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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."
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 * 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.
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
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
88 #define __always_inline inline __attribute__((always_inline))
89 #define noinline __attribute__((noinline))
91 #define __deprecated __attribute__((deprecated))
92 #define __packed __attribute__((packed))
93 #define __weak __attribute__((weak))
94 #define __alias(symbol) __attribute__((alias(#symbol)))
97 #define __noretpoline __attribute__((indirect_branch("keep")))
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.
106 * The asm() bodies of naked functions often depend on standard calling
107 * conventions, therefore they must be noinline and noclone.
109 * GCC 4.[56] currently fail to enforce this, so we must do so ourselves.
112 #define __naked __attribute__((naked)) noinline __noclone notrace
114 #define __noreturn __attribute__((noreturn))
117 * From the GCC manual:
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
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)))
136 /* gcc version specific checks */
138 #if GCC_VERSION < 30200
139 # error Sorry, your compiler is too old - please upgrade it.
142 #if GCC_VERSION < 30300
143 # define __used __attribute__((__unused__))
145 # define __used __attribute__((__used__))
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 */
154 #if GCC_VERSION >= 30400
155 #define __must_check __attribute__((warn_unused_result))
156 #define __malloc __attribute__((__malloc__))
159 #if GCC_VERSION >= 40000
161 /* GCC 4.1.[01] miscompiles __weak */
163 # if GCC_VERSION >= 40100 && GCC_VERSION <= 40101
164 # error Your version of gcc miscompiles the __weak directive
168 #define __used __attribute__((__used__))
169 #define __compiler_offsetof(a, b) \
170 __builtin_offsetof(a, b)
172 #if GCC_VERSION >= 40100
173 # define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
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
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.
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
191 #define __cold __attribute__((__cold__))
193 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
196 # define __compiletime_warning(message) __attribute__((warning(message)))
197 # define __compiletime_error(message) __attribute__((error(message)))
198 #endif /* __CHECKER__ */
199 #endif /* GCC_VERSION >= 40300 */
201 #if GCC_VERSION >= 40400
202 #define __optimize(level) __attribute__((__optimize__(level)))
203 #define __nostackprotector __optimize("no-stack-protector")
204 #endif /* GCC_VERSION >= 40400 */
206 #if GCC_VERSION >= 40500
209 #ifdef LATENT_ENTROPY_PLUGIN
210 #define __latent_entropy __attribute__((latent_entropy))
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
219 * Adding an empty inline assembly before it works around the problem
221 #define barrier_before_unreachable() asm volatile("")
224 * Mark a position in code as unreachable. This can be used to
225 * suppress control flow warnings after asm blocks that transfer
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.
232 #define unreachable() \
234 annotate_unreachable(); \
235 barrier_before_unreachable(); \
236 __builtin_unreachable(); \
239 /* Mark a function definition as prohibited from being cloned. */
240 #define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
242 #if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__)
243 #define __randomize_layout __attribute__((randomize_layout))
244 #define __no_randomize_layout __attribute__((no_randomize_layout))
247 #endif /* GCC_VERSION >= 40500 */
249 #if GCC_VERSION >= 40600
252 * When used with Link Time Optimization, gcc can optimize away C functions or
253 * variables which are referenced only from assembly code. __visible tells the
254 * optimizer that something else uses this function or variable, thus preventing
257 #define __visible __attribute__((externally_visible))
260 * RANDSTRUCT_PLUGIN wants to use an anonymous struct, but it is only
261 * possible since GCC 4.6. To provide as much build testing coverage
262 * as possible, this is used for all GCC 4.6+ builds, and not just on
263 * RANDSTRUCT_PLUGIN builds.
265 #define randomized_struct_fields_start struct {
266 #define randomized_struct_fields_end } __randomize_layout;
268 #endif /* GCC_VERSION >= 40600 */
271 #if GCC_VERSION >= 40900 && !defined(__CHECKER__)
273 * __assume_aligned(n, k): Tell the optimizer that the returned
274 * pointer can be assumed to be k modulo n. The second argument is
275 * optional (default 0), so we use a variadic macro to make the
278 * Beware: Do not apply this to functions which may return
279 * ERR_PTRs. Also, it is probably unwise to apply it to functions
280 * returning extra information in the low bits (but in that case the
281 * compiler should see some alignment anyway, when the return value is
282 * massaged by 'flags = ptr & 3; ptr &= ~3;').
284 #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
288 * GCC 'asm goto' miscompiles certain code sequences:
290 * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
292 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
294 * (asm goto is automatically volatile - the naming reflects this.)
296 #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
299 * sparse (__CHECKER__) pretends to be gcc, but can't do constant
300 * folding in __builtin_bswap*() (yet), so don't set these for it.
302 #if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
303 #if GCC_VERSION >= 40400
304 #define __HAVE_BUILTIN_BSWAP32__
305 #define __HAVE_BUILTIN_BSWAP64__
307 #if GCC_VERSION >= 40800
308 #define __HAVE_BUILTIN_BSWAP16__
310 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
312 #if GCC_VERSION >= 70000
313 #define KASAN_ABI_VERSION 5
314 #elif GCC_VERSION >= 50000
315 #define KASAN_ABI_VERSION 4
316 #elif GCC_VERSION >= 40902
317 #define KASAN_ABI_VERSION 3
320 #if GCC_VERSION >= 40902
322 * Tell the compiler that address safety instrumentation (KASAN)
323 * should not be applied to that function.
324 * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
326 #define __no_sanitize_address __attribute__((no_sanitize_address))
329 #if GCC_VERSION >= 50100
331 * Mark structures as requiring designated initializers.
332 * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html
334 #define __designated_init __attribute__((designated_init))
337 #endif /* gcc version >= 40000 specific checks */
339 #if !defined(__noclone)
340 #define __noclone /* not needed */
343 #if !defined(__no_sanitize_address)
344 #define __no_sanitize_address
348 * A trick to suppress uninitialized variable warning without generating any
351 #define uninitialized_var(x) x = x