diff options
| -rw-r--r-- | absl/container/btree_test.cc | 9 | ||||
| -rw-r--r-- | absl/debugging/symbolize_elf.inc | 85 | ||||
| -rw-r--r-- | ci/linux_docker_containers.sh | 2 |
3 files changed, 82 insertions, 14 deletions
diff --git a/absl/container/btree_test.cc b/absl/container/btree_test.cc index 1738d291..c5808074 100644 --- a/absl/container/btree_test.cc +++ b/absl/container/btree_test.cc @@ -2463,9 +2463,12 @@ TEST(Btree, EXPECT_THAT(s2, ElementsAre(IsEmpty(), ElementsAre(IsNull()))); } -// GCC 4.9 has a bug in the std::pair constructors that prevents explicit -// conversions between pair types. -#if defined(__clang__) || !defined(__GNUC__) || __GNUC__ >= 5 +// libstdc++ included with GCC 4.9 has a bug in the std::pair constructors that +// prevents explicit conversions between pair types. +// We only run this test for the libstdc++ from GCC 7 or newer because we can't +// reliably check the libstdc++ version prior to that release. +#if !defined(__GLIBCXX__) || \ + (defined(_GLIBCXX_RELEASE) && _GLIBCXX_RELEASE >= 7) TEST(Btree, MapRangeConstructorAndInsertSupportExplicitConversionComparable) { const std::pair<absl::string_view, int> names[] = {{"n1", 1}, {"n2", 2}}; diff --git a/absl/debugging/symbolize_elf.inc b/absl/debugging/symbolize_elf.inc index b7f8663c..2f97cc7e 100644 --- a/absl/debugging/symbolize_elf.inc +++ b/absl/debugging/symbolize_elf.inc @@ -57,6 +57,7 @@ #include <unistd.h> #include <algorithm> +#include <array> #include <atomic> #include <cerrno> #include <cinttypes> @@ -184,6 +185,7 @@ struct ObjFile { fd(-1), elf_type(-1) { SafeMemZero(&elf_header, sizeof(elf_header)); + SafeMemZero(&phdr[0], sizeof(phdr)); } char *filename; @@ -196,6 +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 @@ -1272,6 +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; + int 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; } @@ -1295,23 +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 (int 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 diff --git a/ci/linux_docker_containers.sh b/ci/linux_docker_containers.sh index 82a10ac6..b652071f 100644 --- a/ci/linux_docker_containers.sh +++ b/ci/linux_docker_containers.sh @@ -16,6 +16,6 @@ # Test scripts should source this file to get the identifiers. readonly LINUX_ALPINE_CONTAINER="gcr.io/google.com/absl-177019/alpine:20191016" -readonly LINUX_CLANG_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_clang-latest:20200401" +readonly LINUX_CLANG_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_clang-latest:20200706" readonly LINUX_GCC_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_gcc-latest:20200319" readonly LINUX_GCC_49_CONTAINER="gcr.io/google.com/absl-177019/linux_gcc-4.9:20191018" |