Re:There's No Such Thing as “Implicitly Atomic”
by _nalply on Thursday October 05, 2023 @03:17PM
(#37782978)
Or if I understood it correctly, there are platforms like CHERI which have metadata about memory, for example to detect invalid access. This metadata might race with the data itself.
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Re:There's No Such Thing as “Implicitly Atomic”
by jrtc27 on Friday October 06, 2023 @07:01PM
(#37797422)
The hardware must, and does, ensure that the metadata (both addressable - bounds, permissions, etc - and non-addressable - the tag) is kept atomic with the address portion of the capability, as otherwise you would be able to forge capabilities via such races. That is, you will never see a torn capability write, and the tag is updated atomically with every write, capability or not. This is easy to do since capabilities are always within a single cache line.