Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755762AbbHYN1x (ORCPT ); Tue, 25 Aug 2015 09:27:53 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:28232 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751978AbbHYN1w (ORCPT ); Tue, 25 Aug 2015 09:27:52 -0400 From: Wang Nan To: CC: , , , , Subject: [PATCH 1/2] perf probe: Prevent segfault when reading probe point with absolute address Date: Tue, 25 Aug 2015 13:27:35 +0000 Message-ID: <1440509256-193590-1-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.193.248] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2350 Lines: 74 'perf probe -l' panic if there is a manually inserted probing point with absolute address. For example: # echo 'p:probe/abs_ffffffff811e6615 0xffffffff811e6615' > /sys/kernel/debug/tracing/kprobe_events # perf probe -l Segmentation fault (core dumped) This patch fix this problem by considering the situation that "tp->symbol == NULL" in find_perf_probe_point_from_dwarf() and find_perf_probe_point_from_map(). After this patch: # perf probe -l probe:abs_ffffffff811e6615 (on SyS_write+5@fs/read_write.c) And when debug info is missing: # rm -rf ~/.debug # mv /lib/modules/4.2.0-rc1+/build/vmlinux /lib/modules/4.2.0-rc1+/build/vmlinux.bak # perf probe -l probe:abs_ffffffff811e6615 (on sys_write+5) Signed-off-by: Wang Nan Cc: Arnaldo Carvalho de Melo Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Namhyung Kim --- tools/perf/util/probe-event.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index f07374b..6c7e538 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -515,7 +515,7 @@ static int find_perf_probe_point_from_dwarf(struct probe_trace_point *tp, if (ret < 0) goto error; addr += stext; - } else { + } else if (tp->symbol) { addr = kernel_get_symbol_address_by_name(tp->symbol, false); if (addr == 0) goto error; @@ -1815,17 +1815,17 @@ static int find_perf_probe_point_from_map(struct probe_trace_point *tp, { struct symbol *sym = NULL; struct map *map; - u64 addr; + u64 addr = tp->address; int ret = -ENOENT; if (!is_kprobe) { map = dso__new_map(tp->module); if (!map) goto out; - addr = tp->address; sym = map__find_symbol(map, addr, NULL); } else { - addr = kernel_get_symbol_address_by_name(tp->symbol, true); + if (tp->symbol) + addr = kernel_get_symbol_address_by_name(tp->symbol, true); if (addr) { addr += tp->offset; sym = __find_kernel_function(addr, &map); -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/