[PowerPC][msan] Update msan to handle changed memory layouts in 47 bit VMA kernels

[seurer]

Summary

[PowerPC][msan] Update msan to handle changed memory layouts in newer kernels

In more recent Linux kernels (including those with 47 bit VMAs) the layout of
virtual memory for powerpc64 changed causing the memory sanitizer to not
work properly. This patch adjusts the memory ranges in the tables for the
memory sanitizer to work on the newer kernels while continuing to work on the
older ones as well.

Tested on several 4.x and 3.x kernel releases.

[eugenis]

@alekseyshl FYI

[seurer]

Code checked in as r317802.

lib/msan/msan.h

const MappingDesc kMemoryLayout[] = {
     {0x0FFAF00000000ULL, 0x0FFB000000000ULL, MappingDesc::ORIGIN, "origin-15"},
     {0x0FFB000000000ULL, 0x0FFFF00000000ULL, MappingDesc::INVALID, "invalid"},
     {0x0FFFF00000000ULL, 0x1000000000000ULL, MappingDesc::APP, "app-15"},
 };
 # define MEM_TO_SHADOW(mem) ((uptr)mem ^ 0x6000000000ULL)
 # define SHADOW_TO_ORIGIN(shadow) (((uptr)(shadow)) + 0x1000000000ULL)
 
 #elif SANITIZER_LINUX && SANITIZER_PPC64
-
 const MappingDesc kMemoryLayout[] = {
-    {0x000000000000ULL, 0x000100000000ULL, MappingDesc::APP, "low memory"},
-    {0x000100000000ULL, 0x080000000000ULL, MappingDesc::INVALID, "invalid"},
-    {0x080000000000ULL, 0x180100000000ULL, MappingDesc::SHADOW, "shadow"},
-    {0x180100000000ULL, 0x1C0000000000ULL, MappingDesc::INVALID, "invalid"},
-    {0x1C0000000000ULL, 0x2C0100000000ULL, MappingDesc::ORIGIN, "origin"},
-    {0x2C0100000000ULL, 0x300000000000ULL, MappingDesc::INVALID, "invalid"},
-    {0x300000000000ULL, 0x400000000000ULL, MappingDesc::APP, "high memory"}};
-
+    {0x000000000000ULL, 0x000200000000ULL, MappingDesc::APP, "low memory"},
+    {0x000200000000ULL, 0x080000000000ULL, MappingDesc::INVALID, "invalid"},
+    {0x080000000000ULL, 0x180200000000ULL, MappingDesc::SHADOW, "shadow"},
+    {0x180200000000ULL, 0x1C0000000000ULL, MappingDesc::INVALID, "invalid"},
+    {0x1C0000000000ULL, 0x2C0200000000ULL, MappingDesc::ORIGIN, "origin"},
+    {0x2C0200000000ULL, 0x300000000000ULL, MappingDesc::INVALID, "invalid"},
+    {0x300000000000ULL, 0x800000000000ULL, MappingDesc::APP, "high memory"}};
+
+// Various kernels use different low end ranges but we can combine them into one
+// big range. They also use different high end ranges but we can map them all to
+// one range.
 // Maps low and high app ranges to contiguous space with zero base:
-//   Low:  0000 0000 0000 - 0000 ffff ffff  ->  1000 0000 0000 - 1000 ffff ffff
+//   Low:  0000 0000 0000 - 0001 ffff ffff  ->  1000 0000 0000 - 1001 ffff ffff
 //   High: 3000 0000 0000 - 3fff ffff ffff  ->  0000 0000 0000 - 0fff ffff ffff
+//   High: 4000 0000 0000 - 4fff ffff ffff  ->  0000 0000 0000 - 0fff ffff ffff
+//   High: 7000 0000 0000 - 7fff ffff ffff  ->  0000 0000 0000 - 0fff ffff ffff
 #define LINEARIZE_MEM(mem) \
-  (((uptr)(mem) & ~0x200000000000ULL) ^ 0x100000000000ULL)
+  (((uptr)(mem) & ~0xE00000000000ULL) ^ 0x100000000000ULL)
 #define MEM_TO_SHADOW(mem) (LINEARIZE_MEM((mem)) + 0x080000000000ULL)
 #define SHADOW_TO_ORIGIN(shadow) (((uptr)(shadow)) + 0x140000000000ULL)
 
 #elif SANITIZER_FREEBSD && SANITIZER_WORDSIZE == 64
 
 // Low memory: main binary, MAP_32BIT mappings and modules
 // High memory: heap, modules and main thread stack
 const MappingDesc kMemoryLayout[] = {