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."
7 * Common definitions for all gcc versions go here.
9 #define GCC_VERSION (__GNUC__ * 10000 \
10 + __GNUC_MINOR__ * 100 \
11 + __GNUC_PATCHLEVEL__)
13 /* Optimization barrier */
15 /* The "volatile" is due to gcc bugs */
16 #define barrier() __asm__ __volatile__("": : :"memory")
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
30 #define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
33 * This macro obfuscates arithmetic on a variable address so that gcc
34 * shouldn't recognize the original var, and make assumptions about it.
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.
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
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.
50 #define RELOC_HIDE(ptr, off) \
52 unsigned long __ptr; \
53 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
54 (typeof(ptr)) (__ptr + (off)); \
57 /* Make the optimizer believe the variable can be manipulated arbitrarily. */
58 #define OPTIMIZER_HIDE_VAR(var) \
59 __asm__ ("" : "=r" (var) : "0" (var))
62 #define __must_be_array(a) 0
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]))
69 * Feature detection for gnu_inline (gnu89 extern inline semantics). Either
70 * __GNUC_STDC_INLINE__ is defined (not using gnu89 extern inline semantics,
71 * and we opt in to the gnu89 semantics), or __GNUC_STDC_INLINE__ is not
72 * defined so the gnu89 semantics are the default.
74 #ifdef __GNUC_STDC_INLINE__
75 # define __gnu_inline __attribute__((gnu_inline))
81 * Force always-inline if the user requests it so via the .config,
82 * or if gcc is too old.
83 * GCC does not warn about unused static inline functions for
84 * -Wunused-function. This turns out to avoid the need for complex #ifdef
85 * directives. Suppress the warning in clang as well by using "unused"
86 * function attribute, which is redundant but not harmful for gcc.
87 * Prefer gnu_inline, so that extern inline functions do not emit an
88 * externally visible function. This makes extern inline behave as per gnu89
89 * semantics rather than c99. This prevents multiple symbol definition errors
90 * of extern inline functions at link time.
91 * A lot of inline functions can cause havoc with function tracing.
93 #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
94 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
96 inline __attribute__((always_inline, unused)) notrace __gnu_inline
98 #define inline inline __attribute__((unused)) notrace __gnu_inline
101 #define __inline__ inline
102 #define __inline inline
103 #define __always_inline inline __attribute__((always_inline))
104 #define noinline __attribute__((noinline))
106 #define __deprecated __attribute__((deprecated))
107 #define __packed __attribute__((packed))
108 #define __weak __attribute__((weak))
109 #define __alias(symbol) __attribute__((alias(#symbol)))
111 #ifdef CONFIG_RETPOLINE
112 #define __noretpoline __attribute__((indirect_branch("keep")))
116 * it doesn't make sense on ARM (currently the only user of __naked)
117 * to trace naked functions because then mcount is called without
118 * stack and frame pointer being set up and there is no chance to
119 * restore the lr register to the value before mcount was called.
121 * The asm() bodies of naked functions often depend on standard calling
122 * conventions, therefore they must be noinline and noclone.
124 * GCC 4.[56] currently fail to enforce this, so we must do so ourselves.
127 #define __naked __attribute__((naked)) noinline __noclone notrace
129 #define __noreturn __attribute__((noreturn))
132 * From the GCC manual:
134 * Many functions have no effects except the return value and their
135 * return value depends only on the parameters and/or global
136 * variables. Such a function can be subject to common subexpression
137 * elimination and loop optimization just as an arithmetic operator
141 #define __pure __attribute__((pure))
142 #define __aligned(x) __attribute__((aligned(x)))
143 #define __aligned_largest __attribute__((aligned))
144 #define __printf(a, b) __attribute__((format(printf, a, b)))
145 #define __scanf(a, b) __attribute__((format(scanf, a, b)))
146 #define __attribute_const__ __attribute__((__const__))
147 #define __maybe_unused __attribute__((unused))
148 #define __always_unused __attribute__((unused))
149 #define __mode(x) __attribute__((mode(x)))
151 /* gcc version specific checks */
153 #if GCC_VERSION < 30200
154 # error Sorry, your compiler is too old - please upgrade it.
155 #elif defined(CONFIG_ARM64) && GCC_VERSION < 50100 && !defined(__clang__)
157 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
158 * https://lore.kernel.org/r/20210107111841.GN1551@shell.armlinux.org.uk
160 # error Sorry, your version of GCC is too old - please use 5.1 or newer.
163 #if GCC_VERSION < 30300
164 # define __used __attribute__((__unused__))
166 # define __used __attribute__((__used__))
169 #ifdef CONFIG_GCOV_KERNEL
170 # if GCC_VERSION < 30400
171 # error "GCOV profiling support for gcc versions below 3.4 not included"
172 # endif /* __GNUC_MINOR__ */
173 #endif /* CONFIG_GCOV_KERNEL */
175 #if GCC_VERSION >= 30400
176 #define __must_check __attribute__((warn_unused_result))
177 #define __malloc __attribute__((__malloc__))
180 #if GCC_VERSION >= 40000
182 /* GCC 4.1.[01] miscompiles __weak */
184 # if GCC_VERSION >= 40100 && GCC_VERSION <= 40101
185 # error Your version of gcc miscompiles the __weak directive
189 #define __used __attribute__((__used__))
190 #define __compiler_offsetof(a, b) \
191 __builtin_offsetof(a, b)
193 #if GCC_VERSION >= 40100
194 # define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
197 #if GCC_VERSION >= 40300
198 /* Mark functions as cold. gcc will assume any path leading to a call
199 * to them will be unlikely. This means a lot of manual unlikely()s
200 * are unnecessary now for any paths leading to the usual suspects
201 * like BUG(), printk(), panic() etc. [but let's keep them for now for
204 * Early snapshots of gcc 4.3 don't support this and we can't detect this
205 * in the preprocessor, but we can live with this because they're unreleased.
206 * Maketime probing would be overkill here.
208 * gcc also has a __attribute__((__hot__)) to move hot functions into
209 * a special section, but I don't see any sense in this right now in
212 #define __cold __attribute__((__cold__))
214 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
217 # define __compiletime_warning(message) __attribute__((warning(message)))
218 # define __compiletime_error(message) __attribute__((error(message)))
219 #endif /* __CHECKER__ */
220 #endif /* GCC_VERSION >= 40300 */
222 #if GCC_VERSION >= 40400
223 #define __optimize(level) __attribute__((__optimize__(level)))
224 #define __nostackprotector __optimize("no-stack-protector")
225 #endif /* GCC_VERSION >= 40400 */
227 #if GCC_VERSION >= 40500
230 #ifdef LATENT_ENTROPY_PLUGIN
231 #define __latent_entropy __attribute__((latent_entropy))
236 * calling noreturn functions, __builtin_unreachable() and __builtin_trap()
237 * confuse the stack allocation in gcc, leading to overly large stack
238 * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
240 * Adding an empty inline assembly before it works around the problem
242 #define barrier_before_unreachable() asm volatile("")
245 * Mark a position in code as unreachable. This can be used to
246 * suppress control flow warnings after asm blocks that transfer
249 * Early snapshots of gcc 4.5 don't support this and we can't detect
250 * this in the preprocessor, but we can live with this because they're
251 * unreleased. Really, we need to have autoconf for the kernel.
253 #define unreachable() \
255 annotate_unreachable(); \
256 barrier_before_unreachable(); \
257 __builtin_unreachable(); \
260 /* Mark a function definition as prohibited from being cloned. */
261 #define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
263 #ifdef RANDSTRUCT_PLUGIN
264 #define __randomize_layout __attribute__((randomize_layout))
265 #define __no_randomize_layout __attribute__((no_randomize_layout))
266 /* This anon struct can add padding, so only enable it under randstruct. */
267 #define randomized_struct_fields_start struct {
268 #define randomized_struct_fields_end } __randomize_layout;
271 #endif /* GCC_VERSION >= 40500 */
273 #if GCC_VERSION >= 40600
276 * When used with Link Time Optimization, gcc can optimize away C functions or
277 * variables which are referenced only from assembly code. __visible tells the
278 * optimizer that something else uses this function or variable, thus preventing
281 #define __visible __attribute__((externally_visible))
283 #endif /* GCC_VERSION >= 40600 */
286 #if GCC_VERSION >= 40900 && !defined(__CHECKER__)
288 * __assume_aligned(n, k): Tell the optimizer that the returned
289 * pointer can be assumed to be k modulo n. The second argument is
290 * optional (default 0), so we use a variadic macro to make the
293 * Beware: Do not apply this to functions which may return
294 * ERR_PTRs. Also, it is probably unwise to apply it to functions
295 * returning extra information in the low bits (but in that case the
296 * compiler should see some alignment anyway, when the return value is
297 * massaged by 'flags = ptr & 3; ptr &= ~3;').
299 #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
303 * GCC 'asm goto' miscompiles certain code sequences:
305 * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
307 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
309 * (asm goto is automatically volatile - the naming reflects this.)
311 #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
314 * sparse (__CHECKER__) pretends to be gcc, but can't do constant
315 * folding in __builtin_bswap*() (yet), so don't set these for it.
317 #if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
318 #if GCC_VERSION >= 40400
319 #define __HAVE_BUILTIN_BSWAP32__
320 #define __HAVE_BUILTIN_BSWAP64__
322 #if GCC_VERSION >= 40800
323 #define __HAVE_BUILTIN_BSWAP16__
325 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
327 #if GCC_VERSION >= 70000
328 #define KASAN_ABI_VERSION 5
329 #elif GCC_VERSION >= 50000
330 #define KASAN_ABI_VERSION 4
331 #elif GCC_VERSION >= 40902
332 #define KASAN_ABI_VERSION 3
335 #if GCC_VERSION >= 40902
337 * Tell the compiler that address safety instrumentation (KASAN)
338 * should not be applied to that function.
339 * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
341 #define __no_sanitize_address __attribute__((no_sanitize_address))
344 #if GCC_VERSION >= 50100
346 * Mark structures as requiring designated initializers.
347 * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html
349 #define __designated_init __attribute__((designated_init))
352 #if GCC_VERSION >= 90100
353 #define __copy(symbol) __attribute__((__copy__(symbol)))
356 #endif /* gcc version >= 40000 specific checks */
358 #if !defined(__noclone)
359 #define __noclone /* not needed */
362 #if !defined(__no_sanitize_address)
363 #define __no_sanitize_address
367 * A trick to suppress uninitialized variable warning without generating any
370 #define uninitialized_var(x) x = x
372 #if GCC_VERSION >= 50100
373 #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1