On Wed, Feb 21, 2024 at 04:47:11PM -0800, Deepak Gupta wrote:
On Tue, Feb 06, 2024 at 04:01:28PM +0000, Mark Brown wrote:
+#define SHADOW_STACK_SET_TOKEN (1ULL << 0) /* Set up a restore token in the shadow stack */
For arm64 I also added a SHADOW_STACK_SET_MARKER for adding a top of stack marker, did you have any thoughts on that for RISC-V? I think x86 were considering adding it too, it'd be good if we could get things consistent.
Please correct me on this. A token at the top which can't be consumed to restore but *just* purely as marker, right?
Yes, for arm64 we just leave a zero word (which can't be a valid token) above the stack switch token, that does mean you can't exactly tell that the top of stack marker is there unless there's also a stack switch token below it.
It's a good design basic with not a lot of cost.
I think risc-v should be able to converge on that.
Great.