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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/* Optimization barrier */
14
15/* The "volatile" is due to gcc bugs */
16#define barrier() __asm__ __volatile__("": : :"memory")
17/*
18 * This version is i.e. to prevent dead stores elimination on @ptr
19 * where gcc and llvm may behave differently when otherwise using
20 * normal barrier(): while gcc behavior gets along with a normal
21 * barrier(), llvm needs an explicit input variable to be assumed
22 * clobbered. The issue is as follows: while the inline asm might
23 * access any memory it wants, the compiler could have fit all of
24 * @ptr into memory registers instead, and since @ptr never escaped
25 * from that, it proved that the inline asm wasn't touching any of
26 * it. This version works well with both compilers, i.e. we're telling
27 * the compiler that the inline asm absolutely may see the contents
28 * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
29 */
30#define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
31
32/*
33 * This macro obfuscates arithmetic on a variable address so that gcc
34 * shouldn't recognize the original var, and make assumptions about it.
35 *
36 * This is needed because the C standard makes it undefined to do
37 * pointer arithmetic on "objects" outside their boundaries and the
38 * gcc optimizers assume this is the case. In particular they
39 * assume such arithmetic does not wrap.
40 *
41 * A miscompilation has been observed because of this on PPC.
42 * To work around it we hide the relationship of the pointer and the object
43 * using this macro.
44 *
45 * Versions of the ppc64 compiler before 4.1 had a bug where use of
46 * RELOC_HIDE could trash r30. The bug can be worked around by changing
47 * the inline assembly constraint from =g to =r, in this particular
48 * case either is valid.
49 */
50#define RELOC_HIDE(ptr, off) \
51({ \
52 unsigned long __ptr; \
53 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
54 (typeof(ptr)) (__ptr + (off)); \
55})
56
57/* Make the optimizer believe the variable can be manipulated arbitrarily. */
58#define OPTIMIZER_HIDE_VAR(var) \
59 __asm__ ("" : "=r" (var) : "0" (var))
60
61#ifdef __CHECKER__
62#define __must_be_array(a) 0
63#else
64/* &a[0] degrades to a pointer: a different type from an array */
65#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
66#endif
67
68/*
69 * Force always-inline if the user requests it so via the .config,
70 * or if gcc is too old.
71 * GCC does not warn about unused static inline functions for
72 * -Wunused-function. This turns out to avoid the need for complex #ifdef
73 * directives. Suppress the warning in clang as well by using "unused"
74 * function attribute, which is redundant but not harmful for gcc.
75 */
76#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
77 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
78#define inline inline __attribute__((always_inline,unused)) notrace
79#define __inline__ __inline__ __attribute__((always_inline,unused)) notrace
80#define __inline __inline __attribute__((always_inline,unused)) notrace
81#else
82/* A lot of inline functions can cause havoc with function tracing */
83#define inline inline __attribute__((unused)) notrace
84#define __inline__ __inline__ __attribute__((unused)) notrace
85#define __inline __inline __attribute__((unused)) notrace
86#endif
87
88#define __always_inline inline __attribute__((always_inline))
89#define noinline __attribute__((noinline))
90
91#define __deprecated __attribute__((deprecated))
92#define __packed __attribute__((packed))
93#define __weak __attribute__((weak))
94#define __alias(symbol) __attribute__((alias(#symbol)))
95
96#ifdef RETPOLINE
97#define __noretpoline __attribute__((indirect_branch("keep")))
98#endif
99
100/*
101 * it doesn't make sense on ARM (currently the only user of __naked)
102 * to trace naked functions because then mcount is called without
103 * stack and frame pointer being set up and there is no chance to
104 * restore the lr register to the value before mcount was called.
105 *
106 * The asm() bodies of naked functions often depend on standard calling
107 * conventions, therefore they must be noinline and noclone.
108 *
109 * GCC 4.[56] currently fail to enforce this, so we must do so ourselves.
110 * See GCC PR44290.
111 */
112#define __naked __attribute__((naked)) noinline __noclone notrace
113
114#define __noreturn __attribute__((noreturn))
115
116/*
117 * From the GCC manual:
118 *
119 * Many functions have no effects except the return value and their
120 * return value depends only on the parameters and/or global
121 * variables. Such a function can be subject to common subexpression
122 * elimination and loop optimization just as an arithmetic operator
123 * would be.
124 * [...]
125 */
126#define __pure __attribute__((pure))
127#define __aligned(x) __attribute__((aligned(x)))
128#define __aligned_largest __attribute__((aligned))
129#define __printf(a, b) __attribute__((format(printf, a, b)))
130#define __scanf(a, b) __attribute__((format(scanf, a, b)))
131#define __attribute_const__ __attribute__((__const__))
132#define __maybe_unused __attribute__((unused))
133#define __always_unused __attribute__((unused))
134#define __mode(x) __attribute__((mode(x)))
135
136/* gcc version specific checks */
137
138#if GCC_VERSION < 30200
139# error Sorry, your compiler is too old - please upgrade it.
140#endif
141
142#if GCC_VERSION < 30300
143# define __used __attribute__((__unused__))
144#else
145# define __used __attribute__((__used__))
146#endif
147
148#ifdef CONFIG_GCOV_KERNEL
149# if GCC_VERSION < 30400
150# error "GCOV profiling support for gcc versions below 3.4 not included"
151# endif /* __GNUC_MINOR__ */
152#endif /* CONFIG_GCOV_KERNEL */
153
154#if GCC_VERSION >= 30400
155#define __must_check __attribute__((warn_unused_result))
156#define __malloc __attribute__((__malloc__))
157#endif
158
159#if GCC_VERSION >= 40000
160
161/* GCC 4.1.[01] miscompiles __weak */
162#ifdef __KERNEL__
163# if GCC_VERSION >= 40100 && GCC_VERSION <= 40101
164# error Your version of gcc miscompiles the __weak directive
165# endif
166#endif
167
168#define __used __attribute__((__used__))
169#define __compiler_offsetof(a, b) \
170 __builtin_offsetof(a, b)
171
172#if GCC_VERSION >= 40100
173# define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
174#endif
175
176#if GCC_VERSION >= 40300
177/* Mark functions as cold. gcc will assume any path leading to a call
178 * to them will be unlikely. This means a lot of manual unlikely()s
179 * are unnecessary now for any paths leading to the usual suspects
180 * like BUG(), printk(), panic() etc. [but let's keep them for now for
181 * older compilers]
182 *
183 * Early snapshots of gcc 4.3 don't support this and we can't detect this
184 * in the preprocessor, but we can live with this because they're unreleased.
185 * Maketime probing would be overkill here.
186 *
187 * gcc also has a __attribute__((__hot__)) to move hot functions into
188 * a special section, but I don't see any sense in this right now in
189 * the kernel context
190 */
191#define __cold __attribute__((__cold__))
192
193#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
194
195#ifndef __CHECKER__
196# define __compiletime_warning(message) __attribute__((warning(message)))
197# define __compiletime_error(message) __attribute__((error(message)))
198#endif /* __CHECKER__ */
199#endif /* GCC_VERSION >= 40300 */
200
201#if GCC_VERSION >= 40400
202#define __optimize(level) __attribute__((__optimize__(level)))
203#define __nostackprotector __optimize("no-stack-protector")
204#endif /* GCC_VERSION >= 40400 */
205
206#if GCC_VERSION >= 40500
207
208#ifndef __CHECKER__
209#ifdef LATENT_ENTROPY_PLUGIN
210#define __latent_entropy __attribute__((latent_entropy))
211#endif
212#endif
213
214/*
215 * calling noreturn functions, __builtin_unreachable() and __builtin_trap()
216 * confuse the stack allocation in gcc, leading to overly large stack
217 * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
218 *
219 * Adding an empty inline assembly before it works around the problem
220 */
221#define barrier_before_unreachable() asm volatile("")
222
223/*
224 * Mark a position in code as unreachable. This can be used to
225 * suppress control flow warnings after asm blocks that transfer
226 * control elsewhere.
227 *
228 * Early snapshots of gcc 4.5 don't support this and we can't detect
229 * this in the preprocessor, but we can live with this because they're
230 * unreleased. Really, we need to have autoconf for the kernel.
231 */
232#define unreachable() \
233 do { \
234 annotate_unreachable(); \
235 barrier_before_unreachable(); \
236 __builtin_unreachable(); \
237 } while (0)
238
239/* Mark a function definition as prohibited from being cloned. */
240#define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
241
242#if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__)
243#define __randomize_layout __attribute__((randomize_layout))
244#define __no_randomize_layout __attribute__((no_randomize_layout))
245/* This anon struct can add padding, so only enable it under randstruct. */
246#define randomized_struct_fields_start struct {
247#define randomized_struct_fields_end } __randomize_layout;
248#endif
249
250#endif /* GCC_VERSION >= 40500 */
251
252#if GCC_VERSION >= 40600
253
254/*
255 * When used with Link Time Optimization, gcc can optimize away C functions or
256 * variables which are referenced only from assembly code. __visible tells the
257 * optimizer that something else uses this function or variable, thus preventing
258 * this.
259 */
260#define __visible __attribute__((externally_visible))
261
262#endif /* GCC_VERSION >= 40600 */
263
264
265#if GCC_VERSION >= 40900 && !defined(__CHECKER__)
266/*
267 * __assume_aligned(n, k): Tell the optimizer that the returned
268 * pointer can be assumed to be k modulo n. The second argument is
269 * optional (default 0), so we use a variadic macro to make the
270 * shorthand.
271 *
272 * Beware: Do not apply this to functions which may return
273 * ERR_PTRs. Also, it is probably unwise to apply it to functions
274 * returning extra information in the low bits (but in that case the
275 * compiler should see some alignment anyway, when the return value is
276 * massaged by 'flags = ptr & 3; ptr &= ~3;').
277 */
278#define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
279#endif
280
281/*
282 * GCC 'asm goto' miscompiles certain code sequences:
283 *
284 * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
285 *
286 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
287 *
288 * (asm goto is automatically volatile - the naming reflects this.)
289 */
290#define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
291
292/*
293 * sparse (__CHECKER__) pretends to be gcc, but can't do constant
294 * folding in __builtin_bswap*() (yet), so don't set these for it.
295 */
296#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
297#if GCC_VERSION >= 40400
298#define __HAVE_BUILTIN_BSWAP32__
299#define __HAVE_BUILTIN_BSWAP64__
300#endif
301#if GCC_VERSION >= 40800
302#define __HAVE_BUILTIN_BSWAP16__
303#endif
304#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
305
306#if GCC_VERSION >= 70000
307#define KASAN_ABI_VERSION 5
308#elif GCC_VERSION >= 50000
309#define KASAN_ABI_VERSION 4
310#elif GCC_VERSION >= 40902
311#define KASAN_ABI_VERSION 3
312#endif
313
314#if GCC_VERSION >= 40902
315/*
316 * Tell the compiler that address safety instrumentation (KASAN)
317 * should not be applied to that function.
318 * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
319 */
320#define __no_sanitize_address __attribute__((no_sanitize_address))
321#endif
322
323#if GCC_VERSION >= 50100
324/*
325 * Mark structures as requiring designated initializers.
326 * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html
327 */
328#define __designated_init __attribute__((designated_init))
329#endif
330
331#endif /* gcc version >= 40000 specific checks */
332
333#if !defined(__noclone)
334#define __noclone /* not needed */
335#endif
336
337#if !defined(__no_sanitize_address)
338#define __no_sanitize_address
339#endif
340
341/*
342 * A trick to suppress uninitialized variable warning without generating any
343 * code
344 */
345#define uninitialized_var(x) x = x