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 #if GCC_VERSION < 40600
14 # error Sorry, your compiler is too old - please upgrade it.
17 /* Optimization barrier */
19 /* The "volatile" is due to gcc bugs */
20 #define barrier() __asm__ __volatile__("": : :"memory")
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
34 #define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
37 * This macro obfuscates arithmetic on a variable address so that gcc
38 * shouldn't recognize the original var, and make assumptions about it.
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.
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
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.
54 #define RELOC_HIDE(ptr, off) \
56 unsigned long __ptr; \
57 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
58 (typeof(ptr)) (__ptr + (off)); \
61 /* Make the optimizer believe the variable can be manipulated arbitrarily. */
62 #define OPTIMIZER_HIDE_VAR(var) \
63 __asm__ ("" : "=r" (var) : "0" (var))
66 * A trick to suppress uninitialized variable warning without generating any
69 #define uninitialized_var(x) x = x
72 #define __must_be_array(a) 0
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]))
79 #define __noretpoline __attribute__((indirect_branch("keep")))
82 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
84 #define __optimize(level) __attribute__((__optimize__(level)))
86 #define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
89 #define __compiletime_warning(message) __attribute__((warning(message)))
90 #define __compiletime_error(message) __attribute__((error(message)))
92 #ifdef LATENT_ENTROPY_PLUGIN
93 #define __latent_entropy __attribute__((latent_entropy))
95 #endif /* __CHECKER__ */
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
102 * Adding an empty inline assembly before it works around the problem
104 #define barrier_before_unreachable() asm volatile("")
107 * Mark a position in code as unreachable. This can be used to
108 * suppress control flow warnings after asm blocks that transfer
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.
115 #define unreachable() \
117 annotate_unreachable(); \
118 barrier_before_unreachable(); \
119 __builtin_unreachable(); \
122 /* Mark a function definition as prohibited from being cloned. */
123 #define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
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;
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
139 #define __visible __attribute__((externally_visible))
141 /* gcc version specific checks */
143 #if GCC_VERSION >= 40900 && !defined(__CHECKER__)
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
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;').
156 #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
160 * GCC 'asm goto' miscompiles certain code sequences:
162 * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
164 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
166 * (asm goto is automatically volatile - the naming reflects this.)
168 #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
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.
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__
180 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
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
190 #if GCC_VERSION >= 40902
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
196 #define __no_sanitize_address __attribute__((no_sanitize_address))
198 #define __no_sanitize_address_or_inline \
199 __no_sanitize_address __maybe_unused notrace
201 #define __no_sanitize_address_or_inline inline
205 #if GCC_VERSION >= 50100
207 * Mark structures as requiring designated initializers.
208 * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html
210 #define __designated_init __attribute__((designated_init))
211 #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
214 #if !defined(__noclone)
215 #define __noclone /* not needed */
218 #if !defined(__no_sanitize_address)
219 #define __no_sanitize_address
220 #define __no_sanitize_address_or_inline inline
224 * Turn individual warnings and errors on and off locally, depending
227 #define __diag_GCC(version, severity, s) \
228 __diag_GCC_ ## version(__diag_GCC_ ## severity s)
230 /* Severity used in pragma directives */
231 #define __diag_GCC_ignore ignored
232 #define __diag_GCC_warn warning
233 #define __diag_GCC_error error
235 #define __diag_str1(s) #s
236 #define __diag_str(s) __diag_str1(s)
237 #define __diag(s) _Pragma(__diag_str(GCC diagnostic s))
239 #if GCC_VERSION >= 80000
240 #define __diag_GCC_8(s) __diag(s)
242 #define __diag_GCC_8(s)