perf_event.c

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/*
 * Performance event support for s390x
 *
 *  Copyright IBM Corp. 2012
 *  Author(s): Hendrik Brueckner <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License (version 2 only)
 * as published by the Free Software Foundation.
 */
#define KMSG_COMPONENT  "perf"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/kernel.h>
#include <linux/perf_event.h>
#include <linux/percpu.h>
#include <linux/export.h>
#include <asm/irq.h>
#include <asm/cpu_mf.h>
#include <asm/lowcore.h>
#include <asm/processor.h>

const char *perf_pmu_name(void)
{
    if (cpum_cf_avail() || cpum_sf_avail())
        return "CPU-measurement facilities (CPUMF)";
    return "pmu";
}
EXPORT_SYMBOL(perf_pmu_name);

int perf_num_counters(void)
{
    int num = 0;

    if (cpum_cf_avail())
        num += PERF_CPUM_CF_MAX_CTR;

    return num;
}
EXPORT_SYMBOL(perf_num_counters);

void perf_event_print_debug(void)
{
    struct cpumf_ctr_info cf_info;
    unsigned long flags;
    int cpu;

    if (!cpum_cf_avail())
        return;

    local_irq_save(flags);

    cpu = smp_processor_id();
    memset(&cf_info, 0, sizeof(cf_info));
    if (!qctri(&cf_info)) {
        pr_info("CPU[%i] CPUM_CF: ver=%u.%u A=%04x E=%04x C=%04x\n",
            cpu, cf_info.cfvn, cf_info.csvn,
            cf_info.auth_ctl, cf_info.enable_ctl, cf_info.act_ctl);
        print_hex_dump_bytes("CPUMF Query: ", DUMP_PREFIX_OFFSET,
                     &cf_info, sizeof(cf_info));
    }

    local_irq_restore(flags);
}

/* See also arch/s390/kernel/traps.c */
static unsigned long __store_trace(struct perf_callchain_entry *entry,
                   unsigned long sp,
                   unsigned long low, unsigned long high)
{
    struct stack_frame *sf;
    struct pt_regs *regs;

    while (1) {
        sp = sp & PSW_ADDR_INSN;
        if (sp < low || sp > high - sizeof(*sf))
            return sp;
        sf = (struct stack_frame *) sp;
        perf_callchain_store(entry, sf->gprs[8] & PSW_ADDR_INSN);
        /* Follow the backchain. */
        while (1) {
            low = sp;
            sp = sf->back_chain & PSW_ADDR_INSN;
            if (!sp)
                break;
            if (sp <= low || sp > high - sizeof(*sf))
                return sp;
            sf = (struct stack_frame *) sp;
            perf_callchain_store(entry,
                         sf->gprs[8] & PSW_ADDR_INSN);
        }
        /* Zero backchain detected, check for interrupt frame. */
        sp = (unsigned long) (sf + 1);
        if (sp <= low || sp > high - sizeof(*regs))
            return sp;
        regs = (struct pt_regs *) sp;
        perf_callchain_store(entry, sf->gprs[8] & PSW_ADDR_INSN);
        low = sp;
        sp = regs->gprs[15];
    }
}

void perf_callchain_kernel(struct perf_callchain_entry *entry,
               struct pt_regs *regs)
{
    unsigned long head;
    struct stack_frame *head_sf;

    if (user_mode(regs))
        return;

    head = regs->gprs[15];
    head_sf = (struct stack_frame *) head;

    if (!head_sf || !head_sf->back_chain)
        return;

    head = head_sf->back_chain;
    head = __store_trace(entry, head, S390_lowcore.async_stack - ASYNC_SIZE,
                 S390_lowcore.async_stack);

    __store_trace(entry, head, S390_lowcore.thread_info,
              S390_lowcore.thread_info + THREAD_SIZE);
}