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[PATCH v3 3/6] perf probe: Fix list result when address is zero

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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 /path/to/lib.bin:0x          (null) arg1=%ax

This patch supports the above kernel output.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
---
 tools/perf/util/probe-event.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index f7bacbb..926bcec 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1519,9 +1519,31 @@ 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) {
-- 
1.8.3.4

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Thread

[PATCH v3 0/6] perf probe, tracing/uprobes: Support probing at absolute address Wang Nan <wangnan0@huawei.com> - 2015-08-26 13:00 +0200
  [PATCH v3 6/6] tracing/uprobes: Do not print '0x (null)' when offset is 0 Wang Nan <wangnan0@huawei.com> - 2015-08-26 13:00 +0200
    [tip:perf/core] tracing/uprobes: Do not print '0x (null)'   when offset is 0 tip-bot for Wang Nan <tipbot@zytor.com> - 2015-08-28 08:50 +0200
  [PATCH v3 2/6] perf probe: Fix list result when symbol can't be found Wang Nan <wangnan0@huawei.com> - 2015-08-26 13:00 +0200
    RE: [PATCH v3 2/6] perf probe: Fix list result when symbol can't be  found 平松雅巳 / HIRAMATU，MASAMI   <masami.hiramatsu.pt@hitachi.com> - 2015-08-26 14:30 +0200
    [tip:perf/core] perf probe: Fix list result when symbol can'  t be found tip-bot for Wang Nan <tipbot@zytor.com> - 2015-08-28 08:50 +0200
  [PATCH v3 5/6] perf probe: Support probing at absolute address Wang Nan <wangnan0@huawei.com> - 2015-08-26 13:00 +0200
    RE: [PATCH v3 5/6] perf probe: Support probing at absolute address 平松雅巳 / HIRAMATU，MASAMI   <masami.hiramatsu.pt@hitachi.com> - 2015-08-26 14:20 +0200
    [tip:perf/core] perf probe: Support probing at absolute address tip-bot for Wang Nan <tipbot@zytor.com> - 2015-08-28 08:50 +0200
  [PATCH v3 4/6] perf probe: Fix error reported when offset without function Wang Nan <wangnan0@huawei.com> - 2015-08-26 13:00 +0200
    RE: [PATCH v3 4/6] perf probe: Fix error reported when offset  without function 平松雅巳 / HIRAMATU，MASAMI   <masami.hiramatsu.pt@hitachi.com> - 2015-08-26 14:30 +0200
    [tip:perf/core] perf probe:   Fix error reported when offset without function tip-bot for Wang Nan <tipbot@zytor.com> - 2015-08-28 08:50 +0200
  [PATCH v3 3/6] perf probe: Fix list result when address is zero Wang Nan <wangnan0@huawei.com> - 2015-08-26 13:10 +0200
    RE: [PATCH v3 3/6] perf probe: Fix list result when address is zero 平松雅巳 / HIRAMATU，MASAMI   <masami.hiramatsu.pt@hitachi.com> - 2015-08-26 14:20 +0200
    [tip:perf/core] perf probe: Fix list result when address is zero tip-bot for Wang Nan <tipbot@zytor.com> - 2015-08-28 08:50 +0200
  Re: [PATCH v3 2/6] perf probe: Fix list result when neither dwarf  nor map can't find symbol "Wangnan (F)" <wangnan0@huawei.com> - 2015-08-26 13:10 +0200
  [PATCH v3 2/6] perf probe: Fix list result when neither dwarf nor map can't find symbol Wang Nan <wangnan0@huawei.com> - 2015-08-26 13:10 +0200

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