index : wireguard-linux	backport-5.4.y davem/net davem/net-next devel gregkh/stable-5.4.y jd/bump-compilers jd/deferred-aip-removal jd/new-archs jd/orphan-parallel jd/rcu-barrier jd/shorter-socket-lock jd/unified-crypt-queue jd/xdp-l3 stable update-toolchain
	WireGuard for the Linux kernel	Jason A. Donenfeld

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path: root/Documentation/features/debug/kprobes

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Copyright © 1996 – 2026 Jason A. Donenfeld. All Rights Reverse Engineered.

#include <stdio.h>
#include <unistd.h>
#include <linux/types.h>
#include <sys/prctl.h>

#include "parse-events.h"
#include "evlist.h"
#include "evsel.h"
#include "thread_map.h"
#include "cpumap.h"
#include "tsc.h"
#include "tests/tests.h"

#include "arch-tests.h"

#define CHECK__(x) {				\
	while ((x) < 0) {			\
		pr_debug(#x " failed!\n");	\
		goto out_err;			\
	}					\
}

#define CHECK_NOT_NULL__(x) {			\
	while ((x) == NULL) {			\
		pr_debug(#x " failed!\n");	\
		goto out_err;			\
	}					\
}

/**
 * test__perf_time_to_tsc - test converting perf time to TSC.
 *
 * This function implements a test that checks that the conversion of perf time
 * to and from TSC is consistent with the order of events.  If the test passes
 * %0 is returned, otherwise %-1 is returned.  If TSC conversion is not
 * supported then then the test passes but " (not supported)" is printed.
 */
int test__perf_time_to_tsc(void)
{
	struct record_opts opts = {
		.mmap_pages	     = UINT_MAX,
		.user_freq	     = UINT_MAX,
		.user_interval	     = ULLONG_MAX,
		.freq		     = 4000,
		.target		     = {
			.uses_mmap   = true,
		},
		.sample_time	     = true,
	};
	struct thread_map *threads = NULL;
	struct cpu_map *cpus = NULL;
	struct perf_evlist *evlist = NULL;
	struct perf_evsel *evsel = NULL;
	int err = -1, ret, i;
	const char *comm1, *comm2;
	struct perf_tsc_conversion tc;
	struct perf_event_mmap_page *pc;
	union perf_event *event;
	u64 test_tsc, comm1_tsc, comm2_tsc;
	u64 test_time, comm1_time = 0, comm2_time = 0;

	threads = thread_map__new(-1, getpid(), UINT_MAX);
	CHECK_NOT_NULL__(threads);

	cpus = cpu_map__new(NULL);
	CHECK_NOT_NULL__(cpus);

	evlist = perf_evlist__new();
	CHECK_NOT_NULL__(evlist);

	perf_evlist__set_maps(evlist, cpus, threads);

	CHECK__(parse_events(evlist, "cycles:u", NULL));

	perf_evlist__config(evlist, &opts);

	evsel = perf_evlist__first(evlist);

	evsel->attr.comm = 1;
	evsel->attr.disabled = 1;
	evsel->attr.enable_on_exec = 0;

	CHECK__(perf_evlist__open(evlist));

	CHECK__(perf_evlist__mmap(evlist, UINT_MAX, false));

	pc = evlist->mmap[0].base;
	ret = perf_read_tsc_conversion(pc, &tc);
	if (ret) {
		if (ret == -EOPNOTSUPP) {
			fprintf(stderr, " (not supported)");
			return 0;
		}
		goto out_err;
	}

	perf_evlist__enable(evlist);

	comm1 = "Test COMM 1";
	CHECK__(prctl(PR_SET_NAME, (unsigned long)comm1, 0, 0, 0));

	test_tsc = rdtsc();

	comm2 = "Test COMM 2";
	CHECK__(prctl(PR_SET_NAME, (unsigned long)comm2, 0, 0, 0));

	perf_evlist__disable(evlist);

	for (i = 0; i < evlist->nr_mmaps; i++) {
		while ((event = perf_evlist__mmap_read(evlist, i)) != NULL) {
			struct perf_sample sample;

			if (event->header.type != PERF_RECORD_COMM ||
			    (pid_t)event->comm.pid != getpid() ||
			    (pid_t)event->comm.tid != getpid())
				goto next_event;

			if (strcmp(event->comm.comm, comm1) == 0) {
				CHECK__(perf_evsel__parse_sample(evsel, event,
								 &sample));
				comm1_time = sample.time;
			}
			if (strcmp(event->comm.comm, comm2) == 0) {
				CHECK__(perf_evsel__parse_sample(evsel, event,
								 &sample));
				comm2_time = sample.time;
			}
next_event:
			perf_evlist__mmap_consume(evlist, i);
		}
	}

	if (!comm1_time || !comm2_time)
		goto out_err;

	test_time = tsc_to_perf_time(test_tsc, &tc);
	comm1_tsc = perf_time_to_tsc(comm1_time, &tc);
	comm2_tsc = perf_time_to_tsc(comm2_time, &tc);

	pr_debug("1st event perf time %"PRIu64" tsc %"PRIu64"\n",
		 comm1_time, comm1_tsc);
	pr_debug("rdtsc          time %"PRIu64" tsc %"PRIu64"\n",
		 test_time, test_tsc);
	pr_debug("2nd event perf time %"PRIu64" tsc %"PRIu64"\n",
		 comm2_time, comm2_tsc);

	if (test_time <= comm1_time ||
	    test_time >= comm2_time)
		goto out_err;

	if (test_tsc <= comm1_tsc ||
	    test_tsc >= comm2_tsc)
		goto out_err;

	err = 0;

out_err:
	if (evlist) {
		perf_evlist__disable(evlist);
		perf_evlist__delete(evlist);
	}

	return err;
}