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Differential D54920

STACKALIGN: Reimplement in terms of __align_down
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Authored by jhb on Tue, Jan 27, 10:29 PM.
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emaste
imp
jrtc27
riscv

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brooks
kib
andrew
manu
Commits
rGe9a697bf20cc: STACKALIGN: Reimplement in terms of __align_down
Summary

This changes STACKALIGN to be type-preserving when operating on
pointers.

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rG FreeBSD src repository
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Event Timeline

jhb created this revision.Tue, Jan 27, 10:29 PM
Herald added a reviewer: andrew. · View Herald TranscriptTue, Jan 27, 10:29 PM
Herald added a reviewer: andrew. · View Herald Transcript
Herald added a reviewer: manu. · View Herald Transcript
Herald added subscribers: riscv, emaste, imp. · View Herald Transcript
jhb requested review of this revision.Tue, Jan 27, 10:29 PM
Harbormaster completed remote builds in B70173: Diff 170616.Tue, Jan 27, 10:29 PM
kib added inline comments.Tue, Jan 27, 10:44 PM
sys/arm/include/param.h
49–50

Why STACKALIGN needs to be MD then? It is enough to have STACKALIGNBYTES defined in machine/param.h.
And please add a comment that it is type-preserving.

jrtc27 added a subscriber: jrtc27.Wed, Jan 28, 1:54 AM

Effort: CHERI upstreaming or whatever it is seems like it would apply?

brooks accepted this revision.Wed, Jan 28, 10:12 AM
brooks added inline comments.
sys/arm/include/param.h
49–50

It's only defined on arm/riscv.

STACKALIGNBYTES should surely be STACKALIGN_MASK or the like, but that's a different change.

This revision is now accepted and ready to land.Wed, Jan 28, 10:12 AM
kib added inline comments.Wed, Jan 28, 10:16 AM
sys/arm/include/param.h
49–50

It's only defined on arm/riscv.

Yes, this is why I said that it is enough to have STACKALIGNBYTES in machine/param.h.
sys/param.h could then do

#ifdef STACKALIGNBYTES
#define STACKALIGN ...
#endif

and it would be immediately have uses at least on amd64 where we align stack after the signal frame.
Might be for i386 too, but I do not remember.

jhb added inline comments.Wed, Jan 28, 11:52 PM
sys/arm/include/param.h
49–50

I would be happy to move it. I do think it would be nicer on other arches as well. I do wish the STACKALIGNBYTES wasn't the biased value. I'm not sure if we expose this to userland though. :( Let me see if it's feasible to change that to the unbiased value.

jhb updated this revision to Diff 171274.Thu, Feb 5, 6:38 PM

Centralize STACKALIGN and pass tinderbox

This revision now requires review to proceed.Thu, Feb 5, 6:38 PM
Harbormaster completed remote builds in B70443: Diff 171274.Thu, Feb 5, 6:39 PM
kib accepted this revision.Thu, Feb 5, 6:42 PM

There are opportunities with amd64 at least, but I can do it myself after this patch lands. Thanks.

This revision is now accepted and ready to land.Thu, Feb 5, 6:42 PM
brooks accepted this revision.Fri, Feb 6, 9:13 AM
Closed by commit rGe9a697bf20cc: STACKALIGN: Reimplement in terms of __align_down (authored by jhb). · Explain WhyFri, Feb 6, 3:31 PM
This revision was automatically updated to reflect the committed changes.
jhb added a commit: rGe9a697bf20cc: STACKALIGN: Reimplement in terms of __align_down.

Revision Contents
Changeset List

PathSize
lib/
libc/
aarch64/
gen/
3 lines
riscv/
gen/
3 lines
sys/
arm/
arm/
2 lines
2 lines
4 lines
include/
1 line
arm64/
arm64/
2 lines
2 lines
include/
1 line
linux/
2 lines
riscv/
include/
1 line
riscv/
2 lines
sys/
3 lines

Diff 171338

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lib/libc/aarch64/gen/makecontext.c

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lib/libc/riscv/gen/makecontext.c

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sys/arm/arm/exec_machdep.c

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sys/arm/arm/machdep.c

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sys/arm/arm/vm_machdep.c

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sys/arm/include/param.h

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sys/arm64/arm64/exec_machdep.c

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sys/arm64/arm64/vm_machdep.c

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sys/arm64/include/param.h

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sys/arm64/linux/linux_sysvec.c

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sys/riscv/include/param.h

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sys/riscv/riscv/exec_machdep.c

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sys/sys/param.h

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