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- /* SPDX-License-Identifier: GPL-2.0 */
- #ifndef __LINUX_COMPILER_H
- #define __LINUX_COMPILER_H
- #include <linux/compiler_types.h>
- #ifndef __ASSEMBLY__
- #ifdef __KERNEL__
- /*
- * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
- * to disable branch tracing on a per file basis.
- */
- #if defined(CONFIG_TRACE_BRANCH_PROFILING) \
- && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
- void ftrace_likely_update(struct ftrace_likely_data *f, int val,
- int expect, int is_constant);
- #define likely_notrace(x) __builtin_expect(!!(x), 1)
- #define unlikely_notrace(x) __builtin_expect(!!(x), 0)
- #define __branch_check__(x, expect, is_constant) ({ \
- long ______r; \
- static struct ftrace_likely_data \
- __aligned(4) \
- __section("_ftrace_annotated_branch") \
- ______f = { \
- .data.func = __func__, \
- .data.file = __FILE__, \
- .data.line = __LINE__, \
- }; \
- ______r = __builtin_expect(!!(x), expect); \
- ftrace_likely_update(&______f, ______r, \
- expect, is_constant); \
- ______r; \
- })
- /*
- * Using __builtin_constant_p(x) to ignore cases where the return
- * value is always the same. This idea is taken from a similar patch
- * written by Daniel Walker.
- */
- # ifndef likely
- # define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x)))
- # endif
- # ifndef unlikely
- # define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x)))
- # endif
- #ifdef CONFIG_PROFILE_ALL_BRANCHES
- /*
- * "Define 'is'", Bill Clinton
- * "Define 'if'", Steven Rostedt
- */
- #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
- #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
- #define __trace_if_value(cond) ({ \
- static struct ftrace_branch_data \
- __aligned(4) \
- __section("_ftrace_branch") \
- __if_trace = { \
- .func = __func__, \
- .file = __FILE__, \
- .line = __LINE__, \
- }; \
- (cond) ? \
- (__if_trace.miss_hit[1]++,1) : \
- (__if_trace.miss_hit[0]++,0); \
- })
- #endif /* CONFIG_PROFILE_ALL_BRANCHES */
- #else
- # define likely(x) __builtin_expect(!!(x), 1)
- # define unlikely(x) __builtin_expect(!!(x), 0)
- # define likely_notrace(x) likely(x)
- # define unlikely_notrace(x) unlikely(x)
- #endif
- /* Optimization barrier */
- #ifndef barrier
- /* The "volatile" is due to gcc bugs */
- # define barrier() __asm__ __volatile__("": : :"memory")
- #endif
- #ifndef barrier_data
- /*
- * This version is i.e. to prevent dead stores elimination on @ptr
- * where gcc and llvm may behave differently when otherwise using
- * normal barrier(): while gcc behavior gets along with a normal
- * barrier(), llvm needs an explicit input variable to be assumed
- * clobbered. The issue is as follows: while the inline asm might
- * access any memory it wants, the compiler could have fit all of
- * @ptr into memory registers instead, and since @ptr never escaped
- * from that, it proved that the inline asm wasn't touching any of
- * it. This version works well with both compilers, i.e. we're telling
- * the compiler that the inline asm absolutely may see the contents
- * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
- */
- # define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
- #endif
- /* workaround for GCC PR82365 if needed */
- #ifndef barrier_before_unreachable
- # define barrier_before_unreachable() do { } while (0)
- #endif
- /* Unreachable code */
- #ifdef CONFIG_OBJTOOL
- /*
- * These macros help objtool understand GCC code flow for unreachable code.
- * The __COUNTER__ based labels are a hack to make each instance of the macros
- * unique, to convince GCC not to merge duplicate inline asm statements.
- */
- #define __stringify_label(n) #n
- #define __annotate_unreachable(c) ({ \
- asm volatile(__stringify_label(c) ":\n\t" \
- ".pushsection .discard.unreachable\n\t" \
- ".long " __stringify_label(c) "b - .\n\t" \
- ".popsection\n\t" : : "i" (c)); \
- })
- #define annotate_unreachable() __annotate_unreachable(__COUNTER__)
- /* Annotate a C jump table to allow objtool to follow the code flow */
- #define __annotate_jump_table __section(".rodata..c_jump_table")
- #else /* !CONFIG_OBJTOOL */
- #define annotate_unreachable()
- #define __annotate_jump_table
- #endif /* CONFIG_OBJTOOL */
- #ifndef unreachable
- # define unreachable() do { \
- annotate_unreachable(); \
- __builtin_unreachable(); \
- } while (0)
- #endif
- /*
- * KENTRY - kernel entry point
- * This can be used to annotate symbols (functions or data) that are used
- * without their linker symbol being referenced explicitly. For example,
- * interrupt vector handlers, or functions in the kernel image that are found
- * programatically.
- *
- * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
- * are handled in their own way (with KEEP() in linker scripts).
- *
- * KENTRY can be avoided if the symbols in question are marked as KEEP() in the
- * linker script. For example an architecture could KEEP() its entire
- * boot/exception vector code rather than annotate each function and data.
- */
- #ifndef KENTRY
- # define KENTRY(sym) \
- extern typeof(sym) sym; \
- static const unsigned long __kentry_##sym \
- __used \
- __attribute__((__section__("___kentry+" #sym))) \
- = (unsigned long)&sym;
- #endif
- #ifndef RELOC_HIDE
- # define RELOC_HIDE(ptr, off) \
- ({ unsigned long __ptr; \
- __ptr = (unsigned long) (ptr); \
- (typeof(ptr)) (__ptr + (off)); })
- #endif
- #define absolute_pointer(val) RELOC_HIDE((void *)(val), 0)
- #ifndef OPTIMIZER_HIDE_VAR
- /* Make the optimizer believe the variable can be manipulated arbitrarily. */
- #define OPTIMIZER_HIDE_VAR(var) \
- __asm__ ("" : "=r" (var) : "0" (var))
- #endif
- /* Not-quite-unique ID. */
- #ifndef __UNIQUE_ID
- # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
- #endif
- /**
- * data_race - mark an expression as containing intentional data races
- *
- * This data_race() macro is useful for situations in which data races
- * should be forgiven. One example is diagnostic code that accesses
- * shared variables but is not a part of the core synchronization design.
- *
- * This macro *does not* affect normal code generation, but is a hint
- * to tooling that data races here are to be ignored.
- */
- #define data_race(expr) \
- ({ \
- __unqual_scalar_typeof(({ expr; })) __v = ({ \
- __kcsan_disable_current(); \
- expr; \
- }); \
- __kcsan_enable_current(); \
- __v; \
- })
- #endif /* __KERNEL__ */
- /*
- * Force the compiler to emit 'sym' as a symbol, so that we can reference
- * it from inline assembler. Necessary in case 'sym' could be inlined
- * otherwise, or eliminated entirely due to lack of references that are
- * visible to the compiler.
- */
- #define ___ADDRESSABLE(sym, __attrs) \
- static void * __used __attrs \
- __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym;
- #define __ADDRESSABLE(sym) \
- ___ADDRESSABLE(sym, __section(".discard.addressable"))
- /**
- * offset_to_ptr - convert a relative memory offset to an absolute pointer
- * @off: the address of the 32-bit offset value
- */
- static inline void *offset_to_ptr(const int *off)
- {
- return (void *)((unsigned long)off + *off);
- }
- #endif /* __ASSEMBLY__ */
- /* &a[0] degrades to a pointer: a different type from an array */
- #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
- /*
- * Whether 'type' is a signed type or an unsigned type. Supports scalar types,
- * bool and also pointer types.
- */
- #define is_signed_type(type) (((type)(-1)) < (__force type)1)
- #define is_unsigned_type(type) (!is_signed_type(type))
- /*
- * This is needed in functions which generate the stack canary, see
- * arch/x86/kernel/smpboot.c::start_secondary() for an example.
- */
- #define prevent_tail_call_optimization() mb()
- #include <asm/rwonce.h>
- #endif /* __LINUX_COMPILER_H */
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