| 1 |
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| 2 | #ifndef __LINUX_COMPILER_H
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| 3 | #define __LINUX_COMPILER_H
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| 4 |
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| 5 | #include <linux/compiler_types.h>
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| 6 |
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| 7 | #ifndef __ASSEMBLY__
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| 8 |
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| 9 | #ifdef __KERNEL__
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| 10 |
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| 11 | |
| 12 | * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
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| 13 | * to disable branch tracing on a per file basis.
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| 14 |
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| 15 | void ftrace_likely_update(struct ftrace_likely_data *f, int val,
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| 16 | int expect, int is_constant);
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| 17 | #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
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| 18 | && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
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| 19 | #define likely_notrace(x) __builtin_expect(!!(x), 1)
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| 20 | #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
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| 21 |
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| 22 | #define __branch_check__(x, expect, is_constant) ({ \
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| 23 | long ______r; \
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| 24 | static struct ftrace_likely_data \
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| 25 | __aligned(4) \
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| 26 | __section("_ftrace_annotated_branch") \
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| 27 | ______f = { \
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| 28 | .data.func = __func__, \
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| 29 | .data.file = __FILE__, \
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| 30 | .data.line = __LINE__, \
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| 31 | }; \
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| 32 | ______r = __builtin_expect(!!(x), expect); \
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| 33 | ftrace_likely_update(&______f, ______r, \
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| 34 | expect, is_constant); \
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| 35 | ______r; \
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| 36 | })
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| 37 |
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| 38 | |
| 39 | * Using __builtin_constant_p(x) to ignore cases where the return
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| 40 | * value is always the same. This idea is taken from a similar patch
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| 41 | * written by Daniel Walker.
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| 42 |
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| 43 | # ifndef likely
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| 44 | # define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x)))
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| 45 | # endif
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| 46 | # ifndef unlikely
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| 47 | # define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x)))
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| 48 | # endif
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| 49 |
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| 50 | #ifdef CONFIG_PROFILE_ALL_BRANCHES
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| 51 | |
| 52 | * "Define 'is'", Bill Clinton
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| 53 | * "Define 'if'", Steven Rostedt
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| 54 |
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| 55 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
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| 56 |
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| 57 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
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| 58 |
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| 59 | #define __trace_if_value(cond) ({ \
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| 60 | static struct ftrace_branch_data \
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| 61 | __aligned(4) \
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| 62 | __section("_ftrace_branch") \
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| 63 | __if_trace = { \
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| 64 | .func = __func__, \
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| 65 | .file = __FILE__, \
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| 66 | .line = __LINE__, \
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| 67 | }; \
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| 68 | (cond) ? \
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| 69 | (__if_trace.miss_hit[1]++,1) : \
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| 70 | (__if_trace.miss_hit[0]++,0); \
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| 71 | })
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| 72 |
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| 73 | #endif
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| 74 |
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| 75 | #else
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| 76 | # define likely(x) __builtin_expect(!!(x), 1)
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| 77 | # define unlikely(x) __builtin_expect(!!(x), 0)
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| 78 | # define likely_notrace(x) likely(x)
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| 79 | # define unlikely_notrace(x) unlikely(x)
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| 80 | #endif
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| 81 |
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| 82 |
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| 83 | #ifndef barrier
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| 84 |
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| 85 | # define barrier() __asm__ __volatile__("": : :"memory")
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| 86 | #endif
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| 87 |
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| 88 | #ifndef barrier_data
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| 89 | |
| 90 | * This version is i.e. to prevent dead stores elimination on @ptr
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| 91 | * where gcc and llvm may behave differently when otherwise using
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| 92 | * normal barrier(): while gcc behavior gets along with a normal
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| 93 | * barrier(), llvm needs an explicit input variable to be assumed
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| 94 | * clobbered. The issue is as follows: while the inline asm might
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| 95 | * access any memory it wants, the compiler could have fit all of
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| 96 | * @ptr into memory registers instead, and since @ptr never escaped
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| 97 | * from that, it proved that the inline asm wasn't touching any of
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| 98 | * it. This version works well with both compilers, i.e. we're telling
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| 99 | * the compiler that the inline asm absolutely may see the contents
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| 100 | * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
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| 101 |
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| 102 | # define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
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| 103 | #endif
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| 104 |
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| 105 |
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| 106 | #ifndef barrier_before_unreachable
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| 107 | # define barrier_before_unreachable() do { } while (0)
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| 108 | #endif
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| 109 |
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| 110 |
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| 111 | #ifdef CONFIG_OBJTOOL
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| 112 | |
| 113 | * These macros help objtool understand GCC code flow for unreachable code.
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| 114 | * The __COUNTER__ based labels are a hack to make each instance of the macros
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| 115 | * unique, to convince GCC not to merge duplicate inline asm statements.
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| 116 |
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| 117 | #define __stringify_label(n) #n
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| 118 |
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| 119 | #define __annotate_unreachable(c) ({ \
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| 120 | asm volatile(__stringify_label(c) ":\n\t" \
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| 121 | ".pushsection .discard.unreachable\n\t" \
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| 122 | ".long " __stringify_label(c) "b - .\n\t" \
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| 123 | ".popsection\n\t" : : "i" (c)); \
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| 124 | })
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| 125 | #define annotate_unreachable() __annotate_unreachable(__COUNTER__)
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| 126 |
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| 127 |
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| 128 | #define __annotate_jump_table __section(".rodata..c_jump_table")
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| 129 |
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| 130 | #else
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| 131 | #define annotate_unreachable()
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| 132 | #define __annotate_jump_table
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| 133 | #endif
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| 134 |
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| 135 | #ifndef unreachable
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| 136 | # define unreachable() do { \
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| 137 | annotate_unreachable(); \
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| 138 | __builtin_unreachable(); \
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| 139 | } while (0)
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| 140 | #endif
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| 141 |
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| 142 | |
| 143 | * KENTRY - kernel entry point
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| 144 | * This can be used to annotate symbols (functions or data) that are used
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| 145 | * without their linker symbol being referenced explicitly. For example,
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| 146 | * interrupt vector handlers, or functions in the kernel image that are found
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| 147 | * programatically.
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| 148 | *
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| 149 | * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
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| 150 | * are handled in their own way (with KEEP() in linker scripts).
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| 151 | *
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| 152 | * KENTRY can be avoided if the symbols in question are marked as KEEP() in the
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| 153 | * linker script. For example an architecture could KEEP() its entire
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| 154 | * boot/exception vector code rather than annotate each function and data.
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| 155 |
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| 156 | #ifndef KENTRY
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| 157 | # define KENTRY(sym) \
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| 158 | extern typeof(sym) sym; \
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| 159 | static const unsigned long __kentry_##sym \
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| 160 | __used \
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| 161 | __attribute__((__section__("___kentry+" #sym))) \
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| 162 | = (unsigned long)&sym;
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| 163 | #endif
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| 164 |
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| 165 | #ifndef RELOC_HIDE
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| 166 | # define RELOC_HIDE(ptr, off) \
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| 167 | ({ unsigned long __ptr; \
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| 168 | __ptr = (unsigned long) (ptr); \
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| 169 | (typeof(ptr)) (__ptr + (off)); })
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| 170 | #endif
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| 171 |
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| 172 | #define absolute_pointer(val) RELOC_HIDE((void *)(val), 0)
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| 173 |
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| 174 | #ifndef OPTIMIZER_HIDE_VAR
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| 175 |
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| 176 | #define OPTIMIZER_HIDE_VAR(var) \
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| 177 | __asm__ ("" : "=r" (var) : "0" (var))
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| 178 | #endif
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| 179 |
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| 180 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
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| 181 |
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| 182 | |
| 183 | * data_race - mark an expression as containing intentional data races
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| 184 | *
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| 185 | * This data_race() macro is useful for situations in which data races
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| 186 | * should be forgiven. One example is diagnostic code that accesses
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| 187 | * shared variables but is not a part of the core synchronization design.
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| 188 | *
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| 189 | * This macro *does not* affect normal code generation, but is a hint
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| 190 | * to tooling that data races here are to be ignored.
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| 191 |
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| 192 | #define data_race(expr) \
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| 193 | ({ \
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| 194 | __unqual_scalar_typeof(({ expr; })) __v = ({ \
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| 195 | __kcsan_disable_current(); \
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| 196 | expr; \
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| 197 | }); \
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| 198 | __kcsan_enable_current(); \
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| 199 | __v; \
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| 200 | })
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| 201 |
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| 202 | #endif
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| 203 |
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| 204 | |
| 205 | * Force the compiler to emit 'sym' as a symbol, so that we can reference
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| 206 | * it from inline assembler. Necessary in case 'sym' could be inlined
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| 207 | * otherwise, or eliminated entirely due to lack of references that are
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| 208 | * visible to the compiler.
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| 209 |
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| 210 | #define ___ADDRESSABLE(sym, __attrs) \
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| 211 | static void * __used __attrs \
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| 212 | __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym;
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| 213 | #define __ADDRESSABLE(sym) \
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| 214 | ___ADDRESSABLE(sym, __section(".discard.addressable"))
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| 215 |
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| 216 | |
| 217 | * offset_to_ptr - convert a relative memory offset to an absolute pointer
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| 218 | * @off: the address of the 32-bit offset value
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| 219 |
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| 220 | static inline void *offset_to_ptr(const int *off)
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| 221 | {
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| 222 | return (void *)((unsigned long)off + *off);
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| 223 | }
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| 224 |
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| 225 | #endif
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| 226 |
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| 227 |
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| 228 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
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| 229 |
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| 230 | |
| 231 | * This returns a constant expression while determining if an argument is
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| 232 | * a constant expression, most importantly without evaluating the argument.
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| 233 | * Glory to Martin Uecker <[email protected]>
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| 234 |
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| 235 | #define __is_constexpr(x) \
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| 236 | (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
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| 237 |
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| 238 | |
| 239 | * Whether 'type' is a signed type or an unsigned type. Supports scalar types,
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| 240 | * bool and also pointer types.
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| 241 |
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| 242 | #define is_signed_type(type) (((type)(-1)) < (__force type)1)
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| 243 | #define is_unsigned_type(type) (!is_signed_type(type))
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| 244 |
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| 245 | |
| 246 | * This is needed in functions which generate the stack canary, see
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| 247 | * arch/x86/kernel/smpboot.c::start_secondary() for an example.
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| 248 |
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| 249 | #define prevent_tail_call_optimization() mb()
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| 250 |
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| 251 | #include <asm/rwonce.h>
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| 252 |
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| 253 | #endif
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