Move valid caller-pc checks out of platform-specific checks

[fjricci]

Summary

ProcessPlatformSpecificAllocations for linux leak sanitizer iterated over
memory chunks and ran two checks concurrently:

1. Ensured the pc was valid
2. Checked whether it was a linker allocation

All platforms will need the valid pc check, so it is moved out of the platform-
specific file. To prevent code and logic duplication, the linker allocation
check is moved as well, with the name of the linker supplied by the platform-specific
module. In cases where we don't need to check for linker allocations (ie Darwin),
this name will be a nullptr, and we'll only run the caller pc checks.

compiler-rt/trunk/lib/lsan/lsan_common.h

 void EnsureMainThreadIDIsCorrect();
 // If p points into a chunk that has been allocated to the user, returns its
 // user-visible address. Otherwise, returns 0.
 uptr PointsIntoChunk(void *p);
 // Returns address of user-visible chunk contained in this allocator chunk.
 uptr GetUserBegin(uptr chunk);
 // Helper for __lsan_ignore_object().
 IgnoreObjectResult IgnoreObjectLocked(const void *p);
+
+// Return the linker module, if valid for the platform.
+LoadedModule *GetLinker();
+
 // Wrapper for chunk metadata operations.
 class LsanMetadata {
  public:
   // Constructor accepts address of user-visible chunk.
   explicit LsanMetadata(uptr chunk);
   bool allocated() const;
   ChunkTag tag() const;
   void set_tag(ChunkTag value);

compiler-rt/trunk/lib/lsan/lsan_common.cc

static void CollectIgnoredCb(uptr chunk, void *arg) {
   LsanMetadata m(chunk);
   if (m.allocated() && m.tag() == kIgnored) {
     LOG_POINTERS("Ignored: chunk %p-%p of size %zu.\n",
                  chunk, chunk + m.requested_size(), m.requested_size());
     reinterpret_cast<Frontier *>(arg)->push_back(chunk);
   }
 }
 
+static uptr GetCallerPC(u32 stack_id, StackDepotReverseMap *map) {
+  CHECK(stack_id);
+  StackTrace stack = map->Get(stack_id);
+  // The top frame is our malloc/calloc/etc. The next frame is the caller.
+  if (stack.size >= 2)
+    return stack.trace[1];
+  return 0;
+}
+
+struct InvalidPCParam {
+  Frontier *frontier;
+  StackDepotReverseMap *stack_depot_reverse_map;
+  bool skip_linker_allocations;
+};
+
+// ForEachChunk callback. If the caller pc is invalid or is within the linker,
+// mark as reachable. Called by ProcessPlatformSpecificAllocations.
+static void MarkInvalidPCCb(uptr chunk, void *arg) {
+  CHECK(arg);
+  InvalidPCParam *param = reinterpret_cast<InvalidPCParam *>(arg);
+  chunk = GetUserBegin(chunk);
+  LsanMetadata m(chunk);
+  if (m.allocated() && m.tag() != kReachable && m.tag() != kIgnored) {
+    u32 stack_id = m.stack_trace_id();
+    uptr caller_pc = 0;
+    if (stack_id > 0)
+      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 || (param->skip_linker_allocations &&
+                           GetLinker()->containsAddress(caller_pc))) {
+      m.set_tag(kReachable);
+      param->frontier->push_back(chunk);
+    }
+  }
+}
+
+// On Linux, handles dynamically allocated TLS blocks by treating all chunks
+// allocated from ld-linux.so as reachable.
+// Dynamic TLS blocks contain the TLS variables of dynamically loaded modules.
+// They are allocated with a __libc_memalign() call in allocate_and_init()
+// (elf/dl-tls.c). Glibc won't tell us the address ranges occupied by those
+// blocks, but we can make sure they come from our own allocator by intercepting
+// __libc_memalign(). On top of that, there is no easy way to reach them. Their
+// addresses are stored in a dynamically allocated array (the DTV) which is
+// referenced from the static TLS. Unfortunately, we can't just rely on the DTV
+// being reachable from the static TLS, and the dynamic TLS being reachable from
+// the DTV. This is because the initial DTV is allocated before our interception
+// mechanism kicks in, and thus we don't recognize it as allocated memory. We
+// can't special-case it either, since we don't know its size.
+// Our solution is to include in the root set all allocations made from
+// ld-linux.so (which is where allocate_and_init() is implemented). This is
+// guaranteed to include all dynamic TLS blocks (and possibly other allocations
+// which we don't care about).
+// On all other platforms, this simply checks to ensure that the caller pc is
+// valid before reporting chunks as leaked.
+void ProcessPC(Frontier *frontier) {
+  StackDepotReverseMap stack_depot_reverse_map;
+  InvalidPCParam arg;
+  arg.frontier = frontier;
+  arg.stack_depot_reverse_map = &stack_depot_reverse_map;
+  arg.skip_linker_allocations =
+      flags()->use_tls && flags()->use_ld_allocations && GetLinker() != nullptr;
+  ForEachChunk(MarkInvalidPCCb, &arg);
+}
+
 // Sets the appropriate tag on each chunk.
 static void ClassifyAllChunks(SuspendedThreadsList const &suspended_threads) {
   // Holds the flood fill frontier.
   Frontier frontier(1);
 
   ForEachChunk(CollectIgnoredCb, &frontier);
   ProcessGlobalRegions(&frontier);
   ProcessThreads(suspended_threads, &frontier);
   ProcessRootRegions(&frontier);
   FloodFillTag(&frontier, kReachable);
 
+  CHECK_EQ(0, frontier.size());
+  ProcessPC(&frontier);
+
   // The check here is relatively expensive, so we do this in a separate flood
   // fill. That way we can skip the check for chunks that are reachable
   // otherwise.
   LOG_POINTERS("Processing platform-specific allocations.\n");
-  CHECK_EQ(0, frontier.size());
   ProcessPlatformSpecificAllocations(&frontier);
   FloodFillTag(&frontier, kReachable);
 
   // Iterate over leaked chunks and mark those that are reachable from other
   // leaked chunks.
   LOG_POINTERS("Scanning leaked chunks.\n");
   ForEachChunk(MarkIndirectlyLeakedCb, nullptr);
 }

compiler-rt/trunk/lib/lsan/lsan_common_linux.cc

 }
 
 // Scans global variables for heap pointers.
 void ProcessGlobalRegions(Frontier *frontier) {
   if (!flags()->use_globals) return;
   dl_iterate_phdr(ProcessGlobalRegionsCallback, frontier);
 }
 
-static uptr GetCallerPC(u32 stack_id, StackDepotReverseMap *map) {
-  CHECK(stack_id);
-  StackTrace stack = map->Get(stack_id);
-  // The top frame is our malloc/calloc/etc. The next frame is the caller.
-  if (stack.size >= 2)
-    return stack.trace[1];
-  return 0;
-}
+LoadedModule *GetLinker() { return linker; }
 
-struct ProcessPlatformAllocParam {
-  Frontier *frontier;
-  StackDepotReverseMap *stack_depot_reverse_map;
-  bool skip_linker_allocations;
-};
-
-// ForEachChunk callback. Identifies unreachable chunks which must be treated as
-// reachable. Marks them as reachable and adds them to the frontier.
-static void ProcessPlatformSpecificAllocationsCb(uptr chunk, void *arg) {
-  CHECK(arg);
-  ProcessPlatformAllocParam *param =
-      reinterpret_cast<ProcessPlatformAllocParam *>(arg);
-  chunk = GetUserBegin(chunk);
-  LsanMetadata m(chunk);
-  if (m.allocated() && m.tag() != kReachable && m.tag() != kIgnored) {
-    u32 stack_id = m.stack_trace_id();
-    uptr caller_pc = 0;
-    if (stack_id > 0)
-      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 || (param->skip_linker_allocations &&
-                           linker->containsAddress(caller_pc))) {
-      m.set_tag(kReachable);
-      param->frontier->push_back(chunk);
-    }
-  }
-}
-
-// Handles dynamically allocated TLS blocks by treating all chunks allocated
-// from ld-linux.so as reachable.
-// Dynamic TLS blocks contain the TLS variables of dynamically loaded modules.
-// They are allocated with a __libc_memalign() call in allocate_and_init()
-// (elf/dl-tls.c). Glibc won't tell us the address ranges occupied by those
-// blocks, but we can make sure they come from our own allocator by intercepting
-// __libc_memalign(). On top of that, there is no easy way to reach them. Their
-// addresses are stored in a dynamically allocated array (the DTV) which is
-// referenced from the static TLS. Unfortunately, we can't just rely on the DTV
-// being reachable from the static TLS, and the dynamic TLS being reachable from
-// the DTV. This is because the initial DTV is allocated before our interception
-// mechanism kicks in, and thus we don't recognize it as allocated memory. We
-// can't special-case it either, since we don't know its size.
-// Our solution is to include in the root set all allocations made from
-// ld-linux.so (which is where allocate_and_init() is implemented). This is
-// guaranteed to include all dynamic TLS blocks (and possibly other allocations
-// which we don't care about).
-void ProcessPlatformSpecificAllocations(Frontier *frontier) {
-  StackDepotReverseMap 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);
-}
+void ProcessPlatformSpecificAllocations(Frontier *frontier) {}
 
 struct DoStopTheWorldParam {
   StopTheWorldCallback callback;
   void *argument;
 };
 
 static int DoStopTheWorldCallback(struct dl_phdr_info *info, size_t size,
                                   void *data) {

compiler-rt/trunk/lib/lsan/lsan_common_mac.cc

u32 GetCurrentThread() {
   CHECK(data);
   return data->current_thread_id;
 }
 
 void SetCurrentThread(u32 tid) { get_tls_val(true)->current_thread_id = tid; }
 
 AllocatorCache *GetAllocatorCache() { return &get_tls_val(true)->cache; }
 
+LoadedModule *GetLinker() { return nullptr; }
+
 // Required on Linux for initialization of TLS behavior, but should not be
 // required on Darwin.
 void InitializePlatformSpecificModules() {
   if (flags()->use_tls) {
     Report("use_tls=1 is not supported on Darwin.\n");
     Die();
   }
 }