arch/arm/include/asm/cpufeature.h

   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         return num < 32 ? elf_hwcap & BIT(num) : elf_hwcap2 & BIT(num - 32);
  33 }
  34
  35 #endif