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Differential D45063

arm64: Reduce the kernel executable pages
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Authored by andrew on May 2 2024, 4:10 PM.
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manu
kib
markj
alc
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arm64
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rGe6928c33f60c: arm64: Reduce the kernel executable pages
Summary

When creating the kernel page tables we create them all executable to
allow the kernel to boot.

We can reduce the number of l2 blocks or l3 pages created as executable
by looking where the end of the .text section is and only marking
memory up to this as executable (rounded up to the block/page size).

Memory after the .text is marked as execute never as it will be data.

Sponsored by: Arm Ltd

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rG FreeBSD src repository
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Event Timeline

andrew created this revision.May 2 2024, 4:10 PM
Herald added a reviewer: manu. · View Herald TranscriptMay 2 2024, 4:10 PM
Herald added subscribers: emaste, imp. · View Herald Transcript
andrew requested review of this revision.May 2 2024, 4:10 PM
Harbormaster completed remote builds in B57545: Diff 138022.May 2 2024, 4:10 PM
andrew added a parent revision: D45062: arm64: Use tables to find early page tables.May 2 2024, 4:10 PM
andrew added a child revision: D45064: arm64: Create an L3 table to limit permissions.
emaste added a comment.May 6 2024, 3:46 PM

I assume that's supposed to be "l2 blocks" in the comment message?

emaste added a comment.May 6 2024, 3:51 PM

And I guess it's really marking memory beyond this (rounded up end of .text) as non-executable

andrew added reviewers: kib, markj, alc.Jun 6 2024, 2:44 PM
andrew updated this revision to Diff 156793.Tue, Jun 10, 5:01 PM

Rebase + move mov x10, x25 from D45062 to this patch

Harbormaster completed remote builds in B64750: Diff 156793.Tue, Jun 10, 5:01 PM
andrew edited the summary of this revision. (Show Details)Tue, Jun 10, 5:04 PM
alc accepted this revision.Wed, Jun 11, 7:31 PM
This revision is now accepted and ready to land.Wed, Jun 11, 7:31 PM
Closed by commit rGe6928c33f60c: arm64: Reduce the kernel executable pages (authored by andrew). · Explain WhyThu, Jun 12, 9:49 AM
This revision was automatically updated to reflect the committed changes.
andrew added a commit: rGe6928c33f60c: arm64: Reduce the kernel executable pages.

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sys/
arm64/
arm64/
19 lines

Diff 156872

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sys/arm64/arm64/locore.S

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