kernel-hacking-2024-linux-steffo/tools/perf/builtin-diff.c

/*
 * builtin-diff.c
 *
 * Builtin diff command: Analyze two perf.data input files, look up and read
 * DSOs and symbol information, sort them and produce a diff.
 */
#include "builtin.h"

#include "util/debug.h"
#include "util/event.h"
#include "util/hist.h"
#include "util/session.h"
#include "util/sort.h"
#include "util/symbol.h"
#include "util/util.h"

#include <stdlib.h>

static char const *input_old = "perf.data.old",
		  *input_new = "perf.data";
static char	  diff__default_sort_order[] = "dso,symbol";
static bool  force;
static bool show_displacement;

static int perf_session__add_hist_entry(struct perf_session *self,
					struct addr_location *al, u64 count)
{
	bool hit;
	struct hist_entry *he = __perf_session__add_hist_entry(&self->hists,
							       al, NULL,
							       count, &hit);
	if (he == NULL)
		return -ENOMEM;

	if (hit)
		he->count += count;

	return 0;
}

static int diff__process_sample_event(event_t *event, struct perf_session *session)
{
	struct addr_location al;
	struct sample_data data = { .period = 1, };

	dump_printf("(IP, %d): %d: %#Lx\n", event->header.misc,
		    event->ip.pid, event->ip.ip);

	if (event__preprocess_sample(event, session, &al, NULL) < 0) {
		pr_warning("problem processing %d event, skipping it.\n",
			   event->header.type);
		return -1;
	}

	if (al.filtered || al.sym == NULL)
		return 0;

	event__parse_sample(event, session->sample_type, &data);

	if (perf_session__add_hist_entry(session, &al, data.period)) {
		pr_warning("problem incrementing symbol count, skipping event\n");
		return -1;
	}

	session->events_stats.total += data.period;
	return 0;
}

static struct perf_event_ops event_ops = {
	.sample	= diff__process_sample_event,
	.mmap	= event__process_mmap,
	.comm	= event__process_comm,
	.exit	= event__process_task,
	.fork	= event__process_task,
	.lost	= event__process_lost,
};

static void perf_session__insert_hist_entry_by_name(struct rb_root *root,
						    struct hist_entry *he)
{
	struct rb_node **p = &root->rb_node;
	struct rb_node *parent = NULL;
	struct hist_entry *iter;

	while (*p != NULL) {
		parent = *p;
		iter = rb_entry(parent, struct hist_entry, rb_node);
		if (hist_entry__cmp(he, iter) < 0)
			p = &(*p)->rb_left;
		else
			p = &(*p)->rb_right;
	}

	rb_link_node(&he->rb_node, parent, p);
	rb_insert_color(&he->rb_node, root);
}

static void perf_session__resort_hist_entries(struct perf_session *self)
{
	unsigned long position = 1;
	struct rb_root tmp = RB_ROOT;
	struct rb_node *next = rb_first(&self->hists);

	while (next != NULL) {
		struct hist_entry *n = rb_entry(next, struct hist_entry, rb_node);

		next = rb_next(&n->rb_node);
		rb_erase(&n->rb_node, &self->hists);
		n->position = position++;
		perf_session__insert_hist_entry_by_name(&tmp, n);
	}

	self->hists = tmp;
}

static void perf_session__set_hist_entries_positions(struct perf_session *self)
{
	perf_session__output_resort(&self->hists, self->events_stats.total);
	perf_session__resort_hist_entries(self);
}

static struct hist_entry *
perf_session__find_hist_entry(struct perf_session *self,
			      struct hist_entry *he)
{
	struct rb_node *n = self->hists.rb_node;

	while (n) {
		struct hist_entry *iter = rb_entry(n, struct hist_entry, rb_node);
		int64_t cmp = hist_entry__cmp(he, iter);

		if (cmp < 0)
			n = n->rb_left;
		else if (cmp > 0)
			n = n->rb_right;
		else 
			return iter;
	}

	return NULL;
}

static void perf_session__match_hists(struct perf_session *old_session,
				      struct perf_session *new_session)
{
	struct rb_node *nd;

	for (nd = rb_first(&new_session->hists); nd; nd = rb_next(nd)) {
		struct hist_entry *pos = rb_entry(nd, struct hist_entry, rb_node);
		pos->pair = perf_session__find_hist_entry(old_session, pos);
	}
}

static int __cmd_diff(void)
{
	int ret, i;
	struct perf_session *session[2];

	session[0] = perf_session__new(input_old, O_RDONLY, force);
	session[1] = perf_session__new(input_new, O_RDONLY, force);
	if (session[0] == NULL || session[1] == NULL)
		return -ENOMEM;

	for (i = 0; i < 2; ++i) {
		ret = perf_session__process_events(session[i], &event_ops);
		if (ret)
			goto out_delete;
	}

	perf_session__output_resort(&session[1]->hists,
				    session[1]->events_stats.total);
	if (show_displacement)
		perf_session__set_hist_entries_positions(session[0]);

	perf_session__match_hists(session[0], session[1]);
	perf_session__fprintf_hists(&session[1]->hists, session[0],
				    show_displacement, stdout,
				    session[1]->events_stats.total);
out_delete:
	for (i = 0; i < 2; ++i)
		perf_session__delete(session[i]);
	return ret;
}

static const char * const diff_usage[] = {
	"perf diff [<options>] [old_file] [new_file]",
	NULL,
};

static const struct option options[] = {
	OPT_INCR('v', "verbose", &verbose,
		    "be more verbose (show symbol address, etc)"),
	OPT_BOOLEAN('m', "displacement", &show_displacement,
		    "Show position displacement relative to baseline"),
	OPT_BOOLEAN('D', "dump-raw-trace", &dump_trace,
		    "dump raw trace in ASCII"),
	OPT_BOOLEAN('f', "force", &force, "don't complain, do it"),
	OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
		    "load module symbols - WARNING: use only with -k and LIVE kernel"),
	OPT_BOOLEAN('P', "full-paths", &symbol_conf.full_paths,
		    "Don't shorten the pathnames taking into account the cwd"),
	OPT_STRING('d', "dsos", &symbol_conf.dso_list_str, "dso[,dso...]",
		   "only consider symbols in these dsos"),
	OPT_STRING('C', "comms", &symbol_conf.comm_list_str, "comm[,comm...]",
		   "only consider symbols in these comms"),
	OPT_STRING('S', "symbols", &symbol_conf.sym_list_str, "symbol[,symbol...]",
		   "only consider these symbols"),
	OPT_STRING('s', "sort", &sort_order, "key[,key2...]",
		   "sort by key(s): pid, comm, dso, symbol, parent"),
	OPT_STRING('t', "field-separator", &symbol_conf.field_sep, "separator",
		   "separator for columns, no spaces will be added between "
		   "columns '.' is reserved."),
	OPT_END()
};

int cmd_diff(int argc, const char **argv, const char *prefix __used)
{
	sort_order = diff__default_sort_order;
	argc = parse_options(argc, argv, options, diff_usage, 0);
	if (argc) {
		if (argc > 2)
			usage_with_options(diff_usage, options);
		if (argc == 2) {
			input_old = argv[0];
			input_new = argv[1];
		} else
			input_new = argv[0];
	}

	symbol_conf.exclude_other = false;
	if (symbol__init() < 0)
		return -1;

	setup_sorting(diff_usage, options);
	setup_pager();

	sort_entry__setup_elide(&sort_dso, symbol_conf.dso_list, "dso", NULL);
	sort_entry__setup_elide(&sort_comm, symbol_conf.comm_list, "comm", NULL);
	sort_entry__setup_elide(&sort_sym, symbol_conf.sym_list, "symbol", NULL);

	return __cmd_diff();
}