forked from OSchip/llvm-project
130 lines
4.6 KiB
C++
130 lines
4.6 KiB
C++
//===-- sanitizer_coverage.cc ---------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Sanitizer Coverage.
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// This file implements run-time support for a poor man's coverage tool.
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//
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// Compiler instrumentation:
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// For every interesting basic block the compiler injects the following code:
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// if (*Guard) {
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// __sanitizer_cov();
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// *Guard = 1;
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// }
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// It's fine to call __sanitizer_cov more than once for a given block.
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//
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// Run-time:
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// - __sanitizer_cov(): record that we've executed the PC (GET_CALLER_PC).
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// - __sanitizer_cov_dump: dump the coverage data to disk.
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// For every module of the current process that has coverage data
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// this will create a file module_name.PID.sancov. The file format is simple:
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// it's just a sorted sequence of 4-byte offsets in the module.
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//
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// Eventually, this coverage implementation should be obsoleted by a more
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// powerful general purpose Clang/LLVM coverage instrumentation.
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// Consider this implementation as prototype.
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//
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// FIXME: support (or at least test with) dlclose.
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//===----------------------------------------------------------------------===//
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#include "sanitizer_allocator_internal.h"
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#include "sanitizer_common.h"
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#include "sanitizer_libc.h"
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#include "sanitizer_mutex.h"
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#include "sanitizer_procmaps.h"
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#include "sanitizer_stacktrace.h"
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#include "sanitizer_flags.h"
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atomic_uint32_t dump_once_guard; // Ensure that CovDump runs only once.
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// pc_array is the array containing the covered PCs.
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// To make the pc_array thread- and AS- safe it has to be large enough.
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// 128M counters "ought to be enough for anybody" (4M on 32-bit).
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// pc_array is allocated with MmapNoReserveOrDie and so it uses only as
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// much RAM as it really needs.
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static const uptr kPcArraySize = FIRST_32_SECOND_64(1 << 22, 1 << 27);
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static uptr *pc_array;
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static atomic_uintptr_t pc_array_index;
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namespace __sanitizer {
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// Simply add the pc into the vector under lock. If the function is called more
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// than once for a given PC it will be inserted multiple times, which is fine.
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static void CovAdd(uptr pc) {
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if (!pc_array) return;
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uptr idx = atomic_fetch_add(&pc_array_index, 1, memory_order_relaxed);
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CHECK_LT(idx, kPcArraySize);
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pc_array[idx] = pc;
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}
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void CovInit() {
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pc_array = reinterpret_cast<uptr *>(
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MmapNoReserveOrDie(sizeof(uptr) * kPcArraySize, "CovInit"));
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}
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static inline bool CompareLess(const uptr &a, const uptr &b) {
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return a < b;
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}
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// Dump the coverage on disk.
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void CovDump() {
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#if !SANITIZER_WINDOWS
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if (atomic_fetch_add(&dump_once_guard, 1, memory_order_relaxed))
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return;
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uptr size = atomic_load(&pc_array_index, memory_order_relaxed);
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InternalSort(&pc_array, size, CompareLess);
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InternalMmapVector<u32> offsets(size);
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const uptr *vb = pc_array;
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const uptr *ve = vb + size;
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MemoryMappingLayout proc_maps(/*cache_enabled*/false);
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uptr mb, me, off, prot;
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InternalScopedBuffer<char> module(4096);
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InternalScopedBuffer<char> path(4096 * 2);
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for (int i = 0;
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proc_maps.Next(&mb, &me, &off, module.data(), module.size(), &prot);
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i++) {
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if ((prot & MemoryMappingLayout::kProtectionExecute) == 0)
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continue;
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while (vb < ve && *vb < mb) vb++;
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if (vb >= ve) break;
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if (*vb < me) {
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offsets.clear();
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const uptr *old_vb = vb;
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CHECK_LE(off, *vb);
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for (; vb < ve && *vb < me; vb++) {
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uptr diff = *vb - (i ? mb : 0) + off;
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CHECK_LE(diff, 0xffffffffU);
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offsets.push_back(static_cast<u32>(diff));
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}
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char *module_name = StripModuleName(module.data());
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internal_snprintf((char *)path.data(), path.size(), "%s.%zd.sancov",
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module_name, internal_getpid());
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InternalFree(module_name);
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uptr fd = OpenFile(path.data(), true);
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if (internal_iserror(fd)) {
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Report(" CovDump: failed to open %s for writing\n", path.data());
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} else {
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internal_write(fd, offsets.data(), offsets.size() * sizeof(u32));
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internal_close(fd);
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VReport(1, " CovDump: %s: %zd PCs written\n", path.data(), vb - old_vb);
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}
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}
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}
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#endif // !SANITIZER_WINDOWS
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}
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} // namespace __sanitizer
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extern "C" {
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SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov() {
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CovAdd(StackTrace::GetPreviousInstructionPc(GET_CALLER_PC()));
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}
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SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov_dump() { CovDump(); }
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SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_cov_init() { CovInit(); }
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} // extern "C"
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