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/*
79 * Feature detection for gnu_inline (gnu89 extern inline semantics). Either
80 * __GNUC_STDC_INLINE__ is defined (not using gnu89 extern inline semantics,
81 * and we opt in to the gnu89 semantics), or __GNUC_STDC_INLINE__ is not
82 * defined so the gnu89 semantics are the default.
83 */
84#ifdef __GNUC_STDC_INLINE__
85# define __gnu_inline __attribute__((gnu_inline))
86#else
87# define __gnu_inline
88#endif
89
90/*
91 * Force always-inline if the user requests it so via the .config,
92 * or if gcc is too old.
93 * GCC does not warn about unused static inline functions for
94 * -Wunused-function. This turns out to avoid the need for complex #ifdef
95 * directives. Suppress the warning in clang as well by using "unused"
96 * function attribute, which is redundant but not harmful for gcc.
97 * Prefer gnu_inline, so that extern inline functions do not emit an
98 * externally visible function. This makes extern inline behave as per gnu89
99 * semantics rather than c99. This prevents multiple symbol definition errors
100 * of extern inline functions at link time.
101 * A lot of inline functions can cause havoc with function tracing.
102 */
103#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
104 !defined(CONFIG_OPTIMIZE_INLINING)
105#define inline \
106 inline __attribute__((always_inline, unused)) notrace __gnu_inline
107#else
108#define inline inline __attribute__((unused)) notrace __gnu_inline
109#endif
110
111#define __inline__ inline
112#define __inline inline
113#define __always_inline inline __attribute__((always_inline))
114#define noinline __attribute__((noinline))
115
116#define __packed __attribute__((packed))
117#define __weak __attribute__((weak))
118#define __alias(symbol) __attribute__((alias(#symbol)))
119
120#ifdef RETPOLINE
121#define __noretpoline __attribute__((indirect_branch("keep")))
122#endif
123
124/*
125 * it doesn't make sense on ARM (currently the only user of __naked)
126 * to trace naked functions because then mcount is called without
127 * stack and frame pointer being set up and there is no chance to
128 * restore the lr register to the value before mcount was called.
129 *
130 * The asm() bodies of naked functions often depend on standard calling
131 * conventions, therefore they must be noinline and noclone.
132 *
133 * GCC 4.[56] currently fail to enforce this, so we must do so ourselves.
134 * See GCC PR44290.
135 */
136#define __naked __attribute__((naked)) noinline __noclone notrace
137
138#define __noreturn __attribute__((noreturn))
139
140/*
141 * From the GCC manual:
142 *
143 * Many functions have no effects except the return value and their
144 * return value depends only on the parameters and/or global
145 * variables. Such a function can be subject to common subexpression
146 * elimination and loop optimization just as an arithmetic operator
147 * would be.
148 * [...]
149 */
150#define __pure __attribute__((pure))
151#define __aligned(x) __attribute__((aligned(x)))
152#define __aligned_largest __attribute__((aligned))
153#define __printf(a, b) __attribute__((format(printf, a, b)))
154#define __scanf(a, b) __attribute__((format(scanf, a, b)))
155#define __attribute_const__ __attribute__((__const__))
156#define __maybe_unused __attribute__((unused))
157#define __always_unused __attribute__((unused))
158#define __mode(x) __attribute__((mode(x)))
159
160#define __must_check __attribute__((warn_unused_result))
161#define __malloc __attribute__((__malloc__))
162
163#define __used __attribute__((__used__))
164#define __compiler_offsetof(a, b) \
165 __builtin_offsetof(a, b)
166
167/* Mark functions as cold. gcc will assume any path leading to a call
168 * to them will be unlikely. This means a lot of manual unlikely()s
169 * are unnecessary now for any paths leading to the usual suspects
170 * like BUG(), printk(), panic() etc. [but let's keep them for now for
171 * older compilers]
172 *
173 * Early snapshots of gcc 4.3 don't support this and we can't detect this
174 * in the preprocessor, but we can live with this because they're unreleased.
175 * Maketime probing would be overkill here.
176 *
177 * gcc also has a __attribute__((__hot__)) to move hot functions into
178 * a special section, but I don't see any sense in this right now in
179 * the kernel context
180 */
181#define __cold __attribute__((__cold__))
182
183#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
184
185#define __optimize(level) __attribute__((__optimize__(level)))
186#define __nostackprotector __optimize("no-stack-protector")
187
188#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
189
190#ifndef __CHECKER__
191#define __compiletime_warning(message) __attribute__((warning(message)))
192#define __compiletime_error(message) __attribute__((error(message)))
193
194#ifdef LATENT_ENTROPY_PLUGIN
195#define __latent_entropy __attribute__((latent_entropy))
196#endif
197#endif /* __CHECKER__ */
198
199/*
200 * calling noreturn functions, __builtin_unreachable() and __builtin_trap()
201 * confuse the stack allocation in gcc, leading to overly large stack
202 * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
203 *
204 * Adding an empty inline assembly before it works around the problem
205 */
206#define barrier_before_unreachable() asm volatile("")
207
208/*
209 * Mark a position in code as unreachable. This can be used to
210 * suppress control flow warnings after asm blocks that transfer
211 * control elsewhere.
212 *
213 * Early snapshots of gcc 4.5 don't support this and we can't detect
214 * this in the preprocessor, but we can live with this because they're
215 * unreleased. Really, we need to have autoconf for the kernel.
216 */
217#define unreachable() \
218 do { \
219 annotate_unreachable(); \
220 barrier_before_unreachable(); \
221 __builtin_unreachable(); \
222 } while (0)
223
224/* Mark a function definition as prohibited from being cloned. */
225#define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
226
227#if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__)
228#define __randomize_layout __attribute__((randomize_layout))
229#define __no_randomize_layout __attribute__((no_randomize_layout))
230/* This anon struct can add padding, so only enable it under randstruct. */
231#define randomized_struct_fields_start struct {
232#define randomized_struct_fields_end } __randomize_layout;
233#endif
234
235/*
236 * When used with Link Time Optimization, gcc can optimize away C functions or
237 * variables which are referenced only from assembly code. __visible tells the
238 * optimizer that something else uses this function or variable, thus preventing
239 * this.
240 */
241#define __visible __attribute__((externally_visible))
242
243/* gcc version specific checks */
244
245#if GCC_VERSION >= 40900 && !defined(__CHECKER__)
246/*
247 * __assume_aligned(n, k): Tell the optimizer that the returned
248 * pointer can be assumed to be k modulo n. The second argument is
249 * optional (default 0), so we use a variadic macro to make the
250 * shorthand.
251 *
252 * Beware: Do not apply this to functions which may return
253 * ERR_PTRs. Also, it is probably unwise to apply it to functions
254 * returning extra information in the low bits (but in that case the
255 * compiler should see some alignment anyway, when the return value is
256 * massaged by 'flags = ptr & 3; ptr &= ~3;').
257 */
258#define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
259#endif
260
261/*
262 * GCC 'asm goto' miscompiles certain code sequences:
263 *
264 * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
265 *
266 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
267 *
268 * (asm goto is automatically volatile - the naming reflects this.)
269 */
270#define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
271
272/*
273 * sparse (__CHECKER__) pretends to be gcc, but can't do constant
274 * folding in __builtin_bswap*() (yet), so don't set these for it.
275 */
276#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
277#define __HAVE_BUILTIN_BSWAP32__
278#define __HAVE_BUILTIN_BSWAP64__
279#if GCC_VERSION >= 40800
280#define __HAVE_BUILTIN_BSWAP16__
281#endif
282#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
283
284#if GCC_VERSION >= 70000
285#define KASAN_ABI_VERSION 5
286#elif GCC_VERSION >= 50000
287#define KASAN_ABI_VERSION 4
288#elif GCC_VERSION >= 40902
289#define KASAN_ABI_VERSION 3
290#endif
291
292#if GCC_VERSION >= 40902
293/*
294 * Tell the compiler that address safety instrumentation (KASAN)
295 * should not be applied to that function.
296 * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
297 */
298#define __no_sanitize_address __attribute__((no_sanitize_address))
299#endif
300
301#if GCC_VERSION >= 50100
302/*
303 * Mark structures as requiring designated initializers.
304 * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html
305 */
306#define __designated_init __attribute__((designated_init))
307#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
308#endif
309
310#if !defined(__noclone)
311#define __noclone /* not needed */
312#endif
313
314#if !defined(__no_sanitize_address)
315#define __no_sanitize_address
316#endif
317
318/*
319 * Turn individual warnings and errors on and off locally, depending
320 * on version.
321 */
322#define __diag_GCC(version, severity, s) \
323 __diag_GCC_ ## version(__diag_GCC_ ## severity s)
324
325/* Severity used in pragma directives */
326#define __diag_GCC_ignore ignored
327#define __diag_GCC_warn warning
328#define __diag_GCC_error error
329
330#define __diag_str1(s) #s
331#define __diag_str(s) __diag_str1(s)
332#define __diag(s) _Pragma(__diag_str(GCC diagnostic s))
333
334#if GCC_VERSION >= 80000
335#define __diag_GCC_8(s) __diag(s)
336#else
337#define __diag_GCC_8(s)
338#endif
339