f00f: We don't need giant to manipulate vm structures
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Authored by imp on Sep 5 2021, 3:22 AM.

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kib
markj
jhb
mav

Commits

rG0cfc8b10edd7: f00f: We don't need giant to create IDT for workaround.

Summary

We don't need to assert we have Giant here. The VM subsystem
has been Giant free for some time now.

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Repository

rG FreeBSD src repository

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Tests Not Applicable

Event Timeline

imp requested review of this revision.Sep 5 2021, 3:22 AM

imp created this revision.

Harbormaster completed remote builds in B41382: Diff 94677.Sep 5 2021, 3:22 AM

imp added reviewers: kib, markj, mav, jhb.Sep 5 2021, 3:24 AM

This does not have anything to do with VM.

This revision is now accepted and ready to land.Sep 5 2021, 3:41 AM

markj accepted this revision.Sep 5 2021, 5:15 PM

mav resigned from this revision.Sep 5 2021, 9:23 PM

In D31839#718224, @kib wrote:

This does not have anything to do with VM.

What's the right low level term for the pmap and IDT fiddling it does then?

In D31839#718395, @imp wrote:

In D31839#718224, @kib wrote:

This does not have anything to do with VM.

What's the right low level term for the pmap and IDT fiddling it does then?

It is part of the cpu setup code. Actually it is safe to do this manipulation there because

all machines where it matters are UP
interrupts are disabled

These are the guarantees that this code needs to work.

pmap_trm_alloc() allocates memory in the trampoline area which is shared between kernel and userspace. After 4/4 UVA/KVA split was implemented, kernel no longer shares (whole) address space with userspace on i386.

Closed by commit rG0cfc8b10edd7: f00f: We don't need giant to create IDT for workaround. (authored by imp). · Explain WhySep 29 2021, 4:45 PM

This revision was automatically updated to reflect the committed changes.

imp added a commit: rG0cfc8b10edd7: f00f: We don't need giant to create IDT for workaround..