arch/arm64/kernel/cpufeature.c

   1 /*
   2  * Contains CPU feature definitions
   3  *
   4  * Copyright (C) 2015 ARM Ltd.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #define pr_fmt(fmt) "alternatives: " fmt
  20
  21 #include <linux/types.h>
  22 #include <asm/cpu.h>
  23 #include <asm/cpufeature.h>
  24
  25 static bool
  26 has_id_aa64pfr0_feature(const struct arm64_cpu_capabilities *entry)
  27 {
  28         u64 val;
  29
  30         val = read_cpuid(id_aa64pfr0_el1);
  31         return (val & entry->register_mask) == entry->register_value;
  32 }
  33
  34 static const struct arm64_cpu_capabilities arm64_features[] = {
  35         {
  36                 .desc = "GIC system register CPU interface",
  37                 .capability = ARM64_HAS_SYSREG_GIC_CPUIF,
  38                 .matches = has_id_aa64pfr0_feature,
  39                 .register_mask = (0xf << 24),
  40                 .register_value = (1 << 24),
  41         },
  42         {},
  43 };
  44
  45 void check_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
  46                             const char *info)
  47 {
  48         int i;
  49
  50         for (i = 0; caps[i].desc; i++) {
  51                 if (!caps[i].matches(&caps[i]))
  52                         continue;
  53
  54                 if (!cpus_have_cap(caps[i].capability))
  55                         pr_info("%s %s\n", info, caps[i].desc);
  56                 cpus_set_cap(caps[i].capability);
  57         }
  58
  59         /* second pass allows enable() to consider interacting capabilities */
  60         for (i = 0; caps[i].desc; i++) {
  61                 if (cpus_have_cap(caps[i].capability) && caps[i].enable)
  62                         caps[i].enable();
  63         }
  64 }
  65
  66 void check_local_cpu_features(void)
  67 {
  68         check_cpu_capabilities(arm64_features, "detected feature");
  69 }