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       1                 :            : /* SPDX-License-Identifier: GPL-2.0-only */
       2                 :            : /*
       3                 :            :  * Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org>
       4                 :            :  */
       5                 :            : 
       6                 :            : #ifndef __ASM_CPUFEATURE_H
       7                 :            : #define __ASM_CPUFEATURE_H
       8                 :            : 
       9                 :            : #include <linux/log2.h>
      10                 :            : #include <asm/hwcap.h>
      11                 :            : 
      12                 :            : /*
      13                 :            :  * Due to the fact that ELF_HWCAP is a 32-bit type on ARM, and given the number
      14                 :            :  * of optional CPU features it defines, ARM's CPU hardware capability bits have
      15                 :            :  * been distributed over separate elf_hwcap and elf_hwcap2 variables, each of
      16                 :            :  * which covers a subset of the available CPU features.
      17                 :            :  *
      18                 :            :  * Currently, only a few of those are suitable for automatic module loading
      19                 :            :  * (which is the primary use case of this facility) and those happen to be all
      20                 :            :  * covered by HWCAP2. So let's only cover those via the cpu_feature()
      21                 :            :  * convenience macro for now (which is used by module_cpu_feature_match()).
      22                 :            :  * However, all capabilities are exposed via the modalias, and can be matched
      23                 :            :  * using an explicit MODULE_DEVICE_TABLE() that uses __hwcap_feature() directly.
      24                 :            :  */
      25                 :            : #define MAX_CPU_FEATURES        64
      26                 :            : #define __hwcap_feature(x)      ilog2(HWCAP_ ## x)
      27                 :            : #define __hwcap2_feature(x)     (32 + ilog2(HWCAP2_ ## x))
      28                 :            : #define cpu_feature(x)          __hwcap2_feature(x)
      29                 :            : 
      30                 :            : static inline bool cpu_have_feature(unsigned int num)
      31                 :            : {
      32                 :          3 :         return num < 32 ? elf_hwcap & BIT(num) : elf_hwcap2 & BIT(num - 32);
      33                 :            : }
      34                 :            : 
      35                 :            : #endif