[asan] Fix dead stripping of globals on Linux (compiler-rt).

Third attempt. See the description of the corresponding commit in
LLVM for more details.

llvm-svn: 301588

compiler-rt/lib/asan/asan_globals.cc

@@ -332,6 +332,26 @@ void __asan_unregister_image_globals(uptr *flag) {
   *flag = 0;
 }
 
+void __asan_register_elf_globals(uptr *flag, void *start, void *stop) {
+  if (*flag) return;
+  if (!start) return;
+  CHECK_EQ(0, ((uptr)stop - (uptr)start) % sizeof(__asan_global));
+  __asan_global *globals_start = (__asan_global*)start;
+  __asan_global *globals_stop = (__asan_global*)stop;
+  __asan_register_globals(globals_start, globals_stop - globals_start);
+  *flag = 1;
+}
+
+void __asan_unregister_elf_globals(uptr *flag, void *start, void *stop) {
+  if (!*flag) return;
+  if (!start) return;
+  CHECK_EQ(0, ((uptr)stop - (uptr)start) % sizeof(__asan_global));
+  __asan_global *globals_start = (__asan_global*)start;
+  __asan_global *globals_stop = (__asan_global*)stop;
+  __asan_unregister_globals(globals_start, globals_stop - globals_start);
+  *flag = 0;
+}
+
 // Register an array of globals.
 void __asan_register_globals(__asan_global *globals, uptr n) {
   if (!flags()->report_globals) return;

compiler-rt/lib/asan/asan_interface.inc

@@ -64,6 +64,7 @@ INTERFACE_FUNCTION(__asan_poison_stack_memory)
 INTERFACE_FUNCTION(__asan_print_accumulated_stats)
 INTERFACE_FUNCTION(__asan_region_is_poisoned)
 INTERFACE_FUNCTION(__asan_register_globals)
+INTERFACE_FUNCTION(__asan_register_elf_globals)
 INTERFACE_FUNCTION(__asan_register_image_globals)
 INTERFACE_FUNCTION(__asan_report_error)
 INTERFACE_FUNCTION(__asan_report_exp_load1)
@@ -149,6 +150,7 @@ INTERFACE_FUNCTION(__asan_unpoison_intra_object_redzone)
 INTERFACE_FUNCTION(__asan_unpoison_memory_region)
 INTERFACE_FUNCTION(__asan_unpoison_stack_memory)
 INTERFACE_FUNCTION(__asan_unregister_globals)
+INTERFACE_FUNCTION(__asan_unregister_elf_globals)
 INTERFACE_FUNCTION(__asan_unregister_image_globals)
 INTERFACE_FUNCTION(__asan_version_mismatch_check_v8)
 INTERFACE_FUNCTION(__sanitizer_finish_switch_fiber)

compiler-rt/lib/asan/asan_interface_internal.h

@@ -67,6 +67,11 @@ extern "C" {
   SANITIZER_INTERFACE_ATTRIBUTE
   void __asan_unregister_image_globals(uptr *flag);
 
+  SANITIZER_INTERFACE_ATTRIBUTE
+  void __asan_register_elf_globals(uptr *flag, void *start, void *stop);
+  SANITIZER_INTERFACE_ATTRIBUTE
+  void __asan_unregister_elf_globals(uptr *flag, void *start, void *stop);
+
   // These two functions should be called by the instrumented code.
   // 'globals' is an array of structures describing 'n' globals.
   SANITIZER_INTERFACE_ATTRIBUTE

compiler-rt/test/asan/CMakeLists.txt

@@ -22,7 +22,7 @@ endmacro()
 set(ASAN_TEST_DEPS ${SANITIZER_COMMON_LIT_TEST_DEPS})
 if(NOT COMPILER_RT_STANDALONE_BUILD)
   list(APPEND ASAN_TEST_DEPS asan)
-  if(WIN32 AND COMPILER_RT_HAS_LLD)
+  if(NOT APPLE AND COMPILER_RT_HAS_LLD)
     list(APPEND ASAN_TEST_DEPS
       lld
     )

compiler-rt/test/asan/TestCases/Linux/global-overflow-bfd.cc

@@ -0,0 +1,18 @@
+// Test that gc-sections-friendly instrumentation of globals does not introduce
+// false negatives with the BFD linker.
+// RUN: %clangxx_asan -fuse-ld=bfd -Wl,-gc-sections -ffunction-sections -fdata-sections -O0 %s -o %t && not %run %t 2>&1 | FileCheck %s
+
+#include <string.h>
+int main(int argc, char **argv) {
+  static char XXX[10];
+  static char YYY[10];
+  static char ZZZ[10];
+  memset(XXX, 0, 10);
+  memset(YYY, 0, 10);
+  memset(ZZZ, 0, 10);
+  int res = YYY[argc * 10];  // BOOOM
+  // CHECK: {{READ of size 1 at}}
+  // CHECK: {{located 0 bytes to the right of global variable}}
+  res += XXX[argc] + ZZZ[argc];
+  return res;
+}

compiler-rt/test/asan/TestCases/Linux/global-overflow-lld.cc

@@ -0,0 +1,19 @@
+// Test that gc-sections-friendly instrumentation of globals does not introduce
+// false negatives with the LLD linker.
+// RUN: %clangxx_asan -fuse-ld=lld -Wl,-gc-sections -ffunction-sections -fdata-sections -O0 %s -o %t && not %run %t 2>&1 | FileCheck %s
+// REQUIRES: lld
+
+#include <string.h>
+int main(int argc, char **argv) {
+  static char XXX[10];
+  static char YYY[10];
+  static char ZZZ[10];
+  memset(XXX, 0, 10);
+  memset(YYY, 0, 10);
+  memset(ZZZ, 0, 10);
+  int res = YYY[argc * 10];  // BOOOM
+  // CHECK: {{READ of size 1 at}}
+  // CHECK: {{located 0 bytes to the right of global variable}}
+  res += XXX[argc] + ZZZ[argc];
+  return res;
+}

compiler-rt/test/asan/TestCases/Linux/globals-gc-sections-lld.cc

@@ -0,0 +1,15 @@
+// RUN: %clangxx_asan %s -o %t -Wl,--gc-sections -fuse-ld=lld -ffunction-sections -fdata-sections -mllvm -asan-globals=0
+// RUN: %clangxx_asan %s -o %t -Wl,--gc-sections -fuse-ld=lld -ffunction-sections -fdata-sections -mllvm -asan-globals=1
+
+// https://code.google.com/p/address-sanitizer/issues/detail?id=260
+// REQUIRES: lld
+
+int undefined();
+
+// On i386 clang adds --export-dynamic when linking with ASan, which adds all
+// non-hidden globals to GC roots.
+__attribute__((visibility("hidden"))) int (*unused)() = undefined;
+
+int main() {
+        return 0;
+}