mm/damon/sysfs: support the physical address space monitoring

This commit makes DAMON sysfs interface supports the physical address
space monitoring.  Specifically, this commit adds support of the initial
monitoring regions set feature by adding 'regions' directory under each
target directory and makes context operations file to receive 'paddr' in
addition to 'vaddr'.

As a result, the files hierarchy becomes as below:

    /sys/kernel/mm/damon/admin
    │ kdamonds/nr_kdamonds
    │ │ 0/state,pid
    │ │ │ contexts/nr_contexts
    │ │ │ │ 0/operations
    │ │ │ │ │ monitoring_attrs/
    │ │ │ │ │ │ intervals/sample_us,aggr_us,update_us
    │ │ │ │ │ │ nr_regions/min,max
    │ │ │ │ │ targets/nr_targets
    │ │ │ │ │ │ 0/pid_target
    │ │ │ │ │ │ │ regions/nr_regions    <- NEW DIRECTORY
    │ │ │ │ │ │ │ │ 0/start,end
    │ │ │ │ │ │ │ │ ...
    │ │ │ │ │ │ ...
    │ │ │ │ ...
    │ │ ...

Link: https://lkml.kernel.org/r/20220228081314.5770-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Xin Hao <xhao@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: sjp38

mm/damon/sysfs.c

@@ -113,12 +113,220 @@ static struct kobj_type damon_sysfs_ul_range_ktype = {
 	.default_groups = damon_sysfs_ul_range_groups,
 };
 
+/*
+ * init region directory
+ */
+
+struct damon_sysfs_region {
+	struct kobject kobj;
+	unsigned long start;
+	unsigned long end;
+};
+
+static struct damon_sysfs_region *damon_sysfs_region_alloc(
+		unsigned long start,
+		unsigned long end)
+{
+	struct damon_sysfs_region *region = kmalloc(sizeof(*region),
+			GFP_KERNEL);
+
+	if (!region)
+		return NULL;
+	region->kobj = (struct kobject){};
+	region->start = start;
+	region->end = end;
+	return region;
+}
+
+static ssize_t start_show(struct kobject *kobj, struct kobj_attribute *attr,
+		char *buf)
+{
+	struct damon_sysfs_region *region = container_of(kobj,
+			struct damon_sysfs_region, kobj);
+
+	return sysfs_emit(buf, "%lu\n", region->start);
+}
+
+static ssize_t start_store(struct kobject *kobj, struct kobj_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct damon_sysfs_region *region = container_of(kobj,
+			struct damon_sysfs_region, kobj);
+	int err = kstrtoul(buf, 0, &region->start);
+
+	if (err)
+		return -EINVAL;
+	return count;
+}
+
+static ssize_t end_show(struct kobject *kobj, struct kobj_attribute *attr,
+		char *buf)
+{
+	struct damon_sysfs_region *region = container_of(kobj,
+			struct damon_sysfs_region, kobj);
+
+	return sysfs_emit(buf, "%lu\n", region->end);
+}
+
+static ssize_t end_store(struct kobject *kobj, struct kobj_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct damon_sysfs_region *region = container_of(kobj,
+			struct damon_sysfs_region, kobj);
+	int err = kstrtoul(buf, 0, &region->end);
+
+	if (err)
+		return -EINVAL;
+	return count;
+}
+
+static void damon_sysfs_region_release(struct kobject *kobj)
+{
+	kfree(container_of(kobj, struct damon_sysfs_region, kobj));
+}
+
+static struct kobj_attribute damon_sysfs_region_start_attr =
+		__ATTR_RW_MODE(start, 0600);
+
+static struct kobj_attribute damon_sysfs_region_end_attr =
+		__ATTR_RW_MODE(end, 0600);
+
+static struct attribute *damon_sysfs_region_attrs[] = {
+	&damon_sysfs_region_start_attr.attr,
+	&damon_sysfs_region_end_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_region);
+
+static struct kobj_type damon_sysfs_region_ktype = {
+	.release = damon_sysfs_region_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_region_groups,
+};
+
+/*
+ * init_regions directory
+ */
+
+struct damon_sysfs_regions {
+	struct kobject kobj;
+	struct damon_sysfs_region **regions_arr;
+	int nr;
+};
+
+static struct damon_sysfs_regions *damon_sysfs_regions_alloc(void)
+{
+	return kzalloc(sizeof(struct damon_sysfs_regions), GFP_KERNEL);
+}
+
+static void damon_sysfs_regions_rm_dirs(struct damon_sysfs_regions *regions)
+{
+	struct damon_sysfs_region **regions_arr = regions->regions_arr;
+	int i;
+
+	for (i = 0; i < regions->nr; i++)
+		kobject_put(&regions_arr[i]->kobj);
+	regions->nr = 0;
+	kfree(regions_arr);
+	regions->regions_arr = NULL;
+}
+
+static int damon_sysfs_regions_add_dirs(struct damon_sysfs_regions *regions,
+		int nr_regions)
+{
+	struct damon_sysfs_region **regions_arr, *region;
+	int err, i;
+
+	damon_sysfs_regions_rm_dirs(regions);
+	if (!nr_regions)
+		return 0;
+
+	regions_arr = kmalloc_array(nr_regions, sizeof(*regions_arr),
+			GFP_KERNEL | __GFP_NOWARN);
+	if (!regions_arr)
+		return -ENOMEM;
+	regions->regions_arr = regions_arr;
+
+	for (i = 0; i < nr_regions; i++) {
+		region = damon_sysfs_region_alloc(0, 0);
+		if (!region) {
+			damon_sysfs_regions_rm_dirs(regions);
+			return -ENOMEM;
+		}
+
+		err = kobject_init_and_add(&region->kobj,
+				&damon_sysfs_region_ktype, &regions->kobj,
+				"%d", i);
+		if (err) {
+			kobject_put(&region->kobj);
+			damon_sysfs_regions_rm_dirs(regions);
+			return err;
+		}
+
+		regions_arr[i] = region;
+		regions->nr++;
+	}
+	return 0;
+}
+
+static ssize_t nr_regions_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_regions *regions = container_of(kobj,
+			struct damon_sysfs_regions, kobj);
+
+	return sysfs_emit(buf, "%d\n", regions->nr);
+}
+
+static ssize_t nr_regions_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_regions *regions = container_of(kobj,
+			struct damon_sysfs_regions, kobj);
+	int nr, err = kstrtoint(buf, 0, &nr);
+
+	if (err)
+		return err;
+	if (nr < 0)
+		return -EINVAL;
+
+	if (!mutex_trylock(&damon_sysfs_lock))
+		return -EBUSY;
+	err = damon_sysfs_regions_add_dirs(regions, nr);
+	mutex_unlock(&damon_sysfs_lock);
+	if (err)
+		return err;
+
+	return count;
+}
+
+static void damon_sysfs_regions_release(struct kobject *kobj)
+{
+	kfree(container_of(kobj, struct damon_sysfs_regions, kobj));
+}
+
+static struct kobj_attribute damon_sysfs_regions_nr_attr =
+		__ATTR_RW_MODE(nr_regions, 0600);
+
+static struct attribute *damon_sysfs_regions_attrs[] = {
+	&damon_sysfs_regions_nr_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_regions);
+
+static struct kobj_type damon_sysfs_regions_ktype = {
+	.release = damon_sysfs_regions_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_regions_groups,
+};
+
 /*
  * target directory
  */
 
 struct damon_sysfs_target {
 	struct kobject kobj;
+	struct damon_sysfs_regions *regions;
 	int pid;
 };
 
@@ -127,6 +335,29 @@ static struct damon_sysfs_target *damon_sysfs_target_alloc(void)
 	return kzalloc(sizeof(struct damon_sysfs_target), GFP_KERNEL);
 }
 
+static int damon_sysfs_target_add_dirs(struct damon_sysfs_target *target)
+{
+	struct damon_sysfs_regions *regions = damon_sysfs_regions_alloc();
+	int err;
+
+	if (!regions)
+		return -ENOMEM;
+
+	err = kobject_init_and_add(&regions->kobj, &damon_sysfs_regions_ktype,
+			&target->kobj, "regions");
+	if (err)
+		kobject_put(&regions->kobj);
+	else
+		target->regions = regions;
+	return err;
+}
+
+static void damon_sysfs_target_rm_dirs(struct damon_sysfs_target *target)
+{
+	damon_sysfs_regions_rm_dirs(target->regions);
+	kobject_put(&target->regions->kobj);
+}
+
 static ssize_t pid_target_show(struct kobject *kobj,
 		struct kobj_attribute *attr, char *buf)
 {
@@ -188,8 +419,10 @@ static void damon_sysfs_targets_rm_dirs(struct damon_sysfs_targets *targets)
 	struct damon_sysfs_target **targets_arr = targets->targets_arr;
 	int i;
 
-	for (i = 0; i < targets->nr; i++)
+	for (i = 0; i < targets->nr; i++) {
+		damon_sysfs_target_rm_dirs(targets_arr[i]);
 		kobject_put(&targets_arr[i]->kobj);
+	}
 	targets->nr = 0;
 	kfree(targets_arr);
 	targets->targets_arr = NULL;
@@ -224,6 +457,10 @@ static int damon_sysfs_targets_add_dirs(struct damon_sysfs_targets *targets,
 		if (err)
 			goto out;
 
+		err = damon_sysfs_target_add_dirs(target);
+		if (err)
+			goto out;
+
 		targets_arr[i] = target;
 		targets->nr++;
 	}
@@ -610,9 +847,6 @@ static ssize_t operations_store(struct kobject *kobj,
 
 	for (id = 0; id < NR_DAMON_OPS; id++) {
 		if (sysfs_streq(buf, damon_sysfs_ops_strs[id])) {
-			/* Support only vaddr */
-			if (id != DAMON_OPS_VADDR)
-				return -EINVAL;
 			context->ops_id = id;
 			return count;
 		}
@@ -857,10 +1091,37 @@ static void damon_sysfs_destroy_targets(struct damon_ctx *ctx)
 	}
 }
 
+static int damon_sysfs_set_regions(struct damon_target *t,
+		struct damon_sysfs_regions *sysfs_regions)
+{
+	int i;
+
+	for (i = 0; i < sysfs_regions->nr; i++) {
+		struct damon_sysfs_region *sys_region =
+			sysfs_regions->regions_arr[i];
+		struct damon_region *prev, *r;
+
+		if (sys_region->start > sys_region->end)
+			return -EINVAL;
+		r = damon_new_region(sys_region->start, sys_region->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;
+			}
+		}
+	}
+	return 0;
+}
+
 static int damon_sysfs_set_targets(struct damon_ctx *ctx,
 		struct damon_sysfs_targets *sysfs_targets)
 {
-	int i;
+	int i, err;
 
 	for (i = 0; i < sysfs_targets->nr; i++) {
 		struct damon_sysfs_target *sys_target =
@@ -879,6 +1140,11 @@ static int damon_sysfs_set_targets(struct damon_ctx *ctx,
 			}
 		}
 		damon_add_target(ctx, t);
+		err = damon_sysfs_set_regions(t, sys_target->regions);
+		if (err) {
+			damon_sysfs_destroy_targets(ctx);
+			return err;
+		}
 	}
 	return 0;
 }