1 files changed, 340 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/opal-elog.c b/arch/powerpc/platforms/powernv/opal-elog.c
new file mode 100644
index 000000000..554fdd7f8
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/opal-elog.c
@@ -0,0 +1,340 @@
+// 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,
+};
+ATTRIBUTE_GROUPS(elog_default);
+
+static struct kobj_type elog_ktype = {
+	.sysfs_ops = &elog_sysfs_ops,
+	.release = &elog_release,
+	.default_groups = elog_default_groups,
+};
+
+/* 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;
+}