On Fri, Jan 04, 2019 at 05:50:18PM +0000, Mark Rutland wrote: > Hi Torsten, > > On Fri, Jan 04, 2019 at 03:10:53PM +0100, Torsten Duwe wrote: > > Use -fpatchable-function-entry (gcc8) to add 2 NOPs at the beginning > > of each function. Replace the first NOP thus generated with a quick LR > > saver (move it to scratch reg x9), so the 2nd replacement insn, the call > > to ftrace, does not clobber the value. Ftrace will then generate the > > standard stack frames. > > Do we know what the overhead would be, if this was a link time change for the first instruction? Also, I was under the impression that some arch's do ftrace_call_replace under stop_machine(), is that a possibility here? Balbir Singh
