Perform additional SP sanity check when unwinding stacks on ARMv[67]
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Authored by rwatson on Oct 4 2015, 10:49 AM.

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Reviewers

andrew
bz
br

Group Reviewers

ARM

Summary

Catch stack pointers that fall clearly outside of the kernel address space and abort kernel stack unwinding rather than continuing. For failed stack unwinding in the kernel debugger, keeling over just causes the debugger to re-enter. But for production uses of stack unwinding such as PMC and DTrace, a bad pointer dereference is less acceptable behaviour.

Test Plan

Deployed in Cambridge L41 2014-2015.

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Repository

rS FreeBSD src repository - subversion

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rwatson updated this revision to Diff 9123.Oct 4 2015, 10:49 AM

rwatson retitled this revision from to Perform additional SP sanity check when unwinding stacks on ARMv[67].

rwatson updated this object.

rwatson edited the test plan for this revision. (Show Details)

rwatson added reviewers: ARM, br, andrew, bz.

rwatson set the repository for this revision to rS FreeBSD src repository - subversion.

Herald added a subscriber: imp. · View Herald TranscriptOct 4 2015, 10:49 AM

andrew added inline comments.Oct 4 2015, 10:53 AM

sys/arm/arm/unwind.c
228	Why `0xffffff00`?

rwatson added inline comments.Oct 4 2015, 10:59 AM

sys/arm/arm/unwind.c
228	Hmm. Good question. I think that aspect of the change originated with you or br, but presumably reflects an actual case that arose. I can remove it, but perhaps br will remember and be able to comment?

mmel added a subscriber: mmel.Oct 4 2015, 1:08 PM

mmel added inline comments.

sys/arm/arm/unwind.c
228	You might use a similar approach what is used in https://reviews.freebsd.org/D3617. See read_instruction_nofault().

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sys/

arm/

unwind.c

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Diff 9123

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Perform additional SP sanity check when unwinding stacks on ARMv[67]Needs ReviewPublicActions