[asancov] Write coverage directly to a memory-mapped file.

This way does not require a __sanitizer_cov_dump() call. That's
important on Android, where apps can be killed at arbitrary time.

We write raw PCs to disk instead of module offsets; we also write
memory layout to a separate file. This increases dump size by the
factor of 2 on 64-bit systems.

llvm-svn: 209653

1 files changed, 97 insertions, 0 deletions

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc
new file mode 100644
index 00000000000..75f6162d185
--- /dev/null
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_mapping_libcdep.cc
@@ -0,0 +1,97 @@
+//===-- sanitizer_coverage_mapping.cc -------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Mmap-based implementation of sanitizer coverage.
+//
+// This is part of the implementation of code coverage that does not require
+// __sanitizer_cov_dump() call. Data is stored in 2 files per process.
+//
+// $pid.sancov.map describes process memory layout in the following text-based
+// format:
+// <pointer size in bits>  // 1 line, 32 or 64
+// <mapping start> <mapping end> <base address> <dso name> // repeated
+// ...
+// Mapping lines are NOT sorted. This file is updated every time memory layout
+// is changed (i.e. in dlopen() and dlclose() interceptors).
+//
+// $pid.sancov.raw is a binary dump of PC values, sizeof(uptr) each. Again, not
+// sorted. This file is extended by 64Kb at a time and mapped into memory. It
+// contains one or more 0 words at the end, up to the next 64Kb aligned offset.
+//
+// To convert these 2 files to the usual .sancov format, run sancov.py rawunpack
+// $pid.sancov.raw.
+//
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_allocator_internal.h"
+#include "sanitizer_libc.h"
+#include "sanitizer_procmaps.h"
+
+namespace __sanitizer {
+
+static const uptr kMaxNumberOfModules = 1 << 14;
+
+void CovUpdateMapping() {
+  if (!common_flags()->coverage || !common_flags()->coverage_direct) return;
+
+  int err;
+  InternalScopedString tmp_path(64);
+  internal_snprintf((char *)tmp_path.data(), tmp_path.size(),
+                    "%zd.sancov.map.tmp", internal_getpid());
+  uptr map_fd = OpenFile(tmp_path.data(), true);
+  if (internal_iserror(map_fd)) {
+    Report(" Coverage: failed to open %s for writing\n", tmp_path.data());
+    Die();
+  }
+
+  InternalScopedBuffer<char> modules_data(kMaxNumberOfModules *
+                                          sizeof(LoadedModule));
+  LoadedModule *modules = (LoadedModule *)modules_data.data();
+  CHECK(modules);
+  int n_modules = GetListOfModules(modules, kMaxNumberOfModules,
+                                   /* filter */ 0);
+
+  InternalScopedString line(4096);
+  line.append("%d\n", sizeof(uptr) * 8);
+  uptr res = internal_write(map_fd, line.data(), line.length());
+  if (internal_iserror(res, &err)) {
+    Printf("sancov.map write failed: %d\n", err);
+    Die();
+  }
+  line.clear();
+
+  for (int i = 0; i < n_modules; ++i) {
+    char *module_name = StripModuleName(modules[i].full_name());
+    for (unsigned j = 0; j < modules[i].n_ranges(); ++j) {
+      line.append("%zx %zx %zx %s\n", modules[i].address_range_start(j),
+                  modules[i].address_range_end(j), modules[i].base_address(),
+                  module_name);
+      res = internal_write(map_fd, line.data(), line.length());
+      if (internal_iserror(res, &err)) {
+        Printf("sancov.map write failed: %d\n", err);
+        Die();
+      }
+      line.clear();
+    }
+    InternalFree(module_name);
+  }
+
+  internal_close(map_fd);
+
+  InternalScopedString path(64);
+  internal_snprintf((char *)path.data(), path.size(), "%zd.sancov.map",
+                    internal_getpid());
+  res = internal_rename(tmp_path.data(), path.data());
+  if (internal_iserror(res, &err)) {
+    Printf("sancov.map rename failed: %d\n", err);
+    Die();
+  }
+}
+
+}  // namespace __sanitizer