Archive/naiveproxy/src/base/allocator/partition_alloc_support.cc

// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/allocator/partition_alloc_support.h"

#include <algorithm>
#include <array>
#include <cinttypes>
#include <cstdint>
#include <map>
#include <optional>
#include <string>
#include <string_view>

#include "base/allocator/partition_alloc_features.h"
#include "base/at_exit.h"
#include "base/check.h"
#include "base/containers/span.h"
#include "base/cpu.h"
#include "base/debug/dump_without_crashing.h"
#include "base/debug/stack_trace.h"
#include "base/debug/task_trace.h"
#include "base/feature_list.h"
#include "base/functional/bind.h"
#include "base/functional/callback.h"
#include "base/immediate_crash.h"
#include "base/location.h"
#include "base/memory/post_delayed_memory_reduction_task.h"
#include "base/memory/raw_ptr_asan_service.h"
#include "base/metrics/histogram_functions.h"
#include "base/metrics/histogram_macros.h"
#include "base/no_destructor.h"
#include "base/pending_task.h"
#include "base/strings/string_split.h"
#include "base/strings/stringprintf.h"
#include "base/system/sys_info.h"
#include "base/task/single_thread_task_runner.h"
#include "base/thread_annotations.h"
#include "base/threading/platform_thread.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "base/trace_event/base_tracing.h"
#include "build/build_config.h"
#include "partition_alloc/allocation_guard.h"
#include "partition_alloc/buildflags.h"
#include "partition_alloc/dangling_raw_ptr_checks.h"
#include "partition_alloc/memory_reclaimer.h"
#include "partition_alloc/page_allocator.h"
#include "partition_alloc/partition_alloc_base/debug/alias.h"
#include "partition_alloc/partition_alloc_base/immediate_crash.h"
#include "partition_alloc/partition_alloc_base/threading/platform_thread.h"
#include "partition_alloc/partition_alloc_check.h"
#include "partition_alloc/partition_alloc_config.h"
#include "partition_alloc/partition_alloc_constants.h"
#include "partition_alloc/partition_lock.h"
#include "partition_alloc/partition_root.h"
#include "partition_alloc/pointers/instance_tracer.h"
#include "partition_alloc/pointers/raw_ptr.h"
#include "partition_alloc/shim/allocator_shim.h"
#include "partition_alloc/shim/allocator_shim_default_dispatch_to_partition_alloc.h"
#include "partition_alloc/shim/allocator_shim_dispatch_to_noop_on_free.h"
#include "partition_alloc/stack/stack.h"
#include "partition_alloc/thread_cache.h"

#if BUILDFLAG(IS_ANDROID)
#include "base/system/sys_info.h"
#endif

#if PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
#include "partition_alloc/memory_reclaimer.h"
#endif

#if PA_BUILDFLAG( \
    ENABLE_ALLOCATOR_SHIM_PARTITION_ALLOC_DISPATCH_WITH_ADVANCED_CHECKS_SUPPORT)
#include "partition_alloc/shim/allocator_shim_default_dispatch_to_partition_alloc_with_advanced_checks.h"
#endif

#if BUILDFLAG(IS_ANDROID) && PA_BUILDFLAG(HAS_MEMORY_TAGGING)
#include <sys/system_properties.h>
#endif

namespace base::allocator {

namespace {

#if BUILDFLAG(IS_ANDROID) && PA_BUILDFLAG(HAS_MEMORY_TAGGING)
enum class BootloaderOverride {
  kDefault,
  kForceOn,
  kForceOff,
};

BootloaderOverride GetBootloaderOverride() {
  char bootloader_override_str[PROP_VALUE_MAX];
  __system_property_get(
      "persist.device_config.runtime_native_boot.bootloader_override",
      bootloader_override_str);

  if (strcmp(bootloader_override_str, "force_on") == 0) {
    return BootloaderOverride::kForceOn;
  }
  if (strcmp(bootloader_override_str, "force_off") == 0) {
    return BootloaderOverride::kForceOff;
  }
  return BootloaderOverride::kDefault;
}
#endif

// When under this experiment avoid running periodic purging or reclaim for the
// first minute after the first attempt. This is based on the insight that
// processes often don't live paste this minute.
static BASE_FEATURE(kDelayFirstPeriodicPAPurgeOrReclaim,
                    "DelayFirstPeriodicPAPurgeOrReclaim",
                    base::FEATURE_ENABLED_BY_DEFAULT);
constexpr base::TimeDelta kFirstPAPurgeOrReclaimDelay = base::Minutes(1);

// This is defined in content/public/common/content_switches.h, which is not
// accessible in ::base. They must be kept in sync.
namespace switches {
[[maybe_unused]] constexpr char kRendererProcess[] = "renderer";
constexpr char kZygoteProcess[] = "zygote";
}  // namespace switches

}  // namespace

namespace {

void RunThreadCachePeriodicPurge() {
  // Micros, since periodic purge should typically take at most a few ms.
  SCOPED_UMA_HISTOGRAM_TIMER_MICROS("Memory.PartitionAlloc.PeriodicPurge");
  TRACE_EVENT0("memory", "PeriodicPurge");
  auto& instance = ::partition_alloc::ThreadCacheRegistry::Instance();
  instance.RunPeriodicPurge();
  TimeDelta delay =
      Microseconds(instance.GetPeriodicPurgeNextIntervalInMicroseconds());
  SingleThreadTaskRunner::GetCurrentDefault()->PostDelayedTask(
      FROM_HERE, BindOnce(RunThreadCachePeriodicPurge), delay);
}

}  // namespace

// When enabled, disable the memory reclaimer in background.
BASE_FEATURE(kDisableMemoryReclaimerInBackground,
             "DisableMemoryReclaimerInBackground",
             base::FEATURE_ENABLED_BY_DEFAULT);

// When enabled, limit the time memory reclaimer may take, returning early when
// exceeded.
BASE_FEATURE(kPartitionAllocShortMemoryReclaim,
             "PartitionAllocShortMemoryReclaim",
             base::FEATURE_ENABLED_BY_DEFAULT);

// static
MemoryReclaimerSupport& MemoryReclaimerSupport::Instance() {
  static base::NoDestructor<MemoryReclaimerSupport> instance;
  return *instance.get();
}
MemoryReclaimerSupport::~MemoryReclaimerSupport() = default;

MemoryReclaimerSupport::MemoryReclaimerSupport() = default;

void MemoryReclaimerSupport::Start(scoped_refptr<TaskRunner> task_runner) {
  if (!base::FeatureList::IsEnabled(
          base::features::kPartitionAllocMemoryReclaimer)) {
    return;
  }

  // Can be called several times.
  if (has_pending_task_) {
    return;
  }

  // The caller of the API fully controls where running the reclaim.
  // However there are a few reasons to recommend that the caller runs
  // it on the main thread:
  // - Most of PartitionAlloc's usage is on the main thread, hence PA's metadata
  //   is more likely in cache when executing on the main thread.
  // - Memory reclaim takes the partition lock for each partition. As a
  //   consequence, while reclaim is running, the main thread is unlikely to be
  //   able to make progress, as it would be waiting on the lock.
  // - Finally, this runs in idle time only, so there should be no visible
  //   impact.
  //
  // From local testing, time to reclaim is 100us-1ms, and reclaiming every few
  // seconds is useful. Since this is meant to run during idle time only, it is
  // a reasonable starting point balancing effectivenes vs cost. See
  // crbug.com/942512 for details and experimental results.
  TimeDelta delay;
  if (base::FeatureList::IsEnabled(kDelayFirstPeriodicPAPurgeOrReclaim)) {
    delay = std::max(delay, kFirstPAPurgeOrReclaimDelay);
  }

  task_runner_ = task_runner;
  MaybeScheduleTask(delay);
}

void MemoryReclaimerSupport::SetForegrounded(bool in_foreground) {
  in_foreground_ = in_foreground;
  if (in_foreground_) {
    MaybeScheduleTask();
  }
}

void MemoryReclaimerSupport::ResetForTesting() {
  task_runner_ = nullptr;
  has_pending_task_ = false;
  in_foreground_ = true;
}

void MemoryReclaimerSupport::Run() {
  TRACE_EVENT0("base", "partition_alloc::MemoryReclaimer::Reclaim()");
  has_pending_task_ = false;

  {
    // Micros, since memory reclaiming should typically take at most a few ms.
    SCOPED_UMA_HISTOGRAM_TIMER_MICROS("Memory.PartitionAlloc.MemoryReclaim");
    if (base::FeatureList::IsEnabled(kPartitionAllocShortMemoryReclaim)) {
      ::partition_alloc::MemoryReclaimer::Instance()->ReclaimFast();
    } else {
      ::partition_alloc::MemoryReclaimer::Instance()->ReclaimNormal();
    }
  }

  MaybeScheduleTask();
}

// static
TimeDelta MemoryReclaimerSupport::GetInterval() {
  TimeDelta delay = features::kPartitionAllocMemoryReclaimerInterval.Get();
  if (delay.is_positive()) {
    return delay;
  }

  return Microseconds(::partition_alloc::MemoryReclaimer::Instance()
                          ->GetRecommendedReclaimIntervalInMicroseconds());
}

void MemoryReclaimerSupport::MaybeScheduleTask(TimeDelta delay) {
  if (has_pending_task_ ||
      (base::FeatureList::IsEnabled(kDisableMemoryReclaimerInBackground) &&
       !in_foreground_) ||
      !task_runner_) {
    return;
  }

  has_pending_task_ = true;
  TimeDelta actual_delay = std::max(delay, GetInterval());
  task_runner_->PostDelayedTask(
      FROM_HERE, BindOnce(&MemoryReclaimerSupport::Run, base::Unretained(this)),
      actual_delay);
}

void StartThreadCachePeriodicPurge() {
  auto& instance = ::partition_alloc::ThreadCacheRegistry::Instance();
  TimeDelta delay =
      Microseconds(instance.GetPeriodicPurgeNextIntervalInMicroseconds());

  if (base::FeatureList::IsEnabled(kDelayFirstPeriodicPAPurgeOrReclaim)) {
    delay = std::max(delay, kFirstPAPurgeOrReclaimDelay);
  }

  SingleThreadTaskRunner::GetCurrentDefault()->PostDelayedTask(
      FROM_HERE, BindOnce(RunThreadCachePeriodicPurge), delay);
}

void StartMemoryReclaimer(scoped_refptr<SequencedTaskRunner> task_runner) {
  MemoryReclaimerSupport::Instance().Start(task_runner);
}

std::map<std::string, std::string> ProposeSyntheticFinchTrials() {
  std::map<std::string, std::string> trials;

#if PA_BUILDFLAG(ENABLE_DANGLING_RAW_PTR_CHECKS)
  trials.emplace("DanglingPointerDetector", "Enabled");
#else
  trials.emplace("DanglingPointerDetector", "Disabled");
#endif

  // This value is not surrounded by build flags as it is meant to be updated
  // manually in binary experiment patches.
  trials.emplace("VectorRawPtrExperiment", "Disabled");

#if PA_BUILDFLAG(HAS_MEMORY_TAGGING)
  if (base::FeatureList::IsEnabled(
          base::features::kPartitionAllocMemoryTagging)) {
    bool has_mte = base::CPU::GetInstanceNoAllocation().has_mte();
    if (has_mte) {
      trials.emplace("MemoryTaggingDogfood", "Enabled");
    } else {
      trials.emplace("MemoryTaggingDogfood", "Disabled");
    }
#if BUILDFLAG(IS_ANDROID)
    BootloaderOverride bootloader_override = GetBootloaderOverride();
    partition_alloc::TagViolationReportingMode reporting_mode =
        partition_alloc::TagViolationReportingMode::kUndefined;
#if PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
    reporting_mode = allocator_shim::internal::PartitionAllocMalloc::Allocator()
                         ->memory_tagging_reporting_mode();
#endif  // PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
    switch (bootloader_override) {
      case BootloaderOverride::kDefault:
        trials.emplace("MemoryTaggingBootloaderOverride", "Default");
        break;
      case BootloaderOverride::kForceOn:
        if (has_mte) {
          switch (reporting_mode) {
            case partition_alloc::TagViolationReportingMode::kAsynchronous:
              trials.emplace("MemoryTaggingBootloaderOverride", "ForceOnAsync");
              break;
            case partition_alloc::TagViolationReportingMode::kSynchronous:
              // This should not happen unless user forces it.
              trials.emplace("MemoryTaggingBootloaderOverride", "ForceOnSync");
              break;
            default:
              // This should not happen unless user forces it.
              trials.emplace("MemoryTaggingBootloaderOverride",
                             "ForceOnDisabled");
          }
        } else {
          // This should not happen unless user forces it.
          trials.emplace("MemoryTaggingBootloaderOverride",
                         "ForceOnWithoutMte");
        }
        break;
      case BootloaderOverride::kForceOff:
        if (!has_mte) {
          trials.emplace("MemoryTaggingBootloaderOverride", "ForceOff");
        } else {
          // This should not happen unless user forces it.
          trials.emplace("MemoryTaggingBootloaderOverride", "ForceOffWithMte");
        }
        break;
    }
#endif  // BUILDFLAG(IS_ANDROID)
  }
#endif  // PA_BUILDFLAG(HAS_MEMORY_TAGGING)

  return trials;
}

namespace {

bool ShouldEnableFeatureOnProcess(
    features::internal::PAFeatureEnabledProcesses enabled_processes,
    const std::string& process_type) {
  switch (enabled_processes) {
    case features::internal::PAFeatureEnabledProcesses::kBrowserOnly:
      return process_type.empty();
    case features::internal::PAFeatureEnabledProcesses::kNonRenderer:
      return process_type != switches::kRendererProcess;
    case features::internal::PAFeatureEnabledProcesses::kBrowserAndRenderer:
      return process_type.empty() || process_type == switches::kRendererProcess;
    case features::internal::PAFeatureEnabledProcesses::kRendererOnly:
      return process_type == switches::kRendererProcess;
    case features::internal::PAFeatureEnabledProcesses::kAllChildProcesses:
      return !process_type.empty() && process_type != switches::kZygoteProcess;
    case features::internal::PAFeatureEnabledProcesses::kAllProcesses:
      return true;
  }
}

#if PA_CONFIG(ENABLE_SHADOW_METADATA)
bool ShouldEnableShadowMetadata(const std::string& process_type) {
  if (!base::FeatureList::IsEnabled(
          base::features::kPartitionAllocShadowMetadata)) {
    return false;
  }
  return ShouldEnableFeatureOnProcess(
      features::kShadowMetadataEnabledProcessesParam.Get(), process_type);
}
#endif  // PA_CONFIG(ENABLE_SHADOW_METADATA)

}  // namespace

#if PA_BUILDFLAG(ENABLE_DANGLING_RAW_PTR_CHECKS)

namespace {

internal::PartitionLock g_stack_trace_buffer_lock;

constexpr size_t kDanglingPtrStackTraceSize =
    PA_BUILDFLAG(IS_DEBUG)
        ? 32  // Symbolizing large stack traces can be expensive in debug
              // builds. We prefer displaying a reasonably sized one instead
              // of timing out.
        : base::debug::StackTrace::kMaxTraces;

struct DanglingPointerFreeInfo {
  debug::StackTrace stack_trace;
  debug::TaskTrace task_trace;
  uintptr_t id = 0;
};
using DanglingRawPtrBuffer =
    std::array<std::optional<DanglingPointerFreeInfo>, 32>;
DanglingRawPtrBuffer g_stack_trace_buffer GUARDED_BY(g_stack_trace_buffer_lock);

void DanglingRawPtrDetected(uintptr_t id) {
  // This is called from inside the allocator. No allocation is allowed.

  internal::PartitionAutoLock guard(g_stack_trace_buffer_lock);

#if DCHECK_IS_ON()
  for (std::optional<DanglingPointerFreeInfo>& entry : g_stack_trace_buffer) {
    PA_DCHECK(!entry || entry->id != id);
  }
#endif  // DCHECK_IS_ON()

  for (std::optional<DanglingPointerFreeInfo>& entry : g_stack_trace_buffer) {
    if (!entry) {
      entry = {
          debug::StackTrace(kDanglingPtrStackTraceSize),
          debug::TaskTrace(),
          id,
      };
      return;
    }
  }

  // The StackTrace hasn't been recorded, because the buffer isn't large
  // enough.
}

// From the traces recorded in |DanglingRawPtrDetected|, extract the one
// whose id match |id|. Return nullopt if not found.
std::optional<DanglingPointerFreeInfo> TakeDanglingPointerFreeInfo(
    uintptr_t id) {
  internal::PartitionAutoLock guard(g_stack_trace_buffer_lock);
  for (std::optional<DanglingPointerFreeInfo>& entry : g_stack_trace_buffer) {
    if (entry && entry->id == id) {
      std::optional<DanglingPointerFreeInfo> result(entry);
      entry = std::nullopt;
      return result;
    }
  }
  return std::nullopt;
}

// Extract from the StackTrace output, the signature of the pertinent caller.
// This function is meant to be used only by Chromium developers, to list what
// are all the dangling raw_ptr occurrences in a table.
std::string ExtractDanglingPtrSignature(std::string stacktrace) {
  std::vector<std::string_view> lines = SplitStringPiece(
      stacktrace, "\r\n", KEEP_WHITESPACE, SPLIT_WANT_NONEMPTY);

  // We are looking for the callers of the function releasing the raw_ptr and
  // freeing memory. This lists potential matching patterns. A pattern is a list
  // of substrings that are all required to match.
  const std::vector<std::string_view> callee_patterns[] = {
      // Common signature patters:
      {"internal::PartitionFree"},
      {"base::", "::FreeFn"},
      {"internal::RawPtrBackupRefImpl", "::ReleaseInternal"},

      // Linux specific:
      {"base::RefCountedThreadSafe<>::Release"},

      // Windows specific:
      {"_free_base"},

      // Task traces are prefixed with "Task trace:" in
      // |TaskTrace::OutputToStream|
      {"Task trace:"},
  };
  size_t caller_index = 0;
  for (size_t i = 0; i < lines.size(); ++i) {
    for (const auto& patterns : callee_patterns) {
      if (std::ranges::all_of(patterns, [&](std::string_view pattern) {
            return lines[i].find(pattern) != std::string_view::npos;
          })) {
        caller_index = i + 1;
      }
    }
  }
  if (caller_index >= lines.size()) {
    return "no_callee_match";
  }
  std::string_view caller = lines[caller_index];

  if (caller.empty()) {
    return "invalid_format";
  }

  // On Posix platforms |callers| follows the following format:
  //
  // #<index> <address> <symbol>
  //
  // See https://crsrc.org/c/base/debug/stack_trace_posix.cc
  if (caller[0] == '#') {
    const size_t address_start = caller.find(' ');
    const size_t function_start = caller.find(' ', address_start + 1);

    if (address_start == caller.npos || function_start == caller.npos) {
      return "invalid_format";
    }

    return std::string(caller.substr(function_start + 1));
  }

  // On Windows platforms |callers| follows the following format:
  //
  // \t<symbol> [0x<address>]+<displacement>(<filename>:<line>)
  //
  // See https://crsrc.org/c/base/debug/stack_trace_win.cc
  if (caller[0] == '\t') {
    const size_t symbol_start = 1;
    const size_t symbol_end = caller.find(' ');
    if (symbol_end == caller.npos) {
      return "invalid_format";
    }
    return std::string(caller.substr(symbol_start, symbol_end - symbol_start));
  }

  // On Mac platforms |callers| follows the following format:
  //
  // <index> <library> 0x<address> <symbol> + <line>
  //
  // See https://crsrc.org/c/base/debug/stack_trace_posix.cc
  if (caller[0] >= '0' && caller[0] <= '9') {
    const size_t address_start = caller.find("0x");
    const size_t symbol_start = caller.find(' ', address_start + 1) + 1;
    const size_t symbol_end = caller.find(' ', symbol_start);
    if (symbol_start == caller.npos || symbol_end == caller.npos) {
      return "invalid_format";
    }
    return std::string(caller.substr(symbol_start, symbol_end - symbol_start));
  }

  return "invalid_format";
}

std::string ExtractDanglingPtrSignature(debug::TaskTrace task_trace) {
  if (task_trace.empty()) {
    return "No active task";
  }
  return ExtractDanglingPtrSignature(task_trace.ToString());
}

std::string ExtractDanglingPtrSignature(
    std::optional<DanglingPointerFreeInfo> free_info,
    debug::StackTrace release_stack_trace,
    debug::TaskTrace release_task_trace) {
  if (free_info) {
    return StringPrintf(
        "[DanglingSignature]\t%s\t%s\t%s\t%s",
        ExtractDanglingPtrSignature(free_info->stack_trace.ToString()).c_str(),
        ExtractDanglingPtrSignature(free_info->task_trace).c_str(),
        ExtractDanglingPtrSignature(release_stack_trace.ToString()).c_str(),
        ExtractDanglingPtrSignature(release_task_trace).c_str());
  }
  return StringPrintf(
      "[DanglingSignature]\t%s\t%s\t%s\t%s", "missing", "missing",
      ExtractDanglingPtrSignature(release_stack_trace.ToString()).c_str(),
      ExtractDanglingPtrSignature(release_task_trace).c_str());
}

bool operator==(const debug::TaskTrace& lhs, const debug::TaskTrace& rhs) {
  // Compare the addresses contained in the task traces.
  // The task traces are at most |PendingTask::kTaskBacktraceLength| long.
  std::array<const void*, PendingTask::kTaskBacktraceLength> addresses_lhs = {};
  std::array<const void*, PendingTask::kTaskBacktraceLength> addresses_rhs = {};
  lhs.GetAddresses(addresses_lhs);
  rhs.GetAddresses(addresses_rhs);
  return addresses_lhs == addresses_rhs;
}

template <features::DanglingPtrMode dangling_pointer_mode,
          features::DanglingPtrType dangling_pointer_type>
void DanglingRawPtrReleased(uintptr_t id) {
  // This is called from raw_ptr<>'s release operation. Making allocations is
  // allowed. In particular, symbolizing and printing the StackTraces may
  // allocate memory.

  debug::StackTrace stack_trace_release(kDanglingPtrStackTraceSize);
  debug::TaskTrace task_trace_release;
  std::optional<DanglingPointerFreeInfo> free_info =
      TakeDanglingPointerFreeInfo(id);

  if constexpr (dangling_pointer_type ==
                features::DanglingPtrType::kCrossTask) {
    if (!free_info) {
      return;
    }
    if (task_trace_release == free_info->task_trace) {
      return;
    }
  }

  std::string dangling_signature = ExtractDanglingPtrSignature(
      free_info, stack_trace_release, task_trace_release);

  {
    // Log the full error in a single LogMessage. Printing StackTrace is
    // expensive, so we want to avoid interleaving the output with other logs.
    logging::LogMessage log_message(__FILE__, __LINE__, logging::LOGGING_ERROR);
    std::ostream& error = log_message.stream();

    // The dangling signature can be used by script to locate the origin of
    // every dangling pointers.
    error << "\n\n"
          << ExtractDanglingPtrSignature(free_info, stack_trace_release,
                                         task_trace_release)
          << "\n\n";

    error << "[DanglingPtr](1/3) A raw_ptr/raw_ref is dangling.\n\n";

    auto print_traces = [](debug::StackTrace stack_trace,
                           debug::TaskTrace task_trace, std::ostream& error) {
      error << "Stack trace:\n";
      error << stack_trace << "\n";

      // Printing "Task trace:" is implied by the TaskTrace itself.
      if (!task_trace.empty()) {
        error << task_trace << "\n";
      }
    };

    error << "[DanglingPtr](2/3) ";
    if (free_info) {
      error << "First, the memory was freed at:\n\n";
      print_traces(free_info->stack_trace, free_info->task_trace, error);
    } else {
      error << "It was not recorded where the memory was freed.\n";
    }

    error << "[DanglingPtr](3/3) Later, the dangling raw_ptr was released "
             "at:\n\n";
    print_traces(stack_trace_release, task_trace_release, error);

    error << "Please check for more information on:\n";
    error << "https://chromium.googlesource.com/chromium/src/+/main/docs/";
    error << "dangling_ptr_guide.md\n";
    error << "\n";
  }

  if constexpr (dangling_pointer_mode == features::DanglingPtrMode::kCrash) {
    // We use `PA_IMMEDIATE_CRASH()` instead of base's ImmediateCrash() to avoid
    // printing the raw_ptr release stack trace twice.
    PA_IMMEDIATE_CRASH();
  }
}

void CheckDanglingRawPtrBufferEmpty() {
  internal::PartitionAutoLock guard(g_stack_trace_buffer_lock);

  // TODO(crbug.com/40260713): Check for leaked refcount on Android.
#if BUILDFLAG(IS_ANDROID)
  g_stack_trace_buffer = DanglingRawPtrBuffer();
#else
  bool errors = false;
  for (auto entry : g_stack_trace_buffer) {
    if (!entry) {
      continue;
    }
    errors = true;
    LOG(ERROR) << "A freed allocation is still referenced by a dangling "
                  "pointer at exit, or at test end. Leaked raw_ptr/raw_ref "
                  "could cause PartitionAlloc's quarantine memory bloat."
                  "\n\n"
                  "Memory was released on:\n"
               << entry->task_trace << "\n"
               << entry->stack_trace << "\n";
#if PA_BUILDFLAG(ENABLE_BACKUP_REF_PTR_INSTANCE_TRACER)
    auto is_frame_ptr_not_null = [](const void* frame_ptr) {
      return frame_ptr != nullptr;
    };
    std::vector<std::array<const void*, 32>> stack_traces =
        internal::InstanceTracer::GetStackTracesForDanglingRefs(entry->id);
    for (const auto& raw_stack_trace : stack_traces) {
      CHECK(std::ranges::is_partitioned(raw_stack_trace, is_frame_ptr_not_null))
          << "`raw_stack_trace` is expected to be partitioned: non-null values "
             "at the begining followed by `nullptr`s.";
      LOG(ERROR) << "Dangling reference from:\n";
      LOG(ERROR) << debug::StackTrace(
                        // This call truncates the `nullptr` tail of the stack
                        // trace (see the `is_partitioned` CHECK above).
                        span(raw_stack_trace.begin(),
                             std::ranges::partition_point(
                                 raw_stack_trace, is_frame_ptr_not_null)))
                 << "\n";
    }
#else
    LOG(ERROR) << "Building with enable_backup_ref_ptr_instance_tracer will "
                  "print out stack traces of any live but dangling references.";
#endif
  }
  CHECK(!errors);
#endif
}

}  // namespace

void InstallDanglingRawPtrChecks() {
  // Multiple tests can run within the same executable's execution. This line
  // ensures problems detected from the previous test are causing error before
  // entering the next one...
  CheckDanglingRawPtrBufferEmpty();

  // ... similarly, some allocation may stay forever in the quarantine and we
  // might ignore them if the executable exists. This line makes sure dangling
  // pointers errors are never ignored, by crashing at exit, as a last resort.
  // This makes quarantine memory bloat more likely to be detected.
  static bool first_run_in_process = true;
  if (first_run_in_process) {
    first_run_in_process = false;
    AtExitManager::RegisterTask(base::BindOnce(CheckDanglingRawPtrBufferEmpty));
  }

  if (!FeatureList::IsEnabled(features::kPartitionAllocDanglingPtr)) {
    partition_alloc::SetDanglingRawPtrDetectedFn([](uintptr_t) {});
    partition_alloc::SetDanglingRawPtrReleasedFn([](uintptr_t) {});
    return;
  }

  partition_alloc::SetDanglingRawPtrDetectedFn(&DanglingRawPtrDetected);
  switch (features::kDanglingPtrModeParam.Get()) {
    case features::DanglingPtrMode::kCrash:
      switch (features::kDanglingPtrTypeParam.Get()) {
        case features::DanglingPtrType::kAll:
          partition_alloc::SetDanglingRawPtrReleasedFn(
              &DanglingRawPtrReleased<features::DanglingPtrMode::kCrash,
                                      features::DanglingPtrType::kAll>);
          break;
        case features::DanglingPtrType::kCrossTask:
          partition_alloc::SetDanglingRawPtrReleasedFn(
              &DanglingRawPtrReleased<features::DanglingPtrMode::kCrash,
                                      features::DanglingPtrType::kCrossTask>);
          break;
      }
      break;
    case features::DanglingPtrMode::kLogOnly:
      switch (features::kDanglingPtrTypeParam.Get()) {
        case features::DanglingPtrType::kAll:
          partition_alloc::SetDanglingRawPtrReleasedFn(
              &DanglingRawPtrReleased<features::DanglingPtrMode::kLogOnly,
                                      features::DanglingPtrType::kAll>);
          break;
        case features::DanglingPtrType::kCrossTask:
          partition_alloc::SetDanglingRawPtrReleasedFn(
              &DanglingRawPtrReleased<features::DanglingPtrMode::kLogOnly,
                                      features::DanglingPtrType::kCrossTask>);
          break;
      }
      break;
  }
}

// TODO(arthursonzogni): There might exist long lived dangling raw_ptr. If there
// is a dangling pointer, we should crash at some point. Consider providing an
// API to periodically check the buffer.

#else   // PA_BUILDFLAG(ENABLE_DANGLING_RAW_PTR_CHECKS)
void InstallDanglingRawPtrChecks() {}
#endif  // PA_BUILDFLAG(ENABLE_DANGLING_RAW_PTR_CHECKS)

void UnretainedDanglingRawPtrDetectedDumpWithoutCrashing(uintptr_t id) {
  PA_NO_CODE_FOLDING();
  debug::DumpWithoutCrashing();
}

void UnretainedDanglingRawPtrDetectedCrash(uintptr_t id) {
  static const char unretained_dangling_ptr_footer[] =
      "\n"
      "\n"
      "Please check for more information on:\n"
      "https://chromium.googlesource.com/chromium/src/+/main/docs/"
      "unretained_dangling_ptr_guide.md\n";
  debug::TaskTrace task_trace;
  debug::StackTrace stack_trace;
  LOG(FATAL) << "Detected dangling raw_ptr in unretained with id="
             << StringPrintf("0x%016" PRIxPTR, id) << ":\n\n"
             << task_trace << '\n'
             << "Stack trace:\n"
             << stack_trace << unretained_dangling_ptr_footer;
}

void InstallUnretainedDanglingRawPtrChecks() {
  if (!FeatureList::IsEnabled(features::kPartitionAllocUnretainedDanglingPtr)) {
    partition_alloc::SetUnretainedDanglingRawPtrDetectedFn([](uintptr_t) {});
    partition_alloc::SetUnretainedDanglingRawPtrCheckEnabled(/*enabled=*/false);
    return;
  }

  partition_alloc::SetUnretainedDanglingRawPtrCheckEnabled(/*enabled=*/true);
  switch (features::kUnretainedDanglingPtrModeParam.Get()) {
    case features::UnretainedDanglingPtrMode::kCrash:
      partition_alloc::SetUnretainedDanglingRawPtrDetectedFn(
          &UnretainedDanglingRawPtrDetectedCrash);
      break;

    case features::UnretainedDanglingPtrMode::kDumpWithoutCrashing:
      partition_alloc::SetUnretainedDanglingRawPtrDetectedFn(
          &UnretainedDanglingRawPtrDetectedDumpWithoutCrashing);
      break;
  }
}

void ReconfigurePartitionForKnownProcess(const std::string& process_type) {
  DCHECK_NE(process_type, switches::kZygoteProcess);
  // TODO(keishi): Move the code to enable BRP back here after Finch
  // experiments.
}

void MakeFreeNoOp() {
  // Ignoring `free()` during Shutdown would allow developers to introduce new
  // dangling pointers. So we want to avoid ignoring free when it is enabled.
  // Note: For now, the DanglingPointerDetector is only enabled on 5 bots, and
  // on linux non-official configuration.
#if PA_BUILDFLAG(ENABLE_DANGLING_RAW_PTR_CHECKS)
  CHECK(base::FeatureList::GetInstance());
  if (base::FeatureList::IsEnabled(features::kPartitionAllocDanglingPtr)) {
    return;
  }
#endif  // PA_BUILDFLAG(ENABLE_DANGLING_RAW_PTR_CHECKS)
#if PA_BUILDFLAG(USE_ALLOCATOR_SHIM)
  allocator_shim::InsertNoOpOnFreeAllocatorShimOnShutDown();
#endif  // PA_BUILDFLAG(USE_ALLOCATOR_SHIM)
}

PartitionAllocSupport* PartitionAllocSupport::Get() {
  static auto* singleton = new PartitionAllocSupport();
  return singleton;
}

PartitionAllocSupport::PartitionAllocSupport() = default;

void PartitionAllocSupport::ReconfigureForTests() {
  ReconfigureEarlyish("");
  base::AutoLock scoped_lock(lock_);
  called_for_tests_ = true;
}

// static
bool PartitionAllocSupport::ShouldEnableMemoryTagging(
    const std::string& process_type) {
  // Check kPartitionAllocMemoryTagging first so the Feature is activated even
  // when mte bootloader flag is disabled.
  if (!base::FeatureList::IsEnabled(
          base::features::kPartitionAllocMemoryTagging)) {
    return false;
  }
  if (!base::CPU::GetInstanceNoAllocation().has_mte()) {
    return false;
  }

  DCHECK(base::FeatureList::GetInstance());
  if (base::FeatureList::IsEnabled(
          base::features::kKillPartitionAllocMemoryTagging)) {
    return false;
  }
  return ShouldEnableFeatureOnProcess(
      base::features::kMemoryTaggingEnabledProcessesParam.Get(), process_type);
}

// static
bool PartitionAllocSupport::ShouldEnableMemoryTaggingInRendererProcess() {
  return ShouldEnableMemoryTagging(switches::kRendererProcess);
}

// static
bool PartitionAllocSupport::ShouldEnablePartitionAllocWithAdvancedChecks(
    const std::string& process_type) {
#if !PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
  return false;
#else
  if (!base::FeatureList::IsEnabled(
          base::features::kPartitionAllocWithAdvancedChecks)) {
    return false;
  }
  return ShouldEnableFeatureOnProcess(
      base::features::kPartitionAllocWithAdvancedChecksEnabledProcessesParam
          .Get(),
      process_type);
#endif  // !PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
}

// static
PartitionAllocSupport::BrpConfiguration
PartitionAllocSupport::GetBrpConfiguration(const std::string& process_type) {
  // TODO(bartekn): Switch to DCHECK once confirmed there are no issues.
  CHECK(base::FeatureList::GetInstance());

#if PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC) && \
    PA_BUILDFLAG(ENABLE_BACKUP_REF_PTR_SUPPORT) && \
    !PA_BUILDFLAG(FORCE_DISABLE_BACKUP_REF_PTR_FEATURE)

  if (base::FeatureList::IsEnabled(
          base::features::kPartitionAllocBackupRefPtr) &&
      base::features::kBackupRefPtrModeParam.Get() !=
          base::features::BackupRefPtrMode::kDisabled &&
      ShouldEnableFeatureOnProcess(
          base::features::kBackupRefPtrEnabledProcessesParam.Get(),
          process_type)) {
    return {
        .enable_brp = true,
        .extra_extras_size = static_cast<size_t>(
            base::features::kBackupRefPtrExtraExtrasSizeParam.Get()),
    };
  }
#endif

  return {
      .enable_brp = false,
      .extra_extras_size = 0,
  };
}

void PartitionAllocSupport::ReconfigureEarlyish(
    const std::string& process_type) {
  {
    base::AutoLock scoped_lock(lock_);

    // In tests, ReconfigureEarlyish() is called by ReconfigureForTest(), which
    // is earlier than ContentMain().
    if (called_for_tests_) {
      DCHECK(called_earlyish_);
      return;
    }

    // TODO(bartekn): Switch to DCHECK once confirmed there are no issues.
    CHECK(!called_earlyish_)
        << "ReconfigureEarlyish was already called for process '"
        << established_process_type_ << "'; current process: '" << process_type
        << "'";

    called_earlyish_ = true;
    established_process_type_ = process_type;
  }

  if (process_type != switches::kZygoteProcess) {
    ReconfigurePartitionForKnownProcess(process_type);
  }

  // These initializations are only relevant for PartitionAlloc-Everywhere
  // builds.
#if PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
  allocator_shim::EnablePartitionAllocMemoryReclaimer();
#endif  // PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
}

void PartitionAllocSupport::ReconfigureAfterZygoteFork(
    const std::string& process_type) {
  {
    base::AutoLock scoped_lock(lock_);
    // TODO(bartekn): Switch to DCHECK once confirmed there are no issues.
    CHECK(!called_after_zygote_fork_)
        << "ReconfigureAfterZygoteFork was already called for process '"
        << established_process_type_ << "'; current process: '" << process_type
        << "'";
    DCHECK(called_earlyish_)
        << "Attempt to call ReconfigureAfterZygoteFork without calling "
           "ReconfigureEarlyish; current process: '"
        << process_type << "'";
    DCHECK_EQ(established_process_type_, switches::kZygoteProcess)
        << "Attempt to call ReconfigureAfterZygoteFork while "
           "ReconfigureEarlyish was called on non-zygote process '"
        << established_process_type_ << "'; current process: '" << process_type
        << "'";

    called_after_zygote_fork_ = true;
    established_process_type_ = process_type;
  }

  if (process_type != switches::kZygoteProcess) {
    ReconfigurePartitionForKnownProcess(process_type);
  }
}

void PartitionAllocSupport::ReconfigureAfterFeatureListInit(
    const std::string& process_type,
    bool configure_dangling_pointer_detector) {
  if (configure_dangling_pointer_detector) {
    base::allocator::InstallDanglingRawPtrChecks();
  }
  base::allocator::InstallUnretainedDanglingRawPtrChecks();
  {
    base::AutoLock scoped_lock(lock_);
    // Avoid initializing more than once.
    if (called_after_feature_list_init_) {
      DCHECK_EQ(established_process_type_, process_type)
          << "ReconfigureAfterFeatureListInit was already called for process '"
          << established_process_type_ << "'; current process: '"
          << process_type << "'";
      return;
    }
    DCHECK(called_earlyish_)
        << "Attempt to call ReconfigureAfterFeatureListInit without calling "
           "ReconfigureEarlyish; current process: '"
        << process_type << "'";
    DCHECK_NE(established_process_type_, switches::kZygoteProcess)
        << "Attempt to call ReconfigureAfterFeatureListInit without calling "
           "ReconfigureAfterZygoteFork; current process: '"
        << process_type << "'";
    DCHECK_EQ(established_process_type_, process_type)
        << "ReconfigureAfterFeatureListInit wasn't called for an already "
           "established process '"
        << established_process_type_ << "'; current process: '" << process_type
        << "'";

    called_after_feature_list_init_ = true;
  }

  DCHECK_NE(process_type, switches::kZygoteProcess);
  [[maybe_unused]] BrpConfiguration brp_config =
      GetBrpConfiguration(process_type);

  // Configure ASAN hooks to report the `MiraclePtr status`. This is enabled
  // only if BackupRefPtr is normally enabled in the current process for the
  // current platform. Note that CastOS and iOS aren't protected by BackupRefPtr
  // a the moment, so they are excluded.
#if PA_BUILDFLAG(USE_ASAN_BACKUP_REF_PTR) && !PA_BUILDFLAG(IS_CASTOS) && \
    !PA_BUILDFLAG(IS_IOS)
  if (ShouldEnableFeatureOnProcess(
          base::features::kBackupRefPtrEnabledProcessesParam.Get(),
          process_type)) {
    base::RawPtrAsanService::GetInstance().Configure(
        base::EnableDereferenceCheck(
            base::features::kBackupRefPtrAsanEnableDereferenceCheckParam.Get()),
        base::EnableExtractionCheck(
            base::features::kBackupRefPtrAsanEnableExtractionCheckParam.Get()),
        base::EnableInstantiationCheck(
            base::features::kBackupRefPtrAsanEnableInstantiationCheckParam
                .Get()));
  } else {
    base::RawPtrAsanService::GetInstance().Configure(
        base::EnableDereferenceCheck(false), base::EnableExtractionCheck(false),
        base::EnableInstantiationCheck(false));
  }
#endif  // PA_BUILDFLAG(USE_ASAN_BACKUP_REF_PTR)

#if PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
  auto bucket_distribution = allocator_shim::BucketDistribution::kNeutral;
  // No specified type means we are in the browser.
  switch (process_type == ""
              ? base::features::kPartitionAllocBucketDistributionParam.Get()
              : base::features::BucketDistributionMode::kDefault) {
    case base::features::BucketDistributionMode::kDefault:
      break;
    case base::features::BucketDistributionMode::kDenser:
      bucket_distribution = allocator_shim::BucketDistribution::kDenser;
      break;
  }

  const bool scheduler_loop_quarantine = base::FeatureList::IsEnabled(
      base::features::kPartitionAllocSchedulerLoopQuarantine);
  const size_t scheduler_loop_quarantine_branch_capacity_in_bytes =
      static_cast<size_t>(
          base::features::kPartitionAllocSchedulerLoopQuarantineBranchCapacity
              .Get());
  const bool zapping_by_free_flags = base::FeatureList::IsEnabled(
      base::features::kPartitionAllocZappingByFreeFlags);
  const bool eventually_zero_freed_memory = base::FeatureList::IsEnabled(
      base::features::kPartitionAllocEventuallyZeroFreedMemory);
  const bool fewer_memory_regions = base::FeatureList::IsEnabled(
      base::features::kPartitionAllocFewerMemoryRegions);

#if PA_BUILDFLAG(USE_FREELIST_DISPATCHER)
  const bool use_pool_offset_freelists =
      base::FeatureList::IsEnabled(base::features::kUsePoolOffsetFreelists);
#else
  const bool use_pool_offset_freelists = false;
#endif  // PA_BUILDFLAG(USE_FREELIST_DISPATCHER)

  bool enable_memory_tagging = false;
  partition_alloc::TagViolationReportingMode memory_tagging_reporting_mode =
      partition_alloc::TagViolationReportingMode::kUndefined;

#if PA_BUILDFLAG(HAS_MEMORY_TAGGING)
  // ShouldEnableMemoryTagging() checks kKillPartitionAllocMemoryTagging but
  // check here too to wrap the GetMemoryTaggingModeForCurrentThread() call.
  if (!base::FeatureList::IsEnabled(
          base::features::kKillPartitionAllocMemoryTagging)) {
    // If synchronous mode is enabled from startup it means this is a test or it
    // was force enabled in Chrome some how so honor that choice.
    partition_alloc::TagViolationReportingMode
        startup_memory_tagging_reporting_mode =
            partition_alloc::internal::GetMemoryTaggingModeForCurrentThread();
    if (startup_memory_tagging_reporting_mode ==
        partition_alloc::TagViolationReportingMode::kSynchronous) {
      enable_memory_tagging = true;
      memory_tagging_reporting_mode =
          partition_alloc::TagViolationReportingMode::kSynchronous;
      // Not enabling permissive mode as this config is used to crash and detect
      // bugs.
      VLOG(1) << "PartitionAlloc: Memory tagging enabled in SYNC mode at "
                 "startup (Process: "
              << process_type << ")";
    } else {
      enable_memory_tagging = ShouldEnableMemoryTagging(process_type);
#if BUILDFLAG(IS_ANDROID)
      // Android Scudo does not allow MTE to be re-enabled if MTE was disabled.
      if (enable_memory_tagging &&
          startup_memory_tagging_reporting_mode ==
              partition_alloc::TagViolationReportingMode::kDisabled) {
        LOG(ERROR) << "PartitionAlloc: Failed to enable memory tagging due to "
                      "MTE disabled at startup (Process: "
                   << process_type << ")";
        debug::DumpWithoutCrashing();
        enable_memory_tagging = false;
      }

      if (enable_memory_tagging) {
        // Configure MTE.
        switch (base::features::kMemtagModeParam.Get()) {
          case base::features::MemtagMode::kSync:
            memory_tagging_reporting_mode =
                partition_alloc::TagViolationReportingMode::kSynchronous;
            break;
          case base::features::MemtagMode::kAsync:
            memory_tagging_reporting_mode =
                partition_alloc::TagViolationReportingMode::kAsynchronous;
            break;
        }
        bool enable_permissive_mte = base::FeatureList::IsEnabled(
            base::features::kPartitionAllocPermissiveMte);
        partition_alloc::PermissiveMte::SetEnabled(enable_permissive_mte);
        CHECK(partition_alloc::internal::
                  ChangeMemoryTaggingModeForAllThreadsPerProcess(
                      memory_tagging_reporting_mode));
        CHECK_EQ(
            partition_alloc::internal::GetMemoryTaggingModeForCurrentThread(),
            memory_tagging_reporting_mode);
        VLOG(1)
            << "PartitionAlloc: Memory tagging enabled in "
            << (memory_tagging_reporting_mode ==
                        partition_alloc::TagViolationReportingMode::kSynchronous
                    ? "SYNC"
                    : "ASYNC")
            << " mode (Process: " << process_type << ")";
        if (enable_permissive_mte) {
          VLOG(1) << "PartitionAlloc: Permissive MTE enabled (Process: "
                  << process_type << ")";
        }
      } else if (base::CPU::GetInstanceNoAllocation().has_mte()) {
        // Disable MTE.
        memory_tagging_reporting_mode =
            partition_alloc::TagViolationReportingMode::kDisabled;
        CHECK(partition_alloc::internal::
                  ChangeMemoryTaggingModeForAllThreadsPerProcess(
                      memory_tagging_reporting_mode));
        CHECK_EQ(
            partition_alloc::internal::GetMemoryTaggingModeForCurrentThread(),
            memory_tagging_reporting_mode);
        VLOG(1) << "PartitionAlloc: Memory tagging disabled (Process: "
                << process_type << ")";
      }
#endif  // BUILDFLAG(IS_ANDROID)
    }
  }
#endif  // PA_BUILDFLAG(HAS_MEMORY_TAGGING)

  allocator_shim::UseSmallSingleSlotSpans use_small_single_slot_spans(
      base::FeatureList::IsEnabled(
          features::kPartitionAllocUseSmallSingleSlotSpans));

  allocator_shim::ConfigurePartitions(
      allocator_shim::EnableBrp(brp_config.enable_brp),
      brp_config.extra_extras_size,
      allocator_shim::EnableMemoryTagging(enable_memory_tagging),
      memory_tagging_reporting_mode, bucket_distribution,
      allocator_shim::SchedulerLoopQuarantine(scheduler_loop_quarantine),
      scheduler_loop_quarantine_branch_capacity_in_bytes,
      allocator_shim::ZappingByFreeFlags(zapping_by_free_flags),
      allocator_shim::EventuallyZeroFreedMemory(eventually_zero_freed_memory),
      allocator_shim::FewerMemoryRegions(fewer_memory_regions),
      allocator_shim::UsePoolOffsetFreelists(use_pool_offset_freelists),
      use_small_single_slot_spans);

  const uint32_t extras_size = allocator_shim::GetMainPartitionRootExtrasSize();
  // As per description, extras are optional and are expected not to
  // exceed (cookie + max(BRP ref-count)) == 16 + 16 == 32 bytes.
  // 100 is a reasonable cap for this value.
  UmaHistogramCounts100("Memory.PartitionAlloc.PartitionRoot.ExtrasSize",
                        int(extras_size));

#if !defined(__MUSL__)
  // This call causes hanging in pthread_getattr_np() under qemu-user, see
  // https://www.openwall.com/lists/musl/2017/06/15/9.
  partition_alloc::internal::StackTopRegistry::Get().NotifyThreadCreated(
      partition_alloc::internal::GetStackTop());
#endif

  allocator_shim::internal::PartitionAllocMalloc::Allocator()
      ->EnableThreadCacheIfSupported();

  if (base::FeatureList::IsEnabled(
          base::features::kPartitionAllocLargeEmptySlotSpanRing)) {
    allocator_shim::internal::PartitionAllocMalloc::Allocator()
        ->EnableLargeEmptySlotSpanRing();
  }

  if (process_type == "" &&
      base::FeatureList::IsEnabled(
          base::features::kPartitionAllocSchedulerLoopQuarantine)) {
    // `ReconfigureAfterTaskRunnerInit()` is called on the UI thread.
    const size_t capacity_in_bytes = static_cast<size_t>(
        base::features::kPartitionAllocSchedulerLoopQuarantineBrowserUICapacity
            .Get());
    allocator_shim::internal::PartitionAllocMalloc::Allocator()
        ->SetSchedulerLoopQuarantineThreadLocalBranchCapacity(
            capacity_in_bytes);
  }

#if PA_BUILDFLAG( \
    ENABLE_ALLOCATOR_SHIM_PARTITION_ALLOC_DISPATCH_WITH_ADVANCED_CHECKS_SUPPORT)
  bool enable_pa_with_advanced_checks =
      ShouldEnablePartitionAllocWithAdvancedChecks(process_type);
  if (enable_pa_with_advanced_checks) {
    allocator_shim::InstallCustomDispatchForPartitionAllocWithAdvancedChecks();
  }
#endif  // PA_BUILDFLAG(
        // ENABLE_ALLOCATOR_SHIM_PARTITION_ALLOC_DISPATCH_WITH_ADVANCED_CHECKS_SUPPORT)
#endif  // PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)

#if BUILDFLAG(IS_WIN)
  // Browser process only, since this is the one we want to prevent from
  // crashing the most (as it takes down all the tabs).
  if (base::FeatureList::IsEnabled(
          base::features::kPageAllocatorRetryOnCommitFailure) &&
      process_type.empty()) {
    partition_alloc::SetRetryOnCommitFailure(true);
  }
#endif
}

void PartitionAllocSupport::ReconfigureAfterTaskRunnerInit(
    const std::string& process_type) {
  {
    base::AutoLock scoped_lock(lock_);

    // Init only once.
    if (called_after_thread_pool_init_) {
      return;
    }

    DCHECK_EQ(established_process_type_, process_type);
    // Enforce ordering.
    DCHECK(called_earlyish_);
    DCHECK(called_after_feature_list_init_);

    called_after_thread_pool_init_ = true;
  }

#if PA_CONFIG(THREAD_CACHE_SUPPORTED) && \
    PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
  // This should be called in specific processes, as the main thread is
  // initialized later.
  DCHECK(process_type != switches::kZygoteProcess);

  partition_alloc::ThreadCacheRegistry::Instance().SetPurgingConfiguration(
      base::features::GetThreadCacheMinPurgeInterval(),
      base::features::GetThreadCacheMaxPurgeInterval(),
      base::features::GetThreadCacheDefaultPurgeInterval(),
      size_t(base::features::GetThreadCacheMinCachedMemoryForPurgingBytes()));

  base::allocator::StartThreadCachePeriodicPurge();

  if (base::FeatureList::IsEnabled(
          base::features::kEnableConfigurableThreadCacheMultiplier)) {
    // If kEnableConfigurableThreadCacheMultiplier is enabled, override the
    // multiplier value with the corresponding feature param.
#if BUILDFLAG(IS_ANDROID)
    ::partition_alloc::ThreadCacheRegistry::Instance().SetThreadCacheMultiplier(
        base::features::GetThreadCacheMultiplierForAndroid());
#else   // BUILDFLAG(IS_ANDROID)
    ::partition_alloc::ThreadCacheRegistry::Instance().SetThreadCacheMultiplier(
        base::features::GetThreadCacheMultiplier());
#endif  // BUILDFLAG(IS_ANDROID)
  } else {
#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_CHROMEOS)
    // If kEnableConfigurableThreadCacheMultiplier is not enabled, lower
    // thread cache limits on Android low end device to avoid stranding too much
    // memory in the caches.
    if (SysInfo::IsLowEndDeviceOrPartialLowEndModeEnabled(
            features::kPartialLowEndModeExcludePartitionAllocSupport)) {
      ::partition_alloc::ThreadCacheRegistry::Instance()
          .SetThreadCacheMultiplier(
              ::partition_alloc::ThreadCache::kDefaultMultiplier / 2.);
    }
#endif  // BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_CHROMEOS)
  }

  // Renderer processes are more performance-sensitive, increase thread cache
  // limits.
  if (process_type == switches::kRendererProcess &&
      base::FeatureList::IsEnabled(
          base::features::kPartitionAllocLargeThreadCacheSize)) {
    largest_cached_size_ =
        size_t(base::features::GetPartitionAllocLargeThreadCacheSizeValue());

#if BUILDFLAG(IS_ANDROID)
    // Use appropriately lower amount for Android devices with 3GB or less.
    // Devices almost always report less physical memory than what they actually
    // have, so use 3.2GB (a threshold commonly uses throughout code) to avoid
    // accidentally catching devices advertised as 4GB.
    if (base::SysInfo::AmountOfPhysicalMemoryMB() < 3.2 * 1024) {
      largest_cached_size_ = size_t(
          base::features::
              GetPartitionAllocLargeThreadCacheSizeValueForLowRAMAndroid());
    }
#endif  // BUILDFLAG(IS_ANDROID)

    ::partition_alloc::ThreadCache::SetLargestCachedSize(largest_cached_size_);
  }
#endif  // PA_CONFIG(THREAD_CACHE_SUPPORTED) &&
        // PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)

#if PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
  base::allocator::StartMemoryReclaimer(
      base::SingleThreadTaskRunner::GetCurrentDefault());
#endif

  partition_alloc::PartitionRoot::SetStraightenLargerSlotSpanFreeListsMode(
      base::FeatureList::IsEnabled(
          base::features::kPartitionAllocStraightenLargerSlotSpanFreeLists)
          ? features::kPartitionAllocStraightenLargerSlotSpanFreeListsMode.Get()
          : partition_alloc::StraightenLargerSlotSpanFreeListsMode::kNever);
  partition_alloc::PartitionRoot::SetSortSmallerSlotSpanFreeListsEnabled(
      base::FeatureList::IsEnabled(
          base::features::kPartitionAllocSortSmallerSlotSpanFreeLists));
  partition_alloc::PartitionRoot::SetSortActiveSlotSpansEnabled(
      base::FeatureList::IsEnabled(
          base::features::kPartitionAllocSortActiveSlotSpans));

#if PA_CONFIG(ENABLE_SHADOW_METADATA)
  if (ShouldEnableShadowMetadata(process_type)) {
    partition_alloc::PartitionRoot::EnableShadowMetadata(
        partition_alloc::internal::PoolHandleMask::kRegular |
        partition_alloc::internal::PoolHandleMask::kBRP |
        partition_alloc::internal::PoolHandleMask::kConfigurable);
  }
#endif  // PA_CONFIG(ENABLE_SHADOW_METADATA)
}

void PartitionAllocSupport::OnForegrounded(bool has_main_frame) {
#if PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
  // Other changes are renderer-only, not this one.
  MemoryReclaimerSupport::Instance().SetForegrounded(true);

  {
    base::AutoLock scoped_lock(lock_);
    if (established_process_type_ != switches::kRendererProcess) {
      return;
    }
  }
#if PA_CONFIG(THREAD_CACHE_SUPPORTED)
  if (!base::FeatureList::IsEnabled(
          features::kLowerPAMemoryLimitForNonMainRenderers) ||
      has_main_frame) {
    ::partition_alloc::ThreadCache::SetLargestCachedSize(largest_cached_size_);
  }
#endif  // PA_CONFIG(THREAD_CACHE_SUPPORTED)
  if (base::FeatureList::IsEnabled(
          features::kPartitionAllocAdjustSizeWhenInForeground)) {
    allocator_shim::AdjustDefaultAllocatorForForeground();
  }
#endif  // PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
}

void PartitionAllocSupport::OnBackgrounded() {
#if PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
  // Other changes are renderer-only, not this one.
  MemoryReclaimerSupport::Instance().SetForegrounded(false);

  {
    base::AutoLock scoped_lock(lock_);
    if (established_process_type_ != switches::kRendererProcess) {
      return;
    }
  }
#if PA_CONFIG(THREAD_CACHE_SUPPORTED)
  // Performance matters less for background renderers, don't pay the memory
  // cost.
  ::partition_alloc::ThreadCache::SetLargestCachedSize(
      ::partition_alloc::kThreadCacheDefaultSizeThreshold);

  // In renderers, memory reclaim uses the "idle time" task runner to run
  // periodic reclaim. This does not always run when the renderer is idle, and
  // in particular after the renderer gets backgrounded. As a result, empty slot
  // spans are potentially never decommitted. To mitigate that, run a one-off
  // reclaim a few seconds later. Even if the renderer comes back to foreground
  // in the meantime, the worst case is a few more system calls.
  //
  // TODO(lizeb): Remove once/if the behavior of idle tasks changes.
  base::PostDelayedMemoryReductionTask(
      base::SingleThreadTaskRunner::GetCurrentDefault(), FROM_HERE,
      base::BindOnce(
          [] { ::partition_alloc::MemoryReclaimer::Instance()->ReclaimAll(); }),
      base::Seconds(10));

#endif  // PA_CONFIG(THREAD_CACHE_SUPPORTED)
  if (base::FeatureList::IsEnabled(
          features::kPartitionAllocAdjustSizeWhenInForeground)) {
    allocator_shim::AdjustDefaultAllocatorForBackground();
  }
#endif  // PA_BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
}

#if PA_BUILDFLAG(ENABLE_DANGLING_RAW_PTR_CHECKS)
std::string PartitionAllocSupport::ExtractDanglingPtrSignatureForTests(
    std::string stacktrace) {
  return ExtractDanglingPtrSignature(stacktrace);
}
#endif

}  // namespace base::allocator