diff options
Diffstat (limited to 'arch/arm64/kernel/proton-pack.c')
-rw-r--r-- | arch/arm64/kernel/proton-pack.c | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c index 4f1411b45301..b373e4782ccd 100644 --- a/arch/arm64/kernel/proton-pack.c +++ b/arch/arm64/kernel/proton-pack.c @@ -20,6 +20,7 @@ #include <linux/arm-smccc.h> #include <linux/cpu.h> #include <linux/device.h> +#include <linux/nospec.h> #include <linux/prctl.h> #include <asm/spectre.h> @@ -318,3 +319,120 @@ void spectre_v2_enable_mitigation(const struct arm64_cpu_capabilities *__unused) update_mitigation_state(&spectre_v2_state, state); } + +/* Spectre v4 prctl */ +static void ssbd_ssbs_enable(struct task_struct *task) +{ + u64 val = is_compat_thread(task_thread_info(task)) ? + PSR_AA32_SSBS_BIT : PSR_SSBS_BIT; + + task_pt_regs(task)->pstate |= val; +} + +static void ssbd_ssbs_disable(struct task_struct *task) +{ + u64 val = is_compat_thread(task_thread_info(task)) ? + PSR_AA32_SSBS_BIT : PSR_SSBS_BIT; + + task_pt_regs(task)->pstate &= ~val; +} + +/* + * prctl interface for SSBD + */ +static int ssbd_prctl_set(struct task_struct *task, unsigned long ctrl) +{ + int state = arm64_get_ssbd_state(); + + /* Unsupported */ + if (state == ARM64_SSBD_UNKNOWN) + return -ENODEV; + + /* Treat the unaffected/mitigated state separately */ + if (state == ARM64_SSBD_MITIGATED) { + switch (ctrl) { + case PR_SPEC_ENABLE: + return -EPERM; + case PR_SPEC_DISABLE: + case PR_SPEC_FORCE_DISABLE: + return 0; + } + } + + /* + * Things are a bit backward here: the arm64 internal API + * *enables the mitigation* when the userspace API *disables + * speculation*. So much fun. + */ + switch (ctrl) { + case PR_SPEC_ENABLE: + /* If speculation is force disabled, enable is not allowed */ + if (state == ARM64_SSBD_FORCE_ENABLE || + task_spec_ssb_force_disable(task)) + return -EPERM; + task_clear_spec_ssb_disable(task); + clear_tsk_thread_flag(task, TIF_SSBD); + ssbd_ssbs_enable(task); + break; + case PR_SPEC_DISABLE: + if (state == ARM64_SSBD_FORCE_DISABLE) + return -EPERM; + task_set_spec_ssb_disable(task); + set_tsk_thread_flag(task, TIF_SSBD); + ssbd_ssbs_disable(task); + break; + case PR_SPEC_FORCE_DISABLE: + if (state == ARM64_SSBD_FORCE_DISABLE) + return -EPERM; + task_set_spec_ssb_disable(task); + task_set_spec_ssb_force_disable(task); + set_tsk_thread_flag(task, TIF_SSBD); + ssbd_ssbs_disable(task); + break; + default: + return -ERANGE; + } + + return 0; +} + +int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which, + unsigned long ctrl) +{ + switch (which) { + case PR_SPEC_STORE_BYPASS: + return ssbd_prctl_set(task, ctrl); + default: + return -ENODEV; + } +} + +static int ssbd_prctl_get(struct task_struct *task) +{ + switch (arm64_get_ssbd_state()) { + case ARM64_SSBD_UNKNOWN: + return -ENODEV; + case ARM64_SSBD_FORCE_ENABLE: + return PR_SPEC_DISABLE; + case ARM64_SSBD_KERNEL: + if (task_spec_ssb_force_disable(task)) + return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE; + if (task_spec_ssb_disable(task)) + return PR_SPEC_PRCTL | PR_SPEC_DISABLE; + return PR_SPEC_PRCTL | PR_SPEC_ENABLE; + case ARM64_SSBD_FORCE_DISABLE: + return PR_SPEC_ENABLE; + default: + return PR_SPEC_NOT_AFFECTED; + } +} + +int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which) +{ + switch (which) { + case PR_SPEC_STORE_BYPASS: + return ssbd_prctl_get(task); + default: + return -ENODEV; + } +} |