perf test: Expand user space event reading (rdpmc) tests

JIRA: https://issues.redhat.com/browse/RHEL-78200

upstream
========
commit 588d22b
Author: Ian Rogers <irogers@google.com>
Date: Fri Jun 13 17:45:28 2025 -0700

description
===========
Test that disabling rdpmc support via /sys/bus/event_source/cpu*/rdpmc
disables reading in the mmap (libperf read support will fallback to
using a system call).
Test all hybrid PMUs support rdpmc.
Ensure hybrid PMUs use the correct CPU to rdpmc the correct
event. Previously the test would open cycles or instructions with no
extended type then rdpmc it on whatever CPU. This could fail/skip due
to which CPU the test was scheduled upon.

    Signed-off-by: Ian Rogers <irogers@google.com>
    Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
    Link: https://lore.kernel.org/r/20250614004528.1652860-1-irogers@google.com
    Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Signed-off-by: Anubhav Shelat <ashelat@redhat.com>

Author: AnubhavS1

tools/perf/tests/mmap-basic.c

@@ -1,15 +1,18 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <errno.h>
+#include <fcntl.h>
 #include <inttypes.h>
 #include <stdlib.h>
 #include <perf/cpumap.h>
 
+#include "cpumap.h"
 #include "debug.h"
 #include "event.h"
 #include "evlist.h"
 #include "evsel.h"
 #include "thread_map.h"
 #include "tests.h"
+#include "util/affinity.h"
 #include "util/mmap.h"
 #include "util/sample.h"
 #include <linux/err.h>
@@ -172,120 +175,232 @@ static int test__basic_mmap(struct test_suite *test __maybe_unused, int subtest
 	return err;
 }
 
-static int test_stat_user_read(int event)
-{
-	struct perf_counts_values counts = { .val = 0 };
-	struct perf_thread_map *threads;
-	struct perf_evsel *evsel;
-	struct perf_event_mmap_page *pc;
-	struct perf_event_attr attr = {
-		.type	= PERF_TYPE_HARDWARE,
-		.config	= event,
-#ifdef __aarch64__
-		.config1 = 0x2,		/* Request user access */
-#endif
-	};
-	int err, i, ret = TEST_FAIL;
-	bool opened = false, mapped = false;
+enum user_read_state {
+	USER_READ_ENABLED,
+	USER_READ_DISABLED,
+	USER_READ_UNKNOWN,
+};
 
-	threads = perf_thread_map__new_dummy();
-	TEST_ASSERT_VAL("failed to create threads", threads);
+static enum user_read_state set_user_read(struct perf_pmu *pmu, enum user_read_state enabled)
+{
+	char buf[2] = {0, '\n'};
+	ssize_t len;
+	int events_fd, rdpmc_fd;
+	enum user_read_state old_user_read = USER_READ_UNKNOWN;
+
+	if (enabled == USER_READ_UNKNOWN)
+		return USER_READ_UNKNOWN;
+
+	events_fd = perf_pmu__event_source_devices_fd();
+	if (events_fd < 0)
+		return USER_READ_UNKNOWN;
+
+	rdpmc_fd = perf_pmu__pathname_fd(events_fd, pmu->name, "rdpmc", O_RDWR);
+	if (rdpmc_fd < 0) {
+		close(events_fd);
+		return USER_READ_UNKNOWN;
+	}
 
-	perf_thread_map__set_pid(threads, 0, 0);
+	len = read(rdpmc_fd, buf, sizeof(buf));
+	if (len != sizeof(buf))
+		pr_debug("%s read failed\n", __func__);
 
-	evsel = perf_evsel__new(&attr);
-	TEST_ASSERT_VAL("failed to create evsel", evsel);
+	// Note, on Intel hybrid disabling on 1 PMU will implicitly disable on
+	// all the core PMUs.
+	old_user_read = (buf[0] == '1') ? USER_READ_ENABLED : USER_READ_DISABLED;
 
-	err = perf_evsel__open(evsel, NULL, threads);
-	if (err) {
-		pr_err("failed to open evsel: %s\n", strerror(-err));
-		ret = TEST_SKIP;
-		goto out;
+	if (enabled != old_user_read) {
+		buf[0] = (enabled == USER_READ_ENABLED) ? '1' : '0';
+		len = write(rdpmc_fd, buf, sizeof(buf));
+		if (len != sizeof(buf))
+			pr_debug("%s write failed\n", __func__);
 	}
-	opened = true;
+	close(rdpmc_fd);
+	close(events_fd);
+	return old_user_read;
+}
 
-	err = perf_evsel__mmap(evsel, 0);
-	if (err) {
-		pr_err("failed to mmap evsel: %s\n", strerror(-err));
-		goto out;
+static int test_stat_user_read(u64 event, enum user_read_state enabled)
+{
+	struct perf_pmu *pmu = NULL;
+	struct perf_thread_map *threads = perf_thread_map__new_dummy();
+	int ret = TEST_OK;
+
+	pr_err("User space counter reading %" PRIu64 "\n", event);
+	if (!threads) {
+		pr_err("User space counter reading [Failed to create threads]\n");
+		return TEST_FAIL;
 	}
-	mapped = true;
+	perf_thread_map__set_pid(threads, 0, 0);
 
-	pc = perf_evsel__mmap_base(evsel, 0, 0);
-	if (!pc) {
-		pr_err("failed to get mmapped address\n");
-		goto out;
-	}
+	while ((pmu = perf_pmus__scan_core(pmu)) != NULL) {
+		enum user_read_state saved_user_read_state = set_user_read(pmu, enabled);
+		struct perf_event_attr attr = {
+			.type	= PERF_TYPE_HARDWARE,
+			.config	= perf_pmus__supports_extended_type()
+			? event | ((u64)pmu->type << PERF_PMU_TYPE_SHIFT)
+				: event,
+#ifdef __aarch64__
+			.config1 = 0x2,		/* Request user access */
+#endif
+		};
+		struct perf_evsel *evsel = NULL;
+		int err;
+		struct perf_event_mmap_page *pc;
+		bool mapped = false, opened = false, rdpmc_supported;
+		struct perf_counts_values counts = { .val = 0 };
+
+
+		pr_debug("User space counter reading for PMU %s\n", pmu->name);
+		/*
+		 * Restrict scheduling to only use the rdpmc on the CPUs the
+		 * event can be on. If the test doesn't run on the CPU of the
+		 * event then the event will be disabled and the pc->index test
+		 * will fail.
+		 */
+		if (pmu->cpus != NULL)
+			cpu_map__set_affinity(pmu->cpus);
+
+		/* Make the evsel. */
+		evsel = perf_evsel__new(&attr);
+		if (!evsel) {
+			pr_err("User space counter reading for PMU %s [Failed to allocate evsel]\n",
+				pmu->name);
+			ret = TEST_FAIL;
+			goto cleanup;
+		}
 
-	if (!pc->cap_user_rdpmc || !pc->index) {
-		pr_err("userspace counter access not %s\n",
-			!pc->cap_user_rdpmc ? "supported" : "enabled");
-		ret = TEST_SKIP;
-		goto out;
-	}
-	if (pc->pmc_width < 32) {
-		pr_err("userspace counter width not set (%d)\n", pc->pmc_width);
-		goto out;
-	}
+		err = perf_evsel__open(evsel, NULL, threads);
+		if (err) {
+			pr_err("User space counter reading for PMU %s [Failed to open evsel]\n",
+				pmu->name);
+			ret = TEST_SKIP;
+			goto cleanup;
+		}
+		opened = true;
+		err = perf_evsel__mmap(evsel, 0);
+		if (err) {
+			pr_err("User space counter reading for PMU %s [Failed to mmap evsel]\n",
+				pmu->name);
+			ret = TEST_FAIL;
+			goto cleanup;
+		}
+		mapped = true;
+
+		pc = perf_evsel__mmap_base(evsel, 0, 0);
+		if (!pc) {
+			pr_err("User space counter reading for PMU %s [Failed to get mmaped address]\n",
+				pmu->name);
+			ret = TEST_FAIL;
+			goto cleanup;
+		}
 
-	perf_evsel__read(evsel, 0, 0, &counts);
-	if (counts.val == 0) {
-		pr_err("failed to read value for evsel\n");
-		goto out;
-	}
+		if (saved_user_read_state == USER_READ_UNKNOWN)
+			rdpmc_supported = pc->cap_user_rdpmc && pc->index;
+		else
+			rdpmc_supported = (enabled == USER_READ_ENABLED);
 
-	for (i = 0; i < 5; i++) {
-		volatile int count = 0x10000 << i;
-		__u64 start, end, last = 0;
+		if (rdpmc_supported && (!pc->cap_user_rdpmc || !pc->index)) {
+			pr_err("User space counter reading for PMU %s [Failed unexpected supported counter access %d %d]\n",
+				pmu->name, pc->cap_user_rdpmc, pc->index);
+			ret = TEST_FAIL;
+			goto cleanup;
+		}
 
-		pr_debug("\tloop = %u, ", count);
+		if (!rdpmc_supported && pc->cap_user_rdpmc) {
+			pr_err("User space counter reading for PMU %s [Failed unexpected unsupported counter access %d]\n",
+				pmu->name, pc->cap_user_rdpmc);
+			ret = TEST_FAIL;
+			goto cleanup;
+		}
+
+		if (rdpmc_supported && pc->pmc_width < 32) {
+			pr_err("User space counter reading for PMU %s [Failed width not set %d]\n",
+				pmu->name, pc->pmc_width);
+			ret = TEST_FAIL;
+			goto cleanup;
+		}
 
 		perf_evsel__read(evsel, 0, 0, &counts);
-		start = counts.val;
+		if (counts.val == 0) {
+			pr_err("User space counter reading for PMU %s [Failed read]\n", pmu->name);
+			ret = TEST_FAIL;
+			goto cleanup;
+		}
 
-		while (count--) ;
+		for (int i = 0; i < 5; i++) {
+			volatile int count = 0x10000 << i;
+			__u64 start, end, last = 0;
 
-		perf_evsel__read(evsel, 0, 0, &counts);
-		end = counts.val;
+			pr_debug("\tloop = %u, ", count);
 
-		if ((end - start) < last) {
-			pr_err("invalid counter data: end=%llu start=%llu last= %llu\n",
-				end, start, last);
-			goto out;
-		}
-		last = end - start;
-		pr_debug("count = %llu\n", end - start);
-	}
-	ret = TEST_OK;
+			perf_evsel__read(evsel, 0, 0, &counts);
+			start = counts.val;
+
+			while (count--) ;
 
-out:
-	if (mapped)
-		perf_evsel__munmap(evsel);
-	if (opened)
-		perf_evsel__close(evsel);
-	perf_evsel__delete(evsel);
+			perf_evsel__read(evsel, 0, 0, &counts);
+			end = counts.val;
 
+			if ((end - start) < last) {
+				pr_err("User space counter reading for PMU %s [Failed invalid counter data: end=%llu start=%llu last= %llu]\n",
+					pmu->name, end, start, last);
+				ret = TEST_FAIL;
+				goto cleanup;
+			}
+			last = end - start;
+			pr_debug("count = %llu\n", last);
+		}
+		pr_debug("User space counter reading for PMU %s [Success]\n", pmu->name);
+cleanup:
+		if (mapped)
+			perf_evsel__munmap(evsel);
+		if (opened)
+			perf_evsel__close(evsel);
+		perf_evsel__delete(evsel);
+
+		/* If the affinity was changed, then put it back to all CPUs. */
+		if (pmu->cpus != NULL) {
+			struct perf_cpu_map *cpus = cpu_map__online();
+
+			cpu_map__set_affinity(cpus);
+			perf_cpu_map__put(cpus);
+		}
+		set_user_read(pmu, saved_user_read_state);
+	}
 	perf_thread_map__put(threads);
 	return ret;
 }
 
 static int test__mmap_user_read_instr(struct test_suite *test __maybe_unused,
 				      int subtest __maybe_unused)
 {
-	return test_stat_user_read(PERF_COUNT_HW_INSTRUCTIONS);
+	return test_stat_user_read(PERF_COUNT_HW_INSTRUCTIONS, USER_READ_ENABLED);
 }
 
 static int test__mmap_user_read_cycles(struct test_suite *test __maybe_unused,
 				       int subtest __maybe_unused)
 {
-	return test_stat_user_read(PERF_COUNT_HW_CPU_CYCLES);
+	return test_stat_user_read(PERF_COUNT_HW_CPU_CYCLES, USER_READ_ENABLED);
+}
+
+static int test__mmap_user_read_instr_disabled(struct test_suite *test __maybe_unused,
+					       int subtest __maybe_unused)
+{
+	return test_stat_user_read(PERF_COUNT_HW_INSTRUCTIONS, USER_READ_DISABLED);
+}
+
+static int test__mmap_user_read_cycles_disabled(struct test_suite *test __maybe_unused,
+						int subtest __maybe_unused)
+{
+	return test_stat_user_read(PERF_COUNT_HW_CPU_CYCLES, USER_READ_DISABLED);
 }
 
 static struct test_case tests__basic_mmap[] = {
 	TEST_CASE_REASON("Read samples using the mmap interface",
 			 basic_mmap,
 			 "permissions"),
-	TEST_CASE_REASON("User space counter reading of instructions",
+	TEST_CASE_REASON_EXCLUSIVE("User space counter reading of instructions",
 			 mmap_user_read_instr,
 #if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__) || \
 			 (defined(__riscv) && __riscv_xlen == 64)
@@ -294,13 +409,31 @@ static struct test_case tests__basic_mmap[] = {
 			 "unsupported"
 #endif
 		),
-	TEST_CASE_REASON("User space counter reading of cycles",
+	TEST_CASE_REASON_EXCLUSIVE("User space counter reading of cycles",
 			 mmap_user_read_cycles,
 #if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__) || \
 			 (defined(__riscv) && __riscv_xlen == 64)
 			 "permissions"
 #else
 			 "unsupported"
+#endif
+		),
+	TEST_CASE_REASON_EXCLUSIVE("User space counter disabling instructions",
+			 mmap_user_read_instr_disabled,
+#if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__) || \
+			 (defined(__riscv) && __riscv_xlen == 64)
+			 "permissions"
+#else
+			 "unsupported"
+#endif
+		),
+	TEST_CASE_REASON_EXCLUSIVE("User space counter disabling cycles",
+			 mmap_user_read_cycles_disabled,
+#if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__) || \
+			 (defined(__riscv) && __riscv_xlen == 64)
+			 "permissions"
+#else
+			 "unsupported"
 #endif
 		),
 	{	.name = NULL, }

tools/perf/tests/tests.h

@@ -71,6 +71,15 @@ struct test_suite {
 		.exclusive = true,			\
 	}
 
+#define TEST_CASE_REASON_EXCLUSIVE(description, _name, _reason)	\
+	{						\
+		.name = #_name,				\
+		.desc = description,			\
+		.run_case = test__##_name,		\
+		.skip_reason = _reason,			\
+		.exclusive = true,			\
+	}
+
 #define DEFINE_SUITE(description, _name)		\
 	struct test_case tests__##_name[] = {           \
 		TEST_CASE(description, _name),		\