[sanitizer_common] Add darwin-specific MemoryRangeIsAvailable

compiler-rt/lib/sanitizer_common/sanitizer_common.h

@@ -487,6 +487,13 @@ inline uptr Log2(uptr x) {
   return LeastSignificantSetBitIndex(x);
 }
 
+inline bool IntervalsAreSeparate(uptr start1, uptr end1, uptr start2,
+                                 uptr end2) {
+  CHECK_LE(start1, end1);
+  CHECK_LE(start2, end2);
+  return (end1 < start2) || (end2 < start1);
+}
+
 // Don't use std::min, std::max or std::swap, to minimize dependency
 // on libstdc++.
 template <class T>

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

@@ -103,6 +103,8 @@ extern "C" {
     natural_t *nesting_depth,
     vm_region_recurse_info_t info,
     mach_msg_type_number_t *infoCnt);
+
+  extern const void* _dyld_get_shared_cache_range(size_t* length);
 }
 
 #  if !SANITIZER_GO
@@ -1403,15 +1405,27 @@ uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding,
   return 0;
 }
 
-// Returns true if the address is definitely mapped, and false if it is not
-// mapped or could not be determined.
-bool IsAddressInMappedRegion(uptr addr) {
+// This function (when used during initialization when there is
+// only a single thread), can be used to verify that a range
+// of memory hasn't already been mapped, and won't be mapped
+// later in the shared cache.
+//
+// If the syscall mach_vm_region_recurse fails (due to sandbox),
+// we assume that the memory is not mapped so that execution can continue.
+//
+// NOTE: range_end is inclusive
+//
+// WARNING: This function must NOT allocate memory, since it is
+// used in InitializeShadowMemory between where we search for
+// space for shadow and where we actually allocate it.
+bool MemoryRangeIsAvailable(uptr range_start, uptr range_end) {
   mach_vm_size_t vmsize = 0;
   natural_t depth = 0;
   vm_region_submap_short_info_data_64_t vminfo;
   mach_msg_type_number_t count = VM_REGION_SUBMAP_SHORT_INFO_COUNT_64;
-  mach_vm_address_t address = addr;
+  mach_vm_address_t address = range_start;
 
+  // First, check if the range is already mapped.
   kern_return_t kr =
       mach_vm_region_recurse(mach_task_self(), &address, &vmsize, &depth,
                              (vm_region_info_t)&vminfo, &count);
@@ -1423,7 +1437,24 @@ bool IsAddressInMappedRegion(uptr addr) {
     Report("HINT: Is mach_vm_region_recurse allowed by sandbox?\n");
   }
 
-  return (kr == KERN_SUCCESS && addr >= address && addr < address + vmsize);
+  if (kr == KERN_SUCCESS && !IntervalsAreSeparate(address, address + vmsize - 1,
+                                                  range_start, range_end)) {
+    // Overlaps with already-mapped memory
+    return false;
+  }
+
+  size_t cacheLength;
+  uptr cacheStart = (uptr)_dyld_get_shared_cache_range(&cacheLength);
+
+  if (cacheStart &&
+      !IntervalsAreSeparate(cacheStart, cacheStart + cacheLength - 1,
+                            range_start, range_end)) {
+    // Overlaps with shared cache region
+    return false;
+  }
+
+  // We believe this address is available.
+  return true;
 }
 
 // FIXME implement on this platform.

compiler-rt/lib/sanitizer_common/sanitizer_mac.h

@@ -76,8 +76,6 @@ struct ThreadEventCallbacks {
 
 void InstallPthreadIntrospectionHook(const ThreadEventCallbacks &callbacks);
 
-bool IsAddressInMappedRegion(uptr addr);
-
 }  // namespace __sanitizer
 
 #endif  // SANITIZER_APPLE

compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp

@@ -225,17 +225,9 @@ void *MapWritableFileToMemory(void *addr, uptr size, fd_t fd, OFF_T offset) {
   return (void *)p;
 }
 
-static inline bool IntervalsAreSeparate(uptr start1, uptr end1,
-                                        uptr start2, uptr end2) {
-  CHECK(start1 <= end1);
-  CHECK(start2 <= end2);
-  return (end1 < start2) || (end2 < start1);
-}
-
+#  if !SANITIZER_APPLE
 // FIXME: this is thread-unsafe, but should not cause problems most of the time.
-// When the shadow is mapped only a single thread usually exists (plus maybe
-// several worker threads on Mac, which aren't expected to map big chunks of
-// memory).
+// When the shadow is mapped only a single thread usually exists
 bool MemoryRangeIsAvailable(uptr range_start, uptr range_end) {
   MemoryMappingLayout proc_maps(/*cache_enabled*/true);
   if (proc_maps.Error())
@@ -251,7 +243,6 @@ bool MemoryRangeIsAvailable(uptr range_start, uptr range_end) {
   return true;
 }
 
-#if !SANITIZER_APPLE
 void DumpProcessMap() {
   MemoryMappingLayout proc_maps(/*cache_enabled*/true);
   const sptr kBufSize = 4095;
@@ -265,7 +256,7 @@ void DumpProcessMap() {
   Report("End of process memory map.\n");
   UnmapOrDie(filename, kBufSize);
 }
-#endif
+#  endif
 
 const char *GetPwd() {
   return GetEnv("PWD");

compiler-rt/lib/tsan/rtl/tsan_platform_mac.cpp

@@ -235,7 +235,7 @@ void InitializePlatformEarly() {
   }
   // In some configurations, the max_vm is expanded, but much of this space is
   // already mapped. TSAN will not work in this configuration.
-  if (IsAddressInMappedRegion(HiAppMemEnd() - 1)) {
+  if (!MemoryRangeIsAvailable(HiAppMemEnd() - 1, HiAppMemEnd())) {
     Report(
         "ThreadSanitizer: Unsupported virtual memory layout: Address %p is "
         "already mapped.\n",