// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2013 Red Hat
 * Author: Rob Clark <robdclark@gmail.com>
 */

/* For debugging crashes, userspace can:
 *
 *   tail -f /sys/kernel/debug/dri/<minor>/rd > logfile.rd
 *
 * to log the cmdstream in a format that is understood by freedreno/cffdump
 * utility.  By comparing the last successfully completed fence #, to the
 * cmdstream for the next fence, you can narrow down which process and submit
 * caused the gpu crash/lockup.
 *
 * Additionally:
 *
 *   tail -f /sys/kernel/debug/dri/<minor>/hangrd > logfile.rd
 *
 * will capture just the cmdstream from submits which triggered a GPU hang.
 *
 * This bypasses drm_debugfs_create_files() mainly because we need to use
 * our own fops for a bit more control.  In particular, we don't want to
 * do anything if userspace doesn't have the debugfs file open.
 *
 * The module-param "rd_full", which defaults to false, enables snapshotting
 * all (non-written) buffers in the submit, rather than just cmdstream bo's.
 * This is useful to capture the contents of (for example) vbo's or textures,
 * or shader programs (if not emitted inline in cmdstream).
 */

#ifdef CONFIG_DEBUG_FS

#include <linux/circ_buf.h>
#include <linux/debugfs.h>
#include <linux/kfifo.h>
#include <linux/uaccess.h>
#include <linux/wait.h>

#include <drm/drm_file.h>

#include "msm_drv.h"
#include "msm_gpu.h"
#include "msm_gem.h"

static bool rd_full = false;
MODULE_PARM_DESC(rd_full, "If true, $debugfs/.../rd will snapshot all buffer contents");
module_param_named(rd_full, rd_full, bool, 0600);

enum rd_sect_type {
        RD_NONE,
        RD_TEST,       /* ascii text */
        RD_CMD,        /* ascii text */
        RD_GPUADDR,    /* u32 gpuaddr, u32 size */
        RD_CONTEXT,    /* raw dump */
        RD_CMDSTREAM,  /* raw dump */
        RD_CMDSTREAM_ADDR, /* gpu addr of cmdstream */
        RD_PARAM,      /* u32 param_type, u32 param_val, u32 bitlen */
        RD_FLUSH,      /* empty, clear previous params */
        RD_PROGRAM,    /* shader program, raw dump */
        RD_VERT_SHADER,
        RD_FRAG_SHADER,
        RD_BUFFER_CONTENTS,
        RD_GPU_ID,
};

#define BUF_SZ 512  /* should be power of 2 */

/* space used: */
#define circ_count(circ) \
        (CIRC_CNT((circ)->head, (circ)->tail, BUF_SZ))
#define circ_count_to_end(circ) \
        (CIRC_CNT_TO_END((circ)->head, (circ)->tail, BUF_SZ))
/* space available: */
#define circ_space(circ) \
        (CIRC_SPACE((circ)->head, (circ)->tail, BUF_SZ))
#define circ_space_to_end(circ) \
        (CIRC_SPACE_TO_END((circ)->head, (circ)->tail, BUF_SZ))

struct msm_rd_state {
        struct drm_device *dev;

        bool open;

        /* current submit to read out: */
        struct msm_gem_submit *submit;

        /* fifo access is synchronized on the producer side by
         * struct_mutex held by submit code (otherwise we could
         * end up w/ cmds logged in different order than they
         * were executed).  And read_lock synchronizes the reads
         */
        struct mutex read_lock;

        wait_queue_head_t fifo_event;
        struct circ_buf fifo;

        char buf[BUF_SZ];
};

static void rd_write(struct msm_rd_state *rd, const void *buf, int sz)
{
        struct circ_buf *fifo = &rd->fifo;
        const char *ptr = buf;

        while (sz > 0) {
                char *fptr = &fifo->buf[fifo->head];
                int n;

                wait_event(rd->fifo_event, circ_space(&rd->fifo) > 0 || !rd->open);
                if (!rd->open)
                        return;

                /* Note that smp_load_acquire() is not strictly required
                 * as CIRC_SPACE_TO_END() does not access the tail more
                 * than once.
                 */
                n = min(sz, circ_space_to_end(&rd->fifo));
                memcpy(fptr, ptr, n);

                smp_store_release(&fifo->head, (fifo->head + n) & (BUF_SZ - 1));
                sz  -= n;
                ptr += n;

                wake_up_all(&rd->fifo_event);
        }
}

static void rd_write_section(struct msm_rd_state *rd,
                enum rd_sect_type type, const void *buf, int sz)
{
        rd_write(rd, &type, 4);
        rd_write(rd, &sz, 4);
        rd_write(rd, buf, sz);
}

static ssize_t rd_read(struct file *file, char __user *buf,
                size_t sz, loff_t *ppos)
{
        struct msm_rd_state *rd = file->private_data;
        struct circ_buf *fifo = &rd->fifo;
        const char *fptr = &fifo->buf[fifo->tail];
        int n = 0, ret = 0;

        mutex_lock(&rd->read_lock);

        ret = wait_event_interruptible(rd->fifo_event,
                        circ_count(&rd->fifo) > 0);
        if (ret)
                goto out;

        /* Note that smp_load_acquire() is not strictly required
         * as CIRC_CNT_TO_END() does not access the head more than
         * once.
         */
        n = min_t(int, sz, circ_count_to_end(&rd->fifo));
        if (copy_to_user(buf, fptr, n)) {
                ret = -EFAULT;
                goto out;
        }

        smp_store_release(&fifo->tail, (fifo->tail + n) & (BUF_SZ - 1));
        *ppos += n;

        wake_up_all(&rd->fifo_event);

out:
        mutex_unlock(&rd->read_lock);
        if (ret)
                return ret;
        return n;
}

static int rd_open(struct inode *inode, struct file *file)
{
        struct msm_rd_state *rd = inode->i_private;
        struct drm_device *dev = rd->dev;
        struct msm_drm_private *priv = dev->dev_private;
        struct msm_gpu *gpu = priv->gpu;
        uint64_t val;
        uint32_t gpu_id;
        int ret = 0;

        mutex_lock(&dev->struct_mutex);

        if (rd->open || !gpu) {
                ret = -EBUSY;
                goto out;
        }

        file->private_data = rd;
        rd->open = true;

        /* the parsing tools need to know gpu-id to know which
         * register database to load.
         */
        gpu->funcs->get_param(gpu, MSM_PARAM_GPU_ID, &val);
        gpu_id = val;

        rd_write_section(rd, RD_GPU_ID, &gpu_id, sizeof(gpu_id));

out:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

static int rd_release(struct inode *inode, struct file *file)
{
        struct msm_rd_state *rd = inode->i_private;

        rd->open = false;
        wake_up_all(&rd->fifo_event);

        return 0;
}


static const struct file_operations rd_debugfs_fops = {
        .owner = THIS_MODULE,
        .open = rd_open,
        .read = rd_read,
        .llseek = no_llseek,
        .release = rd_release,
};


static void rd_cleanup(struct msm_rd_state *rd)
{
        if (!rd)
                return;

        mutex_destroy(&rd->read_lock);
        kfree(rd);
}

static struct msm_rd_state *rd_init(struct drm_minor *minor, const char *name)
{
        struct msm_rd_state *rd;

        rd = kzalloc(sizeof(*rd), GFP_KERNEL);
        if (!rd)
                return ERR_PTR(-ENOMEM);

        rd->dev = minor->dev;
        rd->fifo.buf = rd->buf;

        mutex_init(&rd->read_lock);

        init_waitqueue_head(&rd->fifo_event);

        debugfs_create_file(name, S_IFREG | S_IRUGO, minor->debugfs_root, rd,
                            &rd_debugfs_fops);

        return rd;
}

int msm_rd_debugfs_init(struct drm_minor *minor)
{
        struct msm_drm_private *priv = minor->dev->dev_private;
        struct msm_rd_state *rd;
        int ret;

        /* only create on first minor: */
        if (priv->rd)
                return 0;

        rd = rd_init(minor, "rd");
        if (IS_ERR(rd)) {
                ret = PTR_ERR(rd);
                goto fail;
        }

        priv->rd = rd;

        rd = rd_init(minor, "hangrd");
        if (IS_ERR(rd)) {
                ret = PTR_ERR(rd);
                goto fail;
        }

        priv->hangrd = rd;

        return 0;

fail:
        msm_rd_debugfs_cleanup(priv);
        return ret;
}

void msm_rd_debugfs_cleanup(struct msm_drm_private *priv)
{
        rd_cleanup(priv->rd);
        priv->rd = NULL;

        rd_cleanup(priv->hangrd);
        priv->hangrd = NULL;
}

static void snapshot_buf(struct msm_rd_state *rd,
                struct msm_gem_submit *submit, int idx,
                uint64_t iova, uint32_t size)
{
        struct msm_gem_object *obj = submit->bos[idx].obj;
        unsigned offset = 0;
        const char *buf;

        if (iova) {
                offset = iova - submit->bos[idx].iova;
        } else {
                iova = submit->bos[idx].iova;
                size = obj->base.size;
        }

        /*
         * Always write the GPUADDR header so can get a complete list of all the
         * buffers in the cmd
         */
        rd_write_section(rd, RD_GPUADDR,
                        (uint32_t[3]){ iova, size, iova >> 32 }, 12);

        /* But only dump the contents of buffers marked READ */
        if (!(submit->bos[idx].flags & MSM_SUBMIT_BO_READ))
                return;

        buf = msm_gem_get_vaddr_active(&obj->base);
        if (IS_ERR(buf))
                return;

        buf += offset;

        rd_write_section(rd, RD_BUFFER_CONTENTS, buf, size);

        msm_gem_put_vaddr(&obj->base);
}

static bool
should_dump(struct msm_gem_submit *submit, int idx)
{
        return rd_full || (submit->bos[idx].flags & MSM_SUBMIT_BO_DUMP);
}

/* called under struct_mutex */
void msm_rd_dump_submit(struct msm_rd_state *rd, struct msm_gem_submit *submit,
                const char *fmt, ...)
{
        struct drm_device *dev = submit->dev;
        struct task_struct *task;
        char msg[256];
        int i, n;

        if (!rd->open)
                return;

        /* writing into fifo is serialized by caller, and
         * rd->read_lock is used to serialize the reads
         */
        WARN_ON(!mutex_is_locked(&dev->struct_mutex));

        if (fmt) {
                va_list args;

                va_start(args, fmt);
                n = vscnprintf(msg, sizeof(msg), fmt, args);
                va_end(args);

                rd_write_section(rd, RD_CMD, msg, ALIGN(n, 4));
        }

        rcu_read_lock();
        task = pid_task(submit->pid, PIDTYPE_PID);
        if (task) {
                n = scnprintf(msg, sizeof(msg), "%.*s/%d: fence=%u",
                                TASK_COMM_LEN, task->comm,
                                pid_nr(submit->pid), submit->seqno);
        } else {
                n = scnprintf(msg, sizeof(msg), "???/%d: fence=%u",
                                pid_nr(submit->pid), submit->seqno);
        }
        rcu_read_unlock();

        rd_write_section(rd, RD_CMD, msg, ALIGN(n, 4));

        for (i = 0; i < submit->nr_bos; i++)
                if (should_dump(submit, i))
                        snapshot_buf(rd, submit, i, 0, 0);

        for (i = 0; i < submit->nr_cmds; i++) {
                uint64_t iova = submit->cmd[i].iova;
                uint32_t szd  = submit->cmd[i].size; /* in dwords */

                /* snapshot cmdstream bo's (if we haven't already): */
                if (!should_dump(submit, i)) {
                        snapshot_buf(rd, submit, submit->cmd[i].idx,
                                        submit->cmd[i].iova, szd * 4);
                }

                switch (submit->cmd[i].type) {
                case MSM_SUBMIT_CMD_IB_TARGET_BUF:
                        /* ignore IB-targets, we've logged the buffer, the
                         * parser tool will follow the IB based on the logged
                         * buffer/gpuaddr, so nothing more to do.
                         */
                        break;
                case MSM_SUBMIT_CMD_CTX_RESTORE_BUF:
                case MSM_SUBMIT_CMD_BUF:
                        rd_write_section(rd, RD_CMDSTREAM_ADDR,
                                (uint32_t[3]){ iova, szd, iova >> 32 }, 12);
                        break;
                }
        }
}
#endif