[PATCH v3 09/10] perf: arm64: Add test for userspace counter access on heterogeneous systems

Rob Herring
2020-09-11T21:52:28Z

Userspace counter access only works on heterogeneous systems with some
restrictions. The userspace process must be pinned to a homogeneous
subset of CPUs and must open the corresponding PMU for those CPUs. This
commit adds a test implementing these requirements.

Signed-off-by: Rob Herring <robh@kernel.org>
---
v2:
- Drop all but heterogeneous test as others covered by libperf tests
- Rework to use libperf
---
tools/perf/arch/arm64/include/arch-tests.h | 7 +
tools/perf/arch/arm64/tests/Build | 1 +
tools/perf/arch/arm64/tests/arch-tests.c | 4 +
tools/perf/arch/arm64/tests/user-events.c | 170 +++++++++++++++++++++
4 files changed, 182 insertions(+)
create mode 100644 tools/perf/arch/arm64/tests/user-events.c

diff --git a/tools/perf/arch/arm64/include/arch-tests.h b/tools/perf/arch/arm64/include/arch-tests.h
index 90ec4c8cb880..380ad34a3f09 100644
--- a/tools/perf/arch/arm64/include/arch-tests.h
+++ b/tools/perf/arch/arm64/include/arch-tests.h
@@ -2,11 +2,18 @@
#ifndef ARCH_TESTS_H
#define ARCH_TESTS_H

+#include <linux/compiler.h>
+
#ifdef HAVE_DWARF_UNWIND_SUPPORT
struct thread;
struct perf_sample;
+int test__arch_unwind_sample(struct perf_sample *sample,
+ struct thread *thread);
#endif

extern struct test arch_tests[];
+int test__rd_pinned(struct test __maybe_unused *test,
+ int __maybe_unused subtest);
+

#endif
diff --git a/tools/perf/arch/arm64/tests/Build b/tools/perf/arch/arm64/tests/Build
index a61c06bdb757..3f9a20c17fc6 100644
--- a/tools/perf/arch/arm64/tests/Build
+++ b/tools/perf/arch/arm64/tests/Build
@@ -1,4 +1,5 @@
perf-y += regs_load.o
perf-$(CONFIG_DWARF_UNWIND) += dwarf-unwind.o

+perf-y += user-events.o
perf-y += arch-tests.o
diff --git a/tools/perf/arch/arm64/tests/arch-tests.c b/tools/perf/arch/arm64/tests/arch-tests.c
index 5b1543c98022..80ce7bd3c16d 100644
--- a/tools/perf/arch/arm64/tests/arch-tests.c
+++ b/tools/perf/arch/arm64/tests/arch-tests.c
@@ -10,6 +10,10 @@ struct test arch_tests[] = {
.func = test__dwarf_unwind,
},
#endif
+ {
+ .desc = "Pinned CPU user counter access",
+ .func = test__rd_pinned,
+ },
{
.func = NULL,
},
diff --git a/tools/perf/arch/arm64/tests/user-events.c b/tools/perf/arch/arm64/tests/user-events.c
new file mode 100644
index 000000000000..9cf30adf39d9
--- /dev/null
+++ b/tools/perf/arch/arm64/tests/user-events.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <unistd.h>
+#include <sched.h>
+#include <cpumap.h>
+
+#include <perf/core.h>
+#include <perf/threadmap.h>
+#include <perf/evsel.h>
+
+#include "pmu.h"
+#include "debug.h"
+#include "tests/tests.h"
+#include "arch-tests.h"
+
+static int run_test(struct perf_evsel *evsel)
+{
+ int n;
+ volatile int tmp = 0;
+ u64 delta, i, loops = 1000;
+ struct perf_counts_values counts = { .val = 0 };
+
+ for (n = 0; n < 6; n++) {
+ u64 stamp, now;
+
+ perf_evsel__read(evsel, 0, 0, &counts);
+ stamp = counts.val;
+
+ for (i = 0; i < loops; i++)
+ tmp++;
+
+ perf_evsel__read(evsel, 0, 0, &counts);
+ now = counts.val;
+ loops *= 10;
+
+ delta = now - stamp;
+ pr_debug("%14d: %14llu\n", n, (long long)delta);
+
+ if (!delta)
+ break;
+ }
+ return delta ? 0 : -1;
+}
+
+static struct perf_pmu *pmu_for_cpu(int cpu)
+{
+ int acpu, idx;
+ struct perf_pmu *pmu = NULL;
+
+ while ((pmu = perf_pmu__scan(pmu)) != NULL) {
+ if (pmu->is_uncore)
+ continue;
+ perf_cpu_map__for_each_cpu(acpu, idx, pmu->cpus)
+ if (acpu == cpu)
+ return pmu;
+ }
+ return NULL;
+}
+
+static bool pmu_is_homogeneous(void)
+{
+ int core_cnt = 0;
+ struct perf_pmu *pmu = NULL;
+
+ while ((pmu = perf_pmu__scan(pmu)) != NULL) {
+ if (!pmu->is_uncore && !perf_cpu_map__empty(pmu->cpus))
+ core_cnt++;
+ }
+ return core_cnt == 1;
+}
+
+static int libperf_print(enum libperf_print_level level,
+ const char *fmt, va_list ap)
+{
+ (void)level;
+ return vfprintf(stderr, fmt, ap);
+}
+
+static struct perf_evsel *perf_init(struct perf_event_attr *attr)
+{
+ int err;
+ struct perf_thread_map *threads;
+ struct perf_evsel *evsel;
+
+ libperf_init(libperf_print);
+
+ threads = perf_thread_map__new_dummy();
+ if (!threads) {
+ pr_err("failed to create threads\n");
+ return NULL;
+ }
+
+ perf_thread_map__set_pid(threads, 0, 0);
+
+ evsel = perf_evsel__new(attr);
+ if (!evsel) {
+ pr_err("failed to create evsel\n");
+ goto out_thread;
+ }
+
+ err = perf_evsel__open(evsel, NULL, threads);
+ if (err) {
+ pr_err("failed to open evsel\n");
+ goto out_open;
+ }
+
+ if (!perf_evsel__mmap(evsel)) {
+ pr_err("failed to mmap evsel\n");
+ goto out_mmap;
+ }
+
+ return evsel;
+
+out_mmap:
+ perf_evsel__close(evsel);
+out_open:
+ perf_evsel__delete(evsel);
+out_thread:
+ perf_thread_map__put(threads);
+ return NULL;
+}
+
+int test__rd_pinned(struct test __maybe_unused *test,
+ int __maybe_unused subtest)
+{
+ int cpu, cputmp, ret = -1;
+ struct perf_evsel *evsel;
+ struct perf_event_attr attr = {
+ .config = 0x8, /* Instruction count */
+ .config1 = 0, /* 32-bit counter */
+ .exclude_kernel = 1,
+ };
+ cpu_set_t cpu_set;
+ struct perf_pmu *pmu;
+
+ if (pmu_is_homogeneous())
+ return TEST_SKIP;
+
+ cpu = sched_getcpu();
+ pmu = pmu_for_cpu(cpu);
+ if (!pmu)
+ return -1;
+ attr.type = pmu->type;
+
+ CPU_ZERO(&cpu_set);
+ perf_cpu_map__for_each_cpu(cpu, cputmp, pmu->cpus)
+ CPU_SET(cpu, &cpu_set);
+ if (sched_setaffinity(0, sizeof(cpu_set), &cpu_set) < 0)
+ pr_err("Could not set affinity\n");
+
+ evsel = perf_init(&attr);
+ if (!evsel)
+ return -1;
+
+ perf_cpu_map__for_each_cpu(cpu, cputmp, pmu->cpus) {
+ CPU_ZERO(&cpu_set);
+ CPU_SET(cpu, &cpu_set);
+ if (sched_setaffinity(0, sizeof(cpu_set), &cpu_set) < 0)
+ pr_err("Could not set affinity\n");
+
+ pr_debug("Running on CPU %d\n", cpu);
+
+ ret = run_test(evsel);
+ if (ret)
+ break;
+ }
+
+ perf_evsel__close(evsel);
+ perf_evsel__delete(evsel);
+ return ret;
+}
--
2.25.1