Kernel module has the type DSO_TYPE_USER, the check on dso type in
kernel_get_module_dso() disable openning debuginfo of online kernel
modules.
Problem can be reproduced as:
$ insmod test_bpf.ko
$ perf probe -v -m test_bpf --add='skb_is_nonlinear'
probe-definition(0): skb_is_nonlinear
symbol:skb_is_nonlinear file:(null) line:0 offset:0 return:0 lazy:(null)
0 arguments
Failed to find module test_bpf.
Could not open debuginfo. Try to use symbols.
Failed to find symbol skb_is_nonlinear in test_bpf
Error: Failed to add events. Reason: No such file or directory (Code: -2)
Infact kernel_get_module_dso() function is called in perf-probe, in this
condition, machine->dsos list contains only dsos which is either kmod or
kernel loaded by machine__create_kernel_maps(), so there's no need to
pick away the non-kmod user type dsos.
This patch removes the check.
After this patch:
$ perf probe -v -m test_bpf --add='skb_is_nonlinear'
probe-definition(0): skb_is_nonlinear
symbol:skb_is_nonlinear file:(null) line:0 offset:0 return:0 lazy:(null)
0 arguments
Open Debuginfo file: /lib/modules/4.1.0+/test_bpf.ko
Try to find probe point from debuginfo.
Matched function: skb_is_nonlinear
found inline addr: 0x10ab3
Probe point found: test_bpf_init+585
Found 1 probe_trace_events.
Opening /sys/kernel/debug/tracing/kprobe_events write=1
Added new event:
Writing event: p:probe/skb_is_nonlinear test_bpf:test_bpf_init+585
probe:skb_is_nonlinear (on skb_is_nonlinear in test_bpf)
You can now use it in all perf tools, such as:
perf record -e probe:skb_is_nonlinear -aR sleep 1
Signed-off-by: He Kuang <[email protected]>
---
tools/perf/util/probe-event.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 381f23a..8ad2743 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -275,8 +275,6 @@ static int kernel_get_module_dso(const char *module, struct
dso **pdso)
if (module) {
list_for_each_entry(dso, &host_machine->dsos.head, node) {
- if (!dso->kernel)
- continue;
if (strncmp(dso->short_name + 1, module,
dso->short_name_len - 2) == 0)
goto found;
--
1.8.5.2
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