/* Performance event support for sparc64.
*
* Copyright (C) 2009, 2010 David S. Miller <davem@davemloft.net>
*
* This code is based almost entirely upon the x86 perf event
* code, which is:
*
* Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
* Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
* Copyright (C) 2009 Jaswinder Singh Rajput
* Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter
* Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
*/
#include <linux/perf_event.h>
#include <linux/kprobes.h>
#include <linux/ftrace.h>
#include <linux/kernel.h>
#include <linux/kdebug.h>
#include <linux/mutex.h>
#include <asm/stacktrace.h>
#include <asm/cpudata.h>
#include <asm/uaccess.h>
#include <asm/atomic.h>
#include <asm/nmi.h>
#include <asm/pcr.h>
#include "kstack.h"
/* Sparc64 chips have two performance counters, 32-bits each, with
* overflow interrupts generated on transition from 0xffffffff to 0.
* The counters are accessed in one go using a 64-bit register.
*
* Both counters are controlled using a single control register. The
* only way to stop all sampling is to clear all of the context (user,
* supervisor, hypervisor) sampling enable bits. But these bits apply
* to both counters, thus the two counters can't be enabled/disabled
* individually.
*
* The control register has two event fields, one for each of the two
* counters. It's thus nearly impossible to have one counter going
* while keeping the other one stopped. Therefore it is possible to
* get overflow interrupts for counters not currently "in use" and
* that condition must be checked in the overflow interrupt handler.
*
* So we use a hack, in that we program inactive counters with the
* "sw_count0" and "sw_count1" events. These count how many times
* the instruction "sethi %hi(0xfc000), %g0" is executed. It's an
* unusual way to encode a NOP and therefore will not trigger in
* normal code.
*/
#define MAX_HWEVENTS 2
#define MAX_PERIOD ((1UL << 32) - 1)
#define PIC_UPPER_INDEX 0
#define PIC_LOWER_INDEX 1
#define PIC_NO_INDEX -1
struct cpu_hw_events {
/* Number of events currently scheduled onto this cpu.
* This tells how many entries in the arrays below
* are valid.
*/
int n_events;
/* Number of new events added since the last hw_perf_disable().
* This works because the perf event layer always adds new
* events inside of a perf_{disable,enable}() sequence.
*/
int n_added;
/* Array of events current scheduled on this cpu. */
struct perf_event *event[MAX_HWEVENTS];
/* Array of encoded longs, specifying the %pcr register
* encoding and the mask of PIC counters this even can
* be scheduled on. See perf_event_encode() et al.
*/
unsigned long events[MAX_HWEVENTS];
/* The current counter index assigned to an event. When the
* event hasn't been programmed into the cpu yet, this will
* hold PIC_NO_INDEX. The event->hw.idx value tells us where
* we ought to schedule the event.
*/
int current_idx[MAX_HWEVENTS];
/* Software copy of %pcr register on this cpu. */
u64 pcr;
/* Enabled/disable state. */
int enabled;
};
DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = { .enabled = 1, };
/* An event map describes the characteristics of a performance
* counter event. In particular it gives the encoding as well as
* a mask telling which counters the event can be measured on.
*/
struct perf_event_map {
u16 encoding;