在 2020/5/25 下午4:42, Thomas Bogendoerfer 写道:
> On Mon, May 25, 2020 at 11:31:23AM +0800, YuanJunQing wrote:
>> 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
> do we realy need to read fcr31 that early ? Wouldn't it work to
> just move the cfc1 below TRACE_IRQS_OFF ?
>
> Thomas.
yes, it can work when we just move the cfc1 below TRACE_IRQS_OFF,
and the code is written as follows.
CLI
TRACE_IRQS_OFF
.set mips1
SET_HARDFLOAT
cfc1 a1, fcr31
.set pop
.endm
