platform-linux-lul.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <stdio.h>

#include <signal.h>

#include <string.h>

#include <stdlib.h>

#include <time.h>

#include "mozilla/ProfilerState.h"

#include "platform.h"

#include "PlatformMacros.h"

#include "LulMain.h"

#include "SharedLibraries.h"

#include "AutoObjectMapper.h"

// Contains miscellaneous helpers that are used to connect the Gecko Profiler

// and LUL.

// Find out, in a platform-dependent way, where the code modules got

// mapped in the process' virtual address space, and get |aLUL| to

// load unwind info for them.

void read_procmaps(lul::LUL* aLUL) {

  MOZ_ASSERT(aLUL->CountMappings() == 0);

#if defined(GP_OS_linux) || defined(GP_OS_android) || defined(GP_OS_freebsd)

  SharedLibraryInfo info = SharedLibraryInfo::GetInfoForSelf();

  for (size_t i = 0; i < info.GetSize(); i++) {

    const SharedLibrary& lib = info.GetEntry(i);

    std::string nativePath = lib.GetDebugPath();

    // We can use the standard POSIX-based mapper.

    AutoObjectMapperPOSIX mapper(aLUL->mLog);

    // Ask |mapper| to map the object.  Then hand its mapped address

    // to NotifyAfterMap().

    void* image = nullptr;

    size_t size = 0;

    bool ok = mapper.Map(&image, &size, nativePath);

    if (ok && image && size > 0) {

      aLUL->NotifyAfterMap(lib.GetStart(), lib.GetEnd() - lib.GetStart(),

                           nativePath.c_str(), image);

    } else if (!ok && lib.GetDebugName().empty()) {

      // The object has no name and (as a consequence) the mapper failed to map

      // it.  This happens on Linux, where GetInfoForSelf() produces such a

      // mapping for the VDSO.  This is a problem on x86-{linux,android} because

      // lack of knowledge about the mapped area inhibits LUL's special

      // __kernel_syscall handling.  Hence notify |aLUL| at least of the

      // mapping, even though it can't read any unwind information for the area.

      aLUL->NotifyExecutableArea(lib.GetStart(), lib.GetEnd() - lib.GetStart());

    // |mapper| goes out of scope at this point and so its destructor

    // unmaps the object.

#else

#  error "Unknown platform"

#endif

// LUL needs a callback for its logging sink.

void logging_sink_for_LUL(const char* str) {

  // These are only printed when Verbose logging is enabled (e.g. with

  // MOZ_LOG="prof:5"). This is because LUL's logging is much more verbose than

  // the rest of the profiler's logging, which occurs at the Info (3) and Debug

  // (4) levels.

  MOZ_LOG(gProfilerLog, mozilla::LogLevel::Verbose,

          ("[%" PRIu64 "] %s",

           uint64_t(profiler_current_process_id().ToNumber()), str));