From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933251AbbKMU6k (ORCPT ); Fri, 13 Nov 2015 15:58:40 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:49512 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932964AbbKMU5o (ORCPT ); Fri, 13 Nov 2015 15:57:44 -0500 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Wang Nan , Alexei Starovoitov , Masami Hiramatsu , Zefan Li , pi3orama@163.com, Arnaldo Carvalho de Melo Subject: [PATCH 5/5] perf probe: Clear probe_trace_event when add_probe_trace_event() fails Date: Fri, 13 Nov 2015 17:57:29 -0300 Message-Id: <1447448249-22276-6-git-send-email-acme@kernel.org> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1447448249-22276-1-git-send-email-acme@kernel.org> References: <1447448249-22276-1-git-send-email-acme@kernel.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wang Nan When probing with a glob, errors in add_probe_trace_event() won't be passed to debuginfo__find_trace_events() because it would be modified by probe_point_search_cb(). It causes a segfault if perf fails to find an argument for a probe point matched by the glob. For example: # ./perf probe -v -n 'SyS_dup? oldfd' probe-definition(0): SyS_dup? oldfd symbol:SyS_dup? file:(null) line:0 offset:0 return:0 lazy:(null) parsing arg: oldfd into oldfd 1 arguments Looking at the vmlinux_path (7 entries long) Using /lib/modules/4.3.0-rc4+/build/vmlinux for symbols Open Debuginfo file: /lib/modules/4.3.0-rc4+/build/vmlinux Try to find probe point from debuginfo. Matched function: SyS_dup3 found inline addr: 0xffffffff812095c0 Probe point found: SyS_dup3+0 Searching 'oldfd' variable in context. Converting variable oldfd into trace event. oldfd type is long int. found inline addr: 0xffffffff812096d4 Probe point found: SyS_dup2+36 Searching 'oldfd' variable in context. Failed to find 'oldfd' in this function. Matched function: SyS_dup3 Probe point found: SyS_dup3+0 Searching 'oldfd' variable in context. Converting variable oldfd into trace event. oldfd type is long int. Matched function: SyS_dup2 Probe point found: SyS_dup2+0 Searching 'oldfd' variable in context. Converting variable oldfd into trace event. oldfd type is long int. Found 4 probe_trace_events. Opening /sys/kernel/debug/tracing//kprobe_events write=1 Writing event: p:probe/SyS_dup3 _text+2135488 oldfd=%di:s64 Segmentation fault (core dumped) # This patch ensures that add_probe_trace_event() doesn't touches tf->ntevs and tf->tevs if those functions fail. After the patch: # perf probe 'SyS_dup? oldfd' Failed to find 'oldfd' in this function. Added new events: probe:SyS_dup3 (on SyS_dup? with oldfd) probe:SyS_dup3_1 (on SyS_dup? with oldfd) probe:SyS_dup2 (on SyS_dup? with oldfd) You can now use it in all perf tools, such as: perf record -e probe:SyS_dup2 -aR sleep 1 Signed-off-by: Wang Nan Tested-by: Arnaldo Carvalho de Melo Cc: Alexei Starovoitov Cc: Masami Hiramatsu Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1447417761-156094-3-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-finder.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index 63993d7e0fac..05012bb178d7 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -1183,7 +1183,7 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf) container_of(pf, struct trace_event_finder, pf); struct perf_probe_point *pp = &pf->pev->point; struct probe_trace_event *tev; - struct perf_probe_arg *args; + struct perf_probe_arg *args = NULL; int ret, i; /* Check number of tevs */ @@ -1198,19 +1198,23 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf) ret = convert_to_trace_point(&pf->sp_die, tf->mod, pf->addr, pp->retprobe, pp->function, &tev->point); if (ret < 0) - return ret; + goto end; tev->point.realname = strdup(dwarf_diename(sc_die)); - if (!tev->point.realname) - return -ENOMEM; + if (!tev->point.realname) { + ret = -ENOMEM; + goto end; + } pr_debug("Probe point found: %s+%lu\n", tev->point.symbol, tev->point.offset); /* Expand special probe argument if exist */ args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS); - if (args == NULL) - return -ENOMEM; + if (args == NULL) { + ret = -ENOMEM; + goto end; + } ret = expand_probe_args(sc_die, pf, args); if (ret < 0) @@ -1234,6 +1238,10 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf) } end: + if (ret) { + clear_probe_trace_event(tev); + tf->ntevs--; + } free(args); return ret; } -- 2.1.0