Working on -e trace

[haris iqbal]

2016-03-07 Md Haris Iqbal <haris.phnx at gmail.com>

* defs.h
* + define TRACE_SCHED 04000 / Trace scheduler-related syscalls /

* syscall.c (lookup_class)
* +    if (strcmp(s, "scheduler") == 0)
* +        return TRACE_SCHED;
* + define TSC TRACE_SCHED

* All syscallent.h files
* added TSC flag

Tested with -e trace=scheduler

On Thu, Mar 3, 2016 at 5:47 AM, Dmitry V. Levin <ldv at altlinux.org> wrote:
> On Wed, Mar 02, 2016 at 10:45:53AM +0530, haris iqbal wrote:
> [...]
>> A little help is needed here. I could understand that for the -e
>> option, one uses the combination of sysent_vec[][].sys_flags and the
>> macros TRACE_FILE and others, which sets the proper flag in qual_vec.
>> Now that qual_vec is used by qual_flg in the tcb struct (correct me if
>> something is wrong).
>>
>> But what I could not find is where those flag is used to print only
>> the syscalls that are needed (like only file related). I searched and
>> followed the flow of execution and found trace_syscall_entering()
>> through trace_syscall() in trace(). There is a function calles
>> get_scno(), I guess its where this syscall filtering is happening but
>> not sure. Can someone please point me in the right direction.
>
> tcp->qual_flg is initialized from qual_flags[tcp->scno] in get_scno()
> and later tested for QUAL_TRACE flag in trace_syscall_entering().
>
>> NOTE:
>>
>> 1) I am looking at the -e option closely to come up with a POC for the
>> idea "Fault injection for syscalls".
>>
>> 2) Waiting for a reply for the naming policy so that I can start
>> working to add the sched_* and the *uid *gid ones to the -e option.
>
> You can start with some naming policy, e.g. %sched, %uid, and %gid.
> I suppose a patch might attract more comments than a general discussion
> on the subject.
>
>
> --
> ldv
>
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-- 

With regards,

Md Haris Iqbal,
Placement Coordinator, MTech IT
NITK Surathkal,
Contact: +91 8861996962