[LSan] Use __tls_get_addr interceptor to keep track of dynamic TLS.

Summary:
We have a way to keep track of allocated DTLS segments: let's use it
in LSan. Although this code is fragile and relies on glibc
implementation details, in some cases it proves to be better than
existing way of tracking DTLS in LSan: marking as "reachable" all
memory chunks allocated directly by "ld".

The plan is to eventually get rid of the latter, once we are sure
it's safe to remove.

Reviewers: kcc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D16164

llvm-svn: 257785

6 files changed, 50 insertions, 17 deletions

diff --git a/compiler-rt/lib/lsan/lsan.cc b/compiler-rt/lib/lsan/lsan.cc
index f3e6ad7c9cb..9c6735919b8 100644
--- a/compiler-rt/lib/lsan/lsan.cc
+++ b/compiler-rt/lib/lsan/lsan.cc
@@ -43,6 +43,7 @@ static void InitializeFlags() {
     cf.CopyFrom(*common_flags());
     cf.external_symbolizer_path = GetEnv("LSAN_SYMBOLIZER_PATH");
     cf.malloc_context_size = 30;
+    cf.intercept_tls_get_addr = true;
     cf.detect_leaks = true;
     cf.exitcode = 23;
     OverrideCommonFlags(cf);
diff --git a/compiler-rt/lib/lsan/lsan_common.cc b/compiler-rt/lib/lsan/lsan_common.cc
index 1cffac44395..a7eab15b826 100644
--- a/compiler-rt/lib/lsan/lsan_common.cc
+++ b/compiler-rt/lib/lsan/lsan_common.cc
@@ -23,6 +23,7 @@
 #include "sanitizer_common/sanitizer_stacktrace.h"
 #include "sanitizer_common/sanitizer_suppressions.h"
 #include "sanitizer_common/sanitizer_report_decorator.h"
+#include "sanitizer_common/sanitizer_tls_get_addr.h"
 
 #if CAN_SANITIZE_LEAKS
 namespace __lsan {
@@ -185,9 +186,10 @@ static void ProcessThreads(SuspendedThreadsList const &suspended_threads,
     uptr os_id = static_cast<uptr>(suspended_threads.GetThreadID(i));
     LOG_THREADS("Processing thread %d.\n", os_id);
     uptr stack_begin, stack_end, tls_begin, tls_end, cache_begin, cache_end;
+    DTLS *dtls;
     bool thread_found = GetThreadRangesLocked(os_id, &stack_begin, &stack_end,
                                               &tls_begin, &tls_end,
-                                              &cache_begin, &cache_end);
+                                              &cache_begin, &cache_end, &dtls);
     if (!thread_found) {
       // If a thread can't be found in the thread registry, it's probably in the
       // process of destruction. Log this event and move on.
@@ -238,6 +240,17 @@ static void ProcessThreads(SuspendedThreadsList const &suspended_threads,
         if (tls_end > cache_end)
           ScanRangeForPointers(cache_end, tls_end, frontier, "TLS", kReachable);
       }
+      if (dtls) {
+        for (uptr j = 0; j < dtls->dtv_size; ++j) {
+          uptr dtls_beg = dtls->dtv[j].beg;
+          uptr dtls_end = dtls_beg + dtls->dtv[j].size;
+          if (dtls_beg < dtls_end) {
+            LOG_THREADS("DTLS %zu at %p-%p.\n", j, dtls_beg, dtls_end);
+            ScanRangeForPointers(dtls_beg, dtls_end, frontier, "DTLS",
+                                 kReachable);
+          }
+        }
+      }
     }
   }
 }
diff --git a/compiler-rt/lib/lsan/lsan_common.h b/compiler-rt/lib/lsan/lsan_common.h
index 0dfd0d4c989..e09151e8cba 100644
--- a/compiler-rt/lib/lsan/lsan_common.h
+++ b/compiler-rt/lib/lsan/lsan_common.h
@@ -31,6 +31,7 @@
 
 namespace __sanitizer {
 class FlagParser;
+struct DTLS;
 }
 
 namespace __lsan {
@@ -141,8 +142,8 @@ bool WordIsPoisoned(uptr addr);
 void LockThreadRegistry();
 void UnlockThreadRegistry();
 bool GetThreadRangesLocked(uptr os_id, uptr *stack_begin, uptr *stack_end,
-                           uptr *tls_begin, uptr *tls_end,
-                           uptr *cache_begin, uptr *cache_end);
+                           uptr *tls_begin, uptr *tls_end, uptr *cache_begin,
+                           uptr *cache_end, DTLS **dtls);
 void ForEachExtraStackRange(uptr os_id, RangeIteratorCallback callback,
                             void *arg);
 // If called from the main thread, updates the main thread's TID in the thread
diff --git a/compiler-rt/lib/lsan/lsan_interceptors.cc b/compiler-rt/lib/lsan/lsan_interceptors.cc
index be0d0ddc282..5921e06ab25 100644
--- a/compiler-rt/lib/lsan/lsan_interceptors.cc
+++ b/compiler-rt/lib/lsan/lsan_interceptors.cc
@@ -20,6 +20,7 @@
 #include "sanitizer_common/sanitizer_internal_defs.h"
 #include "sanitizer_common/sanitizer_linux.h"
 #include "sanitizer_common/sanitizer_platform_limits_posix.h"
+#include "sanitizer_common/sanitizer_tls_get_addr.h"
 #include "lsan.h"
 #include "lsan_allocator.h"
 #include "lsan_thread.h"
@@ -104,6 +105,14 @@ INTERCEPTOR(int, posix_memalign, void **memptr, uptr alignment, uptr size) {
   return 0;
 }
 
+INTERCEPTOR(void *, __libc_memalign, uptr alignment, uptr size) {
+  ENSURE_LSAN_INITED;
+  GET_STACK_TRACE_MALLOC;
+  void *res = Allocate(stack, size, alignment, kAlwaysClearMemory);
+  DTLS_on_libc_memalign(res, size);
+  return res;
+}
+
 INTERCEPTOR(void*, valloc, uptr size) {
   ENSURE_LSAN_INITED;
   GET_STACK_TRACE_MALLOC;
@@ -174,11 +183,6 @@ void operator delete[](void *ptr, std::nothrow_t const &) {
   OPERATOR_DELETE_BODY;
 }
 
-// We need this to intercept the __libc_memalign calls that are used to
-// allocate dynamic TLS space in ld-linux.so.
-INTERCEPTOR(void *, __libc_memalign, uptr align, uptr s)
-    ALIAS(WRAPPER_NAME(memalign));
-
 ///// Thread initialization and finalization. /////
 
 static unsigned g_thread_finalize_key;
diff --git a/compiler-rt/lib/lsan/lsan_thread.cc b/compiler-rt/lib/lsan/lsan_thread.cc
index 10ac2c9f499..8bd6d90edc9 100644
--- a/compiler-rt/lib/lsan/lsan_thread.cc
+++ b/compiler-rt/lib/lsan/lsan_thread.cc
@@ -17,6 +17,7 @@
 #include "sanitizer_common/sanitizer_common.h"
 #include "sanitizer_common/sanitizer_placement_new.h"
 #include "sanitizer_common/sanitizer_thread_registry.h"
+#include "sanitizer_common/sanitizer_tls_get_addr.h"
 #include "lsan_allocator.h"
 
 namespace __lsan {
@@ -49,18 +50,20 @@ void SetCurrentThread(u32 tid) {
 }
 
 ThreadContext::ThreadContext(int tid)
-  : ThreadContextBase(tid),
-    stack_begin_(0),
-    stack_end_(0),
-    cache_begin_(0),
-    cache_end_(0),
-    tls_begin_(0),
-    tls_end_(0) {}
+    : ThreadContextBase(tid),
+      stack_begin_(0),
+      stack_end_(0),
+      cache_begin_(0),
+      cache_end_(0),
+      tls_begin_(0),
+      tls_end_(0),
+      dtls_(nullptr) {}
 
 struct OnStartedArgs {
   uptr stack_begin, stack_end,
        cache_begin, cache_end,
        tls_begin, tls_end;
+  DTLS *dtls;
 };
 
 void ThreadContext::OnStarted(void *arg) {
@@ -71,10 +74,12 @@ void ThreadContext::OnStarted(void *arg) {
   tls_end_ = args->tls_end;
   cache_begin_ = args->cache_begin;
   cache_end_ = args->cache_end;
+  dtls_ = args->dtls;
 }
 
 void ThreadContext::OnFinished() {
   AllocatorThreadFinish();
+  DTLS_Destroy();
 }
 
 u32 ThreadCreate(u32 parent_tid, uptr user_id, bool detached) {
@@ -91,6 +96,7 @@ void ThreadStart(u32 tid, uptr os_id) {
   args.stack_end = args.stack_begin + stack_size;
   args.tls_end = args.tls_begin + tls_size;
   GetAllocatorCacheRange(&args.cache_begin, &args.cache_end);
+  args.dtls = DTLS_Get();
   thread_registry->StartThread(tid, os_id, &args);
 }
 
@@ -131,8 +137,8 @@ void EnsureMainThreadIDIsCorrect() {
 ///// Interface to the common LSan module. /////
 
 bool GetThreadRangesLocked(uptr os_id, uptr *stack_begin, uptr *stack_end,
-                           uptr *tls_begin, uptr *tls_end,
-                           uptr *cache_begin, uptr *cache_end) {
+                           uptr *tls_begin, uptr *tls_end, uptr *cache_begin,
+                           uptr *cache_end, DTLS **dtls) {
   ThreadContext *context = static_cast<ThreadContext *>(
       thread_registry->FindThreadContextByOsIDLocked(os_id));
   if (!context) return false;
@@ -142,6 +148,7 @@ bool GetThreadRangesLocked(uptr os_id, uptr *stack_begin, uptr *stack_end,
   *tls_end = context->tls_end();
   *cache_begin = context->cache_begin();
   *cache_end = context->cache_end();
+  *dtls = context->dtls();
   return true;
 }
 
diff --git a/compiler-rt/lib/lsan/lsan_thread.h b/compiler-rt/lib/lsan/lsan_thread.h
index 99e2c1d5e64..10b7b5796c5 100644
--- a/compiler-rt/lib/lsan/lsan_thread.h
+++ b/compiler-rt/lib/lsan/lsan_thread.h
@@ -17,6 +17,10 @@
 
 #include "sanitizer_common/sanitizer_thread_registry.h"
 
+namespace __sanitizer {
+struct DTLS;
+}
+
 namespace __lsan {
 
 class ThreadContext : public ThreadContextBase {
@@ -30,10 +34,13 @@ class ThreadContext : public ThreadContextBase {
   uptr tls_end() { return tls_end_; }
   uptr cache_begin() { return cache_begin_; }
   uptr cache_end() { return cache_end_; }
+  DTLS *dtls() { return dtls_; }
+
  private:
   uptr stack_begin_, stack_end_,
        cache_begin_, cache_end_,
        tls_begin_, tls_end_;
+  DTLS *dtls_;
 };
 
 void InitializeThreadRegistry();