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1  /*
2   * Copyright (C) 2017 The Android Open Source Project
3   *
4   * Licensed under the Apache License, Version 2.0 (the "License");
5   * you may not use this file except in compliance with the License.
6   * You may obtain a copy of the License at
7   *
8   *      http://www.apache.org/licenses/LICENSE-2.0
9   *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  #include <assert.h>
18  #include <stdint.h>
19  #include <stdlib.h>
20  
21  // This library is built for all targets, including host tests, so __cfi_slowpath may not be
22  // present. But it is only used in the bionic loader tests.
23  extern "C" __attribute__((weak)) void __cfi_slowpath(uint64_t, void*);
24  
25  static size_t g_count;
26  static uint64_t g_last_type_id;
27  static void* g_last_address;
28  static void* g_last_diag;
29  
30  extern "C" {
31  
32  // Make sure the library crosses at least one kLibraryAlignment(=256KB) boundary.
33  char bss[1024 * 1024];
34  
35  // Mock a CFI-enabled library without relying on the compiler.
__cfi_check(uint64_t CallSiteTypeId,void * TargetAddr,void * Diag)36  __attribute__((aligned(4096))) void __cfi_check(uint64_t CallSiteTypeId, void* TargetAddr,
37                                                  void* Diag) {
38    ++g_count;
39    g_last_type_id = CallSiteTypeId;
40    g_last_address = TargetAddr;
41    g_last_diag = Diag;
42  }
43  
get_count()44  size_t get_count() {
45    return g_count;
46  }
47  
get_last_type_id()48  uint64_t get_last_type_id() {
49    return g_last_type_id;
50  }
51  
get_last_address()52  void* get_last_address() {
53    return g_last_address;
54  }
55  
get_last_diag()56  void* get_last_diag() {
57    return g_last_diag;
58  }
59  
get_global_address()60  void* get_global_address() {
61    return &g_count;
62  }
63  }
64  
65  // Check that CFI is set up in module constructors and destructors.
66  struct A {
check_cfi_selfA67    void check_cfi_self() {
68      g_last_type_id = 0;
69      assert(&__cfi_slowpath);
70      // CFI check for an address inside this DSO. This goes to the current module's __cfi_check,
71      // which updates g_last_type_id.
72      __cfi_slowpath(13, static_cast<void*>(&g_last_type_id));
73      assert(g_last_type_id == 13);
74      // CFI check for a libc function. This never goes into this module's __cfi_check, and must pass.
75      __cfi_slowpath(14, reinterpret_cast<void*>(&exit));
76      assert(g_last_type_id == 13);
77    }
AA78    A() {
79      check_cfi_self();
80    }
~AA81    ~A() {
82      check_cfi_self();
83    }
84  } a;
85