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Differential D3796

Modules support for arm64
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Authored by kib on Oct 4 2015, 11:33 AM.
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Reviewers
emaste
andrew
Commits
rS289039: Build changes that allow the modules on arm64.
rS289037: Disable syscons and vpo modules for arm64.
rS289036: Add the arm64 define.
rS289035: Implement in-kernel relocator for the arm64 module linker.
Summary

I have to use shared objects format for modules, instead of relocatable objects, due to limitations in the addressing.

The bug in 2.25.1 binutils requires the hack to avoid ld -r, which eg makes ctfmerge non-functional. I verified that git head for binutils has the issue fixed, but I did not digged exact change that did it.

It seems that the architecture requires -fPIC for shared objects, linker was not able to link modules built without -fPIC.

Diff Detail

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rS FreeBSD src repository - subversion
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Event Timeline

kib updated this revision to Diff 9126.Oct 4 2015, 11:33 AM
kib retitled this revision from to Modules support for arm64.
kib updated this object.
kib edited the test plan for this revision. (Show Details)
kib added reviewers: andrew, emaste.
kib set the repository for this revision to rS FreeBSD src repository - subversion.
kib added a project: arm64.
Herald added a subscriber: imp. · View Herald TranscriptOct 4 2015, 11:33 AM
andrew added inline comments.Oct 4 2015, 12:19 PM
sys/arm64/arm64/elf_machdep.c
191–192 ↗(On Diff #9126)

Used

208 ↗(On Diff #9126)

Used

sys/arm64/arm64/trap.c
278 ↗(On Diff #9126)

This appears to be unrelated (but useful, just commit)

sys/dev/sym/sym_hipd.c
140 ↗(On Diff #9126)

Could this be a dmb(ish)?

kib marked 3 inline comments as done.Oct 4 2015, 12:58 PM
kib added inline comments.
sys/dev/sym/sym_hipd.c
140 ↗(On Diff #9126)

I think this driver should be disabled for anything but i386. I have no opinion about ish/sy, in fact, I think that either one is wrong.

kib updated this revision to Diff 9130.Oct 4 2015, 1:08 PM
kib removed rS FreeBSD src repository - subversion as the repository for this revision.

Remove __unused; some editing to the ld comment. Committed the trap.c assert change.

kib updated this revision to Diff 9131.Oct 4 2015, 3:48 PM
kib set the repository for this revision to rS FreeBSD src repository - subversion.

Full context, by emaste request.

kib added a comment.Oct 5 2015, 4:44 AM

BTW, after the agreement to use shared objects as the module format is reached, it may be easier to expedite this in two stages. First, elf_machdep.c changes are really straightforward. Then, the sys/conf changes (or hacks, if you so inclined) can be shaped.

emaste added inline comments.Oct 5 2015, 6:59 AM
sys/arm64/arm64/elf_machdep.c
161 ↗(On Diff #9131)

ugh, seems we do this on other archs too. should just return -1 instead?

sys/conf/kern.post.mk
215 ↗(On Diff #9131)

Sigh, I wish we didn't need this. But I don't think there's a better way.

sys/conf/kmod.mk
132–135 ↗(On Diff #9131)

I think we ought to keep these md parts in (mostly) alpha order

192 ↗(On Diff #9131)

We ought to see if this fix made it back to the 2.25 branch and try to get it merged back if not so that we can pick it up with the next binutils port update.

sys/dev/sym/sym_hipd.c
140 ↗(On Diff #9131)

Agreed, this has no value on arm64.

sys/modules/Makefile
483 ↗(On Diff #9131)

this one could stay in alpha order

emaste edited edge metadata.Oct 5 2015, 7:07 AM

BTW, after the agreement to use shared objects as the module format is reached, it may be easier to expedite this in two stages. First, elf_machdep.c changes are really straightforward. Then, the sys/conf changes (or hacks, if you so inclined) can be shaped.

Sounds good to me.

kib marked 2 inline comments as done.Oct 5 2015, 7:19 AM
kib added inline comments.
sys/arm64/arm64/elf_machdep.c
161 ↗(On Diff #9131)

The presence of unknown relocation type practically means that the loaded file is corrupted. There are very high chances that we already applied some relocations, and that relocations can modify arbitrary kernel memory.

Since we detected a blob, which is not of the expected content, and which already polluted kernel address space, I think that the panic is the best reaction.

sys/conf/kern.post.mk
215 ↗(On Diff #9131)

This is a consequence of calling the $MACHINE arm64 instead of aarch64. It was a reasonable thing to distinguish between powerpc and powerpc64, but it is not clear that having three names aarch64/armv8/arm64, all of them ortohonal, would serve us usefully in future.

sys/conf/kmod.mk
192 ↗(On Diff #9131)

Wouldn't it is wiser to wait for 2.26 and then remove the hack ?

kib updated this revision to Diff 9154.Oct 5 2015, 7:21 AM
kib edited edge metadata.

Reorder some Makefile hacks.

Also, I added ff copyright for year 2015. Please review the existing copyright holders in the elf_machdep.c. I believe that only Andrew and FF are correct, everything else is copy/paste mistake.

emaste added inline comments.Oct 5 2015, 7:24 AM
sys/conf/kmod.mk
192 ↗(On Diff #9131)

As long as it's going to be arriving in time that makes sense.

emaste added a comment.Oct 6 2015, 6:54 PM
In D3796#78662, @kib wrote:

Reorder some Makefile hacks.

Also, I added ff copyright for year 2015. Please review the existing copyright holders in the elf_machdep.c. I believe that only Andrew and FF are correct, everything else is copy/paste mistake.

Yes, it looks like you are correct, this is new work.

andrew accepted this revision.Oct 8 2015, 12:32 PM
andrew edited edge metadata.

I've tested on a HiKey board by both loading modules from loader, and with kldload.

sys/arm64/arm64/elf_machdep.c
213 ↗(On Diff #9154)

Why is this needed?

This revision is now accepted and ready to land.Oct 8 2015, 12:32 PM
emaste accepted this revision.Oct 8 2015, 1:28 PM
emaste edited edge metadata.
Closed by commit rS289035: Implement in-kernel relocator for the arm64 module linker. (authored by kib). · Explain WhyOct 8 2015, 4:58 PM
This revision was automatically updated to reflect the committed changes.
kib reopened this revision.Oct 8 2015, 5:02 PM

Partial commit was done; more to come.

This revision is now accepted and ready to land.Oct 8 2015, 5:02 PM
Closed by commit rS289036: Add the arm64 define. (authored by kib). · Explain WhyOct 8 2015, 5:32 PM
This revision was automatically updated to reflect the committed changes.

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head/sys/dev/sym/sym_hipd.c

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