[PATCH v16 2/4] pmu: support reading ARM PMU events in runtime

[Tomasz Duszynski <tduszynski@marvell.com>]

Add support for reading ARM PMU events in runtime.

Signed-off-by: Tomasz Duszynski <tduszynski@marvell.com>
---
 app/test/test_pmu.c         |  4 ++
 lib/pmu/meson.build         |  8 ++++
 lib/pmu/pmu_arm64.c         | 94 +++++++++++++++++++++++++++++++++++++
 lib/pmu/rte_pmu.h           |  4 ++
 lib/pmu/rte_pmu_pmc_arm64.h | 30 ++++++++++++
 5 files changed, 140 insertions(+)
 create mode 100644 lib/pmu/pmu_arm64.c
 create mode 100644 lib/pmu/rte_pmu_pmc_arm64.h

diff --git a/app/test/test_pmu.c b/app/test/test_pmu.c
index 464e5068ec..0dc33eeccc 100644
--- a/app/test/test_pmu.c
+++ b/app/test/test_pmu.c
@@ -13,6 +13,10 @@ test_pmu_read(void)
 	int tries = 10, event;
 	uint64_t val = 0;
 
+#if defined(RTE_ARCH_ARM64)
+	name = "cpu_cycles";
+#endif
+
 	if (name == NULL) {
 		printf("PMU not supported on this arch\n");
 		return TEST_SKIPPED;
diff --git a/lib/pmu/meson.build b/lib/pmu/meson.build
index f173b6f55c..94619c63c2 100644
--- a/lib/pmu/meson.build
+++ b/lib/pmu/meson.build
@@ -10,4 +10,12 @@ endif
 headers = files('rte_pmu.h')
 sources = files('rte_pmu.c')
 
+indirect_headers += files(
+        'rte_pmu_pmc_arm64.h',
+)
+
+if dpdk_conf.has('RTE_ARCH_ARM64')
+    sources += files('pmu_arm64.c')
+endif
+
 deps += ['log']
diff --git a/lib/pmu/pmu_arm64.c b/lib/pmu/pmu_arm64.c
new file mode 100644
index 0000000000..3b72009cff
--- /dev/null
+++ b/lib/pmu/pmu_arm64.c
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(C) 2024 Marvell International Ltd.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <rte_bitops.h>
+#include <rte_common.h>
+
+#include "pmu_private.h"
+
+#define PERF_USER_ACCESS_PATH "/proc/sys/kernel/perf_user_access"
+
+static int restore_uaccess;
+
+static int
+read_attr_int(const char *path, int *val)
+{
+	char buf[BUFSIZ];
+	int ret, fd;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return -errno;
+
+	ret = read(fd, buf, sizeof(buf));
+	if (ret == -1) {
+		close(fd);
+
+		return -errno;
+	}
+
+	*val = strtol(buf, NULL, 10);
+	close(fd);
+
+	return 0;
+}
+
+static int
+write_attr_int(const char *path, int val)
+{
+	char buf[BUFSIZ];
+	int num, ret, fd;
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1)
+		return -errno;
+
+	num = snprintf(buf, sizeof(buf), "%d", val);
+	ret = write(fd, buf, num);
+	if (ret == -1) {
+		close(fd);
+
+		return -errno;
+	}
+
+	close(fd);
+
+	return 0;
+}
+
+int
+pmu_arch_init(void)
+{
+	int ret;
+
+	ret = read_attr_int(PERF_USER_ACCESS_PATH, &restore_uaccess);
+	if (ret)
+		return ret;
+
+	/* user access already enabled */
+	if (restore_uaccess == 1)
+		return 0;
+
+	return write_attr_int(PERF_USER_ACCESS_PATH, 1);
+}
+
+void
+pmu_arch_fini(void)
+{
+	write_attr_int(PERF_USER_ACCESS_PATH, restore_uaccess);
+}
+
+void
+pmu_arch_fixup_config(uint64_t config[3])
+{
+	/* select 64 bit counters */
+	config[1] |= RTE_BIT64(0);
+	/* enable userspace access */
+	config[1] |= RTE_BIT64(1);
+}
diff --git a/lib/pmu/rte_pmu.h b/lib/pmu/rte_pmu.h
index 06731c866f..6e073f11ea 100644
--- a/lib/pmu/rte_pmu.h
+++ b/lib/pmu/rte_pmu.h
@@ -37,6 +37,10 @@ extern "C" {
 #include <rte_compat.h>
 #include <rte_lcore.h>
 
+#if defined(RTE_ARCH_ARM64)
+#include "rte_pmu_pmc_arm64.h"
+#endif
+
 /** Maximum number of events in a group */
 #define RTE_MAX_NUM_GROUP_EVENTS 8
 
diff --git a/lib/pmu/rte_pmu_pmc_arm64.h b/lib/pmu/rte_pmu_pmc_arm64.h
new file mode 100644
index 0000000000..39165bbc20
--- /dev/null
+++ b/lib/pmu/rte_pmu_pmc_arm64.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2024 Marvell.
+ */
+#ifndef _RTE_PMU_PMC_ARM64_H_
+#define _RTE_PMU_PMC_ARM64_H_
+
+#include <rte_common.h>
+
+static __rte_always_inline uint64_t
+rte_pmu_pmc_read(int index)
+{
+	uint64_t val;
+
+	if (index == 31) {
+		/* CPU Cycles (0x11) must be read via pmccntr_el0 */
+		asm volatile("mrs %0, pmccntr_el0" : "=r" (val));
+	} else {
+		asm volatile(
+			"msr pmselr_el0, %x0\n"
+			"mrs %0, pmxevcntr_el0\n"
+			: "=r" (val)
+			: "rZ" (index)
+		);
+	}
+
+	return val;
+}
+#define rte_pmu_pmc_read rte_pmu_pmc_read
+
+#endif /* _RTE_PMU_PMC_ARM64_H_ */
-- 
2.34.1