Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 */