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Diffstat (limited to 'include/linux/compiler.h')
| -rw-r--r-- | include/linux/compiler.h | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h new file mode 100644 index 000000000..973a1bfd7 --- /dev/null +++ b/include/linux/compiler.h @@ -0,0 +1,248 @@ +/* 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) + +/* + * 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 */ |