unmap_shadow_stack(shstk->base, shstk->size);
}
+static int wrss_control(bool enable)
+{
+ u64 msrval;
+
+ if (!cpu_feature_enabled(X86_FEATURE_USER_SHSTK))
+ return -EOPNOTSUPP;
+
+ /*
+ * Only enable WRSS if shadow stack is enabled. If shadow stack is not
+ * enabled, WRSS will already be disabled, so don't bother clearing it
+ * when disabling.
+ */
+ if (!features_enabled(ARCH_SHSTK_SHSTK))
+ return -EPERM;
+
+ /* Already enabled/disabled? */
+ if (features_enabled(ARCH_SHSTK_WRSS) == enable)
+ return 0;
+
+ fpregs_lock_and_load();
+ rdmsrl(MSR_IA32_U_CET, msrval);
+
+ if (enable) {
+ features_set(ARCH_SHSTK_WRSS);
+ msrval |= CET_WRSS_EN;
+ } else {
+ features_clr(ARCH_SHSTK_WRSS);
+ if (!(msrval & CET_WRSS_EN))
+ goto unlock;
+
+ msrval &= ~CET_WRSS_EN;
+ }
+
+ wrmsrl(MSR_IA32_U_CET, msrval);
+
+unlock:
+ fpregs_unlock();
+
+ return 0;
+}
+
static int shstk_disable(void)
{
if (!cpu_feature_enabled(X86_FEATURE_USER_SHSTK))
fpregs_unlock();
shstk_free(current);
- features_clr(ARCH_SHSTK_SHSTK);
+ features_clr(ARCH_SHSTK_SHSTK | ARCH_SHSTK_WRSS);
return 0;
}