Re: [PATCH 2/2] MIPS: kernel: signal: Drop unused arguments for traditional signal handlers

[Markos Chandras <Markos.Chandras@imgtec.com>]

On 08/21/2015 06:03 PM, David Daney wrote:
> On 08/20/2015 04:45 AM, Markos Chandras wrote:
>> Traditional signal handlers (ie !SA_SIGINFO) only need only argument
>> holding the signal number so we drop the additional arguments and fix
>> the related comments. We also update the comments for the SA_SIGINFO
>> case where the second argument is a pointer to a siginfo_t structure.
>>
>> Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
>> ---
>>   arch/mips/kernel/signal.c     | 6 +-----
>>   arch/mips/kernel/signal32.c   | 6 +-----
>>   arch/mips/kernel/signal_n32.c | 2 +-
>>   3 files changed, 3 insertions(+), 11 deletions(-)
>>
>> diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
>> index be3ac5f7cbbb..3a125331bf8b 100644
>> --- a/arch/mips/kernel/signal.c
>> +++ b/arch/mips/kernel/signal.c
>> @@ -683,15 +683,11 @@ static int setup_frame(void *sig_return, struct
>> ksignal *ksig,
>>        * Arguments to signal handler:
>>        *
>>        *   a0 = signal number
>> -     *   a1 = 0 (should be cause)
>> -     *   a2 = pointer to struct sigcontext
>>        *
>>        * $25 and c0_epc point to the signal handler, $29 points to the
>>        * struct sigframe.
>>        */
>>       regs->regs[ 4] = ksig->sig;
>> -    regs->regs[ 5] = 0;
>> -    regs->regs[ 6] = (unsigned long) &frame->sf_sc;
> 
> This changes the kernel ABI.
> 
> Have you tested this change against all userspace applications that use
> signals to make sure it doesn't break anything?
> 
> David Daney

i am confident there is no userland application that uses inline asm to
fetch additional arguments from (*sa_handler) when using !SA_SIGINFO

-- 
markos