Enable stack trace symbolization for OSS builds (#9687)

Summary:
Historically, HHVM statically linked the system libbfd to power stack trace symbolization in its crash reports and in perf map files. This was disabled for OSS in D2137703[1] because of the wildly differing libbfd ABI across target systems. D3742004[2] and D3855027[3] then brought in folly::Symbolizer for both use cases, but this remained gated behind a Meta-only define.

folly::Symbolizer has been stable in upstream folly for a while now, so let's enable it unconditionally and deshim the experimental/ header. This also allows removing the dead libbfd integration. For this to work, the folly build must be built with and able to find libunwind, which isn't a given when building against libc++ and LLVM libunwind on Ubuntu as it installs includes into a subdirectory, so provide an additional hint for this case.

This allows us to finally have a proper stacktrace rather than raw memory addresses in crash reports, such as:
```
Core dumped: Segmentation fault
Stack trace in /tmp/stacktrace.902095.log
Host: hhvm-jammy-vm
ProcessID: 902095
ThreadID: 281473658339392
ThreadPID: 902095
Name: /usr/local/bin/hhvm
CmdLine: hhvm ../hhvm/hphp/test/quick/dv.php
Type: Segmentation fault
Runtime: hhvm
Version: heads/7.70.0-slack-0-g7be53eff8d22faa0383a128696fae83b224aedd5
DebuggerCount: 0

Arguments: ../hhvm/hphp/test/quick/dv.php
ThreadType: CLI

-------------------------------Treadmill Information----------------------------
Now: 235093382994348
OldestStartTime: 235093373066177
InflightRequestsSize: 1

Active Requests:
  281473658339392 1 235093373066177 (age 9ms) (timeout 0s) CLISession OLDEST

------------------------------------------------------------------------------

CPP Stacktrace:

 # 0  HPHP::jit::FixupMap::processFixupForVMFrame(HPHP::jit::VMFrame)
 # 1  HPHP::jit::FixupMap::fixupWork(HPHP::ActRec*, bool)
 # 2  HPHP::jit::detail::syncVMRegsWork(bool)
 # 3  HPHP::createBacktrace(HPHP::BacktraceArgs const&)
 # 4  HPHP::f_debug_backtrace(long, long)
 # 5  HPHP::throwable_init(HPHP::ObjectData*)
 # 6  HPHP::ObjectData* HPHP::ObjectData::newInstance<false>(HPHP::Class*)
 # 7  HPHP::SystemLib::AllocRuntimeExceptionObject(HPHP::Variant const&)
 # 8  HPHP::SystemLib::throwRuntimeExceptionObject(HPHP::Variant const&)
 # 9  HPHP::throwMissingArgument(HPHP::Func const*, int)

PHP Stacktrace:

 #0  main() called at [/home/mszabo/hhvm/hphp/test/quick/dv.php:28]
 #1  main_entry()

```

[1] a66dd13
[2] c11ad4e
[3] 0e082c4

Pull Request resolved: #9687

Reviewed By: paulbiss

Differential Revision: D88499314

fbshipit-source-id: dc2cbd5cdeab1533ae5fee26b3bf64fc7595cd8c

Author: mszabo-wikia

CMake/HPHPFindLibs.cmake

@@ -274,6 +274,7 @@ endif()
 if (LINUX)
   find_package(systemd REQUIRED)
   find_package(Bpf REQUIRED)
+  find_package(LibUnwind REQUIRED)
 endif()
 
 # This is required by Homebrew's libc. See
@@ -428,6 +429,10 @@ macro(hphp_link target)
   target_link_libraries(${target} ${VISIBILITY} afdt)
   target_link_libraries(${target} ${VISIBILITY} mbfl)
 
+  if (LINUX)
+    target_link_libraries(${target} ${VISIBILITY} ${LIBUNWIND_LIBRARIES})
+  endif()
+
   if (EDITLINE_LIBRARIES)
     target_link_libraries(${target} ${VISIBILITY} ${EDITLINE_LIBRARIES})
   elseif (READLINE_LIBRARY)

build/fbcode_builder/CMake/FindLibUnwind.cmake

@@ -12,7 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-find_path(LIBUNWIND_INCLUDE_DIR NAMES libunwind.h)
+# When using prepackaged LLVM libunwind on Ubuntu, its includes are installed in a subdirectory.
+find_path(LIBUNWIND_INCLUDE_DIR NAMES libunwind.h PATH_SUFFIXES libunwind)
 mark_as_advanced(LIBUNWIND_INCLUDE_DIR)
 
 find_library(LIBUNWIND_LIBRARY NAMES unwind)

hphp/runtime/vm/debug/debug.cpp

@@ -25,15 +25,7 @@
 #include <stdio.h>
 #include <string.h>
 
-#if defined USE_FOLLY_SYMBOLIZER
-
-#include <folly/experimental/symbolizer/Symbolizer.h>
-
-#elif defined HAVE_LIBBFD
-
-#include <bfd.h>
-
-#endif
+#include <folly/debugging/symbolizer/Symbolizer.h>
 
 #include <folly/portability/Unistd.h>
 #include <folly/Demangle.h>
@@ -115,8 +107,6 @@ void DebugInfo::generatePidMapOverlay() {
   };
   std::vector<SymInfo> sorted;
 
-#if defined USE_FOLLY_SYMBOLIZER
-
   auto self = current_executable_path();
   using folly::symbolizer::ElfFile;
   ElfFile file;
@@ -141,51 +131,6 @@ void DebugInfo::generatePidMapOverlay() {
     return false;
   });
 
-#elif defined HAVE_LIBBFD
-
-  auto self = current_executable_path();
-  bfd* abfd = bfd_openr(self.c_str(), nullptr);
-#ifdef BFD_DECOMPRESS
-  abfd->flags |= BFD_DECOMPRESS;
-#endif
-  SCOPE_EXIT { bfd_close(abfd); };
-  char **match = nullptr;
-  if (bfd_check_format(abfd, bfd_archive) ||
-      !bfd_check_format_matches(abfd, bfd_object, &match)) {
-    return;
-  }
-
-  long storage_needed = bfd_get_symtab_upper_bound (abfd);
-
-  if (storage_needed <= 0) return;
-
-  auto symbol_table = (asymbol**)malloc(storage_needed);
-
-  SCOPE_EXIT { free(symbol_table); free(match); };
-
-  long number_of_symbols = bfd_canonicalize_symtab(abfd, symbol_table);
-
-  for (long i = 0; i < number_of_symbols; i++) {
-    auto sym = symbol_table[i];
-    if (sym->flags &
-        (BSF_INDIRECT |
-         BSF_SECTION_SYM |
-         BSF_FILE |
-         BSF_DEBUGGING_RELOC |
-         BSF_OBJECT)) {
-      continue;
-    }
-    auto sec = sym->section;
-    if (!(sec->flags & (SEC_ALLOC|SEC_LOAD|SEC_CODE))) continue;
-    auto addr = sec->vma + sym->value;
-    if (addr < uintptr_t(pidMapOverlayStart) ||
-        addr >= uintptr_t(pidMapOverlayEnd)) {
-      continue;
-    }
-    sorted.push_back(SymInfo{sym->name, addr, 0});
-  }
-#endif // HAVE_LIBBFD
-
   std::sort(
     sorted.begin(), sorted.end(),
     [](const SymInfo& a, const SymInfo& b) {

hphp/util/portability.h

@@ -189,13 +189,6 @@
 
 //////////////////////////////////////////////////////////////////////
 
-#ifdef HHVM_FACEBOOK
-#define USE_FOLLY_SYMBOLIZER 1
-// Linking in libbfd is a gigantic PITA, but if folly symbolizer doesn't
-// work on your platform, you'll need to figure it out.
-#define HAVE_LIBBFD 1
-#endif
-
 #ifndef PACKAGE
 // The value doesn't matter, but it must be defined before you include
 // bfd.h