arm64: validate breakpoint registers
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Authored by mhorne on Feb 9 2021, 8:39 PM.

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Reviewers

markj
andrew
emaste
mgorny_gentoo.org
manu

Commits

rGde2b94228075: arm64: validate breakpoint registers

Summary

In particular, we want to disallow setting breakpoints on kernel
addresses from userspace. The control register fields are validated or
ignored as appropriate.

For reference: https://developer.arm.com/documentation/ddi0595/2020-12/AArch64-Registers/DBGBCR-n--EL1--Debug-Breakpoint-Control-Registers

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Repository

rG FreeBSD src repository

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Event Timeline

mhorne created this revision.Feb 9 2021, 8:39 PM

Herald added a reviewer: manu. · View Herald TranscriptFeb 9 2021, 8:39 PM

Herald added a subscriber: imp. · View Herald Transcript

mhorne requested review of this revision.Feb 9 2021, 8:39 PM

Harbormaster completed remote builds in B36839: Diff 83608.Feb 9 2021, 8:40 PM

mhorne mentioned this in D28415: arm64: extend struct db_reg to include watchpoint registers.Feb 9 2021, 8:48 PM

mhorne added a child revision: D28415: arm64: extend struct db_reg to include watchpoint registers.Feb 9 2021, 8:50 PM

markj added inline comments.Feb 9 2021, 9:03 PM

sys/arm64/arm64/machdep.c
374	I think this should be a >=. Contrary to the name, VM_MAXUSER_ADDRESS is not a valid user address. I guess it's ok to silently round down the address to the nearest half word boundary?
396–400	The `dbg_enable_count` value is left non-zero in error paths. I guess that's ok so long as we don't set DBGMON_ENABLED.