[ASan] Use dynamic shadow on 32-bit iOS and simulators

[yln]

Summary

The VM layout on iOS is not stable between releases. On 64-bit iOS and
its derivatives we use a dynamic shadow offset that enables ASan to
search for a valid location for the shadow heap on process launch rather
than hardcode it.

This commit extends that approach for 32-bit iOS plus derivatives and
their simulators.

Associated radars:
rdar://50645192
rdar://51200372
rdar://51767702

[delcypher]

LGTM.

compiler-rt/lib/asan/asan_mapping.h

 #else
 static const u64 kDefaultShadowScale = SANITIZER_MYRIAD2 ? 5 : 3;
 #endif
 static const u64 kDefaultShadowSentinel = ~(uptr)0;
 static const u64 kDefaultShadowOffset32 = 1ULL << 29;  // 0x20000000
 static const u64 kDefaultShadowOffset64 = 1ULL << 44;
 static const u64 kDefaultShort64bitShadowOffset =
     0x7FFFFFFF & (~0xFFFULL << kDefaultShadowScale);  // < 2G.
-static const u64 kIosShadowOffset32 = 1ULL << 30;  // 0x40000000
-static const u64 kIosShadowOffset64 = 0x120200000;
-static const u64 kIosSimShadowOffset32 = 1ULL << 30;
-static const u64 kIosSimShadowOffset64 = kDefaultShadowOffset64;
 static const u64 kAArch64_ShadowOffset64 = 1ULL << 36;
 static const u64 kMIPS32_ShadowOffset32 = 0x0aaa0000;
 static const u64 kMIPS64_ShadowOffset64 = 1ULL << 37;
 static const u64 kPPC64_ShadowOffset64 = 1ULL << 44;
 static const u64 kSystemZ_ShadowOffset64 = 1ULL << 52;
 static const u64 kSPARC64_ShadowOffset64 = 1ULL << 43;  // 0x80000000000
 static const u64 kFreeBSD_ShadowOffset32 = 1ULL << 30;  // 0x40000000
 static const u64 kFreeBSD_ShadowOffset64 = 1ULL << 46;  // 0x400000000000

 #    define SHADOW_OFFSET kMIPS32_ShadowOffset32
 #  elif SANITIZER_FREEBSD
 #    define SHADOW_OFFSET kFreeBSD_ShadowOffset32
 #  elif SANITIZER_NETBSD
 #    define SHADOW_OFFSET kNetBSD_ShadowOffset32
 #  elif SANITIZER_WINDOWS
 #    define SHADOW_OFFSET kWindowsShadowOffset32
 #  elif SANITIZER_IOS
-#    if SANITIZER_IOSSIM
-#      define SHADOW_OFFSET kIosSimShadowOffset32
-#    else
-#      define SHADOW_OFFSET kIosShadowOffset32
-#    endif
+#    define SHADOW_OFFSET __asan_shadow_memory_dynamic_address
 #  elif SANITIZER_MYRIAD2
 #    define SHADOW_OFFSET kMyriadShadowOffset32
 #  else
 #    define SHADOW_OFFSET kDefaultShadowOffset32
 #  endif
 #else
 #  if SANITIZER_IOS
-#    if SANITIZER_IOSSIM
-#      define SHADOW_OFFSET kIosSimShadowOffset64
-#    else
-#      define SHADOW_OFFSET __asan_shadow_memory_dynamic_address
-#    endif
+#    define SHADOW_OFFSET __asan_shadow_memory_dynamic_address
 #  elif defined(__aarch64__)
 #    define SHADOW_OFFSET kAArch64_ShadowOffset64
 #  elif defined(__powerpc64__)
 #    define SHADOW_OFFSET kPPC64_ShadowOffset64
 #  elif defined(__s390x__)
 #    define SHADOW_OFFSET kSystemZ_ShadowOffset64
 #  elif SANITIZER_FREEBSD
 #    define SHADOW_OFFSET kFreeBSD_ShadowOffset64

compiler-rt/lib/sanitizer_common/sanitizer_mac.cc

void MaybeReexec() {
   LeakyResetEnv(kDyldInsertLibraries, new_env);
 }
 #endif  // SANITIZER_GO
 
 char **GetArgv() {
   return *_NSGetArgv();
 }
 
-#if defined(__aarch64__) && SANITIZER_IOS && !SANITIZER_IOSSIM
+#if SANITIZER_IOS
 // The task_vm_info struct is normally provided by the macOS SDK, but we need
 // fields only available in 10.12+. Declare the struct manually to be able to
 // build against older SDKs.
 struct __sanitizer_task_vm_info {
   mach_vm_size_t virtual_size;
   integer_t region_count;
   integer_t page_size;
   mach_vm_size_t resident_size;
struct __sanitizer_task_vm_info {
   mach_vm_size_t compressed_lifetime;
   mach_vm_size_t phys_footprint;
   mach_vm_address_t min_address;
   mach_vm_address_t max_address;
 };
 #define __SANITIZER_TASK_VM_INFO_COUNT ((mach_msg_type_number_t) \
     (sizeof(__sanitizer_task_vm_info) / sizeof(natural_t)))
 
-uptr GetTaskInfoMaxAddress() {
+static uptr GetTaskInfoMaxAddress() {
   __sanitizer_task_vm_info vm_info = {} /* zero initialize */;
   mach_msg_type_number_t count = __SANITIZER_TASK_VM_INFO_COUNT;
   int err = task_info(mach_task_self(), TASK_VM_INFO, (int *)&vm_info, &count);
-  if (err == 0 && vm_info.max_address != 0) {
-    return vm_info.max_address - 1;
-  } else {
-    // xnu cannot provide vm address limit
-    return 0x200000000 - 1;
-  }
-}
-#endif
+  return err ? 0 : vm_info.max_address;
+}
+
+uptr GetMaxUserVirtualAddress() {
+  static uptr max_vm = GetTaskInfoMaxAddress();
+  if (max_vm != 0)
+    return max_vm - 1;
+
+# if SANITIZER_WORDSIZE == 32
+  return 0xffe00000 - 1;
+# else
+# endif
+}
+
+#else // !SANITIZER_IOS
 
 uptr GetMaxUserVirtualAddress() {
-#if SANITIZER_WORDSIZE == 64
-# if defined(__aarch64__) && SANITIZER_IOS && !SANITIZER_IOSSIM
-  // Get the maximum VM address
-  static uptr max_vm = GetTaskInfoMaxAddress();
-  CHECK(max_vm);
-  return max_vm;
-# else
+# if SANITIZER_WORDSIZE == 64
   return (1ULL << 47) - 1;  // 0x00007fffffffffffUL;
-# endif
-#else  // SANITIZER_WORDSIZE == 32
+# else // SANITIZER_WORDSIZE == 32
+  static_assert(SANITIZER_WORDSIZE == 32, "Wrong wordsize");
   return (1ULL << 32) - 1;  // 0xffffffff;
-#endif  // SANITIZER_WORDSIZE
+# endif
 }
+#endif
 
 uptr GetMaxVirtualAddress() {
   return GetMaxUserVirtualAddress();
 }
 
 uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding,
                               uptr *largest_gap_found,
                               uptr *max_occupied_addr) {

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

 
 #define DEBUG_TYPE "asan"
 
 static const uint64_t kDefaultShadowScale = 3;
 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
 static const uint64_t kDynamicShadowSentinel =
     std::numeric_limits<uint64_t>::max();
-static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
-static const uint64_t kIOSSimShadowOffset32 = 1ULL << 30;
-static const uint64_t kIOSSimShadowOffset64 = kDefaultShadowOffset64;
 static const uint64_t kSmallX86_64ShadowOffsetBase = 0x7FFFFFFF;  // < 2G.
 static const uint64_t kSmallX86_64ShadowOffsetAlignMask = ~0xFFFULL;
 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 44;
 static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
   bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
   bool IsFreeBSD = TargetTriple.isOSFreeBSD();
   bool IsNetBSD = TargetTriple.isOSNetBSD();
   bool IsPS4CPU = TargetTriple.isPS4CPU();
   bool IsLinux = TargetTriple.isOSLinux();
   bool IsPPC64 = TargetTriple.getArch() == Triple::ppc64 ||
                  TargetTriple.getArch() == Triple::ppc64le;
   bool IsSystemZ = TargetTriple.getArch() == Triple::systemz;
-  bool IsX86 = TargetTriple.getArch() == Triple::x86;
   bool IsX86_64 = TargetTriple.getArch() == Triple::x86_64;
   bool IsMIPS32 = TargetTriple.isMIPS32();
   bool IsMIPS64 = TargetTriple.isMIPS64();
   bool IsArmOrThumb = TargetTriple.isARM() || TargetTriple.isThumb();
   bool IsAArch64 = TargetTriple.getArch() == Triple::aarch64;
   bool IsWindows = TargetTriple.isOSWindows();
   bool IsFuchsia = TargetTriple.isOSFuchsia();
   bool IsMyriad = TargetTriple.getVendor() == llvm::Triple::Myriad;
if (IsAndroid)
       Mapping.Offset = kDynamicShadowSentinel;
     else if (IsMIPS32)
       Mapping.Offset = kMIPS32_ShadowOffset32;
     else if (IsFreeBSD)
       Mapping.Offset = kFreeBSD_ShadowOffset32;
     else if (IsNetBSD)
       Mapping.Offset = kNetBSD_ShadowOffset32;
     else if (IsIOS)
-      // If we're targeting iOS and x86, the binary is built for iOS simulator.
-      Mapping.Offset = IsX86 ? kIOSSimShadowOffset32 : kIOSShadowOffset32;
+      Mapping.Offset = kDynamicShadowSentinel;
     else if (IsWindows)
       Mapping.Offset = kWindowsShadowOffset32;
     else if (IsMyriad) {
       uint64_t ShadowOffset = (kMyriadMemoryOffset32 + kMyriadMemorySize32 -
                                (kMyriadMemorySize32 >> Mapping.Scale));
       Mapping.Offset = ShadowOffset - (kMyriadMemoryOffset32 >> Mapping.Scale);
     }
     else
else if (IsLinux && IsX86_64) {
       else
         Mapping.Offset = (kSmallX86_64ShadowOffsetBase &
                           (kSmallX86_64ShadowOffsetAlignMask << Mapping.Scale));
     } else if (IsWindows && IsX86_64) {
       Mapping.Offset = kWindowsShadowOffset64;
     } else if (IsMIPS64)
       Mapping.Offset = kMIPS64_ShadowOffset64;
     else if (IsIOS)
-      // If we're targeting iOS and x86, the binary is built for iOS simulator.
-      // We are using dynamic shadow offset on the 64-bit devices.
-      Mapping.Offset =
-        IsX86_64 ? kIOSSimShadowOffset64 : kDynamicShadowSentinel;
+      Mapping.Offset = kDynamicShadowSentinel;
     else if (IsAArch64)
       Mapping.Offset = kAArch64_ShadowOffset64;
     else
       Mapping.Offset = kDefaultShadowOffset64;
   }
 
   if (ClForceDynamicShadow) {
     Mapping.Offset = kDynamicShadowSentinel;

llvm/test/Instrumentation/AddressSanitizer/dynamic-shadow-darwin.ll

+; Test using dynamic shadow address on darwin
+;
+; RUN: opt -asan -asan-module -mtriple=arm64_32-apple-watchos --data-layout="e-m:o-p:32:32-i64:64-i128:128-n32:64-S128" -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-DYNAMIC -DPTR_SIZE=32
+; RUN: opt -asan -asan-module -mtriple=armv7k-apple-watchos --data-layout="e-m:o-p:32:32-Fi8-i64:64-a:0:32-n32-S128" -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-DYNAMIC -DPTR_SIZE=32
+; RUN: opt -asan -asan-module -mtriple=arm64-apple-ios --data-layout="e-m:o-i64:64-i128:128-n32:64-S128" -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-DYNAMIC -DPTR_SIZE=64
+; RUN: opt -asan -asan-module -mtriple=armv7s-apple-ios --data-layout="e-m:o-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32" -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-DYNAMIC -DPTR_SIZE=32
+; RUN: opt -asan -asan-module -mtriple=i386-apple-watchos-simulator --data-layout="e-m:o-p:32:32-f64:32:64-f80:128-n8:16:32-S128" -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-DYNAMIC -DPTR_SIZE=32
+; RUN: opt -asan -asan-module -mtriple=i386-apple-ios-simulator --data-layout="e-m:o-p:32:32-f64:32:64-f80:128-n8:16:32-S128" -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-DYNAMIC -DPTR_SIZE=32
+; RUN: opt -asan -asan-module -mtriple=x86_64-apple-ios-simulator --data-layout="e-m:o-i64:64-f80:128-n8:16:32:64-S128" -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-DYNAMIC -DPTR_SIZE=64
+;
+; // macOS does not use dynamic shadow placement
+; RUN: opt -asan -asan-module -mtriple=x86_64-apple-macosx --data-layout="e-m:o-i64:64-f80:128-n8:16:32:64-S128" -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-NONDYNAMIC -DPTR_SIZE=64
+
+define i32 @test_load(i32* %a) sanitize_address {
+; First instrumentation in the function must be to load the dynamic shadow
+; address into a local variable.
+; CHECK-LABEL: @test_load
+; CHECK: entry:
+; CHECK-DYNAMIC-NEXT: %[[SHADOW:[^ ]*]] = load i[[PTR_SIZE]], i[[PTR_SIZE]]* @__asan_shadow_memory_dynamic_address
+; CHECK-NONDYNAMIC-NOT: __asan_shadow_memory_dynamic_address
+
+; Shadow address is loaded and added into the whole offset computation.
+; CHECK-DYNAMIC: add i[[PTR_SIZE]] %{{.*}}, %[[SHADOW]]
+
+entry:
+  %tmp1 = load i32, i32* %a, align 4
+  ret i32 %tmp1
+}