tools/profiler/core/ProfilerCodeAddressService.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "ProfilerCodeAddressService.h"
   8
   9 #include "platform.h"
  10 #include "mozilla/StackWalk.h"
  11
  12 using namespace mozilla;
  13
  14 #if defined(XP_LINUX) || defined(XP_FREEBSD)
  15 static char* SearchSymbolTable(SymbolTable& aTable, uint32_t aOffset) {
  16   size_t index;
  17   bool exact =
  18       BinarySearch(aTable.mAddrs, 0, aTable.mAddrs.Length(), aOffset, &index);
  19
  20   if (index == 0 && !exact) {
  21     // Our offset is before the first symbol in the table; no result.
  22     return nullptr;
  23   }
  24
  25   // Extract the (mangled) symbol name out of the string table.
  26   auto strings = reinterpret_cast<char*>(aTable.mBuffer.Elements());
  27   nsCString symbol;
  28   symbol.Append(strings + aTable.mIndex[index - 1],
  29                 aTable.mIndex[index] - aTable.mIndex[index - 1]);
  30
  31   // First try demangling as a Rust identifier.
  32   char demangled[1024];
  33   if (!profiler_demangle_rust(symbol.get(), demangled, std::size(demangled))) {
  34     // Then as a C++ identifier.
  35     DemangleSymbol(symbol.get(), demangled, std::size(demangled));
  36   }
  37   demangled[std::size(demangled) - 1] = '\0';
  38
  39   // Use the mangled name if we didn't successfully demangle.
  40   return strdup(demangled[0] != '\0' ? demangled : symbol.get());
  41 }
  42 #endif
  43
  44 bool ProfilerCodeAddressService::GetFunction(const void* aPc,
  45                                              nsACString& aResult) {
  46   Entry& entry = GetEntry(aPc);
  47
  48 #if defined(XP_LINUX) || defined(XP_FREEBSD)
  49   // On Linux, most symbols will not be found by the MozDescribeCodeAddress call
  50   // that GetEntry does.  So we read the symbol table directly from the ELF
  51   // image.
  52
  53   // SymbolTable currently assumes library offsets will not be larger than
  54   // 4 GiB.
  55   if (entry.mLOffset <= 0xFFFFFFFF && !entry.mFunction) {
  56     auto p = mSymbolTables.lookupForAdd(entry.mLibrary);
  57     if (!p) {
  58       if (!mSymbolTables.add(p, entry.mLibrary, SymbolTable())) {
  59         MOZ_CRASH("ProfilerCodeAddressService OOM");
  60       }
  61       profiler_get_symbol_table(entry.mLibrary, nullptr, &p->value());
  62     }
  63     entry.mFunction =
  64         SearchSymbolTable(p->value(), static_cast<uint32_t>(entry.mLOffset));
  65   }
  66 #endif
  67
  68   if (!entry.mFunction || entry.mFunction[0] == '\0') {
  69     return false;
  70   }
  71
  72   aResult = nsDependentCString(entry.mFunction);
  73   return true;
  74 }