Update contrib/restricted/abseil-cpp to 20220623.0

19 files changed, 412 insertions, 238 deletions

diff --git a/contrib/restricted/abseil-cpp/absl/debugging/CMakeLists.txt b/contrib/restricted/abseil-cpp/absl/debugging/CMakeLists.txt
index e1c83366768..6dbbe449586 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/CMakeLists.txt
+++ b/contrib/restricted/abseil-cpp/absl/debugging/CMakeLists.txt
@@ -26,7 +26,6 @@ target_sources(abseil-cpp-absl-debugging PRIVATE
   ${CMAKE_SOURCE_DIR}/contrib/restricted/abseil-cpp/absl/debugging/internal/examine_stack.cc
   ${CMAKE_SOURCE_DIR}/contrib/restricted/abseil-cpp/absl/debugging/internal/vdso_support.cc
   ${CMAKE_SOURCE_DIR}/contrib/restricted/abseil-cpp/absl/debugging/leak_check.cc
-  ${CMAKE_SOURCE_DIR}/contrib/restricted/abseil-cpp/absl/debugging/leak_check_disable.cc
   ${CMAKE_SOURCE_DIR}/contrib/restricted/abseil-cpp/absl/debugging/stacktrace.cc
   ${CMAKE_SOURCE_DIR}/contrib/restricted/abseil-cpp/absl/debugging/symbolize.cc
 )
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/failure_signal_handler.cc b/contrib/restricted/abseil-cpp/absl/debugging/failure_signal_handler.cc
index 689e5979e77..affade3b66b 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/failure_signal_handler.cc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/failure_signal_handler.cc
@@ -42,7 +42,6 @@
 #include <ctime>
 
 #include "absl/base/attributes.h"
-#include "absl/base/internal/errno_saver.h"
 #include "absl/base/internal/raw_logging.h"
 #include "absl/base/internal/sysinfo.h"
 #include "absl/debugging/internal/examine_stack.h"
@@ -52,7 +51,7 @@
 #define ABSL_HAVE_SIGACTION
 // Apple WatchOS and TVOS don't allow sigaltstack
 #if !(defined(TARGET_OS_WATCH) && TARGET_OS_WATCH) && \
-    !(defined(TARGET_OS_TV) && TARGET_OS_TV)
+    !(defined(TARGET_OS_TV) && TARGET_OS_TV) && !defined(__QNX__)
 #define ABSL_HAVE_SIGALTSTACK
 #endif
 #endif
@@ -217,8 +216,7 @@ static void InstallOneFailureHandler(FailureSignalData* data,
 #endif
 
 static void WriteToStderr(const char* data) {
-  absl::base_internal::ErrnoSaver errno_saver;
-  absl::raw_logging_internal::SafeWriteToStderr(data, strlen(data));
+  absl::raw_logging_internal::AsyncSignalSafeWriteToStderr(data, strlen(data));
 }
 
 static void WriteSignalMessage(int signo, int cpu,
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/address_is_readable.cc b/contrib/restricted/abseil-cpp/absl/debugging/internal/address_is_readable.cc
index 329c285f3b5..4be6256bfb0 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/address_is_readable.cc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/address_is_readable.cc
@@ -30,16 +30,12 @@ bool AddressIsReadable(const void* /* addr */) { return true; }
 ABSL_NAMESPACE_END
 }  // namespace absl
 
-#else
+#else  // __linux__ && !__ANDROID__
 
-#include <fcntl.h>
-#include <sys/syscall.h>
+#include <stdint.h>
+#include <syscall.h>
 #include <unistd.h>
 
-#include <atomic>
-#include <cerrno>
-#include <cstdint>
-
 #include "absl/base/internal/errno_saver.h"
 #include "absl/base/internal/raw_logging.h"
 
@@ -47,93 +43,54 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
-// Pack a pid and two file descriptors into a 64-bit word,
-// using 16, 24, and 24 bits for each respectively.
-static uint64_t Pack(uint64_t pid, uint64_t read_fd, uint64_t write_fd) {
-  ABSL_RAW_CHECK((read_fd >> 24) == 0 && (write_fd >> 24) == 0,
-                 "fd out of range");
-  return (pid << 48) | ((read_fd & 0xffffff) << 24) | (write_fd & 0xffffff);
-}
-
-// Unpack x into a pid and two file descriptors, where x was created with
-// Pack().
-static void Unpack(uint64_t x, int *pid, int *read_fd, int *write_fd) {
-  *pid = x >> 48;
-  *read_fd = (x >> 24) & 0xffffff;
-  *write_fd = x & 0xffffff;
-}
+// NOTE: be extra careful about adding any interposable function calls here
+// (such as open(), read(), etc.). These symbols may be interposed and will get
+// invoked in contexts they don't expect.
+//
+// NOTE: any new system calls here may also require sandbox reconfiguration.
+//
+bool AddressIsReadable(const void *addr) {
+  // Align address on 8-byte boundary. On aarch64, checking last
+  // byte before inaccessible page returned unexpected EFAULT.
+  const uintptr_t u_addr = reinterpret_cast<uintptr_t>(addr) & ~7;
+  addr = reinterpret_cast<const void *>(u_addr);
 
-// Return whether the byte at *addr is readable, without faulting.
-// Save and restores errno.   Returns true on systems where
-// unimplemented.
-// This is a namespace-scoped variable for correct zero-initialization.
-static std::atomic<uint64_t> pid_and_fds;  // initially 0, an invalid pid.
+  // rt_sigprocmask below will succeed for this input.
+  if (addr == nullptr) return false;
 
-bool AddressIsReadable(const void *addr) {
   absl::base_internal::ErrnoSaver errno_saver;
-  // We test whether a byte is readable by using write().  Normally, this would
-  // be done via a cached file descriptor to /dev/null, but linux fails to
-  // check whether the byte is readable when the destination is /dev/null, so
-  // we use a cached pipe.  We store the pid of the process that created the
-  // pipe to handle the case where a process forks, and the child closes all
-  // the file descriptors and then calls this routine.  This is not perfect:
-  // the child could use the routine, then close all file descriptors and then
-  // use this routine again.  But the likely use of this routine is when
-  // crashing, to test the validity of pages when dumping the stack.  Beware
-  // that we may leak file descriptors, but we're unlikely to leak many.
-  int bytes_written;
-  int current_pid = getpid() & 0xffff;   // we use only the low order 16 bits
-  do {  // until we do not get EBADF trying to use file descriptors
-    int pid;
-    int read_fd;
-    int write_fd;
-    uint64_t local_pid_and_fds = pid_and_fds.load(std::memory_order_acquire);
-    Unpack(local_pid_and_fds, &pid, &read_fd, &write_fd);
-    while (current_pid != pid) {
-      int p[2];
-      // new pipe
-      if (pipe(p) != 0) {
-        ABSL_RAW_LOG(FATAL, "Failed to create pipe, errno=%d", errno);
-      }
-      fcntl(p[0], F_SETFD, FD_CLOEXEC);
-      fcntl(p[1], F_SETFD, FD_CLOEXEC);
-      uint64_t new_pid_and_fds = Pack(current_pid, p[0], p[1]);
-      if (pid_and_fds.compare_exchange_strong(
-              local_pid_and_fds, new_pid_and_fds, std::memory_order_release,
-              std::memory_order_relaxed)) {
-        local_pid_and_fds = new_pid_and_fds;  // fds exposed to other threads
-      } else {  // fds not exposed to other threads; we can close them.
-        close(p[0]);
-        close(p[1]);
-        local_pid_and_fds = pid_and_fds.load(std::memory_order_acquire);
-      }
-      Unpack(local_pid_and_fds, &pid, &read_fd, &write_fd);
-    }
-    errno = 0;
-    // Use syscall(SYS_write, ...) instead of write() to prevent ASAN
-    // and other checkers from complaining about accesses to arbitrary
-    // memory.
-    do {
-      bytes_written = syscall(SYS_write, write_fd, addr, 1);
-    } while (bytes_written == -1 && errno == EINTR);
-    if (bytes_written == 1) {   // remove the byte from the pipe
-      char c;
-      while (read(read_fd, &c, 1) == -1 && errno == EINTR) {
-      }
-    }
-    if (errno == EBADF) {  // Descriptors invalid.
-      // If pid_and_fds contains the problematic file descriptors we just used,
-      // this call will forget them, and the loop will try again.
-      pid_and_fds.compare_exchange_strong(local_pid_and_fds, 0,
-                                          std::memory_order_release,
-                                          std::memory_order_relaxed);
-    }
-  } while (errno == EBADF);
-  return bytes_written == 1;
+
+  // Here we probe with some syscall which
+  // - accepts an 8-byte region of user memory as input
+  // - tests for EFAULT before other validation
+  // - has no problematic side-effects
+  //
+  // rt_sigprocmask(2) works for this.  It copies sizeof(kernel_sigset_t)==8
+  // bytes from the address into the kernel memory before any validation.
+  //
+  // The call can never succeed, since the `how` parameter is not one of
+  // SIG_BLOCK, SIG_UNBLOCK, SIG_SETMASK.
+  //
+  // This strategy depends on Linux implementation details,
+  // so we rely on the test to alert us if it stops working.
+  //
+  // Some discarded past approaches:
+  // - msync() doesn't reject PROT_NONE regions
+  // - write() on /dev/null doesn't return EFAULT
+  // - write() on a pipe requires creating it and draining the writes
+  // - connect() works but is problematic for sandboxes and needs a valid
+  //   file descriptor
+  //
+  // This can never succeed (invalid first argument to sigprocmask).
+  ABSL_RAW_CHECK(syscall(SYS_rt_sigprocmask, ~0, addr, nullptr,
+                         /*sizeof(kernel_sigset_t)*/ 8) == -1,
+                 "unexpected success");
+  ABSL_RAW_CHECK(errno == EFAULT || errno == EINVAL, "unexpected errno");
+  return errno != EFAULT;
 }
 
 }  // namespace debugging_internal
 ABSL_NAMESPACE_END
 }  // namespace absl
 
-#endif
+#endif  // __linux__ && !__ANDROID__
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/elf_mem_image.cc b/contrib/restricted/abseil-cpp/absl/debugging/internal/elf_mem_image.cc
index 29a281812bc..a9d667143a5 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/elf_mem_image.cc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/elf_mem_image.cc
@@ -351,7 +351,11 @@ void ElfMemImage::SymbolIterator::Update(int increment) {
   const ElfW(Versym) *version_symbol = image->GetVersym(index_);
   ABSL_RAW_CHECK(symbol && version_symbol, "");
   const char *const symbol_name = image->GetDynstr(symbol->st_name);
+#if defined(__NetBSD__)
+  const int version_index = version_symbol->vs_vers & VERSYM_VERSION;
+#else
   const ElfW(Versym) version_index = version_symbol[0] & VERSYM_VERSION;
+#endif
   const ElfW(Verdef) *version_definition = nullptr;
   const char *version_name = "";
   if (symbol->st_shndx == SHN_UNDEF) {
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/elf_mem_image.h b/contrib/restricted/abseil-cpp/absl/debugging/internal/elf_mem_image.h
index a894bd423e8..113071a9d19 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/elf_mem_image.h
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/elf_mem_image.h
@@ -31,8 +31,9 @@
 #error ABSL_HAVE_ELF_MEM_IMAGE cannot be directly set
 #endif
 
-#if defined(__ELF__) && !defined(__native_client__) && !defined(__asmjs__) && \
-    !defined(__wasm__)
+#if defined(__ELF__) && !defined(__OpenBSD__) && !defined(__QNX__) && \
+    !defined(__native_client__) && !defined(__asmjs__) &&             \
+    !defined(__wasm__) && !defined(__HAIKU__)
 #define ABSL_HAVE_ELF_MEM_IMAGE 1
 #endif
 
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/examine_stack.cc b/contrib/restricted/abseil-cpp/absl/debugging/internal/examine_stack.cc
index 589a3ef367d..5bdd341e1ba 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/examine_stack.cc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/examine_stack.cc
@@ -20,7 +20,13 @@
 #include <unistd.h>
 #endif
 
-#ifdef __APPLE__
+#include "absl/base/config.h"
+
+#ifdef ABSL_HAVE_MMAP
+#include <sys/mman.h>
+#endif
+
+#if defined(__linux__) || defined(__APPLE__)
 #include <sys/ucontext.h>
 #endif
 
@@ -37,10 +43,115 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
+namespace {
+constexpr int kDefaultDumpStackFramesLimit = 64;
+// The %p field width for printf() functions is two characters per byte,
+// and two extra for the leading "0x".
+constexpr int kPrintfPointerFieldWidth = 2 + 2 * sizeof(void*);
+
+ABSL_CONST_INIT SymbolizeUrlEmitter debug_stack_trace_hook = nullptr;
+
+// Async-signal safe mmap allocator.
+void* Allocate(size_t num_bytes) {
+#ifdef ABSL_HAVE_MMAP
+  void* p = ::mmap(nullptr, num_bytes, PROT_READ | PROT_WRITE,
+                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  return p == MAP_FAILED ? nullptr : p;
+#else
+  (void)num_bytes;
+  return nullptr;
+#endif  // ABSL_HAVE_MMAP
+}
+
+void Deallocate(void* p, size_t size) {
+#ifdef ABSL_HAVE_MMAP
+  ::munmap(p, size);
+#else
+  (void)p;
+  (void)size;
+#endif  // ABSL_HAVE_MMAP
+}
+
+// Print a program counter only.
+void DumpPC(OutputWriter* writer, void* writer_arg, void* const pc,
+            const char* const prefix) {
+  char buf[100];
+  snprintf(buf, sizeof(buf), "%s@ %*p\n", prefix, kPrintfPointerFieldWidth, pc);
+  writer(buf, writer_arg);
+}
+
+// Print a program counter and the corresponding stack frame size.
+void DumpPCAndFrameSize(OutputWriter* writer, void* writer_arg, void* const pc,
+                        int framesize, const char* const prefix) {
+  char buf[100];
+  if (framesize <= 0) {
+    snprintf(buf, sizeof(buf), "%s@ %*p  (unknown)\n", prefix,
+             kPrintfPointerFieldWidth, pc);
+  } else {
+    snprintf(buf, sizeof(buf), "%s@ %*p  %9d\n", prefix,
+             kPrintfPointerFieldWidth, pc, framesize);
+  }
+  writer(buf, writer_arg);
+}
+
+// Print a program counter and the corresponding symbol.
+void DumpPCAndSymbol(OutputWriter* writer, void* writer_arg, void* const pc,
+                     const char* const prefix) {
+  char tmp[1024];
+  const char* symbol = "(unknown)";
+  // Symbolizes the previous address of pc because pc may be in the
+  // next function.  The overrun happens when the function ends with
+  // a call to a function annotated noreturn (e.g. CHECK).
+  // If symbolization of pc-1 fails, also try pc on the off-chance
+  // that we crashed on the first instruction of a function (that
+  // actually happens very often for e.g. __restore_rt).
+  const uintptr_t prev_pc = reinterpret_cast<uintptr_t>(pc) - 1;
+  if (absl::Symbolize(reinterpret_cast<const char*>(prev_pc), tmp,
+                      sizeof(tmp)) ||
+      absl::Symbolize(pc, tmp, sizeof(tmp))) {
+    symbol = tmp;
+  }
+  char buf[1024];
+  snprintf(buf, sizeof(buf), "%s@ %*p  %s\n", prefix, kPrintfPointerFieldWidth,
+           pc, symbol);
+  writer(buf, writer_arg);
+}
+
+// Print a program counter, its stack frame size, and its symbol name.
+// Note that there is a separate symbolize_pc argument. Return addresses may be
+// at the end of the function, and this allows the caller to back up from pc if
+// appropriate.
+void DumpPCAndFrameSizeAndSymbol(OutputWriter* writer, void* writer_arg,
+                                 void* const pc, void* const symbolize_pc,
+                                 int framesize, const char* const prefix) {
+  char tmp[1024];
+  const char* symbol = "(unknown)";
+  if (absl::Symbolize(symbolize_pc, tmp, sizeof(tmp))) {
+    symbol = tmp;
+  }
+  char buf[1024];
+  if (framesize <= 0) {
+    snprintf(buf, sizeof(buf), "%s@ %*p  (unknown)  %s\n", prefix,
+             kPrintfPointerFieldWidth, pc, symbol);
+  } else {
+    snprintf(buf, sizeof(buf), "%s@ %*p  %9d  %s\n", prefix,
+             kPrintfPointerFieldWidth, pc, framesize, symbol);
+  }
+  writer(buf, writer_arg);
+}
+
+}  // namespace
+
+void RegisterDebugStackTraceHook(SymbolizeUrlEmitter hook) {
+  debug_stack_trace_hook = hook;
+}
+
+SymbolizeUrlEmitter GetDebugStackTraceHook() { return debug_stack_trace_hook; }
+
 // Returns the program counter from signal context, nullptr if
 // unknown. vuc is a ucontext_t*. We use void* to avoid the use of
 // ucontext_t on non-POSIX systems.
-void* GetProgramCounter(void* vuc) {
+void* GetProgramCounter(void* const vuc) {
 #ifdef __linux__
   if (vuc != nullptr) {
     ucontext_t* context = reinterpret_cast<ucontext_t*>(vuc);
@@ -82,6 +193,8 @@ void* GetProgramCounter(void* vuc) {
       return reinterpret_cast<void*>(context->uc_mcontext.gregs[16]);
 #elif defined(__e2k__)
     return reinterpret_cast<void*>(context->uc_mcontext.cr0_hi);
+#elif defined(__loongarch__)
+    return reinterpret_cast<void*>(context->uc_mcontext.__pc);
 #else
 #error "Undefined Architecture."
 #endif
@@ -120,59 +233,17 @@ void* GetProgramCounter(void* vuc) {
   return nullptr;
 }
 
-// The %p field width for printf() functions is two characters per byte,
-// and two extra for the leading "0x".
-static constexpr int kPrintfPointerFieldWidth = 2 + 2 * sizeof(void*);
-
-// Print a program counter, its stack frame size, and its symbol name.
-// Note that there is a separate symbolize_pc argument. Return addresses may be
-// at the end of the function, and this allows the caller to back up from pc if
-// appropriate.
-static void DumpPCAndFrameSizeAndSymbol(void (*writerfn)(const char*, void*),
-                                        void* writerfn_arg, void* pc,
-                                        void* symbolize_pc, int framesize,
-                                        const char* const prefix) {
-  char tmp[1024];
-  const char* symbol = "(unknown)";
-  if (absl::Symbolize(symbolize_pc, tmp, sizeof(tmp))) {
-    symbol = tmp;
-  }
-  char buf[1024];
-  if (framesize <= 0) {
-    snprintf(buf, sizeof(buf), "%s@ %*p  (unknown)  %s\n", prefix,
-             kPrintfPointerFieldWidth, pc, symbol);
-  } else {
-    snprintf(buf, sizeof(buf), "%s@ %*p  %9d  %s\n", prefix,
-             kPrintfPointerFieldWidth, pc, framesize, symbol);
-  }
-  writerfn(buf, writerfn_arg);
-}
-
-// Print a program counter and the corresponding stack frame size.
-static void DumpPCAndFrameSize(void (*writerfn)(const char*, void*),
-                               void* writerfn_arg, void* pc, int framesize,
-                               const char* const prefix) {
-  char buf[100];
-  if (framesize <= 0) {
-    snprintf(buf, sizeof(buf), "%s@ %*p  (unknown)\n", prefix,
-             kPrintfPointerFieldWidth, pc);
-  } else {
-    snprintf(buf, sizeof(buf), "%s@ %*p  %9d\n", prefix,
-             kPrintfPointerFieldWidth, pc, framesize);
-  }
-  writerfn(buf, writerfn_arg);
-}
-
-void DumpPCAndFrameSizesAndStackTrace(
-    void* pc, void* const stack[], int frame_sizes[], int depth,
-    int min_dropped_frames, bool symbolize_stacktrace,
-    void (*writerfn)(const char*, void*), void* writerfn_arg) {
+void DumpPCAndFrameSizesAndStackTrace(void* const pc, void* const stack[],
+                                      int frame_sizes[], int depth,
+                                      int min_dropped_frames,
+                                      bool symbolize_stacktrace,
+                                      OutputWriter* writer, void* writer_arg) {
   if (pc != nullptr) {
     // We don't know the stack frame size for PC, use 0.
     if (symbolize_stacktrace) {
-      DumpPCAndFrameSizeAndSymbol(writerfn, writerfn_arg, pc, pc, 0, "PC: ");
+      DumpPCAndFrameSizeAndSymbol(writer, writer_arg, pc, pc, 0, "PC: ");
     } else {
-      DumpPCAndFrameSize(writerfn, writerfn_arg, pc, 0, "PC: ");
+      DumpPCAndFrameSize(writer, writer_arg, pc, 0, "PC: ");
     }
   }
   for (int i = 0; i < depth; i++) {
@@ -182,20 +253,61 @@ void DumpPCAndFrameSizesAndStackTrace(
       // call to a function annotated noreturn (e.g. CHECK). Note that we don't
       // do this for pc above, as the adjustment is only correct for return
       // addresses.
-      DumpPCAndFrameSizeAndSymbol(writerfn, writerfn_arg, stack[i],
+      DumpPCAndFrameSizeAndSymbol(writer, writer_arg, stack[i],
                                   reinterpret_cast<char*>(stack[i]) - 1,
                                   frame_sizes[i], "    ");
     } else {
-      DumpPCAndFrameSize(writerfn, writerfn_arg, stack[i], frame_sizes[i],
-                         "    ");
+      DumpPCAndFrameSize(writer, writer_arg, stack[i], frame_sizes[i], "    ");
     }
   }
   if (min_dropped_frames > 0) {
     char buf[100];
     snprintf(buf, sizeof(buf), "    @ ... and at least %d more frames\n",
              min_dropped_frames);
-    writerfn(buf, writerfn_arg);
+    writer(buf, writer_arg);
+  }
+}
+
+// Dump current stack trace as directed by writer.
+// Make sure this function is not inlined to avoid skipping too many top frames.
+ABSL_ATTRIBUTE_NOINLINE
+void DumpStackTrace(int min_dropped_frames, int max_num_frames,
+                    bool symbolize_stacktrace, OutputWriter* writer,
+                    void* writer_arg) {
+  // Print stack trace
+  void* stack_buf[kDefaultDumpStackFramesLimit];
+  void** stack = stack_buf;
+  int num_stack = kDefaultDumpStackFramesLimit;
+  int allocated_bytes = 0;
+
+  if (num_stack >= max_num_frames) {
+    // User requested fewer frames than we already have space for.
+    num_stack = max_num_frames;
+  } else {
+    const size_t needed_bytes = max_num_frames * sizeof(stack[0]);
+    void* p = Allocate(needed_bytes);
+    if (p != nullptr) {  // We got the space.
+      num_stack = max_num_frames;
+      stack = reinterpret_cast<void**>(p);
+      allocated_bytes = needed_bytes;
+    }
   }
+
+  size_t depth = absl::GetStackTrace(stack, num_stack, min_dropped_frames + 1);
+  for (size_t i = 0; i < depth; i++) {
+    if (symbolize_stacktrace) {
+      DumpPCAndSymbol(writer, writer_arg, stack[i], "    ");
+    } else {
+      DumpPC(writer, writer_arg, stack[i], "    ");
+    }
+  }
+
+  auto hook = GetDebugStackTraceHook();
+  if (hook != nullptr) {
+    (*hook)(stack, depth, writer, writer_arg);
+  }
+
+  if (allocated_bytes != 0) Deallocate(stack, allocated_bytes);
 }
 
 }  // namespace debugging_internal
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/examine_stack.h b/contrib/restricted/abseil-cpp/absl/debugging/internal/examine_stack.h
index 393369131f1..190af87f1c3 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/examine_stack.h
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/examine_stack.h
@@ -23,17 +23,39 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
+// Type of function used for printing in stack trace dumping, etc.
+// We avoid closures to keep things simple.
+typedef void OutputWriter(const char*, void*);
+
+// RegisterDebugStackTraceHook() allows to register a single routine
+// `hook` that is called each time DumpStackTrace() is called.
+// `hook` may be called from a signal handler.
+typedef void (*SymbolizeUrlEmitter)(void* const stack[], int depth,
+                                    OutputWriter* writer, void* writer_arg);
+
+// Registration of SymbolizeUrlEmitter for use inside of a signal handler.
+// This is inherently unsafe and must be signal safe code.
+void RegisterDebugStackTraceHook(SymbolizeUrlEmitter hook);
+SymbolizeUrlEmitter GetDebugStackTraceHook();
+
 // Returns the program counter from signal context, or nullptr if
 // unknown. `vuc` is a ucontext_t*. We use void* to avoid the use of
 // ucontext_t on non-POSIX systems.
-void* GetProgramCounter(void* vuc);
+void* GetProgramCounter(void* const vuc);
 
-// Uses `writerfn` to dump the program counter, stack trace, and stack
+// Uses `writer` to dump the program counter, stack trace, and stack
 // frame sizes.
-void DumpPCAndFrameSizesAndStackTrace(
-    void* pc, void* const stack[], int frame_sizes[], int depth,
-    int min_dropped_frames, bool symbolize_stacktrace,
-    void (*writerfn)(const char*, void*), void* writerfn_arg);
+void DumpPCAndFrameSizesAndStackTrace(void* const pc, void* const stack[],
+                                      int frame_sizes[], int depth,
+                                      int min_dropped_frames,
+                                      bool symbolize_stacktrace,
+                                      OutputWriter* writer, void* writer_arg);
+
+// Dump current stack trace omitting the topmost `min_dropped_frames` stack
+// frames.
+void DumpStackTrace(int min_dropped_frames, int max_num_frames,
+                    bool symbolize_stacktrace, OutputWriter* writer,
+                    void* writer_arg);
 
 }  // namespace debugging_internal
 ABSL_NAMESPACE_END
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc
index f4859d7c210..4f9db9d66b6 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc
@@ -176,12 +176,17 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
     // Implementation detail: we clamp the max of frames we are willing to
     // count, so as not to spend too much time in the loop below.
     const int kMaxUnwind = 200;
-    int j = 0;
-    for (; frame_pointer != nullptr && j < kMaxUnwind; j++) {
+    int num_dropped_frames = 0;
+    for (int j = 0; frame_pointer != nullptr && j < kMaxUnwind; j++) {
+      if (skip_count > 0) {
+        skip_count--;
+      } else {
+        num_dropped_frames++;
+      }
       frame_pointer =
           NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
     }
-    *min_dropped_frames = j;
+    *min_dropped_frames = num_dropped_frames;
   }
   return n;
 }
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_arm-inl.inc b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_arm-inl.inc
index 2a1bf2e8869..102a2a1251a 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_arm-inl.inc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_arm-inl.inc
@@ -112,11 +112,16 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
     // Implementation detail: we clamp the max of frames we are willing to
     // count, so as not to spend too much time in the loop below.
     const int kMaxUnwind = 200;
-    int j = 0;
-    for (; sp != nullptr && j < kMaxUnwind; j++) {
+    int num_dropped_frames = 0;
+    for (int j = 0; sp != nullptr && j < kMaxUnwind; j++) {
+      if (skip_count > 0) {
+        skip_count--;
+      } else {
+        num_dropped_frames++;
+      }
       sp = NextStackFrame<!IS_STACK_FRAMES>(sp);
     }
-    *min_dropped_frames = j;
+    *min_dropped_frames = num_dropped_frames;
   }
   return n;
 }
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_config.h b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_config.h
index ff21b719a0c..3929b1b7349 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_config.h
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_config.h
@@ -37,7 +37,8 @@
   "absl/debugging/internal/stacktrace_generic-inl.inc"
 #endif  // defined(ABSL_HAVE_THREAD_LOCAL)
 
-#elif defined(__EMSCRIPTEN__)
+// Emscripten stacktraces rely on JS. Do not use them in standalone mode.
+#elif defined(__EMSCRIPTEN__) && !defined(STANDALONE_WASM)
 #define ABSL_STACKTRACE_INL_HEADER \
   "absl/debugging/internal/stacktrace_emscripten-inl.inc"
 
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_powerpc-inl.inc b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_powerpc-inl.inc
index cf8c05160c5..085cef67026 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_powerpc-inl.inc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_powerpc-inl.inc
@@ -231,11 +231,16 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
     // Implementation detail: we clamp the max of frames we are willing to
     // count, so as not to spend too much time in the loop below.
     const int kMaxUnwind = 1000;
-    int j = 0;
-    for (; next_sp != nullptr && j < kMaxUnwind; j++) {
+    int num_dropped_frames = 0;
+    for (int j = 0; next_sp != nullptr && j < kMaxUnwind; j++) {
+      if (skip_count > 0) {
+        skip_count--;
+      } else {
+        num_dropped_frames++;
+      }
       next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(next_sp, ucp);
     }
-    *min_dropped_frames = j;
+    *min_dropped_frames = num_dropped_frames;
   }
   return n;
 }
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_riscv-inl.inc b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_riscv-inl.inc
index 8cbc78548c6..7123b71bc38 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_riscv-inl.inc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_riscv-inl.inc
@@ -56,7 +56,7 @@ static const unsigned char *GetKernelRtSigreturnAddress() {
     absl::debugging_internal::VDSOSupport::SymbolInfo symbol_info;
     // Symbol versioning pulled from arch/riscv/kernel/vdso/vdso.lds at v5.10.
     auto lookup = [&](int type) {
-      return vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_4.15", type,
+      return vdso.LookupSymbol("__vdso_rt_sigreturn", "LINUX_4.15", type,
                                &symbol_info);
     };
     if ((!lookup(STT_FUNC) && !lookup(STT_NOTYPE)) ||
@@ -171,26 +171,21 @@ ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS  // May read random elements from stack.
 ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY   // May read random elements from stack.
 static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
                       const void *ucp, int *min_dropped_frames) {
+  // The `frame_pointer` that is computed here points to the top of the frame.
+  // The two words preceding the address are the return address and the previous
+  // frame pointer.
 #if defined(__GNUC__)
   void **frame_pointer = reinterpret_cast<void **>(__builtin_frame_address(0));
 #else
 #error reading stack pointer not yet supported on this platform
 #endif
 
-  skip_count++;  // Skip the frame for this function.
   int n = 0;
-
-  // The `frame_pointer` that is computed here points to the top of the frame.
-  // The two words preceding the address are the return address and the previous
-  // frame pointer.  To find a PC value associated with the current frame, we
-  // need to go down a level in the call chain.  So we remember the return
-  // address of the last frame seen.  This does not work for the first stack
-  // frame, which belongs to `UnwindImp()` but we skip the frame for
-  // `UnwindImp()` anyway.
-  void *prev_return_address = nullptr;
-
+  void *return_address = nullptr;
   while (frame_pointer && n < max_depth) {
-    // The absl::GetStackFrames routine si called when we are in some
+    return_address = frame_pointer[-1];
+
+    // The absl::GetStackFrames routine is called when we are in some
     // informational context (the failure signal handler for example).  Use the
     // non-strict unwinding rules to produce a stack trace that is as complete
     // as possible (even if it contains a few bogus entries in some rare cases).
@@ -200,26 +195,33 @@ static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
     if (skip_count > 0) {
       skip_count--;
     } else {
-      result[n] = prev_return_address;
+      result[n] = return_address;
       if (IS_STACK_FRAMES) {
         sizes[n] = ComputeStackFrameSize(frame_pointer, next_frame_pointer);
       }
       n++;
     }
-    prev_return_address = frame_pointer[-1];
+
     frame_pointer = next_frame_pointer;
   }
+
   if (min_dropped_frames != nullptr) {
     // Implementation detail: we clamp the max of frames we are willing to
     // count, so as not to spend too much time in the loop below.
     const int kMaxUnwind = 200;
-    int j = 0;
-    for (; frame_pointer != nullptr && j < kMaxUnwind; j++) {
+    int num_dropped_frames = 0;
+    for (int j = 0; frame_pointer != nullptr && j < kMaxUnwind; j++) {
+      if (skip_count > 0) {
+        skip_count--;
+      } else {
+        num_dropped_frames++;
+      }
       frame_pointer =
           NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
     }
-    *min_dropped_frames = j;
+    *min_dropped_frames = num_dropped_frames;
   }
+
   return n;
 }
 
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_x86-inl.inc b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_x86-inl.inc
index 847a5473590..1b5d8235a82 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_x86-inl.inc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/stacktrace_x86-inl.inc
@@ -341,12 +341,17 @@ static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
     // Implementation detail: we clamp the max of frames we are willing to
     // count, so as not to spend too much time in the loop below.
     const int kMaxUnwind = 1000;
-    int j = 0;
-    for (; fp != nullptr && j < kMaxUnwind; j++) {
+    int num_dropped_frames = 0;
+    for (int j = 0; fp != nullptr && j < kMaxUnwind; j++) {
+      if (skip_count > 0) {
+        skip_count--;
+      } else {
+        num_dropped_frames++;
+      }
       fp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(fp, ucp, stack_low,
                                                              stack_high);
     }
-    *min_dropped_frames = j;
+    *min_dropped_frames = num_dropped_frames;
   }
   return n;
 }
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/internal/vdso_support.cc b/contrib/restricted/abseil-cpp/absl/debugging/internal/vdso_support.cc
index 977a9f6b3c5..40eb055f691 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/internal/vdso_support.cc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/internal/vdso_support.cc
@@ -33,7 +33,7 @@
 #endif
 #include <unistd.h>
 
-#if defined(__GLIBC__) && \
+#if !defined(__UCLIBC__) && defined(__GLIBC__) && \
     (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 16))
 #define ABSL_HAVE_GETAUXVAL
 #endif
@@ -50,8 +50,14 @@
 #define AT_SYSINFO_EHDR 33  // for crosstoolv10
 #endif
 
+#if defined(__NetBSD__)
+using Elf32_auxv_t = Aux32Info;
+using Elf64_auxv_t = Aux64Info;
+#endif
 #if defined(__FreeBSD__)
+#if defined(__ELF_WORD_SIZE) && __ELF_WORD_SIZE == 64
 using Elf64_auxv_t = Elf64_Auxinfo;
+#endif
 using Elf32_auxv_t = Elf32_Auxinfo;
 #endif
 
@@ -63,7 +69,9 @@ ABSL_CONST_INIT
 std::atomic<const void *> VDSOSupport::vdso_base_(
     debugging_internal::ElfMemImage::kInvalidBase);
 
-std::atomic<VDSOSupport::GetCpuFn> VDSOSupport::getcpu_fn_(&InitAndGetCPU);
+ABSL_CONST_INIT std::atomic<VDSOSupport::GetCpuFn> VDSOSupport::getcpu_fn_(
+    &InitAndGetCPU);
+
 VDSOSupport::VDSOSupport()
     // If vdso_base_ is still set to kInvalidBase, we got here
     // before VDSOSupport::Init has been called. Call it now.
@@ -104,8 +112,13 @@ const void *VDSOSupport::Init() {
     ElfW(auxv_t) aux;
     while (read(fd, &aux, sizeof(aux)) == sizeof(aux)) {
       if (aux.a_type == AT_SYSINFO_EHDR) {
+#if defined(__NetBSD__)
+        vdso_base_.store(reinterpret_cast<void *>(aux.a_v),
+                         std::memory_order_relaxed);
+#else
         vdso_base_.store(reinterpret_cast<void *>(aux.a_un.a_val),
                          std::memory_order_relaxed);
+#endif
         break;
       }
     }
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/leak_check.cc b/contrib/restricted/abseil-cpp/absl/debugging/leak_check.cc
index 764ca0ad008..195e82bf16e 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/leak_check.cc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/leak_check.cc
@@ -11,29 +11,19 @@
 // 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.
-
+//
 // Wrappers around lsan_interface functions.
-// When lsan is not linked in, these functions are not available,
-// therefore Abseil code which depends on these functions is conditioned on the
-// definition of LEAK_SANITIZER.
-#include "absl/base/attributes.h"
-#include "absl/debugging/leak_check.h"
+//
+// These are always-available run-time functions manipulating the LeakSanitizer,
+// even when the lsan_interface (and LeakSanitizer) is not available. When
+// LeakSanitizer is not linked in, these functions become no-op stubs.
 
-#ifndef LEAK_SANITIZER
+#include "absl/debugging/leak_check.h"
 
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-bool HaveLeakSanitizer() { return false; }
-bool LeakCheckerIsActive() { return false; }
-void DoIgnoreLeak(const void*) { }
-void RegisterLivePointers(const void*, size_t) { }
-void UnRegisterLivePointers(const void*, size_t) { }
-LeakCheckDisabler::LeakCheckDisabler() { }
-LeakCheckDisabler::~LeakCheckDisabler() { }
-ABSL_NAMESPACE_END
-}  // namespace absl
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
 
-#else
+#if defined(ABSL_HAVE_LEAK_SANITIZER)
 
 #include <sanitizer/lsan_interface.h>
 
@@ -66,4 +56,18 @@ LeakCheckDisabler::~LeakCheckDisabler() { __lsan_enable(); }
 ABSL_NAMESPACE_END
 }  // namespace absl
 
-#endif  // LEAK_SANITIZER
+#else  // defined(ABSL_HAVE_LEAK_SANITIZER)
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+bool HaveLeakSanitizer() { return false; }
+bool LeakCheckerIsActive() { return false; }
+void DoIgnoreLeak(const void*) { }
+void RegisterLivePointers(const void*, size_t) { }
+void UnRegisterLivePointers(const void*, size_t) { }
+LeakCheckDisabler::LeakCheckDisabler() { }
+LeakCheckDisabler::~LeakCheckDisabler() { }
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // defined(ABSL_HAVE_LEAK_SANITIZER)
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/leak_check.h b/contrib/restricted/abseil-cpp/absl/debugging/leak_check.h
index 5fc2b052e41..eff162f67f4 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/leak_check.h
+++ b/contrib/restricted/abseil-cpp/absl/debugging/leak_check.h
@@ -24,7 +24,24 @@
 // Note: this leak checking API is not yet supported in MSVC.
 // Leak checking is enabled by default in all ASan builds.
 //
-// See https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer
+// https://clang.llvm.org/docs/LeakSanitizer.html
+// https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer
+//
+// GCC and Clang both automatically enable LeakSanitizer when AddressSanitizer
+// is enabled. To use the mode, simply pass `-fsanitize=address` to both the
+// compiler and linker. An example Bazel command could be
+//
+//   $ bazel test --copt=-fsanitize=address --linkopt=-fsanitize=address ...
+//
+// GCC and Clang auto support a standalone LeakSanitizer mode (a mode which does
+// not also use AddressSanitizer). To use the mode, simply pass
+// `-fsanitize=leak` to both the compiler and linker. Since GCC does not
+// currently provide a way of detecting this mode at compile-time, GCC users
+// must also pass -DLEAK_SANIITIZER to the compiler. An example Bazel command
+// could be
+//
+//   $ bazel test --copt=-DLEAK_SANITIZER --copt=-fsanitize=leak
+//     --linkopt=-fsanitize=leak ...
 //
 // -----------------------------------------------------------------------------
 #ifndef ABSL_DEBUGGING_LEAK_CHECK_H_
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/leak_check_disable.cc b/contrib/restricted/abseil-cpp/absl/debugging/leak_check_disable.cc
deleted file mode 100644
index 924d6e3d543..00000000000
--- a/contrib/restricted/abseil-cpp/absl/debugging/leak_check_disable.cc
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// 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
-//
-//      https://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.
-
-// Disable LeakSanitizer when this file is linked in.
-// This function overrides __lsan_is_turned_off from sanitizer/lsan_interface.h
-extern "C" int __lsan_is_turned_off();
-extern "C" int __lsan_is_turned_off() {
-  return 1;
-}
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/symbolize.cc b/contrib/restricted/abseil-cpp/absl/debugging/symbolize.cc
index f1abdfda592..638d3954aec 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/symbolize.cc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/symbolize.cc
@@ -23,6 +23,11 @@
 #endif
 #endif
 
+// Emscripten symbolization relies on JS. Do not use them in standalone mode.
+#if defined(__EMSCRIPTEN__) && !defined(STANDALONE_WASM)
+#define ABSL_INTERNAL_HAVE_SYMBOLIZE_WASM
+#endif
+
 #if defined(ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE)
 #include "absl/debugging/symbolize_elf.inc"
 #elif defined(ABSL_INTERNAL_HAVE_SYMBOLIZE_WIN32)
@@ -31,7 +36,7 @@
 #include "absl/debugging/symbolize_win32.inc"
 #elif defined(__APPLE__)
 #include "absl/debugging/symbolize_darwin.inc"
-#elif defined(__EMSCRIPTEN__)
+#elif defined(ABSL_INTERNAL_HAVE_SYMBOLIZE_WASM)
 #include "absl/debugging/symbolize_emscripten.inc"
 #else
 #include "absl/debugging/symbolize_unimplemented.inc"
diff --git a/contrib/restricted/abseil-cpp/absl/debugging/symbolize_elf.inc b/contrib/restricted/abseil-cpp/absl/debugging/symbolize_elf.inc
index 3ff343d64f6..9bfdd9151a2 100644
--- a/contrib/restricted/abseil-cpp/absl/debugging/symbolize_elf.inc
+++ b/contrib/restricted/abseil-cpp/absl/debugging/symbolize_elf.inc
@@ -323,6 +323,7 @@ class Symbolizer {
                                            const ptrdiff_t relocation,
                                            char *out, int out_size,
                                            char *tmp_buf, int tmp_buf_size);
+  const char *GetUncachedSymbol(const void *pc);
 
   enum {
     SYMBOL_BUF_SIZE = 3072,
@@ -1145,6 +1146,14 @@ bool Symbolizer::RegisterObjFile(const char *filename,
                      reinterpret_cast<uintptr_t>(old->end_addr), old->filename);
       }
       return true;
+    } else if (old->end_addr == start_addr &&
+               reinterpret_cast<uintptr_t>(old->start_addr) - old->offset ==
+                   reinterpret_cast<uintptr_t>(start_addr) - offset &&
+               strcmp(old->filename, filename) == 0) {
+      // Two contiguous map entries that span a contiguous region of the file,
+      // perhaps because some part of the file was mlock()ed. Combine them.
+      old->end_addr = end_addr;
+      return true;
     }
   }
   ObjFile *obj = impl->addr_map_.Add();
@@ -1333,13 +1342,7 @@ static bool MaybeInitializeObjFile(ObjFile *obj) {
 // they are called here as well.
 // To keep stack consumption low, we would like this function to not
 // get inlined.
-const char *Symbolizer::GetSymbol(const void *const pc) {
-  const char *entry = FindSymbolInCache(pc);
-  if (entry != nullptr) {
-    return entry;
-  }
-  symbol_buf_[0] = '\0';
-
+const char *Symbolizer::GetUncachedSymbol(const void *pc) {
   ObjFile *const obj = FindObjFile(pc, 1);
   ptrdiff_t relocation = 0;
   int fd = -1;
@@ -1427,6 +1430,42 @@ const char *Symbolizer::GetSymbol(const void *const pc) {
   return InsertSymbolInCache(pc, symbol_buf_);
 }
 
+const char *Symbolizer::GetSymbol(const void *pc) {
+  const char *entry = FindSymbolInCache(pc);
+  if (entry != nullptr) {
+    return entry;
+  }
+  symbol_buf_[0] = '\0';
+
+#ifdef __hppa__
+  {
+    // In some contexts (e.g., return addresses), PA-RISC uses the lowest two
+    // bits of the address to indicate the privilege level. Clear those bits
+    // before trying to symbolize.
+    const auto pc_bits = reinterpret_cast<uintptr_t>(pc);
+    const auto address = pc_bits & ~0x3;
+    entry = GetUncachedSymbol(reinterpret_cast<const void *>(address));
+    if (entry != nullptr) {
+      return entry;
+    }
+
+    // In some contexts, PA-RISC also uses bit 1 of the address to indicate that
+    // this is a cross-DSO function pointer. Such function pointers actually
+    // point to a procedure label, a struct whose first 32-bit (pointer) element
+    // actually points to the function text. With no symbol found for this
+    // address so far, try interpreting it as a cross-DSO function pointer and
+    // see how that goes.
+    if (pc_bits & 0x2) {
+      return GetUncachedSymbol(*reinterpret_cast<const void *const *>(address));
+    }
+
+    return nullptr;
+  }
+#else
+  return GetUncachedSymbol(pc);
+#endif
+}
+
 bool RemoveAllSymbolDecorators(void) {
   if (!g_decorators_mu.TryLock()) {
     // Someone else is using decorators. Get out.