Commit 10115105 authored by Russell King's avatar Russell King
Browse files

ARM: spectre-v2: add firmware based hardening



Add firmware based hardening for cores that require more complex
handling in firmware.
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
Boot-tested-by: default avatarTony Lindgren <tony@atomide.com>
Reviewed-by: default avatarTony Lindgren <tony@atomide.com>
Reviewed-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent f5fe12b1
// 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/system_misc.h>
#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
DEFINE_PER_CPU(harden_branch_predictor_fn_t, harden_branch_predictor_fn);
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);
......@@ -19,6 +25,16 @@ 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;
......@@ -45,7 +61,51 @@ static void cpu_v7_spectre_init(void)
harden_branch_predictor_iciallu;
spectre_v2_method = "ICIALLU";
break;
#ifdef CONFIG_ARM_PSCI
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;
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;
per_cpu(harden_branch_predictor_fn, cpu) =
call_hvc_arch_workaround_1;
processor.switch_mm = cpu_v7_hvc_switch_mm;
spectre_v2_method = "hypervisor";
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;
per_cpu(harden_branch_predictor_fn, cpu) =
call_smc_arch_workaround_1;
processor.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);
......
......@@ -9,6 +9,7 @@
*
* This is the "shell" of the ARMv7 processor support.
*/
#include <linux/arm-smccc.h>
#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/assembler.h>
......@@ -93,6 +94,26 @@ ENTRY(cpu_v7_dcache_clean_area)
ret lr
ENDPROC(cpu_v7_dcache_clean_area)
#ifdef CONFIG_ARM_PSCI
.arch_extension sec
ENTRY(cpu_v7_smc_switch_mm)
stmfd sp!, {r0 - r3}
movw r0, #:lower16:ARM_SMCCC_ARCH_WORKAROUND_1
movt r0, #:upper16:ARM_SMCCC_ARCH_WORKAROUND_1
smc #0
ldmfd sp!, {r0 - r3}
b cpu_v7_switch_mm
ENDPROC(cpu_v7_smc_switch_mm)
.arch_extension virt
ENTRY(cpu_v7_hvc_switch_mm)
stmfd sp!, {r0 - r3}
movw r0, #:lower16:ARM_SMCCC_ARCH_WORKAROUND_1
movt r0, #:upper16:ARM_SMCCC_ARCH_WORKAROUND_1
hvc #0
ldmfd sp!, {r0 - r3}
b cpu_v7_switch_mm
ENDPROC(cpu_v7_smc_switch_mm)
#endif
ENTRY(cpu_v7_iciallu_switch_mm)
mov r3, #0
mcr p15, 0, r3, c7, c5, 0 @ ICIALLU
......
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