Re: [REVIEW][PATCH 14/22] signal/riscv: Use force_sig_fault where appropriate

[Eric W. Biederman]

Palmer Dabbelt <palmer@xxxxxxxxxx> writes:

> On Fri, 20 Apr 2018 07:38:03 PDT (-0700), ebiederm@xxxxxxxxxxxx wrote:
>> Filling in struct siginfo before calling force_sig_info a tedious and
>> error prone process, where once in a great while the wrong fields
>> are filled out, and siginfo has been inconsistently cleared.
>>
>> Simplify this process by using the helper force_sig_fault.  Which
>> takes as a parameters all of the information it needs, ensures
>> all of the fiddly bits of filling in struct siginfo are done properly
>> and then calls force_sig_info.
>>
>> In short about a 5 line reduction in code for every time force_sig_info
>> is called, which makes the calling function clearer.
>>
>> Cc: Palmer Dabbelt <palmer@xxxxxxxxxx>
>> Cc: Albert Ou <albert@xxxxxxxxxx>
>> Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx
>> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
>> ---
>>  arch/riscv/kernel/traps.c | 9 +--------
>>  1 file changed, 1 insertion(+), 8 deletions(-)
>>
>> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
>> index 48aa6471cede..3087940008f4 100644
>> --- a/arch/riscv/kernel/traps.c
>> +++ b/arch/riscv/kernel/traps.c
>> @@ -66,14 +66,7 @@ void die(struct pt_regs *regs, const char *str)
>>  static inline void do_trap_siginfo(int signo, int code,
>>  	unsigned long addr, struct task_struct *tsk)
>>  {
>> -	siginfo_t info;
>> -
>> -	clear_siginfo(&info);
>> -	info.si_signo = signo;
>> -	info.si_errno = 0;
>> -	info.si_code = code;
>> -	info.si_addr = (void __user *)addr;
>> -	force_sig_info(signo, &info, tsk);
>> +	force_sig_fault(signo, code, (void __user *)addr, tsk);
>>  }
>>
>>  void do_trap(struct pt_regs *regs, int signo, int code,
>
> If I understand this correctly, any change in behavior this causes would have
> been a bug on our end not filling out siginfo correctly?  In that case then feel
> free to add an

If this change above causes any user visible changes it is a bug.
As Christoph rightly pointed out force_sig_fault is simply the arch
generic version of do_trap_siginfo. 

Eric