+#define X87_FSW_ES (1 << 7) /* Exception Summary */
+
+/* AMD CPUs don't save/restore FDP/FIP/FOP unless an exception
+ is pending. Clear the x87 state here by setting it to fixed
+ values. The kernel data segment can be sometimes 0 and sometimes
+ new user value. Both should be ok.
+ Use the PDA as safe address because it should be already in L1. */
+static inline void clear_fpu_state(struct i387_fxsave_struct *fx)
+{
+ if (unlikely(fx->swd & X87_FSW_ES))
+ asm volatile("fnclex");
+ alternative_input(ASM_NOP8 ASM_NOP2,
+ " emms\n" /* clear stack tags */
+ " fildl %%gs:0", /* load to clear state */
+ X86_FEATURE_FXSAVE_LEAK);
+}
+