        break;
-      case DT_STRSZ:
-        strsize_ = dynamic_entry->d_un.d_val;
-        break;
-      default:
-        // Unrecognized entries explicitly ignored.
-        break;
-    }
-  }
-  if (!hash_ || !dynsym_ || !dynstr_ || !versym_ ||
-      !verdef_ || !verdefnum_ || !strsize_) {
-    RAW_DCHECK(hash_, "invalid VDSO (no DT_HASH)");
-    RAW_DCHECK(dynsym_, "invalid VDSO (no DT_SYMTAB)");
-    RAW_DCHECK(dynstr_, "invalid VDSO (no DT_STRTAB)");
-    RAW_DCHECK(versym_, "invalid VDSO (no DT_VERSYM)");
-    RAW_DCHECK(verdef_, "invalid VDSO (no DT_VERDEF)");
-    RAW_DCHECK(verdefnum_, "invalid VDSO (no DT_VERDEFNUM)");
-    RAW_DCHECK(strsize_, "invalid VDSO (no DT_STRSZ)");
-    // Mark this image as not present. Can not recur infinitely.
-    Init(0);
-    return;
-  }
-}
-
 VDSOSupport::VDSOSupport()
     // If vdso_base_ is still set to kInvalidBase, we got here
     // before VDSOSupport::Init has been called. Call it now.
-    : image_(vdso_base_ == kInvalidBase ? Init() : vdso_base_) {
+    : image_(vdso_base_ == ElfMemImage::kInvalidBase ? Init() : vdso_base_) {
 }
 
 // NOTE: we can't use GoogleOnceInit() below, because we can be
 // called by tcmalloc, and none of the *once* stuff may be functional yet.
 //
 // In addition, we hope that the VDSOSupportHelper constructor
 // causes this code to run before there are any threads, and before
 // InitGoogle() has executed any chroot or setuid calls.
 //
 // Finally, even if there is a race here, it is harmless, because
 // the operation should be idempotent.
 const void *VDSOSupport::Init() {
-  if (vdso_base_ == kInvalidBase) {
+  if (vdso_base_ == ElfMemImage::kInvalidBase) {
     // Valgrind zaps AT_SYSINFO_EHDR and friends from the auxv[]
     // on stack, and so glibc works as if VDSO was not present.
     // But going directly to kernel via /proc/self/auxv below bypasses
     // Valgrind zapping. So we check for Valgrind separately.
     if (RunningOnValgrind()) {
       vdso_base_ = NULL;
       getcpu_fn_ = &GetCPUViaSyscall;
       return NULL;
     }
     int fd = open("/proc/self/auxv", O_RDONLY);
     if (fd == -1) {
       // Kernel too old to have a VDSO.
       vdso_base_ = NULL;
       getcpu_fn_ = &GetCPUViaSyscall;
       return NULL;
     }
     ElfW(auxv_t) aux;
     while (read(fd, &aux, sizeof(aux)) == sizeof(aux)) {
       if (aux.a_type == AT_SYSINFO_EHDR) {
         COMPILE_ASSERT(sizeof(vdso_base_) == sizeof(aux.a_un.a_val),
                        unexpected_sizeof_pointer_NE_sizeof_a_val);
         vdso_base_ = reinterpret_cast<void *>(aux.a_un.a_val);
         break;
       }
     }
     close(fd);
-    if (vdso_base_ == kInvalidBase) {
+    if (vdso_base_ == ElfMemImage::kInvalidBase) {
       // Didn't find AT_SYSINFO_EHDR in auxv[].
       vdso_base_ = NULL;
     }
   }
   GetCpuFn fn = &GetCPUViaSyscall;  // default if VDSO not present.
   if (vdso_base_) {
     VDSOSupport vdso;
     SymbolInfo info;
     if (vdso.LookupSymbol("__vdso_getcpu", "LINUX_2.6", STT_FUNC, &info)) {
       // Casting from an int to a pointer is not legal C++.  To emphasize
       // this, we use a C-style cast rather than a C++-style cast.
       fn = (GetCpuFn)(info.address);
     }
   }
   // Subtle: this code runs outside of any locks; prevent compiler
   // from assigning to getcpu_fn_ more than once.
   base::subtle::MemoryBarrier();
   getcpu_fn_ = fn;
   return vdso_base_;
 }
 
 const void *VDSOSupport::SetBase(const void *base) {
+  CHECK(base != ElfMemImage::kInvalidBase);
   const void *old_base = vdso_base_;
   vdso_base_ = base;
   image_.Init(base);
   // Also reset getcpu_fn_, so GetCPU could be tested with simulated VDSO.
   getcpu_fn_ = &InitAndGetCPU;
   return old_base;
 }
 
 bool VDSOSupport::LookupSymbol(const char *name,
                                const char *version,
                                int type,
                                SymbolInfo *info) const {
-  for (SymbolIterator it = begin(); it != end(); ++it) {
-    if (strcmp(it->name, name) == 0 && strcmp(it->version, version) == 0 &&
-        CurrentElfClass::ElfType(it->symbol) == type) {
-      if (info) {
-        *info = *it;
-      }
-      return true;
-    }
-  }
-  return false;
+  return image_.LookupSymbol(name, version, type, info);
 }
 
 bool VDSOSupport::LookupSymbolByAddress(const void *address,
                                         SymbolInfo *info_out) const {
-  for (SymbolIterator it = begin(); it != end(); ++it) {
-    const char *const symbol_start =
-        reinterpret_cast<const char *>(it->address);
-    const char *const symbol_end = symbol_start + it->symbol->st_size;
-    if (symbol_start <= address && address < symbol_end) {
-      if (info_out) {
-        // Client wants to know details for that symbol (the usual case).
-        if (CurrentElfClass::ElfBind(it->symbol) == STB_GLOBAL) {
-          // Strong symbol; just return it.
-          *info_out = *it;
-          return true;
-        } else {
-          // Weak or local. Record it, but keep looking for a strong one.
-          *info_out = *it;
-        }
-      } else {
-        // Client only cares if there is an overlapping symbol.
-        return true;
-      }
-    }
-  }
-  return false;
-}
-
-VDSOSupport::SymbolIterator::SymbolIterator(const void *const image, int index)
-    : index_(index), image_(image) {
-}
-
-const VDSOSupport::SymbolInfo *VDSOSupport::SymbolIterator::operator->() const {
-  return &info_;
-}
-
-const VDSOSupport::SymbolInfo& VDSOSupport::SymbolIterator::operator*() const {
-  return info_;
-}
-
-bool VDSOSupport::SymbolIterator::operator==(const SymbolIterator &rhs) const {
-  return this->image_ == rhs.image_ && this->index_ == rhs.index_;
-}
-
-bool VDSOSupport::SymbolIterator::operator!=(const SymbolIterator &rhs) const {
-  return !(*this == rhs);
-}
-
-VDSOSupport::SymbolIterator &VDSOSupport::SymbolIterator::operator++() {
-  this->Update(1);
-  return *this;
-}
-
-VDSOSupport::SymbolIterator VDSOSupport::begin() const {
-  SymbolIterator it(&image_, 0);
-  it.Update(0);
-  return it;
-}
-
-VDSOSupport::SymbolIterator VDSOSupport::end() const {
-  return SymbolIterator(&image_, image_.GetNumSymbols());
-}
-
-void VDSOSupport::SymbolIterator::Update(int increment) {
-  const ElfMemImage *image = reinterpret_cast<const ElfMemImage *>(image_);
-  CHECK(image->IsPresent() || increment == 0);
-  if (!image->IsPresent()) {
-    return;
-  }
-  index_ += increment;
-  if (index_ >= image->GetNumSymbols()) {
-    index_ = image->GetNumSymbols();
-    return;
-  }
-  const ElfW(Sym)    *symbol = image->GetDynsym(index_);
-  const ElfW(Versym) *version_symbol = image->GetVersym(index_);
-  CHECK(symbol && version_symbol);
-  const char *const symbol_name = image->GetDynstr(symbol->st_name);
-  const ElfW(Versym) version_index = version_symbol[0] & VERSYM_VERSION;
-  const ElfW(Verdef) *version_definition = NULL;
-  const char *version_name = "";
-  if (symbol->st_shndx == SHN_UNDEF) {
-    // Undefined symbols reference DT_VERNEED, not DT_VERDEF, and
-    // version_index could well be greater than verdefnum_, so calling
-    // GetVerdef(version_index) may trigger assertion.
-  } else {
-    version_definition = image->GetVerdef(version_index);
-  }
-  if (version_definition) {
-    // I am expecting 1 or 2 auxiliary entries: 1 for the version itself,
-    // optional 2nd if the version has a parent.
-    CHECK_LE(1, version_definition->vd_cnt);
-    CHECK_LE(version_definition->vd_cnt, 2);
-    const ElfW(Verdaux) *version_aux = image->GetVerdefAux(version_definition);
-    version_name = image->GetVerstr(version_aux->vda_name);
-  }
-  info_.name    = symbol_name;
-  info_.version = version_name;
-  info_.address = image->GetSymAddr(symbol);
-  info_.symbol  = symbol;
+  return image_.LookupSymbolByAddress(address, info_out);
 }
 
 // NOLINT on 'long' because this routine mimics kernel api.
 long VDSOSupport::GetCPUViaSyscall(unsigned *cpu, void *, void *) { // NOLINT
 #if defined(__NR_getcpu)
   return sys_getcpu(cpu, NULL, NULL);
 #else
   // x86_64 never implemented sys_getcpu(), except as a VDSO call.
   errno = ENOSYS;
   return -1;
@@ skipping 24 matching lines @@
 // ensure it here, with a global constructor of our own.  This
 // is an allowed exception to the normal rule against non-trivial
 // global constructors.
 static class VDSOInitHelper {
  public:
   VDSOInitHelper() { VDSOSupport::Init(); }
 } vdso_init_helper;
 }
 
 #endif  // HAVE_VDSO_SUPPORT