2019年5月7日(火) 21:54 Steven Rostedt <rostedt@xxxxxxxxxxx>: > > On Tue, 7 May 2019 14:41:31 +0200 > Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > > Kprobes sets the FTRACE_OPS_FL_IPMODIFY flag, thus > > > they can never be put at the same location that is being live patched. > > > > OK, so do we want to allow kprobes that also modify regs->sp ? Because > > then we need to change these trampolines a bit. > > > > I'd prefer not to allow kprobes this. > > I believe no kprobe changes sp, because it would have had the same > issues we are trying to solve now. And even though we are changing > things to allow it, it's not a regression to keep kprobes from doing it. No, kprobes doesn't allow to change sp. At this moment we can't change "®s->sp" since it is just a value :) kprobes user (e.g. function fault-injection) will change regs->ip, that is why kprobes sets IPMODIFY flag. Thank you, -- Masami Hiramatsu mailto:masami.hiramatsu@xxxxxxxxx
