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Diffstat (limited to '')
-rw-r--r-- | arch/powerpc/platforms/powernv/opal-elog.c | 340 |
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; +} |