Combined D31538 and D31539 plus some more
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Authored by kib on Aug 15 2021, 2:45 AM.

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fbsd-phab_maskray.me
emaste
bdragon

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rG300e08933e80: libc tls: use TLS_DTV_OFFSET defined by rtld.h

Summary

This is a diff from the branch where I am preparing listed revisions for the commit.

I do not like TLS_BELOW_TP symbol, instead I moved TLS_VARIANT_I/II from libc into rtld_machdep.h and use that.
Also I fixed style issues and converted libc to use TLS_DTV_OFFSET as well.

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rG FreeBSD src repository

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kib created this revision.Aug 15 2021, 2:45 AM

Herald added a subscriber: andrew. · View Herald TranscriptAug 15 2021, 2:45 AM

kib requested review of this revision.Aug 15 2021, 2:45 AM

FWIW TLS_BELOW_TP and TLS_ABOVE_TP are more descriptive. VARIANT_I and VARIANT_II are less clear. In addition, technically arm/aarch64 are not strict Variant I because of the 2 reserved words. mips/powerpc are not strict Variant I because of a non-zero DTP offset. FreeBSD doesn't support the strict Variant I architectures (e.g. Alpha, ia64)

In D31541#711138, @fbsd-phab_maskray.me wrote:

FWIW TLS_BELOW_TP and TLS_ABOVE_TP are more descriptive. VARIANT_I and VARIANT_II are less clear. In addition, technically arm/aarch64 are not strict Variant I because of the 2 reserved words. mips/powerpc are not strict Variant I because of a non-zero DTP offset. FreeBSD doesn't support the strict Variant I architectures (e.g. Alpha, ia64)

They should be clear for anybody touching TLS code. Main point is that rtld and static TLS in libc are becoming more aligned.

D31538 is a functional change. I think it'd be good not to fix functional change without unrelated cleanups.

In D31541#711153, @fbsd-phab_maskray.me wrote:

D31538 is a functional change. I think it'd be good not to fix functional change without unrelated cleanups.

This is how the topic branch looks like https://kib.kiev.ua/git/gitweb.cgi?p=deviant3.git;a=shortlog;h=refs/heads/rtld

This revision was not accepted when it landed; it landed in state Needs Review.Aug 16 2021, 10:56 AM

Closed by commit rG300e08933e80: libc tls: use TLS_DTV_OFFSET defined by rtld.h (authored by kib). · Explain Why

This revision was automatically updated to reflect the committed changes.

kib mentioned this in rGe6c769620316: rtld: Fix i386/amd64 TP offset when p_vaddr % p_align != 0.

kib mentioned this in rG8f63fa78e84a: rtld: Remove calculate_tls_end.

kib added a commit: rG300e08933e80: libc tls: use TLS_DTV_OFFSET defined by rtld.h.

Thanks:)