[PATCH perf-tools-next v2 2/4] perf trace: Auto-assign kernel symbol beautifier to function pointer fields

[Aaron Tomlin]

Tracepoint fields that convey kernel function pointers, such as "function",
"fn", "work", "action", and "callsite" are currently formatted as generic
hexadecimal pointers by default.

Enhance syscall_arg_fmt__init_array() to automatically detect these
fields by name and type signature (e.g., typedefs ending with "_func_t"
or "_fn", or C function pointer types containing "(*)") and assign
SCA_KSYM as their default beautifier.

Additionally, register common function pointer field names within the
sorted syscall_arg_fmts__by_name lookup table. This ensures tracepoint
arguments such as workqueue:workqueue_execute_start.function are
symbolised automatically without requiring explicit per-event
configuration. For example:

    ❯ sudo tools/perf/perf trace --event workqueue:workqueue_execute_end --max-events 2 --show-cpu
         0.000 [000] kworker/u32:15/236682 workqueue:workqueue_execute_end(work: 0xffffffffab2f1420, function: toggle_allocation_gate)
         0.132 [000] kworker/u32:15/236682 workqueue:workqueue_execute_end(work: 0xffff8ac2c1adc010, function: flush_to_ldisc)

Signed-off-by: Aaron Tomlin <atomlin@xxxxxxxxxxx>
---
 tools/perf/builtin-trace.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 003048946503..85abae09d328 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -2198,6 +2198,15 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field
 		    ((len >= 4 && strcmp(field->name + len - 4, "name") == 0) ||
 		     strstr(field->name, "path") != NULL)) {
 			arg->scnprintf = SCA_FILENAME;
+		} else if ((field->type && (strstr(field->type, "(*)") != NULL ||
+					    strstr(field->type, "_func_t") != NULL ||
+					    strstr(field->type, "_fn") != NULL)) ||
+			   (((field->flags & TEP_FIELD_IS_POINTER) || field->size == sizeof(u64)) &&
+			    (strcmp(field->name, "fn") == 0 ||
+			     strcmp(field->name, "function") == 0 ||
+			     strcmp(field->name, "callsite") == 0 ||
+			     strcmp(field->name, "call_site") == 0))) {
+			arg->scnprintf = SCA_KSYM;
 		} else if ((field->flags & TEP_FIELD_IS_POINTER) || strstr(field->name, "addr") ||
 			   field_has_hex_fmt(field, len))
 			arg->scnprintf = SCA_PTR;
-- 
2.55.0