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// SPDX-License-Identifier: GPL-2.0
#include <linux/arm-smccc.h>
#include <linux/kernel.h>
#include <linux/psci.h>
#include <linux/smp.h>
#include <asm/cp15.h>
#include <asm/cputype.h>
#include <asm/proc-fns.h>
#include <asm/spectre.h>
#include <asm/system_misc.h>
#ifdef CONFIG_ARM_PSCI
#define SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED 1
static int __maybe_unused spectre_v2_get_cpu_fw_mitigation_state(void)
{
struct arm_smccc_res res;
arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
ARM_SMCCC_ARCH_WORKAROUND_1, &res);
switch ((int)res.a0) {
case SMCCC_RET_SUCCESS:
return SPECTRE_MITIGATED;
case SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED:
return SPECTRE_UNAFFECTED;
default:
return SPECTRE_VULNERABLE;
}
}
#else
static int __maybe_unused spectre_v2_get_cpu_fw_mitigation_state(void)
{
return SPECTRE_VULNERABLE;
}
#endif
#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
DEFINE_PER_CPU(harden_branch_predictor_fn_t, harden_branch_predictor_fn);
extern void cpu_v7_iciallu_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
extern void cpu_v7_bpiall_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
extern void cpu_v7_smc_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
extern void cpu_v7_hvc_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
static void harden_branch_predictor_bpiall(void)
{
write_sysreg(0, BPIALL);
}
static void harden_branch_predictor_iciallu(void)
{
write_sysreg(0, ICIALLU);
}
static void __maybe_unused call_smc_arch_workaround_1(void)
{
arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_1, NULL);
}
static void __maybe_unused call_hvc_arch_workaround_1(void)
{
arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_WORKAROUND_1, NULL);
}
static unsigned int spectre_v2_install_workaround(unsigned int method)
{
const char *spectre_v2_method = NULL;
int cpu = smp_processor_id();
if (per_cpu(harden_branch_predictor_fn, cpu))
return SPECTRE_MITIGATED;
switch (method) {
case SPECTRE_V2_METHOD_BPIALL:
per_cpu(harden_branch_predictor_fn, cpu) =
harden_branch_predictor_bpiall;
spectre_v2_method = "BPIALL";
break;
case SPECTRE_V2_METHOD_ICIALLU:
per_cpu(harden_branch_predictor_fn, cpu) =
harden_branch_predictor_iciallu;
spectre_v2_method = "ICIALLU";
break;
case SPECTRE_V2_METHOD_HVC:
per_cpu(harden_branch_predictor_fn, cpu) =
call_hvc_arch_workaround_1;
cpu_do_switch_mm = cpu_v7_hvc_switch_mm;
spectre_v2_method = "hypervisor";
break;
case SPECTRE_V2_METHOD_SMC:
per_cpu(harden_branch_predictor_fn, cpu) =
call_smc_arch_workaround_1;
cpu_do_switch_mm = cpu_v7_smc_switch_mm;
spectre_v2_method = "firmware";
break;
}
if (spectre_v2_method)
pr_info("CPU%u: Spectre v2: using %s workaround\n",
smp_processor_id(), spectre_v2_method);
return SPECTRE_MITIGATED;
}
#else
static unsigned int spectre_v2_install_workaround(unsigned int method)
{
pr_info_once("Spectre V2: workarounds disabled by configuration\n");
return SPECTRE_VULNERABLE;
}
#endif
static void cpu_v7_spectre_v2_init(void)
{
unsigned int state, method = 0;
switch (read_cpuid_part()) {
case ARM_CPU_PART_CORTEX_A8:
case ARM_CPU_PART_CORTEX_A9:
case ARM_CPU_PART_CORTEX_A12:
case ARM_CPU_PART_CORTEX_A17:
case ARM_CPU_PART_CORTEX_A73:
case ARM_CPU_PART_CORTEX_A75:
state = SPECTRE_MITIGATED;
method = SPECTRE_V2_METHOD_BPIALL;
break;
case ARM_CPU_PART_CORTEX_A15:
case ARM_CPU_PART_BRAHMA_B15:
state = SPECTRE_MITIGATED;
method = SPECTRE_V2_METHOD_ICIALLU;
break;
case ARM_CPU_PART_BRAHMA_B53:
/* Requires no workaround */
state = SPECTRE_UNAFFECTED;
break;
default:
/* Other ARM CPUs require no workaround */
if (read_cpuid_implementor() == ARM_CPU_IMP_ARM) {
state = SPECTRE_UNAFFECTED;
break;
}
/* fallthrough */
/* Cortex A57/A72 require firmware workaround */
case ARM_CPU_PART_CORTEX_A57:
case ARM_CPU_PART_CORTEX_A72: {
struct arm_smccc_res res;
state = spectre_v2_get_cpu_fw_mitigation_state();
if (state != SPECTRE_MITIGATED)
break;
if (psci_ops.smccc_version == SMCCC_VERSION_1_0)
break;
switch (psci_ops.conduit) {
case PSCI_CONDUIT_HVC:
arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
ARM_SMCCC_ARCH_WORKAROUND_1, &res);
if ((int)res.a0 != 0)
break;
method = SPECTRE_V2_METHOD_HVC;
break;
case PSCI_CONDUIT_SMC:
arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
ARM_SMCCC_ARCH_WORKAROUND_1, &res);
if ((int)res.a0 != 0)
break;
method = SPECTRE_V2_METHOD_SMC;
break;
default:
state = SPECTRE_VULNERABLE;
break;
}
}
}
if (state == SPECTRE_MITIGATED)
state = spectre_v2_install_workaround(method);
spectre_v2_update_state(state, method);
}
#ifdef CONFIG_HARDEN_BRANCH_HISTORY
static int spectre_bhb_method;
static const char *spectre_bhb_method_name(int method)
{
switch (method) {
case SPECTRE_V2_METHOD_LOOP8:
return "loop";
case SPECTRE_V2_METHOD_BPIALL:
return "BPIALL";
default:
return "unknown";
}
}
static int spectre_bhb_install_workaround(int method)
{
if (spectre_bhb_method != method) {
if (spectre_bhb_method) {
pr_err("CPU%u: Spectre BHB: method disagreement, system vulnerable\n",
smp_processor_id());
return SPECTRE_VULNERABLE;
}
if (spectre_bhb_update_vectors(method) == SPECTRE_VULNERABLE)
return SPECTRE_VULNERABLE;
spectre_bhb_method = method;
pr_info("CPU%u: Spectre BHB: enabling %s workaround for all CPUs\n",
smp_processor_id(), spectre_bhb_method_name(method));
}
return SPECTRE_MITIGATED;
}
#else
static int spectre_bhb_install_workaround(int method)
{
return SPECTRE_VULNERABLE;
}
#endif
static void cpu_v7_spectre_bhb_init(void)
{
unsigned int state, method = 0;
switch (read_cpuid_part()) {
case ARM_CPU_PART_CORTEX_A15:
case ARM_CPU_PART_BRAHMA_B15:
case ARM_CPU_PART_CORTEX_A57:
case ARM_CPU_PART_CORTEX_A72:
state = SPECTRE_MITIGATED;
method = SPECTRE_V2_METHOD_LOOP8;
break;
case ARM_CPU_PART_CORTEX_A73:
case ARM_CPU_PART_CORTEX_A75:
state = SPECTRE_MITIGATED;
method = SPECTRE_V2_METHOD_BPIALL;
break;
default:
state = SPECTRE_UNAFFECTED;
break;
}
if (state == SPECTRE_MITIGATED)
state = spectre_bhb_install_workaround(method);
spectre_v2_update_state(state, method);
}
static __maybe_unused bool cpu_v7_check_auxcr_set(bool *warned,
u32 mask, const char *msg)
{
u32 aux_cr;
asm("mrc p15, 0, %0, c1, c0, 1" : "=r" (aux_cr));
if ((aux_cr & mask) != mask) {
if (!*warned)
pr_err("CPU%u: %s", smp_processor_id(), msg);
*warned = true;
return false;
}
return true;
}
static DEFINE_PER_CPU(bool, spectre_warned);
static bool check_spectre_auxcr(bool *warned, u32 bit)
{
return IS_ENABLED(CONFIG_HARDEN_BRANCH_PREDICTOR) &&
cpu_v7_check_auxcr_set(warned, bit,
"Spectre v2: firmware did not set auxiliary control register IBE bit, system vulnerable\n");
}
void cpu_v7_ca8_ibe(void)
{
if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(6)))
cpu_v7_spectre_v2_init();
}
void cpu_v7_ca15_ibe(void)
{
if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(0)))
cpu_v7_spectre_v2_init();
cpu_v7_spectre_bhb_init();
}
void cpu_v7_bugs_init(void)
{
cpu_v7_spectre_v2_init();
cpu_v7_spectre_bhb_init();
}
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