On Thu, Feb 15, 2024 at 11:27:22AM -0500, Steven Rostedt wrote: > On Wed, 14 Feb 2024 21:55:03 +0100 > Jiri Olsa <olsajiri@xxxxxxxxx> wrote: > > > > Masami, > > we recently discussed the possibility to store data between entry/return probe, > > IIUC your current patchset [0] allows that, but it seems to be shared across all > > the tracers for the given function (__ftrace_return_to_handler).. is the plan to > > make the shadow stack per tracer and function? /cc Steven > > The shadow stack is per task, but it saves unique data per tracer per function. > > It allows up to 16 different tracers attached to function graph tracing at > a time, as there is a limited shadow stack size, which all the attached > tracers use. Now you can create your own shadow stack per user (bpf > program?) and have a single registered function graph user that will demux > the data coming in and out of the function. ok, I guess that's fgraph_reserve_data/fgraph_retrieve_data api we'd like to share data between bpf programs executed from entry and exit handlers, that should do it thanks, jirka
