Merging upstream version 127.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

15 files changed, 496 insertions, 91 deletions

diff --git a/tools/profiler/core/memory_hooks.cpp b/tools/profiler/core/memory_hooks.cpp
index e13a109aab..5167d15d46 100644
--- a/tools/profiler/core/memory_hooks.cpp
+++ b/tools/profiler/core/memory_hooks.cpp
@@ -584,6 +584,7 @@ BaseProfilerCount* install_memory_hooks() {
     ThreadIntercept::Init();
   } else {
     sCounter->Clear();
+    sCounter->Register();
   }
   jemalloc_replace_dynamic(replace_init);
   return sCounter;
@@ -635,4 +636,10 @@ void disable_native_allocations() {
   }
 }
 
+void unregister_memory_counter() {
+  if (sCounter) {
+    sCounter->Unregister();
+  }
+}
+
 }  // namespace mozilla::profiler
diff --git a/tools/profiler/core/memory_hooks.h b/tools/profiler/core/memory_hooks.h
index a6ace771dd..4f59b21136 100644
--- a/tools/profiler/core/memory_hooks.h
+++ b/tools/profiler/core/memory_hooks.h
@@ -17,6 +17,7 @@ BaseProfilerCount* install_memory_hooks();
 void remove_memory_hooks();
 void enable_native_allocations();
 void disable_native_allocations();
+void unregister_memory_counter();
 
 }  // namespace profiler
 }  // namespace mozilla
diff --git a/tools/profiler/core/platform.cpp b/tools/profiler/core/platform.cpp
index 6b7e318f80..4641587a9a 100644
--- a/tools/profiler/core/platform.cpp
+++ b/tools/profiler/core/platform.cpp
@@ -114,18 +114,32 @@
 #include <string_view>
 #include <type_traits>
 
+// To simplify other code in this file, define a helper definition to avoid
+// repeating the same preprocessor checks.
+
 // The signals that we use to control the profiler conflict with the signals
-// used to control the code coverage tool. Therefore, if coverage is enabled, we
-// need to disable our own signal handling mechanisms.
+// used to control the code coverage tool. Therefore, if coverage is enabled,
+// we need to disable our own signal handling mechanisms.
 #ifndef MOZ_CODE_COVERAGE
 #  ifdef XP_WIN
 // TODO: Add support for windows "signal"-like behaviour. See Bug 1867328.
+#  elif defined(GP_OS_darwin) || defined(GP_OS_linux) || \
+      defined(GP_OS_android) || defined(GP_OS_freebsd)
+// Specify the specific platforms that we want to support
+#    define GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL 1
 #  else
-#    include <signal.h>
-#    include <unistd.h>
+// No support on this unknown platform!
 #  endif
 #endif
 
+// We need some extra includes if we're supporting async posix signals
+#if defined(GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL)
+#  include <signal.h>
+#  include <fcntl.h>
+#  include <unistd.h>
+#  include <errno.h>
+#endif
+
 #if defined(GP_OS_android)
 #  include "JavaExceptions.h"
 #  include "mozilla/java/GeckoJavaSamplerNatives.h"
@@ -250,11 +264,28 @@ ProfileChunkedBuffer& profiler_get_core_buffer() {
   return sProfileChunkedBuffer;
 }
 
-mozilla::Atomic<int, mozilla::MemoryOrdering::Relaxed> gSkipSampling;
+#if defined(GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL)
+// Control character to start the profiler ('g' for "go"!)
+static const char sAsyncSignalControlCharStart = 'g';
+// Control character to stop the profiler ('s' for "stop"!)
+static const char sAsyncSignalControlCharStop = 's';
+
+// This is a file descriptor that is the "write" end of the POSIX pipe that we
+// use to start the profiler. It is written to in profiler_start_signal_handler
+// and read from in AsyncSignalControlThread
+static mozilla::Atomic<int, mozilla::MemoryOrdering::Relaxed>
+    sAsyncSignalControlWriteFd(-1);
 
 // Atomic flag to stop the profiler from within the sampling loop
 mozilla::Atomic<bool, mozilla::MemoryOrdering::Relaxed> gStopAndDumpFromSignal(
     false);
+#endif
+
+// Forward declare the function to call when we need to dump + stop from within
+// the async control thread
+void profiler_dump_and_stop();
+
+mozilla::Atomic<int, mozilla::MemoryOrdering::Relaxed> gSkipSampling;
 
 #if defined(GP_OS_android)
 class GeckoJavaSampler
@@ -380,6 +411,7 @@ static uint32_t AvailableFeatures() {
   }
 #else
   // The memory hooks are not available.
+  ProfilerFeature::ClearMemory(features);
   ProfilerFeature::ClearNativeAllocations(features);
 #endif
 
@@ -506,6 +538,143 @@ static constexpr size_t MAX_JS_FRAMES =
 using JsFrame = mozilla::profiler::ThreadRegistrationData::JsFrame;
 using JsFrameBuffer = mozilla::profiler::ThreadRegistrationData::JsFrameBuffer;
 
+#if defined(GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL)
+// Forward declare this, so we can call it from the constructor.
+static void* AsyncSignalControlThreadEntry(void* aArg);
+
+// Define our platform specific async (posix) signal control thread here.
+class AsyncSignalControlThread {
+ public:
+  AsyncSignalControlThread() : mThread() {
+    // Try to open a pipe for this to communicate with. If we can't do this,
+    // then we give up and return, as there's no point continuing without
+    // being able to communicate
+    int pipeFds[2];
+    if (pipe(pipeFds)) {
+      LOG("Profiler AsyncSignalControlThread failed to create a pipe.");
+      return;
+    }
+
+    // Close this pipe on calls to exec().
+    fcntl(pipeFds[0], F_SETFD, FD_CLOEXEC);
+    fcntl(pipeFds[1], F_SETFD, FD_CLOEXEC);
+
+    // Write the reading side to mFd, and the writing side to the global atomic
+    mFd = pipeFds[0];
+    sAsyncSignalControlWriteFd = pipeFds[1];
+
+    // We don't really care about stack size, as it should be minimal, so
+    // leave the pthread attributes as a nullptr, i.e. choose the default.
+    pthread_attr_t* attr_ptr = nullptr;
+    if (pthread_create(&mThread, attr_ptr, AsyncSignalControlThreadEntry,
+                       this) != 0) {
+      MOZ_CRASH("pthread_create failed");
+    }
+  };
+
+  ~AsyncSignalControlThread() {
+    // Derived from code in nsDumpUtils.cpp. Comment reproduced here for
+    // poisterity: Close sAsyncSignalControlWriteFd /after/ setting the fd to
+    // -1. Otherwise we have the (admittedly far-fetched) race where we
+    //
+    //  1) close sAsyncSignalControlWriteFd
+    //  2) open a new fd with the same number as sAsyncSignalControlWriteFd
+    //     had.
+    //  3) receive a signal, then write to the fd.
+    int asyncSignalControlWriteFd = sAsyncSignalControlWriteFd.exchange(-1);
+    // This will unblock the "read" in StartWatching.
+    close(asyncSignalControlWriteFd);
+    // Finally, exit the thread.
+    pthread_join(mThread, nullptr);
+  };
+
+  void Watch() {
+    char msg[1];
+    ssize_t nread;
+    while (true) {
+      // Try reading from the pipe. This will block until something is written:
+      nread = read(mFd, msg, sizeof(msg));
+
+      if (nread == -1 && errno == EINTR) {
+        // nread == -1 and errno == EINTR means that `read` was interrupted
+        // by a signal before reading any data. This is likely because the
+        // profiling thread interrupted us (with SIGPROF). We can safely ignore
+        // this and "go around" the loop again to try and read.
+        continue;
+      }
+
+      if (nread == -1 && errno != EINTR) {
+        // nread == -1 and errno != EINTR means that `read` has failed in some
+        // way that we can't recover from. In this case, all we can do is give
+        // up, and quit the watcher, as the pipe is likely broken.
+        LOG("Error (%d) when reading in AsyncSignalControlThread", errno);
+        return;
+      }
+
+      if (nread == 0) {
+        // nread == 0 signals that the other end of the pipe has been cleanly
+        // closed. Close our end, and exit the reading loop.
+        close(mFd);
+        return;
+      }
+
+      // If we reach here, nread != 0 and nread != -1. This means that we
+      // should have read at least one byte, which should be a control byte
+      // for the profiler.
+      // It *might* happen that `read` is interrupted by the sampler thread
+      // after successfully reading. If this occurs, read returns the number
+      // of bytes read. As anything other than 1 is wrong for us, we can
+      // always assume that we can read whatever `read` read.
+      MOZ_RELEASE_ASSERT(nread == 1);
+
+      if (msg[0] == sAsyncSignalControlCharStart) {
+        // Start the profiler here directly, as we're on a background thread.
+        // set of preferences, configuration of them is TODO, see Bug 1866007
+        uint32_t features = ProfilerFeature::JS | ProfilerFeature::StackWalk |
+                            ProfilerFeature::CPUUtilization;
+        // as we often don't know what threads we'll care about, tell the
+        // profiler to profile all threads.
+        const char* filters[] = {"*"};
+        profiler_start(PROFILER_DEFAULT_SIGHANDLE_ENTRIES,
+                       PROFILER_DEFAULT_INTERVAL, features, filters,
+                       MOZ_ARRAY_LENGTH(filters), 0);
+      } else if (msg[0] == sAsyncSignalControlCharStop) {
+        // Check to see whether the profiler is even running before trying to
+        // stop the profiler. Most other methods of stopping the profiler (i.e.
+        // those through nsProfiler etc) already know whether or not the
+        // profiler is running, so don't try and stop it if it's already
+        // running. Signal-stopping doesn't have this constraint, so we should
+        // check just in case there is a codepath followed by
+        // `profiler_dump_and_stop` that breaks if we stop while stopped.
+        if (profiler_is_active()) {
+          profiler_dump_and_stop();
+        }
+      } else {
+        LOG("AsyncSignalControlThread recieved unknown control signal: %c",
+            msg[0]);
+      }
+    }
+  };
+
+ private:
+  // The read side of the pipe that we use to communicate from a signal handler
+  // to the AsyncSignalControlThread
+  int mFd;
+
+  // The thread handle for the async signal control thread
+  // Note, that unlike the sampler thread, this is currently a posix-only
+  // feature. Therefore, we don't bother to have a windows equivalent - we
+  // just use a pthread_t
+  pthread_t mThread;
+};
+
+static void* AsyncSignalControlThreadEntry(void* aArg) {
+  auto* thread = static_cast<AsyncSignalControlThread*>(aArg);
+  thread->Watch();
+  return nullptr;
+}
+#endif
+
 // All functions in this file can run on multiple threads unless they have an
 // NS_IsMainThread() assertion.
 
@@ -529,6 +698,10 @@ class CorePS {
   CorePS()
       : mProcessStartTime(TimeStamp::ProcessCreation()),
         mMaybeBandwidthCounter(nullptr)
+#if defined(GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL)
+        ,
+        mAsyncSignalControlThread(nullptr)
+#endif
 #ifdef USE_LUL_STACKWALK
         ,
         mLul(nullptr)
@@ -539,6 +712,9 @@ class CorePS {
   }
 
   ~CorePS() {
+#if defined(GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL)
+    delete mAsyncSignalControlThread;
+#endif
 #ifdef USE_LUL_STACKWALK
     delete sInstance->mLul;
     delete mMaybeBandwidthCounter;
@@ -684,6 +860,14 @@ class CorePS {
     return sInstance->mMaybeBandwidthCounter;
   }
 
+#if defined(GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL)
+  static void SetAsyncSignalControlThread(
+      AsyncSignalControlThread* aAsyncSignalControlThread) {
+    MOZ_ASSERT(sInstance);
+    sInstance->mAsyncSignalControlThread = aAsyncSignalControlThread;
+  }
+#endif
+
  private:
   // The singleton instance
   static CorePS* sInstance;
@@ -701,6 +885,11 @@ class CorePS {
   // Non-owning pointers to all active counters
   Vector<BaseProfilerCount*> mCounters;
 
+#if defined(GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL)
+  // Background thread for communicating with async signal handlers
+  AsyncSignalControlThread* mAsyncSignalControlThread;
+#endif
+
 #ifdef USE_LUL_STACKWALK
   // LUL's state. Null prior to the first activation, non-null thereafter.
   // Owned by this CorePS.
@@ -1139,6 +1328,11 @@ class ActivePS {
 
 #undef PS_GET_FEATURE
 
+  static bool ShouldInstallMemoryHooks(PSLockRef) {
+    MOZ_ASSERT(sInstance);
+    return ProfilerFeature::ShouldInstallMemoryHooks(sInstance->mFeatures);
+  }
+
   static uint32_t JSFlags(PSLockRef aLock) {
     uint32_t Flags = 0;
     Flags |=
@@ -4106,10 +4300,6 @@ static SamplerThread* NewSamplerThread(PSLockRef aLock, uint32_t aGeneration,
   return new SamplerThread(aLock, aGeneration, aInterval, aFeatures);
 }
 
-// Forward declare the function to call when we need to dump + stop from within
-// the sampler thread
-void profiler_dump_and_stop();
-
 // This function is the sampler thread.  This implementation is used for all
 // targets.
 void SamplerThread::Run() {
@@ -4765,27 +4955,6 @@ void SamplerThread::Run() {
       scheduledSampleStart = beforeSleep + sampleInterval;
       SleepMicro(static_cast<uint32_t>(sampleInterval.ToMicroseconds()));
     }
-
-    // Check to see if the hard-reset flag has been set to stop the profiler.
-    // This should only be used on the worst occasions when we need to stop the
-    // profiler from within the sampling thread (e.g. if the main thread is
-    // stuck) We need to do this here as it is outside of the scope of the lock.
-    // Otherwise we'll encounter a race condition where `profiler_stop` tries to
-    // get the lock that we already hold. We also need to wait until after we
-    // have carried out post sampling callbacks, as otherwise we may reach a
-    // situation where another part of the program is waiting for us to finish
-    // sampling, but we have ended early!
-    if (gStopAndDumpFromSignal) {
-      // Reset the flag in case we restart the profiler at a later point
-      gStopAndDumpFromSignal = false;
-      // dump the profile, and stop the profiler
-      profiler_dump_and_stop();
-      // profiler_stop will try to destroy the active sampling thread. This will
-      // also destroy some data structures that are used further down this
-      // function, leading to invalid accesses. We therefore exit the function
-      // directly, rather than breaking from the loop.
-      return;
-    }
   }
 
   // End of `while` loop. We can only be here from a `break` inside the loop.
@@ -5069,9 +5238,9 @@ void SamplerThread::SpyOnUnregisteredThreads() {
 
 MOZ_DEFINE_MALLOC_SIZE_OF(GeckoProfilerMallocSizeOf)
 
-NS_IMETHODIMP
-GeckoProfilerReporter::CollectReports(nsIHandleReportCallback* aHandleReport,
-                                      nsISupports* aData, bool aAnonymize) {
+NS_IMETHODIMP GeckoProfilerReporter::CollectReports(
+    nsIHandleReportCallback* aHandleReport, nsISupports* aData,
+    bool aAnonymize) {
   MOZ_RELEASE_ASSERT(NS_IsMainThread());
 
   size_t profSize = 0;
@@ -5294,16 +5463,41 @@ static const char* get_size_suffix(const char* str) {
   return ptr;
 }
 
-#if !defined(XP_WIN) && !defined(MOZ_CODE_COVERAGE)
+#if defined(GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL)
+static void profiler_start_signal_handler(int signal, siginfo_t* info,
+                                          void* context) {
+  // Starting the profiler from a signal handler is a risky business: Both of
+  // the main tasks that we would like to accomplish (allocating memory, and
+  // starting a thread) are illegal within a UNIX signal handler. Conversely,
+  // we cannot dispatch to the main thread, as this may be "stuck" (why else
+  // would we be using a signal handler to start the profiler?).
+  // Instead, we have a background thread running that watches a pipe for a
+  // given "control" character. In this handler, we can simply write to that
+  // pipe to get the background thread to start the profiler for us!
+  // Note that `write` is async-signal safe (see signal-safety(7)):
+  // https://www.man7.org/linux/man-pages/man7/signal-safety.7.html
+  // This means that it's safe for us to call within a signal handler.
+  if (sAsyncSignalControlWriteFd != -1) {
+    char signalControlCharacter = sAsyncSignalControlCharStart;
+    Unused << write(sAsyncSignalControlWriteFd, &signalControlCharacter,
+                    sizeof(signalControlCharacter));
+  }
+}
+
 static void profiler_stop_signal_handler(int signal, siginfo_t* info,
                                          void* context) {
-  // We cannot really do any logging here, as this is a signal handler.
   // Signal handlers are limited in what functions they can call, for more
   // details see: https://man7.org/linux/man-pages/man7/signal-safety.7.html
-  // Writing to a file is allowed, but as signal handlers are also limited in
-  // how long they can run, we instead set an atomic variable to true to trigger
-  // the sampling thread to stop and dump the data in the profiler.
-  gStopAndDumpFromSignal = true;
+  // As we have a background thread already running for checking whether or
+  // not we want to start the profiler, we can re-use the same machinery to
+  // stop the profiler. We use the same mechanism of writing to a pipe/file
+  // descriptor, but with a different control character. Note that `write` is
+  // signal safe.
+  if (sAsyncSignalControlWriteFd != -1) {
+    char signalControlCharacter = sAsyncSignalControlCharStop;
+    Unused << write(sAsyncSignalControlWriteFd, &signalControlCharacter,
+                    sizeof(signalControlCharacter));
+  }
 }
 #endif
 
@@ -5379,8 +5573,17 @@ void profiler_dump_and_stop() {
   profiler_stop();
 }
 
+#if defined(GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL)
 void profiler_init_signal_handlers() {
-#if !defined(XP_WIN) && !defined(MOZ_CODE_COVERAGE)
+  // Set a handler to start the profiler
+  struct sigaction prof_start_sa {};
+  memset(&prof_start_sa, 0, sizeof(struct sigaction));
+  prof_start_sa.sa_sigaction = profiler_start_signal_handler;
+  prof_start_sa.sa_flags = SA_RESTART | SA_SIGINFO;
+  sigemptyset(&prof_start_sa.sa_mask);
+  DebugOnly<int> rstart = sigaction(SIGUSR1, &prof_start_sa, nullptr);
+  MOZ_ASSERT(rstart == 0, "Failed to install Profiler SIGUSR1 handler");
+
   // Set a handler to stop the profiler
   struct sigaction prof_stop_sa {};
   memset(&prof_stop_sa, 0, sizeof(struct sigaction));
@@ -5389,8 +5592,8 @@ void profiler_init_signal_handlers() {
   sigemptyset(&prof_stop_sa.sa_mask);
   DebugOnly<int> rstop = sigaction(SIGUSR2, &prof_stop_sa, nullptr);
   MOZ_ASSERT(rstop == 0, "Failed to install Profiler SIGUSR2 handler");
-#endif
 }
+#endif
 
 void profiler_init(void* aStackTop) {
   LOG("profiler_init");
@@ -5444,8 +5647,14 @@ void profiler_init(void* aStackTop) {
     // Platform-specific initialization.
     PlatformInit(lock);
 
+#if defined(GECKO_PROFILER_ASYNC_POSIX_SIGNAL_CONTROL)
+    // Initialise the background thread to listen for signal handler
+    // communication
+    CorePS::SetAsyncSignalControlThread(new AsyncSignalControlThread);
+
     // Initialise the signal handlers needed to start/stop the profiler
     profiler_init_signal_handlers();
+#endif
 
 #if defined(GP_OS_android)
     if (jni::IsAvailable()) {
@@ -5611,9 +5820,16 @@ void profiler_init(void* aStackTop) {
   profiler_mark_thread_awake();
 
 #if defined(MOZ_REPLACE_MALLOC) && defined(MOZ_PROFILER_MEMORY)
-  // Start counting memory allocations (outside of lock because this may call
-  // profiler_add_sampled_counter which would attempt to take the lock.)
-  ActivePS::SetMemoryCounter(mozilla::profiler::install_memory_hooks());
+  if (ProfilerFeature::ShouldInstallMemoryHooks(features)) {
+    // Start counting memory allocations (outside of lock because this may call
+    // profiler_add_sampled_counter which would attempt to take the lock.)
+    ActivePS::SetMemoryCounter(mozilla::profiler::install_memory_hooks());
+  } else {
+    // Unregister the memory counter in case it was registered before. This will
+    // make sure that the empty memory counter from the previous profiler run is
+    // removed completely and we don't serialize the memory counters.
+    mozilla::profiler::unregister_memory_counter();
+  }
 #endif
 
   invoke_profiler_state_change_callbacks(ProfilingState::Started);
@@ -6240,9 +6456,16 @@ RefPtr<GenericPromise> profiler_start(PowerOfTwo32 aCapacity, double aInterval,
   }
 
 #if defined(MOZ_REPLACE_MALLOC) && defined(MOZ_PROFILER_MEMORY)
-  // Start counting memory allocations (outside of lock because this may call
-  // profiler_add_sampled_counter which would attempt to take the lock.)
-  ActivePS::SetMemoryCounter(mozilla::profiler::install_memory_hooks());
+  if (ProfilerFeature::ShouldInstallMemoryHooks(aFeatures)) {
+    // Start counting memory allocations (outside of lock because this may call
+    // profiler_add_sampled_counter which would attempt to take the lock.)
+    ActivePS::SetMemoryCounter(mozilla::profiler::install_memory_hooks());
+  } else {
+    // Unregister the memory counter in case it was registered before. This will
+    // make sure that the empty memory counter from the previous profiler run is
+    // removed completely and we don't serialize the memory counters.
+    mozilla::profiler::unregister_memory_counter();
+  }
 #endif
 
   invoke_profiler_state_change_callbacks(ProfilingState::Started);
@@ -6366,7 +6589,8 @@ void profiler_ensure_started(PowerOfTwo32 aCapacity, double aInterval,
   }
 
 #if defined(MOZ_REPLACE_MALLOC) && defined(MOZ_PROFILER_MEMORY)
-  if (ActivePS::FeatureNativeAllocations(aLock)) {
+  if (ActivePS::FeatureNativeAllocations(aLock) &&
+      ActivePS::ShouldInstallMemoryHooks(aLock)) {
     mozilla::profiler::disable_native_allocations();
   }
 #endif
diff --git a/tools/profiler/docs/code-overview.rst b/tools/profiler/docs/code-overview.rst
index 3ca662e141..bb9db364de 100644
--- a/tools/profiler/docs/code-overview.rst
+++ b/tools/profiler/docs/code-overview.rst
@@ -2,7 +2,7 @@ Profiler Code Overview
 ######################
 
 This is an overview of the code that implements the Profiler inside Firefox
-with dome details around tricky subjects, or pointers to more detailed
+with some details around tricky subjects, or pointers to more detailed
 documentation and/or source code.
 
 It assumes familiarity with Firefox development, including Mercurial (hg), mach,
diff --git a/tools/profiler/docs/index.rst b/tools/profiler/docs/index.rst
index 53920e7d2f..02eb9f6839 100644
--- a/tools/profiler/docs/index.rst
+++ b/tools/profiler/docs/index.rst
@@ -23,13 +23,13 @@ while the profiler.firefox.com interface is documented at `profiler.firefox.com/
    buffer
    instrumenting-javascript
    instrumenting-rust
+   instrumenting-android
    markers-guide
    memory
 
 The following areas still need documentation:
 
  * LUL
- * Instrumenting Java
  * Registering Threads
  * Samples and Stack Walking
  * Triggering Gecko Profiles in Automation
diff --git a/tools/profiler/docs/instrumenting-android.rst b/tools/profiler/docs/instrumenting-android.rst
new file mode 100644
index 0000000000..fdd96613b4
--- /dev/null
+++ b/tools/profiler/docs/instrumenting-android.rst
@@ -0,0 +1,102 @@
+Instrumenting Android
+========================
+
+There are multiple ways to use the profiler with Android. There is the "Java"
+profiler feature (via about:profiling), which enables profiling for JVM code.
+This is most likely turned on already for the preset if you are profiling an
+Android device.
+
+In addition to sampling, markers can be created to specifically mark an instant
+in time, or a duration. This can be helpful to make sense of a particular piece
+of the front-end, or record events that normally wouldn't show up in samples.
+
+.. note::
+    This guide explains Android markers in depth. To learn more about how to add a
+    marker in C++, JavaScript or Rust, please take a look at their documentation
+    in :doc:`markers-guide`, :doc:`instrumenting-javascript` or
+    :doc:`instrumenting-rust` respectively.
+
+Markers in the GeckoView Java codebase
+**************************************
+
+If you are in the GeckoView codebase, then you should have access to ``GeckoRuntime``.
+``GeckoRuntime`` has a ``getProfilerController`` method to get the ``ProfilerController``.
+See the `ProfilerController Java file`_ (`javadoc`_) to find which methods you can use to
+instrument your source code.
+
+Here's an example:
+
+.. code-block:: java
+
+    // Simple marker
+    sGeckoRuntime.getProfilerController().addMarker("Marker Name");
+
+    // Simple marker with additional information
+    sGeckoRuntime.getProfilerController().addMarker("Marker Name", "info");
+
+    // Duration marker
+    Double startTime = sGeckoRuntime.getProfilerController().getProfilerTime();
+    // ...some code you want to measure...
+    sGeckoRuntime.getProfilerController().addMarker("Marker Name", startTime);
+
+    // Duration marker with additional information
+    sGeckoRuntime.getProfilerController().addMarker("Marker Name", startTime, "info");
+
+There are various overloads of ``addMarker`` you can choose depending on your need.
+
+If you need to compute some information before adding it to a marker, it's
+recommended to wrap that code with a `isProfilerActive` if check to make sure
+that it's only executed while the profiler is active. Here's an example:
+
+.. code-block:: java
+
+  ProfilerController profilerController = runtime.getProfilerController();
+  if (profilerController.isProfilerActive()) {
+    // Compute the information you want to include.
+    String info = ...
+    sGeckoRuntime.getProfilerController().addMarker("Marker Name", info);
+  }
+
+Markers in the Fenix codebase
+*****************************
+
+If you are in the Fenix codebase, then you should have access to the Android
+components. The Android components includes a `Profiler interface here`_, with
+its corresponding `implementation here`_. You should be able to do everything
+you can do with the ``ProfilerController``. Here's an example on how to call them:
+
+.. code-block:: kotlin
+
+    // Simple marker
+    components.core.engine.profiler?.addMarker("Marker Name");
+
+    // Simple marker with additional information
+    components.core.engine.profiler?.addMarker("Marker Name", "info");
+
+    // Duration marker
+    val startTime = components.core.engine.profiler?.getProfilerTime()
+    // ...some code you want to measure...
+    components.core.engine.profiler?.addMarker("Marker Name", startTime, "additional info")
+
+    // Duration marker with additional information
+    components.core.engine.profiler?.addMarker("Marker Name", startTime, "info");
+
+Similarly, there are various overloads of ``addMarker`` you can choose depending on your needs.
+
+Like for the GeckoView example above, if you need to compute some information
+before adding it to a marker, it's recommended to wrap that code with a
+`isProfilerActive` if check to make sure that it's only executed while the
+profiler is active. Here's an example:
+
+.. code-block:: kotlin
+
+  if (components.core.engine.profiler?.isProfilerActive() == true) {
+    // Compute the information you want to include.
+    var info = ...
+    components.core.engine.profiler?.addMarker("Marker Name", info)
+  }
+
+.. _ProfilerController Java file: https://searchfox.org/mozilla-central/source/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/ProfilerController.java
+.. _javadoc: https://mozilla.github.io/geckoview/javadoc/mozilla-central/org/mozilla/geckoview/ProfilerController.html
+.. _Profiler interface here: https://searchfox.org/mozilla-central/source/mobile/android/android-components/components/concept/base/src/main/java/mozilla/components/concept/base/profiler/Profiler.kt
+.. _implementation here: https://searchfox.org/mozilla-central/source/mobile/android/android-components/components/browser/engine-gecko/src/main/java/mozilla/components/browser/engine/gecko/profiler/Profiler.kt
diff --git a/tools/profiler/docs/instrumenting-javascript.rst b/tools/profiler/docs/instrumenting-javascript.rst
index 928d94781e..4ad5118256 100644
--- a/tools/profiler/docs/instrumenting-javascript.rst
+++ b/tools/profiler/docs/instrumenting-javascript.rst
@@ -11,8 +11,9 @@ or record events that normally wouldn't show up in samples.
 
 .. note::
     This guide explains JavaScript markers in depth. To learn more about how to add a
-    marker in C++ or Rust, please take a look at their documentation
-    in :doc:`markers-guide` or :doc:`instrumenting-rust` respectively.
+    marker in C++, Rust or JVM please take a look at their documentation
+    in :doc:`markers-guide`, :doc:`instrumenting-rust` or :doc:`instrumenting-android`
+    respectively.
 
 Markers in Browser Chrome
 *************************
diff --git a/tools/profiler/docs/instrumenting-rust.rst b/tools/profiler/docs/instrumenting-rust.rst
index c3e12f42dc..603c008b6c 100644
--- a/tools/profiler/docs/instrumenting-rust.rst
+++ b/tools/profiler/docs/instrumenting-rust.rst
@@ -124,8 +124,9 @@ and an optional payload of a specific type (containing arbitrary data relevant t
 
 .. note::
     This guide explains Rust markers in depth. To learn more about how to add a
-    marker in C++ or JavaScript, please take a look at their documentation
-    in :doc:`markers-guide` or :doc:`instrumenting-javascript` respectively.
+    marker in C++, JavaScript or JVM, please take a look at their documentation
+    in :doc:`markers-guide` or :doc:`instrumenting-javascript`,
+    :doc:`instrumenting-android` respectively.
 
 Examples
 ^^^^^^^^
diff --git a/tools/profiler/docs/markers-guide.rst b/tools/profiler/docs/markers-guide.rst
index ed18b35867..ac0e4430b9 100644
--- a/tools/profiler/docs/markers-guide.rst
+++ b/tools/profiler/docs/markers-guide.rst
@@ -9,8 +9,9 @@ and an optional payload of a specific type (containing arbitrary data relevant t
 
 .. note::
     This guide explains C++ markers in depth. To learn more about how to add a
-    marker in JavaScript or Rust, please take a look at their documentation
-    in :doc:`instrumenting-javascript` or :doc:`instrumenting-rust` respectively.
+    marker in JavaScript, Rust or JVM, please take a look at their documentation
+    in :doc:`instrumenting-javascript`, :doc:`instrumenting-rust` or
+    :doc:`instrumenting-android` respectively.
 
 Example
 -------
diff --git a/tools/profiler/public/ProfilerControl.h b/tools/profiler/public/ProfilerControl.h
index ac145fac00..53fec681ce 100644
--- a/tools/profiler/public/ProfilerControl.h
+++ b/tools/profiler/public/ProfilerControl.h
@@ -61,6 +61,9 @@ static constexpr mozilla::PowerOfTwo32 PROFILER_DEFAULT_ENTRIES =
 static constexpr mozilla::PowerOfTwo32 PROFILER_DEFAULT_STARTUP_ENTRIES =
     mozilla::baseprofiler::BASE_PROFILER_DEFAULT_STARTUP_ENTRIES;
 
+static constexpr mozilla::PowerOfTwo32 PROFILER_DEFAULT_SIGHANDLE_ENTRIES =
+    mozilla::MakePowerOfTwo32<64 * 1024 * 1024>();  // 64M entries = 512MiB
+
 #  define PROFILER_DEFAULT_INTERVAL BASE_PROFILER_DEFAULT_INTERVAL
 #  define PROFILER_MAX_INTERVAL BASE_PROFILER_MAX_INTERVAL
 
diff --git a/tools/profiler/public/ProfilerCounts.h b/tools/profiler/public/ProfilerCounts.h
index cebca81e2c..bdd2ddef9a 100644
--- a/tools/profiler/public/ProfilerCounts.h
+++ b/tools/profiler/public/ProfilerCounts.h
@@ -20,6 +20,7 @@
 
 #  include "mozilla/Assertions.h"
 #  include "mozilla/Atomics.h"
+#  include "mozilla/DataMutex.h"
 
 class BaseProfilerCount;
 void profiler_add_sampled_counter(BaseProfilerCount* aCounter);
@@ -188,13 +189,33 @@ class ProfilerCounterTotal final : public BaseProfilerCount {
  public:
   ProfilerCounterTotal(const char* aLabel, const char* aCategory,
                        const char* aDescription)
-      : BaseProfilerCount(aLabel, &mCounter, &mNumber, aCategory,
-                          aDescription) {
+      : BaseProfilerCount(aLabel, &mCounter, &mNumber, aCategory, aDescription),
+        mRegistered(false, "ProfilerCounterTotal::mRegistered") {
     // Assume we're in libxul
+    Register();
+  }
+
+  virtual ~ProfilerCounterTotal() { Unregister(); }
+
+  void Register() {
+    auto registered = mRegistered.Lock();
+    if (*registered) {
+      return;
+    }
+
+    *registered = true;
     profiler_add_sampled_counter(this);
   }
 
-  virtual ~ProfilerCounterTotal() { profiler_remove_sampled_counter(this); }
+  void Unregister() {
+    auto registered = mRegistered.Lock();
+    if (!*registered) {
+      return;
+    }
+
+    *registered = false;
+    profiler_remove_sampled_counter(this);
+  }
 
   BaseProfilerCount& operator++() {
     Add(1);
@@ -208,6 +229,9 @@ class ProfilerCounterTotal final : public BaseProfilerCount {
 
   ProfilerAtomicSigned mCounter;
   ProfilerAtomicUnsigned mNumber;
+  // Using OffTheBooksMutex here because we intentionally leak memory counters
+  // if they are initialized.
+  mozilla::DataMutexBase<bool, mozilla::OffTheBooksMutex> mRegistered;
 };
 
 // Defines a counter that is sampled on each profiler tick, with a running
diff --git a/tools/profiler/public/ProfilerState.h b/tools/profiler/public/ProfilerState.h
index 40e1517c91..aad74862b3 100644
--- a/tools/profiler/public/ProfilerState.h
+++ b/tools/profiler/public/ProfilerState.h
@@ -118,7 +118,10 @@
         "every CPU core for every profiler sample.")                       \
                                                                            \
   MACRO(23, "bandwidth", Bandwidth,                                        \
-        "Record the network bandwidth used for every profiler sample.")
+        "Record the network bandwidth used for every profiler sample.")    \
+  MACRO(                                                                   \
+      24, "memory", Memory,                                                \
+      "Track the memory allocations and deallocations per process over time.")
 // *** Synchronize with lists in BaseProfilerState.h and geckoProfiler.json ***
 
 struct ProfilerFeature {
@@ -138,6 +141,12 @@ struct ProfilerFeature {
   PROFILER_FOR_EACH_FEATURE(DECLARE)
 
 #undef DECLARE
+
+  [[nodiscard]] static constexpr bool ShouldInstallMemoryHooks(
+      uint32_t aFeatures) {
+    return ProfilerFeature::HasMemory(aFeatures) ||
+           ProfilerFeature::HasNativeAllocations(aFeatures);
+  }
 };
 
 // clang-format off
diff --git a/tools/profiler/tests/gtest/moz.build b/tools/profiler/tests/gtest/moz.build
index e1c3994621..ea5ca1f228 100644
--- a/tools/profiler/tests/gtest/moz.build
+++ b/tools/profiler/tests/gtest/moz.build
@@ -30,7 +30,8 @@ LOCAL_INCLUDES += [
     "/tools/profiler/lul",
 ]
 
-if CONFIG["OS_TARGET"] != "Android":
+# Bug 1885381 - Hangs/timeouts under TSAN
+if CONFIG["OS_TARGET"] != "Android" and not CONFIG["MOZ_TSAN"]:
     UNIFIED_SOURCES += [
         "GeckoProfiler.cpp",
         "ThreadProfileTest.cpp",
diff --git a/tools/profiler/tests/xpcshell/test_feature_posix_signals.js b/tools/profiler/tests/xpcshell/test_feature_posix_signals.js
index 28fbf890e8..d4b77d6550 100644
--- a/tools/profiler/tests/xpcshell/test_feature_posix_signals.js
+++ b/tools/profiler/tests/xpcshell/test_feature_posix_signals.js
@@ -5,7 +5,7 @@
 ChromeUtils.defineESModuleGetters(this, {
   Downloads: "resource://gre/modules/Downloads.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  BrowserTestUtils: "resource://testing-common/BrowserTestUtils.sys.mjs",
+  TestUtils: "resource://testing-common/TestUtils.sys.mjs",
 });
 
 const { ctypes } = ChromeUtils.importESModule(
@@ -68,23 +68,6 @@ function raiseSignal(pid, sig) {
   return { ok: true };
 }
 
-// We would like to use the following to wait for a stop signal to actually be
-// handled:
-//  await Services.profiler.waitOnePeriodicSampling();
-// However, as we are trying to shut down the profiler using the sampler
-// thread, this can cause complications between the callback waiting for the
-// sampling to be over, and the sampler thread actually finishing.
-// Instead, we use the BrowserTestUtils.waitForCondition to wait until the
-// profiler is no longer active.
-async function waitUntilProfilerStopped(interval = 1000, maxTries = 100) {
-  await BrowserTestUtils.waitForCondition(
-    () => !Services.profiler.IsActive(),
-    "the profiler should be inactive",
-    interval,
-    maxTries
-  );
-}
-
 async function cleanupAfterTest() {
   // We need to cleanup written profiles after a test
   // Get the system downloads directory, and use it to build a profile file
@@ -112,10 +95,46 @@ async function cleanupAfterTest() {
 //  may cause a mismatch if we test on on, say, a gnu hurd kernel, or on a
 // linux kernel running on sparc, but the feature will not break - only
 // the testing.
-// const SIGUSR1 = Services.appinfo.OS === "Darwin" ? 30 : 10;
+const SIGUSR1 = Services.appinfo.OS === "Darwin" ? 30 : 10;
 const SIGUSR2 = Services.appinfo.OS === "Darwin" ? 31 : 12;
 
 add_task(async () => {
+  info("Test that starting the profiler with a posix signal works.");
+
+  Assert.ok(
+    !Services.profiler.IsActive(),
+    "The profiler should not begin the test active."
+  );
+
+  // Get the process ID
+  let pid = Services.appinfo.processID;
+
+  // Set up an observer to watch for the profiler starting
+  let startPromise = TestUtils.topicObserved("profiler-started");
+
+  // Try and start the profiler using a signal.
+  let result = raiseSignal(pid, SIGUSR1);
+  Assert.ok(result, "Raising a signal should succeed");
+
+  // Wait for the profiler to stop
+  Assert.ok(await startPromise, "The profiler should start");
+
+  // Wait until the profiler is active
+  Assert.ok(Services.profiler.IsActive(), "The profiler should now be active.");
+
+  // Let the profiler sample at least once
+  await Services.profiler.waitOnePeriodicSampling();
+  info("Waiting a periodic sampling completed");
+
+  // Stop the profiler
+  await Services.profiler.StopProfiler();
+  Assert.ok(
+    !Services.profiler.IsActive(),
+    "The profiler should now be inactive."
+  );
+});
+
+add_task(async () => {
   info("Test that stopping the profiler with a posix signal works.");
   registerCleanupFunction(cleanupAfterTest);
 
@@ -136,13 +155,20 @@ add_task(async () => {
   // Get the process ID
   let pid = Services.appinfo.processID;
 
+  // Set up an observer to watch for the profiler stopping
+  let stopPromise = TestUtils.topicObserved("profiler-stopped");
+
   // Try and stop the profiler using a signal.
   let result = raiseSignal(pid, SIGUSR2);
   Assert.ok(result, "Raising a SIGUSR2 signal should succeed.");
 
-  await waitUntilProfilerStopped();
+  // Wait for the profiler to stop
+  Assert.ok(await stopPromise, "The profiler should stop");
 
-  do_test_finished();
+  Assert.ok(
+    !Services.profiler.IsActive(),
+    "The profiler should now be inactive."
+  );
 });
 
 add_task(async () => {
@@ -174,21 +200,24 @@ add_task(async () => {
   await Services.profiler.StartProfiler(entries, interval, threads, features);
   Assert.ok(Services.profiler.IsActive(), "The profiler should now be active.");
 
+  // Set up an observer to watch for the profiler stopping
+  let stopPromise = TestUtils.topicObserved("profiler-stopped");
+
   // Try and stop the profiler using a signal.
   let result = raiseSignal(pid, SIGUSR2);
   Assert.ok(result, "Raising a SIGUSR2 signal should succeed.");
 
-  // Wait for the file to exist
-  await BrowserTestUtils.waitForCondition(
-    async () => await IOUtils.exists(profile.path),
-    "Waiting for a profile file to be written to disk."
+  // Wait for the profiler to stop
+  Assert.ok(await stopPromise, "The profiler should stop");
+
+  // Now that it's stopped, make sure that we have a profile file
+  Assert.ok(
+    await IOUtils.exists(profile.path),
+    "A profile file should be written to disk."
   );
 
-  await waitUntilProfilerStopped();
   Assert.ok(
     !Services.profiler.IsActive(),
     "The profiler should now be inactive."
   );
-
-  do_test_finished();
 });
diff --git a/tools/profiler/tests/xpcshell/xpcshell.toml b/tools/profiler/tests/xpcshell/xpcshell.toml
index 2cde39d09f..8e58e1ff08 100644
--- a/tools/profiler/tests/xpcshell/xpcshell.toml
+++ b/tools/profiler/tests/xpcshell/xpcshell.toml
@@ -49,8 +49,10 @@ skip-if = [
 
 ["test_feature_posix_signals.js"]
 skip-if = [
-  "ccov",
-  "os == 'win'",
+  "tsan", # We have intermittent timeout issues in TSan, see Bug 1889828
+  "ccov", # The signals for the profiler conflict with the ccov signals
+  "os == 'win'", # Not yet supported on windows
+  "os == 'android'", # Not yet supported on android
 ]
 
 # Native stackwalking is somewhat unreliable depending on the platform.