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-rw-r--r--mm/damon/dbgfs.c1114
1 files changed, 1114 insertions, 0 deletions
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
new file mode 100644
index 000000000..b3f454a5c
--- /dev/null
+++ b/mm/damon/dbgfs.c
@@ -0,0 +1,1114 @@
+// 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 | __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->pattern.min_nr_accesses,
+ s->pattern.max_nr_accesses,
+ s->pattern.min_age_region,
+ s->pattern.max_age_region,
+ damos_action_to_dbgfs_scheme_action(s->action),
+ s->quota.ms, s->quota.sz,
+ s->quota.reset_interval,
+ s->quota.weight_sz,
+ s->quota.weight_nr_accesses,
+ s->quota.weight_age,
+ s->wmarks.metric, s->wmarks.interval,
+ s->wmarks.high, s->wmarks.mid, s->wmarks.low,
+ s->stat.nr_tried, s->stat.sz_tried,
+ s->stat.nr_applied, s->stat.sz_applied,
+ s->stat.qt_exceeds);
+ if (!rc)
+ return -ENOMEM;
+
+ written += rc;
+ }
+ return written;
+}
+
+static ssize_t dbgfs_schemes_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 | __GFP_NOWARN);
+ if (!kbuf)
+ return -ENOMEM;
+
+ mutex_lock(&ctx->kdamond_lock);
+ len = sprint_schemes(ctx, kbuf, count);
+ mutex_unlock(&ctx->kdamond_lock);
+ if (len < 0)
+ goto out;
+ len = simple_read_from_buffer(buf, count, ppos, kbuf, len);
+
+out:
+ kfree(kbuf);
+ return len;
+}
+
+static void free_schemes_arr(struct damos **schemes, ssize_t nr_schemes)
+{
+ ssize_t i;
+
+ for (i = 0; i < nr_schemes; i++)
+ kfree(schemes[i]);
+ kfree(schemes);
+}
+
+/*
+ * Return corresponding damos_action for the given dbgfs input for a scheme
+ * action if the input is valid, negative error code otherwise.
+ */
+static enum damos_action dbgfs_scheme_action_to_damos_action(int dbgfs_action)
+{
+ switch (dbgfs_action) {
+ case 0:
+ return DAMOS_WILLNEED;
+ case 1:
+ return DAMOS_COLD;
+ case 2:
+ return DAMOS_PAGEOUT;
+ case 3:
+ return DAMOS_HUGEPAGE;
+ case 4:
+ return DAMOS_NOHUGEPAGE;
+ case 5:
+ return DAMOS_STAT;
+ default:
+ return -EINVAL;
+ }
+}
+
+/*
+ * Converts a string into an array of struct damos pointers
+ *
+ * Returns an array of struct damos pointers that converted if the conversion
+ * success, or NULL otherwise.
+ */
+static struct damos **str_to_schemes(const char *str, ssize_t len,
+ ssize_t *nr_schemes)
+{
+ struct damos *scheme, **schemes;
+ const int max_nr_schemes = 256;
+ int pos = 0, parsed, ret;
+ unsigned int action_input;
+ enum damos_action action;
+
+ schemes = kmalloc_array(max_nr_schemes, sizeof(scheme),
+ GFP_KERNEL);
+ if (!schemes)
+ return NULL;
+
+ *nr_schemes = 0;
+ while (pos < len && *nr_schemes < max_nr_schemes) {
+ struct damos_access_pattern pattern = {};
+ struct damos_quota quota = {};
+ struct damos_watermarks wmarks;
+
+ ret = sscanf(&str[pos],
+ "%lu %lu %u %u %u %u %u %lu %lu %lu %u %u %u %u %lu %lu %lu %lu%n",
+ &pattern.min_sz_region, &pattern.max_sz_region,
+ &pattern.min_nr_accesses,
+ &pattern.max_nr_accesses,
+ &pattern.min_age_region,
+ &pattern.max_age_region,
+ &action_input, &quota.ms,
+ &quota.sz, &quota.reset_interval,
+ &quota.weight_sz, &quota.weight_nr_accesses,
+ &quota.weight_age, &wmarks.metric,
+ &wmarks.interval, &wmarks.high, &wmarks.mid,
+ &wmarks.low, &parsed);
+ if (ret != 18)
+ break;
+ action = dbgfs_scheme_action_to_damos_action(action_input);
+ if ((int)action < 0)
+ goto fail;
+
+ if (pattern.min_sz_region > pattern.max_sz_region ||
+ pattern.min_nr_accesses > pattern.max_nr_accesses ||
+ pattern.min_age_region > pattern.max_age_region)
+ goto fail;
+
+ if (wmarks.high < wmarks.mid || wmarks.high < wmarks.low ||
+ wmarks.mid < wmarks.low)
+ goto fail;
+
+ pos += parsed;
+ scheme = damon_new_scheme(&pattern, action, &quota, &wmarks);
+ if (!scheme)
+ goto fail;
+
+ schemes[*nr_schemes] = scheme;
+ *nr_schemes += 1;
+ }
+ return schemes;
+fail:
+ free_schemes_arr(schemes, *nr_schemes);
+ return NULL;
+}
+
+static ssize_t dbgfs_schemes_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = file->private_data;
+ char *kbuf;
+ struct damos **schemes;
+ ssize_t nr_schemes = 0, ret;
+
+ kbuf = user_input_str(buf, count, ppos);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ schemes = str_to_schemes(kbuf, count, &nr_schemes);
+ if (!schemes) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond) {
+ ret = -EBUSY;
+ goto unlock_out;
+ }
+
+ damon_set_schemes(ctx, schemes, nr_schemes);
+ ret = count;
+ nr_schemes = 0;
+
+unlock_out:
+ mutex_unlock(&ctx->kdamond_lock);
+ free_schemes_arr(schemes, nr_schemes);
+out:
+ kfree(kbuf);
+ return ret;
+}
+
+static ssize_t sprint_target_ids(struct damon_ctx *ctx, char *buf, ssize_t len)
+{
+ struct damon_target *t;
+ int id;
+ int written = 0;
+ int rc;
+
+ damon_for_each_target(t, ctx) {
+ if (damon_target_has_pid(ctx))
+ /* Show pid numbers to debugfs users */
+ id = pid_vnr(t->pid);
+ else
+ /* Show 42 for physical address space, just for fun */
+ id = 42;
+
+ rc = scnprintf(&buf[written], len - written, "%d ", 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 integers array
+ *
+ * Returns an array of integers array if the conversion success, or NULL
+ * otherwise.
+ */
+static int *str_to_ints(const char *str, ssize_t len, ssize_t *nr_ints)
+{
+ int *array;
+ const int max_nr_ints = 32;
+ int nr;
+ int pos = 0, parsed, ret;
+
+ *nr_ints = 0;
+ array = kmalloc_array(max_nr_ints, sizeof(*array), GFP_KERNEL);
+ if (!array)
+ return NULL;
+ while (*nr_ints < max_nr_ints && pos < len) {
+ ret = sscanf(&str[pos], "%d%n", &nr, &parsed);
+ pos += parsed;
+ if (ret != 1)
+ break;
+ array[*nr_ints] = nr;
+ *nr_ints += 1;
+ }
+
+ return array;
+}
+
+static void dbgfs_put_pids(struct pid **pids, int nr_pids)
+{
+ int i;
+
+ for (i = 0; i < nr_pids; i++)
+ put_pid(pids[i]);
+}
+
+/*
+ * Converts a string into an struct pid pointers array
+ *
+ * Returns an array of struct pid pointers if the conversion success, or NULL
+ * otherwise.
+ */
+static struct pid **str_to_pids(const char *str, ssize_t len, ssize_t *nr_pids)
+{
+ int *ints;
+ ssize_t nr_ints;
+ struct pid **pids;
+
+ *nr_pids = 0;
+
+ ints = str_to_ints(str, len, &nr_ints);
+ if (!ints)
+ return NULL;
+
+ pids = kmalloc_array(nr_ints, sizeof(*pids), GFP_KERNEL);
+ if (!pids)
+ goto out;
+
+ for (; *nr_pids < nr_ints; (*nr_pids)++) {
+ pids[*nr_pids] = find_get_pid(ints[*nr_pids]);
+ if (!pids[*nr_pids]) {
+ dbgfs_put_pids(pids, *nr_pids);
+ kfree(ints);
+ kfree(pids);
+ return NULL;
+ }
+ }
+
+out:
+ kfree(ints);
+ return pids;
+}
+
+/*
+ * dbgfs_set_targets() - Set monitoring targets.
+ * @ctx: monitoring context
+ * @nr_targets: number of targets
+ * @pids: array of target pids (size is same to @nr_targets)
+ *
+ * This function should not be called while the kdamond is running. @pids is
+ * ignored if the context is not configured to have pid in each target. On
+ * failure, reference counts of all pids in @pids are decremented.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int dbgfs_set_targets(struct damon_ctx *ctx, ssize_t nr_targets,
+ struct pid **pids)
+{
+ ssize_t i;
+ struct damon_target *t, *next;
+
+ damon_for_each_target_safe(t, next, ctx) {
+ if (damon_target_has_pid(ctx))
+ put_pid(t->pid);
+ damon_destroy_target(t);
+ }
+
+ for (i = 0; i < nr_targets; i++) {
+ t = damon_new_target();
+ if (!t) {
+ damon_for_each_target_safe(t, next, ctx)
+ damon_destroy_target(t);
+ if (damon_target_has_pid(ctx))
+ dbgfs_put_pids(pids, nr_targets);
+ return -ENOMEM;
+ }
+ if (damon_target_has_pid(ctx))
+ t->pid = pids[i];
+ damon_add_target(ctx, t);
+ }
+
+ return 0;
+}
+
+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;
+ bool id_is_pid = true;
+ char *kbuf;
+ struct pid **target_pids = NULL;
+ ssize_t nr_targets;
+ ssize_t ret;
+
+ kbuf = user_input_str(buf, count, ppos);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ if (!strncmp(kbuf, "paddr\n", count)) {
+ id_is_pid = false;
+ nr_targets = 1;
+ }
+
+ if (id_is_pid) {
+ target_pids = str_to_pids(kbuf, count, &nr_targets);
+ if (!target_pids) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ }
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond) {
+ if (id_is_pid)
+ dbgfs_put_pids(target_pids, nr_targets);
+ ret = -EBUSY;
+ goto unlock_out;
+ }
+
+ /* remove previously set targets */
+ dbgfs_set_targets(ctx, 0, NULL);
+ if (!nr_targets) {
+ ret = count;
+ goto unlock_out;
+ }
+
+ /* Configure the context for the address space type */
+ if (id_is_pid)
+ ret = damon_select_ops(ctx, DAMON_OPS_VADDR);
+ else
+ ret = damon_select_ops(ctx, DAMON_OPS_PADDR);
+ if (ret)
+ goto unlock_out;
+
+ ret = dbgfs_set_targets(ctx, nr_targets, target_pids);
+ if (!ret)
+ ret = count;
+
+unlock_out:
+ mutex_unlock(&ctx->kdamond_lock);
+ kfree(target_pids);
+out:
+ kfree(kbuf);
+ return ret;
+}
+
+static ssize_t sprint_init_regions(struct damon_ctx *c, char *buf, ssize_t len)
+{
+ struct damon_target *t;
+ struct damon_region *r;
+ int target_idx = 0;
+ int written = 0;
+ int rc;
+
+ damon_for_each_target(t, c) {
+ damon_for_each_region(r, t) {
+ rc = scnprintf(&buf[written], len - written,
+ "%d %lu %lu\n",
+ target_idx, r->ar.start, r->ar.end);
+ if (!rc)
+ return -ENOMEM;
+ written += rc;
+ }
+ target_idx++;
+ }
+ return written;
+}
+
+static ssize_t dbgfs_init_regions_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 | __GFP_NOWARN);
+ if (!kbuf)
+ return -ENOMEM;
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond) {
+ mutex_unlock(&ctx->kdamond_lock);
+ len = -EBUSY;
+ goto out;
+ }
+
+ len = sprint_init_regions(ctx, kbuf, count);
+ mutex_unlock(&ctx->kdamond_lock);
+ if (len < 0)
+ goto out;
+ len = simple_read_from_buffer(buf, count, ppos, kbuf, len);
+
+out:
+ kfree(kbuf);
+ return len;
+}
+
+static int add_init_region(struct damon_ctx *c, int target_idx,
+ struct damon_addr_range *ar)
+{
+ struct damon_target *t;
+ struct damon_region *r, *prev;
+ unsigned long idx = 0;
+ int rc = -EINVAL;
+
+ if (ar->start >= ar->end)
+ return -EINVAL;
+
+ damon_for_each_target(t, c) {
+ if (idx++ == target_idx) {
+ r = damon_new_region(ar->start, ar->end);
+ if (!r)
+ return -ENOMEM;
+ damon_add_region(r, t);
+ if (damon_nr_regions(t) > 1) {
+ prev = damon_prev_region(r);
+ if (prev->ar.end > r->ar.start) {
+ damon_destroy_region(r, t);
+ return -EINVAL;
+ }
+ }
+ rc = 0;
+ }
+ }
+ return rc;
+}
+
+static int set_init_regions(struct damon_ctx *c, const char *str, ssize_t len)
+{
+ struct damon_target *t;
+ struct damon_region *r, *next;
+ int pos = 0, parsed, ret;
+ int target_idx;
+ struct damon_addr_range ar;
+ int err;
+
+ damon_for_each_target(t, c) {
+ damon_for_each_region_safe(r, next, t)
+ damon_destroy_region(r, t);
+ }
+
+ while (pos < len) {
+ ret = sscanf(&str[pos], "%d %lu %lu%n",
+ &target_idx, &ar.start, &ar.end, &parsed);
+ if (ret != 3)
+ break;
+ err = add_init_region(c, target_idx, &ar);
+ if (err)
+ goto fail;
+ pos += parsed;
+ }
+
+ return 0;
+
+fail:
+ damon_for_each_target(t, c) {
+ damon_for_each_region_safe(r, next, t)
+ damon_destroy_region(r, t);
+ }
+ return err;
+}
+
+static ssize_t dbgfs_init_regions_write(struct file *file,
+ const char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ struct damon_ctx *ctx = file->private_data;
+ char *kbuf;
+ ssize_t ret = count;
+ int err;
+
+ kbuf = user_input_str(buf, count, ppos);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond) {
+ ret = -EBUSY;
+ goto unlock_out;
+ }
+
+ err = set_init_regions(ctx, kbuf, ret);
+ if (err)
+ ret = err;
+
+unlock_out:
+ mutex_unlock(&ctx->kdamond_lock);
+ 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 | __GFP_NOWARN);
+ 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 schemes_fops = {
+ .open = damon_dbgfs_open,
+ .read = dbgfs_schemes_read,
+ .write = dbgfs_schemes_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 init_regions_fops = {
+ .open = damon_dbgfs_open,
+ .read = dbgfs_init_regions_read,
+ .write = dbgfs_init_regions_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", "schemes", "target_ids",
+ "init_regions", "kdamond_pid"};
+ const struct file_operations *fops[] = {&attrs_fops, &schemes_fops,
+ &target_ids_fops, &init_regions_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 void dbgfs_before_terminate(struct damon_ctx *ctx)
+{
+ struct damon_target *t, *next;
+
+ if (!damon_target_has_pid(ctx))
+ return;
+
+ mutex_lock(&ctx->kdamond_lock);
+ damon_for_each_target_safe(t, next, ctx) {
+ put_pid(t->pid);
+ damon_destroy_target(t);
+ }
+ mutex_unlock(&ctx->kdamond_lock);
+}
+
+static struct damon_ctx *dbgfs_new_ctx(void)
+{
+ struct damon_ctx *ctx;
+
+ ctx = damon_new_ctx();
+ if (!ctx)
+ return NULL;
+
+ if (damon_select_ops(ctx, DAMON_OPS_VADDR) &&
+ damon_select_ops(ctx, DAMON_OPS_PADDR)) {
+ damon_destroy_ctx(ctx);
+ return NULL;
+ }
+ 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);
+ /* Below check is required for a potential duplicated name case */
+ if (IS_ERR(new_dir))
+ return PTR_ERR(new_dir);
+ 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;
+
+ 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);
+ ret = dbgfs_mk_context(ctx_name);
+ if (!ret)
+ ret = count;
+ 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 inode *inode;
+ struct damon_ctx **new_ctxs;
+ int i, j;
+ int ret = 0;
+
+ if (damon_nr_running_ctxs())
+ return -EBUSY;
+
+ root = dbgfs_dirs[0];
+ if (!root)
+ return -ENOENT;
+
+ dir = debugfs_lookup(name, root);
+ if (!dir)
+ return -ENOENT;
+
+ inode = d_inode(dir);
+ if (!S_ISDIR(inode->i_mode)) {
+ ret = -EINVAL;
+ goto out_dput;
+ }
+
+ new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs),
+ GFP_KERNEL);
+ if (!new_dirs) {
+ ret = -ENOMEM;
+ goto out_dput;
+ }
+
+ new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs),
+ GFP_KERNEL);
+ if (!new_ctxs) {
+ ret = -ENOMEM;
+ goto out_new_dirs;
+ }
+
+ 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--;
+
+ goto out_dput;
+
+out_new_dirs:
+ kfree(new_dirs);
+out_dput:
+ dput(dir);
+ return ret;
+}
+
+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;
+ 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);
+ ret = dbgfs_rm_context(ctx_name);
+ if (!ret)
+ ret = count;
+ 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;
+ char *kbuf;
+
+ 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;
+ }
+
+ mutex_lock(&damon_dbgfs_lock);
+ if (!strncmp(kbuf, "on", count)) {
+ int i;
+
+ for (i = 0; i < dbgfs_nr_ctxs; i++) {
+ if (damon_targets_empty(dbgfs_ctxs[i])) {
+ kfree(kbuf);
+ mutex_unlock(&damon_dbgfs_lock);
+ return -EINVAL;
+ }
+ }
+ ret = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs, true);
+ } else if (!strncmp(kbuf, "off", count)) {
+ ret = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs);
+ } else {
+ ret = -EINVAL;
+ }
+ mutex_unlock(&damon_dbgfs_lock);
+
+ if (!ret)
+ ret = count;
+ 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(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 = -ENOMEM;
+
+ mutex_lock(&damon_dbgfs_lock);
+ dbgfs_ctxs = kmalloc(sizeof(*dbgfs_ctxs), GFP_KERNEL);
+ if (!dbgfs_ctxs)
+ goto out;
+ dbgfs_ctxs[0] = dbgfs_new_ctx();
+ if (!dbgfs_ctxs[0]) {
+ kfree(dbgfs_ctxs);
+ goto out;
+ }
+ 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__);
+ }
+
+out:
+ mutex_unlock(&damon_dbgfs_lock);
+ return rc;
+}
+
+module_init(damon_dbgfs_init);
+
+#include "dbgfs-test.h"