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Diffstat (limited to 'libsanitizer/sanitizer_common/sanitizer_coverage_libcdep.cc')
| -rw-r--r-- | libsanitizer/sanitizer_common/sanitizer_coverage_libcdep.cc | 377 |
1 files changed, 377 insertions, 0 deletions
diff --git a/libsanitizer/sanitizer_common/sanitizer_coverage_libcdep.cc b/libsanitizer/sanitizer_common/sanitizer_coverage_libcdep.cc new file mode 100644 index 00000000000..9b02cd75017 --- /dev/null +++ b/libsanitizer/sanitizer_common/sanitizer_coverage_libcdep.cc @@ -0,0 +1,377 @@ +//===-- sanitizer_coverage.cc ---------------------------------------------===// +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// Sanitizer Coverage. +// This file implements run-time support for a poor man's coverage tool. +// +// Compiler instrumentation: +// For every interesting basic block the compiler injects the following code: +// if (*Guard) { +// __sanitizer_cov(); +// *Guard = 1; +// } +// It's fine to call __sanitizer_cov more than once for a given block. +// +// Run-time: +// - __sanitizer_cov(): record that we've executed the PC (GET_CALLER_PC). +// - __sanitizer_cov_dump: dump the coverage data to disk. +// For every module of the current process that has coverage data +// this will create a file module_name.PID.sancov. The file format is simple: +// it's just a sorted sequence of 4-byte offsets in the module. +// +// Eventually, this coverage implementation should be obsoleted by a more +// powerful general purpose Clang/LLVM coverage instrumentation. +// Consider this implementation as prototype. +// +// FIXME: support (or at least test with) dlclose. +//===----------------------------------------------------------------------===// + +#include "sanitizer_allocator_internal.h" +#include "sanitizer_common.h" +#include "sanitizer_libc.h" +#include "sanitizer_mutex.h" +#include "sanitizer_procmaps.h" +#include "sanitizer_stacktrace.h" +#include "sanitizer_flags.h" + +atomic_uint32_t dump_once_guard; // Ensure that CovDump runs only once. + +// pc_array is the array containing the covered PCs. +// To make the pc_array thread- and async-signal-safe it has to be large enough. +// 128M counters "ought to be enough for anybody" (4M on 32-bit). + +// With coverage_direct=1 in ASAN_OPTIONS, pc_array memory is mapped to a file. +// In this mode, __sanitizer_cov_dump does nothing, and CovUpdateMapping() +// dump current memory layout to another file. + +static bool cov_sandboxed = false; +static int cov_fd = kInvalidFd; +static unsigned int cov_max_block_size = 0; + +namespace __sanitizer { + +class CoverageData { + public: + void Init(); + void BeforeFork(); + void AfterFork(int child_pid); + void Extend(uptr npcs); + void Add(uptr pc); + + uptr *data(); + uptr size(); + + private: + // Maximal size pc array may ever grow. + // We MmapNoReserve this space to ensure that the array is contiguous. + static const uptr kPcArrayMaxSize = FIRST_32_SECOND_64(1 << 22, 1 << 27); + // The amount file mapping for the pc array is grown by. + static const uptr kPcArrayMmapSize = 64 * 1024; + + // pc_array is allocated with MmapNoReserveOrDie and so it uses only as + // much RAM as it really needs. + uptr *pc_array; + // Index of the first available pc_array slot. + atomic_uintptr_t pc_array_index; + // Array size. + atomic_uintptr_t pc_array_size; + // Current file mapped size of the pc array. + uptr pc_array_mapped_size; + // Descriptor of the file mapped pc array. + int pc_fd; + StaticSpinMutex mu; + + void DirectOpen(); + void ReInit(); +}; + +static CoverageData coverage_data; + +void CoverageData::DirectOpen() { + InternalScopedString path(1024); + internal_snprintf((char *)path.data(), path.size(), "%s/%zd.sancov.raw", + common_flags()->coverage_dir, internal_getpid()); + pc_fd = OpenFile(path.data(), true); + if (internal_iserror(pc_fd)) { + Report(" Coverage: failed to open %s for writing\n", path.data()); + Die(); + } + + pc_array_mapped_size = 0; + CovUpdateMapping(); +} + +void CoverageData::Init() { + pc_array = reinterpret_cast<uptr *>( + MmapNoReserveOrDie(sizeof(uptr) * kPcArrayMaxSize, "CovInit")); + pc_fd = kInvalidFd; + if (common_flags()->coverage_direct) { + atomic_store(&pc_array_size, 0, memory_order_relaxed); + atomic_store(&pc_array_index, 0, memory_order_relaxed); + } else { + atomic_store(&pc_array_size, kPcArrayMaxSize, memory_order_relaxed); + atomic_store(&pc_array_index, 0, memory_order_relaxed); + } +} + +void CoverageData::ReInit() { + internal_munmap(pc_array, sizeof(uptr) * kPcArrayMaxSize); + if (pc_fd != kInvalidFd) internal_close(pc_fd); + if (common_flags()->coverage_direct) { + // In memory-mapped mode we must extend the new file to the known array + // size. + uptr size = atomic_load(&pc_array_size, memory_order_relaxed); + Init(); + if (size) Extend(size); + } else { + Init(); + } +} + +void CoverageData::BeforeFork() { + mu.Lock(); +} + +void CoverageData::AfterFork(int child_pid) { + // We are single-threaded so it's OK to release the lock early. + mu.Unlock(); + if (child_pid == 0) ReInit(); +} + +// Extend coverage PC array to fit additional npcs elements. +void CoverageData::Extend(uptr npcs) { + if (!common_flags()->coverage_direct) return; + SpinMutexLock l(&mu); + + if (pc_fd == kInvalidFd) DirectOpen(); + CHECK_NE(pc_fd, kInvalidFd); + + uptr size = atomic_load(&pc_array_size, memory_order_relaxed); + size += npcs * sizeof(uptr); + + if (size > pc_array_mapped_size) { + uptr new_mapped_size = pc_array_mapped_size; + while (size > new_mapped_size) new_mapped_size += kPcArrayMmapSize; + + // Extend the file and map the new space at the end of pc_array. + uptr res = internal_ftruncate(pc_fd, new_mapped_size); + int err; + if (internal_iserror(res, &err)) { + Printf("failed to extend raw coverage file: %d\n", err); + Die(); + } + void *p = MapWritableFileToMemory(pc_array + pc_array_mapped_size, + new_mapped_size - pc_array_mapped_size, + pc_fd, pc_array_mapped_size); + CHECK_EQ(p, pc_array + pc_array_mapped_size); + pc_array_mapped_size = new_mapped_size; + } + + atomic_store(&pc_array_size, size, memory_order_release); +} + +// Simply add the pc into the vector under lock. If the function is called more +// than once for a given PC it will be inserted multiple times, which is fine. +void CoverageData::Add(uptr pc) { + if (!pc_array) return; + uptr idx = atomic_fetch_add(&pc_array_index, 1, memory_order_relaxed); + CHECK_LT(idx * sizeof(uptr), + atomic_load(&pc_array_size, memory_order_acquire)); + pc_array[idx] = pc; +} + +uptr *CoverageData::data() { + return pc_array; +} + +uptr CoverageData::size() { + return atomic_load(&pc_array_index, memory_order_relaxed); +} + +// Block layout for packed file format: header, followed by module name (no +// trailing zero), followed by data blob. +struct CovHeader { + int pid; + unsigned int module_name_length; + unsigned int data_length; +}; + +static void CovWritePacked(int pid, const char *module, const void *blob, + unsigned int blob_size) { + if (cov_fd < 0) return; + unsigned module_name_length = internal_strlen(module); + CovHeader header = {pid, module_name_length, blob_size}; + + if (cov_max_block_size == 0) { + // Writing to a file. Just go ahead. + internal_write(cov_fd, &header, sizeof(header)); + internal_write(cov_fd, module, module_name_length); + internal_write(cov_fd, blob, blob_size); + } else { + // Writing to a socket. We want to split the data into appropriately sized + // blocks. + InternalScopedBuffer<char> block(cov_max_block_size); + CHECK_EQ((uptr)block.data(), (uptr)(CovHeader *)block.data()); + uptr header_size_with_module = sizeof(header) + module_name_length; + CHECK_LT(header_size_with_module, cov_max_block_size); + unsigned int max_payload_size = + cov_max_block_size - header_size_with_module; + char *block_pos = block.data(); + internal_memcpy(block_pos, &header, sizeof(header)); + block_pos += sizeof(header); + internal_memcpy(block_pos, module, module_name_length); + block_pos += module_name_length; + char *block_data_begin = block_pos; + char *blob_pos = (char *)blob; + while (blob_size > 0) { + unsigned int payload_size = Min(blob_size, max_payload_size); + blob_size -= payload_size; + internal_memcpy(block_data_begin, blob_pos, payload_size); + blob_pos += payload_size; + ((CovHeader *)block.data())->data_length = payload_size; + internal_write(cov_fd, block.data(), + header_size_with_module + payload_size); + } + } +} + +// If packed = false: <name>.<pid>.<sancov> (name = module name). +// If packed = true and name == 0: <pid>.<sancov>.<packed>. +// If packed = true and name != 0: <name>.<sancov>.<packed> (name is +// user-supplied). +static int CovOpenFile(bool packed, const char* name) { + InternalScopedBuffer<char> path(1024); + if (!packed) { + CHECK(name); + internal_snprintf((char *)path.data(), path.size(), "%s/%s.%zd.sancov", + common_flags()->coverage_dir, name, internal_getpid()); + } else { + if (!name) + internal_snprintf((char *)path.data(), path.size(), + "%s/%zd.sancov.packed", common_flags()->coverage_dir, + internal_getpid()); + else + internal_snprintf((char *)path.data(), path.size(), "%s/%s.sancov.packed", + common_flags()->coverage_dir, name); + } + uptr fd = OpenFile(path.data(), true); + if (internal_iserror(fd)) { + Report(" SanitizerCoverage: failed to open %s for writing\n", path.data()); + return -1; + } + return fd; +} + +// Dump the coverage on disk. +static void CovDump() { + if (!common_flags()->coverage || common_flags()->coverage_direct) return; +#if !SANITIZER_WINDOWS + if (atomic_fetch_add(&dump_once_guard, 1, memory_order_relaxed)) + return; + uptr size = coverage_data.size(); + InternalMmapVector<u32> offsets(size); + uptr *vb = coverage_data.data(); + uptr *ve = vb + size; + SortArray(vb, size); + MemoryMappingLayout proc_maps(/*cache_enabled*/true); + uptr mb, me, off, prot; + InternalScopedBuffer<char> module(4096); + InternalScopedBuffer<char> path(4096 * 2); + for (int i = 0; + proc_maps.Next(&mb, &me, &off, module.data(), module.size(), &prot); + i++) { + if ((prot & MemoryMappingLayout::kProtectionExecute) == 0) + continue; + while (vb < ve && *vb < mb) vb++; + if (vb >= ve) break; + if (*vb < me) { + offsets.clear(); + const uptr *old_vb = vb; + CHECK_LE(off, *vb); + for (; vb < ve && *vb < me; vb++) { + uptr diff = *vb - (i ? mb : 0) + off; + CHECK_LE(diff, 0xffffffffU); + offsets.push_back(static_cast<u32>(diff)); + } + char *module_name = StripModuleName(module.data()); + if (cov_sandboxed) { + if (cov_fd >= 0) { + CovWritePacked(internal_getpid(), module_name, offsets.data(), + offsets.size() * sizeof(u32)); + VReport(1, " CovDump: %zd PCs written to packed file\n", vb - old_vb); + } + } else { + // One file per module per process. + internal_snprintf((char *)path.data(), path.size(), "%s/%s.%zd.sancov", + common_flags()->coverage_dir, module_name, + internal_getpid()); + int fd = CovOpenFile(false /* packed */, module_name); + if (fd > 0) { + internal_write(fd, offsets.data(), offsets.size() * sizeof(u32)); + internal_close(fd); + VReport(1, " CovDump: %s: %zd PCs written\n", path.data(), + vb - old_vb); + } + } + InternalFree(module_name); + } + } + if (cov_fd >= 0) + internal_close(cov_fd); +#endif // !SANITIZER_WINDOWS +} + +void CovPrepareForSandboxing(__sanitizer_sandbox_arguments *args) { + if (!args) return; + if (!common_flags()->coverage) return; + cov_sandboxed = args->coverage_sandboxed; + if (!cov_sandboxed) return; + cov_fd = args->coverage_fd; + cov_max_block_size = args->coverage_max_block_size; + if (cov_fd < 0) + // Pre-open the file now. The sandbox won't allow us to do it later. + cov_fd = CovOpenFile(true /* packed */, 0); +} + +int MaybeOpenCovFile(const char *name) { + CHECK(name); + if (!common_flags()->coverage) return -1; + return CovOpenFile(true /* packed */, name); +} + +void CovBeforeFork() { + coverage_data.BeforeFork(); +} + +void CovAfterFork(int child_pid) { + coverage_data.AfterFork(child_pid); +} + +} // namespace __sanitizer + +extern "C" { +SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov() { + coverage_data.Add(StackTrace::GetPreviousInstructionPc(GET_CALLER_PC())); +} +SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov_dump() { CovDump(); } +SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov_init() { + coverage_data.Init(); +} +SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov_module_init(uptr npcs) { + if (!common_flags()->coverage || !common_flags()->coverage_direct) return; + if (SANITIZER_ANDROID) { + // dlopen/dlclose interceptors do not work on Android, so we rely on + // Extend() calls to update .sancov.map. + CovUpdateMapping(GET_CALLER_PC()); + } + coverage_data.Extend(npcs); +} +SANITIZER_INTERFACE_ATTRIBUTE +sptr __sanitizer_maybe_open_cov_file(const char *name) { + return MaybeOpenCovFile(name); +} +} // extern "C" |