[compiler-rt] [dfsan] Unify aarch64 mapping

[zatrazz]

Summary

This patch reorganize the platform specific mapping information to
export the application mask on a external variable. This exported
variable will be used by intrumentation phase to create code to be
used on architecture with multiple VMA range.

The patch creates a new header, dfsan_platform.h, and move all the
mapping information and also create function accessors to the
mapping value. Also for aarch64 it initialize application exported
mask to the value based on runtime VMA detection.

[pcc]

lib/dfsan/dfsan.cc

371

You don't need this #ifdef (or the macro), as it is redundant with __aarch64__.

378

ThreadSanitizer -> DataFlowSanitizer

lib/dfsan/dfsan_platform.h

93

I would prefer if these functions were written more directly.

e.g.

uptr UnionTableAddr() {
#if defined(__x86_64__)
  return 0x200000000000;
#elif ...
#elif defined(__aarch64__)
  if (vmaSize == 39)
    return ...;
  else
    return ...;
#endif
}

[zatrazz]

Thanks for the review, comments below.

lib/dfsan/dfsan.cc

371

The idea of adding these two ifdefs, although currently redundant, is to make explicit DFSAN_RUNTIME_VMA is not tied to aarch64. I can remove it if you prefer.

378

I will change that.

lib/dfsan/dfsan_platform.h

93

I based this modifications on my pending thread sanitizer patch [1] and the idea it avoid the constant ifdef for multiple function which IHMO only make the code hard to read and duplicate logic. Which this approach you have only two required platform specific blocks: one for the mapping definition and other for multiple VMA handling. I sensed, based on thread sanitizer review, that this approach would be desirable one for compiler-rt.

[1] http://reviews.llvm.org/D14199

[dvyukov]

Yes, this is based on my proposal for tsan. Tsan supports more mappings, logic is more complex and requires more constants. So I wanted to (1) see all constants in a single place (Mapping struct) and (2) don't duplicate any mapping related functions.

[pcc]

lib/dfsan/dfsan.cc

371

I'd prefer to remove it. We can always add it back if it becomes necessary.

lib/dfsan/dfsan_platform.h

93

Okay, let's be consistent with TSan here.

[zatrazz]

Changes from previous version:

• Remove aarch64 ifdef on PlatformEarlyInit.

[zatrazz]

Ping. The llvm side is already approved [1].

[1] http://reviews.llvm.org/D14724

[pcc]

Lgtm

[zatrazz]

Accepted baded on 'pcc' comment.

lib/dfsan/dfsan.h

 //
 // Private DFSan header.
 //===----------------------------------------------------------------------===//
 
 #ifndef DFSAN_H
 #define DFSAN_H
 
 #include "sanitizer_common/sanitizer_internal_defs.h"
+#include "dfsan_platform.h"
 
 // Copy declarations from public sanitizer/dfsan_interface.h header here.
 typedef u16 dfsan_label;
 
 struct dfsan_label_info {
   dfsan_label l1;
   dfsan_label l2;
   const char *desc;
void dfsan_set_label(dfsan_label label, T &data) {  // NOLINT
   dfsan_set_label(label, (void *)&data, sizeof(T));
 }
 
 namespace __dfsan {
 
 void InitializeInterceptors();
 
 inline dfsan_label *shadow_for(void *ptr) {
-#if defined(__x86_64__)
-  return (dfsan_label *) ((((uptr) ptr) & ~0x700000000000) << 1);
-#elif defined(__mips64)
-  return (dfsan_label *) ((((uptr) ptr) & ~0xF000000000) << 1);
-#elif defined(__aarch64__)
-# if SANITIZER_AARCH64_VMA == 39
-  return (dfsan_label *) ((((uptr) ptr) & ~0x7800000000) << 1);
-# elif SANITIZER_AARCH64_VMA == 42
-  return (dfsan_label *) ((((uptr) ptr) & ~0x3c000000000) << 1);
-# endif
-#endif
+  return (dfsan_label *) ((((uptr) ptr) & ShadowMask()) << 1);
 }
 
 inline const dfsan_label *shadow_for(const void *ptr) {
   return shadow_for(const_cast<void *>(ptr));
 }
 
 struct Flags {
 #define DFSAN_FLAG(Type, Name, DefaultValue, Description) Type Name;

lib/dfsan/dfsan.cc

 static atomic_dfsan_label __dfsan_last_label;
 static dfsan_label_info __dfsan_label_info[kNumLabels];
 
 Flags __dfsan::flags_data;
 
 SANITIZER_INTERFACE_ATTRIBUTE THREADLOCAL dfsan_label __dfsan_retval_tls;
 SANITIZER_INTERFACE_ATTRIBUTE THREADLOCAL dfsan_label __dfsan_arg_tls[64];
 
+SANITIZER_INTERFACE_ATTRIBUTE uptr __dfsan_shadow_ptr_mask;
+
 // On Linux/x86_64, memory is laid out as follows:
 //
 // +--------------------+ 0x800000000000 (top of memory)
 // | application memory |
 // +--------------------+ 0x700000008000 (kAppAddr)
 // |                    |
 // |       unused       |
 // |                    |

 // +--------------------+ 0x8000000000 (kUnionTableAddr)
 // |   shadow memory    |
 // +--------------------+ 0x0000010000 (kShadowAddr)
 // | reserved by kernel |
 // +--------------------+ 0x0000000000
 
 typedef atomic_dfsan_label dfsan_union_table_t[kNumLabels][kNumLabels];
 
-#if defined(__x86_64__)
-static const uptr kShadowAddr = 0x10000;
-static const uptr kUnionTableAddr = 0x200000000000;
-static const uptr kUnusedAddr = kUnionTableAddr + sizeof(dfsan_union_table_t);
-static const uptr kAppAddr = 0x700000008000;
-#elif defined(__mips64)
-static const uptr kShadowAddr = 0x10000;
-static const uptr kUnionTableAddr = 0x2000000000;
-static const uptr kUnusedAddr = kUnionTableAddr + sizeof(dfsan_union_table_t);
-static const uptr kAppAddr = 0xF000008000;
-#elif defined(__aarch64__)
-static const uptr kShadowAddr = 0x10000;
-# if SANITIZER_AARCH64_VMA == 39
-static const uptr kUnionTableAddr = 0x1000000000;
-# elif SANITIZER_AARCH64_VMA == 42
-static const uptr kUnionTableAddr = 0x8000000000;
-# endif
-static const uptr kUnusedAddr = kUnionTableAddr + sizeof(dfsan_union_table_t);
-# if SANITIZER_AARCH64_VMA == 39
-static const uptr kAppAddr = 0x7000008000;
-# elif SANITIZER_AARCH64_VMA == 42
-static const uptr kAppAddr = 0x3ff00008000;
-# endif
-#else
-# error "DFSan not supported for this platform!"
+#ifdef DFSAN_RUNTIME_VMA
+// Runtime detected VMA size.
+int __dfsan::vmaSize;
 #endif
 
+static uptr UnusedAddr() {
+  return MappingArchImpl<MAPPING_UNION_TABLE_ADDR>()
+         + sizeof(dfsan_union_table_t);
+}
+
 static atomic_dfsan_label *union_table(dfsan_label l1, dfsan_label l2) {
-  return &(*(dfsan_union_table_t *) kUnionTableAddr)[l1][l2];
+  return &(*(dfsan_union_table_t *) UnionTableAddr())[l1][l2];
 }
 
 // Checks we do not run out of labels.
 static void dfsan_check_label(dfsan_label label) {
   if (label == kInitializingLabel) {
     Report("FATAL: DataFlowSanitizer: out of labels\n");
     Die();
   }
static void InitializeFlags() {
   RegisterCommonFlags(&parser);
   RegisterDfsanFlags(&parser, &flags());
   parser.ParseString(GetEnv("DFSAN_OPTIONS"));
   SetVerbosity(common_flags()->verbosity);
   if (Verbosity()) ReportUnrecognizedFlags();
   if (common_flags()->help) parser.PrintFlagDescriptions();
 }
 
+static void InitializePlatformEarly() {
+#ifdef DFSAN_RUNTIME_VMA
+  __dfsan::vmaSize =
+    (MostSignificantSetBitIndex(GET_CURRENT_FRAME()) + 1);
+  if (__dfsan::vmaSize == 39 || __dfsan::vmaSize == 42) {
+    __dfsan_shadow_ptr_mask = ShadowMask();
+  } else {
+    Printf("FATAL: DataFlowSanitizer: unsupported VMA range\n");
+    Printf("FATAL: Found %d - Supported 39 and 42\n", __dfsan::vmaSize);
+    Die();
+  }
+#endif
+}
+
 static void dfsan_fini() {
   if (internal_strcmp(flags().dump_labels_at_exit, "") != 0) {
     fd_t fd = OpenFile(flags().dump_labels_at_exit, WrOnly);
     if (fd == kInvalidFd) {
       Report("WARNING: DataFlowSanitizer: unable to open output file %s\n",
              flags().dump_labels_at_exit);
       return;
     }
 
     Report("INFO: DataFlowSanitizer: dumping labels to %s\n",
            flags().dump_labels_at_exit);
     dfsan_dump_labels(fd);
     CloseFile(fd);
   }
 }
 
 static void dfsan_init(int argc, char **argv, char **envp) {
   InitializeFlags();
 
-  CheckVMASize();
+  InitializePlatformEarly();
 
-  MmapFixedNoReserve(kShadowAddr, kUnusedAddr - kShadowAddr);
+  MmapFixedNoReserve(ShadowAddr(), UnusedAddr() - ShadowAddr());
 
   // Protect the region of memory we don't use, to preserve the one-to-one
   // mapping from application to shadow memory. But if ASLR is disabled, Linux
   // will load our executable in the middle of our unused region. This mostly
   // works so long as the program doesn't use too much memory. We support this
   // case by disabling memory protection when ASLR is disabled.
   uptr init_addr = (uptr)&dfsan_init;
-  if (!(init_addr >= kUnusedAddr && init_addr < kAppAddr))
-    MmapNoAccess(kUnusedAddr, kAppAddr - kUnusedAddr);
+  if (!(init_addr >= UnusedAddr() && init_addr < AppAddr()))
+    MmapNoAccess(UnusedAddr(), AppAddr() - UnusedAddr());
 
   InitializeInterceptors();
 
   // Register the fini callback to run when the program terminates successfully
   // or it is killed by the runtime.
   Atexit(dfsan_fini);
   AddDieCallback(dfsan_fini);
 
   __dfsan_label_info[kInitializingLabel].desc = "<init label>";
 }
 
 #if SANITIZER_CAN_USE_PREINIT_ARRAY
 __attribute__((section(".preinit_array"), used))
 static void (*dfsan_init_ptr)(int, char **, char **) = dfsan_init;
 #endif

lib/dfsan/dfsan_platform.h

+//===-- dfsan_platform.h ----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of DataFlowSanitizer.
+//
+// Platform specific information for DFSan.
+//===----------------------------------------------------------------------===//
+
+#ifndef DFSAN_PLATFORM_H
+#define DFSAN_PLATFORM_H
+
+namespace __dfsan {
+
+#if defined(__x86_64__)
+struct Mapping {
+  static const uptr kShadowAddr = 0x10000;
+  static const uptr kUnionTableAddr = 0x200000000000;
+  static const uptr kAppAddr = 0x700000008000;
+  static const uptr kShadowMask = ~0x700000000000;
+};
+#elif defined(__mips64)
+struct Mapping {
+  static const uptr kShadowAddr = 0x10000;
+  static const uptr kUnionTableAddr = 0x2000000000;
+  static const uptr kAppAddr = 0xF000008000;
+  static const uptr kShadowMask = ~0xF000000000;
+};
+#elif defined(__aarch64__)
+struct Mapping39 {
+  static const uptr kShadowAddr = 0x10000;
+  static const uptr kUnionTableAddr = 0x1000000000;
+  static const uptr kAppAddr = 0x7000008000;
+  static const uptr kShadowMask = ~0x7800000000;
+};
+
+struct Mapping42 {
+  static const uptr kShadowAddr = 0x10000;
+  static const uptr kUnionTableAddr = 0x8000000000;
+  static const uptr kAppAddr = 0x3ff00008000;
+  static const uptr kShadowMask = ~0x3c000000000;
+};
+
+extern int vmaSize;
+# define DFSAN_RUNTIME_VMA 1
+#else
+# error "DFSan not supported for this platform!"
+#endif
+
+enum MappingType {
+  MAPPING_SHADOW_ADDR,
+  MAPPING_UNION_TABLE_ADDR,
+  MAPPING_APP_ADDR,
+  MAPPING_SHADOW_MASK
+};
+
+template<typename Mapping, int Type>
+uptr MappingImpl(void) {
+  switch (Type) {
+    case MAPPING_SHADOW_ADDR: return Mapping::kShadowAddr;
+    case MAPPING_UNION_TABLE_ADDR: return Mapping::kUnionTableAddr;
+    case MAPPING_APP_ADDR: return Mapping::kAppAddr;
+    case MAPPING_SHADOW_MASK: return Mapping::kShadowMask;
+  }
+}
+
+template<int Type>
+uptr MappingArchImpl(void) {
+#ifdef __aarch64__
+  if (vmaSize == 39)
+    return MappingImpl<Mapping39, Type>();
+  else
+    return MappingImpl<Mapping42, Type>();
+  DCHECK(0);
+#else
+  return MappingImpl<Mapping, Type>();
+#endif
+}
+
+ALWAYS_INLINE
+uptr ShadowAddr() {
+  return MappingArchImpl<MAPPING_SHADOW_ADDR>();
+}
+
+ALWAYS_INLINE
+uptr UnionTableAddr() {
+  return MappingArchImpl<MAPPING_UNION_TABLE_ADDR>();
+}
+
+ALWAYS_INLINE
+uptr AppAddr() {
+  return MappingArchImpl<MAPPING_APP_ADDR>();
+}
+
+ALWAYS_INLINE
+uptr ShadowMask() {
+  return MappingArchImpl<MAPPING_SHADOW_MASK>();
+}
+
+}  // namespace __dfsan
+
+#endif