Move instructions into the arm64 exception vectors
ClosedPublic
Actions

Authored by andrew on Jan 5 2022, 3:14 PM.

Details

Reviewers

kib
markj
manu

Group Reviewers

arm64

Commits

rG3822a970ff3c: Move instructions into the arm64 exception vectors
rG77402d2834e6: Move instructions into the arm64 exception vectors

Summary

We have 32 instructions in each exception vector on arm64. Previously
only one was used to branch to the handler function. We can split the
start of these functions and move some of the instructions into the
vectors.

Diff Detail

Repository

rG FreeBSD src repository

Lint

Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

andrew created this revision.Jan 5 2022, 3:14 PM

Herald added a reviewer: manu. · View Herald TranscriptJan 5 2022, 3:14 PM

Herald added subscribers: emaste, imp. · View Herald Transcript

andrew requested review of this revision.Jan 5 2022, 3:14 PM

Harbormaster completed remote builds in B43717: Diff 100976.Jan 5 2022, 3:14 PM

What's the advantage of setting up the handlers this way?

sys/arm64/arm64/exception.S
39
274	Why is it not `vempty 0`?

Fix vempty exception level values

Harbormaster completed remote builds in B43718: Diff 100977.Jan 5 2022, 3:27 PM

In D33751#763217, @markj wrote:

What's the advantage of setting up the handlers this way?

I expect any reasonable implementation to prefetch the whole cache line from the exception vector, on exception. Using a single instruction there wastes cache.

This revision is now accepted and ready to land.Jan 6 2022, 12:53 AM

markj accepted this revision.Jan 6 2022, 2:39 PM

Closed by commit rG77402d2834e6: Move instructions into the arm64 exception vectors (authored by andrew). · Explain WhyJan 10 2022, 12:02 PM

This revision was automatically updated to reflect the committed changes.

andrew added a commit: rG77402d2834e6: Move instructions into the arm64 exception vectors.

andrew added a commit: rG3822a970ff3c: Move instructions into the arm64 exception vectors.Jan 31 2022, 11:34 AM