[compiler-rt] r257789 - [LSan] Add "use_ld_allocations" flag to disable old way of DTLS handling.

[Alexey Samsonov via llvm-commits]

Author: samsonov
Date: Thu Jan 14 13:16:05 2016
New Revision: 257789

URL: http://llvm.org/viewvc/llvm-project?rev=257789&view=rev
Log:
[LSan] Add "use_ld_allocations" flag to disable old way of DTLS handling.

This flag allows to disable old way of determining dynamic TLS by
filtering out allocations from dynamic linker. This will be eventually
superseded by __tls_get_addr interceptor (see r257785), after we:
1) Test it in several supported environments
2) Deal with existing problems (currently we can't find a pointer to
  DTV which is calloc()-ed in pthread_create).

Modified:
    compiler-rt/trunk/lib/lsan/lsan_common_linux.cc
    compiler-rt/trunk/lib/lsan/lsan_flags.inc
    compiler-rt/trunk/test/lsan/TestCases/use_tls_dynamic.cc

Modified: compiler-rt/trunk/lib/lsan/lsan_common_linux.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/lsan/lsan_common_linux.cc?rev=257789&r1=257788&r2=257789&view=diff
==============================================================================
--- compiler-rt/trunk/lib/lsan/lsan_common_linux.cc (original)
+++ compiler-rt/trunk/lib/lsan/lsan_common_linux.cc Thu Jan 14 13:16:05 2016
@@ -100,6 +100,7 @@ static uptr GetCallerPC(u32 stack_id, St
 struct ProcessPlatformAllocParam {
   Frontier *frontier;
   StackDepotReverseMap *stack_depot_reverse_map;
+  bool skip_linker_allocations;
 };
 
 // ForEachChunk callback. Identifies unreachable chunks which must be treated as
@@ -117,7 +118,8 @@ static void ProcessPlatformSpecificAlloc
       caller_pc = GetCallerPC(stack_id, param->stack_depot_reverse_map);
     // If caller_pc is unknown, this chunk may be allocated in a coroutine. Mark
     // it as reachable, as we can't properly report its allocation stack anyway.
-    if (caller_pc == 0 || linker->containsAddress(caller_pc)) {
+    if (caller_pc == 0 || (param->skip_linker_allocations &&
+                           linker->containsAddress(caller_pc))) {
       m.set_tag(kReachable);
       param->frontier->push_back(chunk);
     }
@@ -142,10 +144,12 @@ static void ProcessPlatformSpecificAlloc
 // guaranteed to include all dynamic TLS blocks (and possibly other allocations
 // which we don't care about).
 void ProcessPlatformSpecificAllocations(Frontier *frontier) {
-  if (!flags()->use_tls) return;
-  if (!linker) return;
   StackDepotReverseMap stack_depot_reverse_map;
-  ProcessPlatformAllocParam arg = {frontier, &stack_depot_reverse_map};
+  ProcessPlatformAllocParam arg;
+  arg.frontier = frontier;
+  arg.stack_depot_reverse_map = &stack_depot_reverse_map;
+  arg.skip_linker_allocations =
+      flags()->use_tls && flags()->use_ld_allocations && linker != nullptr;
   ForEachChunk(ProcessPlatformSpecificAllocationsCb, &arg);
 }
 

Modified: compiler-rt/trunk/lib/lsan/lsan_flags.inc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/lsan/lsan_flags.inc?rev=257789&r1=257788&r2=257789&view=diff
==============================================================================
--- compiler-rt/trunk/lib/lsan/lsan_flags.inc (original)
+++ compiler-rt/trunk/lib/lsan/lsan_flags.inc Thu Jan 14 13:16:05 2016
@@ -34,6 +34,10 @@ LSAN_FLAG(bool, use_tls, true,
           "Root set: include TLS and thread-specific storage")
 LSAN_FLAG(bool, use_root_regions, true,
           "Root set: include regions added via __lsan_register_root_region().")
+LSAN_FLAG(bool, use_ld_allocations, true,
+          "Root set: mark as reachable all allocations made from dynamic "
+          "linker. This was the old way to handle dynamic TLS, and will "
+          "be removed soon. Do not use this flag.")
 
 LSAN_FLAG(bool, use_unaligned, false, "Consider unaligned pointers valid.")
 LSAN_FLAG(bool, use_poisoned, false,

Modified: compiler-rt/trunk/test/lsan/TestCases/use_tls_dynamic.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/lsan/TestCases/use_tls_dynamic.cc?rev=257789&r1=257788&r2=257789&view=diff
==============================================================================
--- compiler-rt/trunk/test/lsan/TestCases/use_tls_dynamic.cc (original)
+++ compiler-rt/trunk/test/lsan/TestCases/use_tls_dynamic.cc Thu Jan 14 13:16:05 2016
@@ -1,5 +1,5 @@
 // Test that dynamically allocated TLS space is included in the root set.
-// RUN: LSAN_BASE="report_objects=1:use_stacks=0:use_registers=0"
+// RUN: LSAN_BASE="report_objects=1:use_stacks=0:use_registers=0:use_ld_allocations=0"
 // RUN: %clangxx %s -DBUILD_DSO -fPIC -shared -o %t-so.so
 // RUN: %clangxx_lsan %s -o %t
 // RUN: LSAN_OPTIONS=$LSAN_BASE:"use_tls=0" not %run %t 2>&1 | FileCheck %s