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Peter Anvin" , x86@kernel.org, Mark Rutland , Alexander Shishkin , Mathieu Poirier , Leo Yan , Arnaldo Carvalho de Melo , Jiri Olsa , linux-kernel@vger.kernel.org Subject: Re: [PATCH V6 08/15] ftrace: Add perf text poke events for ftrace trampolines Message-ID: <20200421134504.GQ20730@hirez.programming.kicks-ass.net> References: <20200405201327.7332-1-adrian.hunter@intel.com> <20200405201327.7332-9-adrian.hunter@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200405201327.7332-9-adrian.hunter@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 05, 2020 at 11:13:20PM +0300, Adrian Hunter wrote: > Add perf text poke events for ftrace trampolines when created and when > freed. Maybe also put in a little more detail on the various events. Because arch_ftrace_update_trampoline() can also generate text_poke_bp() events, to update an existing trampoline. A diagram, like with the kprobes thing perhaps. > Signed-off-by: Adrian Hunter > --- > kernel/trace/ftrace.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 398d58b8ffa5..3318f7eca76c 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -2792,6 +2792,13 @@ static void ftrace_trampoline_free(struct ftrace_ops *ops) > { > if (ops && (ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP) && > ops->trampoline) { > + /* > + * Record the text poke event before the ksymbol unregister > + * event. > + */ > + perf_event_text_poke((void *)ops->trampoline, > + (void *)ops->trampoline, > + ops->trampoline_size, NULL, 0); > perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, > ops->trampoline, ops->trampoline_size, > true, FTRACE_TRAMPOLINE_SYM); > @@ -6816,6 +6823,13 @@ static void ftrace_update_trampoline(struct ftrace_ops *ops) > perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, > ops->trampoline, ops->trampoline_size, false, > FTRACE_TRAMPOLINE_SYM); > + /* > + * Record the perf text poke event after the ksymbol register > + * event. > + */ > + perf_event_text_poke((void *)ops->trampoline, NULL, 0, > + (void *)ops->trampoline, > + ops->trampoline_size); > } > } > > -- > 2.17.1 >