RE: [PATCH v1] Intel(R) MPX - Bound violation handling.

Tedeschi, Walfred
2015-12-16T15:21:33Z

Pedro,

We have found an interesting fact, changing the order the observer_notify_signal_recieved from about line 8170 to just before
Observer_notify_normal_stop. Allows the evaluation of the siginfo without the stop.

Looking at the code I could not see anything could harm there.

What do you think? Is moving that code a possibility?

Thanks and regards,
-Fred

-----Original Message-----
From: Tedeschi, Walfred
Sent: Tuesday, December 15, 2015 11:59 AM
To: Pedro Alves; Joel Brobecker
Cc: gdb-patches@sourceware.org
Subject: RE: [PATCH v1] Intel(R) MPX - Bound violation handling.

Pedro,

It comes from the infrun.c (validate_siginfo_access) .
The requirement is not running is not fulfilled. Also in the case that we execute a lookup_interval and ask for value_contents we trigger the same code.

What would be the suggestion here:
Additional function to be used internally in infrun or add a flag.

Thanks a lot for your comments and insights!
Best regards,
-Fred

-----Original Message-----
From: Pedro Alves [mailto:palves@redhat.com]
Sent: Monday, December 14, 2015 7:45 PM
To: Tedeschi, Walfred; Joel Brobecker
Cc: gdb-patches@sourceware.org
Subject: Re: [PATCH v1] Intel(R) MPX - Bound violation handling.

On 12/14/2015 05:43 PM, Tedeschi, Walfred wrote:
> Joel and Pedro,
>
> Thanks a lot for your feedback!
>
> I Could address most of the comments in here.
> An important one is still missing, namely this one:
>
>> +{
>> + long si_code;
>> + struct regcache *regcache = get_current_regcache ();
>> + struct gdbarch *gdbarch = get_regcache_arch (regcache);
>> +
>> + set_running (user_visible_resume_ptid (1), 0);
>
> This is the part that _really_ concerns me, not necessary because I think it's wrong (although, it is a big red flag for me), but because I don't understand why it's needed, and how it will affect things.
> (From Joel)
>> + si_code = parse_and_eval_long ("$_siginfo.si_code\n");
>
> During the debugging time I understood that inferior was stopped. Gdb is that was in the process to determine in which state the inferior was.
> In this sense I set the flag at this point to allow for the evaluation.

Where is the error thrown that required brute-forcing set_running away?
Can we try to find some other way to handle this? E.g., use something a bit lower level than parse_and_eval_long that bypasses the error? E.g., start from lookup_internalvar and then use type/value manipulation routines?

Thanks,
Pedro Alves

>
> I also looked in gdb for error handling while performing evaluations but did not find anything.
> I am considering that the way to proceed is to use TRY and CATCH blocks. Would you recommend that?
>
> Thanks and regards,
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