Linux kernel mirror (for testing)
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linux
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __LINUX_COMPILER_TYPES_H
3#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
4#endif
5
6/*
7 * Common definitions for all gcc versions go here.
8 */
9#define GCC_VERSION (__GNUC__ * 10000 \
10 + __GNUC_MINOR__ * 100 \
11 + __GNUC_PATCHLEVEL__)
12
13#if GCC_VERSION < 40600
14# error Sorry, your compiler is too old - please upgrade it.
15#endif
16
17/* Optimization barrier */
18
19/* The "volatile" is due to gcc bugs */
20#define barrier() __asm__ __volatile__("": : :"memory")
21/*
22 * This version is i.e. to prevent dead stores elimination on @ptr
23 * where gcc and llvm may behave differently when otherwise using
24 * normal barrier(): while gcc behavior gets along with a normal
25 * barrier(), llvm needs an explicit input variable to be assumed
26 * clobbered. The issue is as follows: while the inline asm might
27 * access any memory it wants, the compiler could have fit all of
28 * @ptr into memory registers instead, and since @ptr never escaped
29 * from that, it proved that the inline asm wasn't touching any of
30 * it. This version works well with both compilers, i.e. we're telling
31 * the compiler that the inline asm absolutely may see the contents
32 * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
33 */
34#define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
35
36/*
37 * This macro obfuscates arithmetic on a variable address so that gcc
38 * shouldn't recognize the original var, and make assumptions about it.
39 *
40 * This is needed because the C standard makes it undefined to do
41 * pointer arithmetic on "objects" outside their boundaries and the
42 * gcc optimizers assume this is the case. In particular they
43 * assume such arithmetic does not wrap.
44 *
45 * A miscompilation has been observed because of this on PPC.
46 * To work around it we hide the relationship of the pointer and the object
47 * using this macro.
48 *
49 * Versions of the ppc64 compiler before 4.1 had a bug where use of
50 * RELOC_HIDE could trash r30. The bug can be worked around by changing
51 * the inline assembly constraint from =g to =r, in this particular
52 * case either is valid.
53 */
54#define RELOC_HIDE(ptr, off) \
55({ \
56 unsigned long __ptr; \
57 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
58 (typeof(ptr)) (__ptr + (off)); \
59})
60
61/* Make the optimizer believe the variable can be manipulated arbitrarily. */
62#define OPTIMIZER_HIDE_VAR(var) \
63 __asm__ ("" : "=r" (var) : "0" (var))
64
65/*
66 * A trick to suppress uninitialized variable warning without generating any
67 * code
68 */
69#define uninitialized_var(x) x = x
70
71#ifdef __CHECKER__
72#define __must_be_array(a) 0
73#else
74/* &a[0] degrades to a pointer: a different type from an array */
75#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
76#endif
77
78#ifdef RETPOLINE
79#define __noretpoline __attribute__((indirect_branch("keep")))
80#endif
81
82#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
83
84#define __optimize(level) __attribute__((__optimize__(level)))
85
86#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
87
88#ifndef __CHECKER__
89#define __compiletime_warning(message) __attribute__((warning(message)))
90#define __compiletime_error(message) __attribute__((error(message)))
91
92#ifdef LATENT_ENTROPY_PLUGIN
93#define __latent_entropy __attribute__((latent_entropy))
94#endif
95#endif /* __CHECKER__ */
96
97/*
98 * calling noreturn functions, __builtin_unreachable() and __builtin_trap()
99 * confuse the stack allocation in gcc, leading to overly large stack
100 * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
101 *
102 * Adding an empty inline assembly before it works around the problem
103 */
104#define barrier_before_unreachable() asm volatile("")
105
106/*
107 * Mark a position in code as unreachable. This can be used to
108 * suppress control flow warnings after asm blocks that transfer
109 * control elsewhere.
110 *
111 * Early snapshots of gcc 4.5 don't support this and we can't detect
112 * this in the preprocessor, but we can live with this because they're
113 * unreleased. Really, we need to have autoconf for the kernel.
114 */
115#define unreachable() \
116 do { \
117 annotate_unreachable(); \
118 barrier_before_unreachable(); \
119 __builtin_unreachable(); \
120 } while (0)
121
122/* Mark a function definition as prohibited from being cloned. */
123#define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
124
125#if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__)
126#define __randomize_layout __attribute__((randomize_layout))
127#define __no_randomize_layout __attribute__((no_randomize_layout))
128/* This anon struct can add padding, so only enable it under randstruct. */
129#define randomized_struct_fields_start struct {
130#define randomized_struct_fields_end } __randomize_layout;
131#endif
132
133/*
134 * When used with Link Time Optimization, gcc can optimize away C functions or
135 * variables which are referenced only from assembly code. __visible tells the
136 * optimizer that something else uses this function or variable, thus preventing
137 * this.
138 */
139#define __visible __attribute__((externally_visible))
140
141/* gcc version specific checks */
142
143#if GCC_VERSION >= 40900 && !defined(__CHECKER__)
144/*
145 * __assume_aligned(n, k): Tell the optimizer that the returned
146 * pointer can be assumed to be k modulo n. The second argument is
147 * optional (default 0), so we use a variadic macro to make the
148 * shorthand.
149 *
150 * Beware: Do not apply this to functions which may return
151 * ERR_PTRs. Also, it is probably unwise to apply it to functions
152 * returning extra information in the low bits (but in that case the
153 * compiler should see some alignment anyway, when the return value is
154 * massaged by 'flags = ptr & 3; ptr &= ~3;').
155 */
156#define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
157#endif
158
159/*
160 * GCC 'asm goto' miscompiles certain code sequences:
161 *
162 * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
163 *
164 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
165 *
166 * (asm goto is automatically volatile - the naming reflects this.)
167 */
168#define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
169
170/*
171 * sparse (__CHECKER__) pretends to be gcc, but can't do constant
172 * folding in __builtin_bswap*() (yet), so don't set these for it.
173 */
174#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
175#define __HAVE_BUILTIN_BSWAP32__
176#define __HAVE_BUILTIN_BSWAP64__
177#if GCC_VERSION >= 40800
178#define __HAVE_BUILTIN_BSWAP16__
179#endif
180#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
181
182#if GCC_VERSION >= 70000
183#define KASAN_ABI_VERSION 5
184#elif GCC_VERSION >= 50000
185#define KASAN_ABI_VERSION 4
186#elif GCC_VERSION >= 40902
187#define KASAN_ABI_VERSION 3
188#endif
189
190#if GCC_VERSION >= 40902
191/*
192 * Tell the compiler that address safety instrumentation (KASAN)
193 * should not be applied to that function.
194 * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
195 */
196#define __no_sanitize_address __attribute__((no_sanitize_address))
197#endif
198
199#if GCC_VERSION >= 50100
200/*
201 * Mark structures as requiring designated initializers.
202 * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html
203 */
204#define __designated_init __attribute__((designated_init))
205#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
206#endif
207
208#if !defined(__noclone)
209#define __noclone /* not needed */
210#endif
211
212#if !defined(__no_sanitize_address)
213#define __no_sanitize_address
214#endif
215
216/*
217 * Turn individual warnings and errors on and off locally, depending
218 * on version.
219 */
220#define __diag_GCC(version, severity, s) \
221 __diag_GCC_ ## version(__diag_GCC_ ## severity s)
222
223/* Severity used in pragma directives */
224#define __diag_GCC_ignore ignored
225#define __diag_GCC_warn warning
226#define __diag_GCC_error error
227
228#define __diag_str1(s) #s
229#define __diag_str(s) __diag_str1(s)
230#define __diag(s) _Pragma(__diag_str(GCC diagnostic s))
231
232#if GCC_VERSION >= 80000
233#define __diag_GCC_8(s) __diag(s)
234#else
235#define __diag_GCC_8(s)
236#endif