MIPS: fix EVA & non-SMP non-FPU FP context signal handling

The save_fp_context & restore_fp_context pointers were being assigned
to the wrong variables if either:

  - The kernel is configured for UP & runs on a system without an FPU,
    since b2ead5282885 "MIPS: Move & rename
    fpu_emulator_{save,restore}_context".

  - The kernel is configured for EVA, since ca750649e08c "MIPS: kernel:
    signal: Prevent save/restore FPU context in user memory".

This would lead to FP context being clobbered incorrectly when setting
up a sigcontext, then the garbage values being saved uselessly when
returning from the signal.

Fix by swapping the pointer assignments appropriately.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: stable@vger.kernel.org # v3.15+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8230/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index 1d57605e4615..16f1e4f2bf3c 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -658,13 +658,13 @@ static int signal_setup(void)
                 save_fp_context = _save_fp_context;
                 restore_fp_context = _restore_fp_context;
         } else {
-                save_fp_context = copy_fp_from_sigcontext;
-                restore_fp_context = copy_fp_to_sigcontext;
+                save_fp_context = copy_fp_to_sigcontext;
+                restore_fp_context = copy_fp_from_sigcontext;
         }
 #endif /* CONFIG_SMP */
 #else
-        save_fp_context = copy_fp_from_sigcontext;;
-        restore_fp_context = copy_fp_to_sigcontext;
+        save_fp_context = copy_fp_to_sigcontext;
+        restore_fp_context = copy_fp_from_sigcontext;
 #endif
 
         return 0;