rtld-elf and libsys: remove old forward-compat code for powerpc auxv renumbering
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Authored by kib on Tue, Nov 18, 11:08 AM.

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tpearson_raptorengineering.com
brooks

Summary

This code was hackishly added in 2019 (__FreeBSD_version 1300070)
to provide the forward compatibility, allowing to somehow run newer
rtld on old kernel.

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rG FreeBSD src repository

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Event Timeline

kib created this revision.Tue, Nov 18, 11:08 AM

Herald added subscribers: bdragon, imp. · View Herald TranscriptTue, Nov 18, 11:08 AM

kib requested review of this revision.Tue, Nov 18, 11:08 AM

tpearson_raptorengineering.com added a subscriber: tpearson_raptorengineering.com.Tue, Nov 18, 5:15 PM

emaste added a subscriber: emaste.Tue, Nov 18, 5:27 PM

Stub all arches

Herald added a reviewer: andrew. · View Herald TranscriptWed, Nov 19, 2:04 AM

Herald added a reviewer: andrew. · View Herald Transcript

jhibbits added a subscriber: jhibbits.Wed, Nov 19, 2:04 AM

Looks good to me on a POWER9 Blackbird / powerpc64le.

Thanks for putting this together!

This revision is now accepted and ready to land.Wed, Nov 19, 4:13 AM

On second read through, caught a couple of code issues that don't affect functionality. Once those are fixed this looks good.

libexec/rtld-elf/powerpc/reloc.c
848 ↗	(On Diff #166727)	This variable seems to be dangling. Remove?
libexec/rtld-elf/powerpc64/reloc.c
745 ↗	(On Diff #166727)	This variable seems to be dangling. Remove?

This revision now requires changes to proceed.Wed, Nov 19, 4:18 AM

In D53801#1229337, @tpearson_raptorengineering.com wrote:

On second read through, caught a couple of code issues that don't affect functionality. Once those are fixed this looks good.

After thinking about this code some more, I realized that it probably should be removed altogether. Basically, it is there to allow to run newer binaries (rtld/libsys) on older (pre-AT_ renumbering) kernels. This was done in ~2019, and arguably outlived even the limited usefulness it had at the time of the commit.

kib updated this revision to Diff 166733.Wed, Nov 19, 5:59 AM

kib retitled this revision from rtld-elf: move powerpc-specific code out of rtld to rtld-elf and libsys: remove old forward-compat code for powerpc auxv renumbering.

kib edited the summary of this revision. (Show Details)

kib removed a reviewer: andrew.

kib added a reviewer: brooks.Wed, Nov 19, 8:33 AM