Re: [PATCHv2 RFC bpf-next 0/7] bpf: Add support for ftrace probe

On Thu, 15 Apr 2021 14:18:31 -0400
Steven Rostedt [off-list ref] wrote:

My last release of that code is here:

  https://lore.kernel.org/lkml/20190525031633.811342628@goodmis.org/ (local)

It allows you to "reserve data" to pass from the caller to the return, and
that could hold the arguments. See patch 15 of that series.

Note that implementation only lets you save up to 4 words on the stack, but
that can be changed. Or you could have a separate shadow stack for saving
arguments, and only pass the pointer to the location on the other stack
where those arguments are.

-- Steve