From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8A24C433E7 for ; Mon, 19 Oct 2020 20:53:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8DBE22222C for ; Mon, 19 Oct 2020 20:53:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NvOkSLSa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728974AbgJSUxx (ORCPT ); Mon, 19 Oct 2020 16:53:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:39797 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728801AbgJSUxw (ORCPT ); Mon, 19 Oct 2020 16:53:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603140831; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ljaLzhezy+nq1DMv1yiAIWoIK2NJ/V3HeecNHEJEUIQ=; b=NvOkSLSawWtA0sCJCJgVr8HrNs7cQgEhbLZK05Al1dzb8nRyCUaQE1r+Aw0ILgvbalQ4oh he2FTPFa2ZRi6Svshp7kv0FXAV9chUcDWec/X3GaL5t9DHYFVnbWvVts+KqwP7z5MgxltO McbMzK4fN7NDUQq24ecG77kCxo6vAVU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-539-qQmKvwokOQOgVfBTKE37eQ-1; Mon, 19 Oct 2020 16:53:47 -0400 X-MC-Unique: qQmKvwokOQOgVfBTKE37eQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C2DAD1015CA2; Mon, 19 Oct 2020 20:53:45 +0000 (UTC) Received: from krava (unknown [10.40.194.190]) by smtp.corp.redhat.com (Postfix) with SMTP id EECC727CCA; Mon, 19 Oct 2020 20:53:43 +0000 (UTC) Date: Mon, 19 Oct 2020 22:53:43 +0200 From: Jiri Olsa To: Tommi Rantala Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Namhyung Kim Subject: Re: [PATCH] perf tools: Fix crash with non-jited bpf progs Message-ID: <20201019205343.GA2064287@krava> References: <20201016114718.54332-1-tommi.t.rantala@nokia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201016114718.54332-1-tommi.t.rantala@nokia.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 16, 2020 at 02:47:18PM +0300, Tommi Rantala wrote: > The addr in PERF_RECORD_KSYMBOL events for non-jited bpf progs points to > the bpf interpreter, ie. within kernel text section. When processing the > unregister event, this causes unexpected removal of vmlinux_map, > crashing perf later in cleanup: > > # perf record -- timeout --signal=INT 2s /usr/share/bcc/tools/execsnoop > PCOMM PID PPID RET ARGS > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.208 MB perf.data (5155 samples) ] > perf: tools/include/linux/refcount.h:131: refcount_sub_and_test: Assertion `!(new > val)' failed. > Aborted (core dumped) > > # perf script -D|grep KSYM > 0 0xa40 [0x48]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b530 len 0 type 1 flags 0x0 name bpf_prog_f958f6eb72ef5af6 > 0 0xab0 [0x48]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b530 len 0 type 1 flags 0x0 name bpf_prog_8c42dee26e8cd4c2 > 0 0xb20 [0x48]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b530 len 0 type 1 flags 0x0 name bpf_prog_f958f6eb72ef5af6 > 108563691893 0x33d98 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3b0 len 0 type 1 flags 0x0 name bpf_prog_bc5697a410556fc2_syscall__execve > 108568518458 0x34098 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3f0 len 0 type 1 flags 0x0 name bpf_prog_45e2203c2928704d_do_ret_sys_execve > 109301967895 0x34830 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3b0 len 0 type 1 flags 0x1 name bpf_prog_bc5697a410556fc2_syscall__execve > 109302007356 0x348b0 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3f0 len 0 type 1 flags 0x1 name bpf_prog_45e2203c2928704d_do_ret_sys_execve > perf: tools/include/linux/refcount.h:131: refcount_sub_and_test: Assertion `!(new > val)' failed. > > Here the addresses match the bpf interpreter: > > # grep -e ffffffffa9b6b530 -e ffffffffa9b6b3b0 -e ffffffffa9b6b3f0 /proc/kallsyms > ffffffffa9b6b3b0 t __bpf_prog_run224 > ffffffffa9b6b3f0 t __bpf_prog_run192 > ffffffffa9b6b530 t __bpf_prog_run32 > > Fix by not allowing vmlinux_map to be removed by PERF_RECORD_KSYMBOL > unregister event. > > Signed-off-by: Tommi Rantala nice, I almost forgot about non jit mode by now ;-) Acked/Tested-by: Jiri Olsa thanks, jirka > --- > tools/perf/util/machine.c | 11 ++++++++++- > tools/perf/util/symbol.c | 7 +++++++ > tools/perf/util/symbol.h | 2 ++ > 3 files changed, 19 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c > index 85587de027a5..d93d35463c61 100644 > --- a/tools/perf/util/machine.c > +++ b/tools/perf/util/machine.c > @@ -786,11 +786,20 @@ static int machine__process_ksymbol_unregister(struct machine *machine, > union perf_event *event, > struct perf_sample *sample __maybe_unused) > { > + struct symbol *sym; > struct map *map; > > map = maps__find(&machine->kmaps, event->ksymbol.addr); > - if (map) > + if (!map) > + return 0; > + > + if (map != machine->vmlinux_map) > maps__remove(&machine->kmaps, map); > + else { > + sym = dso__find_symbol(map->dso, map->map_ip(map, map->start)); > + if (sym) > + dso__delete_symbol(map->dso, sym); > + } > > return 0; > } > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > index 5151a8c0b791..6bf8e74ea1d1 100644 > --- a/tools/perf/util/symbol.c > +++ b/tools/perf/util/symbol.c > @@ -515,6 +515,13 @@ void dso__insert_symbol(struct dso *dso, struct symbol *sym) > } > } > > +void dso__delete_symbol(struct dso *dso, struct symbol *sym) > +{ > + rb_erase_cached(&sym->rb_node, &dso->symbols); > + symbol__delete(sym); > + dso__reset_find_symbol_cache(dso); > +} > + > struct symbol *dso__find_symbol(struct dso *dso, u64 addr) > { > if (dso->last_find_result.addr != addr || dso->last_find_result.symbol == NULL) { > diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h > index 03e264a27cd3..60345691db09 100644 > --- a/tools/perf/util/symbol.h > +++ b/tools/perf/util/symbol.h > @@ -130,6 +130,8 @@ int dso__load_kallsyms(struct dso *dso, const char *filename, struct map *map); > > void dso__insert_symbol(struct dso *dso, > struct symbol *sym); > +void dso__delete_symbol(struct dso *dso, > + struct symbol *sym); > > struct symbol *dso__find_symbol(struct dso *dso, u64 addr); > struct symbol *dso__find_symbol_by_name(struct dso *dso, const char *name); > -- > 2.26.2 >