Messages in this thread Patch in this message | | | From | He Kuang <> | Subject | [PATCH] perf probe: Fix bug in perf probe with global variables | Date | Sat, 25 Apr 2015 16:08:58 +0800 |
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There are missing curly braces which causes find_variable() return wrong value when probing with global variables.
This problem can be reproduced as following:
$ perf probe -v --add='generic_perform_write global_variable_for_test' ... Try to find probe point from debuginfo. Probe point found: generic_perform_write+0 Searching 'global_variable_for_test' variable in context. An error occurred in debuginfo analysis (-2). Error: Failed to add events. Reason: No such file or directory (Code: -2)
After this patch:
$ perf probe -v --add='generic_perform_write global_variable_for_test' ... Converting variable global_variable_for_test into trace event. global_variable_for_test type is int. Found 1 probe_trace_events. Opening /sys/kernel/debug/tracing/kprobe_events write=1 Added new event: Writing event: p:probe/generic_perform_write _stext+1237464 global_variable_for_test=@global_variable_for_test+0:s32 probe:generic_perform_write (on generic_perform_write with global_variable_for_test)
You can now use it in all perf tools, such as:
perf record -e probe:generic_perform_write -aR sleep 1
Signed-off-by: He Kuang <hekuang@huawei.com> --- tools/perf/util/probe-finder.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index 44554c3..1c3cc07 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -578,10 +578,12 @@ static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf) /* Search child die for local variables and parameters. */ if (!die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) { /* Search again in global variables */ - if (!die_find_variable_at(&pf->cu_die, pf->pvar->var, 0, &vr_die)) + if (!die_find_variable_at(&pf->cu_die, pf->pvar->var, + 0, &vr_die)) { pr_warning("Failed to find '%s' in this function.\n", pf->pvar->var); ret = -ENOENT; + } } if (ret >= 0) ret = convert_variable(&vr_die, pf); -- 1.8.5.2
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