Update contrib/restricted/abseil-cpp-tstring to 20230802.0

11 files changed, 148 insertions, 65 deletions

diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/failure_signal_handler.cc b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/failure_signal_handler.cc
index 25ed376e0f3..ab8b62dda2d 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/failure_signal_handler.cc
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/failure_signal_handler.cc
@@ -31,6 +31,13 @@
 
 #ifdef Y_ABSL_HAVE_MMAP
 #include <sys/mman.h>
+#if defined(MAP_ANON) && !defined(MAP_ANONYMOUS)
+#define MAP_ANONYMOUS MAP_ANON
+#endif
+#endif
+
+#ifdef __linux__
+#include <sys/prctl.h>
 #endif
 
 #include <algorithm>
@@ -77,10 +84,10 @@ struct FailureSignalData {
   struct sigaction previous_action;
   // StructSigaction is used to silence -Wmissing-field-initializers.
   using StructSigaction = struct sigaction;
-  #define FSD_PREVIOUS_INIT FailureSignalData::StructSigaction()
+#define FSD_PREVIOUS_INIT FailureSignalData::StructSigaction()
 #else
   void (*previous_handler)(int);
-  #define FSD_PREVIOUS_INIT SIG_DFL
+#define FSD_PREVIOUS_INIT SIG_DFL
 #endif
 };
 
@@ -132,7 +139,7 @@ const char* FailureSignalToString(int signo) {
 #ifdef Y_ABSL_HAVE_SIGALTSTACK
 
 static bool SetupAlternateStackOnce() {
-#if defined(__wasm__) || defined (__asjms__)
+#if defined(__wasm__) || defined(__asjms__)
   const size_t page_mask = getpagesize() - 1;
 #else
   const size_t page_mask = static_cast<size_t>(sysconf(_SC_PAGESIZE)) - 1;
@@ -154,9 +161,6 @@ static bool SetupAlternateStackOnce() {
 #ifndef MAP_STACK
 #define MAP_STACK 0
 #endif
-#if defined(MAP_ANON) && !defined(MAP_ANONYMOUS)
-#define MAP_ANONYMOUS MAP_ANON
-#endif
   sigstk.ss_sp = mmap(nullptr, sigstk.ss_size, PROT_READ | PROT_WRITE,
                       MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
   if (sigstk.ss_sp == MAP_FAILED) {
@@ -172,6 +176,20 @@ static bool SetupAlternateStackOnce() {
   if (sigaltstack(&sigstk, nullptr) != 0) {
     Y_ABSL_RAW_LOG(FATAL, "sigaltstack() failed with errno=%d", errno);
   }
+
+#ifdef __linux__
+#if defined(PR_SET_VMA) && defined(PR_SET_VMA_ANON_NAME)
+  // Make a best-effort attempt to name the allocated region in
+  // /proc/$PID/smaps.
+  //
+  // The call to prctl() may fail if the kernel was not configured with the
+  // CONFIG_ANON_VMA_NAME kernel option.  This is OK since the call is
+  // primarily a debugging aid.
+  prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, sigstk.ss_sp, sigstk.ss_size,
+        "y_absl-signalstack");
+#endif
+#endif  // __linux__
+
   return true;
 }
 
@@ -218,10 +236,6 @@ static void InstallOneFailureHandler(FailureSignalData* data,
 
 #endif
 
-static void WriteToStderr(const char* data) {
-  y_absl::raw_log_internal::AsyncSignalSafeWriteToStderr(data, strlen(data));
-}
-
 static void WriteSignalMessage(int signo, int cpu,
                                void (*writerfn)(const char*)) {
   char buf[96];
@@ -234,7 +248,7 @@ static void WriteSignalMessage(int signo, int cpu,
   if (signal_string != nullptr && signal_string[0] != '\0') {
     snprintf(buf, sizeof(buf), "*** %s received at time=%ld%s ***\n",
              signal_string,
-             static_cast<long>(time(nullptr)),   // NOLINT(runtime/int)
+             static_cast<long>(time(nullptr)),  // NOLINT(runtime/int)
              on_cpu);
   } else {
     snprintf(buf, sizeof(buf), "*** Signal %d received at time=%ld%s ***\n",
@@ -297,7 +311,8 @@ static void PortableSleepForSeconds(int seconds) {
   struct timespec sleep_time;
   sleep_time.tv_sec = seconds;
   sleep_time.tv_nsec = 0;
-  while (nanosleep(&sleep_time, &sleep_time) != 0 && errno == EINTR) {}
+  while (nanosleep(&sleep_time, &sleep_time) != 0 && errno == EINTR) {
+  }
 #endif
 }
 
@@ -307,9 +322,7 @@ static void PortableSleepForSeconds(int seconds) {
 // set amount of time. If AbslFailureSignalHandler() hangs for more than
 // the alarm timeout, ImmediateAbortSignalHandler() will abort the
 // program.
-static void ImmediateAbortSignalHandler(int) {
-  RaiseToDefaultHandler(SIGABRT);
-}
+static void ImmediateAbortSignalHandler(int) { RaiseToDefaultHandler(SIGABRT); }
 #endif
 
 // y_absl::base_internal::GetTID() returns pid_t on most platforms, but
@@ -362,7 +375,10 @@ static void AbslFailureSignalHandler(int signo, siginfo_t*, void* ucontext) {
 #endif
 
   // First write to stderr.
-  WriteFailureInfo(signo, ucontext, my_cpu, WriteToStderr);
+  WriteFailureInfo(
+      signo, ucontext, my_cpu, +[](const char* data) {
+        y_absl::raw_log_internal::AsyncSignalSafeWriteError(data, strlen(data));
+      });
 
   // Riskier code (because it is less likely to be async-signal-safe)
   // goes after this point.
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/failure_signal_handler.h b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/failure_signal_handler.h
index b4262642761..03ce76be424 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/failure_signal_handler.h
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/failure_signal_handler.h
@@ -62,7 +62,7 @@ struct FailureSignalHandlerOptions {
   // If true, try to run signal handlers on an alternate stack (if supported on
   // the given platform). An alternate stack is useful for program crashes due
   // to a stack overflow; by running on a alternate stack, the signal handler
-  // may run even when normal stack space has been exausted. The downside of
+  // may run even when normal stack space has been exhausted. The downside of
   // using an alternate stack is that extra memory for the alternate stack needs
   // to be pre-allocated.
   bool use_alternate_stack = true;
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/elf_mem_image.h b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/elf_mem_image.h
index a7dde972061..9c5e588fbbc 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/elf_mem_image.h
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/elf_mem_image.h
@@ -33,7 +33,8 @@
 
 #if defined(__ELF__) && !defined(__OpenBSD__) && !defined(__QNX__) && \
     !defined(__native_client__) && !defined(__asmjs__) &&             \
-    !defined(__wasm__) && !defined(__HAIKU__)
+    !defined(__wasm__) && !defined(__HAIKU__) && !defined(__sun) &&   \
+    !defined(__VXWORKS__) && !defined(__hexagon__)
 #define Y_ABSL_HAVE_ELF_MEM_IMAGE 1
 #endif
 
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/examine_stack.cc b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/examine_stack.cc
index 62d600f5a8a..284610b5d7b 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/examine_stack.cc
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/examine_stack.cc
@@ -24,6 +24,9 @@
 
 #ifdef Y_ABSL_HAVE_MMAP
 #include <sys/mman.h>
+#if defined(MAP_ANON) && !defined(MAP_ANONYMOUS)
+#define MAP_ANONYMOUS MAP_ANON
+#endif
 #endif
 
 #if defined(__linux__) || defined(__APPLE__)
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_aarch64-inl.inc b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_aarch64-inl.inc
index b9a79192225..04531613f8a 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_aarch64-inl.inc
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_aarch64-inl.inc
@@ -13,6 +13,7 @@
 #include <cassert>
 #include <cstdint>
 #include <iostream>
+#include <limits>
 
 #include "y_absl/base/attributes.h"
 #include "y_absl/debugging/internal/address_is_readable.h"
@@ -20,6 +21,10 @@
 #include "y_absl/debugging/stacktrace.h"
 
 static const size_t kUnknownFrameSize = 0;
+// Stack end to use when we don't know the actual stack end
+// (effectively just the end of address space).
+constexpr uintptr_t kUnknownStackEnd =
+    std::numeric_limits<size_t>::max() - sizeof(void *);
 
 #if defined(__linux__)
 // Returns the address of the VDSO __kernel_rt_sigreturn function, if present.
@@ -79,8 +84,9 @@ static inline size_t ComputeStackFrameSize(const T* low,
 // "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
 template<bool STRICT_UNWINDING, bool WITH_CONTEXT>
 Y_ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS  // May read random elements from stack.
-Y_ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY   // May read random elements from stack.
-static void **NextStackFrame(void **old_frame_pointer, const void *uc) {
+Y_ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY  // May read random elements from stack.
+static void **NextStackFrame(void **old_frame_pointer, const void *uc,
+                             size_t stack_low, size_t stack_high) {
   void **new_frame_pointer = reinterpret_cast<void**>(*old_frame_pointer);
   bool check_frame_size = true;
 
@@ -94,16 +100,21 @@ static void **NextStackFrame(void **old_frame_pointer, const void *uc) {
       void **const pre_signal_frame_pointer =
           reinterpret_cast<void **>(ucv->uc_mcontext.regs[29]);
 
+      // The most recent signal always needs special handling to find the frame
+      // pointer, but a nested signal does not.  If pre_signal_frame_pointer is
+      // earlier in the stack than the old_frame_pointer, then use it. If it is
+      // later, then we have already unwound through it and it needs no special
+      // handling.
+      if (pre_signal_frame_pointer >= old_frame_pointer) {
+        new_frame_pointer = pre_signal_frame_pointer;
+      }
       // Check that alleged frame pointer is actually readable. This is to
       // prevent "double fault" in case we hit the first fault due to e.g.
       // stack corruption.
       if (!y_absl::debugging_internal::AddressIsReadable(
-              pre_signal_frame_pointer))
+              new_frame_pointer))
         return nullptr;
 
-      // Alleged frame pointer is readable, use it for further unwinding.
-      new_frame_pointer = pre_signal_frame_pointer;
-
       // Skip frame size check if we return from a signal. We may be using a
       // an alternate stack for signals.
       check_frame_size = false;
@@ -121,8 +132,26 @@ static void **NextStackFrame(void **old_frame_pointer, const void *uc) {
     const size_t max_size = STRICT_UNWINDING ? 100000 : 1000000;
     const size_t frame_size =
         ComputeStackFrameSize(old_frame_pointer, new_frame_pointer);
-    if (frame_size == kUnknownFrameSize || frame_size > max_size)
-      return nullptr;
+    if (frame_size == kUnknownFrameSize)
+       return nullptr;
+    // A very large frame may mean corrupt memory or an erroneous frame
+    // pointer. But also maybe just a plain-old large frame.  Assume that if the
+    // frame is within the known stack, then it is valid.
+    if (frame_size > max_size) {
+       if (stack_high < kUnknownStackEnd &&
+          static_cast<size_t>(getpagesize()) < stack_low) {
+        const uintptr_t new_fp_u =
+            reinterpret_cast<uintptr_t>(new_frame_pointer);
+        // Stack bounds are known.
+        if (!(stack_low < new_fp_u && new_fp_u <= stack_high)) {
+          // new_frame_pointer is not within the known stack.
+          return nullptr;
+        }
+      } else {
+        // Stack bounds are unknown, prefer truncated stack to possible crash.
+        return nullptr;
+      }
+    }
   }
 
   return new_frame_pointer;
@@ -138,42 +167,49 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
 #else
 # error reading stack point not yet supported on this platform.
 #endif
-
   skip_count++;    // Skip the frame for this function.
   int n = 0;
 
+  // Assume that the first page is not stack.
+  size_t stack_low = static_cast<size_t>(getpagesize());
+  size_t stack_high = kUnknownStackEnd;
+
   // The frame pointer points to low address of a frame.  The first 64-bit
   // word of a frame points to the next frame up the call chain, which normally
   // is just after the high address of the current frame.  The second word of
-  // a frame contains return adress of to the caller.   To find a pc value
+  // a frame contains return address of to the caller.   To find a pc value
   // associated with the current frame, we need to go down a level in the call
   // chain.  So we remember return the 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;
+  // The nth frame size is the difference between the nth frame pointer and the
+  // the frame pointer below it in the call chain. There is no frame below the
+  // leaf frame, but this function is the leaf anyway, and we skip it.
+  void** prev_frame_pointer = nullptr;
 
-  while (frame_pointer && n < max_depth) {
-    // The y_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).
-    void **next_frame_pointer =
-        NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
-
+   while (frame_pointer && n < max_depth) {
     if (skip_count > 0) {
       skip_count--;
     } else {
       result[n] = prev_return_address;
       if (IS_STACK_FRAMES) {
         sizes[n] = static_cast<int>(
-            ComputeStackFrameSize(frame_pointer, next_frame_pointer));
+            ComputeStackFrameSize(prev_frame_pointer, frame_pointer));
       }
       n++;
     }
     prev_return_address = frame_pointer[1];
-    frame_pointer = next_frame_pointer;
+    prev_frame_pointer = frame_pointer;
+    // The y_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).
+    frame_pointer = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(
+        frame_pointer, ucp, stack_low, stack_high);
   }
+
   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.
@@ -185,8 +221,8 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
       } else {
         num_dropped_frames++;
       }
-      frame_pointer =
-          NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
+      frame_pointer = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(
+          frame_pointer, ucp, stack_low, stack_high);
     }
     *min_dropped_frames = num_dropped_frames;
   }
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_powerpc-inl.inc b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_powerpc-inl.inc
index 56dcd40c670..9edbe28c843 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_powerpc-inl.inc
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_powerpc-inl.inc
@@ -57,7 +57,7 @@ static inline void *StacktracePowerPCGetLR(void **sp) {
   // This check is in case the compiler doesn't define _CALL_SYSV.
   return *(sp+1);
 #else
-#error Need to specify the PPC ABI for your archiecture.
+#error Need to specify the PPC ABI for your architecture.
 #endif
 }
 
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_x86-inl.inc b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_x86-inl.inc
index 278a0b6da48..3ee3502b192 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_x86-inl.inc
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/stacktrace_x86-inl.inc
@@ -40,7 +40,7 @@ using y_absl::debugging_internal::AddressIsReadable;
 
 #if defined(__linux__) && defined(__i386__)
 // Count "push %reg" instructions in VDSO __kernel_vsyscall(),
-// preceeding "syscall" or "sysenter".
+// preceding "syscall" or "sysenter".
 // If __kernel_vsyscall uses frame pointer, answer 0.
 //
 // kMaxBytes tells how many instruction bytes of __kernel_vsyscall
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/symbolize.h b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/symbolize.h
index c404b3cf91a..90a78d53174 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/symbolize.h
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/internal/symbolize.h
@@ -115,7 +115,7 @@ bool RemoveSymbolDecorator(int ticket);
 
 // Remove all installed decorators.  Returns true if successful, false if
 // symbolization is currently in progress.
-bool RemoveAllSymbolDecorators(void);
+bool RemoveAllSymbolDecorators();
 
 // Registers an address range to a file mapping.
 //
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/leak_check.cc b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/leak_check.cc
index 1cddc78cc8a..323d50604cc 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/leak_check.cc
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/leak_check.cc
@@ -65,8 +65,8 @@ bool LeakCheckerIsActive() { return false; }
 void DoIgnoreLeak(const void*) { }
 void RegisterLivePointers(const void*, size_t) { }
 void UnRegisterLivePointers(const void*, size_t) { }
-LeakCheckDisabler::LeakCheckDisabler() { }
-LeakCheckDisabler::~LeakCheckDisabler() { }
+LeakCheckDisabler::LeakCheckDisabler() = default;
+LeakCheckDisabler::~LeakCheckDisabler() = default;
 Y_ABSL_NAMESPACE_END
 }  // namespace y_absl
 
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/symbolize_elf.inc b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/symbolize_elf.inc
index 33ad4a9b0c1..81e31e01c8e 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/symbolize_elf.inc
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/symbolize_elf.inc
@@ -532,6 +532,11 @@ bool ForEachSection(int fd,
     return false;
   }
 
+  // Technically it can be larger, but in practice this never happens.
+  if (elf_header.e_shentsize != sizeof(ElfW(Shdr))) {
+    return false;
+  }
+
   ElfW(Shdr) shstrtab;
   off_t shstrtab_offset = static_cast<off_t>(elf_header.e_shoff) +
                           elf_header.e_shentsize * elf_header.e_shstrndx;
@@ -584,6 +589,11 @@ bool GetSectionHeaderByName(int fd, const char *name, size_t name_len,
     return false;
   }
 
+  // Technically it can be larger, but in practice this never happens.
+  if (elf_header.e_shentsize != sizeof(ElfW(Shdr))) {
+    return false;
+  }
+
   ElfW(Shdr) shstrtab;
   off_t shstrtab_offset = static_cast<off_t>(elf_header.e_shoff) +
                           elf_header.e_shentsize * elf_header.e_shstrndx;
@@ -648,8 +658,10 @@ static bool ShouldPickFirstSymbol(const ElfW(Sym) & symbol1,
 }
 
 // Return true if an address is inside a section.
-static bool InSection(const void *address, const ElfW(Shdr) * section) {
-  const char *start = reinterpret_cast<const char *>(section->sh_addr);
+static bool InSection(const void *address, ptrdiff_t relocation,
+                      const ElfW(Shdr) * section) {
+  const char *start = reinterpret_cast<const char *>(
+      section->sh_addr + static_cast<ElfW(Addr)>(relocation));
   size_t size = static_cast<size_t>(section->sh_size);
   return start <= address && address < (start + size);
 }
@@ -689,8 +701,8 @@ static Y_ABSL_ATTRIBUTE_NOINLINE FindSymbolResult FindSymbol(
   // starting address.  However, we do not always want to use the real
   // starting address because we sometimes want to symbolize a function
   // pointer into the .opd section, e.g. FindSymbol(&foo,...).
-  const bool pc_in_opd =
-      kPlatformUsesOPDSections && opd != nullptr && InSection(pc, opd);
+  const bool pc_in_opd = kPlatformUsesOPDSections && opd != nullptr &&
+                         InSection(pc, relocation, opd);
   const bool deref_function_descriptor_pointer =
       kPlatformUsesOPDSections && opd != nullptr && !pc_in_opd;
 
@@ -730,7 +742,7 @@ static Y_ABSL_ATTRIBUTE_NOINLINE FindSymbolResult FindSymbol(
 #endif
 
       if (deref_function_descriptor_pointer &&
-          InSection(original_start_address, opd)) {
+          InSection(original_start_address, /*relocation=*/0, opd)) {
         // The opd section is mapped into memory.  Just dereference
         // start_address to get the first double word, which points to the
         // function entry.
@@ -1326,7 +1338,7 @@ static bool MaybeInitializeObjFile(ObjFile *obj) {
     const int phnum = obj->elf_header.e_phnum;
     const int phentsize = obj->elf_header.e_phentsize;
     auto phoff = static_cast<off_t>(obj->elf_header.e_phoff);
-    size_t num_executable_load_segments = 0;
+    size_t num_interesting_load_segments = 0;
     for (int j = 0; j < phnum; j++) {
       ElfW(Phdr) phdr;
       if (!ReadFromOffsetExact(obj->fd, &phdr, sizeof(phdr), phoff)) {
@@ -1335,23 +1347,35 @@ static bool MaybeInitializeObjFile(ObjFile *obj) {
         return false;
       }
       phoff += phentsize;
-      constexpr int rx = PF_X | PF_R;
-      if (phdr.p_type != PT_LOAD || (phdr.p_flags & rx) != rx) {
-        // Not a LOAD segment, or not executable code.
+
+#if defined(__powerpc__) && !(_CALL_ELF > 1)
+      // On the PowerPC ELF v1 ABI, function pointers actually point to function
+      // descriptors. These descriptors are stored in an .opd section, which is
+      // mapped read-only. We thus need to look at all readable segments, not
+      // just the executable ones.
+      constexpr int interesting = PF_R;
+#else
+      constexpr int interesting = PF_X | PF_R;
+#endif
+
+      if (phdr.p_type != PT_LOAD
+          || (phdr.p_flags & interesting) != interesting) {
+        // Not a LOAD segment, not executable code, and not a function
+        // descriptor.
         continue;
       }
-      if (num_executable_load_segments < obj->phdr.size()) {
-        memcpy(&obj->phdr[num_executable_load_segments++], &phdr, sizeof(phdr));
+      if (num_interesting_load_segments < obj->phdr.size()) {
+        memcpy(&obj->phdr[num_interesting_load_segments++], &phdr, sizeof(phdr));
       } else {
         Y_ABSL_RAW_LOG(
-            WARNING, "%s: too many executable LOAD segments: %zu >= %zu",
-            obj->filename, num_executable_load_segments, obj->phdr.size());
+            WARNING, "%s: too many interesting LOAD segments: %zu >= %zu",
+            obj->filename, num_interesting_load_segments, obj->phdr.size());
         break;
       }
     }
-    if (num_executable_load_segments == 0) {
-      // This object has no "r-x" LOAD segments. That's unexpected.
-      Y_ABSL_RAW_LOG(WARNING, "%s: no executable LOAD segments", obj->filename);
+    if (num_interesting_load_segments == 0) {
+      // This object has no interesting LOAD segments. That's unexpected.
+      Y_ABSL_RAW_LOG(WARNING, "%s: no interesting LOAD segments", obj->filename);
       return false;
     }
   }
@@ -1379,8 +1403,8 @@ const char *Symbolizer::GetUncachedSymbol(const void *pc) {
         // X in the file will have a start address of [true relocation]+X.
         relocation = static_cast<ptrdiff_t>(start_addr - obj->offset);
 
-        // Note: some binaries have multiple "rx" LOAD segments. We must
-        // find the right one.
+        // Note: some binaries have multiple LOAD segments that can contain
+        // function pointers. We must find the right one.
         ElfW(Phdr) *phdr = nullptr;
         for (size_t j = 0; j < obj->phdr.size(); j++) {
           ElfW(Phdr) &p = obj->phdr[j];
@@ -1390,7 +1414,7 @@ const char *Symbolizer::GetUncachedSymbol(const void *pc) {
             Y_ABSL_RAW_CHECK(p.p_type == PT_NULL, "unexpected p_type");
             break;
           }
-          if (pc < reinterpret_cast<void *>(start_addr + p.p_memsz)) {
+          if (pc < reinterpret_cast<void *>(start_addr + p.p_vaddr + p.p_memsz)) {
             phdr = &p;
             break;
           }
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/symbolize_emscripten.inc b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/symbolize_emscripten.inc
index 5aa97cca46e..558160f9705 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/symbolize_emscripten.inc
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/debugging/symbolize_emscripten.inc
@@ -50,6 +50,9 @@ bool Symbolize(const void* pc, char* out, int out_size) {
   if (!HaveOffsetConverter()) {
     return false;
   }
+  if (pc == nullptr || out_size <= 0) {
+    return false;
+  }
   const char* func_name = emscripten_pc_get_function(pc);
   if (func_name == nullptr) {
     return false;