perfmon_default_smpl.c

Go to the documentation of this file.

/*
 * Copyright (C) 2002-2003 Hewlett-Packard Co
 *               Stephane Eranian <[email protected]>
 *
 * This file implements the default sampling buffer format
 * for the Linux/ia64 perfmon-2 subsystem.
 */
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/init.h>
#include <asm/delay.h>
#include <linux/smp.h>

#include <asm/perfmon.h>
#include <asm/perfmon_default_smpl.h>

MODULE_AUTHOR("Stephane Eranian <[email protected]>");
MODULE_DESCRIPTION("perfmon default sampling format");
MODULE_LICENSE("GPL");

#define DEFAULT_DEBUG 1

#ifdef DEFAULT_DEBUG
#define DPRINT(a) \
    do { \
        if (unlikely(pfm_sysctl.debug >0)) { printk("%s.%d: CPU%d ", __func__, __LINE__, smp_processor_id()); printk a; } \
    } while (0)

#define DPRINT_ovfl(a) \
    do { \
        if (unlikely(pfm_sysctl.debug > 0 && pfm_sysctl.debug_ovfl >0)) { printk("%s.%d: CPU%d ", __func__, __LINE__, smp_processor_id()); printk a; } \
    } while (0)

#else
#define DPRINT(a)
#define DPRINT_ovfl(a)
#endif

static int
default_validate(struct task_struct *task, unsigned int flags, int cpu, void *data)
{
    pfm_default_smpl_arg_t *arg = (pfm_default_smpl_arg_t*)data;
    int ret = 0;

    if (data == NULL) {
        DPRINT(("[%d] no argument passed\n", task_pid_nr(task)));
        return -EINVAL;
    }

    DPRINT(("[%d] validate flags=0x%x CPU%d\n", task_pid_nr(task), flags, cpu));

    /*
     * must hold at least the buffer header + one minimally sized entry
     */
    if (arg->buf_size < PFM_DEFAULT_SMPL_MIN_BUF_SIZE) return -EINVAL;

    DPRINT(("buf_size=%lu\n", arg->buf_size));

    return ret;
}

static int
default_get_size(struct task_struct *task, unsigned int flags, int cpu, void *data, unsigned long *size)
{
    pfm_default_smpl_arg_t *arg = (pfm_default_smpl_arg_t *)data;

    /*
     * size has been validated in default_validate
     */
    *size = arg->buf_size;

    return 0;
}

static int
default_init(struct task_struct *task, void *buf, unsigned int flags, int cpu, void *data)
{
    pfm_default_smpl_hdr_t *hdr;
    pfm_default_smpl_arg_t *arg = (pfm_default_smpl_arg_t *)data;

    hdr = (pfm_default_smpl_hdr_t *)buf;

    hdr->hdr_version      = PFM_DEFAULT_SMPL_VERSION;
    hdr->hdr_buf_size     = arg->buf_size;
    hdr->hdr_cur_offs     = sizeof(*hdr);
    hdr->hdr_overflows    = 0UL;
    hdr->hdr_count        = 0UL;

    DPRINT(("[%d] buffer=%p buf_size=%lu hdr_size=%lu hdr_version=%u cur_offs=%lu\n",
        task_pid_nr(task),
        buf,
        hdr->hdr_buf_size,
        sizeof(*hdr),
        hdr->hdr_version,
        hdr->hdr_cur_offs));

    return 0;
}

static int
default_handler(struct task_struct *task, void *buf, pfm_ovfl_arg_t *arg, struct pt_regs *regs, unsigned long stamp)
{
    pfm_default_smpl_hdr_t *hdr;
    pfm_default_smpl_entry_t *ent;
    void *cur, *last;
    unsigned long *e, entry_size;
    unsigned int npmds, i;
    unsigned char ovfl_pmd;
    unsigned char ovfl_notify;

    if (unlikely(buf == NULL || arg == NULL|| regs == NULL || task == NULL)) {
        DPRINT(("[%d] invalid arguments buf=%p arg=%p\n", task->pid, buf, arg));
        return -EINVAL;
    }

    hdr         = (pfm_default_smpl_hdr_t *)buf;
    cur         = buf+hdr->hdr_cur_offs;
    last        = buf+hdr->hdr_buf_size;
    ovfl_pmd    = arg->ovfl_pmd;
    ovfl_notify = arg->ovfl_notify;

    /*
     * precheck for sanity
     */
    if ((last - cur) < PFM_DEFAULT_MAX_ENTRY_SIZE) goto full;

    npmds = hweight64(arg->smpl_pmds[0]);

    ent = (pfm_default_smpl_entry_t *)cur;

    prefetch(arg->smpl_pmds_values);

    entry_size = sizeof(*ent) + (npmds << 3);

    /* position for first pmd */
    e = (unsigned long *)(ent+1);

    hdr->hdr_count++;

    DPRINT_ovfl(("[%d] count=%lu cur=%p last=%p free_bytes=%lu ovfl_pmd=%d ovfl_notify=%d npmds=%u\n",
            task->pid,
            hdr->hdr_count,
            cur, last,
            last-cur,
            ovfl_pmd,
            ovfl_notify, npmds));

    /*
     * current = task running at the time of the overflow.
     *
     * per-task mode:
     *  - this is usually the task being monitored.
     *    Under certain conditions, it might be a different task
     *
     * system-wide:
     *  - this is not necessarily the task controlling the session
     */
    ent->pid            = current->pid;
    ent->ovfl_pmd       = ovfl_pmd;
    ent->last_reset_val = arg->pmd_last_reset; //pmd[0].reg_last_reset_val;

    /*
     * where did the fault happen (includes slot number)
     */
    ent->ip = regs->cr_iip | ((regs->cr_ipsr >> 41) & 0x3);

    ent->tstamp    = stamp;
    ent->cpu       = smp_processor_id();
    ent->set       = arg->active_set;
    ent->tgid      = current->tgid;

    /*
     * selectively store PMDs in increasing index number
     */
    if (npmds) {
        unsigned long *val = arg->smpl_pmds_values;
        for(i=0; i < npmds; i++) {
            *e++ = *val++;
        }
    }

    /*
     * update position for next entry
     */
    hdr->hdr_cur_offs += entry_size;
    cur               += entry_size;

    /*
     * post check to avoid losing the last sample
     */
    if ((last - cur) < PFM_DEFAULT_MAX_ENTRY_SIZE) goto full;

    /*
     * keep same ovfl_pmds, ovfl_notify
     */
    arg->ovfl_ctrl.bits.notify_user     = 0;
    arg->ovfl_ctrl.bits.block_task      = 0;
    arg->ovfl_ctrl.bits.mask_monitoring = 0;
    arg->ovfl_ctrl.bits.reset_ovfl_pmds = 1; /* reset before returning from interrupt handler */

    return 0;
full:
    DPRINT_ovfl(("sampling buffer full free=%lu, count=%lu, ovfl_notify=%d\n", last-cur, hdr->hdr_count, ovfl_notify));

    /*
     * increment number of buffer overflow.
     * important to detect duplicate set of samples.
     */
    hdr->hdr_overflows++;

    /*
     * if no notification requested, then we saturate the buffer
     */
    if (ovfl_notify == 0) {
        arg->ovfl_ctrl.bits.notify_user     = 0;
        arg->ovfl_ctrl.bits.block_task      = 0;
        arg->ovfl_ctrl.bits.mask_monitoring = 1;
        arg->ovfl_ctrl.bits.reset_ovfl_pmds = 0;
    } else {
        arg->ovfl_ctrl.bits.notify_user     = 1;
        arg->ovfl_ctrl.bits.block_task      = 1; /* ignored for non-blocking context */
        arg->ovfl_ctrl.bits.mask_monitoring = 1;
        arg->ovfl_ctrl.bits.reset_ovfl_pmds = 0; /* no reset now */
    }
    return -1; /* we are full, sorry */
}

static int
default_restart(struct task_struct *task, pfm_ovfl_ctrl_t *ctrl, void *buf, struct pt_regs *regs)
{
    pfm_default_smpl_hdr_t *hdr;

    hdr = (pfm_default_smpl_hdr_t *)buf;

    hdr->hdr_count    = 0UL;
    hdr->hdr_cur_offs = sizeof(*hdr);

    ctrl->bits.mask_monitoring = 0;
    ctrl->bits.reset_ovfl_pmds = 1; /* uses long-reset values */

    return 0;
}

static int
default_exit(struct task_struct *task, void *buf, struct pt_regs *regs)
{
    DPRINT(("[%d] exit(%p)\n", task_pid_nr(task), buf));
    return 0;
}

static pfm_buffer_fmt_t default_fmt={
    .fmt_name       = "default_format",
    .fmt_uuid       = PFM_DEFAULT_SMPL_UUID,
    .fmt_arg_size       = sizeof(pfm_default_smpl_arg_t),
    .fmt_validate       = default_validate,
    .fmt_getsize        = default_get_size,
    .fmt_init       = default_init,
    .fmt_handler        = default_handler,
    .fmt_restart        = default_restart,
    .fmt_restart_active = default_restart,
    .fmt_exit       = default_exit,
};

static int __init
pfm_default_smpl_init_module(void)
{
    int ret;

    ret = pfm_register_buffer_fmt(&default_fmt);
    if (ret == 0) {
        printk("perfmon_default_smpl: %s v%u.%u registered\n",
            default_fmt.fmt_name,
            PFM_DEFAULT_SMPL_VERSION_MAJ,
            PFM_DEFAULT_SMPL_VERSION_MIN);
    } else {
        printk("perfmon_default_smpl: %s cannot register ret=%d\n",
            default_fmt.fmt_name,
            ret);
    }

    return ret;
}

static void __exit
pfm_default_smpl_cleanup_module(void)
{
    int ret;
    ret = pfm_unregister_buffer_fmt(default_fmt.fmt_uuid);

    printk("perfmon_default_smpl: unregister %s=%d\n", default_fmt.fmt_name, ret);
}

module_init(pfm_default_smpl_init_module);
module_exit(pfm_default_smpl_cleanup_module);