On Fri, Oct 25, 2019 at 4:03 AM Mark Rutland <mark.rutland@xxxxxxx> wrote: > I'm guessing it's difficult to always figure out the SCS slot for an > instrumented callsite unless we pass this explicitly from the ftrace > entry code, so we'd probably have to change some common infrastructure > for that. > > We have a similar issue with pointer authentication, and we're solving > that with -fpatchable-function-entry, which allows us to hook the > callsite before it does anything with the return address. IIUC we could > use the same mechanism here (and avoid introducing a third). > > Are there plans to implement -fpatchable-function-entry on the clang > side? I'm not sure if there are plans at the moment, but if this feature is needed for PAC, adding it to clang shouldn't be a problem. Nick, did you have any thoughts on this? Sami
