/*
 * Copyright © 2015-2016 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *   Robert Bragg <robert@sixbynine.org>
 */

#include <linux/anon_inodes.h>

#include "i915_drv.h"

struct perf_open_properties {
	u32 sample_flags;

	u64 single_context:1;
	u64 ctx_handle;
};

static ssize_t i915_perf_read_locked(struct i915_perf_stream *stream,
				     struct file *file,
				     char __user *buf,
				     size_t count,
				     loff_t *ppos)
{
	/* Note we keep the offset (aka bytes read) separate from any
	 * error status so that the final check for whether we return
	 * the bytes read with a higher precedence than any error (see
	 * comment below) doesn't need to be handled/duplicated in
	 * stream->ops->read() implementations.
	 */
	size_t offset = 0;
	int ret = stream->ops->read(stream, buf, count, &offset);

	/* If we've successfully copied any data then reporting that
	 * takes precedence over any internal error status, so the
	 * data isn't lost.
	 *
	 * For example ret will be -ENOSPC whenever there is more
	 * buffered data than can be copied to userspace, but that's
	 * only interesting if we weren't able to copy some data
	 * because it implies the userspace buffer is too small to
	 * receive a single record (and we never split records).
	 *
	 * Another case with ret == -EFAULT is more of a grey area
	 * since it would seem like bad form for userspace to ask us
	 * to overrun its buffer, but the user knows best:
	 *
	 *   http://yarchive.net/comp/linux/partial_reads_writes.html
	 */
	return offset ?: (ret ?: -EAGAIN);
}

static ssize_t i915_perf_read(struct file *file,
			      char __user *buf,
			      size_t count,
			      loff_t *ppos)
{
	struct i915_perf_stream *stream = file->private_data;
	struct drm_i915_private *dev_priv = stream->dev_priv;
	ssize_t ret;

	if (!(file->f_flags & O_NONBLOCK)) {
		/* Allow false positives from stream->ops->wait_unlocked.
		 */
		do {
			ret = stream->ops->wait_unlocked(stream);
			if (ret)
				return ret;

			mutex_lock(&dev_priv->perf.lock);
			ret = i915_perf_read_locked(stream, file,
						    buf, count, ppos);
			mutex_unlock(&dev_priv->perf.lock);
		} while (ret == -EAGAIN);
	} else {
		mutex_lock(&dev_priv->perf.lock);
		ret = i915_perf_read_locked(stream, file, buf, count, ppos);
		mutex_unlock(&dev_priv->perf.lock);
	}

	return ret;
}

static unsigned int i915_perf_poll_locked(struct i915_perf_stream *stream,
					  struct file *file,
					  poll_table *wait)
{
	unsigned int streams = 0;

	stream->ops->poll_wait(stream, file, wait);

	if (stream->ops->can_read(stream))
		streams |= POLLIN;

	return streams;
}

static unsigned int i915_perf_poll(struct file *file, poll_table *wait)
{
	struct i915_perf_stream *stream = file->private_data;
	struct drm_i915_private *dev_priv = stream->dev_priv;
	int ret;

	mutex_lock(&dev_priv->perf.lock);
	ret = i915_perf_poll_locked(stream, file, wait);
	mutex_unlock(&dev_priv->perf.lock);

	return ret;
}

static void i915_perf_enable_locked(struct i915_perf_stream *stream)
{
	if (stream->enabled)
		return;

	/* Allow stream->ops->enable() to refer to this */
	stream->enabled = true;

	if (stream->ops->enable)
		stream->ops->enable(stream);
}

static void i915_perf_disable_locked(struct i915_perf_stream *stream)
{
	if (!stream->enabled)
		return;

	/* Allow stream->ops->disable() to refer to this */
	stream->enabled = false;

	if (stream->ops->disable)
		stream->ops->disable(stream);
}

static long i915_perf_ioctl_locked(struct i915_perf_stream *stream,
				   unsigned int cmd,
				   unsigned long arg)
{
	switch (cmd) {
	case I915_PERF_IOCTL_ENABLE:
		i915_perf_enable_locked(stream);
		return 0;
	case I915_PERF_IOCTL_DISABLE:
		i915_perf_disable_locked(stream);
		return 0;
	}

	return -EINVAL;
}

static long i915_perf_ioctl(struct file *file,
			    unsigned int cmd,
			    unsigned long arg)
{
	struct i915_perf_stream *stream = file->private_data;
	struct drm_i915_private *dev_priv = stream->dev_priv;
	long ret;

	mutex_lock(&dev_priv->perf.lock);
	ret = i915_perf_ioctl_locked(stream, cmd, arg);
	mutex_unlock(&dev_priv->perf.lock);

	return ret;
}

static void i915_perf_destroy_locked(struct i915_perf_stream *stream)
{
	struct drm_i915_private *dev_priv = stream->dev_priv;

	if (stream->enabled)
		i915_perf_disable_locked(stream);

	if (stream->ops->destroy)
		stream->ops->destroy(stream);

	list_del(&stream->link);

	if (stream->ctx) {
		mutex_lock(&dev_priv->drm.struct_mutex);
		i915_gem_context_put(stream->ctx);
		mutex_unlock(&dev_priv->drm.struct_mutex);
	}

	kfree(stream);
}

static int i915_perf_release(struct inode *inode, struct file *file)
{
	struct i915_perf_stream *stream = file->private_data;
	struct drm_i915_private *dev_priv = stream->dev_priv;

	mutex_lock(&dev_priv->perf.lock);
	i915_perf_destroy_locked(stream);
	mutex_unlock(&dev_priv->perf.lock);

	return 0;
}


static const struct file_operations fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.release	= i915_perf_release,
	.poll		= i915_perf_poll,
	.read		= i915_perf_read,
	.unlocked_ioctl	= i915_perf_ioctl,
};


static struct i915_gem_context *
lookup_context(struct drm_i915_private *dev_priv,
	       struct drm_i915_file_private *file_priv,
	       u32 ctx_user_handle)
{
	struct i915_gem_context *ctx;
	int ret;

	ret = i915_mutex_lock_interruptible(&dev_priv->drm);
	if (ret)
		return ERR_PTR(ret);

	ctx = i915_gem_context_lookup(file_priv, ctx_user_handle);
	if (!IS_ERR(ctx))
		i915_gem_context_get(ctx);

	mutex_unlock(&dev_priv->drm.struct_mutex);

	return ctx;
}

static int
i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv,
			    struct drm_i915_perf_open_param *param,
			    struct perf_open_properties *props,
			    struct drm_file *file)
{
	struct i915_gem_context *specific_ctx = NULL;
	struct i915_perf_stream *stream = NULL;
	unsigned long f_flags = 0;
	int stream_fd;
	int ret;

	if (props->single_context) {
		u32 ctx_handle = props->ctx_handle;
		struct drm_i915_file_private *file_priv = file->driver_priv;

		specific_ctx = lookup_context(dev_priv, file_priv, ctx_handle);
		if (IS_ERR(specific_ctx)) {
			ret = PTR_ERR(specific_ctx);
			if (ret != -EINTR)
				DRM_ERROR("Failed to look up context with ID %u for opening perf stream\n",
					  ctx_handle);
			goto err;
		}
	}

	if (!specific_ctx && !capable(CAP_SYS_ADMIN)) {
		DRM_ERROR("Insufficient privileges to open system-wide i915 perf stream\n");
		ret = -EACCES;
		goto err_ctx;
	}

	stream = kzalloc(sizeof(*stream), GFP_KERNEL);
	if (!stream) {
		ret = -ENOMEM;
		goto err_ctx;
	}

	stream->sample_flags = props->sample_flags;
	stream->dev_priv = dev_priv;
	stream->ctx = specific_ctx;

	/*
	 * TODO: support sampling something
	 *
	 * For now this is as far as we can go.
	 */
	DRM_ERROR("Unsupported i915 perf stream configuration\n");
	ret = -EINVAL;
	goto err_alloc;

	list_add(&stream->link, &dev_priv->perf.streams);

	if (param->flags & I915_PERF_FLAG_FD_CLOEXEC)
		f_flags |= O_CLOEXEC;
	if (param->flags & I915_PERF_FLAG_FD_NONBLOCK)
		f_flags |= O_NONBLOCK;

	stream_fd = anon_inode_getfd("[i915_perf]", &fops, stream, f_flags);
	if (stream_fd < 0) {
		ret = stream_fd;
		goto err_open;
	}

	if (!(param->flags & I915_PERF_FLAG_DISABLED))
		i915_perf_enable_locked(stream);

	return stream_fd;

err_open:
	list_del(&stream->link);
	if (stream->ops->destroy)
		stream->ops->destroy(stream);
err_alloc:
	kfree(stream);
err_ctx:
	if (specific_ctx) {
		mutex_lock(&dev_priv->drm.struct_mutex);
		i915_gem_context_put(specific_ctx);
		mutex_unlock(&dev_priv->drm.struct_mutex);
	}
err:
	return ret;
}

/* Note we copy the properties from userspace outside of the i915 perf
 * mutex to avoid an awkward lockdep with mmap_sem.
 *
 * Note this function only validates properties in isolation it doesn't
 * validate that the combination of properties makes sense or that all
 * properties necessary for a particular kind of stream have been set.
 */
static int read_properties_unlocked(struct drm_i915_private *dev_priv,
				    u64 __user *uprops,
				    u32 n_props,
				    struct perf_open_properties *props)
{
	u64 __user *uprop = uprops;
	int i;

	memset(props, 0, sizeof(struct perf_open_properties));

	if (!n_props) {
		DRM_ERROR("No i915 perf properties given");
		return -EINVAL;
	}

	/* Considering that ID = 0 is reserved and assuming that we don't
	 * (currently) expect any configurations to ever specify duplicate
	 * values for a particular property ID then the last _PROP_MAX value is
	 * one greater than the maximum number of properties we expect to get
	 * from userspace.
	 */
	if (n_props >= DRM_I915_PERF_PROP_MAX) {
		DRM_ERROR("More i915 perf properties specified than exist");
		return -EINVAL;
	}

	for (i = 0; i < n_props; i++) {
		u64 id, value;
		int ret;

		ret = get_user(id, uprop);
		if (ret)
			return ret;

		ret = get_user(value, uprop + 1);
		if (ret)
			return ret;

		switch ((enum drm_i915_perf_property_id)id) {
		case DRM_I915_PERF_PROP_CTX_HANDLE:
			props->single_context = 1;
			props->ctx_handle = value;
			break;
		default:
			MISSING_CASE(id);
			DRM_ERROR("Unknown i915 perf property ID");
			return -EINVAL;
		}

		uprop += 2;
	}

	return 0;
}

int i915_perf_open_ioctl(struct drm_device *dev, void *data,
			 struct drm_file *file)
{
	struct drm_i915_private *dev_priv = dev->dev_private;
	struct drm_i915_perf_open_param *param = data;
	struct perf_open_properties props;
	u32 known_open_flags;
	int ret;

	if (!dev_priv->perf.initialized) {
		DRM_ERROR("i915 perf interface not available for this system");
		return -ENOTSUPP;
	}

	known_open_flags = I915_PERF_FLAG_FD_CLOEXEC |
			   I915_PERF_FLAG_FD_NONBLOCK |
			   I915_PERF_FLAG_DISABLED;
	if (param->flags & ~known_open_flags) {
		DRM_ERROR("Unknown drm_i915_perf_open_param flag\n");
		return -EINVAL;
	}

	ret = read_properties_unlocked(dev_priv,
				       u64_to_user_ptr(param->properties_ptr),
				       param->num_properties,
				       &props);
	if (ret)
		return ret;

	mutex_lock(&dev_priv->perf.lock);
	ret = i915_perf_open_ioctl_locked(dev_priv, param, &props, file);
	mutex_unlock(&dev_priv->perf.lock);

	return ret;
}

void i915_perf_init(struct drm_i915_private *dev_priv)
{
	INIT_LIST_HEAD(&dev_priv->perf.streams);
	mutex_init(&dev_priv->perf.lock);

	dev_priv->perf.initialized = true;
}

void i915_perf_fini(struct drm_i915_private *dev_priv)
{
	if (!dev_priv->perf.initialized)
		return;

	/* Currently nothing to clean up */

	dev_priv->perf.initialized = false;
}