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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __LINUX_COMPILER_H
3#define __LINUX_COMPILER_H
4
5#include <linux/compiler_types.h>
6
7#ifndef __ASSEMBLY__
8
9#ifdef __KERNEL__
10
11/*
12 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
13 * to disable branch tracing on a per file basis.
14 */
15#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
16 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
17void ftrace_likely_update(struct ftrace_likely_data *f, int val,
18 int expect, int is_constant);
19
20#define likely_notrace(x) __builtin_expect(!!(x), 1)
21#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
22
23#define __branch_check__(x, expect, is_constant) ({ \
24 long ______r; \
25 static struct ftrace_likely_data \
26 __aligned(4) \
27 __section(_ftrace_annotated_branch) \
28 ______f = { \
29 .data.func = __func__, \
30 .data.file = __FILE__, \
31 .data.line = __LINE__, \
32 }; \
33 ______r = __builtin_expect(!!(x), expect); \
34 ftrace_likely_update(&______f, ______r, \
35 expect, is_constant); \
36 ______r; \
37 })
38
39/*
40 * Using __builtin_constant_p(x) to ignore cases where the return
41 * value is always the same. This idea is taken from a similar patch
42 * written by Daniel Walker.
43 */
44# ifndef likely
45# define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x)))
46# endif
47# ifndef unlikely
48# define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x)))
49# endif
50
51#ifdef CONFIG_PROFILE_ALL_BRANCHES
52/*
53 * "Define 'is'", Bill Clinton
54 * "Define 'if'", Steven Rostedt
55 */
56#define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
57
58#define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
59
60#define __trace_if_value(cond) ({ \
61 static struct ftrace_branch_data \
62 __aligned(4) \
63 __section(_ftrace_branch) \
64 __if_trace = { \
65 .func = __func__, \
66 .file = __FILE__, \
67 .line = __LINE__, \
68 }; \
69 (cond) ? \
70 (__if_trace.miss_hit[1]++,1) : \
71 (__if_trace.miss_hit[0]++,0); \
72})
73
74#endif /* CONFIG_PROFILE_ALL_BRANCHES */
75
76#else
77# define likely(x) __builtin_expect(!!(x), 1)
78# define unlikely(x) __builtin_expect(!!(x), 0)
79#endif
80
81/* Optimization barrier */
82#ifndef barrier
83# define barrier() __memory_barrier()
84#endif
85
86#ifndef barrier_data
87# define barrier_data(ptr) barrier()
88#endif
89
90/* workaround for GCC PR82365 if needed */
91#ifndef barrier_before_unreachable
92# define barrier_before_unreachable() do { } while (0)
93#endif
94
95/* Unreachable code */
96#ifdef CONFIG_STACK_VALIDATION
97/*
98 * These macros help objtool understand GCC code flow for unreachable code.
99 * The __COUNTER__ based labels are a hack to make each instance of the macros
100 * unique, to convince GCC not to merge duplicate inline asm statements.
101 */
102#define annotate_reachable() ({ \
103 asm volatile("%c0:\n\t" \
104 ".pushsection .discard.reachable\n\t" \
105 ".long %c0b - .\n\t" \
106 ".popsection\n\t" : : "i" (__COUNTER__)); \
107})
108#define annotate_unreachable() ({ \
109 asm volatile("%c0:\n\t" \
110 ".pushsection .discard.unreachable\n\t" \
111 ".long %c0b - .\n\t" \
112 ".popsection\n\t" : : "i" (__COUNTER__)); \
113})
114#define ASM_UNREACHABLE \
115 "999:\n\t" \
116 ".pushsection .discard.unreachable\n\t" \
117 ".long 999b - .\n\t" \
118 ".popsection\n\t"
119
120/* Annotate a C jump table to allow objtool to follow the code flow */
121#define __annotate_jump_table __section(.rodata..c_jump_table)
122
123#else
124#define annotate_reachable()
125#define annotate_unreachable()
126#define __annotate_jump_table
127#endif
128
129#ifndef ASM_UNREACHABLE
130# define ASM_UNREACHABLE
131#endif
132#ifndef unreachable
133# define unreachable() do { \
134 annotate_unreachable(); \
135 __builtin_unreachable(); \
136} while (0)
137#endif
138
139/*
140 * KENTRY - kernel entry point
141 * This can be used to annotate symbols (functions or data) that are used
142 * without their linker symbol being referenced explicitly. For example,
143 * interrupt vector handlers, or functions in the kernel image that are found
144 * programatically.
145 *
146 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
147 * are handled in their own way (with KEEP() in linker scripts).
148 *
149 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the
150 * linker script. For example an architecture could KEEP() its entire
151 * boot/exception vector code rather than annotate each function and data.
152 */
153#ifndef KENTRY
154# define KENTRY(sym) \
155 extern typeof(sym) sym; \
156 static const unsigned long __kentry_##sym \
157 __used \
158 __section("___kentry" "+" #sym ) \
159 = (unsigned long)&sym;
160#endif
161
162#ifndef RELOC_HIDE
163# define RELOC_HIDE(ptr, off) \
164 ({ unsigned long __ptr; \
165 __ptr = (unsigned long) (ptr); \
166 (typeof(ptr)) (__ptr + (off)); })
167#endif
168
169#ifndef OPTIMIZER_HIDE_VAR
170/* Make the optimizer believe the variable can be manipulated arbitrarily. */
171#define OPTIMIZER_HIDE_VAR(var) \
172 __asm__ ("" : "=r" (var) : "0" (var))
173#endif
174
175/* Not-quite-unique ID. */
176#ifndef __UNIQUE_ID
177# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
178#endif
179
180/**
181 * data_race - mark an expression as containing intentional data races
182 *
183 * This data_race() macro is useful for situations in which data races
184 * should be forgiven. One example is diagnostic code that accesses
185 * shared variables but is not a part of the core synchronization design.
186 *
187 * This macro *does not* affect normal code generation, but is a hint
188 * to tooling that data races here are to be ignored.
189 */
190#define data_race(expr) \
191({ \
192 __unqual_scalar_typeof(({ expr; })) __v = ({ \
193 __kcsan_disable_current(); \
194 expr; \
195 }); \
196 __kcsan_enable_current(); \
197 __v; \
198})
199
200#endif /* __KERNEL__ */
201
202/*
203 * Force the compiler to emit 'sym' as a symbol, so that we can reference
204 * it from inline assembler. Necessary in case 'sym' could be inlined
205 * otherwise, or eliminated entirely due to lack of references that are
206 * visible to the compiler.
207 */
208#define __ADDRESSABLE(sym) \
209 static void * __section(.discard.addressable) __used \
210 __PASTE(__addressable_##sym, __LINE__) = (void *)&sym;
211
212/**
213 * offset_to_ptr - convert a relative memory offset to an absolute pointer
214 * @off: the address of the 32-bit offset value
215 */
216static inline void *offset_to_ptr(const int *off)
217{
218 return (void *)((unsigned long)off + *off);
219}
220
221#endif /* __ASSEMBLY__ */
222
223/* &a[0] degrades to a pointer: a different type from an array */
224#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
225
226/*
227 * This is needed in functions which generate the stack canary, see
228 * arch/x86/kernel/smpboot.c::start_secondary() for an example.
229 */
230#define prevent_tail_call_optimization() mb()
231
232#include <asm/rwonce.h>
233
234#endif /* __LINUX_COMPILER_H */
1#ifndef __LINUX_COMPILER_H
2#define __LINUX_COMPILER_H
3
4#ifndef __ASSEMBLY__
5
6#ifdef __CHECKER__
7# define __user __attribute__((noderef, address_space(1)))
8# define __kernel __attribute__((address_space(0)))
9# define __safe __attribute__((safe))
10# define __force __attribute__((force))
11# define __nocast __attribute__((nocast))
12# define __iomem __attribute__((noderef, address_space(2)))
13# define __acquires(x) __attribute__((context(x,0,1)))
14# define __releases(x) __attribute__((context(x,1,0)))
15# define __acquire(x) __context__(x,1)
16# define __release(x) __context__(x,-1)
17# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
18# define __percpu __attribute__((noderef, address_space(3)))
19#ifdef CONFIG_SPARSE_RCU_POINTER
20# define __rcu __attribute__((noderef, address_space(4)))
21#else
22# define __rcu
23#endif
24extern void __chk_user_ptr(const volatile void __user *);
25extern void __chk_io_ptr(const volatile void __iomem *);
26#else
27# define __user
28# define __kernel
29# define __safe
30# define __force
31# define __nocast
32# define __iomem
33# define __chk_user_ptr(x) (void)0
34# define __chk_io_ptr(x) (void)0
35# define __builtin_warning(x, y...) (1)
36# define __acquires(x)
37# define __releases(x)
38# define __acquire(x) (void)0
39# define __release(x) (void)0
40# define __cond_lock(x,c) (c)
41# define __percpu
42# define __rcu
43#endif
44
45#ifdef __KERNEL__
46
47#ifdef __GNUC__
48#include <linux/compiler-gcc.h>
49#endif
50
51#define notrace __attribute__((no_instrument_function))
52
53/* Intel compiler defines __GNUC__. So we will overwrite implementations
54 * coming from above header files here
55 */
56#ifdef __INTEL_COMPILER
57# include <linux/compiler-intel.h>
58#endif
59
60/*
61 * Generic compiler-dependent macros required for kernel
62 * build go below this comment. Actual compiler/compiler version
63 * specific implementations come from the above header files
64 */
65
66struct ftrace_branch_data {
67 const char *func;
68 const char *file;
69 unsigned line;
70 union {
71 struct {
72 unsigned long correct;
73 unsigned long incorrect;
74 };
75 struct {
76 unsigned long miss;
77 unsigned long hit;
78 };
79 unsigned long miss_hit[2];
80 };
81};
82
83/*
84 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
85 * to disable branch tracing on a per file basis.
86 */
87#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
88 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
89void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
90
91#define likely_notrace(x) __builtin_expect(!!(x), 1)
92#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
93
94#define __branch_check__(x, expect) ({ \
95 int ______r; \
96 static struct ftrace_branch_data \
97 __attribute__((__aligned__(4))) \
98 __attribute__((section("_ftrace_annotated_branch"))) \
99 ______f = { \
100 .func = __func__, \
101 .file = __FILE__, \
102 .line = __LINE__, \
103 }; \
104 ______r = likely_notrace(x); \
105 ftrace_likely_update(&______f, ______r, expect); \
106 ______r; \
107 })
108
109/*
110 * Using __builtin_constant_p(x) to ignore cases where the return
111 * value is always the same. This idea is taken from a similar patch
112 * written by Daniel Walker.
113 */
114# ifndef likely
115# define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
116# endif
117# ifndef unlikely
118# define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
119# endif
120
121#ifdef CONFIG_PROFILE_ALL_BRANCHES
122/*
123 * "Define 'is'", Bill Clinton
124 * "Define 'if'", Steven Rostedt
125 */
126#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
127#define __trace_if(cond) \
128 if (__builtin_constant_p((cond)) ? !!(cond) : \
129 ({ \
130 int ______r; \
131 static struct ftrace_branch_data \
132 __attribute__((__aligned__(4))) \
133 __attribute__((section("_ftrace_branch"))) \
134 ______f = { \
135 .func = __func__, \
136 .file = __FILE__, \
137 .line = __LINE__, \
138 }; \
139 ______r = !!(cond); \
140 ______f.miss_hit[______r]++; \
141 ______r; \
142 }))
143#endif /* CONFIG_PROFILE_ALL_BRANCHES */
144
145#else
146# define likely(x) __builtin_expect(!!(x), 1)
147# define unlikely(x) __builtin_expect(!!(x), 0)
148#endif
149
150/* Optimization barrier */
151#ifndef barrier
152# define barrier() __memory_barrier()
153#endif
154
155/* Unreachable code */
156#ifndef unreachable
157# define unreachable() do { } while (1)
158#endif
159
160#ifndef RELOC_HIDE
161# define RELOC_HIDE(ptr, off) \
162 ({ unsigned long __ptr; \
163 __ptr = (unsigned long) (ptr); \
164 (typeof(ptr)) (__ptr + (off)); })
165#endif
166
167#endif /* __KERNEL__ */
168
169#endif /* __ASSEMBLY__ */
170
171#ifdef __KERNEL__
172/*
173 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
174 * warning for each use, in hopes of speeding the functions removal.
175 * Usage is:
176 * int __deprecated foo(void)
177 */
178#ifndef __deprecated
179# define __deprecated /* unimplemented */
180#endif
181
182#ifdef MODULE
183#define __deprecated_for_modules __deprecated
184#else
185#define __deprecated_for_modules
186#endif
187
188#ifndef __must_check
189#define __must_check
190#endif
191
192#ifndef CONFIG_ENABLE_MUST_CHECK
193#undef __must_check
194#define __must_check
195#endif
196#ifndef CONFIG_ENABLE_WARN_DEPRECATED
197#undef __deprecated
198#undef __deprecated_for_modules
199#define __deprecated
200#define __deprecated_for_modules
201#endif
202
203/*
204 * Allow us to avoid 'defined but not used' warnings on functions and data,
205 * as well as force them to be emitted to the assembly file.
206 *
207 * As of gcc 3.4, static functions that are not marked with attribute((used))
208 * may be elided from the assembly file. As of gcc 3.4, static data not so
209 * marked will not be elided, but this may change in a future gcc version.
210 *
211 * NOTE: Because distributions shipped with a backported unit-at-a-time
212 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
213 * for gcc >=3.3 instead of 3.4.
214 *
215 * In prior versions of gcc, such functions and data would be emitted, but
216 * would be warned about except with attribute((unused)).
217 *
218 * Mark functions that are referenced only in inline assembly as __used so
219 * the code is emitted even though it appears to be unreferenced.
220 */
221#ifndef __used
222# define __used /* unimplemented */
223#endif
224
225#ifndef __maybe_unused
226# define __maybe_unused /* unimplemented */
227#endif
228
229#ifndef __always_unused
230# define __always_unused /* unimplemented */
231#endif
232
233#ifndef noinline
234#define noinline
235#endif
236
237/*
238 * Rather then using noinline to prevent stack consumption, use
239 * noinline_for_stack instead. For documentation reasons.
240 */
241#define noinline_for_stack noinline
242
243#ifndef __always_inline
244#define __always_inline inline
245#endif
246
247#endif /* __KERNEL__ */
248
249/*
250 * From the GCC manual:
251 *
252 * Many functions do not examine any values except their arguments,
253 * and have no effects except the return value. Basically this is
254 * just slightly more strict class than the `pure' attribute above,
255 * since function is not allowed to read global memory.
256 *
257 * Note that a function that has pointer arguments and examines the
258 * data pointed to must _not_ be declared `const'. Likewise, a
259 * function that calls a non-`const' function usually must not be
260 * `const'. It does not make sense for a `const' function to return
261 * `void'.
262 */
263#ifndef __attribute_const__
264# define __attribute_const__ /* unimplemented */
265#endif
266
267/*
268 * Tell gcc if a function is cold. The compiler will assume any path
269 * directly leading to the call is unlikely.
270 */
271
272#ifndef __cold
273#define __cold
274#endif
275
276/* Simple shorthand for a section definition */
277#ifndef __section
278# define __section(S) __attribute__ ((__section__(#S)))
279#endif
280
281/* Are two types/vars the same type (ignoring qualifiers)? */
282#ifndef __same_type
283# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
284#endif
285
286/* Compile time object size, -1 for unknown */
287#ifndef __compiletime_object_size
288# define __compiletime_object_size(obj) -1
289#endif
290#ifndef __compiletime_warning
291# define __compiletime_warning(message)
292#endif
293#ifndef __compiletime_error
294# define __compiletime_error(message)
295#endif
296#ifndef __linktime_error
297# define __linktime_error(message)
298#endif
299/*
300 * Prevent the compiler from merging or refetching accesses. The compiler
301 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
302 * but only when the compiler is aware of some particular ordering. One way
303 * to make the compiler aware of ordering is to put the two invocations of
304 * ACCESS_ONCE() in different C statements.
305 *
306 * This macro does absolutely -nothing- to prevent the CPU from reordering,
307 * merging, or refetching absolutely anything at any time. Its main intended
308 * use is to mediate communication between process-level code and irq/NMI
309 * handlers, all running on the same CPU.
310 */
311#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
312
313#endif /* __LINUX_COMPILER_H */