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