[PATCH] MIPS: Fix IRQ tracing when call handle_fpe()

[YuanJunQing]

 Register "a1" is unsaved in this function,
 when CONFIG_TRACE_IRQFLAGS is enabled,
 the TRACE_IRQS_OFF macro will call trace_hardirqs_off(),
 and this may change register "a1".
 The variment of register "a1" may send SIGFPE signal
 to task when call do_fpe(),and this may kill the task.

Signed-off-by: YuanJunQing <yuanjunqin...@163.com>
---
 arch/mips/kernel/genex.S | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
index 8236fb291e3f..956a76429773 100644
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -480,16 +480,18 @@ NESTED(nmi_handler, PT_SIZE, sp)
        /* gas fails to assemble cfc1 for some archs (octeon).*/ \
        .set    mips1
        SET_HARDFLOAT
-       cfc1    a1, fcr31
+       cfc1    s0, fcr31
        .set    pop
        CLI
        TRACE_IRQS_OFF
+       move    a1,s0
        .endm
 
        .macro  __build_clear_msa_fpe
-       _cfcmsa a1, MSA_CSR
+       _cfcmsa s0, MSA_CSR
        CLI
        TRACE_IRQS_OFF
+       move    a1,s0
        .endm
 
        .macro  __build_clear_ade
-- 
2.17.1