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Differential D13838

Implement ifunc support for x86, use it to enable SMAP on amd64.
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Authored by kib on Jan 10 2018, 9:25 PM.
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emaste
jhb
Commits
rS336876: Use SMAP on amd64.
rS333461: Make fpusave() and fpurestore() on amd64 ifuncs.
rS333229: Add helper macros to hide some boring repeatable ceremonies to define
rS333228: Implement support for ifuncs in the kernel linker.
rS333208: Style.
rS327965: Add STAC and CLAC instructions wrappers.
rS327822: Skip IRELATIVE relocations when loader processes ELF files.
rS327819: Do not clear %RFLAGS.DF on fast syscall entry.

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Event Timeline

kib created this revision.Jan 10 2018, 9:25 PM
Herald added subscribers: rpokala, imp. · View Herald TranscriptJan 10 2018, 9:25 PM
jhb accepted this revision.Jan 10 2018, 9:48 PM
jhb added a subscriber: jhb.

In general this looks ok to me. As we discussed on IRC I think it would be useful to split up into multiple commits. (e.g. ifunc, fpu/npx usage, pmap usage, fast_syscall changes that don't use SMAP (remove cld and shared function), and then SMAP itself).

sys/amd64/amd64/support.S
299 ↗(On Diff #37756)

I wonder if this comment is a bit stale? It doesn't seem like any pre-486 CPUs will ever support SMAP. OTOH, I'm not quite sure what is even meant by "486 write protection".

377 ↗(On Diff #37756)

(I know this is old code, but I wonder if this 'cld' is even needed anymore since 'cld' is now part of the ABI?)

sys/amd64/ia32/ia32_exception.S
70 ↗(On Diff #37756)

Picking one at random. Is there a reason to think that pushf/andl/popf is better than 'cld/clac'?

Ah to answer my own question (and for future readers): clac may not be supported on all processors but this pattern is.

sys/amd64/include/asmacros.h
182 ↗(On Diff #37756)

Perhaps go ahead and break these out on separate lines since all the other instructions are on separate lines?

sys/amd64/include/cpufunc.h
840 ↗(On Diff #37756)

s/slac/stac/? (I don't think this is used in any C code though as it wouldn't compile if so?)

This revision is now accepted and ready to land.Jan 10 2018, 9:48 PM
danilo added a subscriber: danilo.Jan 11 2018, 3:26 AM
kbowling added a subscriber: kbowling.Jan 11 2018, 4:16 AM
kib added inline comments.Jan 11 2018, 12:23 PM
sys/amd64/amd64/support.S
299 ↗(On Diff #37756)

As discussed, 'the protection' means CR0.WP=1.

In fact this comment is wrong in more fundamental way. The lack of CoW when user tricked copyout to copy into KVA is the least of the problems. I rewrote it there and for i386.

If CR0,WP=0, CoW would not work anyway, checked or not.

Closed by commit rS327819: Do not clear %RFLAGS.DF on fast syscall entry. (authored by kib). · Explain WhyJan 11 2018, 12:54 PM
This revision was automatically updated to reflect the committed changes.
kib updated this revision to Diff 37793.Jan 11 2018, 1:23 PM

Re-merge the branch.

kib reopened this revision.Jan 11 2018, 1:24 PM
kib updated this revision to Diff 37795.Jan 11 2018, 1:27 PM

Fix typo slac->stac.

Noted by: jhb

kib updated this revision to Diff 37796.Jan 11 2018, 1:42 PM

Fix one more merge conflict.

This revision was not accepted when it landed; it landed in state Needs Review.Jan 11 2018, 1:57 PM
Closed by commit rS327822: Skip IRELATIVE relocations when loader processes ELF files. (authored by kib). · Explain Why
This revision was automatically updated to reflect the committed changes.
kib reopened this revision.Jan 11 2018, 2:00 PM
kib updated this revision to Diff 37799.

re-merge

This revision was not accepted when it landed; it landed in state Needs Review.Jan 14 2018, 12:40 PM
Closed by commit rS327965: Add STAC and CLAC instructions wrappers. (authored by kib). · Explain Why
This revision was automatically updated to reflect the committed changes.
kib reopened this revision.Jan 14 2018, 12:42 PM
kib updated this revision to Diff 37934.

Re-merge.

dch added a subscriber: dch.Jan 14 2018, 12:46 PM
op added a subscriber: op.Jan 21 2018, 12:48 AM
lffpires_ruabrasil.org added a subscriber: lffpires_ruabrasil.org.Apr 11 2018, 9:07 PM
This revision was not accepted when it landed; it landed in state Needs Review.May 3 2018, 10:17 AM
Closed by commit rS333208: Style. (authored by kib). · Explain Why
This revision was automatically updated to reflect the committed changes.
kib reopened this revision.May 3 2018, 10:26 AM
kib updated this revision to Diff 42091.May 3 2018, 12:00 PM

Update after merge.

This revision was not accepted when it landed; it landed in state Needs Review.May 3 2018, 9:38 PM
Closed by commit rS333228: Implement support for ifuncs in the kernel linker. (authored by kib). · Explain Why
This revision was automatically updated to reflect the committed changes.
kib reopened this revision.May 3 2018, 9:50 PM
kib updated this revision to Diff 42113.May 3 2018, 9:53 PM

Rebase after commits.

Now the patch only contains the actual uses of ifuncs.

lattera-gmail.com added a subscriber: lattera-gmail.com.May 6 2018, 4:16 AM
This revision was not accepted when it landed; it landed in state Needs Review.May 10 2018, 3:02 PM
Closed by commit rS333461: Make fpusave() and fpurestore() on amd64 ifuncs. (authored by kib). · Explain Why
This revision was automatically updated to reflect the committed changes.
kib reopened this revision.May 10 2018, 3:03 PM
kib updated this revision to Diff 42363.May 10 2018, 3:06 PM

Update after amd64/fpu.c commit.

This revision was not accepted when it landed; it landed in state Needs Review.Jul 29 2018, 8:47 PM
Closed by commit rS336876: Use SMAP on amd64. (authored by kib). · Explain Why
This revision was automatically updated to reflect the committed changes.

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sys/
amd64/
include/
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Diff 37933

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head/sys/amd64/include/cpufunc.h

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