On 2015/8/26 17:29, 平松雅巳 / HIRAMATU，MASAMI wrote:
From: Wang Nan [mailto:[email protected]]
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 <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Steven Rostedt <[email protected]>
---
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
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