Register NetBSD/i386 in asan_mapping.h

[krytarowski]

Summary

Introduce kNetBSD_ShadowOffset32 and document
NetBSD/i386 (hosted on amd64 kernel) process virtual
address space ranges.

Sponsored by <The NetBSD Foundation>

lib/asan/asan_mapping.h

 //
 // Shadow mapping on NetBSD/x86-64 with SHADOW_OFFSET == 0x400000000000:
 // || `[0x4feffffffe01, 0x7f7ffffff000]` || HighMem    ||
 // || `[0x49fdffffffc0, 0x4feffffffe00]` || HighShadow ||
 // || `[0x480000000000, 0x49fdffffffbf]` || ShadowGap  ||
 // || `[0x400000000000, 0x47ffffffffff]` || LowShadow  ||
 // || `[0x000000000000, 0x3fffffffffff]` || LowMem     ||
 //
+// Shadow mapping on NerBSD/i386 with SHADOW_OFFSET == 0x40000000:
+// || `[0x60000000, 0xfffff000]` || HighMem    ||
+// || `[0x4c000000, 0x5fffffff]` || HighShadow ||
+// || `[0x48000000, 0x4bffffff]` || ShadowGap  ||
+// || `[0x40000000, 0x47ffffff]` || LowShadow  ||
+// || `[0x00000000, 0x3fffffff]` || LowMem     ||
+//
 // Default Windows/i386 mapping:
 // (the exact location of HighShadow/HighMem may vary depending
 //  on WoW64, /LARGEADDRESSAWARE, etc).
 // || `[0x50000000, 0xffffffff]` || HighMem    ||
 // || `[0x3a000000, 0x4fffffff]` || HighShadow ||
 // || `[0x36000000, 0x39ffffff]` || ShadowGap  ||
 // || `[0x30000000, 0x35ffffff]` || LowShadow  ||
 // || `[0x00000000, 0x2fffffff]` || LowMem     ||

 static const u64 kIosSimShadowOffset64 = kDefaultShadowOffset64;
 static const u64 kAArch64_ShadowOffset64 = 1ULL << 36;
 static const u64 kMIPS32_ShadowOffset32 = 0x0aaa0000;
 static const u64 kMIPS64_ShadowOffset64 = 1ULL << 37;
 static const u64 kPPC64_ShadowOffset64 = 1ULL << 44;
 static const u64 kSystemZ_ShadowOffset64 = 1ULL << 52;
 static const u64 kFreeBSD_ShadowOffset32 = 1ULL << 30;  // 0x40000000
 static const u64 kFreeBSD_ShadowOffset64 = 1ULL << 46;  // 0x400000000000
+static const u64 kNetBSD_ShadowOffset32 = 1ULL << 30;  // 0x40000000
 static const u64 kNetBSD_ShadowOffset64 = 1ULL << 46;  // 0x400000000000
 static const u64 kWindowsShadowOffset32 = 3ULL << 28;  // 0x30000000
 
 #define SHADOW_SCALE kDefaultShadowScale
 
 #if SANITIZER_FUCHSIA
 #  define SHADOW_OFFSET (0)
 #elif SANITIZER_WORDSIZE == 32
 #  if SANITIZER_ANDROID
 #    define SHADOW_OFFSET __asan_shadow_memory_dynamic_address
 #  elif defined(__mips__)
 #    define SHADOW_OFFSET kMIPS32_ShadowOffset32
 #  elif SANITIZER_FREEBSD
 #    define SHADOW_OFFSET kFreeBSD_ShadowOffset32
+#  elif SANITIZER_NETBSD
+#    define SHADOW_OFFSET kNetBSD_ShadowOffset32
 #  elif SANITIZER_WINDOWS
 #    define SHADOW_OFFSET kWindowsShadowOffset32
 #  elif SANITIZER_IOS
 #    if SANITIZER_IOSSIM
 #      define SHADOW_OFFSET kIosSimShadowOffset32
 #    else
 #      define SHADOW_OFFSET kIosShadowOffset32
 #    endif