[sanitizer_common] Introduce SANITIZER_MMAP_BEGIN macro (#147645)

To prepare for other platforms, such as 64-bit AIX, that have a non-zero
mmap beginning address.

---------

Co-authored-by: David Justo <david.justo.1996@gmail.com>

Author: jakeegan

compiler-rt/lib/asan/asan_allocator.h

@@ -239,7 +239,7 @@ using PrimaryAllocator = PrimaryAllocatorASVT<LocalAddressSpaceView>;
 typedef CompactSizeClassMap SizeClassMap;
 template <typename AddressSpaceViewTy>
 struct AP32 {
-  static const uptr kSpaceBeg = 0;
+  static const uptr kSpaceBeg = SANITIZER_MMAP_BEGIN;
   static const u64 kSpaceSize = SANITIZER_MMAP_RANGE_SIZE;
   static const uptr kMetadataSize = 0;
   typedef __asan::SizeClassMap SizeClassMap;

compiler-rt/lib/lsan/lsan_allocator.h

@@ -53,7 +53,7 @@ struct ChunkMetadata {
 #if !SANITIZER_CAN_USE_ALLOCATOR64
 template <typename AddressSpaceViewTy>
 struct AP32 {
-  static const uptr kSpaceBeg = 0;
+  static const uptr kSpaceBeg = SANITIZER_MMAP_BEGIN;
   static const u64 kSpaceSize = SANITIZER_MMAP_RANGE_SIZE;
   static const uptr kMetadataSize = sizeof(ChunkMetadata);
   typedef __sanitizer::CompactSizeClassMap SizeClassMap;

compiler-rt/lib/msan/msan_allocator.cpp

@@ -56,7 +56,7 @@ struct MsanMapUnmapCallback {
 const uptr kMaxAllowedMallocSize = 2UL << 30;
 
 struct AP32 {
-  static const uptr kSpaceBeg = 0;
+  static const uptr kSpaceBeg = SANITIZER_MMAP_BEGIN;
   static const u64 kSpaceSize = SANITIZER_MMAP_RANGE_SIZE;
   static const uptr kMetadataSize = sizeof(Metadata);
   using SizeClassMap = __sanitizer::CompactSizeClassMap;

compiler-rt/lib/sanitizer_common/sanitizer_allocator_internal.h

@@ -23,7 +23,7 @@ namespace __sanitizer {
 typedef CompactSizeClassMap InternalSizeClassMap;
 
 struct AP32 {
-  static const uptr kSpaceBeg = 0;
+  static const uptr kSpaceBeg = SANITIZER_MMAP_BEGIN;
   static const u64 kSpaceSize = SANITIZER_MMAP_RANGE_SIZE;
   static const uptr kMetadataSize = 0;
   typedef InternalSizeClassMap SizeClassMap;

compiler-rt/lib/sanitizer_common/sanitizer_platform.h

@@ -318,6 +318,9 @@
 #  endif
 #endif
 
+// The first address that can be returned by mmap.
+#define SANITIZER_MMAP_BEGIN 0
+
 // The range of addresses which can be returned my mmap.
 // FIXME: this value should be different on different platforms.  Larger values
 // will still work but will consume more memory for TwoLevelByteMap.

compiler-rt/lib/tsan/rtl/tsan_rtl.h

@@ -62,7 +62,7 @@ struct MapUnmapCallback;
       defined(__powerpc__) || SANITIZER_RISCV64
 
 struct AP32 {
-  static const uptr kSpaceBeg = 0;
+  static const uptr kSpaceBeg = SANITIZER_MMAP_BEGIN;
   static const u64 kSpaceSize = SANITIZER_MMAP_RANGE_SIZE;
   static const uptr kMetadataSize = 0;
   typedef __sanitizer::CompactSizeClassMap SizeClassMap;