Current File : //usr/src/linux-headers-5.15.0-125-generic/include/linux/compiler.h
/* 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_STACK_VALIDATION
/*
* 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__)
#define ASM_REACHABLE \
"998:\n\t" \
".pushsection .discard.reachable\n\t" \
".long 998b - .\n\t" \
".popsection\n\t"
/* Annotate a C jump table to allow objtool to follow the code flow */
#define __annotate_jump_table __section(".rodata..c_jump_table")
#else
#define annotate_unreachable()
# define ASM_REACHABLE
#define __annotate_jump_table
#endif
#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; \
})
/*
* With CONFIG_CFI_CLANG, the compiler replaces function addresses in
* instrumented C code with jump table addresses. Architectures that
* support CFI can define this macro to return the actual function address
* when needed.
*/
#ifndef function_nocfi
#define function_nocfi(x) (x)
#endif
#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) \
static void * __section(".discard.addressable") __used \
__UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym;
/**
* 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)
/*
* 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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