[tsan] Allow unloading of ignored libraries (#105660)

Allows unloading and reloading of ignored libraries. We don't attempt to
reuse or free memory of unloaded library. So TSan will assert if an
ignored library is reloaded 128 times.

Co-authored-by: Vitaly Buka <[email protected]>

Author: goussepi

compiler-rt/lib/sanitizer_common/sanitizer_libignore.cpp

@@ -32,7 +32,7 @@ void LibIgnore::AddIgnoredLibrary(const char *name_templ) {
   lib->templ = internal_strdup(name_templ);
   lib->name = nullptr;
   lib->real_name = nullptr;
-  lib->loaded = false;
+  lib->range_id = kInvalidCodeRangeId;
 }
 
 void LibIgnore::OnLibraryLoaded(const char *name) {
@@ -43,7 +43,7 @@ void LibIgnore::OnLibraryLoaded(const char *name) {
       buf[0]) {
     for (uptr i = 0; i < count_; i++) {
       Lib *lib = &libs_[i];
-      if (!lib->loaded && (!lib->real_name) &&
+      if (!lib->loaded() && (!lib->real_name) &&
           TemplateMatch(lib->templ, name))
         lib->real_name = internal_strdup(buf.data());
     }
@@ -70,28 +70,31 @@ void LibIgnore::OnLibraryLoaded(const char *name) {
           Die();
         }
         loaded = true;
-        if (lib->loaded)
+        if (lib->loaded())
           continue;
         VReport(1,
                 "Matched called_from_lib suppression '%s' against library"
                 " '%s'\n",
                 lib->templ, mod.full_name());
-        lib->loaded = true;
         lib->name = internal_strdup(mod.full_name());
         const uptr idx =
             atomic_load(&ignored_ranges_count_, memory_order_relaxed);
         CHECK_LT(idx, ARRAY_SIZE(ignored_code_ranges_));
-        ignored_code_ranges_[idx].begin = range.beg;
-        ignored_code_ranges_[idx].end = range.end;
+        ignored_code_ranges_[idx].OnLoad(range.beg, range.end);
+        // Record the index of the ignored range.
+        lib->range_id = idx;
         atomic_store(&ignored_ranges_count_, idx + 1, memory_order_release);
         break;
       }
     }
-    if (lib->loaded && !loaded) {
-      Report("%s: library '%s' that was matched against called_from_lib"
-             " suppression '%s' is unloaded\n",
-             SanitizerToolName, lib->name, lib->templ);
-      Die();
+    if (lib->loaded() && !loaded) {
+      VReport(1,
+              "%s: library '%s' that was matched against called_from_lib"
+              " suppression '%s' is unloaded\n",
+              SanitizerToolName, lib->name, lib->templ);
+      // The library is unloaded so mark the ignored code range as unloaded.
+      ignored_code_ranges_[lib->range_id].OnUnload();
+      lib->range_id = kInvalidCodeRangeId;
     }
   }
 
@@ -110,8 +113,7 @@ void LibIgnore::OnLibraryLoaded(const char *name) {
         const uptr idx =
             atomic_load(&instrumented_ranges_count_, memory_order_relaxed);
         CHECK_LT(idx, ARRAY_SIZE(instrumented_code_ranges_));
-        instrumented_code_ranges_[idx].begin = range.beg;
-        instrumented_code_ranges_[idx].end = range.end;
+        instrumented_code_ranges_[idx].OnLoad(range.beg, range.end);
         atomic_store(&instrumented_ranges_count_, idx + 1,
                      memory_order_release);
       }

compiler-rt/lib/sanitizer_common/sanitizer_libignore.h

@@ -49,25 +49,36 @@ class LibIgnore {
   bool IsPcInstrumented(uptr pc) const;
 
  private:
+  static const uptr kMaxIgnoredRanges = 128;
+  static const uptr kMaxInstrumentedRanges = 1024;
+  static const uptr kMaxLibs = 1024;
+  static const uptr kInvalidCodeRangeId = -1;
+
   struct Lib {
     char *templ;
     char *name;
     char *real_name;  // target of symlink
-    bool loaded;
+    uptr range_id;
+    bool loaded() const { return range_id != kInvalidCodeRangeId; };
   };
 
   struct LibCodeRange {
-    uptr begin;
-    uptr end;
-  };
+    bool IsInRange(uptr pc) const {
+      return (pc >= begin && pc < atomic_load(&end, memory_order_acquire));
+    }
 
-  inline bool IsInRange(uptr pc, const LibCodeRange &range) const {
-    return (pc >= range.begin && pc < range.end);
-  }
+    void OnLoad(uptr b, uptr e) {
+      begin = b;
+      atomic_store(&end, e, memory_order_release);
+    }
 
-  static const uptr kMaxIgnoredRanges = 128;
-  static const uptr kMaxInstrumentedRanges = 1024;
-  static const uptr kMaxLibs = 1024;
+    void OnUnload() { atomic_store(&end, 0, memory_order_release); }
+
+   private:
+    uptr begin;
+    // A value of 0 means the associated module was unloaded.
+    atomic_uintptr_t end;
+  };
 
   // Hot part:
   atomic_uintptr_t ignored_ranges_count_;
@@ -90,7 +101,7 @@ class LibIgnore {
 inline bool LibIgnore::IsIgnored(uptr pc, bool *pc_in_ignored_lib) const {
   const uptr n = atomic_load(&ignored_ranges_count_, memory_order_acquire);
   for (uptr i = 0; i < n; i++) {
-    if (IsInRange(pc, ignored_code_ranges_[i])) {
+    if (ignored_code_ranges_[i].IsInRange(pc)) {
       *pc_in_ignored_lib = true;
       return true;
     }
@@ -104,7 +115,7 @@ inline bool LibIgnore::IsIgnored(uptr pc, bool *pc_in_ignored_lib) const {
 inline bool LibIgnore::IsPcInstrumented(uptr pc) const {
   const uptr n = atomic_load(&instrumented_ranges_count_, memory_order_acquire);
   for (uptr i = 0; i < n; i++) {
-    if (IsInRange(pc, instrumented_code_ranges_[i]))
+    if (instrumented_code_ranges_[i].IsInRange(pc))
       return true;
   }
   return false;

compiler-rt/test/tsan/ignore_lib3.cpp

@@ -3,10 +3,10 @@
 
 // RUN: %clangxx_tsan -O1 %s -DLIB -fPIC -fno-sanitize=thread -shared -o %t-dir/libignore_lib3.so
 // RUN: %clangxx_tsan -O1 %s %link_libcxx_tsan -o %t-dir/executable
-// RUN: %env_tsan_opts=suppressions='%s.supp' %deflake %run %t-dir/executable | FileCheck %s
+// RUN: %env_tsan_opts=suppressions='%s.supp':verbosity=1 %run %t-dir/executable 2>&1 | FileCheck %s
 
 // Tests that unloading of a library matched against called_from_lib suppression
-// causes program crash (this is not supported).
+// is supported.
 
 // Some aarch64 kernels do not support non executable write pages
 // REQUIRES: stable-runtime
@@ -22,18 +22,30 @@
 
 int main(int argc, char **argv) {
   std::string lib = std::string(dirname(argv[0])) + "/libignore_lib3.so";
-  void *h = dlopen(lib.c_str(), RTLD_GLOBAL | RTLD_NOW);
-  dlclose(h);
+  void *h;
+  void (*f)();
+  // Try opening, closing and reopening the ignored lib.
+  for (unsigned int k = 0; k < 2; k++) {
+    h = dlopen(lib.c_str(), RTLD_GLOBAL | RTLD_NOW);
+    if (h == 0)
+      exit(printf("failed to load the library (%d)\n", errno));
+    f = (void (*)())dlsym(h, "libfunc");
+    if (f == 0)
+      exit(printf("failed to find the func (%d)\n", errno));
+    f();
+    dlclose(h);
+  }
   fprintf(stderr, "OK\n");
 }
 
 #else  // #ifdef LIB
 
-extern "C" void libfunc() {
-}
+#  include "ignore_lib_lib.h"
 
 #endif  // #ifdef LIB
 
-// CHECK: ThreadSanitizer: library {{.*}} that was matched against called_from_lib suppression 'ignore_lib3.so' is unloaded
-// CHECK-NOT: OK
-
+// CHECK: Matched called_from_lib suppression 'ignore_lib3.so'
+// CHECK: library '{{.*}}ignore_lib3.so' that was matched against called_from_lib suppression 'ignore_lib3.so' is unloaded
+// CHECK: Matched called_from_lib suppression 'ignore_lib3.so'
+// CHECK: library '{{.*}}ignore_lib3.so' that was matched against called_from_lib suppression 'ignore_lib3.so' is unloaded
+// CHECK: OK