Re: [PATCH 7/7] DWARF: add the config option

From	"H. Peter Anvin" <hpa@zytor.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 7/7] DWARF: add the config option
Date	2017-05-22 23:50 +0200
Message-ID	<tK3nb-2zS-11@gated-at.bofh.it> (permalink)
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On 05/22/17 14:07, H. Peter Anvin wrote:
> On 05/20/17 13:01, H.J. Lu wrote:
>> On Sat, May 20, 2017 at 9:20 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>>
>>>>
>>>> (H.J., could we get a binutils feature that allows is to do:
>>>>
>>>> pushq %whatever
>>>> .cfi_adjust_sp -8
>>>> ...
>>>> popq %whatever
>>>> .cfi_adjust_sp 8
>>>>
>>
>> Np.  Compiler needs to generate this.
>>
> 
> For actual assembly we have such a feature, it is called macros.
> 
> push/pop is the easy stuff; macros take care of that, but the real pain
> is dealing with the flow of control.
> 

My biggest beef with the CFI directives that gas uses is that there is
that .cfi_remember_state/.cfi_restore_state doesn't have a way to
specify more than one state.  That makes it really hard to get sanity
around control flow changes, especially with code that is intentionally
out of line.

That, and some of the CFI directives seem to be a bit ill-defined in
their definition (are they even applicable to anything other than
DWARF?)  They almost seem to be referencing some external specification,
but the only thing I'm finding is the DWARF documentation which is
written in very different terms.

The best description of what a personality routine is I found in an
article by Ian Lance Taylor.  It doesn't seem to be applicable to C as
far as I can tell.

	-hpa

Thread

Re: [PATCH 7/7] DWARF: add the config option Josh Poimboeuf <jpoimboe@redhat.com> - 2017-05-19 23:00 +0200
  Re: [PATCH 7/7] DWARF: add the config option "H. Peter Anvin" <hpa@zytor.com> - 2017-05-19 23:10 +0200
    Re: [PATCH 7/7] DWARF: add the config option Josh Poimboeuf <jpoimboe@redhat.com> - 2017-05-19 23:30 +0200
      Re: [PATCH 7/7] DWARF: add the config option Josh Poimboeuf <jpoimboe@redhat.com> - 2017-05-19 23:40 +0200
        Re: [PATCH 7/7] DWARF: add the config option Andy Lutomirski <luto@kernel.org> - 2017-05-20 07:30 +0200
          Re: [PATCH 7/7] DWARF: add the config option Josh Poimboeuf <jpoimboe@redhat.com> - 2017-05-20 18:30 +0200
            Re: [PATCH 7/7] DWARF: add the config option Josh Poimboeuf <jpoimboe@redhat.com> - 2017-05-20 19:20 +0200
            Re: [PATCH 7/7] DWARF: add the config option "H.J. Lu" <hjl.tools@gmail.com> - 2017-05-20 22:10 +0200
              Re: [PATCH 7/7] DWARF: add the config option Andy Lutomirski <luto@kernel.org> - 2017-05-21 00:00 +0200
                Re: [PATCH 7/7] DWARF: add the config option "H.J. Lu" <hjl.tools@gmail.com> - 2017-05-21 00:30 +0200
                Re: [PATCH 7/7] DWARF: add the config option Jiri Kosina <jikos@kernel.org> - 2017-05-22 13:40 +0200
                Re: [PATCH 7/7] DWARF: add the config option "H.J. Lu" <hjl.tools@gmail.com> - 2017-05-22 16:50 +0200
              Re: [PATCH 7/7] DWARF: add the config option "H. Peter Anvin" <hpa@zytor.com> - 2017-05-22 23:20 +0200
                Re: [PATCH 7/7] DWARF: add the config option "H. Peter Anvin" <hpa@zytor.com> - 2017-05-22 23:50 +0200
                Re: [PATCH 7/7] DWARF: add the config option Josh Poimboeuf <jpoimboe@redhat.com> - 2017-05-23 00:20 +0200
          Re: [PATCH 7/7] DWARF: add the config option Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-20 22:20 +0200
            Re: [PATCH 7/7] DWARF: add the config option Andy Lutomirski <luto@kernel.org> - 2017-05-21 00:00 +0200
              Re: [PATCH 7/7] DWARF: add the config option Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-21 01:10 +0200
                Re: [PATCH 7/7] DWARF: add the config option Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-21 01:30 +0200
      Re: [PATCH 7/7] DWARF: add the config option Ingo Molnar <mingo@kernel.org> - 2017-05-22 13:20 +0200
        Re: [PATCH 7/7] DWARF: add the config option "H. Peter Anvin" <hpa@zytor.com> - 2017-05-22 23:30 +0200
          Re: [PATCH 7/7] DWARF: add the config option Jiri Kosina <jikos@kernel.org> - 2017-05-23 01:30 +0200
          Re: [PATCH 7/7] DWARF: add the config option Ingo Molnar <mingo@kernel.org> - 2017-05-23 07:50 +0200
  Re: [PATCH 7/7] DWARF: add the config option "H. Peter Anvin" <hpa@zytor.com> - 2017-05-19 23:10 +0200

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