Re: [PATCH] objtool: Fix memory leak in decode_instructions()

[Kamalesh Babulal]

On Thursday 19 October 2017 08:02 PM, Josh Poimboeuf wrote:
> On Thu, Oct 19, 2017 at 09:31:37AM -0500, Josh Poimboeuf wrote:
> > On Fri, Oct 13, 2017 at 11:20:58AM +0530, Kamalesh Babulal wrote:
> > > On Friday 13 October 2017 10:36 AM, Josh Poimboeuf wrote:
> > > > On Fri, Oct 13, 2017 at 10:14:36AM +0530, Kamalesh Babulal wrote:
> > > > > On Thursday 12 October 2017 09:40 PM, Josh Poimboeuf wrote:
> > > > > > On Thu, Oct 12, 2017 at 02:32:14PM +0530, Kamalesh Babulal wrote:
> > > > > > > free the allocated insn before returning, when an error occurs
> > > > > > > before adding insn to file->insn_list.
> > > > > > >
> > > > > > > Signed-off-by: Kamalesh Babulal <kamalesh@xxxxxxxxxxxxxxxxxx>
> > > > > >
> > > > > > Any chance you're working on porting objtool to ppc64le? :-)
> > > > > >
> > > > > > Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> > > > >
> > > > > Thanks for the review. I have started working on it :)
> > > >
> > > > Good!  Let me know if you have any questions.
> > >
> > > Thank you, I am sure I will have lots of them.
> > >
> > > > I originally wrote objtool with arch-independence in mind, though with
> > > > the new "objtool 2.0" rewrite, it unfortunately became more
> > > > x86-specific.
> > > >
> > > > I was hoping to work on making it more arch-independent, and then start
> > > > porting it to other arches, but it may be a few months before I have the
> > > > time to do so.  So any work you want to there would be great.
> > >
> > > Sure, will keep that in mind to abstract arch-independent code in to common
> > > files and push arch-dependent code into arch/ directory for both
> > > ppc64le/x86.
> >
> > Kamalesh, since you might be working on this soon, here's a bit of a
> > brain dump in case it helps.
> >
> > I have a vague idea for eventually improving objtool, which might make
> > arch-independence easier.  I wonder if we could use a GCC plugin to add
> > annotations in special sections, which are then read by objtool to help
> > it understand what's going on in the code.
> >
> > I suspect the plugins would need to be arch-specific.  But then maybe
> > that would allow objtool itself to be completely arch-independent.
> > Eventually, if we had similar clang plugins, objtool could become
> > compiler-independent as well.
> >
> > Unfortunately I haven't had a chance to think about it any more deeply
> > than that.  Just something to think about.
> >
> > Or maybe it makes sense to port objtool to ppc first, before trying to
> > abstract the arch-specific parts into plugins.  I dunno.

Thanks for sharing the thoughts on making objtool arch-independent.
I have not followed the discussions closely on GCC plugin to add
annotations/DWARF data. I will read through the ideas, before
commenting on them.


> > Also, another idea that has been suggested, is to use DWARF data as
> > input to objtool.  I have my doubts about that idea, but if it worked,
> > that might be another way to help objtool achieve arch-independence.
> >
> > For a previous discussion of these ideas, see:
> >
> >   https://lkml.kernel.org/r/20170831044209.4hodx2dasad66yab@treble
>
> Also, any chance you'll be in Prague for the conferences next week?  If
> so, we could discuss it more in person.

I will not be attending the conference.

--
cheers,
Kamalesh.