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Linux kernel mirror (for testing)
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kernel
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linux
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
13DEFINE_PER_CPU(harden_branch_predictor_fn_t, harden_branch_predictor_fn);
14
15extern void cpu_v7_iciallu_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
16extern void cpu_v7_bpiall_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
17extern void cpu_v7_smc_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
18extern void cpu_v7_hvc_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
19
20static void harden_branch_predictor_bpiall(void)
21{
22 write_sysreg(0, BPIALL);
23}
24
25static void harden_branch_predictor_iciallu(void)
26{
27 write_sysreg(0, ICIALLU);
28}
29
30static void __maybe_unused call_smc_arch_workaround_1(void)
31{
32 arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_1, NULL);
33}
34
35static void __maybe_unused call_hvc_arch_workaround_1(void)
36{
37 arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_WORKAROUND_1, NULL);
38}
39
40static 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 default:
69 /* Other ARM CPUs require no workaround */
70 if (read_cpuid_implementor() == ARM_CPU_IMP_ARM)
71 break;
72 /* fallthrough */
73 /* Cortex A57/A72 require firmware workaround */
74 case ARM_CPU_PART_CORTEX_A57:
75 case ARM_CPU_PART_CORTEX_A72: {
76 struct arm_smccc_res res;
77
78 if (psci_ops.smccc_version == SMCCC_VERSION_1_0)
79 break;
80
81 switch (psci_ops.conduit) {
82 case PSCI_CONDUIT_HVC:
83 arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
84 ARM_SMCCC_ARCH_WORKAROUND_1, &res);
85 if ((int)res.a0 != 0)
86 break;
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 PSCI_CONDUIT_SMC:
94 arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
95 ARM_SMCCC_ARCH_WORKAROUND_1, &res);
96 if ((int)res.a0 != 0)
97 break;
98 per_cpu(harden_branch_predictor_fn, cpu) =
99 call_smc_arch_workaround_1;
100 cpu_do_switch_mm = cpu_v7_smc_switch_mm;
101 spectre_v2_method = "firmware";
102 break;
103
104 default:
105 break;
106 }
107 }
108#endif
109 }
110
111 if (spectre_v2_method)
112 pr_info("CPU%u: Spectre v2: using %s workaround\n",
113 smp_processor_id(), spectre_v2_method);
114}
115#else
116static void cpu_v7_spectre_init(void)
117{
118}
119#endif
120
121static __maybe_unused bool cpu_v7_check_auxcr_set(bool *warned,
122 u32 mask, const char *msg)
123{
124 u32 aux_cr;
125
126 asm("mrc p15, 0, %0, c1, c0, 1" : "=r" (aux_cr));
127
128 if ((aux_cr & mask) != mask) {
129 if (!*warned)
130 pr_err("CPU%u: %s", smp_processor_id(), msg);
131 *warned = true;
132 return false;
133 }
134 return true;
135}
136
137static DEFINE_PER_CPU(bool, spectre_warned);
138
139static bool check_spectre_auxcr(bool *warned, u32 bit)
140{
141 return IS_ENABLED(CONFIG_HARDEN_BRANCH_PREDICTOR) &&
142 cpu_v7_check_auxcr_set(warned, bit,
143 "Spectre v2: firmware did not set auxiliary control register IBE bit, system vulnerable\n");
144}
145
146void cpu_v7_ca8_ibe(void)
147{
148 if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(6)))
149 cpu_v7_spectre_init();
150}
151
152void cpu_v7_ca15_ibe(void)
153{
154 if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(0)))
155 cpu_v7_spectre_init();
156}
157
158void cpu_v7_bugs_init(void)
159{
160 cpu_v7_spectre_init();
161}