[GWP-ASan] Fuchsia specific mapping & utilities functions

This CL introduces the Fuchsia versions of the existing platform
specific functions.

For Fuchsia, we need to track the VMAR (https://fuchsia.dev/fuchsia-src/reference/kernel_objects/vm_address_region)
of the Guarded Pool mapping, and for this purpose I added some platform
specific data structure that remains empty on POSIX platforms.

`getThreadID` is not super useful for Fuchsia so it's just left as a
stub for now.

While testing the changes in my Fuchsia tree, I realized that
`guarded_pool_allocator_tls.h` should have closed the namespace before
including `GWP_ASAN_PLATFORM_TLS_HEADER`, otherwise drama ensues.

This was tested in g3, upstream LLVM, and Fuchsia (with local changes).

Differential Revision: https://reviews.llvm.org/D90483

compiler-rt/lib/gwp_asan/CMakeLists.txt

@@ -22,6 +22,8 @@ set(GWP_ASAN_HEADERS
   mutex.h
   options.h
   options.inc
+  platform_specific/guarded_pool_allocator_fuchsia.h
+  platform_specific/guarded_pool_allocator_posix.h
   platform_specific/guarded_pool_allocator_tls.h
   platform_specific/mutex_fuchsia.h
   platform_specific/mutex_posix.h

compiler-rt/lib/gwp_asan/guarded_pool_allocator.h

@@ -13,6 +13,8 @@
 #include "gwp_asan/definitions.h"
 #include "gwp_asan/mutex.h"
 #include "gwp_asan/options.h"
+#include "gwp_asan/platform_specific/guarded_pool_allocator_fuchsia.h"
+#include "gwp_asan/platform_specific/guarded_pool_allocator_posix.h"
 #include "gwp_asan/platform_specific/guarded_pool_allocator_tls.h"
 #include "gwp_asan/stack_trace_compressor.h"
 
@@ -207,6 +209,9 @@ private:
   // the sample rate.
   uint32_t AdjustedSampleRatePlusOne = 0;
 
+  // Additional platform specific data structure for the guarded pool mapping.
+  PlatformSpecificMapData GuardedPagePoolPlatformData = {};
+
   class ScopedRecursiveGuard {
   public:
     ScopedRecursiveGuard() { getThreadLocals()->RecursiveGuard = true; }

compiler-rt/lib/gwp_asan/platform_specific/common_fuchsia.cpp

@@ -0,0 +1,15 @@
+//===-- common_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 "gwp_asan/common.h"
+
+namespace gwp_asan {
+// This is only used for AllocationTrace.ThreadID and allocation traces are not
+// yet supported on Fuchsia.
+uint64_t getThreadID() { return kInvalidThreadID; }
+} // namespace gwp_asan

compiler-rt/lib/gwp_asan/platform_specific/guarded_pool_allocator_fuchsia.cpp

@@ -0,0 +1,103 @@
+//===-- guarded_pool_allocator_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 "gwp_asan/guarded_pool_allocator.h"
+#include "gwp_asan/utilities.h"
+
+#include <assert.h>
+#include <stdint.h>
+#include <string.h>
+#include <zircon/limits.h>
+#include <zircon/process.h>
+#include <zircon/syscalls.h>
+
+namespace gwp_asan {
+void GuardedPoolAllocator::initPRNG() {
+  _zx_cprng_draw(&getThreadLocals()->RandomState, sizeof(uint32_t));
+}
+
+void *GuardedPoolAllocator::map(size_t Size, const char *Name) const {
+  assert((Size % State.PageSize) == 0);
+  zx_handle_t Vmo;
+  zx_status_t Status = _zx_vmo_create(Size, 0, &Vmo);
+  Check(Status == ZX_OK, "Failed to create Vmo");
+  _zx_object_set_property(Vmo, ZX_PROP_NAME, Name, strlen(Name));
+  zx_vaddr_t Addr;
+  Status = _zx_vmar_map(_zx_vmar_root_self(),
+                        ZX_VM_PERM_READ | ZX_VM_PERM_WRITE | ZX_VM_ALLOW_FAULTS,
+                        0, Vmo, 0, Size, &Addr);
+  Check(Status == ZX_OK, "Vmo mapping failed");
+  _zx_handle_close(Vmo);
+  return reinterpret_cast<void *>(Addr);
+}
+
+void GuardedPoolAllocator::unmap(void *Ptr, size_t Size) const {
+  assert((reinterpret_cast<uintptr_t>(Ptr) % State.PageSize) == 0);
+  assert((Size % State.PageSize) == 0);
+  zx_status_t Status = _zx_vmar_unmap(_zx_vmar_root_self(),
+                                      reinterpret_cast<zx_vaddr_t>(Ptr), Size);
+  Check(Status == ZX_OK, "Vmo unmapping failed");
+}
+
+void *GuardedPoolAllocator::reserveGuardedPool(size_t Size) {
+  assert((Size % State.PageSize) == 0);
+  zx_vaddr_t Addr;
+  const zx_status_t Status = _zx_vmar_allocate(
+      _zx_vmar_root_self(),
+      ZX_VM_CAN_MAP_READ | ZX_VM_CAN_MAP_WRITE | ZX_VM_CAN_MAP_SPECIFIC, 0,
+      Size, &GuardedPagePoolPlatformData.Vmar, &Addr);
+  Check(Status == ZX_OK, "Failed to reserve guarded pool allocator memory");
+  _zx_object_set_property(GuardedPagePoolPlatformData.Vmar, ZX_PROP_NAME,
+                          kGwpAsanGuardPageName, strlen(kGwpAsanGuardPageName));
+  return reinterpret_cast<void *>(Addr);
+}
+
+void GuardedPoolAllocator::unreserveGuardedPool() {
+  const zx_handle_t Vmar = GuardedPagePoolPlatformData.Vmar;
+  assert(Vmar != ZX_HANDLE_INVALID && Vmar != _zx_vmar_root_self());
+  Check(_zx_vmar_destroy(Vmar) == ZX_OK, "Failed to destroy a vmar");
+  Check(_zx_handle_close(Vmar) == ZX_OK, "Failed to close a vmar");
+  GuardedPagePoolPlatformData.Vmar = ZX_HANDLE_INVALID;
+}
+
+void GuardedPoolAllocator::allocateInGuardedPool(void *Ptr, size_t Size) const {
+  assert((reinterpret_cast<uintptr_t>(Ptr) % State.PageSize) == 0);
+  assert((Size % State.PageSize) == 0);
+  zx_handle_t Vmo;
+  zx_status_t Status = _zx_vmo_create(Size, 0, &Vmo);
+  Check(Status == ZX_OK, "Failed to create vmo");
+  _zx_object_set_property(Vmo, ZX_PROP_NAME, kGwpAsanAliveSlotName,
+                          strlen(kGwpAsanAliveSlotName));
+  const zx_handle_t Vmar = GuardedPagePoolPlatformData.Vmar;
+  assert(Vmar != ZX_HANDLE_INVALID && Vmar != _zx_vmar_root_self());
+  const size_t Offset =
+      reinterpret_cast<uintptr_t>(Ptr) - State.GuardedPagePool;
+  zx_vaddr_t P;
+  Status = _zx_vmar_map(Vmar,
+                        ZX_VM_PERM_READ | ZX_VM_PERM_WRITE |
+                            ZX_VM_ALLOW_FAULTS | ZX_VM_SPECIFIC,
+                        Offset, Vmo, 0, Size, &P);
+  Check(Status == ZX_OK, "Vmo mapping failed");
+  _zx_handle_close(Vmo);
+}
+
+void GuardedPoolAllocator::deallocateInGuardedPool(void *Ptr,
+                                                   size_t Size) const {
+  assert((reinterpret_cast<uintptr_t>(Ptr) % State.PageSize) == 0);
+  assert((Size % State.PageSize) == 0);
+  const zx_handle_t Vmar = GuardedPagePoolPlatformData.Vmar;
+  assert(Vmar != ZX_HANDLE_INVALID && Vmar != _zx_vmar_root_self());
+  const zx_status_t Status =
+      _zx_vmar_unmap(Vmar, reinterpret_cast<zx_vaddr_t>(Ptr), Size);
+  Check(Status == ZX_OK, "Vmar unmapping failed");
+}
+
+size_t GuardedPoolAllocator::getPlatformPageSize() { return ZX_PAGE_SIZE; }
+
+void GuardedPoolAllocator::installAtFork() {}
+} // namespace gwp_asan

compiler-rt/lib/gwp_asan/platform_specific/guarded_pool_allocator_fuchsia.h

@@ -0,0 +1,22 @@
+//===-- guarded_pool_allocator_fuchsia.h ------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#if defined(__Fuchsia__)
+#ifndef GWP_ASAN_GUARDED_POOL_ALLOCATOR_FUCHSIA_H_
+#define GWP_ASAN_GUARDED_POOL_ALLOCATOR_FUCHSIA_H_
+
+#include <zircon/types.h>
+
+namespace gwp_asan {
+struct PlatformSpecificMapData {
+  zx_handle_t Vmar;
+};
+} // namespace gwp_asan
+
+#endif // GWP_ASAN_GUARDED_POOL_ALLOCATOR_FUCHSIA_H_
+#endif // defined(__Fuchsia__)

compiler-rt/lib/gwp_asan/platform_specific/guarded_pool_allocator_posix.h

@@ -0,0 +1,18 @@
+//===-- guarded_pool_allocator_posix.h --------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#if defined(__unix__)
+#ifndef GWP_ASAN_GUARDED_POOL_ALLOCATOR_POSIX_H_
+#define GWP_ASAN_GUARDED_POOL_ALLOCATOR_POSIX_H_
+
+namespace gwp_asan {
+struct PlatformSpecificMapData {};
+} // namespace gwp_asan
+
+#endif // GWP_ASAN_GUARDED_POOL_ALLOCATOR_POSIX_H_
+#endif // defined(__unix__)

compiler-rt/lib/gwp_asan/platform_specific/guarded_pool_allocator_tls.h

@@ -39,15 +39,17 @@ struct ThreadLocalPackedVariables {
 };
 static_assert(sizeof(ThreadLocalPackedVariables) == sizeof(uint64_t),
               "thread local data does not fit in a uint64_t");
+} // namespace gwp_asan
 
 #ifdef GWP_ASAN_PLATFORM_TLS_HEADER
 #include GWP_ASAN_PLATFORM_TLS_HEADER
 #else
+namespace gwp_asan {
 inline ThreadLocalPackedVariables *getThreadLocals() {
   alignas(8) static GWP_ASAN_TLS_INITIAL_EXEC ThreadLocalPackedVariables Locals;
   return &Locals;
 }
-#endif
 } // namespace gwp_asan
+#endif // GWP_ASAN_PLATFORM_TLS_HEADER
 
 #endif // GWP_ASAN_GUARDED_POOL_ALLOCATOR_TLS_H_

compiler-rt/lib/gwp_asan/platform_specific/utilities_fuchsia.cpp

@@ -0,0 +1,19 @@
+//===-- utilities_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 "gwp_asan/utilities.h"
+
+#include <string.h>
+#include <zircon/sanitizer.h>
+
+namespace gwp_asan {
+void die(const char *Message) {
+  __sanitizer_log_write(Message, strlen(Message));
+  __builtin_trap();
+}
+} // namespace gwp_asan