1 files changed, 261 insertions, 0 deletions
diff --git a/contrib/llvm-project/compiler-rt/lib/scudo/standalone/mem_map_fuchsia.cpp b/contrib/llvm-project/compiler-rt/lib/scudo/standalone/mem_map_fuchsia.cpp
new file mode 100644
index 000000000000..9d6df2bc6999
--- /dev/null
+++ b/contrib/llvm-project/compiler-rt/lib/scudo/standalone/mem_map_fuchsia.cpp
@@ -0,0 +1,261 @@
+//===-- mem_map_fuchsia.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
+//
+//===----------------------------------------------------------------------===//
+
+#include "mem_map_fuchsia.h"
+
+#include "atomic_helpers.h"
+#include "common.h"
+#include "string_utils.h"
+
+#if SCUDO_FUCHSIA
+
+#include <zircon/process.h>
+#include <zircon/status.h>
+#include <zircon/syscalls.h>
+
+namespace scudo {
+
+static void NORETURN dieOnError(zx_status_t Status, const char *FnName,
+                                uptr Size) {
+  ScopedString Error;
+  Error.append("SCUDO ERROR: %s failed with size %zuKB (%s)", FnName,
+               Size >> 10, _zx_status_get_string(Status));
+  outputRaw(Error.data());
+  die();
+}
+
+static void setVmoName(zx_handle_t Vmo, const char *Name) {
+  size_t Len = strlen(Name);
+  DCHECK_LT(Len, ZX_MAX_NAME_LEN);
+  zx_status_t Status = _zx_object_set_property(Vmo, ZX_PROP_NAME, Name, Len);
+  CHECK_EQ(Status, ZX_OK);
+}
+
+// Returns the (cached) base address of the root VMAR.
+static uptr getRootVmarBase() {
+  static atomic_uptr CachedResult = {0};
+
+  uptr Result = atomic_load(&CachedResult, memory_order_acquire);
+  if (UNLIKELY(!Result)) {
+    zx_info_vmar_t VmarInfo;
+    zx_status_t Status =
+        _zx_object_get_info(_zx_vmar_root_self(), ZX_INFO_VMAR, &VmarInfo,
+                            sizeof(VmarInfo), nullptr, nullptr);
+    CHECK_EQ(Status, ZX_OK);
+    CHECK_NE(VmarInfo.base, 0);
+
+    atomic_store(&CachedResult, VmarInfo.base, memory_order_release);
+    Result = VmarInfo.base;
+  }
+
+  return Result;
+}
+
+// Lazily creates and then always returns the same zero-sized VMO.
+static zx_handle_t getPlaceholderVmo() {
+  static atomic_u32 StoredVmo = {ZX_HANDLE_INVALID};
+
+  zx_handle_t Vmo = atomic_load(&StoredVmo, memory_order_acquire);
+  if (UNLIKELY(Vmo == ZX_HANDLE_INVALID)) {
+    // Create a zero-sized placeholder VMO.
+    zx_status_t Status = _zx_vmo_create(0, 0, &Vmo);
+    if (UNLIKELY(Status != ZX_OK))
+      dieOnError(Status, "zx_vmo_create", 0);
+
+    setVmoName(Vmo, "scudo:reserved");
+
+    // Atomically store its handle. If some other thread wins the race, use its
+    // handle and discard ours.
+    zx_handle_t OldValue = atomic_compare_exchange_strong(
+        &StoredVmo, ZX_HANDLE_INVALID, Vmo, memory_order_acq_rel);
+    if (UNLIKELY(OldValue != ZX_HANDLE_INVALID)) {
+      Status = _zx_handle_close(Vmo);
+      CHECK_EQ(Status, ZX_OK);
+
+      Vmo = OldValue;
+    }
+  }
+
+  return Vmo;
+}
+
+// Checks if MAP_ALLOWNOMEM allows the given error code.
+static bool IsNoMemError(zx_status_t Status) {
+  // Note: _zx_vmar_map returns ZX_ERR_NO_RESOURCES if the VMAR does not contain
+  // a suitable free spot.
+  return Status == ZX_ERR_NO_MEMORY || Status == ZX_ERR_NO_RESOURCES;
+}
+
+// Note: this constructor is only called by ReservedMemoryFuchsia::dispatch.
+MemMapFuchsia::MemMapFuchsia(uptr Base, uptr Capacity)
+    : MapAddr(Base), WindowBase(Base), WindowSize(Capacity) {
+  // Create the VMO.
+  zx_status_t Status = _zx_vmo_create(Capacity, 0, &Vmo);
+  if (UNLIKELY(Status != ZX_OK))
+    dieOnError(Status, "zx_vmo_create", Capacity);
+
+  setVmoName(Vmo, "scudo:dispatched");
+}
+
+bool MemMapFuchsia::mapImpl(UNUSED uptr Addr, uptr Size, const char *Name,
+                            uptr Flags) {
+  const bool AllowNoMem = !!(Flags & MAP_ALLOWNOMEM);
+  const bool PreCommit = !!(Flags & MAP_PRECOMMIT);
+  const bool NoAccess = !!(Flags & MAP_NOACCESS);
+
+  // Create the VMO.
+  zx_status_t Status = _zx_vmo_create(Size, 0, &Vmo);
+  if (UNLIKELY(Status != ZX_OK)) {
+    if (AllowNoMem && IsNoMemError(Status))
+      return false;
+    dieOnError(Status, "zx_vmo_create", Size);
+  }
+
+  if (Name != nullptr)
+    setVmoName(Vmo, Name);
+
+  // Map it.
+  zx_vm_option_t MapFlags = ZX_VM_ALLOW_FAULTS;
+  if (!NoAccess)
+    MapFlags |= ZX_VM_PERM_READ | ZX_VM_PERM_WRITE;
+  Status =
+      _zx_vmar_map(_zx_vmar_root_self(), MapFlags, 0, Vmo, 0, Size, &MapAddr);
+  if (UNLIKELY(Status != ZX_OK)) {
+    if (AllowNoMem && IsNoMemError(Status)) {
+      Status = _zx_handle_close(Vmo);
+      CHECK_EQ(Status, ZX_OK);
+
+      MapAddr = 0;
+      Vmo = ZX_HANDLE_INVALID;
+      return false;
+    }
+    dieOnError(Status, "zx_vmar_map", Size);
+  }
+
+  if (PreCommit) {
+    Status = _zx_vmar_op_range(_zx_vmar_root_self(), ZX_VMAR_OP_COMMIT, MapAddr,
+                               Size, nullptr, 0);
+    CHECK_EQ(Status, ZX_OK);
+  }
+
+  WindowBase = MapAddr;
+  WindowSize = Size;
+  return true;
+}
+
+void MemMapFuchsia::unmapImpl(uptr Addr, uptr Size) {
+  zx_status_t Status;
+
+  if (Size == WindowSize) {
+    // NOTE: Closing first and then unmapping seems slightly faster than doing
+    // the same operations in the opposite order.
+    Status = _zx_handle_close(Vmo);
+    CHECK_EQ(Status, ZX_OK);
+    Status = _zx_vmar_unmap(_zx_vmar_root_self(), Addr, Size);
+    CHECK_EQ(Status, ZX_OK);
+
+    MapAddr = WindowBase = WindowSize = 0;
+    Vmo = ZX_HANDLE_INVALID;
+  } else {
+    // Unmap the subrange.
+    Status = _zx_vmar_unmap(_zx_vmar_root_self(), Addr, Size);
+    CHECK_EQ(Status, ZX_OK);
+
+    // Decommit the pages that we just unmapped.
+    Status = _zx_vmo_op_range(Vmo, ZX_VMO_OP_DECOMMIT, Addr - MapAddr, Size,
+                              nullptr, 0);
+    CHECK_EQ(Status, ZX_OK);
+
+    if (Addr == WindowBase)
+      WindowBase += Size;
+    WindowSize -= Size;
+  }
+}
+
+bool MemMapFuchsia::remapImpl(uptr Addr, uptr Size, const char *Name,
+                              uptr Flags) {
+  const bool AllowNoMem = !!(Flags & MAP_ALLOWNOMEM);
+  const bool PreCommit = !!(Flags & MAP_PRECOMMIT);
+  const bool NoAccess = !!(Flags & MAP_NOACCESS);
+
+  // NOTE: This will rename the *whole* VMO, not only the requested portion of
+  // it. But we cannot do better than this given the MemMap API. In practice,
+  // the upper layers of Scudo always pass the same Name for a given MemMap.
+  if (Name != nullptr)
+    setVmoName(Vmo, Name);
+
+  uptr MappedAddr;
+  zx_vm_option_t MapFlags = ZX_VM_ALLOW_FAULTS | ZX_VM_SPECIFIC_OVERWRITE;
+  if (!NoAccess)
+    MapFlags |= ZX_VM_PERM_READ | ZX_VM_PERM_WRITE;
+  zx_status_t Status =
+      _zx_vmar_map(_zx_vmar_root_self(), MapFlags, Addr - getRootVmarBase(),
+                   Vmo, Addr - MapAddr, Size, &MappedAddr);
+  if (UNLIKELY(Status != ZX_OK)) {
+    if (AllowNoMem && IsNoMemError(Status))
+      return false;
+    dieOnError(Status, "zx_vmar_map", Size);
+  }
+  DCHECK_EQ(Addr, MappedAddr);
+
+  if (PreCommit) {
+    Status = _zx_vmar_op_range(_zx_vmar_root_self(), ZX_VMAR_OP_COMMIT, MapAddr,
+                               Size, nullptr, 0);
+    CHECK_EQ(Status, ZX_OK);
+  }
+
+  return true;
+}
+
+void MemMapFuchsia::releaseAndZeroPagesToOSImpl(uptr From, uptr Size) {
+  zx_status_t Status = _zx_vmo_op_range(Vmo, ZX_VMO_OP_DECOMMIT, From - MapAddr,
+                                        Size, nullptr, 0);
+  CHECK_EQ(Status, ZX_OK);
+}
+
+void MemMapFuchsia::setMemoryPermissionImpl(uptr Addr, uptr Size, uptr Flags) {
+  const bool NoAccess = !!(Flags & MAP_NOACCESS);
+
+  zx_vm_option_t MapFlags = 0;
+  if (!NoAccess)
+    MapFlags |= ZX_VM_PERM_READ | ZX_VM_PERM_WRITE;
+  zx_status_t Status =
+      _zx_vmar_protect(_zx_vmar_root_self(), MapFlags, Addr, Size);
+  CHECK_EQ(Status, ZX_OK);
+}
+
+bool ReservedMemoryFuchsia::createImpl(UNUSED uptr Addr, uptr Size,
+                                       UNUSED const char *Name, uptr Flags) {
+  const bool AllowNoMem = !!(Flags & MAP_ALLOWNOMEM);
+
+  // Reserve memory by mapping the placeholder VMO without any permission.
+  zx_status_t Status = _zx_vmar_map(_zx_vmar_root_self(), ZX_VM_ALLOW_FAULTS, 0,
+                                    getPlaceholderVmo(), 0, Size, &Base);
+  if (UNLIKELY(Status != ZX_OK)) {
+    if (AllowNoMem && IsNoMemError(Status))
+      return false;
+    dieOnError(Status, "zx_vmar_map", Size);
+  }
+
+  Capacity = Size;
+  return true;
+}
+
+void ReservedMemoryFuchsia::releaseImpl() {
+  zx_status_t Status = _zx_vmar_unmap(_zx_vmar_root_self(), Base, Capacity);
+  CHECK_EQ(Status, ZX_OK);
+}
+
+ReservedMemoryFuchsia::MemMapT ReservedMemoryFuchsia::dispatchImpl(uptr Addr,
+                                                                   uptr Size) {
+  return ReservedMemoryFuchsia::MemMapT(Addr, Size);
+}
+
+} // namespace scudo
+
+#endif // SCUDO_FUCHSIA