diff --git a/debuggerd/Android.bp b/debuggerd/Android.bp
index 15b5813..5da1b40 100644
--- a/debuggerd/Android.bp
+++ b/debuggerd/Android.bp
@@ -98,6 +98,7 @@
         "libbase_headers",
         "libdebuggerd_common_headers",
         "bionic_libc_platform_headers",
+        "gwp_asan_headers",
     ],
 
     whole_static_libs: [
diff --git a/debuggerd/crash_dump.cpp b/debuggerd/crash_dump.cpp
index 70f333e..cbb1181 100644
--- a/debuggerd/crash_dump.cpp
+++ b/debuggerd/crash_dump.cpp
@@ -265,10 +265,12 @@
 }
 
 static void ReadCrashInfo(unique_fd& fd, siginfo_t* siginfo,
-                          std::unique_ptr<unwindstack::Regs>* regs, ProcessInfo* process_info) {
+                          std::unique_ptr<unwindstack::Regs>* regs, ProcessInfo* process_info,
+                          bool* recoverable_gwp_asan_crash) {
   std::aligned_storage<sizeof(CrashInfo) + 1, alignof(CrashInfo)>::type buf;
   CrashInfo* crash_info = reinterpret_cast<CrashInfo*>(&buf);
   ssize_t rc = TEMP_FAILURE_RETRY(read(fd.get(), &buf, sizeof(buf)));
+  *recoverable_gwp_asan_crash = false;
   if (rc == -1) {
     PLOG(FATAL) << "failed to read target ucontext";
   } else {
@@ -304,6 +306,7 @@
       process_info->scudo_region_info = crash_info->data.d.scudo_region_info;
       process_info->scudo_ring_buffer = crash_info->data.d.scudo_ring_buffer;
       process_info->scudo_ring_buffer_size = crash_info->data.d.scudo_ring_buffer_size;
+      *recoverable_gwp_asan_crash = crash_info->data.d.recoverable_gwp_asan_crash;
       FALLTHROUGH_INTENDED;
     case 1:
     case 2:
@@ -468,6 +471,7 @@
   std::map<pid_t, ThreadInfo> thread_info;
   siginfo_t siginfo;
   std::string error;
+  bool recoverable_gwp_asan_crash = false;
 
   {
     ATRACE_NAME("ptrace");
@@ -519,7 +523,8 @@
 
       if (thread == g_target_thread) {
         // Read the thread's registers along with the rest of the crash info out of the pipe.
-        ReadCrashInfo(input_pipe, &siginfo, &info.registers, &process_info);
+        ReadCrashInfo(input_pipe, &siginfo, &info.registers, &process_info,
+                      &recoverable_gwp_asan_crash);
         info.siginfo = &siginfo;
         info.signo = info.siginfo->si_signo;
 
@@ -646,7 +651,7 @@
     }
   }
 
-  if (fatal_signal) {
+  if (fatal_signal && !recoverable_gwp_asan_crash) {
     // Don't try to notify ActivityManager if it just crashed, or we might hang until timeout.
     if (thread_info[target_process].thread_name != "system_server") {
       activity_manager_notify(target_process, signo, amfd_data);
diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index 9c1b136..895c111 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -36,6 +36,7 @@
 #include <string>
 #include <thread>
 
+#include <android/dlext.h>
 #include <android/fdsan.h>
 #include <android/set_abort_message.h>
 #include <bionic/malloc.h>
@@ -64,6 +65,7 @@
 
 #include "crash_test.h"
 #include "debuggerd/handler.h"
+#include "gtest/gtest.h"
 #include "libdebuggerd/utility.h"
 #include "protocol.h"
 #include "tombstoned/tombstoned.h"
@@ -110,19 +112,6 @@
   ASSERT_MATCH(result,                             \
                R"(#\d\d pc [0-9a-f]+\s+ \S+ (\(offset 0x[0-9a-f]+\) )?\()" frame_name R"(\+)");
 
-// Enable GWP-ASan at the start of this process. GWP-ASan is enabled using
-// process sampling, so we need to ensure we force GWP-ASan on.
-__attribute__((constructor)) static void enable_gwp_asan() {
-  android_mallopt_gwp_asan_options_t opts;
-  // No, we're not an app, but let's turn ourselves on without sampling.
-  // Technically, if someone's using the *.default_app sysprops, they'll adjust
-  // our settings, but I don't think this will be common on a device that's
-  // running debuggerd_tests.
-  opts.desire = android_mallopt_gwp_asan_options_t::Action::TURN_ON_FOR_APP;
-  opts.program_name = "";
-  android_mallopt(M_INITIALIZE_GWP_ASAN, &opts, sizeof(android_mallopt_gwp_asan_options_t));
-}
-
 static void tombstoned_intercept(pid_t target_pid, unique_fd* intercept_fd, unique_fd* output_fd,
                                  InterceptStatus* status, DebuggerdDumpType intercept_type) {
   intercept_fd->reset(socket_local_client(kTombstonedInterceptSocketName,
@@ -468,76 +457,6 @@
 }
 #endif
 
-// Number of iterations required to reliably guarantee a GWP-ASan crash.
-// GWP-ASan's sample rate is not truly nondeterministic, it initialises a
-// thread-local counter at 2*SampleRate, and decrements on each malloc(). Once
-// the counter reaches zero, we provide a sampled allocation. Then, double that
-// figure to allow for left/right allocation alignment, as this is done randomly
-// without bias.
-#define GWP_ASAN_ITERATIONS_TO_ENSURE_CRASH (0x20000)
-
-struct GwpAsanTestParameters {
-  size_t alloc_size;
-  bool free_before_access;
-  int access_offset;
-  std::string cause_needle; // Needle to be found in the "Cause: [GWP-ASan]" line.
-};
-
-struct GwpAsanCrasherTest : CrasherTest, testing::WithParamInterface<GwpAsanTestParameters> {};
-
-GwpAsanTestParameters gwp_asan_tests[] = {
-  {/* alloc_size */ 7, /* free_before_access */ true, /* access_offset */ 0, "Use After Free, 0 bytes into a 7-byte allocation"},
-  {/* alloc_size */ 7, /* free_before_access */ true, /* access_offset */ 1, "Use After Free, 1 byte into a 7-byte allocation"},
-  {/* alloc_size */ 7, /* free_before_access */ false, /* access_offset */ 16, "Buffer Overflow, 9 bytes right of a 7-byte allocation"},
-  {/* alloc_size */ 16, /* free_before_access */ false, /* access_offset */ -1, "Buffer Underflow, 1 byte left of a 16-byte allocation"},
-};
-
-INSTANTIATE_TEST_SUITE_P(GwpAsanTests, GwpAsanCrasherTest, testing::ValuesIn(gwp_asan_tests));
-
-TEST_P(GwpAsanCrasherTest, gwp_asan_uaf) {
-  if (mte_supported()) {
-    // Skip this test on MTE hardware, as MTE will reliably catch these errors
-    // instead of GWP-ASan.
-    GTEST_SKIP() << "Skipped on MTE.";
-  }
-  // Skip this test on HWASan, which will reliably catch test errors as well.
-  SKIP_WITH_HWASAN;
-
-  GwpAsanTestParameters params = GetParam();
-  LogcatCollector logcat_collector;
-
-  int intercept_result;
-  unique_fd output_fd;
-  StartProcess([&params]() {
-    for (unsigned i = 0; i < GWP_ASAN_ITERATIONS_TO_ENSURE_CRASH; ++i) {
-      volatile char* p = reinterpret_cast<volatile char*>(malloc(params.alloc_size));
-      if (params.free_before_access) free(static_cast<void*>(const_cast<char*>(p)));
-      p[params.access_offset] = 42;
-      if (!params.free_before_access) free(static_cast<void*>(const_cast<char*>(p)));
-    }
-  });
-
-  StartIntercept(&output_fd);
-  FinishCrasher();
-  AssertDeath(SIGSEGV);
-  FinishIntercept(&intercept_result);
-
-  ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
-
-  std::vector<std::string> log_sources(2);
-  ConsumeFd(std::move(output_fd), &log_sources[0]);
-  logcat_collector.Collect(&log_sources[1]);
-
-  for (const auto& result : log_sources) {
-    ASSERT_MATCH(result, R"(signal 11 \(SIGSEGV\), code 2 \(SEGV_ACCERR\))");
-    ASSERT_MATCH(result, R"(Cause: \[GWP-ASan\]: )" + params.cause_needle);
-    if (params.free_before_access) {
-      ASSERT_MATCH(result, R"(deallocated by thread .*\n.*#00 pc)");
-    }
-    ASSERT_MATCH(result, R"((^|\s)allocated by thread .*\n.*#00 pc)");
-  }
-}
-
 struct SizeParamCrasherTest : CrasherTest, testing::WithParamInterface<size_t> {};
 
 INSTANTIATE_TEST_SUITE_P(Sizes, SizeParamCrasherTest, testing::Values(0, 16, 131072));
@@ -1278,7 +1197,11 @@
 static const char* const kDebuggerdSeccompPolicy =
     "/system/etc/seccomp_policy/crash_dump." ABI_STRING ".policy";
 
-static pid_t seccomp_fork_impl(void (*prejail)()) {
+static void setup_jail(minijail* jail) {
+  if (!jail) {
+    LOG(FATAL) << "failed to create minijail";
+  }
+
   std::string policy;
   if (!android::base::ReadFileToString(kDebuggerdSeccompPolicy, &policy)) {
     PLOG(FATAL) << "failed to read policy file";
@@ -1305,15 +1228,15 @@
     PLOG(FATAL) << "failed to seek tmp_fd";
   }
 
-  ScopedMinijail jail{minijail_new()};
-  if (!jail) {
-    LOG(FATAL) << "failed to create minijail";
-  }
+  minijail_no_new_privs(jail);
+  minijail_log_seccomp_filter_failures(jail);
+  minijail_use_seccomp_filter(jail);
+  minijail_parse_seccomp_filters_from_fd(jail, tmp_fd.release());
+}
 
-  minijail_no_new_privs(jail.get());
-  minijail_log_seccomp_filter_failures(jail.get());
-  minijail_use_seccomp_filter(jail.get());
-  minijail_parse_seccomp_filters_from_fd(jail.get(), tmp_fd.release());
+static pid_t seccomp_fork_impl(void (*prejail)()) {
+  ScopedMinijail jail{minijail_new()};
+  setup_jail(jail.get());
 
   pid_t result = fork();
   if (result == -1) {
@@ -1627,6 +1550,138 @@
   AssertDeath(SIGABRT);
 }
 
+struct GwpAsanTestParameters {
+  size_t alloc_size;
+  bool free_before_access;
+  int access_offset;
+  std::string cause_needle;  // Needle to be found in the "Cause: [GWP-ASan]" line.
+};
+
+struct GwpAsanCrasherTest
+    : CrasherTest,
+      testing::WithParamInterface<
+          std::tuple<GwpAsanTestParameters, /* recoverable */ bool, /* seccomp */ bool>> {};
+
+GwpAsanTestParameters gwp_asan_tests[] = {
+    {/* alloc_size */ 7, /* free_before_access */ true, /* access_offset */ 0,
+     "Use After Free, 0 bytes into a 7-byte allocation"},
+    {/* alloc_size */ 15, /* free_before_access */ true, /* access_offset */ 1,
+     "Use After Free, 1 byte into a 15-byte allocation"},
+    {/* alloc_size */ 4096, /* free_before_access */ false, /* access_offset */ 4098,
+     "Buffer Overflow, 2 bytes right of a 4096-byte allocation"},
+    {/* alloc_size */ 4096, /* free_before_access */ false, /* access_offset */ -1,
+     "Buffer Underflow, 1 byte left of a 4096-byte allocation"},
+};
+
+INSTANTIATE_TEST_SUITE_P(
+    GwpAsanTests, GwpAsanCrasherTest,
+    testing::Combine(testing::ValuesIn(gwp_asan_tests),
+                     /* recoverable */ testing::Bool(),
+                     /* seccomp */ testing::Bool()),
+    [](const testing::TestParamInfo<
+        std::tuple<GwpAsanTestParameters, /* recoverable */ bool, /* seccomp */ bool>>& info) {
+      const GwpAsanTestParameters& params = std::get<0>(info.param);
+      std::string name = params.free_before_access ? "UseAfterFree" : "Overflow";
+      name += testing::PrintToString(params.alloc_size);
+      name += "Alloc";
+      if (params.access_offset < 0) {
+        name += "Left";
+        name += testing::PrintToString(params.access_offset * -1);
+      } else {
+        name += "Right";
+        name += testing::PrintToString(params.access_offset);
+      }
+      name += "Bytes";
+      if (std::get<1>(info.param)) name += "Recoverable";
+      if (std::get<2>(info.param)) name += "Seccomp";
+      return name;
+    });
+
+TEST_P(GwpAsanCrasherTest, run_gwp_asan_test) {
+  if (mte_supported()) {
+    // Skip this test on MTE hardware, as MTE will reliably catch these errors
+    // instead of GWP-ASan.
+    GTEST_SKIP() << "Skipped on MTE.";
+  }
+  // Skip this test on HWASan, which will reliably catch test errors as well.
+  SKIP_WITH_HWASAN;
+
+  GwpAsanTestParameters params = std::get<0>(GetParam());
+  bool recoverable = std::get<1>(GetParam());
+  LogcatCollector logcat_collector;
+
+  int intercept_result;
+  unique_fd output_fd;
+  StartProcess([&recoverable]() {
+    const char* env[] = {"GWP_ASAN_SAMPLE_RATE=1", "GWP_ASAN_PROCESS_SAMPLING=1",
+                         "GWP_ASAN_MAX_ALLOCS=40000", nullptr, nullptr};
+    if (recoverable) {
+      env[3] = "GWP_ASAN_RECOVERABLE=true";
+    }
+    std::string test_name = ::testing::UnitTest::GetInstance()->current_test_info()->name();
+    test_name = std::regex_replace(test_name, std::regex("run_gwp_asan_test"),
+                                   "DISABLED_run_gwp_asan_test");
+    std::string test_filter = "--gtest_filter=*";
+    test_filter += test_name;
+    std::string this_binary = android::base::GetExecutablePath();
+    const char* args[] = {this_binary.c_str(), "--gtest_also_run_disabled_tests",
+                          test_filter.c_str(), nullptr};
+    // We check the crash report from a debuggerd handler and from logcat. The
+    // echo from stdout/stderr of the subprocess trips up atest, because it
+    // doesn't like that two tests started in a row without the first one
+    // finishing (even though the second one is in a subprocess).
+    close(STDOUT_FILENO);
+    close(STDERR_FILENO);
+    execve(this_binary.c_str(), const_cast<char**>(args), const_cast<char**>(env));
+  });
+
+  StartIntercept(&output_fd);
+  FinishCrasher();
+  if (recoverable) {
+    AssertDeath(0);
+  } else {
+    AssertDeath(SIGSEGV);
+  }
+  FinishIntercept(&intercept_result);
+
+  ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
+
+  std::vector<std::string> log_sources(2);
+  ConsumeFd(std::move(output_fd), &log_sources[0]);
+  logcat_collector.Collect(&log_sources[1]);
+
+  // seccomp forces the fallback handler, which doesn't print GWP-ASan debugging
+  // information. Make sure the recovery still works, but the report won't be
+  // hugely useful, it looks like a regular SEGV.
+  bool seccomp = std::get<2>(GetParam());
+  if (!seccomp) {
+    for (const auto& result : log_sources) {
+      ASSERT_MATCH(result, R"(signal 11 \(SIGSEGV\), code 2 \(SEGV_ACCERR\))");
+      ASSERT_MATCH(result, R"(Cause: \[GWP-ASan\]: )" + params.cause_needle);
+      if (params.free_before_access) {
+        ASSERT_MATCH(result, R"(deallocated by thread .*\n.*#00 pc)");
+      }
+      ASSERT_MATCH(result, R"((^|\s)allocated by thread .*\n.*#00 pc)");
+    }
+  }
+}
+
+TEST_P(GwpAsanCrasherTest, DISABLED_run_gwp_asan_test) {
+  GwpAsanTestParameters params = std::get<0>(GetParam());
+  bool seccomp = std::get<2>(GetParam());
+  if (seccomp) {
+    ScopedMinijail jail{minijail_new()};
+    setup_jail(jail.get());
+    minijail_enter(jail.get());
+  }
+
+  // Use 'volatile' to prevent a very clever compiler eliminating the store.
+  char* volatile p = reinterpret_cast<char* volatile>(malloc(params.alloc_size));
+  if (params.free_before_access) free(static_cast<void*>(const_cast<char*>(p)));
+  p[params.access_offset] = 42;
+  if (!params.free_before_access) free(static_cast<void*>(const_cast<char*>(p)));
+}
+
 TEST_F(CrasherTest, fdsan_warning_abort_message) {
   int intercept_result;
   unique_fd output_fd;
@@ -1909,7 +1964,7 @@
   ASSERT_MATCH(result, R"(Cause: stack pointer[^\n]*stack overflow.\n)");
 }
 
-static bool CopySharedLibrary(const char* tmp_dir, std::string* tmp_so_name) {
+static std::string GetTestLibraryPath() {
   std::string test_lib(testing::internal::GetArgvs()[0]);
   auto const value = test_lib.find_last_of('/');
   if (value == std::string::npos) {
@@ -1917,7 +1972,62 @@
   } else {
     test_lib = test_lib.substr(0, value + 1) + "./";
   }
-  test_lib += "libcrash_test.so";
+  return test_lib + "libcrash_test.so";
+}
+
+static void CreateEmbeddedLibrary(int out_fd) {
+  std::string test_lib(GetTestLibraryPath());
+  android::base::unique_fd fd(open(test_lib.c_str(), O_RDONLY | O_CLOEXEC));
+  ASSERT_NE(fd.get(), -1);
+  off_t file_size = lseek(fd, 0, SEEK_END);
+  ASSERT_EQ(lseek(fd, 0, SEEK_SET), 0);
+  std::vector<uint8_t> contents(file_size);
+  ASSERT_TRUE(android::base::ReadFully(fd, contents.data(), contents.size()));
+
+  // Put the shared library data at a pagesize() offset.
+  ASSERT_EQ(lseek(out_fd, 4 * getpagesize(), SEEK_CUR), 4 * getpagesize());
+  ASSERT_EQ(static_cast<size_t>(write(out_fd, contents.data(), contents.size())), contents.size());
+}
+
+TEST_F(CrasherTest, non_zero_offset_in_library) {
+  int intercept_result;
+  unique_fd output_fd;
+  TemporaryFile tf;
+  CreateEmbeddedLibrary(tf.fd);
+  StartProcess([&tf]() {
+    android_dlextinfo extinfo{};
+    extinfo.flags = ANDROID_DLEXT_USE_LIBRARY_FD | ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET;
+    extinfo.library_fd = tf.fd;
+    extinfo.library_fd_offset = 4 * getpagesize();
+    void* handle = android_dlopen_ext(tf.path, RTLD_NOW, &extinfo);
+    if (handle == nullptr) {
+      _exit(1);
+    }
+    void (*crash_func)() = reinterpret_cast<void (*)()>(dlsym(handle, "crash"));
+    if (crash_func == nullptr) {
+      _exit(1);
+    }
+    crash_func();
+  });
+
+  StartIntercept(&output_fd);
+  FinishCrasher();
+  AssertDeath(SIGSEGV);
+  FinishIntercept(&intercept_result);
+
+  ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
+
+  std::string result;
+  ConsumeFd(std::move(output_fd), &result);
+
+  // Verify the crash includes an offset value in the backtrace.
+  std::string match_str = android::base::StringPrintf("%s\\!libcrash_test.so \\(offset 0x%x\\)",
+                                                      tf.path, 4 * getpagesize());
+  ASSERT_MATCH(result, match_str);
+}
+
+static bool CopySharedLibrary(const char* tmp_dir, std::string* tmp_so_name) {
+  std::string test_lib(GetTestLibraryPath());
 
   *tmp_so_name = std::string(tmp_dir) + "/libcrash_test.so";
   std::string cp_cmd = android::base::StringPrintf("cp %s %s", test_lib.c_str(), tmp_dir);
diff --git a/debuggerd/handler/debuggerd_handler.cpp b/debuggerd/handler/debuggerd_handler.cpp
index 7120d73..baa5bfb 100644
--- a/debuggerd/handler/debuggerd_handler.cpp
+++ b/debuggerd/handler/debuggerd_handler.cpp
@@ -395,6 +395,7 @@
     ASSERT_SAME_OFFSET(scudo_region_info, scudo_region_info);
     ASSERT_SAME_OFFSET(scudo_ring_buffer, scudo_ring_buffer);
     ASSERT_SAME_OFFSET(scudo_ring_buffer_size, scudo_ring_buffer_size);
+    ASSERT_SAME_OFFSET(recoverable_gwp_asan_crash, recoverable_gwp_asan_crash);
 #undef ASSERT_SAME_OFFSET
 
     iovs[3] = {.iov_base = &thread_info->process_info,
@@ -565,17 +566,37 @@
     process_info = g_callbacks.get_process_info();
   }
 
+  // GWP-ASan catches use-after-free and heap-buffer-overflow by using PROT_NONE
+  // guard pages, which lead to SEGV. Normally, debuggerd prints a bug report
+  // and the process terminates, but in some cases, we actually want to print
+  // the bug report and let the signal handler return, and restart the process.
+  // In order to do that, we need to disable GWP-ASan's guard pages. The
+  // following callbacks handle this case.
+  gwp_asan_callbacks_t gwp_asan_callbacks = g_callbacks.get_gwp_asan_callbacks();
+  if (signal_number == SIGSEGV && signal_has_si_addr(info) &&
+      gwp_asan_callbacks.debuggerd_needs_gwp_asan_recovery &&
+      gwp_asan_callbacks.debuggerd_gwp_asan_pre_crash_report &&
+      gwp_asan_callbacks.debuggerd_gwp_asan_post_crash_report &&
+      gwp_asan_callbacks.debuggerd_needs_gwp_asan_recovery(info->si_addr)) {
+    gwp_asan_callbacks.debuggerd_gwp_asan_pre_crash_report(info->si_addr);
+    process_info.recoverable_gwp_asan_crash = true;
+  }
+
   // If sival_int is ~0, it means that the fallback handler has been called
   // once before and this function is being called again to dump the stack
   // of a specific thread. It is possible that the prctl call might return 1,
   // then return 0 in subsequent calls, so check the sival_int to determine if
   // the fallback handler should be called first.
-  if (si_val == kDebuggerdFallbackSivalUintptrRequestDump ||
-      prctl(PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0) == 1) {
+  bool no_new_privs = prctl(PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0) == 1;
+  if (si_val == kDebuggerdFallbackSivalUintptrRequestDump || no_new_privs) {
     // This check might be racy if another thread sets NO_NEW_PRIVS, but this should be unlikely,
     // you can only set NO_NEW_PRIVS to 1, and the effect should be at worst a single missing
     // ANR trace.
     debuggerd_fallback_handler(info, ucontext, process_info.abort_msg);
+    if (no_new_privs && process_info.recoverable_gwp_asan_crash) {
+      gwp_asan_callbacks.debuggerd_gwp_asan_post_crash_report(info->si_addr);
+      return;
+    }
     resend_signal(info);
     return;
   }
@@ -649,6 +670,9 @@
     // If the signal is fatal, don't unlock the mutex to prevent other crashing threads from
     // starting to dump right before our death.
     pthread_mutex_unlock(&crash_mutex);
+  } else if (process_info.recoverable_gwp_asan_crash) {
+    gwp_asan_callbacks.debuggerd_gwp_asan_post_crash_report(info->si_addr);
+    pthread_mutex_unlock(&crash_mutex);
   }
 #ifdef __aarch64__
   else if (info->si_signo == SIGSEGV &&
@@ -727,3 +751,52 @@
 
   debuggerd_register_handlers(&action);
 }
+
+// When debuggerd's signal handler is the first handler called, it's great at
+// handling the recoverable GWP-ASan mode. For apps, sigchain (from libart) is
+// always the first signal handler, and so the following function is what
+// sigchain must call before processing the signal. This allows for processing
+// of a potentially recoverable GWP-ASan crash. If the signal requires GWP-ASan
+// recovery, then dump a report (via the regular debuggerd hanndler), and patch
+// up the allocator, and allow the process to continue (indicated by returning
+// 'true'). If the crash has nothing to do with GWP-ASan, or recovery isn't
+// possible, return 'false'.
+bool debuggerd_handle_signal(int signal_number, siginfo_t* info, void* context) {
+  if (signal_number != SIGSEGV || !signal_has_si_addr(info)) return false;
+
+  gwp_asan_callbacks_t gwp_asan_callbacks = g_callbacks.get_gwp_asan_callbacks();
+  if (gwp_asan_callbacks.debuggerd_needs_gwp_asan_recovery == nullptr ||
+      gwp_asan_callbacks.debuggerd_gwp_asan_pre_crash_report == nullptr ||
+      gwp_asan_callbacks.debuggerd_gwp_asan_post_crash_report == nullptr ||
+      !gwp_asan_callbacks.debuggerd_needs_gwp_asan_recovery(info->si_addr)) {
+    return false;
+  }
+
+  // Only dump a crash report for the first GWP-ASan crash. ActivityManager
+  // doesn't like it when an app crashes multiple times, and is even more strict
+  // about an app crashing multiple times in a short time period. While the app
+  // won't crash fully when we do GWP-ASan recovery, ActivityManager still gets
+  // the information about the crash through the DropBoxManager service. If an
+  // app has multiple back-to-back GWP-ASan crashes, this would lead to the app
+  // being killed, which defeats the purpose of having the recoverable mode. To
+  // mitigate against this, only generate a debuggerd crash report for the first
+  // GWP-ASan crash encountered. We still need to do the patching up of the
+  // allocator though, so do that.
+  static pthread_mutex_t first_crash_mutex = PTHREAD_MUTEX_INITIALIZER;
+  pthread_mutex_lock(&first_crash_mutex);
+  static bool first_crash = true;
+
+  if (first_crash) {
+    // `debuggerd_signal_handler` will call
+    // `debuggerd_gwp_asan_(pre|post)_crash_report`, so no need to manually call
+    // them here.
+    debuggerd_signal_handler(signal_number, info, context);
+    first_crash = false;
+  } else {
+    gwp_asan_callbacks.debuggerd_gwp_asan_pre_crash_report(info->si_addr);
+    gwp_asan_callbacks.debuggerd_gwp_asan_post_crash_report(info->si_addr);
+  }
+
+  pthread_mutex_unlock(&first_crash_mutex);
+  return true;
+}
diff --git a/debuggerd/include/debuggerd/handler.h b/debuggerd/include/debuggerd/handler.h
index 1f9f4e2..ebb5372 100644
--- a/debuggerd/include/debuggerd/handler.h
+++ b/debuggerd/include/debuggerd/handler.h
@@ -35,7 +35,7 @@
 
 // When updating this data structure, CrashInfoDataDynamic and the code in
 // ReadCrashInfo() must also be updated.
-struct debugger_process_info {
+struct __attribute__((packed)) debugger_process_info {
   void* abort_msg;
   void* fdsan_table;
   const gwp_asan::AllocatorState* gwp_asan_state;
@@ -44,16 +44,28 @@
   const char* scudo_region_info;
   const char* scudo_ring_buffer;
   size_t scudo_ring_buffer_size;
+  bool recoverable_gwp_asan_crash;
 };
 
+// GWP-ASan calbacks to support the recoverable mode. Separate from the
+// debuggerd_callbacks_t because these values aren't available at debuggerd_init
+// time, and have to be synthesized on request.
+typedef struct {
+  bool (*debuggerd_needs_gwp_asan_recovery)(void* fault_addr);
+  void (*debuggerd_gwp_asan_pre_crash_report)(void* fault_addr);
+  void (*debuggerd_gwp_asan_post_crash_report)(void* fault_addr);
+} gwp_asan_callbacks_t;
+
 // These callbacks are called in a signal handler, and thus must be async signal safe.
 // If null, the callbacks will not be called.
 typedef struct {
   debugger_process_info (*get_process_info)();
+  gwp_asan_callbacks_t (*get_gwp_asan_callbacks)();
   void (*post_dump)();
 } debuggerd_callbacks_t;
 
 void debuggerd_init(debuggerd_callbacks_t* callbacks);
+bool debuggerd_handle_signal(int signal_number, siginfo_t* info, void* context);
 
 // DEBUGGER_ACTION_DUMP_TOMBSTONE and DEBUGGER_ACTION_DUMP_BACKTRACE are both
 // triggered via BIONIC_SIGNAL_DEBUGGER. The debugger_action_t is sent via si_value
diff --git a/debuggerd/libdebuggerd/tombstone_proto_to_text.cpp b/debuggerd/libdebuggerd/tombstone_proto_to_text.cpp
index a05bcec..e4d68f8 100644
--- a/debuggerd/libdebuggerd/tombstone_proto_to_text.cpp
+++ b/debuggerd/libdebuggerd/tombstone_proto_to_text.cpp
@@ -176,8 +176,14 @@
       build_id = StringPrintf(" (BuildId: %s)", frame.build_id().c_str());
     }
 
-    CB(should_log, "      #%02d pc %0*" PRIx64 "  %s%s%s", index++, pointer_width(tombstone) * 2,
-       frame.rel_pc(), frame.file_name().c_str(), function.c_str(), build_id.c_str());
+    std::string line =
+        StringPrintf("      #%02d pc %0*" PRIx64 "  %s", index++, pointer_width(tombstone) * 2,
+                     frame.rel_pc(), frame.file_name().c_str());
+    if (frame.file_map_offset() != 0) {
+      line += StringPrintf(" (offset 0x%" PRIx64 ")", frame.file_map_offset());
+    }
+    line += function + build_id;
+    CB(should_log, "%s", line.c_str());
   }
 }
 
diff --git a/debuggerd/protocol.h b/debuggerd/protocol.h
index e7cb218..b60cf5b 100644
--- a/debuggerd/protocol.h
+++ b/debuggerd/protocol.h
@@ -99,6 +99,7 @@
   uintptr_t scudo_region_info;
   uintptr_t scudo_ring_buffer;
   size_t scudo_ring_buffer_size;
+  bool recoverable_gwp_asan_crash;
 };
 
 struct __attribute__((__packed__)) CrashInfo {
diff --git a/fastboot/Android.bp b/fastboot/Android.bp
index 47830ef..f66b01d 100644
--- a/fastboot/Android.bp
+++ b/fastboot/Android.bp
@@ -286,6 +286,7 @@
         "fastboot.cpp",
         "fs.cpp",
         "socket.cpp",
+        "super_flash_helper.cpp",
         "tcp.cpp",
         "udp.cpp",
         "util.cpp",
diff --git a/fastboot/fastboot.cpp b/fastboot/fastboot.cpp
index 9676f87..e739404 100644
--- a/fastboot/fastboot.cpp
+++ b/fastboot/fastboot.cpp
@@ -53,6 +53,7 @@
 
 #include <android-base/endian.h>
 #include <android-base/file.h>
+#include <android-base/logging.h>
 #include <android-base/macros.h>
 #include <android-base/parseint.h>
 #include <android-base/parsenetaddress.h>
@@ -62,6 +63,7 @@
 #include <build/version.h>
 #include <libavb/libavb.h>
 #include <liblp/liblp.h>
+#include <liblp/super_layout_builder.h>
 #include <platform_tools_version.h>
 #include <sparse/sparse.h>
 #include <ziparchive/zip_archive.h>
@@ -71,6 +73,8 @@
 #include "diagnose_usb.h"
 #include "fastboot_driver.h"
 #include "fs.h"
+#include "super_flash_helper.h"
+#include "task.h"
 #include "tcp.h"
 #include "transport.h"
 #include "udp.h"
@@ -113,7 +117,7 @@
 
 struct fastboot_buffer {
     enum fb_buffer_type type;
-    void* data;
+    std::vector<SparsePtr> files;
     int64_t sz;
     unique_fd fd;
     int64_t image_size;
@@ -246,14 +250,6 @@
     fprintf(stderr, "(bootloader) %s\n", info.c_str());
 }
 
-static int64_t get_file_size(borrowed_fd fd) {
-    struct stat sb;
-    if (fstat(fd.get(), &sb) == -1) {
-        die("could not get file size");
-    }
-    return sb.st_size;
-}
-
 bool ReadFileToVector(const std::string& file, std::vector<char>* out) {
     out->clear();
 
@@ -824,27 +820,32 @@
     fprintf(stderr, "--------------------------------------------\n");
 }
 
-static struct sparse_file** load_sparse_files(int fd, int64_t max_size) {
-    struct sparse_file* s = sparse_file_import_auto(fd, false, true);
-    if (!s) die("cannot sparse read file");
-
+static std::vector<SparsePtr> resparse_file(sparse_file* s, int64_t max_size) {
     if (max_size <= 0 || max_size > std::numeric_limits<uint32_t>::max()) {
         die("invalid max size %" PRId64, max_size);
     }
 
-    int files = sparse_file_resparse(s, max_size, nullptr, 0);
+    const int files = sparse_file_resparse(s, max_size, nullptr, 0);
     if (files < 0) die("Failed to resparse");
 
-    sparse_file** out_s =
-            reinterpret_cast<sparse_file**>(calloc(sizeof(struct sparse_file*), files + 1));
-    if (!out_s) die("Failed to allocate sparse file array");
+    auto temp = std::make_unique<sparse_file*[]>(files);
+    const int rv = sparse_file_resparse(s, max_size, temp.get(), files);
+    if (rv < 0) die("Failed to resparse");
 
-    files = sparse_file_resparse(s, max_size, out_s, files);
-    if (files < 0) die("Failed to resparse");
-
+    std::vector<SparsePtr> out_s;
+    for (int i = 0; i < files; i++) {
+        out_s.emplace_back(temp[i], sparse_file_destroy);
+    }
     return out_s;
 }
 
+static std::vector<SparsePtr> load_sparse_files(int fd, int64_t max_size) {
+    SparsePtr s(sparse_file_import_auto(fd, false, true), sparse_file_destroy);
+    if (!s) die("cannot sparse read file");
+
+    return resparse_file(s.get(), max_size);
+}
+
 static uint64_t get_uint_var(const char* var_name) {
     std::string value_str;
     if (fb->GetVar(var_name, &value_str) != fastboot::SUCCESS || value_str.empty()) {
@@ -903,15 +904,13 @@
     int64_t limit = get_sparse_limit(sz);
     buf->fd = std::move(fd);
     if (limit) {
-        sparse_file** s = load_sparse_files(buf->fd.get(), limit);
-        if (s == nullptr) {
+        buf->files = load_sparse_files(buf->fd.get(), limit);
+        if (buf->files.empty()) {
             return false;
         }
         buf->type = FB_BUFFER_SPARSE;
-        buf->data = s;
     } else {
         buf->type = FB_BUFFER_FD;
-        buf->data = nullptr;
         buf->sz = sz;
     }
 
@@ -996,6 +995,8 @@
            fb->GetVar("partition-type:vbmeta_b", &partition_type) == fastboot::SUCCESS;
 }
 
+// Note: this only works in userspace fastboot. In the bootloader, use
+// should_flash_in_userspace().
 static bool is_logical(const std::string& partition) {
     std::string value;
     return fb->GetVar("is-logical:" + partition, &value) == fastboot::SUCCESS && value == "yes";
@@ -1078,9 +1079,16 @@
     lseek(buf->fd.get(), 0, SEEK_SET);
 }
 
-static void flash_buf(const std::string& partition, struct fastboot_buffer* buf) {
-    sparse_file** s;
+static void flash_partition_files(const std::string& partition,
+                                  const std::vector<SparsePtr>& files) {
+    for (size_t i = 0; i < files.size(); i++) {
+        sparse_file* s = files[i].get();
+        int64_t sz = sparse_file_len(s, true, false);
+        fb->FlashPartition(partition, s, sz, i + 1, files.size());
+    }
+}
 
+static void flash_buf(const std::string& partition, struct fastboot_buffer* buf) {
     if (partition == "boot" || partition == "boot_a" || partition == "boot_b" ||
         partition == "init_boot" || partition == "init_boot_a" || partition == "init_boot_b" ||
         partition == "recovery" || partition == "recovery_a" || partition == "recovery_b") {
@@ -1103,18 +1111,7 @@
 
     switch (buf->type) {
         case FB_BUFFER_SPARSE: {
-            std::vector<std::pair<sparse_file*, int64_t>> sparse_files;
-            s = reinterpret_cast<sparse_file**>(buf->data);
-            while (*s) {
-                int64_t sz = sparse_file_len(*s, true, false);
-                sparse_files.emplace_back(*s, sz);
-                ++s;
-            }
-
-            for (size_t i = 0; i < sparse_files.size(); ++i) {
-                const auto& pair = sparse_files[i];
-                fb->FlashPartition(partition, pair.first, pair.second, i + 1, sparse_files.size());
-            }
+            flash_partition_files(partition, buf->files);
             break;
         }
         case FB_BUFFER_FD:
@@ -1402,13 +1399,6 @@
     }
 }
 
-class ImageSource {
-  public:
-    virtual ~ImageSource(){};
-    virtual bool ReadFile(const std::string& name, std::vector<char>* out) const = 0;
-    virtual unique_fd OpenFile(const std::string& name) const = 0;
-};
-
 class FlashAllTool {
   public:
     FlashAllTool(const ImageSource& source, const std::string& slot_override, bool skip_secondary,
@@ -1418,20 +1408,30 @@
 
   private:
     void CheckRequirements();
-    void DetermineSecondarySlot();
+    void DetermineSlot();
     void CollectImages();
     void FlashImages(const std::vector<std::pair<const Image*, std::string>>& images);
     void FlashImage(const Image& image, const std::string& slot, fastboot_buffer* buf);
     void UpdateSuperPartition();
+    bool OptimizedFlashSuper();
+
+    // If the image uses the default slot, or the user specified "all", then
+    // the paired string will be empty. If the image requests a specific slot
+    // (for example, system_other) it is specified instead.
+    using ImageEntry = std::pair<const Image*, std::string>;
+
+    std::string GetPartitionName(const ImageEntry& entry);
 
     const ImageSource& source_;
     std::string slot_override_;
     bool skip_secondary_;
     bool wipe_;
     bool force_flash_;
+    std::string current_slot_;
     std::string secondary_slot_;
-    std::vector<std::pair<const Image*, std::string>> boot_images_;
-    std::vector<std::pair<const Image*, std::string>> os_images_;
+
+    std::vector<ImageEntry> boot_images_;
+    std::vector<ImageEntry> os_images_;
 };
 
 FlashAllTool::FlashAllTool(const ImageSource& source, const std::string& slot_override,
@@ -1454,7 +1454,7 @@
         set_active(slot_override_);
     }
 
-    DetermineSecondarySlot();
+    DetermineSlot();
     CollectImages();
 
     CancelSnapshotIfNeeded();
@@ -1463,24 +1463,92 @@
     // or in bootloader fastboot.
     FlashImages(boot_images_);
 
-    // Sync the super partition. This will reboot to userspace fastboot if needed.
-    UpdateSuperPartition();
+    if (!OptimizedFlashSuper()) {
+        // Sync the super partition. This will reboot to userspace fastboot if needed.
+        UpdateSuperPartition();
 
-    // Resize any logical partition to 0, so each partition is reset to 0
-    // extents, and will achieve more optimal allocation.
-    for (const auto& [image, slot] : os_images_) {
-        auto resize_partition = [](const std::string& partition) -> void {
-            if (is_logical(partition)) {
-                fb->ResizePartition(partition, "0");
-            }
-        };
-        do_for_partitions(image->part_name, slot, resize_partition, false);
+        // Resize any logical partition to 0, so each partition is reset to 0
+        // extents, and will achieve more optimal allocation.
+        for (const auto& [image, slot] : os_images_) {
+            auto resize_partition = [](const std::string& partition) -> void {
+                if (is_logical(partition)) {
+                    fb->ResizePartition(partition, "0");
+                }
+            };
+            do_for_partitions(image->part_name, slot, resize_partition, false);
+        }
     }
 
     // Flash OS images, resizing logical partitions as needed.
     FlashImages(os_images_);
 }
 
+bool FlashAllTool::OptimizedFlashSuper() {
+    if (!supports_AB()) {
+        LOG(VERBOSE) << "Cannot optimize flashing super on non-AB device";
+        return false;
+    }
+    if (slot_override_ == "all") {
+        LOG(VERBOSE) << "Cannot optimize flashing super for all slots";
+        return false;
+    }
+
+    // Does this device use dynamic partitions at all?
+    unique_fd fd = source_.OpenFile("super_empty.img");
+    if (fd < 0) {
+        LOG(VERBOSE) << "could not open super_empty.img";
+        return false;
+    }
+
+    // Try to find whether there is a super partition.
+    std::string super_name;
+    if (fb->GetVar("super-partition-name", &super_name) != fastboot::SUCCESS) {
+        super_name = "super";
+    }
+    std::string partition_size_str;
+    if (fb->GetVar("partition-size:" + super_name, &partition_size_str) != fastboot::SUCCESS) {
+        LOG(VERBOSE) << "Cannot optimize super flashing: could not determine super partition";
+        return false;
+    }
+
+    SuperFlashHelper helper(source_);
+    if (!helper.Open(fd)) {
+        return false;
+    }
+
+    for (const auto& entry : os_images_) {
+        auto partition = GetPartitionName(entry);
+        auto image = entry.first;
+
+        if (!helper.AddPartition(partition, image->img_name, image->optional_if_no_image)) {
+            return false;
+        }
+    }
+
+    auto s = helper.GetSparseLayout();
+    if (!s) {
+        return false;
+    }
+
+    std::vector<SparsePtr> files;
+    if (int limit = get_sparse_limit(sparse_file_len(s.get(), false, false))) {
+        files = resparse_file(s.get(), limit);
+    } else {
+        files.emplace_back(std::move(s));
+    }
+
+    // Send the data to the device.
+    flash_partition_files(super_name, files);
+
+    // Remove images that we already flashed, just in case we have non-dynamic OS images.
+    auto remove_if_callback = [&, this](const ImageEntry& entry) -> bool {
+        return helper.WillFlash(GetPartitionName(entry));
+    };
+    os_images_.erase(std::remove_if(os_images_.begin(), os_images_.end(), remove_if_callback),
+                     os_images_.end());
+    return true;
+}
+
 void FlashAllTool::CheckRequirements() {
     std::vector<char> contents;
     if (!source_.ReadFile("android-info.txt", &contents)) {
@@ -1489,7 +1557,13 @@
     ::CheckRequirements({contents.data(), contents.size()}, force_flash_);
 }
 
-void FlashAllTool::DetermineSecondarySlot() {
+void FlashAllTool::DetermineSlot() {
+    if (slot_override_.empty()) {
+        current_slot_ = get_current_slot();
+    } else {
+        current_slot_ = slot_override_;
+    }
+
     if (skip_secondary_) {
         return;
     }
@@ -1588,6 +1662,20 @@
     }
 }
 
+std::string FlashAllTool::GetPartitionName(const ImageEntry& entry) {
+    auto slot = entry.second;
+    if (slot.empty()) {
+        slot = current_slot_;
+    }
+    if (slot.empty()) {
+        return entry.first->part_name;
+    }
+    if (slot == "all") {
+        LOG(FATAL) << "Cannot retrieve a singular name when using all slots";
+    }
+    return entry.first->part_name + "_" + slot;
+}
+
 class ZipImageSource final : public ImageSource {
   public:
     explicit ZipImageSource(ZipArchiveHandle zip) : zip_(zip) {}
@@ -1782,20 +1870,7 @@
     if (!metadata) {
         return false;
     }
-    for (const auto& partition : metadata->partitions) {
-        auto candidate = android::fs_mgr::GetPartitionName(partition);
-        if (partition.attributes & LP_PARTITION_ATTR_SLOT_SUFFIXED) {
-            // On retrofit devices, we don't know if, or whether, the A or B
-            // slot has been flashed for dynamic partitions. Instead we add
-            // both names to the list as a conservative guess.
-            if (candidate + "_a" == partition_name || candidate + "_b" == partition_name) {
-                return true;
-            }
-        } else if (candidate == partition_name) {
-            return true;
-        }
-    }
-    return false;
+    return should_flash_in_userspace(*metadata.get(), partition_name);
 }
 
 static bool wipe_super(const android::fs_mgr::LpMetadata& metadata, const std::string& slot,
@@ -1868,7 +1943,19 @@
     }
 }
 
+static void FastbootLogger(android::base::LogId /* id */, android::base::LogSeverity /* severity */,
+                           const char* /* tag */, const char* /* file */, unsigned int /* line */,
+                           const char* message) {
+    verbose("%s", message);
+}
+
+static void FastbootAborter(const char* message) {
+    die("%s", message);
+}
+
 int FastBootTool::Main(int argc, char* argv[]) {
+    android::base::InitLogging(argv, FastbootLogger, FastbootAborter);
+
     bool wants_wipe = false;
     bool wants_reboot = false;
     bool wants_reboot_bootloader = false;
diff --git a/fastboot/fastboot.h b/fastboot/fastboot.h
index c23793a..d7ad5df 100644
--- a/fastboot/fastboot.h
+++ b/fastboot/fastboot.h
@@ -25,6 +25,7 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+#pragma once
 
 #include <bootimg.h>
 
diff --git a/fastboot/fastboot_driver.h b/fastboot/fastboot_driver.h
index bccd668..b422c91 100644
--- a/fastboot/fastboot_driver.h
+++ b/fastboot/fastboot_driver.h
@@ -32,6 +32,7 @@
 #include <string>
 #include <vector>
 
+#include <android-base/endian.h>
 #include <android-base/logging.h>
 #include <android-base/stringprintf.h>
 #include <android-base/unique_fd.h>
diff --git a/fastboot/super_flash_helper.cpp b/fastboot/super_flash_helper.cpp
new file mode 100644
index 0000000..b617ce8
--- /dev/null
+++ b/fastboot/super_flash_helper.cpp
@@ -0,0 +1,125 @@
+//
+// Copyright (C) 2023 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "super_flash_helper.h"
+
+#include <android-base/logging.h>
+
+#include "util.h"
+
+using android::base::borrowed_fd;
+using android::base::unique_fd;
+using android::fs_mgr::SuperImageExtent;
+
+SuperFlashHelper::SuperFlashHelper(const ImageSource& source) : source_(source) {}
+
+bool SuperFlashHelper::Open(borrowed_fd fd) {
+    if (!builder_.Open(fd)) {
+        LOG(VERBOSE) << "device does not support optimized super flashing";
+        return false;
+    }
+
+    base_metadata_ = builder_.Export();
+    return !!base_metadata_;
+}
+
+bool SuperFlashHelper::IncludeInSuper(const std::string& partition) {
+    return should_flash_in_userspace(*base_metadata_.get(), partition);
+}
+
+bool SuperFlashHelper::AddPartition(const std::string& partition, const std::string& image_name,
+                                    bool optional) {
+    if (!IncludeInSuper(partition)) {
+        return true;
+    }
+    auto iter = image_fds_.find(image_name);
+    if (iter == image_fds_.end()) {
+        unique_fd fd = source_.OpenFile(image_name);
+        if (fd < 0) {
+            if (!optional) {
+                LOG(VERBOSE) << "could not find partition image: " << image_name;
+                return false;
+            }
+            return true;
+        }
+        if (is_sparse_file(fd)) {
+            LOG(VERBOSE) << "cannot optimize dynamic partitions with sparse images";
+            return false;
+        }
+        iter = image_fds_.emplace(image_name, std::move(fd)).first;
+    }
+
+    if (!builder_.AddPartition(partition, image_name, get_file_size(iter->second))) {
+        return false;
+    }
+
+    will_flash_.emplace(partition);
+    return true;
+}
+
+SparsePtr SuperFlashHelper::GetSparseLayout() {
+    // Cache extents since the sparse ptr depends on data pointers.
+    if (extents_.empty()) {
+        extents_ = builder_.GetImageLayout();
+        if (extents_.empty()) {
+            LOG(VERBOSE) << "device does not support optimized super flashing";
+            return {nullptr, nullptr};
+        }
+    }
+
+    unsigned int block_size = base_metadata_->geometry.logical_block_size;
+    int64_t flashed_size = extents_.back().offset + extents_.back().size;
+    SparsePtr s(sparse_file_new(block_size, flashed_size), sparse_file_destroy);
+
+    for (const auto& extent : extents_) {
+        if (extent.offset / block_size > UINT_MAX) {
+            // Super image is too big to send via sparse files (>8TB).
+            LOG(VERBOSE) << "super image is too big to flash";
+            return {nullptr, nullptr};
+        }
+        unsigned int block = extent.offset / block_size;
+
+        int rv = 0;
+        switch (extent.type) {
+            case SuperImageExtent::Type::DONTCARE:
+                break;
+            case SuperImageExtent::Type::ZERO:
+                rv = sparse_file_add_fill(s.get(), 0, extent.size, block);
+                break;
+            case SuperImageExtent::Type::DATA:
+                rv = sparse_file_add_data(s.get(), extent.blob->data(), extent.size, block);
+                break;
+            case SuperImageExtent::Type::PARTITION: {
+                auto iter = image_fds_.find(extent.image_name);
+                if (iter == image_fds_.end()) {
+                    LOG(FATAL) << "image added but not found: " << extent.image_name;
+                    return {nullptr, nullptr};
+                }
+                rv = sparse_file_add_fd(s.get(), iter->second.get(), extent.image_offset,
+                                        extent.size, block);
+                break;
+            }
+            default:
+                LOG(VERBOSE) << "unrecognized extent type in super image layout";
+                return {nullptr, nullptr};
+        }
+        if (rv) {
+            LOG(VERBOSE) << "sparse failure building super image layout";
+            return {nullptr, nullptr};
+        }
+    }
+    return s;
+}
diff --git a/fastboot/super_flash_helper.h b/fastboot/super_flash_helper.h
new file mode 100644
index 0000000..29c15d0
--- /dev/null
+++ b/fastboot/super_flash_helper.h
@@ -0,0 +1,56 @@
+//
+// Copyright (C) 2023 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#pragma once
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+
+#include <android-base/unique_fd.h>
+#include <liblp/liblp.h>
+#include <liblp/super_layout_builder.h>
+
+#include "util.h"
+
+class SuperFlashHelper final {
+  public:
+    explicit SuperFlashHelper(const ImageSource& source);
+
+    bool Open(android::base::borrowed_fd fd);
+    bool IncludeInSuper(const std::string& partition);
+    bool AddPartition(const std::string& partition, const std::string& image_name, bool optional);
+
+    // Note: the SparsePtr if non-null should not outlive SuperFlashHelper, since
+    // it depends on open fds and data pointers.
+    SparsePtr GetSparseLayout();
+
+    bool WillFlash(const std::string& partition) const {
+        return will_flash_.find(partition) != will_flash_.end();
+    }
+
+  private:
+    const ImageSource& source_;
+    android::fs_mgr::SuperLayoutBuilder builder_;
+    std::unique_ptr<android::fs_mgr::LpMetadata> base_metadata_;
+    std::vector<android::fs_mgr::SuperImageExtent> extents_;
+
+    // Cache open image fds. This keeps them alive while we flash the sparse
+    // file.
+    std::unordered_map<std::string, android::base::unique_fd> image_fds_;
+    std::unordered_set<std::string> will_flash_;
+};
diff --git a/fastboot/task.h b/fastboot/task.h
new file mode 100644
index 0000000..8b3fce9
--- /dev/null
+++ b/fastboot/task.h
@@ -0,0 +1,31 @@
+//
+// Copyright (C) 2020 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+#pragma once
+
+#include <sstream>
+#include <string>
+
+#include "fastboot.h"
+#include "fastboot_driver.h"
+#include "util.h"
+
+class Task {
+  public:
+    Task() = default;
+    virtual void Run() = 0;
+    virtual bool Parse(const std::string& text) = 0;
+    virtual ~Task() = default;
+};
diff --git a/fastboot/util.cpp b/fastboot/util.cpp
index 900d6ea..ded54a5 100644
--- a/fastboot/util.cpp
+++ b/fastboot/util.cpp
@@ -30,11 +30,13 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-
+#include <sys/stat.h>
 #include <sys/time.h>
 
 #include "util.h"
 
+using android::base::borrowed_fd;
+
 static bool g_verbose = false;
 
 double now() {
@@ -73,3 +75,34 @@
     }
     fprintf(stderr, "\n");
 }
+
+bool should_flash_in_userspace(const android::fs_mgr::LpMetadata& metadata,
+                               const std::string& partition_name) {
+    for (const auto& partition : metadata.partitions) {
+        auto candidate = android::fs_mgr::GetPartitionName(partition);
+        if (partition.attributes & LP_PARTITION_ATTR_SLOT_SUFFIXED) {
+            // On retrofit devices, we don't know if, or whether, the A or B
+            // slot has been flashed for dynamic partitions. Instead we add
+            // both names to the list as a conservative guess.
+            if (candidate + "_a" == partition_name || candidate + "_b" == partition_name) {
+                return true;
+            }
+        } else if (candidate == partition_name) {
+            return true;
+        }
+    }
+    return false;
+}
+
+bool is_sparse_file(borrowed_fd fd) {
+    SparsePtr s(sparse_file_import(fd.get(), false, false), sparse_file_destroy);
+    return !!s;
+}
+
+int64_t get_file_size(borrowed_fd fd) {
+    struct stat sb;
+    if (fstat(fd.get(), &sb) == -1) {
+        die("could not get file size");
+    }
+    return sb.st_size;
+}
diff --git a/fastboot/util.h b/fastboot/util.h
index c719df2..290d0d5 100644
--- a/fastboot/util.h
+++ b/fastboot/util.h
@@ -4,8 +4,14 @@
 #include <stdlib.h>
 
 #include <string>
+#include <vector>
 
+#include <android-base/unique_fd.h>
 #include <bootimg.h>
+#include <liblp/liblp.h>
+#include <sparse/sparse.h>
+
+using SparsePtr = std::unique_ptr<sparse_file, decltype(&sparse_file_destroy)>;
 
 /* util stuff */
 double now();
@@ -19,3 +25,15 @@
 void verbose(const char* fmt, ...) __attribute__((__format__(__printf__, 1, 2)));
 
 void die(const std::string& str) __attribute__((__noreturn__));
+
+bool should_flash_in_userspace(const android::fs_mgr::LpMetadata& metadata,
+                               const std::string& partition_name);
+bool is_sparse_file(android::base::borrowed_fd fd);
+int64_t get_file_size(android::base::borrowed_fd fd);
+
+class ImageSource {
+  public:
+    virtual ~ImageSource(){};
+    virtual bool ReadFile(const std::string& name, std::vector<char>* out) const = 0;
+    virtual android::base::unique_fd OpenFile(const std::string& name) const = 0;
+};
diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp
index 1c1ab48..742cdfa 100644
--- a/fs_mgr/fs_mgr.cpp
+++ b/fs_mgr/fs_mgr.cpp
@@ -1176,6 +1176,10 @@
                     return false;
                 }
 
+                // dm-bow will not load if size is not a multiple of 4096
+                // rounding down does not hurt, since ext4 will only use full blocks
+                size &= ~7;
+
                 android::dm::DmTable table;
                 auto bowTarget =
                         std::make_unique<android::dm::DmTargetBow>(0, size, entry->blk_device);
diff --git a/fs_mgr/fs_mgr_priv.h b/fs_mgr/fs_mgr_priv.h
index 46f54cc..46cdb62 100644
--- a/fs_mgr/fs_mgr_priv.h
+++ b/fs_mgr/fs_mgr_priv.h
@@ -33,7 +33,7 @@
  */
 #define FS_MGR_CHECK(x) CHECK(x) << "in libfs_mgr "
 
-#define FS_MGR_TAG "[libfs_mgr]"
+#define FS_MGR_TAG "[libfs_mgr] "
 
 // Logs a message to kernel
 #define LINFO    LOG(INFO) << FS_MGR_TAG
diff --git a/fs_mgr/libfiemap/metadata.cpp b/fs_mgr/libfiemap/metadata.cpp
index b0dfb5c..22b8afb 100644
--- a/fs_mgr/libfiemap/metadata.cpp
+++ b/fs_mgr/libfiemap/metadata.cpp
@@ -30,6 +30,7 @@
 namespace fiemap {
 
 using namespace android::fs_mgr;
+using android::base::unique_fd;
 
 static constexpr uint32_t kMaxMetadataSize = 256 * 1024;
 
@@ -109,10 +110,18 @@
     if (exported->partitions.empty() && android::base::RemoveFileIfExists(metadata_file)) {
         return true;
     }
-    if (!WriteToImageFile(metadata_file, *exported.get())) {
+
+    unique_fd fd(open(metadata_file.c_str(), O_CREAT | O_RDWR | O_TRUNC | O_CLOEXEC | O_BINARY | O_SYNC, 0644));
+    if (fd < 0) {
+        LOG(ERROR) << "open failed: " << metadata_file;
+        return false;
+    }
+
+    if (!WriteToImageFile(fd, *exported.get())) {
         LOG(ERROR) << "Unable to save new metadata";
         return false;
     }
+
     return true;
 }
 
diff --git a/fs_mgr/libfs_avb/avb_ops.cpp b/fs_mgr/libfs_avb/avb_ops.cpp
index 46072bb..a119bfc 100644
--- a/fs_mgr/libfs_avb/avb_ops.cpp
+++ b/fs_mgr/libfs_avb/avb_ops.cpp
@@ -26,8 +26,10 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <linux/fs.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/ioctl.h>
 #include <sys/stat.h>
 
 #include <string>
@@ -96,13 +98,11 @@
     return AVB_IO_RESULT_OK;
 }
 
-static AvbIOResult no_op_get_size_of_partition(AvbOps* ops ATTRIBUTE_UNUSED,
-                                              const char* partition ATTRIBUTE_UNUSED,
-                                              uint64_t* out_size_num_byte) {
-    // The function is for bootloader to load entire content of AVB HASH partitions.
-    // In user-space, returns 0 as we only need to set up AVB HASHTHREE partitions.
-    *out_size_num_byte = 0;
-    return AVB_IO_RESULT_OK;
+static AvbIOResult get_size_of_partition(AvbOps* ops ATTRIBUTE_UNUSED,
+                                         const char* partition ATTRIBUTE_UNUSED,
+                                         uint64_t* out_size_num_byte) {
+    return FsManagerAvbOps::GetInstanceFromAvbOps(ops)->GetSizeOfPartition(partition,
+                                                                           out_size_num_byte);
 }
 
 // Converts a partition name (with ab_suffix) to the corresponding mount point.
@@ -131,7 +131,7 @@
     avb_ops_.validate_vbmeta_public_key = no_op_validate_vbmeta_public_key;
     avb_ops_.read_is_device_unlocked = no_op_read_is_device_unlocked;
     avb_ops_.get_unique_guid_for_partition = no_op_get_unique_guid_for_partition;
-    avb_ops_.get_size_of_partition = no_op_get_size_of_partition;
+    avb_ops_.get_size_of_partition = get_size_of_partition;
 
     // Sets user_data for GetInstanceFromAvbOps() to convert it back to FsManagerAvbOps.
     avb_ops_.user_data = this;
@@ -167,13 +167,8 @@
 
     return "";
 }
-
-AvbIOResult FsManagerAvbOps::ReadFromPartition(const char* partition, int64_t offset,
-                                               size_t num_bytes, void* buffer,
-                                               size_t* out_num_read) {
+std::string FsManagerAvbOps::GetPartitionPath(const char* partition) {
     std::string path = "/dev/block/by-name/"s + partition;
-
-    // Ensures the device path (a symlink created by init) is ready to access.
     if (!WaitForFile(path, 1s)) {
         LERROR << "Device path not found: " << path;
         // Falls back to logical path if the physical path is not found.
@@ -182,8 +177,36 @@
         // the bootloader failed to read a physical partition, it will failed to boot
         // the HLOS and we won't reach the code here.
         path = GetLogicalPath(partition);
-        if (path.empty() || !WaitForFile(path, 1s)) return AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION;
-        LINFO << "Fallback to use logical device path: " << path;
+        if (path.empty() || !WaitForFile(path, 1s)) return "";
+    }
+    return path;
+}
+
+AvbIOResult FsManagerAvbOps::GetSizeOfPartition(const char* partition,
+                                                uint64_t* out_size_num_byte) {
+    const auto path = GetPartitionPath(partition);
+    if (path.empty()) {
+        return AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION;
+    }
+    android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_CLOEXEC)));
+    if (fd < 0) {
+        PERROR << "Failed to open " << path;
+        return AVB_IO_RESULT_ERROR_IO;
+    }
+    int err = ioctl(fd, BLKGETSIZE64, out_size_num_byte);
+    if (err) {
+        *out_size_num_byte = 0;
+        return AVB_IO_RESULT_ERROR_IO;
+    }
+    return AVB_IO_RESULT_OK;
+}
+
+AvbIOResult FsManagerAvbOps::ReadFromPartition(const char* partition, int64_t offset,
+                                               size_t num_bytes, void* buffer,
+                                               size_t* out_num_read) {
+    std::string path = GetPartitionPath(partition);
+    if (path.empty()) {
+        return AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION;
     }
 
     android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_CLOEXEC)));
diff --git a/fs_mgr/libfs_avb/avb_ops.h b/fs_mgr/libfs_avb/avb_ops.h
index b39812d..12686a6 100644
--- a/fs_mgr/libfs_avb/avb_ops.h
+++ b/fs_mgr/libfs_avb/avb_ops.h
@@ -56,12 +56,14 @@
 
     AvbIOResult ReadFromPartition(const char* partition, int64_t offset, size_t num_bytes,
                                   void* buffer, size_t* out_num_read);
+    AvbIOResult GetSizeOfPartition(const char* partition, uint64_t* out_size_num_byte);
 
     AvbSlotVerifyResult AvbSlotVerify(const std::string& ab_suffix, AvbSlotVerifyFlags flags,
                                       std::vector<VBMetaData>* out_vbmeta_images);
 
   private:
     std::string GetLogicalPath(const std::string& partition_name);
+    std::string GetPartitionPath(const char* partition_name);
     AvbOps avb_ops_;
     Fstab fstab_;
 };
diff --git a/fs_mgr/libfs_avb/util.h b/fs_mgr/libfs_avb/util.h
index 427ab7c..29d1e9c 100644
--- a/fs_mgr/libfs_avb/util.h
+++ b/fs_mgr/libfs_avb/util.h
@@ -31,7 +31,7 @@
 using android::base::ErrnoError;
 using android::base::Result;
 
-#define FS_AVB_TAG "[libfs_avb]"
+#define FS_AVB_TAG "[libfs_avb] "
 
 // Logs a message to kernel
 #define LINFO LOG(INFO) << FS_AVB_TAG
diff --git a/fs_mgr/liblp/Android.bp b/fs_mgr/liblp/Android.bp
index 4b81c2c..996ffd7 100644
--- a/fs_mgr/liblp/Android.bp
+++ b/fs_mgr/liblp/Android.bp
@@ -39,6 +39,7 @@
     ],
     srcs: [
         "builder.cpp",
+        "super_layout_builder.cpp",
         "images.cpp",
         "partition_opener.cpp",
         "property_fetcher.cpp",
@@ -62,17 +63,6 @@
     export_include_dirs: ["include"],
 }
 
-filegroup {
-    name: "liblp_test_srcs",
-    srcs: [
-        "builder_test.cpp",
-        "device_test.cpp",
-        "io_test.cpp",
-        "test_partition_opener.cpp",
-        "utility_test.cpp",
-    ],
-}
-
 cc_defaults {
     name: "liblp_test_defaults",
     defaults: ["fs_mgr_defaults"],
@@ -82,22 +72,39 @@
     static_libs: [
         "libcutils",
         "libgmock",
-        "libfs_mgr",
         "liblp",
         "libcrypto_static",
     ] + liblp_lib_deps,
     header_libs: [
         "libstorage_literals_headers",
     ],
+    target: {
+        android: {
+            srcs: [
+                "device_test.cpp",
+                "io_test.cpp",
+            ],
+            static_libs: [
+                "libfs_mgr",
+            ],
+        }
+    },
     stl: "libc++_static",
-    srcs: [":liblp_test_srcs"],
+    srcs: [
+        "builder_test.cpp",
+        "super_layout_builder_test.cpp",
+        "test_partition_opener.cpp",
+        "utility_test.cpp",
+    ],
 }
 
 cc_test {
     name: "liblp_test",
     defaults: ["liblp_test_defaults"],
-    test_config: "liblp_test.xml",
     test_suites: ["device-tests"],
+    auto_gen_config: true,
+    require_root: true,
+    host_supported: true
 }
 
 cc_test {
diff --git a/fs_mgr/liblp/include/liblp/super_layout_builder.h b/fs_mgr/liblp/include/liblp/super_layout_builder.h
new file mode 100644
index 0000000..d920855
--- /dev/null
+++ b/fs_mgr/liblp/include/liblp/super_layout_builder.h
@@ -0,0 +1,104 @@
+//
+// Copyright (C) 2023 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+#pragma once
+
+#include <stdint.h>
+
+#include <memory>
+#include <ostream>
+#include <string>
+#include <unordered_map>
+#include <utility>
+
+#include <android-base/unique_fd.h>
+#include <liblp/builder.h>
+
+namespace android {
+namespace fs_mgr {
+
+struct SuperImageExtent {
+    enum class Type { INVALID, DATA, PARTITION, ZERO, DONTCARE };
+
+    SuperImageExtent(const SuperImageExtent& other) = default;
+    SuperImageExtent(SuperImageExtent&& other) = default;
+    SuperImageExtent(uint64_t offset, uint64_t size, Type type)
+        : offset(offset), size(size), type(type) {}
+
+    SuperImageExtent(uint64_t offset, std::shared_ptr<std::string> blob)
+        : SuperImageExtent(offset, blob->size(), Type::DATA) {
+        this->blob = blob;
+    }
+
+    SuperImageExtent(uint64_t offset, uint64_t size, const std::string& image_name,
+                     uint64_t image_offset)
+        : SuperImageExtent(offset, size, Type::PARTITION) {
+        this->image_name = image_name;
+        this->image_offset = image_offset;
+    }
+
+    SuperImageExtent& operator=(const SuperImageExtent& other) = default;
+    SuperImageExtent& operator=(SuperImageExtent&& other) = default;
+
+    bool operator<(const SuperImageExtent& other) const { return offset < other.offset; }
+    bool operator==(const SuperImageExtent& other) const;
+
+    // Location, size, and type of the extent.
+    uint64_t offset = 0;
+    uint64_t size = 0;
+    Type type = Type::INVALID;
+
+    // If type == DATA, this contains the bytes to write.
+    std::shared_ptr<std::string> blob;
+    // If type == PARTITION, this contains the partition image name and
+    // offset within that file.
+    std::string image_name;
+    uint64_t image_offset = 0;
+};
+
+// The SuperLayoutBuilder allows building a sparse view of a super image. This
+// is useful for efficient flashing, eg to bypass fastbootd and directly flash
+// super without physically building and storing the image.
+class SuperLayoutBuilder final {
+  public:
+    // Open a super_empty.img, return false on failure. This must be called to
+    // initialize the tool. If it returns false, either the image failed to
+    // parse, or the tool is not compatible with how the device is configured
+    // (in which case fastbootd should be preferred).
+    [[nodiscard]] bool Open(android::base::borrowed_fd fd);
+    [[nodiscard]] bool Open(const void* data, size_t bytes);
+    [[nodiscard]] bool Open(const LpMetadata& metadata);
+
+    // Add a partition's image and size to the work list. If false is returned,
+    // there was either a duplicate partition or not enough space in super.
+    bool AddPartition(const std::string& partition_name, const std::string& image_name,
+                      uint64_t partition_size);
+
+    // Return the list of extents describing the super image. If this list is
+    // empty, then there was an unrecoverable error in building the list.
+    std::vector<SuperImageExtent> GetImageLayout();
+
+    // Return the current metadata.
+    std::unique_ptr<LpMetadata> Export() const { return builder_->Export(); }
+
+  private:
+    std::unique_ptr<MetadataBuilder> builder_;
+    std::unordered_map<std::string, std::string> image_map_;
+};
+
+std::ostream& operator<<(std::ostream& stream, const SuperImageExtent& extent);
+
+}  // namespace fs_mgr
+}  // namespace android
diff --git a/fs_mgr/liblp/liblp_test.xml b/fs_mgr/liblp/liblp_test.xml
deleted file mode 100644
index 98414b1..0000000
--- a/fs_mgr/liblp/liblp_test.xml
+++ /dev/null
@@ -1,26 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!-- Copyright (C) 2019 The Android Open Source Project
-
-     Licensed under the Apache License, Version 2.0 (the "License");
-     you may not use this file except in compliance with the License.
-     You may obtain a copy of the License at
-
-          http://www.apache.org/licenses/LICENSE-2.0
-
-     Unless required by applicable law or agreed to in writing, software
-     distributed under the License is distributed on an "AS IS" BASIS,
-     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-     See the License for the specific language governing permissions and
-     limitations under the License.
--->
-<configuration description="Config for liblp_test">
-    <target_preparer class="com.android.tradefed.targetprep.RootTargetPreparer"/>
-    <target_preparer class="com.android.tradefed.targetprep.PushFilePreparer">
-        <option name="cleanup" value="true" />
-        <option name="push" value="liblp_test->/data/local/tmp/liblp_test" />
-    </target_preparer>
-    <test class="com.android.tradefed.testtype.GTest" >
-        <option name="native-test-device-path" value="/data/local/tmp" />
-        <option name="module-name" value="liblp_test" />
-    </test>
-</configuration>
diff --git a/fs_mgr/liblp/super_layout_builder.cpp b/fs_mgr/liblp/super_layout_builder.cpp
new file mode 100644
index 0000000..37f28e1
--- /dev/null
+++ b/fs_mgr/liblp/super_layout_builder.cpp
@@ -0,0 +1,241 @@
+//
+// Copyright (C) 2023 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+#include <liblp/super_layout_builder.h>
+
+#include <liblp/liblp.h>
+
+#include "images.h"
+#include "utility.h"
+#include "writer.h"
+
+using android::base::borrowed_fd;
+using android::base::unique_fd;
+
+namespace android {
+namespace fs_mgr {
+
+bool SuperLayoutBuilder::Open(borrowed_fd fd) {
+    auto metadata = ReadFromImageFile(fd.get());
+    if (!metadata) {
+        return false;
+    }
+    return Open(*metadata.get());
+}
+
+bool SuperLayoutBuilder::Open(const void* data, size_t size) {
+    auto metadata = ReadFromImageBlob(data, size);
+    if (!metadata) {
+        return false;
+    }
+    return Open(*metadata.get());
+}
+
+bool SuperLayoutBuilder::Open(const LpMetadata& metadata) {
+    for (const auto& partition : metadata.partitions) {
+        if (partition.attributes & LP_PARTITION_ATTR_SLOT_SUFFIXED) {
+            // Retrofit devices are not supported.
+            return false;
+        }
+        if (!(partition.attributes & LP_PARTITION_ATTR_READONLY)) {
+            // Writable partitions are not supported.
+            return false;
+        }
+    }
+    if (!metadata.extents.empty()) {
+        // Partitions that already have extents are not supported (should
+        // never be true of super_empty.img).
+        return false;
+    }
+    if (metadata.block_devices.size() != 1) {
+        // Only one "super" is supported.
+        return false;
+    }
+
+    builder_ = MetadataBuilder::New(metadata);
+    return !!builder_;
+}
+
+bool SuperLayoutBuilder::AddPartition(const std::string& partition_name,
+                                      const std::string& image_name, uint64_t partition_size) {
+    auto p = builder_->FindPartition(partition_name);
+    if (!p) {
+        return false;
+    }
+    if (!builder_->ResizePartition(p, partition_size)) {
+        return false;
+    }
+    image_map_.emplace(partition_name, image_name);
+    return true;
+}
+
+// Fill the space between each extent, if any, with either a fill or dontcare
+// extent. The caller constructs a sample extent to re-use.
+static bool AddGapExtents(std::vector<SuperImageExtent>* extents, SuperImageExtent::Type gap_type) {
+    std::vector<SuperImageExtent> old = std::move(*extents);
+    std::sort(old.begin(), old.end());
+
+    *extents = {};
+
+    uint64_t current_offset = 0;
+    for (const auto& extent : old) {
+        // Check for overlapping extents - this would be a serious error.
+        if (current_offset > extent.offset) {
+            LOG(INFO) << "Overlapping extents detected; cannot layout temporary super image";
+            return false;
+        }
+
+        if (extent.offset != current_offset) {
+            uint64_t gap_size = extent.offset - current_offset;
+            extents->emplace_back(current_offset, gap_size, gap_type);
+            current_offset = extent.offset;
+        }
+
+        extents->emplace_back(extent);
+        current_offset += extent.size;
+    }
+    return true;
+}
+
+std::vector<SuperImageExtent> SuperLayoutBuilder::GetImageLayout() {
+    auto metadata = builder_->Export();
+    if (!metadata) {
+        return {};
+    }
+
+    std::vector<SuperImageExtent> extents;
+
+    // Write the primary and backup copies of geometry.
+    std::string geometry_bytes = SerializeGeometry(metadata->geometry);
+    auto blob = std::make_shared<std::string>(std::move(geometry_bytes));
+
+    extents.emplace_back(0, GetPrimaryGeometryOffset(), SuperImageExtent::Type::ZERO);
+    extents.emplace_back(GetPrimaryGeometryOffset(), blob);
+    extents.emplace_back(GetBackupGeometryOffset(), blob);
+
+    // Write the primary and backup copies of each metadata slot. When flashing,
+    // all metadata copies are the same, even for different slots.
+    std::string metadata_bytes = SerializeMetadata(*metadata.get());
+
+    // Align metadata size to 4KB. This makes the layout easily compatible with
+    // libsparse.
+    static constexpr size_t kSparseAlignment = 4096;
+    size_t metadata_aligned_bytes;
+    if (!AlignTo(metadata_bytes.size(), kSparseAlignment, &metadata_aligned_bytes)) {
+        LOG(ERROR) << "Unable to align metadata size " << metadata_bytes.size() << " to "
+                   << kSparseAlignment;
+        return {};
+    }
+    metadata_bytes.resize(metadata_aligned_bytes, '\0');
+
+    // However, alignment can cause larger-than-supported metadata blocks. Fall
+    // back to fastbootd/update-super.
+    if (metadata_bytes.size() > metadata->geometry.metadata_max_size) {
+        LOG(VERBOSE) << "Aligned metadata size " << metadata_bytes.size()
+                     << " is larger than maximum metadata size "
+                     << metadata->geometry.metadata_max_size;
+        return {};
+    }
+
+    blob = std::make_shared<std::string>(std::move(metadata_bytes));
+    for (uint32_t i = 0; i < metadata->geometry.metadata_slot_count; i++) {
+        int64_t metadata_primary = GetPrimaryMetadataOffset(metadata->geometry, i);
+        int64_t metadata_backup = GetBackupMetadataOffset(metadata->geometry, i);
+        extents.emplace_back(metadata_primary, blob);
+        extents.emplace_back(metadata_backup, blob);
+    }
+
+    // Add extents for each partition.
+    for (const auto& partition : metadata->partitions) {
+        auto partition_name = GetPartitionName(partition);
+        auto image_name_iter = image_map_.find(partition_name);
+        if (image_name_iter == image_map_.end()) {
+            if (partition.num_extents != 0) {
+                LOG(ERROR) << "Partition " << partition_name
+                           << " has extents but no image filename";
+                return {};
+            }
+            continue;
+        }
+        const auto& image_name = image_name_iter->second;
+
+        uint64_t image_offset = 0;
+        for (uint32_t i = 0; i < partition.num_extents; i++) {
+            const auto& e = metadata->extents[partition.first_extent_index + i];
+
+            if (e.target_type != LP_TARGET_TYPE_LINEAR) {
+                // Any type other than LINEAR isn't understood here. We don't even
+                // bother with ZERO, which is never generated.
+                LOG(INFO) << "Unknown extent type from liblp: " << e.target_type;
+                return {};
+            }
+
+            size_t size = e.num_sectors * LP_SECTOR_SIZE;
+            uint64_t super_offset = e.target_data * LP_SECTOR_SIZE;
+            extents.emplace_back(super_offset, size, image_name, image_offset);
+
+            image_offset += size;
+        }
+    }
+
+    if (!AddGapExtents(&extents, SuperImageExtent::Type::DONTCARE)) {
+        return {};
+    }
+    return extents;
+}
+
+bool SuperImageExtent::operator==(const SuperImageExtent& other) const {
+    if (offset != other.offset) {
+        return false;
+    }
+    if (size != other.size) {
+        return false;
+    }
+    if (type != other.type) {
+        return false;
+    }
+    switch (type) {
+        case Type::DATA:
+            return *blob == *other.blob;
+        case Type::PARTITION:
+            return image_name == other.image_name && image_offset == other.image_offset;
+        default:
+            return true;
+    }
+}
+
+std::ostream& operator<<(std::ostream& stream, const SuperImageExtent& extent) {
+    stream << "extent:" << extent.offset << ":" << extent.size << ":";
+    switch (extent.type) {
+        case SuperImageExtent::Type::DATA:
+            stream << "data";
+            break;
+        case SuperImageExtent::Type::PARTITION:
+            stream << "partition:" << extent.image_name << ":" << extent.image_offset;
+            break;
+        case SuperImageExtent::Type::ZERO:
+            stream << "zero";
+            break;
+        case SuperImageExtent::Type::DONTCARE:
+            stream << "dontcare";
+            break;
+        default:
+            stream << "invalid";
+    }
+    return stream;
+}
+
+}  // namespace fs_mgr
+}  // namespace android
diff --git a/fs_mgr/liblp/super_layout_builder_test.cpp b/fs_mgr/liblp/super_layout_builder_test.cpp
new file mode 100644
index 0000000..714b6b4
--- /dev/null
+++ b/fs_mgr/liblp/super_layout_builder_test.cpp
@@ -0,0 +1,141 @@
+//
+// Copyright (C) 2023 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <liblp/builder.h>
+#include <liblp/super_layout_builder.h>
+#include <storage_literals/storage_literals.h>
+
+#include "images.h"
+#include "writer.h"
+
+using namespace android::fs_mgr;
+using namespace android::storage_literals;
+
+TEST(SuperImageTool, Layout) {
+    auto builder = MetadataBuilder::New(4_MiB, 8_KiB, 2);
+    ASSERT_NE(builder, nullptr);
+
+    Partition* p = builder->AddPartition("system_a", LP_PARTITION_ATTR_READONLY);
+    ASSERT_NE(p, nullptr);
+
+    auto metadata = builder->Export();
+    ASSERT_NE(metadata, nullptr);
+
+    SuperLayoutBuilder tool;
+    ASSERT_TRUE(tool.Open(*metadata.get()));
+    ASSERT_TRUE(tool.AddPartition("system_a", "system.img", 16_KiB));
+
+    // Get a copy of the metadata we'd expect if flashing.
+    ASSERT_TRUE(builder->ResizePartition(p, 16_KiB));
+    metadata = builder->Export();
+    ASSERT_NE(metadata, nullptr);
+
+    auto geometry_blob = std::make_shared<std::string>(SerializeGeometry(metadata->geometry));
+    auto metadata_blob = std::make_shared<std::string>(SerializeMetadata(*metadata.get()));
+    metadata_blob->resize(4_KiB, '\0');
+
+    auto extents = tool.GetImageLayout();
+    ASSERT_EQ(extents.size(), 12);
+    EXPECT_EQ(extents[0], SuperImageExtent(0, 4096, SuperImageExtent::Type::ZERO));
+    EXPECT_EQ(extents[1], SuperImageExtent(4096, geometry_blob));
+    EXPECT_EQ(extents[2], SuperImageExtent(8192, geometry_blob));
+    EXPECT_EQ(extents[3], SuperImageExtent(12288, metadata_blob));
+    EXPECT_EQ(extents[4], SuperImageExtent(16384, 4096, SuperImageExtent::Type::DONTCARE));
+    EXPECT_EQ(extents[5], SuperImageExtent(20480, metadata_blob));
+    EXPECT_EQ(extents[6], SuperImageExtent(24576, 4096, SuperImageExtent::Type::DONTCARE));
+    EXPECT_EQ(extents[7], SuperImageExtent(28672, metadata_blob));
+    EXPECT_EQ(extents[8], SuperImageExtent(32768, 4096, SuperImageExtent::Type::DONTCARE));
+    EXPECT_EQ(extents[9], SuperImageExtent(36864, metadata_blob));
+    EXPECT_EQ(extents[10], SuperImageExtent(40960, 4096, SuperImageExtent::Type::DONTCARE));
+    EXPECT_EQ(extents[11], SuperImageExtent(45056, 16384, "system.img", 0));
+}
+
+TEST(SuperImageTool, NoWritablePartitions) {
+    auto builder = MetadataBuilder::New(4_MiB, 8_KiB, 2);
+    ASSERT_NE(builder, nullptr);
+
+    Partition* p = builder->AddPartition("system_a", 0);
+    ASSERT_NE(p, nullptr);
+
+    auto metadata = builder->Export();
+    ASSERT_NE(metadata, nullptr);
+
+    SuperLayoutBuilder tool;
+    ASSERT_FALSE(tool.Open(*metadata.get()));
+}
+
+TEST(SuperImageTool, NoRetrofit) {
+    auto builder = MetadataBuilder::New(4_MiB, 8_KiB, 2);
+    ASSERT_NE(builder, nullptr);
+
+    Partition* p = builder->AddPartition("system_a", LP_PARTITION_ATTR_READONLY);
+    ASSERT_NE(p, nullptr);
+
+    auto metadata = builder->Export();
+    ASSERT_NE(metadata, nullptr);
+
+    // Add an extra block device.
+    metadata->block_devices.emplace_back(metadata->block_devices[0]);
+
+    SuperLayoutBuilder tool;
+    ASSERT_FALSE(tool.Open(*metadata.get()));
+}
+
+TEST(SuperImageTool, NoRetrofit2) {
+    auto builder = MetadataBuilder::New(4_MiB, 8_KiB, 2);
+    ASSERT_NE(builder, nullptr);
+
+    Partition* p = builder->AddPartition(
+            "system_a", LP_PARTITION_ATTR_READONLY | LP_PARTITION_ATTR_SLOT_SUFFIXED);
+    ASSERT_NE(p, nullptr);
+
+    auto metadata = builder->Export();
+    ASSERT_NE(metadata, nullptr);
+
+    SuperLayoutBuilder tool;
+    ASSERT_FALSE(tool.Open(*metadata.get()));
+}
+
+TEST(SuperImageTool, NoFixedPartitions) {
+    auto builder = MetadataBuilder::New(4_MiB, 8_KiB, 2);
+    ASSERT_NE(builder, nullptr);
+
+    Partition* p = builder->AddPartition("system_a", LP_PARTITION_ATTR_READONLY);
+    ASSERT_NE(p, nullptr);
+    ASSERT_TRUE(builder->ResizePartition(p, 4_KiB));
+
+    auto metadata = builder->Export();
+    ASSERT_NE(metadata, nullptr);
+
+    SuperLayoutBuilder tool;
+    ASSERT_FALSE(tool.Open(*metadata.get()));
+}
+
+TEST(SuperImageTool, LargeAlignedMetadata) {
+    auto builder = MetadataBuilder::New(4_MiB, 512, 2);
+    ASSERT_NE(builder, nullptr);
+
+    auto metadata = builder->Export();
+    ASSERT_NE(metadata, nullptr);
+
+    SuperLayoutBuilder tool;
+    ASSERT_TRUE(tool.Open(*metadata.get()));
+
+    auto extents = tool.GetImageLayout();
+    ASSERT_TRUE(extents.empty());
+}
diff --git a/fs_mgr/liblp/utility.h b/fs_mgr/liblp/utility.h
index aa3a6a0..32a59a5 100644
--- a/fs_mgr/liblp/utility.h
+++ b/fs_mgr/liblp/utility.h
@@ -30,7 +30,7 @@
 
 #include "liblp/liblp.h"
 
-#define LP_TAG "[liblp]"
+#define LP_TAG "[liblp] "
 #define LWARN LOG(WARNING) << LP_TAG
 #define LINFO LOG(INFO) << LP_TAG
 #define LERROR LOG(ERROR) << LP_TAG
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp
index 3932fad..56b48f0 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_writer.cpp
@@ -298,13 +298,12 @@
         return false;
     }
 
-    bool ret = OpenForWrite();
-
-    if (ret) {
-        InitWorkers();
+    if (!OpenForWrite()) {
+        return false;
     }
 
-    return ret;
+    InitWorkers();
+    return true;
 }
 
 bool CowWriter::InitializeAppend(android::base::unique_fd&& fd, uint64_t label) {
diff --git a/fs_mgr/libsnapshot/snapshot_test.cpp b/fs_mgr/libsnapshot/snapshot_test.cpp
index 4014380..13314da 100644
--- a/fs_mgr/libsnapshot/snapshot_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_test.cpp
@@ -2669,44 +2669,46 @@
                                     "Merge"s;
                          });
 
-// Test behavior of ImageManager::Create on low space scenario. These tests assumes image manager
-// uses /data as backup device.
-class ImageManagerTest : public SnapshotTest, public WithParamInterface<uint64_t> {
+class ImageManagerTest : public SnapshotTest {
   protected:
     void SetUp() override {
         SKIP_IF_NON_VIRTUAL_AB();
         SnapshotTest::SetUp();
-        userdata_ = std::make_unique<LowSpaceUserdata>();
-        ASSERT_TRUE(userdata_->Init(GetParam()));
     }
     void TearDown() override {
         RETURN_IF_NON_VIRTUAL_AB();
-
+        CleanUp();
+    }
+    void CleanUp() {
         EXPECT_TRUE(!image_manager_->BackingImageExists(kImageName) ||
                     image_manager_->DeleteBackingImage(kImageName));
     }
+
     static constexpr const char* kImageName = "my_image";
-    std::unique_ptr<LowSpaceUserdata> userdata_;
 };
 
-TEST_P(ImageManagerTest, CreateImageNoSpace) {
-    uint64_t to_allocate = userdata_->free_space() + userdata_->bsize();
-    auto res = image_manager_->CreateBackingImage(kImageName, to_allocate,
-                                                  IImageManager::CREATE_IMAGE_DEFAULT);
-    ASSERT_FALSE(res) << "Should not be able to create image with size = " << to_allocate
-                      << " bytes because only " << userdata_->free_space() << " bytes are free";
-    ASSERT_EQ(FiemapStatus::ErrorCode::NO_SPACE, res.error_code()) << res.string();
-}
-
-std::vector<uint64_t> ImageManagerTestParams() {
-    std::vector<uint64_t> ret;
+TEST_F(ImageManagerTest, CreateImageNoSpace) {
+    bool at_least_one_failure = false;
     for (uint64_t size = 1_MiB; size <= 512_MiB; size *= 2) {
-        ret.push_back(size);
-    }
-    return ret;
-}
+        auto userdata = std::make_unique<LowSpaceUserdata>();
+        ASSERT_TRUE(userdata->Init(size));
 
-INSTANTIATE_TEST_SUITE_P(ImageManagerTest, ImageManagerTest, ValuesIn(ImageManagerTestParams()));
+        uint64_t to_allocate = userdata->free_space() + userdata->bsize();
+
+        auto res = image_manager_->CreateBackingImage(kImageName, to_allocate,
+                                                      IImageManager::CREATE_IMAGE_DEFAULT);
+        if (!res) {
+            at_least_one_failure = true;
+        } else {
+            ASSERT_EQ(res.error_code(), FiemapStatus::ErrorCode::NO_SPACE) << res.string();
+        }
+
+        CleanUp();
+    }
+
+    ASSERT_TRUE(at_least_one_failure)
+            << "We should have failed to allocate at least one over-sized image";
+}
 
 bool Mkdir(const std::string& path) {
     if (mkdir(path.c_str(), 0700) && errno != EEXIST) {
diff --git a/fs_mgr/libsnapshot/snapshot_writer_test.cpp b/fs_mgr/libsnapshot/snapshot_writer_test.cpp
index da48eb9..a03632b 100644
--- a/fs_mgr/libsnapshot/snapshot_writer_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_writer_test.cpp
@@ -33,8 +33,8 @@
     TemporaryFile cow_device_file{};
     android::snapshot::CowOptions options{.block_size = BLOCK_SIZE};
     android::snapshot::CompressedSnapshotWriter snapshot_writer{options};
-    snapshot_writer.SetCowDevice(android::base::unique_fd{cow_device_file.fd});
-    snapshot_writer.Initialize();
+    ASSERT_TRUE(snapshot_writer.SetCowDevice(android::base::unique_fd{cow_device_file.fd}));
+    ASSERT_TRUE(snapshot_writer.Initialize());
     std::vector<unsigned char> buffer;
     buffer.resize(BLOCK_SIZE);
     std::fill(buffer.begin(), buffer.end(), 123);
diff --git a/fs_mgr/libsnapshot/test_helpers.cpp b/fs_mgr/libsnapshot/test_helpers.cpp
index b05123a..9f1d676 100644
--- a/fs_mgr/libsnapshot/test_helpers.cpp
+++ b/fs_mgr/libsnapshot/test_helpers.cpp
@@ -227,7 +227,7 @@
         return AssertionFailure() << "Temp file allocated to " << big_file_->path << ", not in "
                                   << kUserDataDevice;
     }
-    uint64_t next_consume = std::min(available_space_ - max_free_space,
+    uint64_t next_consume = std::min(std::max(available_space_, max_free_space) - max_free_space,
                                      (uint64_t)std::numeric_limits<off_t>::max());
     off_t allocated = 0;
     while (next_consume > 0 && free_space_ > max_free_space) {
diff --git a/fs_mgr/libvbmeta/utility.h b/fs_mgr/libvbmeta/utility.h
index 91db0ad..ab9828d 100644
--- a/fs_mgr/libvbmeta/utility.h
+++ b/fs_mgr/libvbmeta/utility.h
@@ -19,7 +19,7 @@
 #include <android-base/logging.h>
 #include <android-base/result.h>
 
-#define VBMETA_TAG "[libvbmeta]"
+#define VBMETA_TAG "[libvbmeta] "
 #define LWARN LOG(WARNING) << VBMETA_TAG
 #define LINFO LOG(INFO) << VBMETA_TAG
 #define LERROR LOG(ERROR) << VBMETA_TAG
diff --git a/init/OWNERS b/init/OWNERS
index 4604d06..68b9396 100644
--- a/init/OWNERS
+++ b/init/OWNERS
@@ -1,2 +1,3 @@
+# Bug component: 1312227
 dvander@google.com
 jiyong@google.com
diff --git a/init/init.cpp b/init/init.cpp
index 4262191..f964c60 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -952,6 +952,8 @@
     InitKernelLogging(argv);
     LOG(INFO) << "init second stage started!";
 
+    SelinuxSetupKernelLogging();
+
     // Update $PATH in the case the second stage init is newer than first stage init, where it is
     // first set.
     if (setenv("PATH", _PATH_DEFPATH, 1) != 0) {
@@ -1012,7 +1014,6 @@
     MountExtraFilesystems();
 
     // Now set up SELinux for second stage.
-    SelinuxSetupKernelLogging();
     SelabelInitialize();
     SelinuxRestoreContext();
 
diff --git a/init/selinux.cpp b/init/selinux.cpp
index ea308aa..4cc00fe 100644
--- a/init/selinux.cpp
+++ b/init/selinux.cpp
@@ -629,7 +629,7 @@
 }
 
 Result<void> SepolicyFsVerityCheck() {
-    return Error() << "TODO implementent support for fsverity SEPolicy.";
+    return Error() << "TODO implement support for fsverity SEPolicy.";
 }
 
 Result<void> SepolicyCheckSignature(const std::string& dir) {
diff --git a/libcutils/sched_policy_test.cpp b/libcutils/sched_policy_test.cpp
index b9e2832..50bd6d0 100644
--- a/libcutils/sched_policy_test.cpp
+++ b/libcutils/sched_policy_test.cpp
@@ -75,9 +75,11 @@
     }
 
     ASSERT_EQ(0, set_sched_policy(0, SP_BACKGROUND));
+    ASSERT_EQ(0, set_cpuset_policy(0, SP_BACKGROUND));
     AssertPolicy(SP_BACKGROUND);
 
     ASSERT_EQ(0, set_sched_policy(0, SP_FOREGROUND));
+    ASSERT_EQ(0, set_cpuset_policy(0, SP_FOREGROUND));
     AssertPolicy(SP_FOREGROUND);
 }
 
diff --git a/rootdir/Android.mk b/rootdir/Android.mk
index 3dd269a..3362872 100644
--- a/rootdir/Android.mk
+++ b/rootdir/Android.mk
@@ -222,6 +222,8 @@
 LOCAL_SRC_FILES := $(LOCAL_MODULE)
 LOCAL_MODULE_PATH := $(PRODUCT_OUT)
 
+LOCAL_LICENSE_KINDS := SPDX-license-identifier-Apache-2.0
+LOCAL_LICENSE_CONDITIONS := notice
 include $(BUILD_PREBUILT)
 
 include $(call all-makefiles-under,$(LOCAL_PATH))
diff --git a/rootdir/init.rc b/rootdir/init.rc
index db5113f..86c6eaa 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -1288,11 +1288,13 @@
     shutdown critical
 
 on property:ro.debuggable=1
-    # Give writes to anyone for the trace folder on debug builds.
+    # Give writes to the same group for the trace folder on debug builds,
+    # it's further protected by selinux policy.
     # The folder is used to store method traces.
     chmod 0773 /data/misc/trace
-    # Give reads to anyone for the window trace folder on debug builds.
-    chmod 0775 /data/misc/wmtrace
+    # Give writes and reads to anyone for the window trace folder on debug builds,
+    # it's further protected by selinux policy.
+    chmod 0777 /data/misc/wmtrace
     # Give reads to anyone for the accessibility trace folder on debug builds.
     chmod 0775 /data/misc/a11ytrace
 
diff --git a/trusty/storage/proxy/Android.bp b/trusty/storage/proxy/Android.bp
index e952ee0..2e97ee0 100644
--- a/trusty/storage/proxy/Android.bp
+++ b/trusty/storage/proxy/Android.bp
@@ -28,6 +28,7 @@
         "rpmb.c",
         "storage.c",
         "proxy.c",
+        "watchdog.cpp",
     ],
 
     shared_libs: [
diff --git a/trusty/storage/proxy/proxy.c b/trusty/storage/proxy/proxy.c
index 4f77fa2..c89c5b6 100644
--- a/trusty/storage/proxy/proxy.c
+++ b/trusty/storage/proxy/proxy.c
@@ -31,6 +31,7 @@
 #include "log.h"
 #include "rpmb.h"
 #include "storage.h"
+#include "watchdog.h"
 
 #define REQ_BUFFER_SIZE 4096
 static uint8_t req_buffer[REQ_BUFFER_SIZE + 1];
@@ -73,6 +74,8 @@
 static int handle_req(struct storage_msg* msg, const void* req, size_t req_len) {
     int rc;
 
+    struct watcher* watcher = watch_start("request", msg);
+
     if ((msg->flags & STORAGE_MSG_FLAG_POST_COMMIT) && msg->cmd != STORAGE_RPMB_SEND &&
         msg->cmd != STORAGE_FILE_WRITE) {
         /*
@@ -81,14 +84,14 @@
          */
         ALOGE("cmd 0x%x: post commit option is not implemented\n", msg->cmd);
         msg->result = STORAGE_ERR_UNIMPLEMENTED;
-        return ipc_respond(msg, NULL, 0);
+        goto err_response;
     }
 
     if (msg->flags & STORAGE_MSG_FLAG_PRE_COMMIT) {
-        rc = storage_sync_checkpoint();
+        rc = storage_sync_checkpoint(watcher);
         if (rc < 0) {
             msg->result = STORAGE_ERR_SYNC_FAILURE;
-            return ipc_respond(msg, NULL, 0);
+            goto err_response;
         }
     }
 
@@ -99,61 +102,65 @@
         if (rc != 0) {
             ALOGE("is_data_checkpoint_active failed in an unexpected way. Aborting.\n");
             msg->result = STORAGE_ERR_GENERIC;
-            return ipc_respond(msg, NULL, 0);
+            goto err_response;
         } else if (is_checkpoint_active) {
             ALOGE("Checkpoint in progress, dropping write ...\n");
             msg->result = STORAGE_ERR_GENERIC;
-            return ipc_respond(msg, NULL, 0);
+            goto err_response;
         }
     }
 
     switch (msg->cmd) {
         case STORAGE_FILE_DELETE:
-            rc = storage_file_delete(msg, req, req_len);
+            rc = storage_file_delete(msg, req, req_len, watcher);
             break;
 
         case STORAGE_FILE_OPEN:
-            rc = storage_file_open(msg, req, req_len);
+            rc = storage_file_open(msg, req, req_len, watcher);
             break;
 
         case STORAGE_FILE_CLOSE:
-            rc = storage_file_close(msg, req, req_len);
+            rc = storage_file_close(msg, req, req_len, watcher);
             break;
 
         case STORAGE_FILE_WRITE:
-            rc = storage_file_write(msg, req, req_len);
+            rc = storage_file_write(msg, req, req_len, watcher);
             break;
 
         case STORAGE_FILE_READ:
-            rc = storage_file_read(msg, req, req_len);
+            rc = storage_file_read(msg, req, req_len, watcher);
             break;
 
         case STORAGE_FILE_GET_SIZE:
-            rc = storage_file_get_size(msg, req, req_len);
+            rc = storage_file_get_size(msg, req, req_len, watcher);
             break;
 
         case STORAGE_FILE_SET_SIZE:
-            rc = storage_file_set_size(msg, req, req_len);
+            rc = storage_file_set_size(msg, req, req_len, watcher);
             break;
 
         case STORAGE_FILE_GET_MAX_SIZE:
-            rc = storage_file_get_max_size(msg, req, req_len);
+            rc = storage_file_get_max_size(msg, req, req_len, watcher);
             break;
 
         case STORAGE_RPMB_SEND:
-            rc = rpmb_send(msg, req, req_len);
+            rc = rpmb_send(msg, req, req_len, watcher);
             break;
 
         default:
             ALOGE("unhandled command 0x%x\n", msg->cmd);
             msg->result = STORAGE_ERR_UNIMPLEMENTED;
-            rc = 1;
+            goto err_response;
     }
 
-    if (rc > 0) {
-        /* still need to send response */
-        rc = ipc_respond(msg, NULL, 0);
-    }
+    /* response was sent in handler */
+    goto finish;
+
+err_response:
+    rc = ipc_respond(msg, NULL, 0);
+
+finish:
+    watch_finish(watcher);
     return rc;
 }
 
diff --git a/trusty/storage/proxy/rpmb.c b/trusty/storage/proxy/rpmb.c
index b1b8232..22a85a7 100644
--- a/trusty/storage/proxy/rpmb.c
+++ b/trusty/storage/proxy/rpmb.c
@@ -321,7 +321,8 @@
     return SCSI_RES_ERR;
 }
 
-static int send_mmc_rpmb_req(int mmc_fd, const struct storage_rpmb_send_req* req) {
+static int send_mmc_rpmb_req(int mmc_fd, const struct storage_rpmb_send_req* req,
+                             struct watcher* watcher) {
     union {
         struct mmc_ioc_multi_cmd multi;
         uint8_t raw[sizeof(struct mmc_ioc_multi_cmd) + sizeof(struct mmc_ioc_cmd) * 3];
@@ -375,14 +376,17 @@
         cmd++;
     }
 
+    watch_progress(watcher, "rpmb mmc ioctl");
     rc = ioctl(mmc_fd, MMC_IOC_MULTI_CMD, &mmc.multi);
+    watch_progress(watcher, "rpmb mmc ioctl done");
     if (rc < 0) {
         ALOGE("%s: mmc ioctl failed: %d, %s\n", __func__, rc, strerror(errno));
     }
     return rc;
 }
 
-static int send_ufs_rpmb_req(int sg_fd, const struct storage_rpmb_send_req* req) {
+static int send_ufs_rpmb_req(int sg_fd, const struct storage_rpmb_send_req* req,
+                             struct watcher* watcher) {
     int rc;
     int wl_rc;
     const uint8_t* write_buf = req->payload;
@@ -410,7 +414,9 @@
             set_sg_io_hdr(&io_hdr, SG_DXFER_TO_DEV, sizeof(out_cdb), sizeof(sense_buffer),
                           req->reliable_write_size, (void*)write_buf, (unsigned char*)&out_cdb,
                           sense_buffer);
+            watch_progress(watcher, "rpmb ufs reliable write");
             rc = ioctl(sg_fd, SG_IO, &io_hdr);
+            watch_progress(watcher, "rpmb ufs reliable write done");
             if (rc < 0) {
                 ALOGE("%s: ufs ioctl failed: %d, %s\n", __func__, rc, strerror(errno));
                 goto err_op;
@@ -435,7 +441,9 @@
             set_sg_io_hdr(&io_hdr, SG_DXFER_TO_DEV, sizeof(out_cdb), sizeof(sense_buffer),
                           req->write_size, (void*)write_buf, (unsigned char*)&out_cdb,
                           sense_buffer);
+            watch_progress(watcher, "rpmb ufs write");
             rc = ioctl(sg_fd, SG_IO, &io_hdr);
+            watch_progress(watcher, "rpmb ufs write done");
             if (rc < 0) {
                 ALOGE("%s: ufs ioctl failed: %d, %s\n", __func__, rc, strerror(errno));
                 goto err_op;
@@ -450,7 +458,9 @@
         sg_io_hdr_t io_hdr;
         set_sg_io_hdr(&io_hdr, SG_DXFER_FROM_DEV, sizeof(in_cdb), sizeof(sense_buffer),
                       req->read_size, read_buf, (unsigned char*)&in_cdb, sense_buffer);
+        watch_progress(watcher, "rpmb ufs read");
         rc = ioctl(sg_fd, SG_IO, &io_hdr);
+        watch_progress(watcher, "rpmb ufs read done");
         if (rc < 0) {
             ALOGE("%s: ufs ioctl failed: %d, %s\n", __func__, rc, strerror(errno));
         }
@@ -487,7 +497,7 @@
     return rc;
 }
 
-int rpmb_send(struct storage_msg* msg, const void* r, size_t req_len) {
+int rpmb_send(struct storage_msg* msg, const void* r, size_t req_len, struct watcher* watcher) {
     int rc;
     const struct storage_rpmb_send_req* req = r;
 
@@ -523,13 +533,13 @@
     }
 
     if (dev_type == MMC_RPMB) {
-        rc = send_mmc_rpmb_req(rpmb_fd, req);
+        rc = send_mmc_rpmb_req(rpmb_fd, req, watcher);
         if (rc < 0) {
             msg->result = STORAGE_ERR_GENERIC;
             goto err_response;
         }
     } else if (dev_type == UFS_RPMB) {
-        rc = send_ufs_rpmb_req(rpmb_fd, req);
+        rc = send_ufs_rpmb_req(rpmb_fd, req, watcher);
         if (rc < 0) {
             ALOGE("send_ufs_rpmb_req failed: %d, %s\n", rc, strerror(errno));
             msg->result = STORAGE_ERR_GENERIC;
diff --git a/trusty/storage/proxy/rpmb.h b/trusty/storage/proxy/rpmb.h
index f4e1b51..04bdf9a 100644
--- a/trusty/storage/proxy/rpmb.h
+++ b/trusty/storage/proxy/rpmb.h
@@ -18,8 +18,10 @@
 #include <stdint.h>
 #include <trusty/interface/storage.h>
 
+#include "watchdog.h"
+
 enum dev_type { UNKNOWN_RPMB, MMC_RPMB, VIRT_RPMB, UFS_RPMB, SOCK_RPMB };
 
 int rpmb_open(const char* rpmb_devname, enum dev_type dev_type);
-int rpmb_send(struct storage_msg* msg, const void* r, size_t req_len);
+int rpmb_send(struct storage_msg* msg, const void* r, size_t req_len, struct watcher* watcher);
 void rpmb_close(void);
diff --git a/trusty/storage/proxy/storage.c b/trusty/storage/proxy/storage.c
index a96ddcb..2299481 100644
--- a/trusty/storage/proxy/storage.c
+++ b/trusty/storage/proxy/storage.c
@@ -31,6 +31,7 @@
 #include "ipc.h"
 #include "log.h"
 #include "storage.h"
+#include "watchdog.h"
 
 #define FD_TBL_SIZE 64
 #define MAX_READ_SIZE 4096
@@ -180,9 +181,8 @@
     return rcnt;
 }
 
-int storage_file_delete(struct storage_msg *msg,
-                        const void *r, size_t req_len)
-{
+int storage_file_delete(struct storage_msg* msg, const void* r, size_t req_len,
+                        struct watcher* watcher) {
     char *path = NULL;
     const struct storage_file_delete_req *req = r;
 
@@ -208,6 +208,7 @@
         goto err_response;
     }
 
+    watch_progress(watcher, "unlinking file");
     rc = unlink(path);
     if (rc < 0) {
         rc = errno;
@@ -231,8 +232,9 @@
     return ipc_respond(msg, NULL, 0);
 }
 
-static void sync_parent(const char* path) {
+static void sync_parent(const char* path, struct watcher* watcher) {
     int parent_fd;
+    watch_progress(watcher, "syncing parent");
     char* parent_path = dirname(path);
     parent_fd = TEMP_FAILURE_RETRY(open(parent_path, O_RDONLY));
     if (parent_fd >= 0) {
@@ -242,9 +244,11 @@
         ALOGE("%s: failed to open parent directory \"%s\" for sync: %s\n", __func__, parent_path,
               strerror(errno));
     }
+    watch_progress(watcher, "done syncing parent");
 }
 
-int storage_file_open(struct storage_msg* msg, const void* r, size_t req_len) {
+int storage_file_open(struct storage_msg* msg, const void* r, size_t req_len,
+                      struct watcher* watcher) {
     char* path = NULL;
     const struct storage_file_open_req *req = r;
     struct storage_file_open_resp resp = {0};
@@ -306,7 +310,7 @@
             char* parent_path = dirname(path);
             rc = mkdir(parent_path, S_IRWXU);
             if (rc == 0) {
-                sync_parent(parent_path);
+                sync_parent(parent_path, watcher);
             } else if (errno != EEXIST) {
                 ALOGE("%s: Could not create parent directory \"%s\": %s\n", __func__, parent_path,
                       strerror(errno));
@@ -347,7 +351,7 @@
     }
 
     if (open_flags & O_CREAT) {
-        sync_parent(path);
+        sync_parent(path, watcher);
     }
     free(path);
 
@@ -375,9 +379,8 @@
     return ipc_respond(msg, NULL, 0);
 }
 
-int storage_file_close(struct storage_msg *msg,
-                       const void *r, size_t req_len)
-{
+int storage_file_close(struct storage_msg* msg, const void* r, size_t req_len,
+                       struct watcher* watcher) {
     const struct storage_file_close_req *req = r;
 
     if (req_len != sizeof(*req)) {
@@ -390,7 +393,9 @@
     int fd = remove_fd(req->handle);
     ALOGV("%s: handle = %u: fd = %u\n", __func__, req->handle, fd);
 
+    watch_progress(watcher, "fsyncing before file close");
     int rc = fsync(fd);
+    watch_progress(watcher, "done fsyncing before file close");
     if (rc < 0) {
         rc = errno;
         ALOGE("%s: fsync failed for fd=%u: %s\n",
@@ -414,10 +419,8 @@
     return ipc_respond(msg, NULL, 0);
 }
 
-
-int storage_file_write(struct storage_msg *msg,
-                       const void *r, size_t req_len)
-{
+int storage_file_write(struct storage_msg* msg, const void* r, size_t req_len,
+                       struct watcher* watcher) {
     int rc;
     const struct storage_file_write_req *req = r;
 
@@ -429,17 +432,20 @@
     }
 
     int fd = lookup_fd(req->handle, true);
+    watch_progress(watcher, "writing");
     if (write_with_retry(fd, &req->data[0], req_len - sizeof(*req),
                          req->offset) < 0) {
+        watch_progress(watcher, "writing done w/ error");
         rc = errno;
         ALOGW("%s: error writing file (fd=%d): %s\n",
               __func__, fd, strerror(errno));
         msg->result = translate_errno(rc);
         goto err_response;
     }
+    watch_progress(watcher, "writing done");
 
     if (msg->flags & STORAGE_MSG_FLAG_POST_COMMIT) {
-        rc = storage_sync_checkpoint();
+        rc = storage_sync_checkpoint(watcher);
         if (rc < 0) {
             msg->result = STORAGE_ERR_SYNC_FAILURE;
             goto err_response;
@@ -452,10 +458,8 @@
     return ipc_respond(msg, NULL, 0);
 }
 
-
-int storage_file_read(struct storage_msg *msg,
-                      const void *r, size_t req_len)
-{
+int storage_file_read(struct storage_msg* msg, const void* r, size_t req_len,
+                      struct watcher* watcher) {
     int rc;
     const struct storage_file_read_req *req = r;
 
@@ -474,8 +478,10 @@
     }
 
     int fd = lookup_fd(req->handle, false);
+    watch_progress(watcher, "reading");
     ssize_t read_res = read_with_retry(fd, read_rsp.hdr.data, req->size,
                                        (off_t)req->offset);
+    watch_progress(watcher, "reading done");
     if (read_res < 0) {
         rc = errno;
         ALOGW("%s: error reading file (fd=%d): %s\n",
@@ -491,10 +497,8 @@
     return ipc_respond(msg, NULL, 0);
 }
 
-
-int storage_file_get_size(struct storage_msg *msg,
-                          const void *r, size_t req_len)
-{
+int storage_file_get_size(struct storage_msg* msg, const void* r, size_t req_len,
+                          struct watcher* watcher) {
     const struct storage_file_get_size_req *req = r;
     struct storage_file_get_size_resp resp = {0};
 
@@ -507,7 +511,9 @@
 
     struct stat stat;
     int fd = lookup_fd(req->handle, false);
+    watch_progress(watcher, "fstat");
     int rc = fstat(fd, &stat);
+    watch_progress(watcher, "fstat done");
     if (rc < 0) {
         rc = errno;
         ALOGE("%s: error stat'ing file (fd=%d): %s\n",
@@ -524,10 +530,8 @@
     return ipc_respond(msg, NULL, 0);
 }
 
-
-int storage_file_set_size(struct storage_msg *msg,
-                          const void *r, size_t req_len)
-{
+int storage_file_set_size(struct storage_msg* msg, const void* r, size_t req_len,
+                          struct watcher* watcher) {
     const struct storage_file_set_size_req *req = r;
 
     if (req_len != sizeof(*req)) {
@@ -538,7 +542,9 @@
     }
 
     int fd = lookup_fd(req->handle, true);
+    watch_progress(watcher, "ftruncate");
     int rc = TEMP_FAILURE_RETRY(ftruncate(fd, req->size));
+    watch_progress(watcher, "ftruncate done");
     if (rc < 0) {
         rc = errno;
         ALOGE("%s: error truncating file (fd=%d): %s\n",
@@ -553,7 +559,8 @@
     return ipc_respond(msg, NULL, 0);
 }
 
-int storage_file_get_max_size(struct storage_msg* msg, const void* r, size_t req_len) {
+int storage_file_get_max_size(struct storage_msg* msg, const void* r, size_t req_len,
+                              struct watcher* watcher) {
     const struct storage_file_get_max_size_req* req = r;
     struct storage_file_get_max_size_resp resp = {0};
     uint64_t max_size = 0;
@@ -566,7 +573,9 @@
 
     struct stat stat;
     int fd = lookup_fd(req->handle, false);
+    watch_progress(watcher, "fstat to get max size");
     int rc = fstat(fd, &stat);
+    watch_progress(watcher, "fstat to get max size done");
     if (rc < 0) {
         ALOGE("%s: error stat'ing file (fd=%d): %s\n", __func__, fd, strerror(errno));
         goto err_response;
@@ -606,10 +615,10 @@
     return 0;
 }
 
-int storage_sync_checkpoint(void)
-{
+int storage_sync_checkpoint(struct watcher* watcher) {
     int rc;
 
+    watch_progress(watcher, "sync fd table");
     /* sync fd table and reset it to clean state first */
     for (uint fd = 0; fd < FD_TBL_SIZE; fd++) {
          if (fd_state[fd] == SS_DIRTY) {
@@ -634,10 +643,12 @@
          * because our fd table is large enough to handle the few open files we
          * use.
          */
-        sync();
-        fs_state = SS_CLEAN;
+         watch_progress(watcher, "all fs sync");
+         sync();
+         fs_state = SS_CLEAN;
     }
 
+    watch_progress(watcher, "done syncing");
+
     return 0;
 }
-
diff --git a/trusty/storage/proxy/storage.h b/trusty/storage/proxy/storage.h
index 77bfa13..f29fdf2 100644
--- a/trusty/storage/proxy/storage.h
+++ b/trusty/storage/proxy/storage.h
@@ -18,30 +18,33 @@
 #include <stdint.h>
 #include <trusty/interface/storage.h>
 
-int storage_file_delete(struct storage_msg *msg,
-                        const void *req, size_t req_len);
+/* Defined in watchdog.h */
+struct watcher;
 
-int storage_file_open(struct storage_msg *msg,
-                      const void *req, size_t req_len);
+int storage_file_delete(struct storage_msg* msg, const void* req, size_t req_len,
+                        struct watcher* watcher);
 
-int storage_file_close(struct storage_msg *msg,
-                       const void *req, size_t req_len);
+int storage_file_open(struct storage_msg* msg, const void* req, size_t req_len,
+                      struct watcher* watcher);
 
-int storage_file_write(struct storage_msg *msg,
-                       const void *req, size_t req_len);
+int storage_file_close(struct storage_msg* msg, const void* req, size_t req_len,
+                       struct watcher* watcher);
 
-int storage_file_read(struct storage_msg *msg,
-                      const void *req, size_t req_len);
+int storage_file_write(struct storage_msg* msg, const void* req, size_t req_len,
+                       struct watcher* watcher);
 
-int storage_file_get_size(struct storage_msg *msg,
-                          const void *req, size_t req_len);
+int storage_file_read(struct storage_msg* msg, const void* req, size_t req_len,
+                      struct watcher* watcher);
 
-int storage_file_set_size(struct storage_msg *msg,
-                          const void *req, size_t req_len);
+int storage_file_get_size(struct storage_msg* msg, const void* req, size_t req_len,
+                          struct watcher* watcher);
 
-int storage_file_get_max_size(struct storage_msg* msg, const void* req, size_t req_len);
+int storage_file_set_size(struct storage_msg* msg, const void* req, size_t req_len,
+                          struct watcher* watcher);
 
-int storage_init(const char *dirname);
+int storage_file_get_max_size(struct storage_msg* msg, const void* req, size_t req_len,
+                              struct watcher* watcher);
 
-int storage_sync_checkpoint(void);
+int storage_init(const char* dirname);
 
+int storage_sync_checkpoint(struct watcher* watcher);
diff --git a/trusty/storage/proxy/watchdog.cpp b/trusty/storage/proxy/watchdog.cpp
new file mode 100644
index 0000000..6c09e26
--- /dev/null
+++ b/trusty/storage/proxy/watchdog.cpp
@@ -0,0 +1,208 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "watchdog.h"
+
+#include <chrono>
+#include <cstdint>
+#include <optional>
+#include <thread>
+#include <vector>
+
+#include <android-base/logging.h>
+
+struct watcher {
+    watcher(const char* id, const struct storage_msg* request);
+    void SetState(const char* new_state);
+    void LogTimeout();
+    void LogFinished();
+
+    const char* id_;
+    uint32_t cmd_;
+    uint32_t op_id_;
+    uint32_t flags_;
+    const char* state_;
+
+    using clock = std::chrono::high_resolution_clock;
+    clock::time_point start_;
+    clock::time_point state_change_;
+    std::chrono::milliseconds Elapsed(clock::time_point end);
+
+    bool triggered_;
+};
+
+watcher::watcher(const char* id, const struct storage_msg* request)
+    : id_(id), state_(nullptr), triggered_(false) {
+    cmd_ = request->cmd;
+    op_id_ = request->op_id;
+    flags_ = request->flags;
+
+    start_ = clock::now();
+    state_change_ = start_;
+}
+
+void watcher::SetState(const char* new_state) {
+    state_ = new_state;
+    state_change_ = clock::now();
+}
+
+void watcher::LogTimeout() {
+    if (!triggered_) {
+        triggered_ = true;
+        LOG(ERROR) << "Storageproxyd watchdog triggered: " << id_ << " cmd: " << cmd_
+                   << " op_id: " << op_id_ << " flags: " << flags_;
+    }
+    if (state_) {
+        LOG(ERROR) << "...elapsed: " << Elapsed(clock::now()).count() << "ms (" << state_ << " "
+                   << Elapsed(state_change_).count() << "ms)";
+    } else {
+        LOG(ERROR) << "...elapsed: " << Elapsed(clock::now()).count() << "ms";
+    }
+}
+
+void watcher::LogFinished() {
+    if (triggered_) {
+        LOG(ERROR) << "...completed: " << Elapsed(clock::now()).count() << "ms";
+    }
+}
+
+std::chrono::milliseconds watcher::Elapsed(watcher::clock::time_point end) {
+    return std::chrono::duration_cast<std::chrono::milliseconds>(end - start_);
+}
+
+namespace {
+
+class Watchdog {
+  private:
+    static constexpr std::chrono::milliseconds kDefaultTimeoutMs = std::chrono::milliseconds(500);
+    static constexpr std::chrono::milliseconds kMaxTimeoutMs = std::chrono::seconds(10);
+
+  public:
+    Watchdog() : watcher_(), done_(false) {}
+    ~Watchdog();
+    struct watcher* RegisterWatch(const char* id, const struct storage_msg* request);
+    void AddProgress(struct watcher* watcher, const char* state);
+    void UnRegisterWatch(struct watcher* watcher);
+
+  private:
+    // Syncronizes access to watcher_ and watcher_change_ between the main
+    // thread and watchdog loop thread. watcher_ may only be modified by the
+    // main thread; the watchdog loop is read-only.
+    std::mutex watcher_mutex_;
+    std::unique_ptr<struct watcher> watcher_;
+    std::condition_variable watcher_change_;
+
+    std::thread watchdog_thread_;
+    bool done_;
+
+    void WatchdogLoop();
+    void LogWatchdogTriggerLocked();
+};
+
+Watchdog gWatchdog;
+
+}  // Anonymous namespace
+
+// Assumes that caller is single-threaded. If we want to use this from a
+// multi-threaded context we need to ensure that the watchdog thread is
+// initialized safely once and accessing an existing watcher is done while the
+// watcher lock is held.
+struct watcher* Watchdog::RegisterWatch(const char* id, const struct storage_msg* request) {
+    if (!watchdog_thread_.joinable()) {
+        watchdog_thread_ = std::thread(&Watchdog::WatchdogLoop, this);
+    }
+    if (watcher_) {
+        LOG(ERROR) << "Replacing registered watcher " << watcher_->id_;
+        UnRegisterWatch(watcher_.get());
+    }
+
+    struct watcher* ret = nullptr;
+    {
+        std::unique_lock<std::mutex> watcherLock(watcher_mutex_);
+        watcher_ = std::make_unique<struct watcher>(id, request);
+        ret = watcher_.get();
+    }
+    watcher_change_.notify_one();
+    return ret;
+}
+
+void Watchdog::UnRegisterWatch(struct watcher* watcher) {
+    {
+        std::lock_guard<std::mutex> watcherLock(watcher_mutex_);
+        if (!watcher_) {
+            LOG(ERROR) << "Cannot unregister watcher, no watcher registered";
+            return;
+        }
+        if (watcher_.get() != watcher) {
+            LOG(ERROR) << "Unregistering watcher that doesn't match current watcher";
+        }
+        watcher_->LogFinished();
+        watcher_.reset(nullptr);
+    }
+    watcher_change_.notify_one();
+}
+
+void Watchdog::AddProgress(struct watcher* watcher, const char* state) {
+    std::lock_guard<std::mutex> watcherLock(watcher_mutex_);
+    if (watcher_.get() != watcher) {
+        LOG(ERROR) << "Watcher was not registered, cannot log progress: " << state;
+        return;
+    }
+    watcher->SetState(state);
+}
+
+void Watchdog::WatchdogLoop() {
+    std::unique_lock<std::mutex> lock(watcher_mutex_);
+    std::chrono::milliseconds timeout = kDefaultTimeoutMs;
+
+    while (!done_) {
+        // wait for a watch to be registered
+        watcher_change_.wait(lock, [this] { return !!watcher_; });
+
+        // wait for the timeout or unregistration
+        timeout = kDefaultTimeoutMs;
+        do {
+            if (!watcher_change_.wait_for(lock, timeout, [this] { return !watcher_; })) {
+                watcher_->LogTimeout();
+                timeout = std::min(timeout * 2, kMaxTimeoutMs);
+            }
+        } while (!!watcher_);
+    }
+}
+
+Watchdog::~Watchdog() {
+    {
+        std::lock_guard<std::mutex> watcherLock(watcher_mutex_);
+        watcher_.reset(nullptr);
+        done_ = true;
+    }
+    watcher_change_.notify_one();
+    if (watchdog_thread_.joinable()) {
+        watchdog_thread_.join();
+    }
+}
+
+struct watcher* watch_start(const char* id, const struct storage_msg* request) {
+    return gWatchdog.RegisterWatch(id, request);
+}
+
+void watch_progress(struct watcher* watcher, const char* state) {
+    gWatchdog.AddProgress(watcher, state);
+}
+
+void watch_finish(struct watcher* watcher) {
+    gWatchdog.UnRegisterWatch(watcher);
+}
diff --git a/trusty/storage/proxy/watchdog.h b/trusty/storage/proxy/watchdog.h
new file mode 100644
index 0000000..9162fcb
--- /dev/null
+++ b/trusty/storage/proxy/watchdog.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "storage.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct watcher;
+
+/**
+ * watch_start() - Create a watcher for a storage request
+ * @id:        Identifier string to distinguish watchers
+ * @request:   Incoming request from Trusty storage service
+ *
+ * Create a watcher that will start logging if not finished before a timeout.
+ * Only one watcher may be active at a time, and this function may only be
+ * called from a single thread.
+ */
+struct watcher* watch_start(const char* id, const struct storage_msg* request);
+
+/**
+ * watch_progress() - Note progress on servicing the current request
+ * @watcher:   Current watcher, created by watch()
+ *
+ * Sets the current progress state of the watcher, to allow for more granular
+ * reporting of what exactly is stuck if the timeout is reached.
+ */
+void watch_progress(struct watcher* watcher, const char* state);
+
+/**
+ * watch_finish() - Finish watching and unregister the watch
+ * @watcher:   Current watcher, created by watch(). Takes ownership of this pointer.
+ *
+ * Finish the current watch task. This function takes ownership of the watcher
+ * and destroys it, so @watcher must not be used again after calling this
+ * function.
+ */
+void watch_finish(struct watcher* watcher);
+
+#ifdef __cplusplus
+}
+#endif