Make SyzyAsan support the allocation > 1GB

syzygy/agent/asan/block.h

Index: syzygy/agent/asan/block.h
diff --git a/syzygy/agent/asan/block.h b/syzygy/agent/asan/block.h
index a2f8e587c0d433e9a4485d5043cb9dd309af38e6..ab20132beb3a70aa926627de91879ceb87d1e1c7 100644
--- a/syzygy/agent/asan/block.h
+++ b/syzygy/agent/asan/block.h
@@ -112,7 +112,12 @@ static const uint8_t kBlockFloodFillByte = 0xFD;
 
 // The number of bits in the checksum field. This is parameterized so that
 // it can be referred to by the checksumming code.
-static const size_t kBlockHeaderChecksumBits = 14;
+static const size_t kBlockHeaderChecksumBits = 13;
+
+// The maximum allocation size that we can handle in SyzyAsan, this is
+// constrained by the number of bits used to store the block size in the block
+// header structure.
+static const uint32_t kBlockMaxAllocSize = static_cast<uint32_t>(1 << 31) - 1;

[chrisha, 2016/11/24 17:23:23]

Use a constexpr or a #define to store the value 31, and use that both here and
in the BlockState definition? Should help keep them in lockstep.

[Sébastien Marchand, 2016/11/25 02:38:21]

Done.

 
 // The state of an Asan block. These are in the order that reflects the typical
 // lifespan of an allocation.
@@ -157,7 +162,7 @@ struct BlockHeader {
     // (kShadowRatio / 2) - (body_size % (kShadowRatio / 2)).
     unsigned has_excess_trailer_padding : 1;
     // The size of the body of the allocation, in bytes.
-    unsigned body_size : 30;
+    unsigned body_size : 31;
   };
   // TODO(loskutov): replace pointers with something more compact.
   // The allocation stack of this block.