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Differential D56306

arm64: Add a cmap page to pmap
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Authored by andrew on Wed, Apr 8, 12:59 PM.
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Reviewers
alc
kib
markj
manu
Group Reviewers
arm64
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rGc208439cdb58: arm64: Add a cmap page to pmap
Summary

When modifying mappings in pmap we may need to perform a
break-before-make sequence. This creates an invalid mapping, then
recreates it with the changes.

When modifying DMAP mappings we may be changing the mapping that
contains its own page table then after breaking the old entry we are
unable to create the new entry.

To fix this create a map that can be used & won't be affected by the
break-before-make sequence.

Sponsored by: Arm Ltd

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rG FreeBSD src repository
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Event Timeline

andrew created this revision.Wed, Apr 8, 12:59 PM
Herald added a reviewer: manu. · View Herald TranscriptWed, Apr 8, 12:59 PM
Herald added subscribers: emaste, imp. · View Herald Transcript
andrew requested review of this revision.Wed, Apr 8, 12:59 PM
Harbormaster completed remote builds in B72050: Diff 175102.Wed, Apr 8, 12:59 PM
andrew mentioned this in D55943: arm64: Handle changing self-referential DMAP pages.Wed, Apr 8, 1:03 PM
andrew added a child revision: D55943: arm64: Handle changing self-referential DMAP pages.Wed, Apr 8, 1:04 PM
kib accepted this revision.Wed, Apr 8, 4:39 PM
This revision is now accepted and ready to land.Wed, Apr 8, 4:39 PM
kib added a comment.Wed, Apr 8, 4:42 PM

I only have one question, why this cmap needs to be per-cpu? I do not think that it is high-contention resource.

markj added inline comments.Fri, Apr 10, 11:29 AM
sys/arm64/arm64/pmap.c
1427

Isn't this the same as VIRTUAL_MAX_KERNEL_ADDRESS - PMAP_MAPDEV_EARLY_SIZE, which we already bootstrapped above?

1442

Extra newline.

1469
andrew updated this revision to Diff 175226.Fri, Apr 10, 2:10 PM

Remove per-cpu pointers

This revision now requires review to proceed.Fri, Apr 10, 2:10 PM
Harbormaster completed remote builds in B72105: Diff 175226.Fri, Apr 10, 2:10 PM
andrew edited the summary of this revision. (Show Details)Fri, Apr 10, 2:11 PM
kib accepted this revision.Fri, Apr 10, 2:32 PM
This revision is now accepted and ready to land.Fri, Apr 10, 2:32 PM
Closed by commit rGc208439cdb58: arm64: Add a cmap page to pmap (authored by andrew). · Explain WhyMon, Apr 13, 2:24 PM
This revision was automatically updated to reflect the committed changes.
andrew added a commit: rGc208439cdb58: arm64: Add a cmap page to pmap.

Revision Contents
Changeset List

PathSize
sys/
arm64/
arm64/
19 lines

Diff 175430

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sys/arm64/arm64/pmap.c

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