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