path: root/arch/s390/kernel/perf_cpum_cf.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Performance event support for s390x - CPU-measurement Counter Facility
 *
 *  Copyright IBM Corp. 2012, 2021
 *  Author(s): Hendrik Brueckner <brueckner@linux.ibm.com>
 *	       Thomas Richter <tmricht@linux.ibm.com>
 */
#define KMSG_COMPONENT	"cpum_cf"
#define pr_fmt(fmt)	KMSG_COMPONENT ": " fmt

#include <linux/kernel.h>
#include <linux/kernel_stat.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/miscdevice.h>

#include <asm/cpu_mcf.h>
#include <asm/hwctrset.h>
#include <asm/debug.h>

static unsigned int cfdiag_cpu_speed;	/* CPU speed for CF_DIAG trailer */
static debug_info_t *cf_dbg;

#define	CF_DIAG_CTRSET_DEF		0xfeef	/* Counter set header mark */
						/* interval in seconds */

/* Counter sets are stored as data stream in a page sized memory buffer and
 * exported to user space via raw data attached to the event sample data.
 * Each counter set starts with an eight byte header consisting of:
 * - a two byte eye catcher (0xfeef)
 * - a one byte counter set number
 * - a two byte counter set size (indicates the number of counters in this set)
 * - a three byte reserved value (must be zero) to make the header the same
 *   size as a counter value.
 * All counter values are eight byte in size.
 *
 * All counter sets are followed by a 64 byte trailer.
 * The trailer consists of a: