On Thu, Aug 29, 2024 at 10:03:04AM +1000, Alistair Francis wrote:
On Thu, Aug 29, 2024 at 9:45 AM Deepak Gupta <de...@rivosinc.com> wrote:
On Thu, Aug 29, 2024 at 09:29:49AM +1000, Alistair Francis wrote:
>On Thu, Aug 29, 2024 at 3:49 AM Deepak Gupta <de...@rivosinc.com> wrote:
>>
>> prot |= PAGE_WRITE;
>> }
>> - if (pte & PTE_X) {
>> + if (rwx & PTE_X) {
>> bool mxr = false;
>>
>> /*
>> @@ -1160,7 +1177,7 @@ restart:
>>
>> if (!((prot >> access_type) & 1)) {
>> /* Access check failed */
>> - return TRANSLATE_FAIL;
>> + return sstack_page ? TRANSLATE_PMP_FAIL : TRANSLATE_FAIL;
>
>Why is it a PMP error if it's a shadow stack page?
A shadow stack page is readable by regular loads.
We are making sure of that in `case PTE_W` in above switch case.
But shadow stack page is not writeable via regular stores. And must raise
access fault. return code `TRANSLATE_PMP_FAIL` is translated to access fault
while raising fault.
Ah, ok. It's worth commenting that we are returning TRANSLATE_PMP_FAIL
as that will be translated to an access fault
Ack.
Alistair
>
>Alistair
