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

Details

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

Diff Detail

Repository
R10 FreeBSD src repository
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Event Timeline

mhorne requested review of this revision.Tue, Feb 9, 8:39 PM
sys/arm64/arm64/machdep.c
373

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.

Fix VM_MAXUSER_ADDRESS conditional. Round down address.

This revision is now accepted and ready to land.Fri, Feb 12, 3:25 PM
This revision was automatically updated to reflect the committed changes.