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perf trace: Fix noise and signed formatting of __probe_ip in bare dynamic probes

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When a dynamic probe is created without explicitly requested arguments
via perf probe --add, the Ftrace subsystem automatically appends
"__probe_ip" to the tracepoint format to record the instruction pointer.

Currently, perf trace prints this implicit field by default.
Furthermore, because the formatting logic defaults to a standard signed
integer representation, the kernel space memory address is erroneously
displayed as a meaningless negative integer.

    ❯ sudo ./perf trace --event probe:proc_sys_open --max-events 1
         0.000 ps/1316543 probe:proc_sys_open(__probe_ip: -1406056956)

This patch addresses the user experience by combining two refinements:
    1. "__probe_ip" is now hidden from the standard output, as its
       presence adds no contextual value for a bare probe.

    2. If the user explicitly requests verbose output (--verbose),
       "__probe_ip" is intercepted and properly formatted as a hexadecimal
       kernel address, restoring its utility for debugging inline
       function hits.

    ❯ sudo ./perf trace --event probe:proc_sys_open --max-events 1
         0.000 ps/1314074 probe:proc_sys_open()

    ❯ sudo ./perf trace --verbose --event probe:proc_sys_open --max-events 1
    Using CPUID GenuineIntel-6-8E-C
    mmap size 528384B
         0.000 ps/1314366 probe:proc_sys_open(__probe_ip: 0xffffffffac314604)

Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Daniel Vacek <neelx@suse.com>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sean Ashe <sean@ashe.io>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Aaron Tomlin 2026-06-12 18:56:10 -04:00 committed by Arnaldo Carvalho de Melo
parent 190c454638
commit cd355f6dc7
1 changed files with 21 additions and 0 deletions
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21
tools/perf/builtin-trace.c
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@ -3261,6 +3261,27 @@ static size_t trace__fprintf_tp_fields(struct trace *trace, struct perf_sample *
if (val == 0 && !trace->show_zeros && !arg->show_zero && arg->strtoul != STUL_BTF_TYPE)
continue;
/*
* __probe_ip is implicitly added to bare dynamic probes.
* Suppress it by default to avoid cluttering the output.
* If verbose mode is enabled, ensure it is formatted as a
* hexadecimal memory address rather than a signed integer.
*/
if (!strcmp(field->name, "__probe_ip")) {
if (!verbose)
continue;
printed += scnprintf(bf + printed, size - printed,
"%s", printed ? ", " : "");
if (trace->show_arg_names)
printed += scnprintf(bf + printed, size - printed,
"%s: ", field->name);
printed += scnprintf(bf + printed, size - printed, "%#016llx",
(unsigned long long)val);
continue;
}
printed += scnprintf(bf + printed, size - printed, "%s", printed ? ", " : "");
if (trace->show_arg_names)