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Diffstat (limited to 'arch/arm64/kernel/proton-pack.c')
-rw-r--r--arch/arm64/kernel/proton-pack.c118
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;
+ }
+}