1 /*
2 * Copyright (C) 2010 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 #pragma once
18
19 #include <stddef.h>
20 #include <stdint.h>
21
22 #define BIONIC_DISALLOW_COPY_AND_ASSIGN(TypeName) \
23 TypeName(const TypeName&) = delete; \
24 void operator=(const TypeName&) = delete
25
26 #define BIONIC_DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
27 TypeName() = delete; \
28 BIONIC_DISALLOW_COPY_AND_ASSIGN(TypeName)
29
30 #define BIONIC_ROUND_UP_POWER_OF_2(value) \
31 ((sizeof(value) == 8) \
32 ? (1UL << (64 - __builtin_clzl(static_cast<unsigned long>(value)))) \
33 : (1UL << (32 - __builtin_clz(static_cast<unsigned int>(value)))))
34
35 #if defined(__arm__)
36 #define BIONIC_STOP_UNWIND asm volatile(".cfi_undefined r14")
37 #elif defined(__aarch64__)
38 #define BIONIC_STOP_UNWIND asm volatile(".cfi_undefined x30")
39 #elif defined(__i386__)
40 #define BIONIC_STOP_UNWIND asm volatile(".cfi_undefined \%eip")
41 #elif defined(__riscv)
42 #define BIONIC_STOP_UNWIND asm volatile(".cfi_undefined ra")
43 #elif defined(__x86_64__)
44 #define BIONIC_STOP_UNWIND asm volatile(".cfi_undefined \%rip")
45 #endif
46
47 // The arraysize(arr) macro returns the # of elements in an array arr.
48 // The expression is a compile-time constant, and therefore can be
49 // used in defining new arrays, for example. If you use arraysize on
50 // a pointer by mistake, you will get a compile-time error.
51 //
52 // One caveat is that arraysize() doesn't accept any array of an
53 // anonymous type or a type defined inside a function.
54 //
55 // This template function declaration is used in defining arraysize.
56 // Note that the function doesn't need an implementation, as we only
57 // use its type.
58 template <typename T, size_t N>
59 char (&ArraySizeHelper(T (&array)[N]))[N]; // NOLINT(readability/casting)
60
61 #define arraysize(array) (sizeof(ArraySizeHelper(array)))
62
63 // Used to inform clang's -Wimplicit-fallthrough that a fallthrough is intended. There's no way to
64 // silence (or enable, apparently) -Wimplicit-fallthrough in C yet.
65 #ifdef __cplusplus
66 #define __BIONIC_FALLTHROUGH [[clang::fallthrough]]
67 #else
68 #define __BIONIC_FALLTHROUGH
69 #endif
70
untag_address(uintptr_t p)71 static inline uintptr_t untag_address(uintptr_t p) {
72 #if defined(__aarch64__)
73 return p & ((1ULL << 56) - 1);
74 #else
75 return p;
76 #endif
77 }
78
79 template <typename T>
untag_address(T * _Nonnull p)80 static inline T* _Nonnull untag_address(T* _Nonnull p) {
81 return reinterpret_cast<T*>(untag_address(reinterpret_cast<uintptr_t>(p)));
82 }
83
84 // MTE globals protects internal and external global variables. One of the main
85 // things that MTE globals does is force all global variable accesses to go
86 // through the GOT. In the linker though, some global variables are accessed (or
87 // address-taken) prior to relocations being processed. Because relocations
88 // haven't run yet, the GOT entry hasn't been populated, and this leads to
89 // crashes. Thus, any globals used by the linker prior to relocation should be
90 // annotated with this attribute, which suppresses tagging of this global
91 // variable, restoring the pc-relative address computation.
92 //
93 // A way to find global variables that need this attribute is to build the
94 // linker/libc with `SANITIZE_TARGET=memtag_globals`, push them onto a device
95 // (it doesn't have to be MTE capable), and then run an executable using
96 // LD_LIBRARY_PATH and using the linker in interpreter mode (e.g.
97 // `LD_LIBRARY_PATH=/data/tmp/ /data/tmp/linker64 /data/tmp/my_binary`). A
98 // good heuristic is that the global variable is in a file that should be
99 // compiled with `-ffreestanding` (but there are global variables there that
100 // don't need this attribute).
101 #if __has_feature(memtag_globals)
102 #define BIONIC_USED_BEFORE_LINKER_RELOCATES __attribute__((no_sanitize("memtag")))
103 #else // __has_feature(memtag_globals)
104 #define BIONIC_USED_BEFORE_LINKER_RELOCATES
105 #endif // __has_feature(memtag_globals)
106