1 files changed, 148 insertions, 0 deletions
diff --git a/contrib/llvm-project/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp b/contrib/llvm-project/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp
new file mode 100644
index 000000000000..48bc3b631ac0
--- /dev/null
+++ b/contrib/llvm-project/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp
@@ -0,0 +1,148 @@
+//===-- hwasan_dynamic_shadow.cpp -------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file is a part of HWAddressSanitizer. It reserves dynamic shadow memory
+/// region and handles ifunc resolver case, when necessary.
+///
+//===----------------------------------------------------------------------===//
+
+#include "hwasan_dynamic_shadow.h"
+
+#include <elf.h>
+#include <link.h>
+
+#include "hwasan.h"
+#include "hwasan_mapping.h"
+#include "hwasan_thread_list.h"
+#include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_posix.h"
+
+// The code in this file needs to run in an unrelocated binary. It should not
+// access any external symbol, including its own non-hidden globals.
+
+#if SANITIZER_ANDROID
+extern "C" {
+
+INTERFACE_ATTRIBUTE void __hwasan_shadow();
+decltype(__hwasan_shadow)* __hwasan_premap_shadow();
+
+}  // extern "C"
+
+namespace __hwasan {
+
+// We cannot call anything in libc here (see comment above), so we need to
+// assume the biggest allowed page size.
+// Android max page size is defined as 16k here:
+// https://android.googlesource.com/platform/bionic/+/main/libc/platform/bionic/page.h#41
+static constexpr uptr kMaxGranularity = 16384;
+
+// Conservative upper limit.
+static uptr PremapShadowSize() {
+  return RoundUpTo(GetMaxVirtualAddress() >> kShadowScale, kMaxGranularity);
+}
+
+static uptr PremapShadow() {
+  return MapDynamicShadow(PremapShadowSize(), kShadowScale,
+                          kShadowBaseAlignment, kHighMemEnd, kMaxGranularity);
+}
+
+static bool IsPremapShadowAvailable() {
+  const uptr shadow = reinterpret_cast<uptr>(&__hwasan_shadow);
+  const uptr resolver = reinterpret_cast<uptr>(&__hwasan_premap_shadow);
+  // shadow == resolver is how Android KitKat and older handles ifunc.
+  // shadow == 0 just in case.
+  return shadow != 0 && shadow != resolver;
+}
+
+static uptr FindPremappedShadowStart(uptr shadow_size_bytes) {
+  const uptr granularity = kMaxGranularity;
+  const uptr shadow_start = reinterpret_cast<uptr>(&__hwasan_shadow);
+  const uptr premap_shadow_size = PremapShadowSize();
+  const uptr shadow_size = RoundUpTo(shadow_size_bytes, granularity);
+
+  // We may have mapped too much. Release extra memory.
+  UnmapFromTo(shadow_start + shadow_size, shadow_start + premap_shadow_size);
+  return shadow_start;
+}
+
+}  // namespace __hwasan
+
+extern "C" {
+
+decltype(__hwasan_shadow)* __hwasan_premap_shadow() {
+  // The resolver might be called multiple times. Map the shadow just once.
+  static __sanitizer::uptr shadow = 0;
+  if (!shadow)
+    shadow = __hwasan::PremapShadow();
+  return reinterpret_cast<decltype(__hwasan_shadow)*>(shadow);
+}
+
+// __hwasan_shadow is a "function" that has the same address as the first byte
+// of the shadow mapping.
+INTERFACE_ATTRIBUTE __attribute__((ifunc("__hwasan_premap_shadow")))
+void __hwasan_shadow();
+
+extern __attribute((weak, visibility("hidden"))) ElfW(Rela) __rela_iplt_start[],
+    __rela_iplt_end[];
+
+}  // extern "C"
+
+namespace __hwasan {
+
+void InitShadowGOT() {
+  // Call the ifunc resolver for __hwasan_shadow and fill in its GOT entry. This
+  // needs to be done before other ifunc resolvers (which are handled by libc)
+  // because a resolver might read __hwasan_shadow.
+  typedef ElfW(Addr) (*ifunc_resolver_t)(void);
+  for (ElfW(Rela) *r = __rela_iplt_start; r != __rela_iplt_end; ++r) {
+    ElfW(Addr)* offset = reinterpret_cast<ElfW(Addr)*>(r->r_offset);
+    ElfW(Addr) resolver = r->r_addend;
+    if (resolver == reinterpret_cast<ElfW(Addr)>(&__hwasan_premap_shadow)) {
+      *offset = reinterpret_cast<ifunc_resolver_t>(resolver)();
+      break;
+    }
+  }
+}
+
+uptr FindDynamicShadowStart(uptr shadow_size_bytes) {
+  if (IsPremapShadowAvailable())
+    return FindPremappedShadowStart(shadow_size_bytes);
+  return MapDynamicShadow(shadow_size_bytes, kShadowScale, kShadowBaseAlignment,
+                          kHighMemEnd, kMaxGranularity);
+}
+
+}  // namespace __hwasan
+
+#elif SANITIZER_FUCHSIA
+
+namespace __hwasan {
+
+void InitShadowGOT() {}
+
+}  // namespace __hwasan
+
+#else
+namespace __hwasan {
+
+void InitShadowGOT() {}
+
+uptr FindDynamicShadowStart(uptr shadow_size_bytes) {
+#  if defined(HWASAN_ALIASING_MODE)
+  constexpr uptr kAliasSize = 1ULL << kAddressTagShift;
+  constexpr uptr kNumAliases = 1ULL << kTagBits;
+  return MapDynamicShadowAndAliases(shadow_size_bytes, kAliasSize, kNumAliases,
+                                    RingBufferSize());
+#  endif
+  return MapDynamicShadow(shadow_size_bytes, kShadowScale, kShadowBaseAlignment,
+                          kHighMemEnd, GetMmapGranularity());
+}
+
+}  // namespace __hwasan
+
+#endif  // SANITIZER_ANDROID