[mirror_ubuntu-jammy-kernel.git] / arch / powerpc / platforms / powernv / opal-elog.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Error log support on PowerNV.
 *
 * Copyright 2013,2014 IBM Corp.
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/fs.h>
#include <linux/vmalloc.h>
#include <linux/fcntl.h>
#include <linux/kobject.h>
#include <linux/uaccess.h>
#include <asm/opal.h>

struct elog_obj {
	struct kobject kobj;
	struct bin_attribute raw_attr;
	uint64_t id;
	uint64_t type;
	size_t size;
	char *buffer;
};
#define to_elog_obj(x) container_of(x, struct elog_obj, kobj)

struct elog_attribute {
	struct attribute attr;
	ssize_t (*show)(struct elog_obj *elog, struct elog_attribute *attr,
			char *buf);
	ssize_t (*store)(struct elog_obj *elog, struct elog_attribute *attr,
			 const char *buf, size_t count);
};
#define to_elog_attr(x) container_of(x, struct elog_attribute, attr)

static ssize_t elog_id_show(struct elog_obj *elog_obj,
			    struct elog_attribute *attr,
			    char *buf)
{
	return sprintf(buf, "0x%llx\n", elog_obj->id);
}

static const char *elog_type_to_string(uint64_t type)
{
	switch (type) {
	case 0: return "PEL";
	default: return "unknown";
	}
}

static ssize_t elog_type_show(struct elog_obj *elog_obj,
			      struct elog_attribute *attr,
			      char *buf)
{
	return sprintf(buf, "0x%llx %s\n",
		       elog_obj->type,
		       elog_type_to_string(elog_obj->type));
}

static ssize_t elog_ack_show(struct elog_obj *elog_obj,
			     struct elog_attribute *attr,
			     char *buf)
{
	return sprintf(buf, "ack - acknowledge log message\n");
}

static ssize_t elog_ack_store(struct elog_obj *elog_obj,
			      struct elog_attribute *attr,
			      const char *buf,
			      size_t count)
{
	/*
	 * Try to self remove this attribute. If we are successful,
	 * delete the kobject itself.
	 */
	if (sysfs_remove_file_self(&elog_obj->kobj, &attr->attr)) {
		opal_send_ack_elog(elog_obj->id);
		kobject_put(&elog_obj->kobj);
	}
	return count;
}

static struct elog_attribute id_attribute =
	__ATTR(id, 0444, elog_id_show, NULL);
static struct elog_attribute type_attribute =
	__ATTR(type, 0444, elog_type_show, NULL);
static struct elog_attribute ack_attribute =
	__ATTR(acknowledge, 0660, elog_ack_show, elog_ack_store);

static struct kset *elog_kset;

static ssize_t elog_attr_show(struct kobject *kobj,
			      struct attribute *attr,
			      char *buf)
{
	struct elog_attribute *attribute;
	struct elog_obj *elog;

	attribute = to_elog_attr(attr);
	elog = to_elog_obj(kobj);

	if (!attribute->show)
		return -EIO;

	return attribute->show(elog, attribute, buf);
}

static ssize_t elog_attr_store(struct kobject *kobj,
			       struct attribute *attr,
			       const char *buf, size_t len)
{
	struct elog_attribute *attribute;
	struct elog_obj *elog;

	attribute = to_elog_attr(attr);
	elog = to_elog_obj(kobj);

	if (!attribute->store)
		return -EIO;

	return attribute->store(elog, attribute, buf, len);
}

static const struct sysfs_ops elog_sysfs_ops = {
	.show = elog_attr_show,
	.store = elog_attr_store,
};

static void elog_release(struct kobject *kobj)
{
	struct elog_obj *elog;

	elog = to_elog_obj(kobj);
	kfree(elog->buffer);
	kfree(elog);
}

static struct attribute *elog_default_attrs[] = {
	&id_attribute.attr,
	&type_attribute.attr,
	&ack_attribute.attr,
	NULL,
};

static struct kobj_type elog_ktype = {
	.sysfs_ops = &elog_sysfs_ops,
	.release = &elog_release,
	.default_attrs = elog_default_attrs,
};

/* Maximum size of a single log on FSP is 16KB */
#define OPAL_MAX_ERRLOG_SIZE	16384

static ssize_t raw_attr_read(struct file *filep, struct kobject *kobj,
			     struct bin_attribute *bin_attr,
			     char *buffer, loff_t pos, size_t count)
{
	int opal_rc;

	struct elog_obj *elog = to_elog_obj(kobj);

	/* We may have had an error reading before, so let's retry */
	if (!elog->buffer) {
		elog->buffer = kzalloc(elog->size, GFP_KERNEL);
		if (!elog->buffer)
			return -EIO;

		opal_rc = opal_read_elog(__pa(elog->buffer),
					 elog->size, elog->id);
		if (opal_rc != OPAL_SUCCESS) {
			pr_err_ratelimited("ELOG: log read failed for log-id=%llx\n",
					   elog->id);
			kfree(elog->buffer);
			elog->buffer = NULL;
			return -EIO;
		}
	}

	memcpy(buffer, elog->buffer + pos, count);

	return count;
}

static void create_elog_obj(uint64_t id, size_t size, uint64_t type)
{
	struct elog_obj *elog;
	int rc;

	elog = kzalloc(sizeof(*elog), GFP_KERNEL);
	if (!elog)
		return;

	elog->kobj.kset = elog_kset;

	kobject_init(&elog->kobj, &elog_ktype);

	sysfs_bin_attr_init(&elog->raw_attr);

	elog->raw_attr.attr.name = "raw";
	elog->raw_attr.attr.mode = 0400;
	elog->raw_attr.size = size;
	elog->raw_attr.read = raw_attr_read;

	elog->id = id;
	elog->size = size;
	elog->type = type;

	elog->buffer = kzalloc(elog->size, GFP_KERNEL);

	if (elog->buffer) {
		rc = opal_read_elog(__pa(elog->buffer),
					 elog->size, elog->id);
		if (rc != OPAL_SUCCESS) {
			pr_err("ELOG: log read failed for log-id=%llx\n",
			       elog->id);
			kfree(elog->buffer);
			elog->buffer = NULL;
		}
	}

	rc = kobject_add(&elog->kobj, NULL, "0x%llx", id);
	if (rc) {
		kobject_put(&elog->kobj);
		return;
	}

	/*
	 * As soon as the sysfs file for this elog is created/activated there is
	 * a chance the opal_errd daemon (or any userspace) might read and
	 * acknowledge the elog before kobject_uevent() is called. If that
	 * happens then there is a potential race between
	 * elog_ack_store->kobject_put() and kobject_uevent() which leads to a
	 * use-after-free of a kernfs object resulting in a kernel crash.
	 *
	 * To avoid that, we need to take a reference on behalf of the bin file,
	 * so that our reference remains valid while we call kobject_uevent().
	 * We then drop our reference before exiting the function, leaving the
	 * bin file to drop the last reference (if it hasn't already).
	 */

	/* Take a reference for the bin file */
	kobject_get(&elog->kobj);
	rc = sysfs_create_bin_file(&elog->kobj, &elog->raw_attr);
	if (rc == 0) {
		kobject_uevent(&elog->kobj, KOBJ_ADD);
	} else {
		/* Drop the reference taken for the bin file */
		kobject_put(&elog->kobj);
	}

	/* Drop our reference */
	kobject_put(&elog->kobj);

	return;
}

static irqreturn_t elog_event(int irq, void *data)
{
	__be64 size;
	__be64 id;
	__be64 type;
	uint64_t elog_size;
	uint64_t log_id;
	uint64_t elog_type;
	int rc;
	char name[2+16+1];
	struct kobject *kobj;

	rc = opal_get_elog_size(&id, &size, &type);
	if (rc != OPAL_SUCCESS) {
		pr_err("ELOG: OPAL log info read failed\n");
		return IRQ_HANDLED;
	}

	elog_size = be64_to_cpu(size);
	log_id = be64_to_cpu(id);
	elog_type = be64_to_cpu(type);

	WARN_ON(elog_size > OPAL_MAX_ERRLOG_SIZE);

	if (elog_size >= OPAL_MAX_ERRLOG_SIZE)
		elog_size  =  OPAL_MAX_ERRLOG_SIZE;

	sprintf(name, "0x%llx", log_id);

	/* we may get notified twice, let's handle
	 * that gracefully and not create two conflicting
	 * entries.
	 */
	kobj = kset_find_obj(elog_kset, name);
	if (kobj) {
		/* Drop reference added by kset_find_obj() */
		kobject_put(kobj);
		return IRQ_HANDLED;
	}

	create_elog_obj(log_id, elog_size, elog_type);

	return IRQ_HANDLED;
}

int __init opal_elog_init(void)
{
	int rc = 0, irq;

	/* ELOG not supported by firmware */
	if (!opal_check_token(OPAL_ELOG_READ))
		return -1;

	elog_kset = kset_create_and_add("elog", NULL, opal_kobj);
	if (!elog_kset) {
		pr_warn("%s: failed to create elog kset\n", __func__);
		return -1;
	}

	irq = opal_event_request(ilog2(OPAL_EVENT_ERROR_LOG_AVAIL));
	if (!irq) {
		pr_err("%s: Can't register OPAL event irq (%d)\n",
		       __func__, irq);
		return irq;
	}

	rc = request_threaded_irq(irq, NULL, elog_event,
			IRQF_TRIGGER_HIGH | IRQF_ONESHOT, "opal-elog", NULL);
	if (rc) {
		pr_err("%s: Can't request OPAL event irq (%d)\n",
		       __func__, rc);
		return rc;
	}

	/* We are now ready to pull error logs from opal. */
	if (opal_check_token(OPAL_ELOG_RESEND))
		opal_resend_pending_logs();

	return 0;
}
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
774fea1a SS	2	/*
	3	* Error log support on PowerNV.
	4	*
	5	* Copyright 2013,2014 IBM Corp.
774fea1a SS	6	*/
	7	#include <linux/kernel.h>
	8	#include <linux/init.h>
74159a70	9	#include <linux/interrupt.h>
774fea1a SS	10	#include <linux/of.h>
	11	#include <linux/slab.h>
	12	#include <linux/sysfs.h>
	13	#include <linux/fs.h>
	14	#include <linux/vmalloc.h>
	15	#include <linux/fcntl.h>
	16	#include <linux/kobject.h>
7c0f6ba6	17	#include <linux/uaccess.h>
774fea1a SS	18	#include <asm/opal.h>
	19
	20	struct elog_obj {
	21	struct kobject kobj;
	22	struct bin_attribute raw_attr;
	23	uint64_t id;
	24	uint64_t type;
	25	size_t size;
	26	char *buffer;
	27	};
	28	#define to_elog_obj(x) container_of(x, struct elog_obj, kobj)
	29
	30	struct elog_attribute {
	31	struct attribute attr;
	32	ssize_t (show)(struct elog_obj elog, struct elog_attribute *attr,
	33	char *buf);
	34	ssize_t (store)(struct elog_obj elog, struct elog_attribute *attr,
	35	const char *buf, size_t count);
	36	};
	37	#define to_elog_attr(x) container_of(x, struct elog_attribute, attr)
	38
	39	static ssize_t elog_id_show(struct elog_obj *elog_obj,
	40	struct elog_attribute *attr,
	41	char *buf)
	42	{
	43	return sprintf(buf, "0x%llx\n", elog_obj->id);
	44	}
	45
	46	static const char *elog_type_to_string(uint64_t type)
	47	{
	48	switch (type) {
	49	case 0: return "PEL";
	50	default: return "unknown";
	51	}
	52	}
	53
	54	static ssize_t elog_type_show(struct elog_obj *elog_obj,
	55	struct elog_attribute *attr,
	56	char *buf)
	57	{
	58	return sprintf(buf, "0x%llx %s\n",
	59	elog_obj->type,
	60	elog_type_to_string(elog_obj->type));
	61	}
	62
	63	static ssize_t elog_ack_show(struct elog_obj *elog_obj,
	64	struct elog_attribute *attr,
	65	char *buf)
	66	{
	67	return sprintf(buf, "ack - acknowledge log message\n");
	68	}
	69
774fea1a SS	70	static ssize_t elog_ack_store(struct elog_obj *elog_obj,
	71	struct elog_attribute *attr,
	72	const char *buf,
	73	size_t count)
	74	{
d4263b12 AK	75	/*
	76	* Try to self remove this attribute. If we are successful,
	77	* delete the kobject itself.
	78	*/
	79	if (sysfs_remove_file_self(&elog_obj->kobj, &attr->attr)) {
	80	opal_send_ack_elog(elog_obj->id);
	81	kobject_put(&elog_obj->kobj);
	82	}
774fea1a SS	83	return count;
	84	}
	85
	86	static struct elog_attribute id_attribute =
57ad583f	87	__ATTR(id, 0444, elog_id_show, NULL);
774fea1a	88	static struct elog_attribute type_attribute =
57ad583f	89	__ATTR(type, 0444, elog_type_show, NULL);
774fea1a SS	90	static struct elog_attribute ack_attribute =
	91	__ATTR(acknowledge, 0660, elog_ack_show, elog_ack_store);
	92
	93	static struct kset *elog_kset;
	94
	95	static ssize_t elog_attr_show(struct kobject *kobj,
	96	struct attribute *attr,
	97	char *buf)
	98	{
	99	struct elog_attribute *attribute;
	100	struct elog_obj *elog;
	101
	102	attribute = to_elog_attr(attr);
	103	elog = to_elog_obj(kobj);
	104
	105	if (!attribute->show)
	106	return -EIO;
	107
	108	return attribute->show(elog, attribute, buf);
	109	}
	110
	111	static ssize_t elog_attr_store(struct kobject *kobj,
	112	struct attribute *attr,
	113	const char *buf, size_t len)
	114	{
	115	struct elog_attribute *attribute;
	116	struct elog_obj *elog;
	117
	118	attribute = to_elog_attr(attr);
	119	elog = to_elog_obj(kobj);
	120
	121	if (!attribute->store)
	122	return -EIO;
	123
	124	return attribute->store(elog, attribute, buf, len);
	125	}
	126
	127	static const struct sysfs_ops elog_sysfs_ops = {
	128	.show = elog_attr_show,
	129	.store = elog_attr_store,
	130	};
	131
	132	static void elog_release(struct kobject *kobj)
	133	{
	134	struct elog_obj *elog;
	135
	136	elog = to_elog_obj(kobj);
	137	kfree(elog->buffer);
	138	kfree(elog);
	139	}
	140
	141	static struct attribute *elog_default_attrs[] = {
	142	&id_attribute.attr,
	143	&type_attribute.attr,
	144	&ack_attribute.attr,
	145	NULL,
	146	};
	147
	148	static struct kobj_type elog_ktype = {
	149	.sysfs_ops = &elog_sysfs_ops,
	150	.release = &elog_release,
	151	.default_attrs = elog_default_attrs,
	152	};
	153
154	/* Maximum size of a single log on FSP is 16KB */
155	#define OPAL_MAX_ERRLOG_SIZE 16384
156
157	static ssize_t raw_attr_read(struct file filep, struct kobject kobj,
158	struct bin_attribute *bin_attr,
159	char *buffer, loff_t pos, size_t count)
160	{
161	int opal_rc;
162
163	struct elog_obj *elog = to_elog_obj(kobj);
164
165	/* We may have had an error reading before, so let's retry */
166	if (!elog->buffer) {
167	elog->buffer = kzalloc(elog->size, GFP_KERNEL);
168	if (!elog->buffer)
169	return -EIO;
170
171	opal_rc = opal_read_elog(__pa(elog->buffer),
172	elog->size, elog->id);
173	if (opal_rc != OPAL_SUCCESS) {
c88017cf AD	174	pr_err_ratelimited("ELOG: log read failed for log-id=%llx\n",
c88017cf AD	175	elog->id);
774fea1a SS	176	kfree(elog->buffer);
	177	elog->buffer = NULL;
	178	return -EIO;
	179	}
	180	}
	181
	182	memcpy(buffer, elog->buffer + pos, count);
	183
	184	return count;
	185	}
	186
aea948bb	187	static void create_elog_obj(uint64_t id, size_t size, uint64_t type)
774fea1a SS	188	{
	189	struct elog_obj *elog;
	190	int rc;
	191
	192	elog = kzalloc(sizeof(*elog), GFP_KERNEL);
	193	if (!elog)
aea948bb	194	return;
774fea1a SS	195
	196	elog->kobj.kset = elog_kset;
	197
	198	kobject_init(&elog->kobj, &elog_ktype);
	199
	200	sysfs_bin_attr_init(&elog->raw_attr);
	201
	202	elog->raw_attr.attr.name = "raw";
	203	elog->raw_attr.attr.mode = 0400;
	204	elog->raw_attr.size = size;
	205	elog->raw_attr.read = raw_attr_read;
	206
	207	elog->id = id;
	208	elog->size = size;
	209	elog->type = type;
	210
	211	elog->buffer = kzalloc(elog->size, GFP_KERNEL);
	212
	213	if (elog->buffer) {
	214	rc = opal_read_elog(__pa(elog->buffer),
	215	elog->size, elog->id);
	216	if (rc != OPAL_SUCCESS) {
	217	pr_err("ELOG: log read failed for log-id=%llx\n",
	218	elog->id);
	219	kfree(elog->buffer);
	220	elog->buffer = NULL;
	221	}
	222	}
	223
	224	rc = kobject_add(&elog->kobj, NULL, "0x%llx", id);
	225	if (rc) {
	226	kobject_put(&elog->kobj);
aea948bb	227	return;
774fea1a SS	228	}
774fea1a SS	229
aea948bb MS	230	/*
	231	* As soon as the sysfs file for this elog is created/activated there is
	232	* a chance the opal_errd daemon (or any userspace) might read and
	233	* acknowledge the elog before kobject_uevent() is called. If that
	234	* happens then there is a potential race between
	235	* elog_ack_store->kobject_put() and kobject_uevent() which leads to a
	236	* use-after-free of a kernfs object resulting in a kernel crash.
	237	*
	238	* To avoid that, we need to take a reference on behalf of the bin file,
	239	* so that our reference remains valid while we call kobject_uevent().
	240	* We then drop our reference before exiting the function, leaving the
	241	* bin file to drop the last reference (if it hasn't already).
	242	*/
	243
	244	/* Take a reference for the bin file */
	245	kobject_get(&elog->kobj);
774fea1a	246	rc = sysfs_create_bin_file(&elog->kobj, &elog->raw_attr);
aea948bb MS	247	if (rc == 0) {
	248	kobject_uevent(&elog->kobj, KOBJ_ADD);
	249	} else {
	250	/* Drop the reference taken for the bin file */
774fea1a	251	kobject_put(&elog->kobj);
774fea1a SS	252	}
774fea1a SS	253
aea948bb MS	254	/* Drop our reference */
aea948bb MS	255	kobject_put(&elog->kobj);
774fea1a	256
aea948bb	257	return;
774fea1a SS	258	}
774fea1a SS	259
a8956a7b	260	static irqreturn_t elog_event(int irq, void *data)
774fea1a	261	{
14ad0c58 AB	262	__be64 size;
	263	__be64 id;
	264	__be64 type;
2bad7423	265	uint64_t elog_size;
774fea1a SS	266	uint64_t log_id;
	267	uint64_t elog_type;
	268	int rc;
	269	char name[2+16+1];
a9cbf0b2	270	struct kobject *kobj;
774fea1a	271
14ad0c58	272	rc = opal_get_elog_size(&id, &size, &type);
774fea1a	273	if (rc != OPAL_SUCCESS) {
fa952c54	274	pr_err("ELOG: OPAL log info read failed\n");
a8956a7b	275	return IRQ_HANDLED;
774fea1a SS	276	}
774fea1a SS	277
14ad0c58 AB	278	elog_size = be64_to_cpu(size);
	279	log_id = be64_to_cpu(id);
	280	elog_type = be64_to_cpu(type);
	281
fa952c54	282	WARN_ON(elog_size > OPAL_MAX_ERRLOG_SIZE);
774fea1a SS	283
	284	if (elog_size >= OPAL_MAX_ERRLOG_SIZE)
	285	elog_size = OPAL_MAX_ERRLOG_SIZE;
	286
	287	sprintf(name, "0x%llx", log_id);
	288
	289	/* we may get notified twice, let's handle
	290	* that gracefully and not create two conflicting
	291	* entries.
	292	*/
a9cbf0b2 MO	293	kobj = kset_find_obj(elog_kset, name);
	294	if (kobj) {
	295	/* Drop reference added by kset_find_obj() */
	296	kobject_put(kobj);
a8956a7b	297	return IRQ_HANDLED;
a9cbf0b2	298	}
774fea1a SS	299
774fea1a SS	300	create_elog_obj(log_id, elog_size, elog_type);
774fea1a	301
74159a70	302	return IRQ_HANDLED;
774fea1a SS	303	}
774fea1a SS	304
774fea1a SS	305	int __init opal_elog_init(void)
774fea1a SS	306	{
74159a70	307	int rc = 0, irq;
774fea1a	308
7dc992ec MN	309	/* ELOG not supported by firmware */
	310	if (!opal_check_token(OPAL_ELOG_READ))
	311	return -1;
	312
774fea1a SS	313	elog_kset = kset_create_and_add("elog", NULL, opal_kobj);
	314	if (!elog_kset) {
	315	pr_warn("%s: failed to create elog kset\n", __func__);
	316	return -1;
	317	}
	318
74159a70 AP	319	irq = opal_event_request(ilog2(OPAL_EVENT_ERROR_LOG_AVAIL));
	320	if (!irq) {
	321	pr_err("%s: Can't register OPAL event irq (%d)\n",
	322	__func__, irq);
	323	return irq;
	324	}
	325
a8956a7b AP	326	rc = request_threaded_irq(irq, NULL, elog_event,
a8956a7b AP	327	IRQF_TRIGGER_HIGH \| IRQF_ONESHOT, "opal-elog", NULL);
774fea1a	328	if (rc) {
74159a70 AP	329	pr_err("%s: Can't request OPAL event irq (%d)\n",
74159a70 AP	330	__func__, rc);
774fea1a SS	331	return rc;
	332	}
	333
	334	/* We are now ready to pull error logs from opal. */
fc81de63 SS	335	if (opal_check_token(OPAL_ELOG_RESEND))
fc81de63 SS	336	opal_resend_pending_logs();
774fea1a SS	337
	338	return 0;
	339	}