code review 10271047: cmd/5l,runtime: External linking support on linux-arm

cmd/5l,runtime: External linking support on linux-arm

This CL adds support for -linkmode external to 5l.

For 5l itself, use addrel to allow for D_CALL relocations to be handled by the host linker. Of the cases listed in rsc's comment in issue 4069, only case 5 and 63 needed an update. One of the TODO: addrel cases was since replaced, and the rest of the cases are either covered by indirection through addpool (cases with LTO or LFROM flags) or stubs (case 74). The addpool cases are covered because addpool emits AWORD instructions, which in turn are handled by case 11.

In the runtime, change the argv argument in the rt0* functions slightly to be a pointer to the argv list, instead of relying on a particular location of argv.

Depends on CL 10499043

Fixes issue 5590.

[elias.naur, 2013-06-14 15:40:51]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://go.googlecode.com/hg/

[elias.naur, 2013-07-04 10:01:09]

ping.

[rsc, 2013-08-13 19:05:49]

LGTM

I will submit this tonight after testing on my ARM Chromebook.

https://codereview.appspot.com/10271047/diff/23001/src/pkg/runtime/rt0_linux_...
File src/pkg/runtime/rt0_linux_arm.s (right):

https://codereview.appspot.com/10271047/diff/23001/src/pkg/runtime/rt0_linux_...
src/pkg/runtime/rt0_linux_arm.s:83: TEXT main(SB),NOSPLIT,$-8
$-8 doesnt mean what you think it means. should be $-4.

[elias.naur, 2013-08-13 22:09:19]

On 2013/08/13 19:05:49, rsc wrote:
> LGTM
> 
> I will submit this tonight after testing on my ARM Chromebook.
> 
>
https://codereview.appspot.com/10271047/diff/23001/src/pkg/runtime/rt0_linux_...
> File src/pkg/runtime/rt0_linux_arm.s (right):
> 
>
https://codereview.appspot.com/10271047/diff/23001/src/pkg/runtime/rt0_linux_...
> src/pkg/runtime/rt0_linux_arm.s:83: TEXT main(SB),NOSPLIT,$-8
> $-8 doesnt mean what you think it means. should be $-4.

Wonderful! Thanks for the review.

However, since this CL builds on 10499043 through hg mq I created this CL by
forcing codereview, and hg clpatch will probably complain on your side. We'll
have to do this in lockstep: When 10499043 is submitted, I'll update this CL
(including the $-4 fix) and when this is submitted I'll finally update 9733044
so it can be submitted last. I apologize for your inconvenience.

[elias.naur, 2013-08-14 07:06:18]

On 2013/08/13 22:09:19, elias.naur wrote:
> On 2013/08/13 19:05:49, rsc wrote:
> > LGTM
> > 
> > I will submit this tonight after testing on my ARM Chromebook.
> > 
> >
>
https://codereview.appspot.com/10271047/diff/23001/src/pkg/runtime/rt0_linux_...
> > File src/pkg/runtime/rt0_linux_arm.s (right):
> > 
> >
>
https://codereview.appspot.com/10271047/diff/23001/src/pkg/runtime/rt0_linux_...
> > src/pkg/runtime/rt0_linux_arm.s:83: TEXT main(SB),NOSPLIT,$-8
> > $-8 doesnt mean what you think it means. should be $-4.
> 
> Wonderful! Thanks for the review.
> 
> However, since this CL builds on 10499043 through hg mq I created this CL by
> forcing codereview, and hg clpatch will probably complain on your side. We'll
> have to do this in lockstep: When 10499043 is submitted, I'll update this CL
> (including the $-4 fix) and when this is submitted I'll finally update 9733044
> so it can be submitted last. I apologize for your inconvenience.

I also created a combined CL at https://codereview.appspot.com/12871044/ for
your convenience so you can test and/or submit from that.

[capnm, 2013-08-14 09:59:34]

On 2013/08/14 07:06:18, elias.naur wrote:
> On 2013/08/13 22:09:19, elias.naur wrote:
> > On 2013/08/13 19:05:49, rsc wrote:
> > > LGTM
> > > 
> > > I will submit this tonight after testing on my ARM Chromebook.
> > > 
> > >
> >
>
https://codereview.appspot.com/10271047/diff/23001/src/pkg/runtime/rt0_linux_...
> > > File src/pkg/runtime/rt0_linux_arm.s (right):
> > > 
> > >
> >
>
https://codereview.appspot.com/10271047/diff/23001/src/pkg/runtime/rt0_linux_...
> > > src/pkg/runtime/rt0_linux_arm.s:83: TEXT main(SB),NOSPLIT,$-8
> > > $-8 doesnt mean what you think it means. should be $-4.
> > 
> > Wonderful! Thanks for the review.
> > 
> > However, since this CL builds on 10499043 through hg mq I created this CL by
> > forcing codereview, and hg clpatch will probably complain on your side.
We'll
> > have to do this in lockstep: When 10499043 is submitted, I'll update this CL
> > (including the $-4 fix) and when this is submitted I'll finally update
9733044
> > so it can be submitted last. I apologize for your inconvenience.
> 
> I also created a combined CL at https://codereview.appspot.com/12871044/ for
> your convenience so you can test and/or submit from that.

Incredibly wonderful!
All tests passed (fa4c62bd1d41 tip + 12871044) on raspberry pi:
Linux rpi 3.6.11+ #474 PREEMPT Thu Jun 13 17:14:42 BST 2013 armv6l GNU/Linux

Also our tests (with external static linking) passed.

[rsc, 2013-09-03 19:06:41]

This was submitted as part of 12871044.