[compiler-rt] r346420 - Introduce `sanitizer_malloc_introspect_t` for Darwin which is a sub-class of Darwin's `malloc_introspection_t` and use it when setting up the malloc zone.

[Dan Liew via llvm-commits]

Author: delcypher
Date: Thu Nov  8 09:50:34 2018
New Revision: 346420

URL: http://llvm.org/viewvc/llvm-project?rev=346420&view=rev
Log:
Introduce `sanitizer_malloc_introspect_t` for Darwin which is a sub-class of Darwin's `malloc_introspection_t` and use it when setting up the malloc zone.

Summary:
Currently `sanitizer_malloc_introspection_t` just adds a version field
which is used to version the allocator ABI. The current allocator ABI
version is returned by the new `GetMallocZoneAllocatorEnumerationVersion()` function.

The motivation behind this change is to allow external processes to
determine the allocator ABI of a sanitized process.

rdar://problem/45284065

Reviewers: kubamracek, george.karpenkov, vitalybuka

Subscribers: #sanitizers, llvm-commits

Differential Revision: https://reviews.llvm.org/D54045

Modified:
    compiler-rt/trunk/lib/sanitizer_common/sanitizer_malloc_mac.inc

Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_malloc_mac.inc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_malloc_mac.inc?rev=346420&r1=346419&r2=346420&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_malloc_mac.inc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_malloc_mac.inc Thu Nov  8 09:50:34 2018
@@ -30,9 +30,27 @@
 // https://github.com/gperftools/gperftools.
 
 namespace __sanitizer {
+
 extern malloc_zone_t sanitizer_zone;
+
+struct sanitizer_malloc_introspection_t : public malloc_introspection_t {
+  // IMPORTANT: Do not change the order, alignment, or types of these fields to
+  // maintain binary compatibility. You should only add fields to this struct.
+
+  // Used to track changes to the allocator that will affect
+  // zone enumeration.
+  u64 allocator_enumeration_version;
+};
+
+u64 GetMallocZoneAllocatorEnumerationVersion() {
+  // This represents the current allocator ABI version.
+  // This field should be incremented every time the Allocator
+  // ABI changes in a way that breaks allocator enumeration.
+  return 0;
 }
 
+}  // namespace __sanitizer
+
 INTERCEPTOR(malloc_zone_t *, malloc_create_zone,
                              vm_size_t start_size, unsigned zone_flags) {
   COMMON_MALLOC_ENTER();
@@ -303,7 +321,7 @@ boolean_t mi_zone_locked(malloc_zone_t *
 namespace COMMON_MALLOC_NAMESPACE {
 
 void InitMallocZoneFields() {
-  static malloc_introspection_t sanitizer_zone_introspection;
+  static sanitizer_malloc_introspection_t sanitizer_zone_introspection;
   // Ok to use internal_memset, these places are not performance-critical.
   internal_memset(&sanitizer_zone_introspection, 0,
                   sizeof(sanitizer_zone_introspection));
@@ -318,6 +336,10 @@ void InitMallocZoneFields() {
   sanitizer_zone_introspection.statistics = &mi_statistics;
   sanitizer_zone_introspection.zone_locked = &mi_zone_locked;
 
+  // Set current allocator enumeration version.
+  sanitizer_zone_introspection.allocator_enumeration_version =
+      GetMallocZoneAllocatorEnumerationVersion();
+
   internal_memset(&sanitizer_zone, 0, sizeof(malloc_zone_t));
 
   // Use version 6 for OSX >= 10.6.