diff options
Diffstat (limited to 'third_party/abseil_cpp/absl/debugging/symbolize_elf.inc')
| -rw-r--r-- | third_party/abseil_cpp/absl/debugging/symbolize_elf.inc | 104 |
1 files changed, 91 insertions, 13 deletions
diff --git a/third_party/abseil_cpp/absl/debugging/symbolize_elf.inc b/third_party/abseil_cpp/absl/debugging/symbolize_elf.inc index c05424e05b7d..f4d5727bdeb5 100644 --- a/third_party/abseil_cpp/absl/debugging/symbolize_elf.inc +++ b/third_party/abseil_cpp/absl/debugging/symbolize_elf.inc @@ -57,6 +57,7 @@ #include <unistd.h> #include <algorithm> +#include <array> #include <atomic> #include <cerrno> #include <cinttypes> @@ -83,6 +84,12 @@ ABSL_NAMESPACE_BEGIN static char *argv0_value = nullptr; void InitializeSymbolizer(const char *argv0) { +#ifdef ABSL_HAVE_VDSO_SUPPORT + // We need to make sure VDSOSupport::Init() is called before any setuid or + // chroot calls, so InitializeSymbolizer() should be called very early in the + // life of a program. + absl::debugging_internal::VDSOSupport::Init(); +#endif if (argv0_value != nullptr) { free(argv0_value); argv0_value = nullptr; @@ -178,6 +185,7 @@ struct ObjFile { fd(-1), elf_type(-1) { SafeMemZero(&elf_header, sizeof(elf_header)); + SafeMemZero(&phdr[0], sizeof(phdr)); } char *filename; @@ -190,6 +198,10 @@ struct ObjFile { int fd; int elf_type; ElfW(Ehdr) elf_header; + + // PT_LOAD program header describing executable code. + // Normally we expect just one, but SWIFT binaries have two. + std::array<ElfW(Phdr), 2> phdr; }; // Build 4-way associative cache for symbols. Within each cache line, symbols @@ -1266,6 +1278,36 @@ static bool MaybeInitializeObjFile(ObjFile *obj) { ABSL_RAW_LOG(WARNING, "%s: failed to read elf header", obj->filename); return false; } + const int phnum = obj->elf_header.e_phnum; + const int phentsize = obj->elf_header.e_phentsize; + size_t phoff = obj->elf_header.e_phoff; + size_t num_executable_load_segments = 0; + for (int j = 0; j < phnum; j++) { + ElfW(Phdr) phdr; + if (!ReadFromOffsetExact(obj->fd, &phdr, sizeof(phdr), phoff)) { + ABSL_RAW_LOG(WARNING, "%s: failed to read program header %d", + obj->filename, j); + 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. + continue; + } + if (num_executable_load_segments < obj->phdr.size()) { + memcpy(&obj->phdr[num_executable_load_segments++], &phdr, sizeof(phdr)); + } else { + ABSL_RAW_LOG(WARNING, "%s: too many executable LOAD segments", + obj->filename); + break; + } + } + if (num_executable_load_segments == 0) { + // This object has no "r-x" LOAD segments. That's unexpected. + ABSL_RAW_LOG(WARNING, "%s: no executable LOAD segments", obj->filename); + return false; + } } return true; } @@ -1289,23 +1331,52 @@ const char *Symbolizer::GetSymbol(const void *const pc) { int fd = -1; if (obj != nullptr) { if (MaybeInitializeObjFile(obj)) { - if (obj->elf_type == ET_DYN && - reinterpret_cast<uint64_t>(obj->start_addr) >= obj->offset) { + const size_t start_addr = reinterpret_cast<size_t>(obj->start_addr); + if (obj->elf_type == ET_DYN && start_addr >= obj->offset) { // This object was relocated. // // For obj->offset > 0, adjust the relocation since a mapping at offset // X in the file will have a start address of [true relocation]+X. - relocation = reinterpret_cast<ptrdiff_t>(obj->start_addr) - obj->offset; + relocation = start_addr - obj->offset; + + // Note: some binaries have multiple "rx" LOAD segments. 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]; + if (p.p_type != PT_LOAD) { + // We only expect PT_LOADs. This must be PT_NULL that we didn't + // write over (i.e. we exhausted all interesting PT_LOADs). + ABSL_RAW_CHECK(p.p_type == PT_NULL, "unexpected p_type"); + break; + } + if (pc < reinterpret_cast<void *>(start_addr + p.p_memsz)) { + phdr = &p; + break; + } + } + if (phdr == nullptr) { + // That's unexpected. Hope for the best. + ABSL_RAW_LOG( + WARNING, + "%s: unable to find LOAD segment for pc: %p, start_addr: %zx", + obj->filename, pc, start_addr); + } else { + // Adjust relocation in case phdr.p_vaddr != 0. + // This happens for binaries linked with `lld --rosegment`, and for + // binaries linked with BFD `ld -z separate-code`. + relocation -= phdr->p_vaddr - phdr->p_offset; + } } fd = obj->fd; - } - if (GetSymbolFromObjectFile(*obj, pc, relocation, symbol_buf_, - sizeof(symbol_buf_), tmp_buf_, - sizeof(tmp_buf_)) == SYMBOL_FOUND) { - // Only try to demangle the symbol name if it fit into symbol_buf_. - DemangleInplace(symbol_buf_, sizeof(symbol_buf_), tmp_buf_, - sizeof(tmp_buf_)); + if (GetSymbolFromObjectFile(*obj, pc, relocation, symbol_buf_, + sizeof(symbol_buf_), tmp_buf_, + sizeof(tmp_buf_)) == SYMBOL_FOUND) { + // Only try to demangle the symbol name if it fit into symbol_buf_. + DemangleInplace(symbol_buf_, sizeof(symbol_buf_), tmp_buf_, + sizeof(tmp_buf_)); + } } } else { #if ABSL_HAVE_VDSO_SUPPORT @@ -1376,7 +1447,7 @@ int InstallSymbolDecorator(SymbolDecorator decorator, void *arg) { if (!g_decorators_mu.TryLock()) { // Someone else is using decorators. Get out. - return false; + return -2; } int ret = ticket; if (g_num_decorators >= kMaxDecorators) { @@ -1455,7 +1526,7 @@ bool GetFileMappingHint(const void **start, const void **end, uint64_t *offset, bool Symbolize(const void *pc, char *out, int out_size) { // Symbolization is very slow under tsan. - ANNOTATE_IGNORE_READS_AND_WRITES_BEGIN(); + ABSL_ANNOTATE_IGNORE_READS_AND_WRITES_BEGIN(); SAFE_ASSERT(out_size >= 0); debugging_internal::Symbolizer *s = debugging_internal::AllocateSymbolizer(); const char *name = s->GetSymbol(pc); @@ -1474,9 +1545,16 @@ bool Symbolize(const void *pc, char *out, int out_size) { } } debugging_internal::FreeSymbolizer(s); - ANNOTATE_IGNORE_READS_AND_WRITES_END(); + ABSL_ANNOTATE_IGNORE_READS_AND_WRITES_END(); return ok; } ABSL_NAMESPACE_END } // namespace absl + +extern "C" bool AbslInternalGetFileMappingHint(const void **start, + const void **end, uint64_t *offset, + const char **filename) { + return absl::debugging_internal::GetFileMappingHint(start, end, offset, + filename); +} |