arch/powerpc/platforms/powernv/opal-elog.c - linux - Git at Google

 // 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("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;
 }
	// 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("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;
	}