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Tom Rini67f51b42020-05-14 08:30:06 -04001/* SPDX-License-Identifier: GPL-2.0 */
Graeme Russ95ffaba2010-04-24 00:05:49 +10002#ifndef __LINUX_COMPILER_H
3#define __LINUX_COMPILER_H
4
Tom Rini67f51b42020-05-14 08:30:06 -04005#include <linux/compiler_types.h>
6
Graeme Russ95ffaba2010-04-24 00:05:49 +10007#ifndef __ASSEMBLY__
8
Graeme Russ95ffaba2010-04-24 00:05:49 +10009#ifdef __KERNEL__
10
Graeme Russ95ffaba2010-04-24 00:05:49 +100011/*
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__)
Tom Rini67f51b42020-05-14 08:30:06 -040017void ftrace_likely_update(struct ftrace_likely_data *f, int val,
18 int expect, int is_constant);
Graeme Russ95ffaba2010-04-24 00:05:49 +100019
20#define likely_notrace(x) __builtin_expect(!!(x), 1)
21#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
22
Tom Rini67f51b42020-05-14 08:30:06 -040023#define __branch_check__(x, expect, is_constant) ({ \
24 long ______r; \
25 static struct ftrace_likely_data \
26 __aligned(4) \
Marek Behún236f2ec2021-05-20 13:23:52 +020027 __section("_ftrace_annotated_branch") \
Graeme Russ95ffaba2010-04-24 00:05:49 +100028 ______f = { \
Tom Rini67f51b42020-05-14 08:30:06 -040029 .data.func = __func__, \
30 .data.file = __FILE__, \
31 .data.line = __LINE__, \
Graeme Russ95ffaba2010-04-24 00:05:49 +100032 }; \
Tom Rini67f51b42020-05-14 08:30:06 -040033 ______r = __builtin_expect(!!(x), expect); \
34 ftrace_likely_update(&______f, ______r, \
35 expect, is_constant); \
Graeme Russ95ffaba2010-04-24 00:05:49 +100036 ______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
Tom Rini67f51b42020-05-14 08:30:06 -040045# define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x)))
Graeme Russ95ffaba2010-04-24 00:05:49 +100046# endif
47# ifndef unlikely
Tom Rini67f51b42020-05-14 08:30:06 -040048# define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x)))
Graeme Russ95ffaba2010-04-24 00:05:49 +100049# endif
50
51#ifdef CONFIG_PROFILE_ALL_BRANCHES
52/*
53 * "Define 'is'", Bill Clinton
54 * "Define 'if'", Steven Rostedt
55 */
Tom Rini67f51b42020-05-14 08:30:06 -040056#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) \
Marek Behún236f2ec2021-05-20 13:23:52 +020063 __section("_ftrace_branch") \
Tom Rini67f51b42020-05-14 08:30:06 -040064 __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
Graeme Russ95ffaba2010-04-24 00:05:49 +100074#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
Tom Rini9b2c2822016-02-29 11:34:15 -050086#ifndef barrier_data
87# define barrier_data(ptr) barrier()
88#endif
89
Tom Rini67f51b42020-05-14 08:30:06 -040090/* workaround for GCC PR82365 if needed */
91#ifndef barrier_before_unreachable
92# define barrier_before_unreachable() do { } while (0)
93#endif
94
Graeme Russ95ffaba2010-04-24 00:05:49 +100095/* Unreachable code */
Tom Rini67f51b42020-05-14 08:30:06 -040096#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 */
Marek Behún236f2ec2021-05-20 13:23:52 +0200121#define __annotate_jump_table __section(".rodata..c_jump_table")
Tom Rini67f51b42020-05-14 08:30:06 -0400122
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
Graeme Russ95ffaba2010-04-24 00:05:49 +1000132#ifndef unreachable
Tom Rini67f51b42020-05-14 08:30:06 -0400133# 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;
Graeme Russ95ffaba2010-04-24 00:05:49 +1000160#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
Masahiro Yamadafb8ffd72014-09-04 02:40:58 +0900169#ifndef OPTIMIZER_HIDE_VAR
Tom Rini67f51b42020-05-14 08:30:06 -0400170/* Make the optimizer believe the variable can be manipulated arbitrarily. */
171#define OPTIMIZER_HIDE_VAR(var) \
172 __asm__ ("" : "=r" (var) : "0" (var))
Masahiro Yamadafb8ffd72014-09-04 02:40:58 +0900173#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
Tom Rini9b2c2822016-02-29 11:34:15 -0500180#include <linux/types.h>
181
182#define __READ_ONCE_SIZE \
183({ \
184 switch (size) { \
185 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \
186 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \
187 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \
188 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \
189 default: \
190 barrier(); \
191 __builtin_memcpy((void *)res, (const void *)p, size); \
192 barrier(); \
193 } \
194})
195
196static __always_inline
197void __read_once_size(const volatile void *p, void *res, int size)
198{
199 __READ_ONCE_SIZE;
200}
201
202#ifdef CONFIG_KASAN
203/*
Tom Rini67f51b42020-05-14 08:30:06 -0400204 * We can't declare function 'inline' because __no_sanitize_address confilcts
Tom Rini9b2c2822016-02-29 11:34:15 -0500205 * with inlining. Attempt to inline it may cause a build failure.
Wolfgang Denk0cf207e2021-09-27 17:42:39 +0200206 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
Tom Rini9b2c2822016-02-29 11:34:15 -0500207 * '__maybe_unused' allows us to avoid defined-but-not-used warnings.
208 */
Tom Rini67f51b42020-05-14 08:30:06 -0400209# define __no_kasan_or_inline __no_sanitize_address notrace __maybe_unused
Tom Rini9b2c2822016-02-29 11:34:15 -0500210#else
Tom Rini67f51b42020-05-14 08:30:06 -0400211# define __no_kasan_or_inline __always_inline
212#endif
213
214static __no_kasan_or_inline
Tom Rini9b2c2822016-02-29 11:34:15 -0500215void __read_once_size_nocheck(const volatile void *p, void *res, int size)
216{
217 __READ_ONCE_SIZE;
218}
Tom Rini9b2c2822016-02-29 11:34:15 -0500219
220static __always_inline void __write_once_size(volatile void *p, void *res, int size)
221{
222 switch (size) {
223 case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
224 case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
225 case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
226 case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
227 default:
228 barrier();
229 __builtin_memcpy((void *)p, (const void *)res, size);
230 barrier();
231 }
232}
233
234/*
235 * Prevent the compiler from merging or refetching reads or writes. The
236 * compiler is also forbidden from reordering successive instances of
Tom Rini67f51b42020-05-14 08:30:06 -0400237 * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some
238 * particular ordering. One way to make the compiler aware of ordering is to
239 * put the two invocations of READ_ONCE or WRITE_ONCE in different C
240 * statements.
Tom Rini9b2c2822016-02-29 11:34:15 -0500241 *
Tom Rini67f51b42020-05-14 08:30:06 -0400242 * These two macros will also work on aggregate data types like structs or
243 * unions. If the size of the accessed data type exceeds the word size of
244 * the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will
245 * fall back to memcpy(). There's at least two memcpy()s: one for the
246 * __builtin_memcpy() and then one for the macro doing the copy of variable
247 * - '__u' allocated on the stack.
Tom Rini9b2c2822016-02-29 11:34:15 -0500248 *
249 * Their two major use cases are: (1) Mediating communication between
250 * process-level code and irq/NMI handlers, all running on the same CPU,
Tom Rini67f51b42020-05-14 08:30:06 -0400251 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
Tom Rini9b2c2822016-02-29 11:34:15 -0500252 * mutilate accesses that either do not require ordering or that interact
253 * with an explicit memory barrier or atomic instruction that provides the
254 * required ordering.
255 */
256
257#define __READ_ONCE(x, check) \
258({ \
259 union { typeof(x) __val; char __c[1]; } __u; \
260 if (check) \
261 __read_once_size(&(x), __u.__c, sizeof(x)); \
262 else \
263 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
264 __u.__val; \
265})
266#define READ_ONCE(x) __READ_ONCE(x, 1)
267
268/*
269 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
270 * to hide memory access from KASAN.
271 */
272#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
273
Tom Rini67f51b42020-05-14 08:30:06 -0400274static __no_kasan_or_inline
275unsigned long read_word_at_a_time(const void *addr)
276{
277 return *(unsigned long *)addr;
278}
279
Tom Rini9b2c2822016-02-29 11:34:15 -0500280#define WRITE_ONCE(x, val) \
281({ \
282 union { typeof(x) __val; char __c[1]; } __u = \
283 { .__val = (__force typeof(x)) (val) }; \
284 __write_once_size(&(x), __u.__c, sizeof(x)); \
285 __u.__val; \
286})
287
Graeme Russ95ffaba2010-04-24 00:05:49 +1000288#endif /* __KERNEL__ */
289
Tom Rini67f51b42020-05-14 08:30:06 -0400290/*
291 * Force the compiler to emit 'sym' as a symbol, so that we can reference
292 * it from inline assembler. Necessary in case 'sym' could be inlined
293 * otherwise, or eliminated entirely due to lack of references that are
294 * visible to the compiler.
295 */
296#define __ADDRESSABLE(sym) \
Marek Behún236f2ec2021-05-20 13:23:52 +0200297 static void * __section(".discard.addressable") __used \
Marek Behún998929b2021-05-20 13:23:53 +0200298 __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym;
Tom Rini67f51b42020-05-14 08:30:06 -0400299
300/**
301 * offset_to_ptr - convert a relative memory offset to an absolute pointer
302 * @off: the address of the 32-bit offset value
303 */
304static inline void *offset_to_ptr(const int *off)
305{
306 return (void *)((unsigned long)off + *off);
307}
308
Graeme Russ95ffaba2010-04-24 00:05:49 +1000309#endif /* __ASSEMBLY__ */
310
Graeme Russ95ffaba2010-04-24 00:05:49 +1000311/* Compile time object size, -1 for unknown */
312#ifndef __compiletime_object_size
313# define __compiletime_object_size(obj) -1
314#endif
315#ifndef __compiletime_warning
316# define __compiletime_warning(message)
317#endif
318#ifndef __compiletime_error
319# define __compiletime_error(message)
Masahiro Yamadafb8ffd72014-09-04 02:40:58 +0900320#endif
321
Masahiro Yamada059a4802017-09-16 14:10:44 +0900322#ifdef __OPTIMIZE__
323# define __compiletime_assert(condition, msg, prefix, suffix) \
Masahiro Yamadafb8ffd72014-09-04 02:40:58 +0900324 do { \
Masahiro Yamadafb8ffd72014-09-04 02:40:58 +0900325 extern void prefix ## suffix(void) __compiletime_error(msg); \
Tom Rini67f51b42020-05-14 08:30:06 -0400326 if (!(condition)) \
Masahiro Yamadafb8ffd72014-09-04 02:40:58 +0900327 prefix ## suffix(); \
Masahiro Yamadafb8ffd72014-09-04 02:40:58 +0900328 } while (0)
Masahiro Yamada059a4802017-09-16 14:10:44 +0900329#else
330# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
331#endif
Masahiro Yamadafb8ffd72014-09-04 02:40:58 +0900332
333#define _compiletime_assert(condition, msg, prefix, suffix) \
334 __compiletime_assert(condition, msg, prefix, suffix)
335
336/**
337 * compiletime_assert - break build and emit msg if condition is false
338 * @condition: a compile-time constant condition to check
339 * @msg: a message to emit if condition is false
340 *
341 * In tradition of POSIX assert, this macro will break the build if the
342 * supplied condition is *false*, emitting the supplied error message if the
343 * compiler has support to do so.
344 */
345#define compiletime_assert(condition, msg) \
Tom Rini67f51b42020-05-14 08:30:06 -0400346 _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
Masahiro Yamadafb8ffd72014-09-04 02:40:58 +0900347
348#define compiletime_assert_atomic_type(t) \
349 compiletime_assert(__native_word(t), \
350 "Need native word sized stores/loads for atomicity.")
Graeme Russ95ffaba2010-04-24 00:05:49 +1000351
Tom Rini67f51b42020-05-14 08:30:06 -0400352/* &a[0] degrades to a pointer: a different type from an array */
353#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
Tom Rini9b2c2822016-02-29 11:34:15 -0500354
Graeme Russ95ffaba2010-04-24 00:05:49 +1000355#endif /* __LINUX_COMPILER_H */