Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Zcherilevels RV32 stripping EL clarification #428

Closed
jamie-melling opened this issue Oct 21, 2024 · 2 comments · Fixed by #427
Closed

Zcherilevels RV32 stripping EL clarification #428

jamie-melling opened this issue Oct 21, 2024 · 2 comments · Fixed by #427
Assignees
@arichardson

Comments

@jamie-melling
Copy link

If you have a quadrant 1 capability with perms[2:0] equal to either 0-1 or 4-5 (with w-perm) and remove just EL, there are two possible outcomes, neither of which break monotonicity. Either you stay in quadrant 1 and strip C and LM to get an R, W and X capability. The other option is to create a quadrant 2 capability where you strip LM, W and X to get an R and C capability. The rules laid out in ACPERM do not cover which mutation is desired.

One other note, small spec bug in ACPERM rules.
image
@tariqkurd-repo
Copy link
Collaborator

tariqkurd-repo commented Oct 21, 2024 •
edited
Loading

It looks like these rules need a thorough review.
In #421 we default to RC permission where there is a choice, so maybe we should do the same here.

@tomaird
Copy link
Contributor

tomaird commented Oct 22, 2024

Typo fix here: #429

@tariqkurd-repo tariqkurd-repo mentioned this issue Oct 30, 2024
Merged
@tariqkurd-repo tariqkurd-repo mentioned this issue Nov 5, 2024
Merged
tariqkurd-repo added a commit that referenced this issue Nov 6, 2024
@tariqkurd-repo
Fix RV32 Zcherilevels ACPERM (#440)
b7c9d7e 
This version has been verified by a python script which checks all
possible combinations of removing permissions from maximum permissions

additional fix for #428
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees

@arichardson arichardson

Labels
None yet
Projects
None yet
Milestone
No milestone
Development

Successfully merging a pull request may close this issue.

apply ACPERM rules in order tariqkurd-repo/riscv-cheri
4 participants
@arichardson @tomaird @tariqkurd-repo @jamie-melling