[PATCH] [ASan] Use less shadow on Win 32-bit

[Timur Iskhodzhanov]

Hi kcc,

http://llvm-reviews.chandlerc.com/D1139

Files:
  lib/asan/asan_rtl.cc
  lib/sanitizer_common/sanitizer_common.h
  lib/sanitizer_common/sanitizer_win.cc
  lib/sanitizer_common/sanitizer_posix.cc

Index: lib/asan/asan_rtl.cc
===================================================================
--- lib/asan/asan_rtl.cc
+++ lib/asan/asan_rtl.cc
@@ -328,22 +328,13 @@
 
 static void InitializeHighMemEnd() {
 #if !ASAN_FIXED_MAPPING
-#if SANITIZER_WORDSIZE == 64
-# if defined(__powerpc64__)
-  // FIXME:
-  // On PowerPC64 we have two different address space layouts: 44- and 46-bit.
-  // We somehow need to figure our which one we are using now and choose
-  // one of 0x00000fffffffffffUL and 0x00003fffffffffffUL.
-  // Note that with 'ulimit -s unlimited' the stack is moved away from the top
-  // of the address space, so simply checking the stack address is not enough.
-  kHighMemEnd = (1ULL << 44) - 1;  // 0x00000fffffffffffUL
-# else
-  kHighMemEnd = (1ULL << 47) - 1;  // 0x00007fffffffffffUL;
-# endif
-#else  // SANITIZER_WORDSIZE == 32
-  kHighMemEnd = (1ULL << 32) - 1;  // 0xffffffff;
-#endif  // SANITIZER_WORDSIZE
+  kHighMemEnd = GetMaxVirtualAddress();
+  // Make sure everything is properly aligned:
+  kHighMemEnd = kHighMemEnd | (GetPageSizeCached() - 1);
+  while (kHighMemBeg % GetPageSizeCached())
+    kHighMemEnd += GetPageSizeCached();
 #endif  // !ASAN_FIXED_MAPPING
+  CHECK_EQ((kHighMemBeg % GetPageSizeCached()), 0);
 }
 
 static void ProtectGap(uptr a, uptr size) {
@@ -486,10 +477,10 @@
   ReplaceOperatorsNewAndDelete();
 
   uptr shadow_start = kLowShadowBeg;
-  if (kLowShadowBeg) shadow_start -= GetMmapGranularity();
-  uptr shadow_end = kHighShadowEnd;
+  if (kLowShadowBeg)
+    shadow_start -= GetMmapGranularity();
   bool full_shadow_is_available =
-      MemoryRangeIsAvailable(shadow_start, shadow_end);
+      MemoryRangeIsAvailable(shadow_start, kHighShadowEnd);
 
 #if SANITIZER_LINUX && defined(__x86_64__) && !ASAN_FIXED_MAPPING
   if (!full_shadow_is_available) {
@@ -515,7 +506,7 @@
     ProtectGap(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
   } else if (kMidMemBeg &&
       MemoryRangeIsAvailable(shadow_start, kMidMemBeg - 1) &&
-      MemoryRangeIsAvailable(kMidMemEnd + 1, shadow_end)) {
+      MemoryRangeIsAvailable(kMidMemEnd + 1, kHighShadowEnd)) {
     CHECK(kLowShadowBeg != kLowShadowEnd);
     // mmap the low shadow plus at least one page at the left.
     ReserveShadowMemoryRange(shadow_start, kLowShadowEnd);
Index: lib/sanitizer_common/sanitizer_common.h
===================================================================
--- lib/sanitizer_common/sanitizer_common.h
+++ lib/sanitizer_common/sanitizer_common.h
@@ -41,6 +41,7 @@
 uptr GetPageSize();
 uptr GetPageSizeCached();
 uptr GetMmapGranularity();
+uptr GetMaxVirtualAddress();
 // Threads
 uptr GetTid();
 uptr GetThreadSelf();
Index: lib/sanitizer_common/sanitizer_win.cc
===================================================================
--- lib/sanitizer_common/sanitizer_win.cc
+++ lib/sanitizer_common/sanitizer_win.cc
@@ -40,6 +40,12 @@
   return 1U << 16;  // FIXME: is this configurable?
 }
 
+uptr GetMaxVirtualAddress() {
+  SYSTEM_INFO si;
+  GetSystemInfo(&si);
+  return (uptr)si.lpMaximumApplicationAddress;
+}
+
 bool FileExists(const char *filename) {
   UNIMPLEMENTED();
 }
Index: lib/sanitizer_common/sanitizer_posix.cc
===================================================================
--- lib/sanitizer_common/sanitizer_posix.cc
+++ lib/sanitizer_common/sanitizer_posix.cc
@@ -29,6 +29,24 @@
   return GetPageSize();
 }
 
+uptr GetMaxVirtualAddress() {
+#if SANITIZER_WORDSIZE == 64
+# if defined(__powerpc64__)
+  // On PowerPC64 we have two different address space layouts: 44- and 46-bit.
+  // We somehow need to figure our which one we are using now and choose
+  // one of 0x00000fffffffffffUL and 0x00003fffffffffffUL.
+  // Note that with 'ulimit -s unlimited' the stack is moved away from the top
+  // of the address space, so simply checking the stack address is not enough.
+  return (1ULL << 44) - 1;  // 0x00000fffffffffffUL
+# else
+  return (1ULL << 47) - 1;  // 0x00007fffffffffffUL;
+# endif
+#else  // SANITIZER_WORDSIZE == 32
+  // FIXME: We can probably lower this on Android?
+  return (1ULL << 32) - 1;  // 0xffffffff;
+#endif  // SANITIZER_WORDSIZE
+}
+
 void *MmapOrDie(uptr size, const char *mem_type) {
   size = RoundUpTo(size, GetPageSizeCached());
   uptr res = internal_mmap(0, size,
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