1 files changed, 623 insertions, 0 deletions
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
new file mode 100644
index 000000000000..faee070977d8
--- /dev/null
+++ b/mm/damon/dbgfs.c
@@ -0,0 +1,623 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DAMON Debugfs Interface
+ *
+ * Author: SeongJae Park <sjpark@amazon.de>
+ */
+
+#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>
+
+static struct damon_ctx **dbgfs_ctxs;
+static int dbgfs_nr_ctxs;
+static struct dentry **dbgfs_dirs;
+static DEFINE_MUTEX(damon_dbgfs_lock);
+
+/*
+ * 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);
+	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->sample_interval, ctx->aggr_interval,
+			ctx->primitive_update_interval, ctx->min_nr_regions,
+			ctx->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;
+	unsigned long s, a, r, minr, maxr;
+	char *kbuf;
+	ssize_t ret = count;
+	int err;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+
+	if (sscanf(kbuf, "%lu %lu %lu %lu %lu",
+				&s, &a, &r, &minr, &maxr) != 5) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mutex_lock(&ctx->kdamond_lock);
+	if (ctx->kdamond) {
+		ret = -EBUSY;
+		goto unlock_out;
+	}
+
+	err = damon_set_attrs(ctx, s, a, r, minr, maxr);
+	if (err)
+		ret = err;
+unlock_out:
+	mutex_unlock(&ctx->kdamond_lock);
+out:
+	kfree(kbuf);
+	return ret;
+}
+
+static inline bool targetid_is_pid(const struct damon_ctx *ctx)
+{
+	return ctx->primitive.target_valid == damon_va_target_valid;
+}
+
+static ssize_t sprint_target_ids(struct damon_ctx *ctx, char *buf, ssize_t len)
+{
+	struct damon_target *t;
+	unsigned long id;
+	int written = 0;
+	int rc;
+
+	damon_for_each_target(t, ctx) {
+		id = t->id;
+		if (targetid_is_pid(ctx))
+			/* Show pid numbers to debugfs users */
+			id = (unsigned long)pid_vnr((struct pid *)id);
+
+		rc = scnprintf(&buf[written], len - written, "%lu ", id);
+		if (!rc)
+			return -ENOMEM;
+		written += rc;
+	}
+	if (written)
+		written -= 1;
+	written += scnprintf(&buf[written], len - written, "\n");
+	return written;
+}
+
+static ssize_t dbgfs_target_ids_read(struct file *file,
+		char __user *buf, size_t count, loff_t *ppos)
+{
+	struct damon_ctx *ctx = file->private_data;
+	ssize_t len;
+	char ids_buf[320];
+
+	mutex_lock(&ctx->kdamond_lock);
+	len = sprint_target_ids(ctx, ids_buf, 320);
+	mutex_unlock(&ctx->kdamond_lock);
+	if (len < 0)
+		return len;
+
+	return simple_read_from_buffer(buf, count, ppos, ids_buf, len);
+}
+
+/*
+ * Converts a string into an array of unsigned long integers
+ *
+ * Returns an array of unsigned long integers if the conversion success, or
+ * NULL otherwise.
+ */
+static unsigned long *str_to_target_ids(const char *str, ssize_t len,
+					ssize_t *nr_ids)
+{
+	unsigned long *ids;
+	const int max_nr_ids = 32;
+	unsigned long id;
+	int pos = 0, parsed, ret;
+
+	*nr_ids = 0;
+	ids = kmalloc_array(max_nr_ids, sizeof(id), GFP_KERNEL);
+	if (!ids)
+		return NULL;
+	while (*nr_ids < max_nr_ids && pos < len) {
+		ret = sscanf(&str[pos], "%lu%n", &id, &parsed);
+		pos += parsed;
+		if (ret != 1)
+			break;
+		ids[*nr_ids] = id;
+		*nr_ids += 1;
+	}
+
+	return ids;
+}
+
+static void dbgfs_put_pids(unsigned long *ids, int nr_ids)
+{
+	int i;
+
+	for (i = 0; i < nr_ids; i++)
+		put_pid((struct pid *)ids[i]);
+}
+
+static ssize_t dbgfs_target_ids_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	struct damon_ctx *ctx = file->private_data;
+	char *kbuf, *nrs;
+	unsigned long *targets;
+	ssize_t nr_targets;
+	ssize_t ret = count;
+	int i;
+	int err;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+
+	nrs = kbuf;
+
+	targets = str_to_target_ids(nrs, ret, &nr_targets);
+	if (!targets) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	if (targetid_is_pid(ctx)) {
+		for (i = 0; i < nr_targets; i++) {
+			targets[i] = (unsigned long)find_get_pid(
+					(int)targets[i]);
+			if (!targets[i]) {
+				dbgfs_put_pids(targets, i);
+				ret = -EINVAL;
+				goto free_targets_out;
+			}
+		}
+	}
+
+	mutex_lock(&ctx->kdamond_lock);
+	if (ctx->kdamond) {
+		if (targetid_is_pid(ctx))
+			dbgfs_put_pids(targets, nr_targets);
+		ret = -EBUSY;
+		goto unlock_out;
+	}
+
+	err = damon_set_targets(ctx, targets, nr_targets);
+	if (err) {
+		if (targetid_is_pid(ctx))
+			dbgfs_put_pids(targets, nr_targets);
+		ret = err;
+	}
+
+unlock_out:
+	mutex_unlock(&ctx->kdamond_lock);
+free_targets_out:
+	kfree(targets);
+out:
+	kfree(kbuf);
+	return ret;
+}
+
+static ssize_t dbgfs_kdamond_pid_read(struct file *file,
+		char __user *buf, size_t count, loff_t *ppos)
+{
+	struct damon_ctx *ctx = file->private_data;
+	char *kbuf;
+	ssize_t len;
+
+	kbuf = kmalloc(count, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	mutex_lock(&ctx->kdamond_lock);
+	if (ctx->kdamond)
+		len = scnprintf(kbuf, count, "%d\n", ctx->kdamond->pid);
+	else
+		len = scnprintf(kbuf, count, "none\n");
+	mutex_unlock(&ctx->kdamond_lock);
+	if (!len)
+		goto out;
+	len = simple_read_from_buffer(buf, count, ppos, kbuf, len);
+
+out:
+	kfree(kbuf);
+	return len;
+}
+
+static int damon_dbgfs_open(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+
+	return nonseekable_open(inode, file);
+}
+
+static const struct file_operations attrs_fops = {
+	.open = damon_dbgfs_open,
+	.read = dbgfs_attrs_read,
+	.write = dbgfs_attrs_write,
+};
+
+static const struct file_operations target_ids_fops = {
+	.open = damon_dbgfs_open,
+	.read = dbgfs_target_ids_read,
+	.write = dbgfs_target_ids_write,
+};
+
+static const struct file_operations kdamond_pid_fops = {
+	.open = damon_dbgfs_open,
+	.read = dbgfs_kdamond_pid_read,
+};
+
+static void dbgfs_fill_ctx_dir(struct dentry *dir, struct damon_ctx *ctx)
+{
+	const char * const file_names[] = {"attrs", "target_ids",
+		"kdamond_pid"};
+	const struct file_operations *fops[] = {&attrs_fops, &target_ids_fops,
+		&kdamond_pid_fops};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(file_names); i++)
+		debugfs_create_file(file_names[i], 0600, dir, ctx, fops[i]);
+}
+
+static int dbgfs_before_terminate(struct damon_ctx *ctx)
+{
+	struct damon_target *t, *next;
+
+	if (!targetid_is_pid(ctx))
+		return 0;
+
+	damon_for_each_target_safe(t, next, ctx) {
+		put_pid((struct pid *)t->id);
+		damon_destroy_target(t);
+	}
+	return 0;
+}
+
+static struct damon_ctx *dbgfs_new_ctx(void)
+{
+	struct damon_ctx *ctx;
+
+	ctx = damon_new_ctx();
+	if (!ctx)
+		return NULL;
+
+	damon_va_set_primitives(ctx);
+	ctx->callback.before_terminate = dbgfs_before_terminate;
+	return ctx;
+}
+
+static void dbgfs_destroy_ctx(struct damon_ctx *ctx)
+{
+	damon_destroy_ctx(ctx);
+}
+
+/*
+ * Make a context of @name and create a debugfs directory for it.
+ *
+ * This function should be called while holding damon_dbgfs_lock.
+ *
+ * Returns 0 on success, negative error code otherwise.
+ */
+static int dbgfs_mk_context(char *name)
+{
+	struct dentry *root, **new_dirs, *new_dir;
+	struct damon_ctx **new_ctxs, *new_ctx;
+
+	if (damon_nr_running_ctxs())
+		return -EBUSY;
+
+	new_ctxs = krealloc(dbgfs_ctxs, sizeof(*dbgfs_ctxs) *
+			(dbgfs_nr_ctxs + 1), GFP_KERNEL);
+	if (!new_ctxs)
+		return -ENOMEM;
+	dbgfs_ctxs = new_ctxs;
+
+	new_dirs = krealloc(dbgfs_dirs, sizeof(*dbgfs_dirs) *
+			(dbgfs_nr_ctxs + 1), GFP_KERNEL);
+	if (!new_dirs)
+		return -ENOMEM;
+	dbgfs_dirs = new_dirs;
+
+	root = dbgfs_dirs[0];
+	if (!root)
+		return -ENOENT;
+
+	new_dir = debugfs_create_dir(name, root);
+	dbgfs_dirs[dbgfs_nr_ctxs] = new_dir;
+
+	new_ctx = dbgfs_new_ctx();
+	if (!new_ctx) {
+		debugfs_remove(new_dir);
+		dbgfs_dirs[dbgfs_nr_ctxs] = NULL;
+		return -ENOMEM;
+	}
+
+	dbgfs_ctxs[dbgfs_nr_ctxs] = new_ctx;
+	dbgfs_fill_ctx_dir(dbgfs_dirs[dbgfs_nr_ctxs],
+			dbgfs_ctxs[dbgfs_nr_ctxs]);
+	dbgfs_nr_ctxs++;
+
+	return 0;
+}
+
+static ssize_t dbgfs_mk_context_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	char *kbuf;
+	char *ctx_name;
+	ssize_t ret = count;
+	int err;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+	ctx_name = kmalloc(count + 1, GFP_KERNEL);
+	if (!ctx_name) {
+		kfree(kbuf);
+		return -ENOMEM;
+	}
+
+	/* Trim white space */
+	if (sscanf(kbuf, "%s", ctx_name) != 1) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mutex_lock(&damon_dbgfs_lock);
+	err = dbgfs_mk_context(ctx_name);
+	if (err)
+		ret = err;
+	mutex_unlock(&damon_dbgfs_lock);
+
+out:
+	kfree(kbuf);
+	kfree(ctx_name);
+	return ret;
+}
+
+/*
+ * Remove a context of @name and its debugfs directory.
+ *
+ * This function should be called while holding damon_dbgfs_lock.
+ *
+ * Return 0 on success, negative error code otherwise.
+ */
+static int dbgfs_rm_context(char *name)
+{
+	struct dentry *root, *dir, **new_dirs;
+	struct damon_ctx **new_ctxs;
+	int i, j;
+
+	if (damon_nr_running_ctxs())
+		return -EBUSY;
+
+	root = dbgfs_dirs[0];
+	if (!root)
+		return -ENOENT;
+
+	dir = debugfs_lookup(name, root);
+	if (!dir)
+		return -ENOENT;
+
+	new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs),
+			GFP_KERNEL);
+	if (!new_dirs)
+		return -ENOMEM;
+
+	new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs),
+			GFP_KERNEL);
+	if (!new_ctxs) {
+		kfree(new_dirs);
+		return -ENOMEM;
+	}
+
+	for (i = 0, j = 0; i < dbgfs_nr_ctxs; i++) {
+		if (dbgfs_dirs[i] == dir) {
+			debugfs_remove(dbgfs_dirs[i]);
+			dbgfs_destroy_ctx(dbgfs_ctxs[i]);
+			continue;
+		}
+		new_dirs[j] = dbgfs_dirs[i];
+		new_ctxs[j++] = dbgfs_ctxs[i];
+	}
+
+	kfree(dbgfs_dirs);
+	kfree(dbgfs_ctxs);
+
+	dbgfs_dirs = new_dirs;
+	dbgfs_ctxs = new_ctxs;
+	dbgfs_nr_ctxs--;
+
+	return 0;
+}
+
+static ssize_t dbgfs_rm_context_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	char *kbuf;
+	ssize_t ret = count;
+	int err;
+	char *ctx_name;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+	ctx_name = kmalloc(count + 1, GFP_KERNEL);
+	if (!ctx_name) {
+		kfree(kbuf);
+		return -ENOMEM;
+	}
+
+	/* Trim white space */
+	if (sscanf(kbuf, "%s", ctx_name) != 1) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mutex_lock(&damon_dbgfs_lock);
+	err = dbgfs_rm_context(ctx_name);
+	if (err)
+		ret = err;
+	mutex_unlock(&damon_dbgfs_lock);
+
+out:
+	kfree(kbuf);
+	kfree(ctx_name);
+	return ret;
+}
+
+static ssize_t dbgfs_monitor_on_read(struct file *file,
+		char __user *buf, size_t count, loff_t *ppos)
+{
+	char monitor_on_buf[5];
+	bool monitor_on = damon_nr_running_ctxs() != 0;
+	int len;
+
+	len = scnprintf(monitor_on_buf, 5, monitor_on ? "on\n" : "off\n");
+
+	return simple_read_from_buffer(buf, count, ppos, monitor_on_buf, len);
+}
+
+static ssize_t dbgfs_monitor_on_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	ssize_t ret = count;
+	char *kbuf;
+	int err;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+
+	/* Remove white space */
+	if (sscanf(kbuf, "%s", kbuf) != 1) {
+		kfree(kbuf);
+		return -EINVAL;
+	}
+
+	if (!strncmp(kbuf, "on", count))
+		err = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs);
+	else if (!strncmp(kbuf, "off", count))
+		err = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs);
+	else
+		err = -EINVAL;
+
+	if (err)
+		ret = err;
+	kfree(kbuf);
+	return ret;
+}
+
+static const struct file_operations mk_contexts_fops = {
+	.write = dbgfs_mk_context_write,
+};
+
+static const struct file_operations rm_contexts_fops = {
+	.write = dbgfs_rm_context_write,
+};
+
+static const struct file_operations monitor_on_fops = {
+	.read = dbgfs_monitor_on_read,
+	.write = dbgfs_monitor_on_write,
+};
+
+static int __init __damon_dbgfs_init(void)
+{
+	struct dentry *dbgfs_root;
+	const char * const file_names[] = {"mk_contexts", "rm_contexts",
+		"monitor_on"};
+	const struct file_operations *fops[] = {&mk_contexts_fops,
+		&rm_contexts_fops, &monitor_on_fops};
+	int i;
+
+	dbgfs_root = debugfs_create_dir("damon", NULL);
+
+	for (i = 0; i < ARRAY_SIZE(file_names); i++)
+		debugfs_create_file(file_names[i], 0600, dbgfs_root, NULL,
+				fops[i]);
+	dbgfs_fill_ctx_dir(dbgfs_root, dbgfs_ctxs[0]);
+
+	dbgfs_dirs = kmalloc_array(1, sizeof(dbgfs_root), GFP_KERNEL);
+	if (!dbgfs_dirs) {
+		debugfs_remove(dbgfs_root);
+		return -ENOMEM;
+	}
+	dbgfs_dirs[0] = dbgfs_root;
+
+	return 0;
+}
+
+/*
+ * Functions for the initialization
+ */
+
+static int __init damon_dbgfs_init(void)
+{
+	int rc;
+
+	dbgfs_ctxs = kmalloc(sizeof(*dbgfs_ctxs), GFP_KERNEL);
+	if (!dbgfs_ctxs)
+		return -ENOMEM;
+	dbgfs_ctxs[0] = dbgfs_new_ctx();
+	if (!dbgfs_ctxs[0]) {
+		kfree(dbgfs_ctxs);
+		return -ENOMEM;
+	}
+	dbgfs_nr_ctxs = 1;
+
+	rc = __damon_dbgfs_init();
+	if (rc) {
+		kfree(dbgfs_ctxs[0]);
+		kfree(dbgfs_ctxs);
+		pr_err("%s: dbgfs init failed\n", __func__);
+	}
+
+	return rc;
+}
+
+module_init(damon_dbgfs_init);
+
+#include "dbgfs-test.h"