1 files changed, 125 insertions, 0 deletions
diff --git a/contrib/llvm-project/compiler-rt/lib/asan/asan_shadow_setup.cpp b/contrib/llvm-project/compiler-rt/lib/asan/asan_shadow_setup.cpp
new file mode 100644
index 000000000000..fc6de39622b5
--- /dev/null
+++ b/contrib/llvm-project/compiler-rt/lib/asan/asan_shadow_setup.cpp
@@ -0,0 +1,125 @@
+//===-- asan_shadow_setup.cpp ---------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// Set up the shadow memory.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common/sanitizer_platform.h"
+
+// asan_fuchsia.cpp has their own InitializeShadowMemory implementation.
+#if !SANITIZER_FUCHSIA
+
+#  include "asan_internal.h"
+#  include "asan_mapping.h"
+
+namespace __asan {
+
+static void ProtectGap(uptr addr, uptr size) {
+  if (!flags()->protect_shadow_gap) {
+    // The shadow gap is unprotected, so there is a chance that someone
+    // is actually using this memory. Which means it needs a shadow...
+    uptr GapShadowBeg = RoundDownTo(MEM_TO_SHADOW(addr), GetPageSizeCached());
+    uptr GapShadowEnd =
+        RoundUpTo(MEM_TO_SHADOW(addr + size), GetPageSizeCached()) - 1;
+    if (Verbosity())
+      Printf(
+          "protect_shadow_gap=0:"
+          " not protecting shadow gap, allocating gap's shadow\n"
+          "|| `[%p, %p]` || ShadowGap's shadow ||\n",
+          (void*)GapShadowBeg, (void*)GapShadowEnd);
+    ReserveShadowMemoryRange(GapShadowBeg, GapShadowEnd,
+                             "unprotected gap shadow");
+    return;
+  }
+  __sanitizer::ProtectGap(addr, size, kZeroBaseShadowStart,
+                          kZeroBaseMaxShadowStart);
+}
+
+static void MaybeReportLinuxPIEBug() {
+#if SANITIZER_LINUX && \
+    (defined(__x86_64__) || defined(__aarch64__) || SANITIZER_RISCV64)
+  Report("This might be related to ELF_ET_DYN_BASE change in Linux 4.12.\n");
+  Report(
+      "See https://github.com/google/sanitizers/issues/856 for possible "
+      "workarounds.\n");
+#endif
+}
+
+void InitializeShadowMemory() {
+  // Set the shadow memory address to uninitialized.
+  __asan_shadow_memory_dynamic_address = kDefaultShadowSentinel;
+
+  uptr shadow_start = kLowShadowBeg;
+  // Detect if a dynamic shadow address must used and find a available location
+  // when necessary. When dynamic address is used, the macro |kLowShadowBeg|
+  // expands to |__asan_shadow_memory_dynamic_address| which is
+  // |kDefaultShadowSentinel|.
+  bool full_shadow_is_available = false;
+  if (shadow_start == kDefaultShadowSentinel) {
+    shadow_start = FindDynamicShadowStart();
+    if (SANITIZER_LINUX) full_shadow_is_available = true;
+  }
+  // Update the shadow memory address (potentially) used by instrumentation.
+  __asan_shadow_memory_dynamic_address = shadow_start;
+
+  if (kLowShadowBeg) shadow_start -= GetMmapGranularity();
+
+  if (!full_shadow_is_available)
+    full_shadow_is_available =
+        MemoryRangeIsAvailable(shadow_start, kHighShadowEnd);
+
+#if SANITIZER_LINUX && defined(__x86_64__) && defined(_LP64) && \
+    !ASAN_FIXED_MAPPING
+  if (!full_shadow_is_available) {
+    kMidMemBeg = kLowMemEnd < 0x3000000000ULL ? 0x3000000000ULL : 0;
+    kMidMemEnd = kLowMemEnd < 0x3000000000ULL ? 0x4fffffffffULL : 0;
+  }
+#endif
+
+  if (Verbosity()) PrintAddressSpaceLayout();
+
+  if (full_shadow_is_available) {
+    // mmap the low shadow plus at least one page at the left.
+    if (kLowShadowBeg)
+      ReserveShadowMemoryRange(shadow_start, kLowShadowEnd, "low shadow");
+    // mmap the high shadow.
+    ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd, "high shadow");
+    // protect the gap.
+    ProtectGap(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
+    CHECK_EQ(kShadowGapEnd, kHighShadowBeg - 1);
+  } else if (kMidMemBeg &&
+             MemoryRangeIsAvailable(shadow_start, kMidMemBeg - 1) &&
+             MemoryRangeIsAvailable(kMidMemEnd + 1, kHighShadowEnd)) {
+    CHECK(kLowShadowBeg != kLowShadowEnd);
+    // mmap the low shadow plus at least one page at the left.
+    ReserveShadowMemoryRange(shadow_start, kLowShadowEnd, "low shadow");
+    // mmap the mid shadow.
+    ReserveShadowMemoryRange(kMidShadowBeg, kMidShadowEnd, "mid shadow");
+    // mmap the high shadow.
+    ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd, "high shadow");
+    // protect the gaps.
+    ProtectGap(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
+    ProtectGap(kShadowGap2Beg, kShadowGap2End - kShadowGap2Beg + 1);
+    ProtectGap(kShadowGap3Beg, kShadowGap3End - kShadowGap3Beg + 1);
+  } else {
+    Report(
+        "Shadow memory range interleaves with an existing memory mapping. "
+        "ASan cannot proceed correctly. ABORTING.\n");
+    Report("ASan shadow was supposed to be located in the [%p-%p] range.\n",
+           (void*)shadow_start, (void*)kHighShadowEnd);
+    MaybeReportLinuxPIEBug();
+    DumpProcessMap();
+    Die();
+  }
+}
+
+}  // namespace __asan
+
+#endif  // !SANITIZER_FUCHSIA