Re: [PATCH] Sanitize gdbarch access on probe/SDT API

[Sergio Durigan Junior <sergiodj at redhat dot com>]

On Friday, December 06 2013, Pedro Alves wrote:

> On 12/05/2013 10:12 PM, Sergio Durigan Junior wrote:
>> @@ -1461,6 +1466,8 @@ stap_get_probes (VEC (probe_p) **probesp, struct objfile *objfile)
>>    bfd_vma base;
>>    struct sdt_note *iter;
>>    unsigned save_probesp_len = VEC_length (probe_p, *probesp);
>> +  struct regcache *regcache = get_current_regcache ();
>> +  struct gdbarch *gdbarch = get_regcache_arch (regcache);
>
> AFAICS, stap_get_probes isn't called when evaluating a probe,
> but instead when getting the list of probes out of an objfile.

Right.

> Seems to me like this function is reachable even if the inferior
> is not running yet.  Is that why you couldn't use
> get_selected_frame here? (because there's no frame?)

Right.

> If so, using get_current_regcache is wrong.  If there's no thread at
> all, then what does the regcache of the current thread mean?

Indeed.  Now that you put it that way, it makes total sense.

> It sounds like you just managed to use it becauese
> get_current_regcache doesn't error out when inferior_ptid is pointing
> nowhere.

OK, interesting.

> As this is listing the probes in the objfile, and not using the
>target's registers (afaics), can you use the objfile's arch here?

Yes, I guess that's the best solution indeed.

> With that out of the way, would it work to pass the frame pointer down
>instead of the gdbarch?

You mean that the callers should pass the frame pointers, instead of the
relying on the callees to get it by themselves?

-- 
Sergio