arch/arm/mm/proc-v7-bugs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/arm-smccc.h>
   3 #include <linux/kernel.h>
   4 #include <linux/smp.h>
   5
   6 #include <asm/cp15.h>
   7 #include <asm/cputype.h>
   8 #include <asm/proc-fns.h>
   9 #include <asm/system_misc.h>
  10
  11 #ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
  12 DEFINE_PER_CPU(harden_branch_predictor_fn_t, harden_branch_predictor_fn);
  13
  14 extern void cpu_v7_iciallu_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
  15 extern void cpu_v7_bpiall_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
  16 extern void cpu_v7_smc_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
  17 extern void cpu_v7_hvc_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
  18
  19 static void harden_branch_predictor_bpiall(void)
  20 {
  21         write_sysreg(0, BPIALL);
  22 }
  23
  24 static void harden_branch_predictor_iciallu(void)
  25 {
  26         write_sysreg(0, ICIALLU);
  27 }
  28
  29 static void __maybe_unused call_smc_arch_workaround_1(void)
  30 {
  31         arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_1, NULL);
  32 }
  33
  34 static void __maybe_unused call_hvc_arch_workaround_1(void)
  35 {
  36         arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_WORKAROUND_1, NULL);
  37 }
  38
  39 static void cpu_v7_spectre_init(void)
  40 {
  41         const char *spectre_v2_method = NULL;
  42         int cpu = smp_processor_id();
  43
  44         if (per_cpu(harden_branch_predictor_fn, cpu))
  45                 return;
  46
  47         switch (read_cpuid_part()) {
  48         case ARM_CPU_PART_CORTEX_A8:
  49         case ARM_CPU_PART_CORTEX_A9:
  50         case ARM_CPU_PART_CORTEX_A12:
  51         case ARM_CPU_PART_CORTEX_A17:
  52         case ARM_CPU_PART_CORTEX_A73:
  53         case ARM_CPU_PART_CORTEX_A75:
  54                 per_cpu(harden_branch_predictor_fn, cpu) =
  55                         harden_branch_predictor_bpiall;
  56                 spectre_v2_method = "BPIALL";
  57                 break;
  58
  59         case ARM_CPU_PART_CORTEX_A15:
  60         case ARM_CPU_PART_BRAHMA_B15:
  61                 per_cpu(harden_branch_predictor_fn, cpu) =
  62                         harden_branch_predictor_iciallu;
  63                 spectre_v2_method = "ICIALLU";
  64                 break;
  65
  66 #ifdef CONFIG_ARM_PSCI
  67         case ARM_CPU_PART_BRAHMA_B53:
  68                 /* Requires no workaround */
  69                 break;
  70         default:
  71                 /* Other ARM CPUs require no workaround */
  72                 if (read_cpuid_implementor() == ARM_CPU_IMP_ARM)
  73                         break;
  74                 /* fallthrough */
  75                 /* Cortex A57/A72 require firmware workaround */
  76         case ARM_CPU_PART_CORTEX_A57:
  77         case ARM_CPU_PART_CORTEX_A72: {
  78                 struct arm_smccc_res res;
  79
  80                 arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
  81                                      ARM_SMCCC_ARCH_WORKAROUND_1, &res);
  82                 if ((int)res.a0 != 0)
  83                         return;
  84
  85                 switch (arm_smccc_1_1_get_conduit()) {
  86                 case SMCCC_CONDUIT_HVC:
  87                         per_cpu(harden_branch_predictor_fn, cpu) =
  88                                 call_hvc_arch_workaround_1;
  89                         cpu_do_switch_mm = cpu_v7_hvc_switch_mm;
  90                         spectre_v2_method = "hypervisor";
  91                         break;
  92
  93                 case SMCCC_CONDUIT_SMC:
  94                         per_cpu(harden_branch_predictor_fn, cpu) =
  95                                 call_smc_arch_workaround_1;
  96                         cpu_do_switch_mm = cpu_v7_smc_switch_mm;
  97                         spectre_v2_method = "firmware";
  98                         break;
  99
 100                 default:
 101                         break;
 102                 }
 103         }
 104 #endif
 105         }
 106
 107         if (spectre_v2_method)
 108                 pr_info("CPU%u: Spectre v2: using %s workaround\n",
 109                         smp_processor_id(), spectre_v2_method);
 110 }
 111 #else
 112 static void cpu_v7_spectre_init(void)
 113 {
 114 }
 115 #endif
 116
 117 static __maybe_unused bool cpu_v7_check_auxcr_set(bool *warned,
 118                                                   u32 mask, const char *msg)
 119 {
 120         u32 aux_cr;
 121
 122         asm("mrc p15, 0, %0, c1, c0, 1" : "=r" (aux_cr));
 123
 124         if ((aux_cr & mask) != mask) {
 125                 if (!*warned)
 126                         pr_err("CPU%u: %s", smp_processor_id(), msg);
 127                 *warned = true;
 128                 return false;
 129         }
 130         return true;
 131 }
 132
 133 static DEFINE_PER_CPU(bool, spectre_warned);
 134
 135 static bool check_spectre_auxcr(bool *warned, u32 bit)
 136 {
 137         return IS_ENABLED(CONFIG_HARDEN_BRANCH_PREDICTOR) &&
 138                 cpu_v7_check_auxcr_set(warned, bit,
 139                                        "Spectre v2: firmware did not set auxiliary control register IBE bit, system vulnerable\n");
 140 }
 141
 142 void cpu_v7_ca8_ibe(void)
 143 {
 144         if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(6)))
 145                 cpu_v7_spectre_init();
 146 }
 147
 148 void cpu_v7_ca15_ibe(void)
 149 {
 150         if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(0)))
 151                 cpu_v7_spectre_init();
 152 }
 153
 154 void cpu_v7_bugs_init(void)
 155 {
 156         cpu_v7_spectre_init();
 157 }