arch/arm64/kernel/cpuinfo.c

   1 /*
   2  * Record and handle CPU attributes.
   3  *
   4  * Copyright (C) 2014 ARM Ltd.
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17 #include <asm/arch_timer.h>
  18 #include <asm/cachetype.h>
  19 #include <asm/cpu.h>
  20 #include <asm/cputype.h>
  21
  22 #include <linux/bitops.h>
  23 #include <linux/init.h>
  24 #include <linux/kernel.h>
  25 #include <linux/printk.h>
  26 #include <linux/smp.h>
  27
  28 /*
  29  * In case the boot CPU is hotpluggable, we record its initial state and
  30  * current state separately. Certain system registers may contain different
  31  * values depending on configuration at or after reset.
  32  */
  33 DEFINE_PER_CPU(struct cpuinfo_arm64, cpu_data);
  34 static struct cpuinfo_arm64 boot_cpu_data;
  35
  36 static char *icache_policy_str[] = {
  37         [ICACHE_POLICY_RESERVED] = "RESERVED/UNKNOWN",
  38         [ICACHE_POLICY_AIVIVT] = "AIVIVT",
  39         [ICACHE_POLICY_VIPT] = "VIPT",
  40         [ICACHE_POLICY_PIPT] = "PIPT",
  41 };
  42
  43 unsigned long __icache_flags;
  44
  45 static void cpuinfo_detect_icache_policy(struct cpuinfo_arm64 *info)
  46 {
  47         unsigned int cpu = smp_processor_id();
  48         u32 l1ip = CTR_L1IP(info->reg_ctr);
  49
  50         if (l1ip != ICACHE_POLICY_PIPT)
  51                 set_bit(ICACHEF_ALIASING, &__icache_flags);
  52         if (l1ip == ICACHE_POLICY_AIVIVT)
  53                 set_bit(ICACHEF_AIVIVT, &__icache_flags);
  54
  55         pr_info("Detected %s I-cache on CPU%d\n", icache_policy_str[l1ip], cpu);
  56 }
  57
  58 static int check_reg_mask(char *name, u64 mask, u64 boot, u64 cur, int cpu)
  59 {
  60         if ((boot & mask) == (cur & mask))
  61                 return 0;
  62
  63         pr_warn("SANITY CHECK: Unexpected variation in %s. Boot CPU: %#016lx, CPU%d: %#016lx\n",
  64                 name, (unsigned long)boot, cpu, (unsigned long)cur);
  65
  66         return 1;
  67 }
  68
  69 #define CHECK_MASK(field, mask, boot, cur, cpu) \
  70         check_reg_mask(#field, mask, (boot)->reg_ ## field, (cur)->reg_ ## field, cpu)
  71
  72 #define CHECK(field, boot, cur, cpu) \
  73         CHECK_MASK(field, ~0ULL, boot, cur, cpu)
  74
  75 /*
  76  * Verify that CPUs don't have unexpected differences that will cause problems.
  77  */
  78 static void cpuinfo_sanity_check(struct cpuinfo_arm64 *cur)
  79 {
  80         unsigned int cpu = smp_processor_id();
  81         struct cpuinfo_arm64 *boot = &boot_cpu_data;
  82         unsigned int diff = 0;
  83
  84         /*
  85          * The kernel can handle differing I-cache policies, but otherwise
  86          * caches should look identical. Userspace JITs will make use of
  87          * *minLine.
  88          */
  89         diff |= CHECK_MASK(ctr, 0xffff3fff, boot, cur, cpu);
  90
  91         /*
  92          * Userspace may perform DC ZVA instructions. Mismatched block sizes
  93          * could result in too much or too little memory being zeroed if a
  94          * process is preempted and migrated between CPUs.
  95          */
  96         diff |= CHECK(dczid, boot, cur, cpu);
  97
  98         /* If different, timekeeping will be broken (especially with KVM) */
  99         diff |= CHECK(cntfrq, boot, cur, cpu);
 100
 101         /*
 102          * Even in big.LITTLE, processors should be identical instruction-set
 103          * wise.
 104          */
 105         diff |= CHECK(id_aa64isar0, boot, cur, cpu);
 106         diff |= CHECK(id_aa64isar1, boot, cur, cpu);
 107
 108         /*
 109          * Differing PARange support is fine as long as all peripherals and
 110          * memory are mapped within the minimum PARange of all CPUs.
 111          * Linux should not care about secure memory.
 112          * ID_AA64MMFR1 is currently RES0.
 113          */
 114         diff |= CHECK_MASK(id_aa64mmfr0, 0xffffffffffff0ff0, boot, cur, cpu);
 115         diff |= CHECK(id_aa64mmfr1, boot, cur, cpu);
 116
 117         /*
 118          * EL3 is not our concern.
 119          * ID_AA64PFR1 is currently RES0.
 120          */
 121         diff |= CHECK_MASK(id_aa64pfr0, 0xffffffffffff0fff, boot, cur, cpu);
 122         diff |= CHECK(id_aa64pfr1, boot, cur, cpu);
 123
 124         /*
 125          * If we have AArch32, we care about 32-bit features for compat. These
 126          * registers should be RES0 otherwise.
 127          */
 128         diff |= CHECK(id_isar0, boot, cur, cpu);
 129         diff |= CHECK(id_isar1, boot, cur, cpu);
 130         diff |= CHECK(id_isar2, boot, cur, cpu);
 131         diff |= CHECK(id_isar3, boot, cur, cpu);
 132         diff |= CHECK(id_isar4, boot, cur, cpu);
 133         diff |= CHECK(id_isar5, boot, cur, cpu);
 134         diff |= CHECK(id_mmfr0, boot, cur, cpu);
 135         diff |= CHECK(id_mmfr1, boot, cur, cpu);
 136         diff |= CHECK(id_mmfr2, boot, cur, cpu);
 137         diff |= CHECK(id_mmfr3, boot, cur, cpu);
 138         diff |= CHECK(id_pfr0, boot, cur, cpu);
 139         diff |= CHECK(id_pfr1, boot, cur, cpu);
 140
 141         /*
 142          * Mismatched CPU features are a recipe for disaster. Don't even
 143          * pretend to support them.
 144          */
 145         WARN_TAINT_ONCE(diff, TAINT_CPU_OUT_OF_SPEC,
 146                         "Unsupported CPU feature variation.");
 147 }
 148
 149 static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
 150 {
 151         info->reg_cntfrq = arch_timer_get_cntfrq();
 152         info->reg_ctr = read_cpuid_cachetype();
 153         info->reg_dczid = read_cpuid(DCZID_EL0);
 154         info->reg_midr = read_cpuid_id();
 155
 156         info->reg_id_aa64isar0 = read_cpuid(ID_AA64ISAR0_EL1);
 157         info->reg_id_aa64isar1 = read_cpuid(ID_AA64ISAR1_EL1);
 158         info->reg_id_aa64mmfr0 = read_cpuid(ID_AA64MMFR0_EL1);
 159         info->reg_id_aa64mmfr1 = read_cpuid(ID_AA64MMFR1_EL1);
 160         info->reg_id_aa64pfr0 = read_cpuid(ID_AA64PFR0_EL1);
 161         info->reg_id_aa64pfr1 = read_cpuid(ID_AA64PFR1_EL1);
 162
 163         info->reg_id_isar0 = read_cpuid(ID_ISAR0_EL1);
 164         info->reg_id_isar1 = read_cpuid(ID_ISAR1_EL1);
 165         info->reg_id_isar2 = read_cpuid(ID_ISAR2_EL1);
 166         info->reg_id_isar3 = read_cpuid(ID_ISAR3_EL1);
 167         info->reg_id_isar4 = read_cpuid(ID_ISAR4_EL1);
 168         info->reg_id_isar5 = read_cpuid(ID_ISAR5_EL1);
 169         info->reg_id_mmfr0 = read_cpuid(ID_MMFR0_EL1);
 170         info->reg_id_mmfr1 = read_cpuid(ID_MMFR1_EL1);
 171         info->reg_id_mmfr2 = read_cpuid(ID_MMFR2_EL1);
 172         info->reg_id_mmfr3 = read_cpuid(ID_MMFR3_EL1);
 173         info->reg_id_pfr0 = read_cpuid(ID_PFR0_EL1);
 174         info->reg_id_pfr1 = read_cpuid(ID_PFR1_EL1);
 175
 176         cpuinfo_detect_icache_policy(info);
 177 }
 178
 179 void cpuinfo_store_cpu(void)
 180 {
 181         struct cpuinfo_arm64 *info = this_cpu_ptr(&cpu_data);
 182         __cpuinfo_store_cpu(info);
 183         cpuinfo_sanity_check(info);
 184 }
 185
 186 void __init cpuinfo_store_boot_cpu(void)
 187 {
 188         struct cpuinfo_arm64 *info = &per_cpu(cpu_data, 0);
 189         __cpuinfo_store_cpu(info);
 190
 191         boot_cpu_data = *info;
 192 }