perf sort: Add dynamic headers for perf report columns

Currently the header string for different columns in perf report is
fixed. Some fields of perf sample could have different meaning for
different architectures than the meaning conveyed by the header string.

An example is the new field 'var2_w' of perf_sample_weight structure.
This is presently captured as 'Local INSTR Latency' in perf mem report.
But this could be used to denote a different latency cycle in another
architecture.

Introduce a weak function arch_perf_header_entry() to set the arch
specific header string for the fields which can contain dynamic header.
If the architecture do not have this function, fall back to the default
header string value.
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Link: https://lore.kernel.org/r/1616425047-1666-3-git-send-email-atrajeev@linux.vnet.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/event.h

@@ -427,5 +427,6 @@ char *get_page_size_name(u64 size, char *str);
 
 void arch_perf_parse_sample_weight(struct perf_sample *data, const __u64 *array, u64 type);
 void arch_perf_synthesize_sample_weight(const struct perf_sample *data, __u64 *array, u64 type);
+const char *arch_perf_header_entry(const char *se_header);
 
 #endif /* __PERF_RECORD_H */

tools/perf/util/sort.c

@@ -25,6 +25,7 @@
 #include <traceevent/event-parse.h>
 #include "mem-events.h"
 #include "annotate.h"
+#include "event.h"
 #include "time-utils.h"
 #include "cgroup.h"
 #include "machine.h"
@@ -45,6 +46,7 @@ const char	*field_order;
 regex_t		ignore_callees_regex;
 int		have_ignore_callees = 0;
 enum sort_mode	sort__mode = SORT_MODE__NORMAL;
+const char	*dynamic_headers[] = {"local_ins_lat"};
 
 /*
  * Replaces all occurrences of a char used with the:
@@ -1816,6 +1818,16 @@ struct sort_dimension {
 	int			taken;
 };
 
+const char * __weak arch_perf_header_entry(const char *se_header)
+{
+	return se_header;
+}
+
+static void sort_dimension_add_dynamic_header(struct sort_dimension *sd)
+{
+	sd->entry->se_header = arch_perf_header_entry(sd->entry->se_header);
+}
+
 #define DIM(d, n, func) [d] = { .name = n, .entry = &(func) }
 
 static struct sort_dimension common_sort_dimensions[] = {
@@ -2739,7 +2751,7 @@ int sort_dimension__add(struct perf_hpp_list *list, const char *tok,
 			struct evlist *evlist,
 			int level)
 {
-	unsigned int i;
+	unsigned int i, j;
 
 	for (i = 0; i < ARRAY_SIZE(common_sort_dimensions); i++) {
 		struct sort_dimension *sd = &common_sort_dimensions[i];
@@ -2747,6 +2759,11 @@ int sort_dimension__add(struct perf_hpp_list *list, const char *tok,
 		if (strncasecmp(tok, sd->name, strlen(tok)))
 			continue;
 
+		for (j = 0; j < ARRAY_SIZE(dynamic_headers); j++) {
+			if (!strcmp(dynamic_headers[j], sd->name))
+				sort_dimension_add_dynamic_header(sd);
+		}
+
 		if (sd->entry == &sort_parent) {
 			int ret = regcomp(&parent_regex, parent_pattern, REG_EXTENDED);
 			if (ret) {