[MIPS] Retry {save,restore}_fp_context if failed in atomic context.
The save_fp_context()/restore_fp_context() might sleep on accessing
user stack and therefore might lose FPU ownership in middle of them.
If these function failed due to "in_atomic" test in do_page_fault,
touch the sigcontext area in non-atomic context and retry these
save/restore operation.
This is a replacement of a (broken) fix which was titled "Allow CpU
exception in kernel partially".
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/signal-common.h b/arch/mips/kernel/signal-common.h
index 297dfcb..c0faabd 100644
--- a/arch/mips/kernel/signal-common.h
+++ b/arch/mips/kernel/signal-common.h
@@ -34,4 +34,13 @@
/* Check and clear pending FPU exceptions in saved CSR */
extern int fpcsr_pending(unsigned int __user *fpcsr);
+/* Make sure we will not lose FPU ownership */
+#ifdef CONFIG_PREEMPT
+#define lock_fpu_owner() preempt_disable()
+#define unlock_fpu_owner() preempt_enable()
+#else
+#define lock_fpu_owner() pagefault_disable()
+#define unlock_fpu_owner() pagefault_enable()
+#endif
+
#endif /* __SIGNAL_COMMON_H */