Reserve WXNEEDED ELF feature control flag
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Authored by emaste on Mar 1 2020, 9:24 PM.

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csjp
markj
kib

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rS358631: Reserve WXNEEDED ELF feature control flag

Summary

This will be used to tag binaries that require W+X mappings.

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rS FreeBSD src repository - subversion

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emaste created this revision.Mar 1 2020, 9:24 PM

Looks perfectly reasonable to me.

This revision is now accepted and ready to land.Mar 1 2020, 9:44 PM

emaste added a subscriber: kib.Mar 3 2020, 4:09 PM

All other flags are called 'disabled'. It takes some efforts to realize that this flag also disables some feature.

I prefer that we tag the binaries with statements of fact (this binary makes W+X mappings) rather than demand policy decisions (turn off W^X mode), although for all existing cases it's not easy to succinctly state the fact. The other argument for wxneeded is that this is what the flag is already called by OpenBSD, and supported by lld there (as -z wxneeded). I'm also not sure the disable form (i.e., NT_FREEBSD_FCTL_DISABLE_WXORX) is more clear.

However this sort of discussion is the reason I posted it for review first, let's see what folks think.

Ok, commit whatever name you have now to have the bit reserved. Changing the name does not change ABI.

Closed by commit rS358631: Reserve WXNEEDED ELF feature control flag (authored by emaste). · Explain WhyMar 4 2020, 6:21 PM

This revision was automatically updated to reflect the committed changes.

emaste added a commit: rS358631: Reserve WXNEEDED ELF feature control flag.

Herald added a subscriber: imp. · View Herald TranscriptMar 4 2020, 6:21 PM

dim mentioned this in rS367462: Sync up elftoolchain with head, except for the capsicum-related commits,.Nov 7 2020, 7:55 PM

dim mentioned this in rS367466: Sync up elftoolchain with head, except for the capsicum-related commits,.Nov 7 2020, 11:58 PM