Merging upstream version 126.0.

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

15 files changed, 746 insertions, 108 deletions

diff --git a/tools/profiler/core/MicroGeckoProfiler.cpp b/tools/profiler/core/MicroGeckoProfiler.cpp
index bedb755742..6c384aeb41 100644
--- a/tools/profiler/core/MicroGeckoProfiler.cpp
+++ b/tools/profiler/core/MicroGeckoProfiler.cpp
@@ -133,10 +133,10 @@ struct ProfileBufferEntryReader::Deserializer<TraceOption> {
 }  // namespace mozilla
 #endif  // MOZ_GECKO_PROFILER
 
-void uprofiler_simple_event_marker(const char* name, char phase, int num_args,
-                                   const char** arg_names,
-                                   const unsigned char* arg_types,
-                                   const unsigned long long* arg_values) {
+void uprofiler_simple_event_marker_internal(
+    const char* name, char phase, int num_args, const char** arg_names,
+    const unsigned char* arg_types, const unsigned long long* arg_values,
+    bool full_stack) {
 #ifdef MOZ_GECKO_PROFILER
   if (!profiler_thread_is_being_profiled_for_markers()) {
     return;
@@ -196,8 +196,27 @@ void uprofiler_simple_event_marker(const char* name, char phase, int num_args,
         break;
     }
   }
-  profiler_add_marker(ProfilerString8View::WrapNullTerminatedString(name),
-                      geckoprofiler::category::MEDIA_RT, {timing.extract()},
-                      TraceMarker{}, tuple);
+  profiler_add_marker(
+      ProfilerString8View::WrapNullTerminatedString(name),
+      geckoprofiler::category::MEDIA_RT,
+      {timing.extract(),
+       full_stack ? MarkerStack::Capture(StackCaptureOptions::Full)
+                  : MarkerStack::Capture(StackCaptureOptions::NoStack)},
+      TraceMarker{}, tuple);
 #endif  // MOZ_GECKO_PROFILER
 }
+
+void uprofiler_simple_event_marker_with_stack(
+    const char* name, char phase, int num_args, const char** arg_names,
+    const unsigned char* arg_types, const unsigned long long* arg_values) {
+  uprofiler_simple_event_marker_internal(name, phase, num_args, arg_names,
+                                         arg_types, arg_values, true);
+}
+
+void uprofiler_simple_event_marker(const char* name, char phase, int num_args,
+                                   const char** arg_names,
+                                   const unsigned char* arg_types,
+                                   const unsigned long long* arg_values) {
+  uprofiler_simple_event_marker_internal(name, phase, num_args, arg_names,
+                                         arg_types, arg_values, false);
+}
diff --git a/tools/profiler/core/PowerCounters-android.cpp b/tools/profiler/core/PowerCounters-android.cpp
new file mode 100644
index 0000000000..5e784952b5
--- /dev/null
+++ b/tools/profiler/core/PowerCounters-android.cpp
@@ -0,0 +1,178 @@
+/* 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 "PowerCounters.h"
+#include "nsXULAppAPI.h"  // for XRE_IsParentProcess
+#include <dlfcn.h>
+
+#define ALOG(args...) \
+  __android_log_print(ANDROID_LOG_INFO, "GeckoProfiler", ##args)
+
+/*
+ * The following declarations come from the dlext.h header (not in the ndk).
+ * https://cs.android.com/android/platform/superproject/main/+/main:bionic/libc/include/android/dlext.h;drc=655e430b28d7404f763e7ebefe84fba5a387666d
+ */
+struct android_namespace_t;
+typedef struct {
+  /** A bitmask of `ANDROID_DLEXT_` enum values. */
+  uint64_t flags;
+
+  /** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and
+   * `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
+  void* _Nullable reserved_addr;
+  /** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and
+   * `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
+  size_t reserved_size;
+
+  /** Used by `ANDROID_DLEXT_WRITE_RELRO` and `ANDROID_DLEXT_USE_RELRO`. */
+  int relro_fd;
+
+  /** Used by `ANDROID_DLEXT_USE_LIBRARY_FD`. */
+  int library_fd;
+  /** Used by `ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET` */
+  off64_t library_fd_offset;
+
+  /** Used by `ANDROID_DLEXT_USE_NAMESPACE`. */
+  struct android_namespace_t* _Nullable library_namespace;
+} android_dlextinfo;
+enum { ANDROID_DLEXT_USE_NAMESPACE = 0x200 };
+extern "C"
+    __attribute__((visibility("default"))) void* _Nullable android_dlopen_ext(
+        const char* _Nullable __filename, int __flags,
+        const android_dlextinfo* _Nullable __info);
+
+// See also documentation at
+// https://developer.android.com/studio/profile/power-profiler#power-rails
+bool GetAvailableRails(RailDescriptor*, size_t* size_of_arr);
+
+class RailEnergy final : public BaseProfilerCount {
+ public:
+  explicit RailEnergy(RailEnergyData* data, const char* aRailName,
+                      const char* aSubsystemName)
+      : BaseProfilerCount(aSubsystemName, nullptr, nullptr, "power", aRailName),
+        mDataPtr(data),
+        mLastTimestamp(0) {}
+
+  ~RailEnergy() {}
+
+  RailEnergy(const RailEnergy&) = delete;
+  RailEnergy& operator=(const RailEnergy&) = delete;
+
+  CountSample Sample() override {
+    CountSample result = {
+        // RailEnergyData.energy is in microwatt-seconds (uWs)
+        // we need to return values in picowatt-hour.
+        .count = static_cast<int64_t>(mDataPtr->energy * 1e3 / 3.6),
+        .number = 0,
+        .isSampleNew = mDataPtr->timestamp != mLastTimestamp,
+    };
+    mLastTimestamp = mDataPtr->timestamp;
+    return result;
+  }
+
+ private:
+  RailEnergyData* mDataPtr;
+  uint64_t mLastTimestamp;
+};
+
+PowerCounters::PowerCounters() {
+  if (!XRE_IsParentProcess()) {
+    // Energy meters are global, so only sample them on the parent.
+    return;
+  }
+
+  // A direct dlopen call on libperfetto_android_internal.so fails with a
+  // namespace error because libperfetto_android_internal.so is missing in
+  // /etc/public.libraries.txt
+  // Instead, use android_dlopen_ext with the "default" namespace.
+  void* libcHandle = dlopen("libc.so", RTLD_LAZY);
+  if (!libcHandle) {
+    ALOG("failed to dlopen libc: %s", dlerror());
+    return;
+  }
+
+  struct android_namespace_t* (*android_get_exported_namespace)(const char*) =
+      reinterpret_cast<struct android_namespace_t* (*)(const char*)>(
+          dlsym(libcHandle, "__loader_android_get_exported_namespace"));
+  if (!android_get_exported_namespace) {
+    ALOG("failed to get __loader_android_get_exported_namespace: %s",
+         dlerror());
+    return;
+  }
+
+  struct android_namespace_t* ns = android_get_exported_namespace("default");
+  const android_dlextinfo dlextinfo = {
+      .flags = ANDROID_DLEXT_USE_NAMESPACE,
+      .library_namespace = ns,
+  };
+
+  mLibperfettoModule = android_dlopen_ext("libperfetto_android_internal.so",
+                                          RTLD_LOCAL | RTLD_LAZY, &dlextinfo);
+  MOZ_ASSERT(mLibperfettoModule);
+  if (!mLibperfettoModule) {
+    ALOG("failed to get libperfetto handle: %s", dlerror());
+    return;
+  }
+
+  decltype(&GetAvailableRails) getAvailableRails =
+      reinterpret_cast<decltype(&GetAvailableRails)>(
+          dlsym(mLibperfettoModule, "GetAvailableRails"));
+  if (!getAvailableRails) {
+    ALOG("failed to get GetAvailableRails pointer: %s", dlerror());
+    return;
+  }
+
+  constexpr size_t kMaxNumRails = 32;
+  if (!mRailDescriptors.resize(kMaxNumRails)) {
+    ALOG("failed to grow mRailDescriptors");
+    return;
+  }
+  size_t numRails = mRailDescriptors.length();
+  getAvailableRails(&mRailDescriptors[0], &numRails);
+  mRailDescriptors.shrinkTo(numRails);
+  ALOG("found %zu rails", numRails);
+  if (numRails == 0) {
+    // We will see 0 rails either if the device has no support for power
+    // profiling or if the SELinux policy blocks access (ie. on a non-rooted
+    // device).
+    return;
+  }
+
+  if (!mRailEnergyData.resize(numRails)) {
+    ALOG("failed to grow mRailEnergyData");
+    return;
+  }
+  for (size_t i = 0; i < numRails; ++i) {
+    RailDescriptor& rail = mRailDescriptors[i];
+    ALOG("rail %zu, name: %s, subsystem: %s", i, rail.rail_name,
+         rail.subsys_name);
+    RailEnergy* railEnergy =
+        new RailEnergy(&mRailEnergyData[i], rail.rail_name, rail.subsys_name);
+    if (!mCounters.emplaceBack(railEnergy)) {
+      delete railEnergy;
+    }
+  }
+
+  mGetRailEnergyData = reinterpret_cast<decltype(&GetRailEnergyData)>(
+      dlsym(mLibperfettoModule, "GetRailEnergyData"));
+  if (!mGetRailEnergyData) {
+    ALOG("failed to get GetRailEnergyData pointer");
+    return;
+  }
+}
+PowerCounters::~PowerCounters() {
+  if (mLibperfettoModule) {
+    dlclose(mLibperfettoModule);
+  }
+}
+void PowerCounters::Sample() {
+  // Energy meters are global, so only sample them on the parent.
+  // Also return early if we failed to access the GetRailEnergyData symbol.
+  if (!XRE_IsParentProcess() || !mGetRailEnergyData) {
+    return;
+  }
+
+  size_t length = mRailEnergyData.length();
+  mGetRailEnergyData(&mRailEnergyData[0], &length);
+}
diff --git a/tools/profiler/core/PowerCounters-linux.cpp b/tools/profiler/core/PowerCounters-linux.cpp
index 006cea4867..a28171a6e2 100644
--- a/tools/profiler/core/PowerCounters-linux.cpp
+++ b/tools/profiler/core/PowerCounters-linux.cpp
@@ -276,12 +276,3 @@ PowerCounters::PowerCounters() {
     }
   }
 }
-
-PowerCounters::~PowerCounters() {
-  for (auto* raplEvent : mCounters) {
-    delete raplEvent;
-  }
-  mCounters.clear();
-}
-
-void PowerCounters::Sample() {}
diff --git a/tools/profiler/core/PowerCounters-mac-amd64.cpp b/tools/profiler/core/PowerCounters-mac-amd64.cpp
index 540cee155d..c5a82694cd 100644
--- a/tools/profiler/core/PowerCounters-mac-amd64.cpp
+++ b/tools/profiler/core/PowerCounters-mac-amd64.cpp
@@ -350,13 +350,7 @@ class RAPL {
     }
   }
 
-  ~RAPL() {
-    free(mPkes);
-    delete mPkg;
-    delete mCores;
-    delete mGpu;
-    delete mRam;
-  }
+  ~RAPL() { free(mPkes); }
 
   void Sample() {
     constexpr uint64_t kSupportedVersion = 1;
@@ -403,14 +397,14 @@ class RAPL {
 
 PowerCounters::PowerCounters() {
   // RAPL values are global, so only sample them on the parent.
-  mRapl = XRE_IsParentProcess() ? new RAPL(mCounters) : nullptr;
+  if (XRE_IsParentProcess()) {
+    mRapl = mozilla::MakeUnique<RAPL>(mCounters);
+  }
 }
 
-PowerCounters::~PowerCounters() {
-  mCounters.clear();
-  delete mRapl;
-  mRapl = nullptr;
-}
+// This default destructor can not be defined in the header file as it depends
+// on the full definition of RAPL which lives in this file.
+PowerCounters::~PowerCounters() {}
 
 void PowerCounters::Sample() {
   if (mRapl) {
diff --git a/tools/profiler/core/PowerCounters-mac-arm64.cpp b/tools/profiler/core/PowerCounters-mac-arm64.cpp
index 3a84a479ef..76fceeca8d 100644
--- a/tools/profiler/core/PowerCounters-mac-arm64.cpp
+++ b/tools/profiler/core/PowerCounters-mac-arm64.cpp
@@ -36,12 +36,4 @@ class ProcessPower final : public BaseProfilerCount {
   }
 };
 
-PowerCounters::PowerCounters() : mProcessPower(new ProcessPower()) {
-  if (mProcessPower) {
-    (void)mCounters.append(mProcessPower.get());
-  }
-}
-
-PowerCounters::~PowerCounters() { mCounters.clear(); }
-
-void PowerCounters::Sample() {}
+PowerCounters::PowerCounters() { (void)mCounters.append(new ProcessPower()); }
diff --git a/tools/profiler/core/PowerCounters-win.cpp b/tools/profiler/core/PowerCounters-win.cpp
index 6e8f492d6d..535a553867 100644
--- a/tools/profiler/core/PowerCounters-win.cpp
+++ b/tools/profiler/core/PowerCounters-win.cpp
@@ -212,13 +212,13 @@ class PowerMeterDevice {
   void AppendCountersTo(PowerCounters::CountVector& aCounters) {
     if (aCounters.reserve(aCounters.length() + mChannels.length())) {
       for (auto& channel : mChannels) {
-        aCounters.infallibleAppend(channel.get());
+        aCounters.infallibleAppend(channel);
       }
     }
   }
 
  private:
-  Vector<UniquePtr<PowerMeterChannel>, 4> mChannels;
+  Vector<PowerMeterChannel*, 4> mChannels;
   HANDLE mHandle = INVALID_HANDLE_VALUE;
   UniquePtr<EMI_CHANNEL_MEASUREMENT_DATA[]> mDataBuffer;
 };
@@ -301,7 +301,9 @@ PowerCounters::PowerCounters() {
   }
 }
 
-PowerCounters::~PowerCounters() { mCounters.clear(); }
+// This default destructor can not be defined in the header file as it depends
+// on the full definition of PowerMeterDevice which lives in this file.
+PowerCounters::~PowerCounters() {}
 
 void PowerCounters::Sample() {
   for (auto& device : mPowerMeterDevices) {
diff --git a/tools/profiler/core/PowerCounters.h b/tools/profiler/core/PowerCounters.h
index 2fd8d5892c..df511e87ec 100644
--- a/tools/profiler/core/PowerCounters.h
+++ b/tools/profiler/core/PowerCounters.h
@@ -19,20 +19,57 @@ class ProcessPower;
 #if defined(GP_PLAT_amd64_darwin)
 class RAPL;
 #endif
+#if defined(GP_PLAT_arm64_android)
+
+/*
+ * These declarations come from:
+ * https://cs.android.com/android/platform/superproject/main/+/main:external/perfetto/src/android_internal/power_stats.h;l=34-52;drc=1777bdef274bcfbccd4e6f8b6d00a1bac48a8645
+ */
+
+struct RailDescriptor {
+  // Index corresponding to the rail
+  uint32_t index;
+  // Name of the rail
+  char rail_name[64];
+  // Name of the subsystem to which this rail belongs
+  char subsys_name[64];
+  // Hardware sampling rate
+  uint32_t sampling_rate;
+};
+
+struct RailEnergyData {
+  // Index corresponding to RailDescriptor.index
+  uint32_t index;
+  // Time since device boot(CLOCK_BOOTTIME) in milli-seconds
+  uint64_t timestamp;
+  // Accumulated energy since device boot in microwatt-seconds (uWs)
+  uint64_t energy;
+};
+bool GetRailEnergyData(RailEnergyData*, size_t* size_of_arr);
+#endif
 
 class PowerCounters {
  public:
-#if defined(_MSC_VER) || defined(GP_OS_darwin) || defined(GP_PLAT_amd64_linux)
+#if defined(_MSC_VER) || defined(GP_OS_darwin) || \
+    defined(GP_PLAT_amd64_linux) || defined(GP_PLAT_arm64_android)
   explicit PowerCounters();
+#else
+  explicit PowerCounters(){};
+#endif
+#if defined(_MSC_VER) || defined(GP_PLAT_amd64_darwin) || \
+    defined(GP_PLAT_arm64_android)
   ~PowerCounters();
+#else
+  ~PowerCounters() = default;
+#endif
+#if defined(_MSC_VER) || defined(GP_PLAT_amd64_darwin) || \
+    defined(GP_PLAT_arm64_android)
   void Sample();
 #else
-  explicit PowerCounters(){};
-  ~PowerCounters(){};
   void Sample(){};
 #endif
 
-  using CountVector = mozilla::Vector<BaseProfilerCount*, 4>;
+  using CountVector = mozilla::Vector<mozilla::UniquePtr<BaseProfilerCount>, 4>;
   const CountVector& GetCounters() { return mCounters; }
 
  private:
@@ -41,11 +78,14 @@ class PowerCounters {
 #if defined(_MSC_VER)
   mozilla::Vector<mozilla::UniquePtr<PowerMeterDevice>> mPowerMeterDevices;
 #endif
-#if defined(GP_PLAT_arm64_darwin)
-  mozilla::UniquePtr<ProcessPower> mProcessPower;
-#endif
 #if defined(GP_PLAT_amd64_darwin)
-  RAPL* mRapl;
+  mozilla::UniquePtr<RAPL> mRapl;
+#endif
+#if defined(GP_PLAT_arm64_android)
+  void* mLibperfettoModule = nullptr;
+  decltype(&GetRailEnergyData) mGetRailEnergyData = nullptr;
+  mozilla::Vector<RailDescriptor> mRailDescriptors;
+  mozilla::Vector<RailEnergyData> mRailEnergyData;
 #endif
 };
 
diff --git a/tools/profiler/core/platform-linux-android.cpp b/tools/profiler/core/platform-linux-android.cpp
index 11af93456c..8e93ca4e91 100644
--- a/tools/profiler/core/platform-linux-android.cpp
+++ b/tools/profiler/core/platform-linux-android.cpp
@@ -551,7 +551,11 @@ SamplerThread::SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
 }
 
 SamplerThread::~SamplerThread() {
-  pthread_join(mThread, nullptr);
+  if (pthread_equal(mThread, pthread_self())) {
+    pthread_detach(mThread);
+  } else {
+    pthread_join(mThread, nullptr);
+  }
   // Just in the unlikely case some callbacks were added between the end of the
   // thread and now.
   InvokePostSamplingCallbacks(std::move(mPostSamplingCallbackList),
diff --git a/tools/profiler/core/platform-macos.cpp b/tools/profiler/core/platform-macos.cpp
index 78f000c470..ad0b0699f3 100644
--- a/tools/profiler/core/platform-macos.cpp
+++ b/tools/profiler/core/platform-macos.cpp
@@ -256,7 +256,11 @@ SamplerThread::SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
 }
 
 SamplerThread::~SamplerThread() {
-  pthread_join(mThread, nullptr);
+  if (pthread_equal(mThread, pthread_self())) {
+    pthread_detach(mThread);
+  } else {
+    pthread_join(mThread, nullptr);
+  }
   // Just in the unlikely case some callbacks were added between the end of the
   // thread and now.
   InvokePostSamplingCallbacks(std::move(mPostSamplingCallbackList),
diff --git a/tools/profiler/core/platform.cpp b/tools/profiler/core/platform.cpp
index 8ce029402b..6b7e318f80 100644
--- a/tools/profiler/core/platform.cpp
+++ b/tools/profiler/core/platform.cpp
@@ -42,7 +42,12 @@
 #include "ProfilerIOInterposeObserver.h"
 #include "ProfilerParent.h"
 #include "ProfilerRustBindings.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Maybe.h"
 #include "mozilla/MozPromise.h"
+#include "nsCOMPtr.h"
+#include "nsDebug.h"
+#include "nsXPCOM.h"
 #include "shared-libraries.h"
 #include "VTuneProfiler.h"
 #include "ETWTools.h"
@@ -95,6 +100,7 @@
 #include "nsSystemInfo.h"
 #include "nsThreadUtils.h"
 #include "nsXULAppAPI.h"
+#include "nsDirectoryServiceUtils.h"
 #include "Tracing.h"
 #include "prdtoa.h"
 #include "prtime.h"
@@ -108,6 +114,18 @@
 #include <string_view>
 #include <type_traits>
 
+// 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.
+#ifndef MOZ_CODE_COVERAGE
+#  ifdef XP_WIN
+// TODO: Add support for windows "signal"-like behaviour. See Bug 1867328.
+#  else
+#    include <signal.h>
+#    include <unistd.h>
+#  endif
+#endif
+
 #if defined(GP_OS_android)
 #  include "JavaExceptions.h"
 #  include "mozilla/java/GeckoJavaSamplerNatives.h"
@@ -234,6 +252,10 @@ ProfileChunkedBuffer& profiler_get_core_buffer() {
 
 mozilla::Atomic<int, mozilla::MemoryOrdering::Relaxed> gSkipSampling;
 
+// Atomic flag to stop the profiler from within the sampling loop
+mozilla::Atomic<bool, mozilla::MemoryOrdering::Relaxed> gStopAndDumpFromSignal(
+    false);
+
 #if defined(GP_OS_android)
 class GeckoJavaSampler
     : public java::GeckoJavaSampler::Natives<GeckoJavaSampler> {
@@ -647,6 +669,9 @@ class CorePS {
 
   PS_GET_AND_SET(const nsACString&, ProcessName)
   PS_GET_AND_SET(const nsACString&, ETLDplus1)
+#if !defined(XP_WIN)
+  PS_GET_AND_SET(const Maybe<nsCOMPtr<nsIFile>>&, DownloadDirectory)
+#endif
 
   static void SetBandwidthCounter(ProfilerBandwidthCounter* aBandwidthCounter) {
     MOZ_ASSERT(sInstance);
@@ -695,6 +720,11 @@ class CorePS {
   // lock, so it is safe to have only one instance allocated for all of the
   // threads.
   JsFrameBuffer mJsFrames;
+
+  // Cached download directory for when we need to dump profiles to disk.
+#if !defined(XP_WIN)
+  Maybe<nsCOMPtr<nsIFile>> mDownloadDirectory;
+#endif
 };
 
 CorePS* CorePS::sInstance = nullptr;
@@ -839,7 +869,7 @@ class ActivePS {
     if (ProfilerFeature::HasPower(aFeatures)) {
       mMaybePowerCounters = new PowerCounters();
       for (const auto& powerCounter : mMaybePowerCounters->GetCounters()) {
-        locked_profiler_add_sampled_counter(aLock, powerCounter);
+        locked_profiler_add_sampled_counter(aLock, powerCounter.get());
       }
     }
 
@@ -935,7 +965,7 @@ class ActivePS {
     if (sInstance->mMaybePowerCounters) {
       for (const auto& powerCounter :
            sInstance->mMaybePowerCounters->GetCounters()) {
-        locked_profiler_remove_sampled_counter(aLock, powerCounter);
+        locked_profiler_remove_sampled_counter(aLock, powerCounter.get());
       }
       delete sInstance->mMaybePowerCounters;
       sInstance->mMaybePowerCounters = nullptr;
@@ -1918,11 +1948,10 @@ static uint32_t ExtractJsFrames(
 // Merges the profiling stack, native stack, and JS stack, outputting the
 // details to aCollector.
 static void MergeStacks(
-    uint32_t aFeatures, bool aIsSynchronous,
+    bool aIsSynchronous,
     const ThreadRegistration::UnlockedReaderAndAtomicRWOnThread& aThreadData,
-    const Registers& aRegs, const NativeStack& aNativeStack,
-    ProfilerStackCollector& aCollector, JsFrame* aJsFrames,
-    uint32_t aJsFramesCount) {
+    const NativeStack& aNativeStack, ProfilerStackCollector& aCollector,
+    JsFrame* aJsFrames, uint32_t aJsFramesCount) {
   // WARNING: this function runs within the profiler's "critical section".
   // WARNING: this function might be called while the profiler is inactive, and
   //          cannot rely on ActivePS.
@@ -2571,13 +2600,13 @@ static inline void DoSharedSample(
     DoNativeBacktrace(aThreadData, aRegs, nativeStack,
                       stackWalkControlIfSupported);
 
-    MergeStacks(aFeatures, aIsSynchronous, aThreadData, aRegs, nativeStack,
-                collector, aJsFrames, jsFramesCount);
+    MergeStacks(aIsSynchronous, aThreadData, nativeStack, collector, aJsFrames,
+                jsFramesCount);
   } else
 #endif
   {
-    MergeStacks(aFeatures, aIsSynchronous, aThreadData, aRegs, nativeStack,
-                collector, aJsFrames, jsFramesCount);
+    MergeStacks(aIsSynchronous, aThreadData, nativeStack, collector, aJsFrames,
+                jsFramesCount);
 
     // We can't walk the whole native stack, but we can record the top frame.
     if (aCaptureOptions == StackCaptureOptions::Full) {
@@ -2933,16 +2962,6 @@ static void StreamMetaJSCustomObject(
   ActivePS::WriteActiveConfiguration(aLock, aWriter,
                                      MakeStringSpan("configuration"));
 
-  if (!NS_IsMainThread()) {
-    // Leave the rest of the properties out if we're not on the main thread.
-    // At the moment, the only case in which this function is called on a
-    // background thread is if we're in a content process and are going to
-    // send this profile to the parent process. In that case, the parent
-    // process profile's "meta" object already has the rest of the properties,
-    // and the parent process profile is dumped on that process's main thread.
-    return;
-  }
-
   aWriter.DoubleProperty("interval", ActivePS::Interval(aLock));
   aWriter.IntProperty("stackwalk", ActivePS::FeatureStackWalk(aLock));
 
@@ -3019,6 +3038,16 @@ static void StreamMetaJSCustomObject(
   }
   aWriter.EndObject();
 
+  if (!NS_IsMainThread()) {
+    // Leave the rest of the properties out if we're not on the main thread.
+    // At the moment, the only case in which this function is called on a
+    // background thread is if we're in a content process and are going to
+    // send this profile to the parent process. In that case, the parent
+    // process profile's "meta" object already has the rest of the properties,
+    // and the parent process profile is dumped on that process's main thread.
+    return;
+  }
+
   // We should avoid collecting extension metadata for profiler when there is no
   // observer service, since a ExtensionPolicyService could not be created then.
   if (nsCOMPtr<nsIObserverService> os = services::GetObserverService()) {
@@ -4077,6 +4106,10 @@ 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() {
@@ -4732,6 +4765,27 @@ 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.
@@ -4840,10 +4894,10 @@ void SamplerThread::SpyOnUnregisteredThreads() {
       /* aWindowInfo = */ nsTArray<WindowInfo>{},
       /* aUtilityInfo = */ nsTArray<UtilityInfo>{},
       /* aChild = */ 0
-#ifdef XP_MACOSX
+#ifdef XP_DARWIN
       ,
       /* aChildTask = */ MACH_PORT_NULL
-#endif  // XP_MACOSX
+#endif  // XP_DARWIN
   );
 
   const ProcInfoPromise::ResolveOrRejectValue procInfoOrError =
@@ -5240,6 +5294,104 @@ static const char* get_size_suffix(const char* str) {
   return ptr;
 }
 
+#if !defined(XP_WIN) && !defined(MOZ_CODE_COVERAGE)
+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;
+}
+#endif
+
+// This may fail if we have previously had an issue finding the download
+// directory, or if the directory has moved since we cached the path.
+// This is non-ideal, but captured by Bug 1885000
+Maybe<nsAutoCString> profiler_find_dump_path() {
+// Note, this is currently a posix-only implementation, as we currently have
+// issues with fetching the download directory on Windows. See Bug 1890154.
+#if defined(XP_WIN)
+  return Nothing();
+#else
+  Maybe<nsCOMPtr<nsIFile>> directory = Nothing();
+  nsAutoCString path;
+
+  {
+    // Acquire the lock so that we can get things from CorePS
+    PSAutoLock lock;
+    Maybe<nsCOMPtr<nsIFile>> downloadDir = Nothing();
+    downloadDir = CorePS::DownloadDirectory(lock);
+
+    // This needs to be done within the context of the lock, as otherwise
+    // another thread might modify CorePS::mDownloadDirectory while we're
+    // cloning the pointer.
+    if (downloadDir) {
+      nsCOMPtr<nsIFile> d;
+      downloadDir.value()->Clone(getter_AddRefs(d));
+      directory = Some(d);
+    } else {
+      return Nothing();
+    }
+  }
+
+  // Now, we can check to see if we have a directory, and use it to construct
+  // the output file
+  if (directory) {
+    // Set up the name of our profile file
+    path.AppendPrintf("profile_%i_%i.json", XRE_GetProcessType(), getpid());
+
+    // Append it to the directory we found
+    nsresult rv = directory.value()->AppendNative(path);
+    if (NS_FAILED(rv)) {
+      LOG("Failed to append path to profile file");
+      return Nothing();
+    }
+
+    // Write the result *back* to the original path
+    rv = directory.value()->GetNativePath(path);
+    if (NS_FAILED(rv)) {
+      LOG("Failed to get native path for temp path");
+      return Nothing();
+    }
+
+    return Some(path);
+  }
+
+  return Nothing();
+#endif
+}
+
+void profiler_dump_and_stop() {
+  // pause the profiler until we are done dumping
+  profiler_pause();
+
+  // Try to save the profile to a file
+  if (auto path = profiler_find_dump_path()) {
+    profiler_save_profile_to_file(path.value().get());
+  } else {
+    LOG("Failed to dump profile to disk");
+  }
+
+  // Stop the profiler
+  profiler_stop();
+}
+
+void profiler_init_signal_handlers() {
+#if !defined(XP_WIN) && !defined(MOZ_CODE_COVERAGE)
+  // Set a handler to stop the profiler
+  struct sigaction prof_stop_sa {};
+  memset(&prof_stop_sa, 0, sizeof(struct sigaction));
+  prof_stop_sa.sa_sigaction = profiler_stop_signal_handler;
+  prof_stop_sa.sa_flags = SA_RESTART | SA_SIGINFO;
+  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
+}
+
 void profiler_init(void* aStackTop) {
   LOG("profiler_init");
 
@@ -5289,10 +5441,12 @@ void profiler_init(void* aStackTop) {
         locked_register_thread(lock, offThreadRef);
       }
     }
-
     // Platform-specific initialization.
     PlatformInit(lock);
 
+    // Initialise the signal handlers needed to start/stop the profiler
+    profiler_init_signal_handlers();
+
 #if defined(GP_OS_android)
     if (jni::IsAvailable()) {
       GeckoJavaSampler::Init();
@@ -6309,6 +6463,37 @@ bool profiler_is_paused() {
   return ActivePS::AppendPostSamplingCallback(lock, std::move(aCallback));
 }
 
+// See `ProfilerControl.h` for more details.
+void profiler_lookup_download_directory() {
+// This implementation is causing issues on Windows (see Bug 1890154) but as it
+// only exists to support the posix signal handling (on non-windows platforms)
+// we can remove it for now.
+#if !defined(XP_WIN)
+  LOG("profiler_lookup_download_directory");
+
+  MOZ_ASSERT(
+      NS_IsMainThread(),
+      "We can only get access to the directory service from the main thread");
+
+  // Make sure the profiler is actually running~
+  MOZ_RELEASE_ASSERT(CorePS::Exists());
+
+  // take the lock so that we can write to CorePS
+  PSAutoLock lock;
+
+  nsCOMPtr<nsIFile> tDownloadDir;
+  nsresult rv = NS_GetSpecialDirectory(NS_OS_DEFAULT_DOWNLOAD_DIR,
+                                       getter_AddRefs(tDownloadDir));
+  if (NS_FAILED(rv)) {
+    LOG("Failed to find download directory. Profiler signal handling will not "
+        "be able to save to disk. Error: %s",
+        GetStaticErrorName(rv));
+  } else {
+    CorePS::SetDownloadDirectory(lock, Some(tDownloadDir));
+  }
+#endif
+}
+
 RefPtr<GenericPromise> profiler_pause() {
   LOG("profiler_pause");
 
@@ -7157,13 +7342,13 @@ static void profiler_suspend_and_sample_thread(
 #    error "Invalid configuration"
 #  endif
 
-      MergeStacks(aFeatures, !aLockIfAsynchronousSampling, aThreadData, aRegs,
-                  nativeStack, aCollector, aJsFrames, jsFramesCount);
+      MergeStacks(!aLockIfAsynchronousSampling, aThreadData, nativeStack,
+                  aCollector, aJsFrames, jsFramesCount);
     } else
 #endif
     {
-      MergeStacks(aFeatures, !aLockIfAsynchronousSampling, aThreadData, aRegs,
-                  nativeStack, aCollector, aJsFrames, jsFramesCount);
+      MergeStacks(!aLockIfAsynchronousSampling, aThreadData, nativeStack,
+                  aCollector, aJsFrames, jsFramesCount);
 
       aCollector.CollectNativeLeafAddr((void*)aRegs.mPC);
     }
diff --git a/tools/profiler/moz.build b/tools/profiler/moz.build
index ddb2ce5fff..4d2bf3628f 100644
--- a/tools/profiler/moz.build
+++ b/tools/profiler/moz.build
@@ -85,6 +85,10 @@ if CONFIG["MOZ_GECKO_PROFILER"]:
             UNIFIED_SOURCES += [
                 "core/PowerCounters-linux.cpp",
             ]
+        elif CONFIG["TARGET_CPU"] == "aarch64" and CONFIG["OS_TARGET"] == "Android":
+            SOURCES += [
+                "core/PowerCounters-android.cpp",
+            ]
         if CONFIG["TARGET_CPU"] == "arm" and CONFIG["OS_TARGET"] != "FreeBSD":
             SOURCES += [
                 "core/EHABIStackWalk.cpp",
diff --git a/tools/profiler/public/MicroGeckoProfiler.h b/tools/profiler/public/MicroGeckoProfiler.h
index 7b735e1eec..c23142f07f 100644
--- a/tools/profiler/public/MicroGeckoProfiler.h
+++ b/tools/profiler/public/MicroGeckoProfiler.h
@@ -34,6 +34,10 @@ extern MOZ_EXPORT void uprofiler_unregister_thread();
 extern MOZ_EXPORT void uprofiler_simple_event_marker(
     const char* name, char phase, int num_args, const char** arg_names,
     const unsigned char* arg_types, const unsigned long long* arg_values);
+
+extern MOZ_EXPORT void uprofiler_simple_event_marker_with_stack(
+    const char* name, char phase, int num_args, const char** arg_names,
+    const unsigned char* arg_types, const unsigned long long* arg_values);
 #ifdef __cplusplus
 }
 
@@ -60,6 +64,10 @@ struct UprofilerFuncPtrs {
                               const char** arg_names,
                               const unsigned char* arg_types,
                               const unsigned long long* arg_values);
+  void (*simple_event_marker_with_stack)(const char* name, char phase,
+                                         int num_args, const char** arg_names,
+                                         const unsigned char* arg_types,
+                                         const unsigned long long* arg_values);
 };
 
 #pragma GCC diagnostic push
@@ -77,6 +85,12 @@ static void simple_event_marker_noop(const char* name, char phase, int num_args,
   /* no-op */
 }
 
+static void simple_event_marker_with_stack_noop(
+    const char* name, char phase, int num_args, const char** arg_names,
+    const unsigned char* arg_types, const unsigned long long* arg_values) {
+  /* no-op */
+}
+
 #pragma GCC diagnostic pop
 
 #if defined(_WIN32)
@@ -88,7 +102,7 @@ static void simple_event_marker_noop(const char* name, char phase, int num_args,
 #if defined(_WIN32)
 #  define UPROFILER_GET_SYM(handle, sym) GetProcAddress(handle, sym)
 #else
-#  define UPROFILER_GET_SYM(handle, sym) dlsym(handle, sym)
+#  define UPROFILER_GET_SYM(handle, sym) (typeof(sym)*)(dlsym(handle, #sym))
 #endif
 
 #if defined(_WIN32)
@@ -98,33 +112,30 @@ static void simple_event_marker_noop(const char* name, char phase, int num_args,
     fprintf(stderr, "%s error: %s\n", #func, dlerror());
 #endif
 
+#define FETCH(func)                                             \
+  uprofiler.func = UPROFILER_GET_SYM(handle, uprofiler_##func); \
+  if (!uprofiler.func) {                                        \
+    UPROFILER_PRINT_ERROR(uprofiler_##func);                    \
+    uprofiler.func = func##_noop;                               \
+  }
+
+#define UPROFILER_VISIT()    \
+  FETCH(register_thread)     \
+  FETCH(unregister_thread)   \
+  FETCH(simple_event_marker) \
+  FETCH(simple_event_marker_with_stack)
+
 // Assumes that a variable of type UprofilerFuncPtrs, named uprofiler
 // is accessible in the scope
-#define UPROFILER_GET_FUNCTIONS()                                 \
-  void* handle = UPROFILER_OPENLIB();                             \
-  if (!handle) {                                                  \
-    UPROFILER_PRINT_ERROR(UPROFILER_OPENLIB);                     \
-    uprofiler.register_thread = register_thread_noop;             \
-    uprofiler.unregister_thread = unregister_thread_noop;         \
-    uprofiler.simple_event_marker = simple_event_marker_noop;     \
-  }                                                               \
-  uprofiler.register_thread =                                     \
-      UPROFILER_GET_SYM(handle, "uprofiler_register_thread");     \
-  if (!uprofiler.register_thread) {                               \
-    UPROFILER_PRINT_ERROR(uprofiler_unregister_thread);           \
-    uprofiler.register_thread = register_thread_noop;             \
-  }                                                               \
-  uprofiler.unregister_thread =                                   \
-      UPROFILER_GET_SYM(handle, "uprofiler_unregister_thread");   \
-  if (!uprofiler.unregister_thread) {                             \
-    UPROFILER_PRINT_ERROR(uprofiler_unregister_thread);           \
-    uprofiler.unregister_thread = unregister_thread_noop;         \
-  }                                                               \
-  uprofiler.simple_event_marker =                                 \
-      UPROFILER_GET_SYM(handle, "uprofiler_simple_event_marker"); \
-  if (!uprofiler.simple_event_marker) {                           \
-    UPROFILER_PRINT_ERROR(uprofiler_simple_event_marker);         \
-    uprofiler.simple_event_marker = simple_event_marker_noop;     \
-  }
+#define UPROFILER_GET_FUNCTIONS()                                            \
+  void* handle = UPROFILER_OPENLIB();                                        \
+  if (!handle) {                                                             \
+    UPROFILER_PRINT_ERROR(UPROFILER_OPENLIB);                                \
+    uprofiler.register_thread = register_thread_noop;                        \
+    uprofiler.unregister_thread = unregister_thread_noop;                    \
+    uprofiler.simple_event_marker = simple_event_marker_noop;                \
+    uprofiler.simple_event_marker_with_stack = simple_event_with_stack_noop; \
+  }                                                                          \
+  UPROFILER_VISIT()
 
 #endif  // MICRO_GECKO_PROFILER
diff --git a/tools/profiler/public/ProfilerControl.h b/tools/profiler/public/ProfilerControl.h
index 466d15eb69..ac145fac00 100644
--- a/tools/profiler/public/ProfilerControl.h
+++ b/tools/profiler/public/ProfilerControl.h
@@ -40,6 +40,8 @@ static inline void profiler_init(void* stackTop) {}
 static inline void profiler_shutdown(
     IsFastShutdown aIsFastShutdown = IsFastShutdown::No) {}
 
+static inline void profiler_lookup_download_directory() {}
+
 #else  // !MOZ_GECKO_PROFILER
 
 #  include "BaseProfiler.h"
@@ -123,6 +125,18 @@ void profiler_ensure_started(
     const char** aFilters, uint32_t aFilterCount, uint64_t aActiveTabID,
     const mozilla::Maybe<double>& aDuration = mozilla::Nothing());
 
+// Tell the profiler to look up the download directory for writing profiles.
+// With some features, such as signal control, we need to know the location of
+// a directory where we can save profiles to disk. Because we start the
+// profiler before we start the directory service, we can't access the
+// download directory at profiler startup. Similarly, when we need to get the
+// directory, we often can't, as we're running in non-main-thread contexts
+// that don't have access to the directory service. This function gives us a
+// third option, by giving us a hook to look for the download directory when
+// the time is right. This might be triggered internally (e.g. when we start
+// profiling), or externally, e.g. after the directory service is initialised.
+void profiler_lookup_download_directory();
+
 //---------------------------------------------------------------------------
 // Control the profiler
 //---------------------------------------------------------------------------
diff --git a/tools/profiler/tests/xpcshell/test_feature_posix_signals.js b/tools/profiler/tests/xpcshell/test_feature_posix_signals.js
new file mode 100644
index 0000000000..28fbf890e8
--- /dev/null
+++ b/tools/profiler/tests/xpcshell/test_feature_posix_signals.js
@@ -0,0 +1,194 @@
+/* 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/. */
+
+ChromeUtils.defineESModuleGetters(this, {
+  Downloads: "resource://gre/modules/Downloads.sys.mjs",
+  FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
+  BrowserTestUtils: "resource://testing-common/BrowserTestUtils.sys.mjs",
+});
+
+const { ctypes } = ChromeUtils.importESModule(
+  "resource://gre/modules/ctypes.sys.mjs"
+);
+
+// Derived from functionality in js/src/devtools/rootAnalysis/utility.js
+function openLibrary(names) {
+  for (const name of names) {
+    try {
+      return ctypes.open(name);
+    } catch (e) {}
+  }
+  return undefined;
+}
+
+// Derived heavily from equivalent sandbox testing code.
+// For more details see:
+// https://searchfox.org/mozilla-central/rev/1aaacaeb4fa3aca6837ecc157e43e947229ba8ce/security/sandbox/test/browser_content_sandbox_utils.js#89
+function raiseSignal(pid, sig) {
+  try {
+    const libc = openLibrary([
+      "libc.so.6",
+      "libc.so",
+      "libc.dylib",
+      "libSystem.B.dylib",
+    ]);
+    if (!libc) {
+      info("Failed to open any libc shared object");
+      return { ok: false };
+    }
+
+    // c.f. https://man7.org/linux/man-pages/man2/kill.2.html
+    // This choice of typing for `pid` is complex, and brittle, as it's
+    // platform dependent. Getting it wrong can result in incoreect
+    //  generation/calling of the `kill` function. Unfortunately, as it's
+    // defined as `pid_t` in a header, we can't easily get access to it.
+    // For now, we just use an integer, and hope that the system int size
+    // aligns with the `pid_t` size.
+    const kill = libc.declare(
+      "kill",
+      ctypes.default_abi,
+      ctypes.int, // return value
+      ctypes.int32_t, // pid
+      ctypes.int // sig
+    );
+
+    let kres = kill(pid, sig);
+    if (kres != 0) {
+      info(`Kill returned a non-zero result ${kres}.`);
+      return { ok: false };
+    }
+
+    libc.close();
+  } catch (e) {
+    info(`Exception ${e} thrown while trying to call kill`);
+    return { ok: false };
+  }
+
+  return { ok: true };
+}
+
+// We would like to use the following to wait for a stop signal to actually be
+// handled:
+//  await Services.profiler.waitOnePeriodicSampling();
+// However, as we are trying to shut down the profiler using the sampler
+// thread, this can cause complications between the callback waiting for the
+// sampling to be over, and the sampler thread actually finishing.
+// Instead, we use the BrowserTestUtils.waitForCondition to wait until the
+// profiler is no longer active.
+async function waitUntilProfilerStopped(interval = 1000, maxTries = 100) {
+  await BrowserTestUtils.waitForCondition(
+    () => !Services.profiler.IsActive(),
+    "the profiler should be inactive",
+    interval,
+    maxTries
+  );
+}
+
+async function cleanupAfterTest() {
+  // We need to cleanup written profiles after a test
+  // Get the system downloads directory, and use it to build a profile file
+  let profile = FileUtils.File(await Downloads.getSystemDownloadsDirectory());
+
+  // Get the process ID
+  let pid = Services.appinfo.processID;
+
+  // write it to the profile file name
+  profile.append(`profile_0_${pid}.json`);
+
+  // remove the file!
+  await IOUtils.remove(profile.path, { ignoreAbsent: true });
+
+  // Make sure the profiler is fully stopped, even if the test failed
+  await Services.profiler.StopProfiler();
+}
+
+// Hardcode the constants SIGUSR1 and SIGUSR2.
+// This is an absolutely terrible idea, as they are implementation defined!
+// However, it turns out that for 99% of the platforms we care about, and for
+// 99.999% of the platforms we test, these constants are, well, constant.
+// Additionally, these constants are only for _testing_ the signal handling
+// feature - the actual feature relies on platform specific definitions. This
+//  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 SIGUSR2 = Services.appinfo.OS === "Darwin" ? 31 : 12;
+
+add_task(async () => {
+  info("Test that stopping the profiler with a posix signal works.");
+  registerCleanupFunction(cleanupAfterTest);
+
+  Assert.ok(
+    !Services.profiler.IsActive(),
+    "The profiler should not begin the test active."
+  );
+
+  const entries = 100;
+  const interval = 1;
+  const threads = [];
+  const features = [];
+
+  // Start the profiler, and ensure that it's active
+  await Services.profiler.StartProfiler(entries, interval, threads, features);
+  Assert.ok(Services.profiler.IsActive(), "The profiler should now be active.");
+
+  // Get the process ID
+  let pid = Services.appinfo.processID;
+
+  // Try and stop the profiler using a signal.
+  let result = raiseSignal(pid, SIGUSR2);
+  Assert.ok(result, "Raising a SIGUSR2 signal should succeed.");
+
+  await waitUntilProfilerStopped();
+
+  do_test_finished();
+});
+
+add_task(async () => {
+  info(
+    "Test that stopping the profiler with a posix signal writes a profile file to the system download directory."
+  );
+  registerCleanupFunction(cleanupAfterTest);
+
+  Assert.ok(
+    !Services.profiler.IsActive(),
+    "The profiler should not begin the test active."
+  );
+
+  const entries = 100;
+  const interval = 1;
+  const threads = [];
+  const features = [];
+
+  // Get the system downloads directory, and use it to build a profile file
+  let profile = FileUtils.File(await Downloads.getSystemDownloadsDirectory());
+
+  // Get the process ID
+  let pid = Services.appinfo.processID;
+
+  // use the pid to construct the name of the profile, and resulting file
+  profile.append(`profile_0_${pid}.json`);
+
+  // Start the profiler, and ensure that it's active
+  await Services.profiler.StartProfiler(entries, interval, threads, features);
+  Assert.ok(Services.profiler.IsActive(), "The profiler should now be active.");
+
+  // 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."
+  );
+
+  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 5c094899a4..2cde39d09f 100644
--- a/tools/profiler/tests/xpcshell/xpcshell.toml
+++ b/tools/profiler/tests/xpcshell/xpcshell.toml
@@ -24,9 +24,6 @@ skip-if = ["!debug"]
 ["test_feature_fileioall.js"]
 skip-if = ["release_or_beta"]
 
-# The sanitizer checks appears to overwrite our own memory hooks in xpcshell tests,
-# and no allocation markers are gathered. Skip this test in that configuration.
-
 ["test_feature_java.js"]
 skip-if = ["os != 'android'"]
 
@@ -50,6 +47,12 @@ skip-if = [
   "socketprocess_networking",
 ]
 
+["test_feature_posix_signals.js"]
+skip-if = [
+  "ccov",
+  "os == 'win'",
+]
+
 # Native stackwalking is somewhat unreliable depending on the platform.
 #
 # We don't have frame pointers on macOS release and beta, so stack walking does not
@@ -61,6 +64,9 @@ skip-if = [
 # For sanitizer builds, there were many intermittents, and we're not getting much
 # additional coverage there, so it's better to be a bit more reliable.
 
+# The sanitizer checks appears to overwrite our own memory hooks in xpcshell tests,
+# and no allocation markers are gathered. Skip this test in that configuration.
+
 ["test_feature_stackwalking.js"]
 skip-if = [
   "os == 'mac' && release_or_beta",