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Differential D22976

[PowerPC] Kernel 64-bit atomics emulation for PPC32
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Authored by bdragon on Dec 30 2019, 10:22 PM.
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Subscribers
alfredo
imp
luporl

Details

Reviewers
jhibbits
jeff
kevans
Commits
rG92a6b17e8ba0: [PowerPC] [MIPS] Implement 32-bit kernel emulation of atomic64 operations
rG639dfeb83124: Update FreeBSD SPL atomics
rS356308: [PowerPC] [MIPS] Implement 32-bit kernel emulation of atomic64 operations
Summary

Here is the kernel side of the 64-bit atomics emulation needed for D22827 and other optimizations.

jhibbits did the main work, this is just a cleanup and split to kernel-side only.

Tested on an iBook G4 with D22827 applied.

Test Plan
  • Excercise all atomics from a test module?

Diff Detail

Repository
rS FreeBSD src repository - subversion
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Unit
Tests Not Applicable

Event Timeline

bdragon created this revision.Dec 30 2019, 10:22 PM
Herald added subscribers: alfredo, luporl, imp. · View Herald TranscriptDec 30 2019, 10:22 PM
jhibbits added inline comments.Jan 2 2020, 5:43 PM
sys/kern/subr_atomic64.c
1 ↗(On Diff #66165)

Since this is being done only for powerpc, should this not be moved to sys/powerpc/powerpc instead?

sys/sys/_atomic64e.h
1 ↗(On Diff #66165)

Same as above for this. And then it could be moved into sys/powerpc/include/atomic.h even.

jeff added inline comments.Jan 2 2020, 6:09 PM
sys/sys/_atomic64e.h
1 ↗(On Diff #66165)

I think it's not unlikely that some other 32bit platform may find it useful.

jhibbits accepted this revision.Jan 2 2020, 6:48 PM

If it makes sense to move them to sys/powerpc later, we can do that.

sys/sys/_atomic64e.h
1 ↗(On Diff #66165)

I agree. But if none others will make use of them (I've heard mips32 is UP only, so would probably take a much different route for atomic64), it doesn't make sense to keep it generic.

But, I won't block the review on that.

This revision is now accepted and ready to land.Jan 2 2020, 6:48 PM
imp added a comment.Jan 2 2020, 7:01 PM

I'd add Kyle Evans to this review.
Mips32 does have SMP, but the specific core has 64bit atomics if anybody wants to revive it.

imp added inline comments.Jan 2 2020, 7:02 PM
sys/kern/subr_atomic64.c
1 ↗(On Diff #66165)

Kyle is working on this for mips32 too...

kevans added a reviewer: kevans.Jan 2 2020, 7:43 PM
kevans accepted this revision.Jan 2 2020, 7:49 PM

LGTM, added it to mips o32 with this diff: https://people.freebsd.org/~kevans/mips-atomic64.diff

kevans mentioned this in D22989: mips o32: provide 64-bit atomics.Jan 2 2020, 7:57 PM
kevans added inline comments.Jan 2 2020, 8:08 PM
sys/sys/_atomic64e.h
39 ↗(On Diff #66165)

Maybe rename this to HAS_EMULATED_ATOMIC64 or something like that since we'll use it for mips, too.

jeff accepted this revision.Jan 2 2020, 8:11 PM
jeff added inline comments.
sys/kern/subr_atomic64.c
57 ↗(On Diff #66165)

There is alright a macro for this. CACHE_LINE_SIZE

kevans added inline comments.Jan 2 2020, 8:19 PM
sys/sys/_atomic64e.h
44 ↗(On Diff #66165)

These declarations should also be included in the above _KERNEL check to hide them from userland

imp added inline comments.Jan 2 2020, 11:17 PM
sys/kern/subr_atomic64.c
57 ↗(On Diff #66165)

We need to make sure this can be option in kernel config file... unless CACHE LINE SIZE already does that...

Closed by commit rS356308: [PowerPC] [MIPS] Implement 32-bit kernel emulation of atomic64 operations (authored by bdragon). · Explain WhyJan 2 2020, 11:20 PM
This revision was automatically updated to reflect the committed changes.
bdragon added a commit: rS356308: [PowerPC] [MIPS] Implement 32-bit kernel emulation of atomic64 operations.
GitHub <noreply@github.com> added a commit: rG639dfeb83124: Update FreeBSD SPL atomics.Jun 8 2021, 2:46 PM
kp added a commit: rG92a6b17e8ba0: [PowerPC] [MIPS] Implement 32-bit kernel emulation of atomic64 operations.Oct 6 2021, 6:53 PM

Revision Contents
Changeset List

PathSize
head/
sys/
cddl/
compat/
opensolaris/
kern/
3 lines
sys/
6 lines
conf/
1 line
1 line
kern/
140 lines
mips/
include/
4 lines
powerpc/
include/
4 lines
sys/
80 lines

Diff 66279

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head/sys/cddl/compat/opensolaris/kern/opensolaris_atomic.c

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head/sys/cddl/compat/opensolaris/sys/atomic.h

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head/sys/conf/files.mips

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head/sys/conf/files.powerpc

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head/sys/kern/subr_atomic64.c

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head/sys/mips/include/atomic.h

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head/sys/powerpc/include/atomic.h

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head/sys/sys/_atomic64e.h

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