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Differential D36885

riscv: handle kernel PTE edge-case in pmap_enter_l2()
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Authored by mhorne on Oct 5 2022, 4:24 PM.
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markj
alc
Commits
rGce82d6846bda: riscv: handle kernel PTE edge-case in pmap_enter_l2()
rG1f9cc5ffc505: riscv: handle kernel PTE edge-case in pmap_enter_l2()
Summary

Page table pages are never freed from the kernel pmap, instead they are
zeroed when a range is unmapped. This allows future mappings to be
constructed more quickly. Detect this scenario in pmap_enter_l2(), so we
don't fail to create a superpage mapping when the 2MB range is actually
available.

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rG FreeBSD src repository
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Build Status
Buildable 47698
Build 44585: arc lint + arc unit

Event Timeline

mhorne created this revision.Oct 5 2022, 4:24 PM
Herald added a subscriber: imp. · View Herald TranscriptOct 5 2022, 4:24 PM
mhorne requested review of this revision.Oct 5 2022, 4:24 PM
Harbormaster completed remote builds in B47698: Diff 111467.Oct 5 2022, 4:24 PM
mhorne mentioned this in D36563: riscv: handle existing mapping in pmap_enter_l2().Oct 5 2022, 4:25 PM
markj accepted this revision.Oct 5 2022, 4:28 PM
This revision is now accepted and ready to land.Oct 5 2022, 4:28 PM
alc added inline comments.Oct 5 2022, 4:40 PM
sys/riscv/riscv/pmap.c
3206

On amd64 and arm64, we don't maintain an exact count of the valid mappings within a kernel page table page. If that is true on riscv, then this section of code should look more like the amd64 and arm64 versions.

mhorne marked an inline comment as done.Oct 5 2022, 4:58 PM
mhorne added inline comments.
sys/riscv/riscv/pmap.c
3206

Yes, good catch. I will make the adjustment as part of D36563.

Closed by commit rG1f9cc5ffc505: riscv: handle kernel PTE edge-case in pmap_enter_l2() (authored by mhorne). · Explain WhyOct 6 2022, 10:08 PM
This revision was automatically updated to reflect the committed changes.
mhorne marked an inline comment as done.
mhorne added a commit: rG1f9cc5ffc505: riscv: handle kernel PTE edge-case in pmap_enter_l2().
mhorne added a commit: rGce82d6846bda: riscv: handle kernel PTE edge-case in pmap_enter_l2().Oct 13 2022, 2:10 PM

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sys/
riscv/
riscv/
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Diff 111467

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sys/riscv/riscv/pmap.c

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