Index: lib/msan/msan.h
===================================================================
--- lib/msan/msan.h
+++ lib/msan/msan.h
@@ -25,22 +25,91 @@
 # define MSAN_REPLACE_OPERATORS_NEW_AND_DELETE 1
 #endif
 
-#if defined(__mips64)
-#define MEM_TO_SHADOW(mem)       (((uptr)mem) & ~0x4000000000ULL)
-#define SHADOW_TO_ORIGIN(shadow) (((uptr)shadow) + 0x2000000000ULL)
-#define MEM_TO_ORIGIN(mem)       (SHADOW_TO_ORIGIN(MEM_TO_SHADOW(mem)))
-#define MEM_IS_APP(mem)          ((uptr)mem >= 0xe000000000ULL)
-#define MEM_IS_SHADOW(mem) \
-  ((uptr)mem >= 0xa000000000ULL && (uptr)mem <= 0xc000000000ULL)
-#elif defined(__x86_64__)
-#define MEM_TO_SHADOW(mem)       (((uptr)mem) & ~0x400000000000ULL)
-#define SHADOW_TO_ORIGIN(shadow) (((uptr)shadow) + 0x200000000000ULL)
-#define MEM_TO_ORIGIN(mem)       (SHADOW_TO_ORIGIN(MEM_TO_SHADOW(mem)))
-#define MEM_IS_APP(mem)          ((uptr)mem >= 0x600000000000ULL)
-#define MEM_IS_SHADOW(mem) \
-  ((uptr)mem >= 0x200000000000ULL && (uptr)mem <= 0x400000000000ULL)
+/*
+C/C++ on FreeBSD
+0000 0000 0000 - 00ff ffff ffff: Low memory: main binary, MAP_32BIT mappings and modules
+0100 0000 0000 - 0fff ffff ffff: Bad1
+1000 0000 0000 - 30ff ffff ffff: Shadow
+3100 0000 0000 - 37ff ffff ffff: Bad2
+3800 0000 0000 - 58ff ffff ffff: Origins
+5900 0000 0000 - 5fff ffff ffff: Bad3
+6000 0000 0000 - 7fff ffff ffff: High memory: traces, heap, modules and main thread stack
+
+C/C++ on Linux/PIE
+0000 0000 0000 - 1fff ffff ffff: Bad1
+2000 0000 0000 - 3fff ffff ffff: Shadow
+4000 0000 0000 - 5fff ffff ffff: Origins
+6000 0000 0000 - 7fff ffff ffff: Main memory
+
+C/C++ on Mips
+0000 0000 0000 - 009f ffff ffff: Bad1
+00a0 0000 0000 - 00bf ffff ffff: Shadow
+00c0 0000 0000 - 00df ffff ffff: Origins
+00e0 0000 0000 - 00ff ffff ffff: Main memory
+*/
+
+#if SANITIZER_LINUX && defined(__mips64)
+const uptr kLowMemBeg   = 0;
+const uptr kLowMemSize  = 0;
+const uptr kHighMemBeg  = 0x00e000000000;
+const uptr kHighMemSize = 0x002000000000;
+const uptr kShadowBeg   = 0x00a000000000;
+const uptr kShadowSize  = 0x002000000000;
+const uptr kOriginsBeg  = 0x00c000000000;
+# define MEM_TO_SHADOW(mem) (((uptr)(mem)) & ~0x4000000000ULL)
+#elif SANITIZER_FREEBSD && SANITIZER_WORDSIZE == 64
+const uptr kLowMemBeg   = 0x000000000000;
+const uptr kLowMemsize  = 0x010000000000;
+const uptr kHighMemBeg  = 0x600000000000;
+const uptr kHighMemsize = 0x200000000000;
+const uptr kShadowBeg   = 0x100000000000;
+const uptr kShadowSize  = 0x110000000000;
+const uptr kOriginsBeg  = 0x380000000000;
+// Maps low and high app ranges to contiguous space with zero base:
+//   Low:  0000 0000 0000 - 00ff ffff ffff  ->  2000 0000 0000 - 20ff ffff ffff
+//   High: 6000 0000 0000 - 7fff ffff ffff  ->  0000 0000 0000 - 1fff ffff ffff
+# define LINEARIZE_MEM(mem) \
+    (((uptr)(mem) & ~0xc00000000000ULL) ^ 0x200000000000ULL)
+# define MEM_TO_SHADOW(mem) (LINEARIZE_MEM((mem)) + 0x100000000000ULL)
+#elif SANITIZER_LINUX && SANITIZER_WORDSIZE == 64
+const uptr kLowMemBeg   = 0;
+const uptr kLowMemSize  = 0;
+const uptr kHighMemBeg  = 0x600000000000;
+const uptr kHighMemSize = 0x200000000000;
+const uptr kShadowBeg   = 0x200000000000;
+const uptr kShadowSize  = 0x200000000000;
+const uptr kOriginsBeg  = 0x400000000000;
+# define MEM_TO_SHADOW(mem) (((uptr)(mem)) & ~0x400000000000ULL)
+#else
+#error "Unsupported platform"
 #endif
 
+const uptr kBad1Beg  = kLowMemBeg + kLowMemSize;
+const uptr kBad1Size = kShadowBeg - kBad1Beg;
+
+const uptr kBad2Beg  = kShadowBeg + kShadowSize;
+const uptr kBad2Size = kOriginsBeg - kBad2Beg;
+
+const uptr kOriginsSize = kShadowSize;
+
+const uptr kBad3Beg  = kOriginsBeg + kOriginsSize;
+const uptr kBad3Size = kHighMemBeg - kBad3Beg;
+
+#define SHADOW_TO_ORIGIN(shadow) \
+  (((uptr)(shadow)) + (kOriginsBeg - kShadowBeg))
+
+#define MEM_TO_ORIGIN(mem) (SHADOW_TO_ORIGIN(MEM_TO_SHADOW((mem))))
+
+#define MEM_IS_APP(mem) \
+  ((kLowMemSize > 0 && (uptr)(mem) < kLowMemSize) || \
+    (uptr)(mem) >= kHighMemBeg)
+
+#define MEM_IS_SHADOW(mem) \
+  ((uptr)(mem) >= kShadowBeg && (uptr)(mem) < kShadowBeg + kShadowSize)
+
+#define MEM_IS_ORIGIN(mem) \
+  ((uptr)(mem) >= kOriginsBeg && (uptr)(mem) < kOriginsBeg + kOriginsSize)
+
 // These constants must be kept in sync with the ones in MemorySanitizer.cc.
 const int kMsanParamTlsSize = 800;
 const int kMsanRetvalTlsSize = 800;
@@ -51,7 +120,8 @@
 extern int msan_report_count;
 
 bool ProtectRange(uptr beg, uptr end);
-bool InitShadow(bool prot1, bool prot2, bool map_shadow, bool init_origins);
+bool InitShadow(bool prot1, bool prot2, bool prot3,
+                bool map_shadow, bool init_origins);
 char *GetProcSelfMaps();
 void InitializeInterceptors();
 
Index: lib/msan/msan.cc
===================================================================
--- lib/msan/msan.cc
+++ lib/msan/msan.cc
@@ -383,7 +383,7 @@
   __msan_clear_on_return();
   if (__msan_get_track_origins())
     VPrintf(1, "msan_track_origins\n");
-  if (!InitShadow(/* prot1 */ true, /* prot2 */ true,
+  if (!InitShadow(/* prot1 */ true, /* prot2 */ true, /* prot3 */ true,
                   /* map_shadow */ true, __msan_get_track_origins())) {
     Printf("FATAL: MemorySanitizer can not mmap the shadow memory.\n");
     Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n");
Index: lib/msan/msan_interceptors.cc
===================================================================
--- lib/msan/msan_interceptors.cc
+++ lib/msan/msan_interceptors.cc
@@ -1320,7 +1320,7 @@
   unsigned char *s = (unsigned char *)MEM_TO_SHADOW(addr);
   for (uptr i = 0; i < size; ++i)
     if (s[i])
-      return *(u32 *)SHADOW_TO_ORIGIN((s + i) & ~3UL);
+      return *(u32 *)SHADOW_TO_ORIGIN(((uptr)s + i) & ~3UL);
   return 0;
 }
 
Index: lib/msan/msan_linux.cc
===================================================================
--- lib/msan/msan_linux.cc
+++ lib/msan/msan_linux.cc
@@ -9,11 +9,11 @@
 //
 // This file is a part of MemorySanitizer.
 //
-// Linux-specific code.
+// Linux- and FreeBSD-specific code.
 //===----------------------------------------------------------------------===//
 
 #include "sanitizer_common/sanitizer_platform.h"
-#if SANITIZER_LINUX
+#if SANITIZER_FREEBSD || SANITIZER_LINUX
 
 #include "msan.h"
 #include "msan_thread.h"
@@ -35,55 +35,83 @@
 
 namespace __msan {
 
-#if defined(__mips64)
-static const uptr kMemBeg     = 0xe000000000;
-static const uptr kMemEnd     = 0xffffffffff;
-#elif defined(__x86_64__)
-static const uptr kMemBeg     = 0x600000000000;
-static const uptr kMemEnd     = 0x7fffffffffff;
-#endif
-
-static const uptr kShadowBeg  = MEM_TO_SHADOW(kMemBeg);
-static const uptr kShadowEnd  = MEM_TO_SHADOW(kMemEnd);
-static const uptr kBad1Beg    = 0;
-static const uptr kBad1End    = kShadowBeg - 1;
-static const uptr kBad2Beg    = kShadowEnd + 1;
-static const uptr kBad2End    = kMemBeg - 1;
-static const uptr kOriginsBeg = kBad2Beg;
-static const uptr kOriginsEnd = kBad2End;
+static void ReportMapRange(const char *descr, uptr beg, uptr size) {
+  if (size > 0)
+    VPrintf(1, "%s : %p - %p\n", descr, beg, beg + size - 1);
+}
+
+static bool TakeMapRange(uptr beg, uptr size, bool protect) {
+  if (size > 0) {
+    uptr end = beg + size - 1;
+    if (!MemoryRangeIsAvailable(beg, end)) {
+      Printf("FATAL: Memory range %p - %p is not available.\n", beg, end);
+      return false;
+    }
+    if (protect && !Mprotect(beg, size)) {
+      Printf("FATAL: Cannot protect memory range %p - %p.\n", beg, end);
+      return false;
+    }
+  }
+  return true;
+}
+
+bool InitShadow(bool prot1, bool prot2, bool prot3,
+                bool map_shadow, bool init_origins) {
+  // Let user know mapping parameters first.
+  VPrintf(1, "__msan_init %p\n", &__msan_init);
+  ReportMapRange("Low Memory ", kLowMemBeg, kLowMemSize);
+  ReportMapRange("Bad1       ", kBad1Beg, kBad1Size);
+  ReportMapRange("Shadow     ", kShadowBeg, kShadowSize);
+  ReportMapRange("Bad2       ", kBad2Beg, kBad2Size);
+  ReportMapRange("Origins    ", kOriginsBeg, kOriginsSize);
+  ReportMapRange("Bad3       ", kBad3Beg, kBad3Size);
+  ReportMapRange("High Memory", kHighMemBeg, kHighMemSize);
+
+  // Check mapping sanity (the invariant).
+  CHECK_EQ(kLowMemBeg, 0);
+  CHECK_EQ(kBad1Beg, kLowMemBeg + kLowMemSize);
+  CHECK_EQ(kShadowBeg, kBad1Beg + kBad1Size);
+  CHECK_GT(kShadowSize, 0);
+  CHECK_GE(kShadowSize, kLowMemSize + kHighMemSize);
+  CHECK_EQ(kBad2Beg, kShadowBeg + kShadowSize);
+  CHECK_EQ(kOriginsBeg, kBad2Beg + kBad2Size);
+  CHECK_EQ(kOriginsSize, kShadowSize);
+  CHECK_EQ(kBad3Beg, kOriginsBeg + kOriginsSize);
+  CHECK_EQ(kHighMemBeg, kBad3Beg + kBad3Size);
+  CHECK_GT(kHighMemSize, 0);
+  CHECK_GE(kHighMemBeg + kHighMemSize, kHighMemBeg);  // Tests for no overflow.
+
+  if (kLowMemSize > 0) {
+    CHECK(MEM_IS_SHADOW(MEM_TO_SHADOW(kLowMemBeg)));
+    CHECK(MEM_IS_SHADOW(MEM_TO_SHADOW(kLowMemBeg + kLowMemSize - 1)));
+    CHECK(MEM_IS_ORIGIN(MEM_TO_ORIGIN(kLowMemBeg)));
+    CHECK(MEM_IS_ORIGIN(MEM_TO_ORIGIN(kLowMemBeg + kLowMemSize - 1)));
+  }
+  CHECK(MEM_IS_SHADOW(MEM_TO_SHADOW(kHighMemBeg)));
+  CHECK(MEM_IS_SHADOW(MEM_TO_SHADOW(kHighMemBeg + kHighMemSize - 1)));
+  CHECK(MEM_IS_ORIGIN(MEM_TO_ORIGIN(kHighMemBeg)));
+  CHECK(MEM_IS_ORIGIN(MEM_TO_ORIGIN(kHighMemBeg + kHighMemSize - 1)));
 
-bool InitShadow(bool prot1, bool prot2, bool map_shadow, bool init_origins) {
-  if ((uptr) & InitShadow < kMemBeg) {
+  if (kLowMemSize == 0 && (uptr)&__msan_init < kHighMemBeg) {
     Printf("FATAL: Code below application range: %p < %p. Non-PIE build?\n",
-           &InitShadow, (void *)kMemBeg);
+           (uptr)&__msan_init, (void*)kHighMemBeg);
     return false;
   }
 
-  VPrintf(1, "__msan_init %p\n", &__msan_init);
-  VPrintf(1, "Memory   : %p %p\n", kMemBeg, kMemEnd);
-  VPrintf(1, "Bad2     : %p %p\n", kBad2Beg, kBad2End);
-  VPrintf(1, "Origins  : %p %p\n", kOriginsBeg, kOriginsEnd);
-  VPrintf(1, "Shadow   : %p %p\n", kShadowBeg, kShadowEnd);
-  VPrintf(1, "Bad1     : %p %p\n", kBad1Beg, kBad1End);
-
-  if (!MemoryRangeIsAvailable(kShadowBeg,
-                              init_origins ? kOriginsEnd : kShadowEnd) ||
-      (prot1 && !MemoryRangeIsAvailable(kBad1Beg, kBad1End)) ||
-      (prot2 && !MemoryRangeIsAvailable(kBad2Beg, kBad2End))) {
-    Printf("FATAL: Shadow memory range is not available.\n");
+  if (!TakeMapRange(kShadowBeg, kShadowSize, false) ||
+      (init_origins && !TakeMapRange(kOriginsBeg, kOriginsSize, false)) ||
+      (prot1 && !TakeMapRange(kBad1Beg, kBad1Size, true)) ||
+      (prot2 && !TakeMapRange(kBad2Beg, kBad2Size, true)) ||
+      (prot3 && !TakeMapRange(kBad3Beg, kBad3Size, true))) {
     return false;
   }
 
-  if (prot1 && !Mprotect(kBad1Beg, kBad1End - kBad1Beg))
-    return false;
-  if (prot2 && !Mprotect(kBad2Beg, kBad2End - kBad2Beg))
-    return false;
   if (map_shadow) {
-    void *shadow = MmapFixedNoReserve(kShadowBeg, kShadowEnd - kShadowBeg);
+    void *shadow = MmapFixedNoReserve(kShadowBeg, kShadowSize);
     if (shadow != (void*)kShadowBeg) return false;
   }
   if (init_origins) {
-    void *origins = MmapFixedNoReserve(kOriginsBeg, kOriginsEnd - kOriginsBeg);
+    void *origins = MmapFixedNoReserve(kOriginsBeg, kOriginsSize);
     if (origins != (void*)kOriginsBeg) return false;
   }
   return true;
@@ -140,4 +168,4 @@
 
 }  // namespace __msan
 
-#endif  // __linux__
+#endif  // SANITIZER_FREEBSD || SANITIZER_LINUX