Since several local symbols can have same name (e.g. t_show),
we need to use the actual address instead of symbol name for
those points. Note that this works only with debuginfo.
E.g. without this change;
----
# ./perf probe -a t_show \$vars
Added new events:
probe:t_show (on t_show with $vars)
probe:t_show_1 (on t_show with $vars)
probe:t_show_2 (on t_show with $vars)
probe:t_show_3 (on t_show with $vars)
You can now use it in all perf tools, such as:
perf record -e probe:t_show_3 -aR sleep 1
----
OK, we have 4 different t_show()s. All functions have
different arguments as below;
----
# cat /sys/kernel/debug/tracing/kprobe_events
p:probe/t_show t_show m=%di:u64 v=%si:u64
p:probe/t_show_1 t_show m=%di:u64 v=%si:u64 t=%si:u64
p:probe/t_show_2 t_show m=%di:u64 v=%si:u64 fmt=%si:u64
p:probe/t_show_3 t_show m=%di:u64 v=%si:u64 file=%si:u64
----
However, all of them have been put on the *same* address.
----
# cat /sys/kernel/debug/kprobes/list
ffffffff810d9720 k t_show+0x0 [DISABLED]
ffffffff810d9720 k t_show+0x0 [DISABLED]
ffffffff810d9720 k t_show+0x0 [DISABLED]
ffffffff810d9720 k t_show+0x0 [DISABLED]
----
With this change;
----
# ./perf probe -a t_show \$vars
Added new events:
probe:t_show (on t_show with $vars)
probe:t_show_1 (on t_show with $vars)
probe:t_show_2 (on t_show with $vars)
probe:t_show_3 (on t_show with $vars)
You can now use it in all perf tools, such as:
perf record -e probe:t_show_3 -aR sleep 1
# cat /sys/kernel/debug/tracing/kprobe_events
p:probe/t_show 0xffffffff810d9720 m=%di:u64 v=%si:u64
p:probe/t_show_1 0xffffffff810e2e40 m=%di:u64 v=%si:u64 t=%si:u64
p:probe/t_show_2 0xffffffff810ece30 m=%di:u64 v=%si:u64 fmt=%si:u64
p:probe/t_show_3 0xffffffff810f4ad0 m=%di:u64 v=%si:u64 file=%si:u64
# cat /sys/kernel/debug/kprobes/list
ffffffff810e2e40 k t_show+0x0 [DISABLED]
ffffffff810ece30 k t_show+0x0 [DISABLED]
ffffffff810f4ad0 k t_show+0x0 [DISABLED]
ffffffff810d9720 k t_show+0x0 [DISABLED]
----
This time, each event is put in different address
correctly.
Note that currently this doesn't support address-based
probe on modules (thus the probes on modules are symbol
based), since it requires relative address probe syntax
for kprobe-tracer, and it doesn't implemented yet.
One more note, this allows us to put events on correct
address, but --list option should be updated to show
correct corresponding source code.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
---
tools/perf/util/probe-event.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 2fb4486..92ab688 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1529,20 +1529,27 @@ char *synthesize_probe_trace_command(struct
probe_trace_event *tev)
if (buf == NULL)
return NULL;
- if (tev->uprobes)
- len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s:%s",
- tp->retprobe ? 'r' : 'p',
- tev->group, tev->event,
+ len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s ", tp->retprobe ? 'r' : 'p',
+ tev->group, tev->event);
+ if (len <= 0)
+ goto error;
+
+ /* Use the real address, except for kernel modules */
+ if (tp->address && !(tp->module && !tev->uprobes))
+ ret = e_snprintf(buf + len, MAX_CMDLEN, "%s%s0x%lx",
+ tp->module ?: "", tp->module ? ":" : "",
+ tp->address);
+ else if (tev->uprobes)
+ ret = e_snprintf(buf + len, MAX_CMDLEN, "%s:%s",
tp->module, tp->symbol);
else
- len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s%s%s+%lu",
- tp->retprobe ? 'r' : 'p',
- tev->group, tev->event,
+ ret = e_snprintf(buf + len, MAX_CMDLEN, "%s%s%s+%lu",
tp->module ?: "", tp->module ? ":" : "",
tp->symbol, tp->offset);
- if (len <= 0)
+ if (ret <= 0)
goto error;
+ len += ret;
for (i = 0; i < tev->nargs; i++) {
ret = synthesize_probe_trace_arg(&tev->args[i], buf + len,
--
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