From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH bpf-next 2/3] bpf: emit RECORD_MMAP events for bpf prog load/unload Date: Thu, 20 Sep 2018 15:36:28 +0200 Message-ID: <20180920133628.GQ24142@hirez.programming.kicks-ass.net> References: <20180919223935.999270-1-ast@kernel.org> <20180919223935.999270-3-ast@kernel.org> <20180920084424.GN24124@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "David S . Miller" , daniel@iogearbox.net, acme@kernel.org, netdev@vger.kernel.org, kernel-team@fb.com To: Alexei Starovoitov Return-path: Received: from merlin.infradead.org ([205.233.59.134]:35612 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727078AbeITTUK (ORCPT ); Thu, 20 Sep 2018 15:20:10 -0400 Content-Disposition: inline In-Reply-To: <20180920084424.GN24124@hirez.programming.kicks-ass.net> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Sep 20, 2018 at 10:44:24AM +0200, Peter Zijlstra wrote: > On Wed, Sep 19, 2018 at 03:39:34PM -0700, Alexei Starovoitov wrote: > > void bpf_prog_kallsyms_del(struct bpf_prog *fp) > > { > > + unsigned long symbol_start, symbol_end; > > + /* mmap_record.filename cannot be NULL and has to be u64 aligned */ > > + char buf[sizeof(u64)] = {}; > > + > > if (!bpf_prog_kallsyms_candidate(fp)) > > return; > > > > spin_lock_bh(&bpf_lock); > > bpf_prog_ksym_node_del(fp->aux); > > spin_unlock_bh(&bpf_lock); > > + bpf_get_prog_addr_region(fp, &symbol_start, &symbol_end); > > + perf_event_mmap_bpf_prog(symbol_start, symbol_end - symbol_start, > > + buf, sizeof(buf)); > > } > > So perf doesn't normally issue unmap events.. We've talked about doing > that, but so far it's never really need needed I think. > > I feels a bit weird to start issuing unmap events for this. FWIW: https://lkml.kernel.org/r/20170127130702.GI6515@twins.programming.kicks-ass.net has talk of PERF_RECORD_MUNMAP