[PATCH 2/3] perf trace: Auto-assign kernel symbol beautifier to function pointer fields

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 <[email protected]>
---
 tools/perf/builtin-trace.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index cbc5bdc0cc12..d3401b64340a 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -2090,8 +2090,13 @@ static int syscall__alloc_arg_fmts(struct syscall *sc, int nr_args)
 }
 
 static const struct syscall_arg_fmt syscall_arg_fmts__by_name[] = {
+	{ .name = "action",	.scnprintf = SCA_KSYM, },
+	{ .name = "callsite",	.scnprintf = SCA_KSYM, },
+	{ .name = "fn",		.scnprintf = SCA_KSYM, },
+	{ .name = "function",	.scnprintf = SCA_KSYM, },
 	{ .name = "msr",	.scnprintf = SCA_X86_MSR,	  .strtoul = STUL_X86_MSR,	   },
 	{ .name = "vector",	.scnprintf = SCA_X86_IRQ_VECTORS, .strtoul = STUL_X86_IRQ_VECTORS, },
+	{ .name = "work",	.scnprintf = SCA_KSYM, },
 };
 
 static int syscall_arg_fmt__cmp(const void *name, const void *fmtp)
@@ -2192,6 +2197,14 @@ 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 (strcmp(field->name, "fn") == 0 ||
+			   strcmp(field->name, "function") == 0 ||
+			   strcmp(field->name, "callsite") == 0 ||
+			   strcmp(field->name, "action") == 0 ||
+			   (field->type && (strstr(field->type, "(*)") != NULL ||
+					    strstr(field->type, "_func_t") != NULL ||
+					    strstr(field->type, "_fn") != NULL))) {
+			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