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Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings

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On Tue, Oct 11, 2016 at 10:08:12AM +0200, Arnd Bergmann wrote:
> On Monday, October 10, 2016 3:23:22 PM CEST Josh Poimboeuf wrote:
> > 
> > Thanks for reporting it.  It looks like 'mtune=atom' sometimes makes a
> > slight change to one of the stack frame setup instructions.  Instead of:
> > 
> >   move rsp, rbp
> > 
> > It sometimes does:
> > 
> >   lea (%rsp),%rbp
> > 
> > They're two different instructions, but they have the same result.  It's
> > an easy fix for objtool.  I'll post a patch soon.
> > 
> > 
> 
> Ah, good to hear. I've replaced my patch with yours in my randconfig
> tests now and will let you know if there are any other warnings on
> atom. I've done a few thousand x86 randconfig builds now and done private
> patches for all warnings I got (I previously had fixes only for the arm
> warnings). I found objtool warnings for a few files in some configurations
> that do not involve -mtune=atom, maybe you can also look at what
> is going on there as I have no idea for how to address them:
> 
> drivers/scsi/fnic/fnic_main.o: warning: objtool: fnic_log_q_error() falls through to next function fnic_handle_link_event()
> drivers/scsi/snic/snic_res.o: warning: objtool: .text: unexpected end of section
> drivers/infiniband/sw/rxe/rxe_comp.o: warning: objtool: rxe_completer()+0x2f3: sibling call from callable instruction with changed frame pointer
> drivers/infiniband/sw/rxe/rxe_resp.o: warning: objtool: rxe_responder()+0x10f: sibling call from callable instruction with changed frame pointer
> kernel/locking/rwsem.o: warning: objtool: down_write_killable()+0x16: call without frame pointer save/setup
> 
> I can provide additional information for reproducing them if it's
> not immediately obvious what the problems are.

I'm really surprised the 0-day bot didn't find these.  I was under the
impression that it continuously did a bunch of randconfigs.

Anyway, if you could send the configs for the warnings, that would be
very helpful.

I also happen to be working on a significant rewrite of objtool and
these configs will come in handy for making a regression suite.

-- 
Josh

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[PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2016-10-10 15:10 +0200
  Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2016-10-10 22:40 +0200
    Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2016-10-11 10:20 +0200
      Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2016-10-11 14:30 +0200
        Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2016-10-11 17:10 +0200
          Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2016-10-11 18:10 +0200
            Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Arnd Bergmann <arnd@arndb.de> - 2016-10-11 22:50 +0200
              Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Josh Poimboeuf <jpoimboe@redhat.com> - 2016-10-12 15:10 +0200
  [PATCH] objtool: support '-mtune=atom' stack frame setup instruction Josh Poimboeuf <jpoimboe@redhat.com> - 2016-10-11 04:00 +0200

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