Hi Dave,
On 9/16/2021 8:30 AM, Dave Hansen wrote:
On 9/15/21 1:31 PM, Reinette Chatre wrote:
Add a test to ensure that (1) PTE permissions can be changed as long as
they do not exceed EPCM permissions, and (2) even if EPCM permissions
allow a page to be written to, if the PTE permissions do not then a #PF
should be generated when attempting to write to a (from PTE perspective)
read-only page.
It took me a minute to figure out what this was trying to say.
The goal was to describe what features/functionalities are being tested.
You accurately point out that it is not clear how the test implemented
in the patch matches with these test goals.
Maybe
breaking it down into these three steps would help:
Add a test that:
(1) Creates an SGX enclave page with writable EPCM permission
(2) Changes the PTE permission on the page to read-only. This should
be permitted because the permission does not exceed the EPCM
permission.
(3) Attempts a write to the page and generate a page fault (#PF)
because of the read-only PTE.
Thank you for the suggestion. What I understand from your feedback is
that I should mix the description of the actual test with what
features/functionalities are being tested. You do so in your suggestion
for (2) and to do the same for (3) I now plan to expand it to:
(3) Attempts a write to the page. This should generate a page fault
(#PF) because of the read-only PTE even though the EPCM
permissions allow the page to be written to.
Reinette
