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>

diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index 1d57605..16f1e4f 100644 (file)
--- 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;