xtensa: fix a7 clobbering in coprocessor context load/store

commit 839769c35477d4acc2369e45000ca7b0b6af39a7 upstream.

Fast coprocessor exception handler saves a3..a6, but coprocessor context
load/store code uses a4..a7 as temporaries, potentially clobbering a7.
'Potentially' because coprocessor state load/store macros may not use
all four temporary registers (and neither FPU nor HiFi macros do).
Use a3..a6 as intended.

Cc: stable@vger.kernel.org
Fixes: c658eac628aa ("[XTENSA] Add support for configurable registers and coprocessors")
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/xtensa/kernel/coprocessor.S b/arch/xtensa/kernel/coprocessor.S
index 45cc0ae0af6f966ed778253b9624d46a783c2152..c7b9f12896f20a6870588cd50e9849e11c992dcf 100644 (file)
--- a/arch/xtensa/kernel/coprocessor.S
+++ b/arch/xtensa/kernel/coprocessor.S
@@ -29,7 +29,7 @@
        .if XTENSA_HAVE_COPROCESSOR(x);                                 \
                .align 4;                                               \
        .Lsave_cp_regs_cp##x:                                           \
-               xchal_cp##x##_store a2 a4 a5 a6 a7;                     \
+               xchal_cp##x##_store a2 a3 a4 a5 a6;                     \
                jx      a0;                                             \
        .endif
 
@@ -46,7 +46,7 @@
        .if XTENSA_HAVE_COPROCESSOR(x);                                 \
                .align 4;                                               \
        .Lload_cp_regs_cp##x:                                           \
-               xchal_cp##x##_load a2 a4 a5 a6 a7;                      \
+               xchal_cp##x##_load a2 a3 a4 a5 a6;                      \
                jx      a0;                                             \
        .endif