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201 lines
5.6 KiB
201 lines
5.6 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef _TOOLS_LINUX_COMPILER_H_ |
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#define _TOOLS_LINUX_COMPILER_H_ |
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#include <linux/compiler_types.h> |
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#ifndef __compiletime_error |
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# define __compiletime_error(message) |
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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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extern void prefix ## suffix(void) __compiletime_error(msg); \ |
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if (!(condition)) \ |
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prefix ## suffix(); \ |
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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_, __COUNTER__) |
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/* Optimization barrier */ |
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/* The "volatile" is due to gcc bugs */ |
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#define barrier() __asm__ __volatile__("": : :"memory") |
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#ifndef __always_inline |
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# define __always_inline inline __attribute__((always_inline)) |
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#endif |
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#ifndef noinline |
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#define noinline |
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#endif |
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/* Are two types/vars the same type (ignoring qualifiers)? */ |
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#ifndef __same_type |
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# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) |
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#endif |
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#ifdef __ANDROID__ |
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/* |
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* FIXME: Big hammer to get rid of tons of: |
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* "warning: always_inline function might not be inlinable" |
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* |
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* At least on android-ndk-r12/platforms/android-24/arch-arm |
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*/ |
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#undef __always_inline |
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#define __always_inline inline |
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#endif |
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#define __user |
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#define __rcu |
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#define __read_mostly |
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#ifndef __attribute_const__ |
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# define __attribute_const__ |
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#endif |
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#ifndef __maybe_unused |
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# define __maybe_unused __attribute__((unused)) |
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#endif |
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#ifndef __used |
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# define __used __attribute__((__unused__)) |
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#endif |
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#ifndef __packed |
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# define __packed __attribute__((__packed__)) |
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#endif |
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#ifndef __force |
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# define __force |
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#endif |
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#ifndef __weak |
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# define __weak __attribute__((weak)) |
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#endif |
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#ifndef likely |
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# define likely(x) __builtin_expect(!!(x), 1) |
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#endif |
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#ifndef unlikely |
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# define unlikely(x) __builtin_expect(!!(x), 0) |
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#endif |
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#ifndef __init |
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# define __init |
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#endif |
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#ifndef noinline |
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# define noinline |
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#endif |
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#include <linux/types.h> |
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/* |
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* Following functions are taken from kernel sources and |
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* break aliasing rules in their original form. |
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* |
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* While kernel is compiled with -fno-strict-aliasing, |
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* perf uses -Wstrict-aliasing=3 which makes build fail |
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* under gcc 4.4. |
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* |
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* Using extra __may_alias__ type to allow aliasing |
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* in this case. |
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*/ |
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typedef __u8 __attribute__((__may_alias__)) __u8_alias_t; |
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typedef __u16 __attribute__((__may_alias__)) __u16_alias_t; |
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typedef __u32 __attribute__((__may_alias__)) __u32_alias_t; |
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typedef __u64 __attribute__((__may_alias__)) __u64_alias_t; |
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static __always_inline void __read_once_size(const volatile void *p, void *res, int size) |
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{ |
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switch (size) { |
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case 1: *(__u8_alias_t *) res = *(volatile __u8_alias_t *) p; break; |
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case 2: *(__u16_alias_t *) res = *(volatile __u16_alias_t *) p; break; |
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case 4: *(__u32_alias_t *) res = *(volatile __u32_alias_t *) p; break; |
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case 8: *(__u64_alias_t *) res = *(volatile __u64_alias_t *) 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 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_alias_t *) p = *(__u8_alias_t *) res; break; |
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case 2: *(volatile __u16_alias_t *) p = *(__u16_alias_t *) res; break; |
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case 4: *(volatile __u32_alias_t *) p = *(__u32_alias_t *) res; break; |
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case 8: *(volatile __u64_alias_t *) p = *(__u64_alias_t *) 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 and WRITE_ONCE, but only when the compiler is aware of some |
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* particular ordering. One way to make the compiler aware of ordering is to |
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* put the two invocations of READ_ONCE or WRITE_ONCE in different C |
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* statements. |
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* |
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* These two macros will also work on aggregate data types like structs or |
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* unions. If the size of the accessed data type exceeds the word size of |
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* the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will |
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* fall back to memcpy and print a compile-time warning. |
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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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#define READ_ONCE(x) \ |
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({ \ |
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union { typeof(x) __val; char __c[1]; } __u = \ |
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{ .__c = { 0 } }; \ |
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__read_once_size(&(x), __u.__c, sizeof(x)); \ |
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__u.__val; \ |
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}) |
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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 = (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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#ifndef __fallthrough |
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# define __fallthrough |
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#endif |
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/* Indirect macros required for expanded argument pasting, eg. __LINE__. */ |
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#define ___PASTE(a, b) a##b |
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#define __PASTE(a, b) ___PASTE(a, b) |
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#endif /* _TOOLS_LINUX_COMPILER_H */
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