+/*
+ * Some instructions like VIA's padlock instructions generate a spurious
+ * DNA fault but don't modify SSE registers. And these instructions
+ * get used from interrupt context aswell. To prevent these kernel instructions
+ * in interrupt context interact wrongly with other user/kernel fpu usage, we
+ * should use them only in the context of irq_ts_save/restore()
+ */
+static inline int irq_ts_save(void)
+{
+ /*
+ * If we are in process context, we are ok to take a spurious DNA fault.
+ * Otherwise, doing clts() in process context require pre-emption to
+ * be disabled or some heavy lifting like kernel_fpu_begin()
+ */
+ if (!in_interrupt())
+ return 0;
+
+ if (read_cr0() & X86_CR0_TS) {
+ clts();
+ return 1;
+ }
+
+ return 0;
+}
+
+static inline void irq_ts_restore(int TS_state)
+{
+ if (TS_state)
+ stts();
+}
+