path: root/mm/damon/dbgfs.c

// SPDX-License-Identifier: GPL-2.0
/*
 * DAMON Debugfs Interface
 *
 * Author: SeongJae Park <sj@kernel.org>
 */

#define pr_fmt(fmt) "damon-dbgfs: " fmt

#include <linux/damon.h>
#include <linux/debugfs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/page_idle.h>
#include <linux/slab.h>

#define DAMON_DBGFS_DEPRECATION_NOTICE					\
	"DAMON debugfs interface is deprecated, so users should move "	\
	"to DAMON_SYSFS. If you cannot, please report your usecase to "	\
	"damon@lists.linux.dev and linux-mm@kvack.org.\n"

static struct damon_ctx **dbgfs_ctxs;
static int dbgfs_nr_ctxs;
static struct dentry **dbgfs_dirs;
static DEFINE_MUTEX(damon_dbgfs_lock);

static void damon_dbgfs_warn_deprecation(void)
{
	pr_warn_once(DAMON_DBGFS_DEPRECATION_NOTICE);
}

/*
 * Returns non-empty string on success, negative error code otherwise.
 */
static char *user_input_str(const char __user *buf, size_t count, loff_t *ppos)
{
	char *kbuf;
	ssize_t ret;

	/* We do not accept continuous write */
	if (*ppos)
		return ERR_PTR(-EINVAL);

	kbuf = kmalloc(count + 1, GFP_KERNEL | __GFP_NOWARN);
	if (!kbuf)
		return ERR_PTR(-ENOMEM);

	ret = simple_write_to_buffer(kbuf, count + 1, ppos, buf, count);
	if (ret != count) {
		kfree(kbuf);
		return ERR_PTR(-EIO);
	}
	kbuf[ret] = '\0';

	return kbuf;
}

static ssize_t dbgfs_attrs_read(struct file *file,
		char __user *buf, size_t count, loff_t *ppos)
{
	struct damon_ctx *ctx = file->private_data;
	char kbuf[128];
	int ret;

	mutex_lock(&ctx->kdamond_lock);
	ret = scnprintf(kbuf, ARRAY_SIZE(kbuf), "%lu %lu %lu %lu %lu\n",
			ctx->attrs.sample_interval, ctx->attrs.aggr_interval,
			ctx->attrs.ops_update_interval,
			ctx->attrs.min_nr_regions, ctx->attrs.max_nr_regions);
	mutex_unlock(&ctx->kdamond_lock);

	return simple_read_from_buffer(buf, count, ppos, kbuf, ret);
}

static ssize_t dbgfs_attrs_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos)
{
	struct damon_ctx *ctx = file->private_data;
	struct damon_attrs attrs;
	char *kbuf;
	ssize_t ret;

	kbuf = user_input_str(buf, count, ppos);
	if (IS_ERR(kbuf))
		return PTR_ERR(kbuf);

	if (sscanf(kbuf, "%lu %lu %lu %lu %lu",
				&attrs.sample_interval, &attrs.aggr_interval,
				&attrs.ops_update_interval,
				&attrs.min_nr_regions,
				&attrs.max_nr_regions) != 5) {
		ret = -EINVAL;
		goto out;
	}

	mutex_lock(&ctx->kdamond_lock);
	if (ctx->kdamond) {
		ret = -EBUSY;
		goto unlock_out;
	}

	ret = damon_set_attrs(ctx, &attrs);
	if (!ret)
		ret = count;
unlock_out:
	mutex_unlock(&ctx->kdamond_lock);
out:
	kfree(kbuf);
	return ret;
}

/*
 * Return corresponding dbgfs' scheme action value (int) for the given
 * damos_action if the given damos_action value is valid and supported by
 * dbgfs, negative error code otherwise.
 */
static int damos_action_to_dbgfs_scheme_action(enum damos_action action)
{
	switch (action) {
	case DAMOS_WILLNEED:
		return 0;
	case DAMOS_COLD:
		return 1;
	case DAMOS_PAGEOUT:
		return 2;
	case DAMOS_HUGEPAGE:
		return 3;
	case DAMOS_NOHUGEPAGE:
		return 4;
	case DAMOS_STAT:
		return 5;
	default:
		return -EINVAL;
	}
}

static ssize_t sprint_schemes(struct damon_ctx *c, char *buf, ssize_t len)
{
	struct damos *s;
	int written = 0;
	int rc;

	damon_for_each_scheme(s, c) {
		rc = scnprintf(&buf[written], len - written,
				"%lu %lu %u %u %u %u %d %lu %lu %lu %u %u %u %d %lu %lu %lu %lu %lu %lu %lu %lu %lu\n",
				s->pattern.min_sz_region,
				s->pattern.max_sz_region,
				s