[sancov] Define delimiters for sanitizer coverage's binary section on Windows.

Marcos Pividori · Marcos Pividori · commit c1f8a82491db · 2017-02-02T23:02:15.000Z
On Windows, the symbols "___stop___sancov_guards" and "___start___sancov_guards" are not defined automatically. So, we need to take a different approach. We define 3 sections: ".SCOV$A", ".SCOV$M" and ".SCOV$Z". Section ".SCOV$A" will only hold a variable ___start___sancov_guard. Section ".SCOV$M" will hold the main data. Section ".SCOV$Z" will only hold a variable ___stop___sancov_guards. When linking, they will be merged sorted by the characters after the $, so we can use the pointers of the variables ___[start|stop]___sancov_guard to know the actual range of addresses of that section. ___[start|stop]___sancov_guard should be defined only once per module. On Windows, we have 2 different cases: + When considering a shared runtime: All the modules, main executable and dlls, are linked to an auxiliary static library dynamic_runtime_thunk.lib. Because of that, we include the delimiters in `SancovDynamicRuntimeThunk`. + When considering a static runtime: The main executable in linked to the static runtime library. All the dlls are linked to an auxiliary static library dll_thunk. Because of that, we include the delimiter to both `SancovDllThunk` and `SANITIZER_LIBCDEP_SOURCES` (which is included in the static runtime lib). Differential Revision: https://reviews.llvm.org/D28435 llvm-svn: 293959
diff --git a/compiler-rt/lib/sanitizer_common/CMakeLists.txt b/compiler-rt/lib/sanitizer_common/CMakeLists.txt
@@ -56,6 +56,7 @@ set(SANITIZER_LIBCDEP_SOURCES
   sanitizer_coverage_libcdep.cc
   sanitizer_coverage_libcdep_new.cc
   sanitizer_coverage_mapping_libcdep.cc
+  sanitizer_coverage_win_sections.cc
   sanitizer_linux_libcdep.cc
   sanitizer_posix_libcdep.cc
   sanitizer_stacktrace_libcdep.cc
@@ -211,6 +212,7 @@ if(MSVC)
     ${SANITIZER_COMMON_SUPPORTED_OS}
     ARCHS ${SANITIZER_COMMON_SUPPORTED_ARCH}
     SOURCES sanitizer_coverage_win_dll_thunk.cc
+            sanitizer_coverage_win_sections.cc
     CFLAGS ${SANITIZER_CFLAGS} -DSANITIZER_DLL_THUNK
     DEFS ${SANITIZER_COMMON_DEFINITIONS})
 
@@ -230,6 +232,7 @@ if(MSVC)
     ${SANITIZER_COMMON_SUPPORTED_OS}
     ARCHS ${SANITIZER_COMMON_SUPPORTED_ARCH}
     SOURCES sanitizer_coverage_win_dynamic_runtime_thunk.cc
+            sanitizer_coverage_win_sections.cc
     CFLAGS ${SANITIZER_CFLAGS} ${DYNAMIC_RUNTIME_THUNK_CFLAGS}
     DEFS ${SANITIZER_COMMON_DEFINITIONS})
 endif()
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_coverage_win_sections.cc b/compiler-rt/lib/sanitizer_common/sanitizer_coverage_win_sections.cc
@@ -0,0 +1,22 @@
+//===-- sanitizer_coverage_win_sections.cc --------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines delimiters for Sanitizer Coverage's section.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_WINDOWS
+#include <stdint.h>
+#pragma section(".SCOV$A", read, write)  // NOLINT
+#pragma section(".SCOV$Z", read, write)  // NOLINT
+extern "C" {
+__declspec(allocate(".SCOV$A")) uint32_t __start___sancov_guards = 0;
+__declspec(allocate(".SCOV$Z")) uint32_t __stop___sancov_guards = 0;
+}
+#endif // SANITIZER_WINDOWS
