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Differential D54839

powerpc: Fix alignment of initial PCB on kstack
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Authored by jhb on Fri, Jan 23, 6:45 PM.
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jhibbits
adrian
fuz
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cheri
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rG9272b7806266: powerpc: Fix alignment of initial PCB on kstack
Summary

Commit cc81c44dd806737f98b4fd4094674dd71c8749f3 aimed to consolidate
duplicated code between the Book-E and AIM backends. For
cpu_thread_alloc cpu_thread_alloc and cpu_fork it used the AIM
functions which used a bogus alignment mask (~0x2f). The Book-E
functions used a proper alignment mask (~0x3f). The AIM functions
appear to have been busted since they were first imported in commit
919cb3362fded33aca682a6ac57777f8fff86e36.

To fix, use the Book-E mask which requests 64 byte alignment.
Probably this was harmless in practice since td_kstack is page aligned
and struct pcb is probably a multiple of 32 bytes in size, so the 0x10
bit should have been clear anyway.

Fixes: cc81c44dd806 ("Unify ABI-related bits of the Book-E and AIM...")
Effort: CHERI upstreaming
Sponsored by: AFRL, DARPA

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Repository
rG FreeBSD src repository
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Build Status
Buildable 70077
Build 66960: arc lint + arc unit

Event Timeline

jhb created this revision.Fri, Jan 23, 6:45 PM
Herald added a subscriber: imp. · View Herald TranscriptFri, Jan 23, 6:45 PM
jhb requested review of this revision.Fri, Jan 23, 6:45 PM
Herald added a reviewer: cheri. · View Herald TranscriptFri, Jan 23, 6:45 PM
Harbormaster completed remote builds in B70077: Diff 170282.Fri, Jan 23, 6:45 PM
jhb added a child revision: D54840: sys: Use __is_aligned and __align_down for some kstack alignment operations.Fri, Jan 23, 6:45 PM
jhibbits accepted this revision.Fri, Jan 23, 7:09 PM

If that's used any more often than these two locations, we may want to add a STACK_ALIGNMENT macro.

This revision is now accepted and ready to land.Fri, Jan 23, 7:09 PM
fuz accepted this revision.Fri, Jan 23, 7:51 PM

Looks reasonable.

jhb added a comment.Sun, Jan 25, 4:56 AM

These are the only two I found. Some other architectures have a STACKALIGN macro

Closed by commit rG9272b7806266: powerpc: Fix alignment of initial PCB on kstack (authored by jhb). · Explain WhyTue, Jan 27, 6:32 PM
This revision was automatically updated to reflect the committed changes.
jhb added a commit: rG9272b7806266: powerpc: Fix alignment of initial PCB on kstack.

Revision Contents
Changeset List

PathSize
sys/
powerpc/
powerpc/
2 lines
2 lines

Diff 170282

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sys/powerpc/powerpc/exec_machdep.c

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sys/powerpc/powerpc/vm_machdep.c

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