1 files changed, 35 insertions, 5 deletions

diff --git a/include/asm-x86/i387.h b/include/asm-x86/i387.h
index b1733601df95..1ecdc3ed96e4 100644
--- a/include/asm-x86/i387.h
+++ b/include/asm-x86/i387.h
@@ -7,12 +7,13 @@
  * x86-64 work by Andi Kleen 2002
  */
 
-#ifndef _ASM_X86_I387_H
-#define _ASM_X86_I387_H
+#ifndef ASM_X86__I387_H
+#define ASM_X86__I387_H
 
 #include <linux/sched.h>
 #include <linux/kernel_stat.h>
 #include <linux/regset.h>
+#include <linux/hardirq.h>
 #include <asm/asm.h>
 #include <asm/processor.h>
 #include <asm/sigcontext.h>
@@ -63,8 +64,6 @@ static inline int restore_fpu_checking(struct i387_fxsave_struct *fx)
 #else
                      : [fx] "cdaSDb" (fx), "m" (*fx), "0" (0));
 #endif
-        if (unlikely(err))
-                init_fpu(current);
         return err;
 }
 
@@ -237,6 +236,37 @@ static inline void kernel_fpu_end(void)
         preempt_enable();
 }
 
+/*
+ * 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();
+}
+
 #ifdef CONFIG_X86_64
 
 static inline void save_init_fpu(struct task_struct *tsk)
@@ -307,4 +337,4 @@ static inline unsigned short get_fpu_mxcsr(struct task_struct *tsk)
         }
 }
 
-#endif  /* _ASM_X86_I387_H */
+#endif /* ASM_X86__I387_H */