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// SPDX-License-Identifier: GPL-2.0
#include <linux/arm-smccc.h>
#include <linux/kernel.h>
#include <linux/smp.h>
#include <asm/cp15.h>
#include <asm/cputype.h>
#include <asm/proc-fns.h>
#include <asm/system_misc.h>
#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 void cpu_v7_spectre_init(void)
{
const char *spectre_v2_method = NULL;
int cpu = smp_processor_id();
if (per_cpu(harden_branch_predictor_fn, cpu))
return;
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:
per_cpu(harden_branch_predictor_fn, cpu) =
harden_branch_predictor_bpiall;
spectre_v2_method = "BPIALL";
break;
case ARM_CPU_PART_CORTEX_A15:
case ARM_CPU_PART_BRAHMA_B15:
per_cpu(harden_branch_predictor_fn, cpu) =
harden_branch_predictor_iciallu;
spectre_v2_method = "ICIALLU";
break;
#ifdef CONFIG_ARM_PSCI
case ARM_CPU_PART_BRAHMA_B53:
/* Requires no workaround */
break;
default:
/* Other ARM CPUs require no workaround */
if (read_cpuid_implementor() == ARM_CPU_IMP_ARM)
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;
arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
ARM_SMCCC_ARCH_WORKAROUND_1, &res);
if ((int)res.a0 != 0)
return;
switch (arm_smccc_1_1_get_conduit()) {
case SMCCC_CONDUIT_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 SMCCC_CONDUIT_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;
default:
break;
}
}
#endif
}
if (spectre_v2_method)
pr_info("CPU%u: Spectre v2: using %s workaround\n",
smp_processor_id(), spectre_v2_method);
}
#else
static void cpu_v7_spectre_init(void)
{
}
#endif
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_init();
}
void cpu_v7_ca15_ibe(void)
{
if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(0)))
cpu_v7_spectre_init();
}
void cpu_v7_bugs_init(void)
{
cpu_v7_spectre_init();
}
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