csu: Find the main pointer through the GOT
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Authored by andrew on Mon, May 20, 11:59 AM.

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Reviewers

brooks
imp
emaste
jhb
jrtc27

Group Reviewers

arm64

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rG53120fbb6895: csu: Find the main pointer through the GOT

Summary

Use the Global Offset Table to find the location of main in crt1. With
lld the old code would point to main@plt, however ld.bfd fails to link
when main is in a shared library.

Fix this by using the GOT address to find main as it works with both
lld and bfd.

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Repository

rG FreeBSD src repository

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Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

andrew requested review of this revision.Mon, May 20, 11:59 AM

andrew created this revision.

andrew added a parent revision: D45258: stand/kboot: Fix the linker script OUTPUT_FORMAT.

andrew added a child revision: D45260: sys/sys: Fix __builtin_is_aligned fallback.

Harbormaster completed remote builds in B57773: Diff 138760.Mon, May 20, 12:01 PM

jhb added a reviewer: jrtc27.Mon, May 20, 5:23 PM

It surprises me that GNU ld doesn't want to create canonical PLTs, but avoiding them is reasonable; they are to functions what copy relocations are to data.

Putting main in a shared library sounds particularly cursed, but I guess it's not uncommon for testing frameworks. Presumably this is for libgtest_main.

This revision is now accepted and ready to land.Mon, May 20, 5:32 PM

It was for something in the Google testing bits.

Closed by commit rG53120fbb6895: csu: Find the main pointer through the GOT (authored by andrew). · Explain WhyWed, May 22, 8:33 AM

This revision was automatically updated to reflect the committed changes.

andrew added a commit: rG53120fbb6895: csu: Find the main pointer through the GOT.