1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/arm-smccc.h>
3 #include <linux/kernel.h>
4 #include <linux/psci.h>
5 #include <linux/smp.h>
6
7 #include <asm/cp15.h>
8 #include <asm/cputype.h>
9 #include <asm/proc-fns.h>
10 #include <asm/system_misc.h>
11
12 #ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
13 DEFINE_PER_CPU(harden_branch_predictor_fn_t, harden_branch_predictor_fn);
14
15 extern void cpu_v7_iciallu_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
16 extern void cpu_v7_bpiall_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
17 extern void cpu_v7_smc_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
18 extern void cpu_v7_hvc_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
19
harden_branch_predictor_bpiall(void)20 static void harden_branch_predictor_bpiall(void)
21 {
22 write_sysreg(0, BPIALL);
23 }
24
harden_branch_predictor_iciallu(void)25 static void harden_branch_predictor_iciallu(void)
26 {
27 write_sysreg(0, ICIALLU);
28 }
29
call_smc_arch_workaround_1(void)30 static void __maybe_unused call_smc_arch_workaround_1(void)
31 {
32 arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_1, NULL);
33 }
34
call_hvc_arch_workaround_1(void)35 static void __maybe_unused call_hvc_arch_workaround_1(void)
36 {
37 arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_WORKAROUND_1, NULL);
38 }
39
cpu_v7_spectre_init(void)40 static void cpu_v7_spectre_init(void)
41 {
42 const char *spectre_v2_method = NULL;
43 int cpu = smp_processor_id();
44
45 if (per_cpu(harden_branch_predictor_fn, cpu))
46 return;
47
48 switch (read_cpuid_part()) {
49 case ARM_CPU_PART_CORTEX_A8:
50 case ARM_CPU_PART_CORTEX_A9:
51 case ARM_CPU_PART_CORTEX_A12:
52 case ARM_CPU_PART_CORTEX_A17:
53 case ARM_CPU_PART_CORTEX_A73:
54 case ARM_CPU_PART_CORTEX_A75:
55 per_cpu(harden_branch_predictor_fn, cpu) =
56 harden_branch_predictor_bpiall;
57 spectre_v2_method = "BPIALL";
58 break;
59
60 case ARM_CPU_PART_CORTEX_A15:
61 case ARM_CPU_PART_BRAHMA_B15:
62 per_cpu(harden_branch_predictor_fn, cpu) =
63 harden_branch_predictor_iciallu;
64 spectre_v2_method = "ICIALLU";
65 break;
66
67 #ifdef CONFIG_ARM_PSCI
68 case ARM_CPU_PART_BRAHMA_B53:
69 /* Requires no workaround */
70 break;
71 default:
72 /* Other ARM CPUs require no workaround */
73 if (read_cpuid_implementor() == ARM_CPU_IMP_ARM)
74 break;
75 /* fallthrough */
76 /* Cortex A57/A72 require firmware workaround */
77 case ARM_CPU_PART_CORTEX_A57:
78 case ARM_CPU_PART_CORTEX_A72: {
79 struct arm_smccc_res res;
80
81 if (psci_ops.smccc_version == SMCCC_VERSION_1_0)
82 break;
83
84 switch (psci_ops.conduit) {
85 case PSCI_CONDUIT_HVC:
86 arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
87 ARM_SMCCC_ARCH_WORKAROUND_1, &res);
88 if ((int)res.a0 != 0)
89 break;
90 per_cpu(harden_branch_predictor_fn, cpu) =
91 call_hvc_arch_workaround_1;
92 cpu_do_switch_mm = cpu_v7_hvc_switch_mm;
93 spectre_v2_method = "hypervisor";
94 break;
95
96 case PSCI_CONDUIT_SMC:
97 arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
98 ARM_SMCCC_ARCH_WORKAROUND_1, &res);
99 if ((int)res.a0 != 0)
100 break;
101 per_cpu(harden_branch_predictor_fn, cpu) =
102 call_smc_arch_workaround_1;
103 cpu_do_switch_mm = cpu_v7_smc_switch_mm;
104 spectre_v2_method = "firmware";
105 break;
106
107 default:
108 break;
109 }
110 }
111 #endif
112 }
113
114 if (spectre_v2_method)
115 pr_info("CPU%u: Spectre v2: using %s workaround\n",
116 smp_processor_id(), spectre_v2_method);
117 }
118 #else
cpu_v7_spectre_init(void)119 static void cpu_v7_spectre_init(void)
120 {
121 }
122 #endif
123
cpu_v7_check_auxcr_set(bool * warned,u32 mask,const char * msg)124 static __maybe_unused bool cpu_v7_check_auxcr_set(bool *warned,
125 u32 mask, const char *msg)
126 {
127 u32 aux_cr;
128
129 asm("mrc p15, 0, %0, c1, c0, 1" : "=r" (aux_cr));
130
131 if ((aux_cr & mask) != mask) {
132 if (!*warned)
133 pr_err("CPU%u: %s", smp_processor_id(), msg);
134 *warned = true;
135 return false;
136 }
137 return true;
138 }
139
140 static DEFINE_PER_CPU(bool, spectre_warned);
141
check_spectre_auxcr(bool * warned,u32 bit)142 static bool check_spectre_auxcr(bool *warned, u32 bit)
143 {
144 return IS_ENABLED(CONFIG_HARDEN_BRANCH_PREDICTOR) &&
145 cpu_v7_check_auxcr_set(warned, bit,
146 "Spectre v2: firmware did not set auxiliary control register IBE bit, system vulnerable\n");
147 }
148
cpu_v7_ca8_ibe(void)149 void cpu_v7_ca8_ibe(void)
150 {
151 if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(6)))
152 cpu_v7_spectre_init();
153 }
154
cpu_v7_ca15_ibe(void)155 void cpu_v7_ca15_ibe(void)
156 {
157 if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(0)))
158 cpu_v7_spectre_init();
159 }
160
cpu_v7_bugs_init(void)161 void cpu_v7_bugs_init(void)
162 {
163 cpu_v7_spectre_init();
164 }
165