// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2002-2003 Hewlett-Packard Co
 *               Stephane Eranian <eranian@hpl.hp.com>
 *
 * 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 <eranian@hpl.hp.com>");
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);