Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755219AbbHZJog (ORCPT ); Wed, 26 Aug 2015 05:44:36 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:48490 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751816AbbHZJoc (ORCPT ); Wed, 26 Aug 2015 05:44:32 -0400 Message-ID: <55DD8A59.6040708@huawei.com> Date: Wed, 26 Aug 2015 17:43:53 +0800 From: "Wangnan (F)" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: =?UTF-8?B?5bmz5p2+6ZuF5bezIC8gSElSQU1BVFXvvIxNQVNBTUk=?= , "acme@kernel.org" , "rostedt@goodmis.org" CC: "mingo@redhat.com" , "namhyung@kernel.org" , "linux-kernel@vger.kernel.org" , "pi3orama@163.com" , sysp-manager Subject: Re: [PATCH v2 2/4] perf probe: Fix list result when address is zero References: <1440574825-221187-1-git-send-email-wangnan0@huawei.com> <1440574825-221187-3-git-send-email-wangnan0@huawei.com> <50399556C9727B4D88A595C8584AAB37524EC6F0@GSjpTKYDCembx32.service.hitachi.net> In-Reply-To: <50399556C9727B4D88A595C8584AAB37524EC6F0@GSjpTKYDCembx32.service.hitachi.net> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.111.66.109] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5205 Lines: 152 On 2015/8/26 17:29, 平松雅巳 / HIRAMATU，MASAMI wrote: >> From: Wang Nan [mailto:wangnan0@huawei.com] >> >> When manually added uprobe point with zero address, 'perf probe -l' >> reports error. For example: >> >> # echo p:probe_libc/abs_0 /path/to/lib.bin:0x0 arg1=%ax > \ >> /sys/kernel/debug/tracing/uprobe_events >> >> # perf probe -l >> Error: Failed to show event list. >> >> Probing at 0x0 is possible and useful when lib.bin is not a normal >> shared object but is manually mapped. However, in this case kernel >> report: >> >> # cat /sys/kernel/debug/tracing/uprobe_events >> p:probe_libc/abs_0 /tmp/oxygen_root/lib64/libc-2.18.so:0x (null) arg1=%ax >> >> This patch supports the above kernel output. > Former part is OK to me. > >> In addition, this patch also fixes convert_to_perf_probe_point() that, >> if failed to find probe point from both of dwarf and map, in all cases >> pp->function should be filled with a strdup() result, or the following >> ENOMEM error code is incorrect. Remove !tp->module && !is_kprobe >> condition so always use address to build function name if symbol is not >> found. > No, I think this should be included in 3/4, since until that perf probe > doesn't support absolute address on kernel. This is for manually introduced probing points. convert_to_perf_probe_point is called by: perf probe -l -> show_perf_probe_events -> __show_perf_probe_events --> convert_to_perf_probe_event If there is a manually inserted probing point there, 'perf probe -l' reports an error. Here is the result if I remove the second part: $ git log --oneline # I'm in 2/4 aae2c2c perf probe: Fix list result when address is zero 931dff5 perf probe: Prevent segfault when reading probe point with absolute address ... $ git diff # remove the second part diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 926bcec..de2c27e 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -1888,7 +1888,7 @@ static int convert_to_perf_probe_point(struct probe_trace_point *tp, if (tp->symbol) { pp->function = strdup(tp->symbol); pp->offset = tp->offset; - } else { + } else if (!tp->module && !is_kprobe) { ret = e_snprintf(buf, 128, "0x%" PRIx64, (u64)tp->address); if (ret < 0) return ret; ... # echo 'p:probe_libc/abs_5 /lib64/libc.so.6:0x5' > /sys/kernel/debug/tracing/uprobe_events # cat /sys/kernel/debug/tracing/uprobe_events p:probe_libc/abs_5 /lib64/libc.so.6:0x0000000000000005 # perf probe -l Error: Failed to show event list Then add it back: $ git reset --hard HEAD ... # perf probe -l probe_libc:abs_5 (on 0x5 in /lib64/libc.so.6) Thank you. > Thank you, > >> Signed-off-by: Wang Nan >> Cc: Arnaldo Carvalho de Melo >> Cc: Ingo Molnar >> Cc: Masami Hiramatsu >> Cc: Namhyung Kim >> Cc: Steven Rostedt >> --- >> tools/perf/util/probe-event.c | 30 ++++++++++++++++++++++++++---- >> 1 file changed, 26 insertions(+), 4 deletions(-) >> >> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c >> index ef325a2..3ce223d 100644 >> --- a/tools/perf/util/probe-event.c >> +++ b/tools/perf/util/probe-event.c >> @@ -1521,9 +1521,31 @@ int parse_probe_trace_command(const char *cmd, struct probe_trace_event *tev) >> } else >> p = argv[1]; >> fmt1_str = strtok_r(p, "+", &fmt); >> - if (fmt1_str[0] == '0') /* only the address started with 0x */ >> - tp->address = strtoul(fmt1_str, NULL, 0); >> - else { >> + /* only the address started with 0x */ >> + if (fmt1_str[0] == '0') { >> + /* >> + * Fix a special case: >> + * if address == 0, kernel reports something like: >> + * p:probe_libc/abs_0 /lib/libc-2.18.so:0x (null) arg1=%ax >> + * Newer kernel may fix that, but we want to >> + * support old kernel also. >> + */ >> + if (strcmp(fmt1_str, "0x") == 0) { >> + if (!argv[2] || strcmp(argv[2], "(null)")) { >> + ret = -EINVAL; >> + goto out; >> + } >> + tp->address = 0; >> + >> + free(argv[2]); >> + for (i = 2; argv[i + 1] != NULL; i++) >> + argv[i] = argv[i + 1]; >> + >> + argv[i] = NULL; >> + argc -= 1; >> + } else >> + tp->address = strtoul(fmt1_str, NULL, 0); >> + } else { >> /* Only the symbol-based probe has offset */ >> tp->symbol = strdup(fmt1_str); >> if (tp->symbol == NULL) { >> @@ -1868,7 +1890,7 @@ static int convert_to_perf_probe_point(struct probe_trace_point *tp, >> if (tp->symbol) { >> pp->function = strdup(tp->symbol); >> pp->offset = tp->offset; >> - } else if (!tp->module && !is_kprobe) { >> + } else { >> ret = e_snprintf(buf, 128, "0x%" PRIx64, (u64)tp->address); >> if (ret < 0) >> return ret; >> -- >> 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/