356 lines
11 KiB
C
356 lines
11 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_COMPILER_H
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#define __LINUX_COMPILER_H
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#include <linux/compiler_types.h>
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#ifndef __ASSEMBLY__
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#ifdef __KERNEL__
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/*
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* Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
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* to disable branch tracing on a per file basis.
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*/
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#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
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&& !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
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void ftrace_likely_update(struct ftrace_likely_data *f, int val,
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int expect, int is_constant);
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#define likely_notrace(x) __builtin_expect(!!(x), 1)
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#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
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#define __branch_check__(x, expect, is_constant) ({ \
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int ______r; \
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static struct ftrace_likely_data \
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__attribute__((__aligned__(4))) \
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__attribute__((section("_ftrace_annotated_branch"))) \
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______f = { \
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.data.func = __func__, \
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.data.file = __FILE__, \
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.data.line = __LINE__, \
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}; \
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______r = __builtin_expect(!!(x), expect); \
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ftrace_likely_update(&______f, ______r, \
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expect, is_constant); \
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______r; \
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})
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/*
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* Using __builtin_constant_p(x) to ignore cases where the return
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* value is always the same. This idea is taken from a similar patch
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* written by Daniel Walker.
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*/
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# ifndef likely
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# define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x)))
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# endif
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# ifndef unlikely
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# define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x)))
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# endif
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#ifdef CONFIG_PROFILE_ALL_BRANCHES
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/*
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* "Define 'is'", Bill Clinton
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* "Define 'if'", Steven Rostedt
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*/
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#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
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#define __trace_if(cond) \
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if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
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({ \
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int ______r; \
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static struct ftrace_branch_data \
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__attribute__((__aligned__(4))) \
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__attribute__((section("_ftrace_branch"))) \
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______f = { \
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.func = __func__, \
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.file = __FILE__, \
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.line = __LINE__, \
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}; \
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______r = !!(cond); \
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______f.miss_hit[______r]++; \
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______r; \
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}))
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#endif /* CONFIG_PROFILE_ALL_BRANCHES */
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#else
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# define likely(x) __builtin_expect(!!(x), 1)
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# define unlikely(x) __builtin_expect(!!(x), 0)
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#endif
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/* Optimization barrier */
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#ifndef barrier
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# define barrier() __memory_barrier()
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#endif
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#ifndef barrier_data
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# define barrier_data(ptr) barrier()
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#endif
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/* Unreachable code */
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#ifdef CONFIG_STACK_VALIDATION
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/*
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* These macros help objtool understand GCC code flow for unreachable code.
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* The __COUNTER__ based labels are a hack to make each instance of the macros
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* unique, to convince GCC not to merge duplicate inline asm statements.
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*/
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#define annotate_reachable() ({ \
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asm volatile("%c0:\n\t" \
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".pushsection .discard.reachable\n\t" \
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".long %c0b - .\n\t" \
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".popsection\n\t" : : "i" (__COUNTER__)); \
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})
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#define annotate_unreachable() ({ \
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asm volatile("%c0:\n\t" \
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".pushsection .discard.unreachable\n\t" \
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".long %c0b - .\n\t" \
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".popsection\n\t" : : "i" (__COUNTER__)); \
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})
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#define ASM_UNREACHABLE \
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"999:\n\t" \
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".pushsection .discard.unreachable\n\t" \
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".long 999b - .\n\t" \
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".popsection\n\t"
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#else
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#define annotate_reachable()
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#define annotate_unreachable()
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#endif
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#ifndef ASM_UNREACHABLE
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# define ASM_UNREACHABLE
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#endif
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#ifndef unreachable
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# define unreachable() do { annotate_reachable(); do { } while (1); } while (0)
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#endif
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/*
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* KENTRY - kernel entry point
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* This can be used to annotate symbols (functions or data) that are used
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* without their linker symbol being referenced explicitly. For example,
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* interrupt vector handlers, or functions in the kernel image that are found
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* programatically.
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*
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* Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
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* are handled in their own way (with KEEP() in linker scripts).
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*
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* KENTRY can be avoided if the symbols in question are marked as KEEP() in the
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* linker script. For example an architecture could KEEP() its entire
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* boot/exception vector code rather than annotate each function and data.
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*/
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#ifndef KENTRY
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# define KENTRY(sym) \
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extern typeof(sym) sym; \
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static const unsigned long __kentry_##sym \
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__used \
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__attribute__((section("___kentry" "+" #sym ), used)) \
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= (unsigned long)&sym;
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#endif
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#ifndef RELOC_HIDE
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# define RELOC_HIDE(ptr, off) \
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({ unsigned long __ptr; \
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__ptr = (unsigned long) (ptr); \
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(typeof(ptr)) (__ptr + (off)); })
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#endif
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#ifndef OPTIMIZER_HIDE_VAR
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#define OPTIMIZER_HIDE_VAR(var) barrier()
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#endif
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/* Not-quite-unique ID. */
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#ifndef __UNIQUE_ID
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# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
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#endif
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#include <uapi/linux/types.h>
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#define __READ_ONCE_SIZE \
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({ \
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switch (size) { \
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case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \
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case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \
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case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \
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case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \
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default: \
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barrier(); \
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__builtin_memcpy((void *)res, (const void *)p, size); \
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barrier(); \
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} \
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})
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static __always_inline
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void __read_once_size(const volatile void *p, void *res, int size)
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{
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__READ_ONCE_SIZE;
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}
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#ifdef CONFIG_KASAN
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/*
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* This function is not 'inline' because __no_sanitize_address confilcts
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* with inlining. Attempt to inline it may cause a build failure.
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* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
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* '__maybe_unused' allows us to avoid defined-but-not-used warnings.
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*/
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static __no_sanitize_address __maybe_unused
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void __read_once_size_nocheck(const volatile void *p, void *res, int size)
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{
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__READ_ONCE_SIZE;
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}
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#else
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static __always_inline
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void __read_once_size_nocheck(const volatile void *p, void *res, int size)
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{
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__READ_ONCE_SIZE;
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}
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#endif
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static __always_inline void __write_once_size(volatile void *p, void *res, int size)
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{
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switch (size) {
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case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
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case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
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case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
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case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
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default:
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barrier();
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__builtin_memcpy((void *)p, (const void *)res, size);
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barrier();
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}
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}
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/*
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* Prevent the compiler from merging or refetching reads or writes. The
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* compiler is also forbidden from reordering successive instances of
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* READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
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* compiler is aware of some particular ordering. One way to make the
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* compiler aware of ordering is to put the two invocations of READ_ONCE,
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* WRITE_ONCE or ACCESS_ONCE() in different C statements.
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*
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* In contrast to ACCESS_ONCE these two macros will also work on aggregate
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* data types like structs or unions. If the size of the accessed data
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* type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
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* READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at
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* least two memcpy()s: one for the __builtin_memcpy() and then one for
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* the macro doing the copy of variable - '__u' allocated on the stack.
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*
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* Their two major use cases are: (1) Mediating communication between
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* process-level code and irq/NMI handlers, all running on the same CPU,
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* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
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* mutilate accesses that either do not require ordering or that interact
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* with an explicit memory barrier or atomic instruction that provides the
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* required ordering.
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*/
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#include <asm/barrier.h>
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#define __READ_ONCE(x, check) \
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({ \
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union { typeof(x) __val; char __c[1]; } __u; \
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if (check) \
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__read_once_size(&(x), __u.__c, sizeof(x)); \
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else \
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__read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
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smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
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__u.__val; \
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})
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#define READ_ONCE(x) __READ_ONCE(x, 1)
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/*
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* Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
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* to hide memory access from KASAN.
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*/
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#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
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#define WRITE_ONCE(x, val) \
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({ \
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union { typeof(x) __val; char __c[1]; } __u = \
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{ .__val = (__force typeof(x)) (val) }; \
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__write_once_size(&(x), __u.__c, sizeof(x)); \
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__u.__val; \
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})
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#endif /* __KERNEL__ */
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#endif /* __ASSEMBLY__ */
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/* Compile time object size, -1 for unknown */
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#ifndef __compiletime_object_size
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# define __compiletime_object_size(obj) -1
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#endif
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#ifndef __compiletime_warning
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# define __compiletime_warning(message)
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#endif
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#ifndef __compiletime_error
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# define __compiletime_error(message)
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/*
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* Sparse complains of variable sized arrays due to the temporary variable in
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* __compiletime_assert. Unfortunately we can't just expand it out to make
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* sparse see a constant array size without breaking compiletime_assert on old
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* versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
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*/
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# ifndef __CHECKER__
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# define __compiletime_error_fallback(condition) \
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do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
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# endif
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#endif
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#ifndef __compiletime_error_fallback
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# define __compiletime_error_fallback(condition) do { } while (0)
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#endif
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#ifdef __OPTIMIZE__
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# define __compiletime_assert(condition, msg, prefix, suffix) \
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do { \
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bool __cond = !(condition); \
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extern void prefix ## suffix(void) __compiletime_error(msg); \
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if (__cond) \
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prefix ## suffix(); \
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__compiletime_error_fallback(__cond); \
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} while (0)
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#else
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# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
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#endif
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#define _compiletime_assert(condition, msg, prefix, suffix) \
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__compiletime_assert(condition, msg, prefix, suffix)
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/**
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* compiletime_assert - break build and emit msg if condition is false
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* @condition: a compile-time constant condition to check
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* @msg: a message to emit if condition is false
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*
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* In tradition of POSIX assert, this macro will break the build if the
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* supplied condition is *false*, emitting the supplied error message if the
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* compiler has support to do so.
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*/
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#define compiletime_assert(condition, msg) \
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_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
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#define compiletime_assert_atomic_type(t) \
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compiletime_assert(__native_word(t), \
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"Need native word sized stores/loads for atomicity.")
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/*
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* Prevent the compiler from merging or refetching accesses. The compiler
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* is also forbidden from reordering successive instances of ACCESS_ONCE(),
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* but only when the compiler is aware of some particular ordering. One way
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* to make the compiler aware of ordering is to put the two invocations of
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* ACCESS_ONCE() in different C statements.
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*
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* ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
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* on a union member will work as long as the size of the member matches the
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* size of the union and the size is smaller than word size.
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*
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* The major use cases of ACCESS_ONCE used to be (1) Mediating communication
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* between process-level code and irq/NMI handlers, all running on the same CPU,
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* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
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* mutilate accesses that either do not require ordering or that interact
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* with an explicit memory barrier or atomic instruction that provides the
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* required ordering.
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*
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* If possible use READ_ONCE()/WRITE_ONCE() instead.
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*/
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#define __ACCESS_ONCE(x) ({ \
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__maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
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(volatile typeof(x) *)&(x); })
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#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
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#endif /* __LINUX_COMPILER_H */
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