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Peter Anvin" , x86@kernel.org, Mark Rutland , Alexander Shishkin , Mathieu Poirier , Leo Yan , Jiri Olsa , linux-kernel@vger.kernel.org Subject: Re: [PATCH V6 08/15] ftrace: Add perf text poke events for ftrace trampolines Message-ID: <20200427201043.GP19437@kernel.org> References: <20200405201327.7332-1-adrian.hunter@intel.com> <20200405201327.7332-9-adrian.hunter@intel.com> <20200421134504.GQ20730@hirez.programming.kicks-ass.net> <20200422114659.GE20730@hirez.programming.kicks-ass.net> <76de871f-fb0a-6918-68a9-94aa7b049d6b@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <76de871f-fb0a-6918-68a9-94aa7b049d6b@intel.com> X-Url: http://acmel.wordpress.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Mon, Apr 27, 2020 at 10:23:05AM +0300, Adrian Hunter escreveu: > On 22/04/20 2:46 pm, Peter Zijlstra wrote: > > On Wed, Apr 22, 2020 at 10:39:06AM +0300, Adrian Hunter wrote: > >> On 21/04/20 4:45 pm, Peter Zijlstra wrote: > >>> 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. > >> > >> How about adding this: > >> > >> There can be 3 text_poke events for ftrace trampolines: > >> > >> 1. NULL -> trampoline > >> By ftrace_update_trampoline() when !ops->trampoline > >> Trampoline created > >> > >> 2. [e.g. on x86] CALL rel32 -> CALL rel32 > >> By arch_ftrace_update_trampoline() when ops->trampoline and > >> ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP > >> [e.g. on x86] via text_poke_bp() which generates text poke events > >> Trampoline-called function target updated > >> > >> 3. trampoline -> NULL > >> By ftrace_trampoline_free() when ops->trampoline and > >> ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP > >> Trampoline freed > > > > Yes, very nice. Thanks! > > Arnaldo, do you have this patchset on your radar? Now it is, will look it into it, - Arnaldo