arch/powerpc/platforms/powernv/opal-dump.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * PowerNV OPAL Dump Interface
   4  *
   5  * Copyright 2013,2014 IBM Corp.
   6  */
   7
   8 #include <linux/kobject.h>
   9 #include <linux/mm.h>
  10 #include <linux/slab.h>
  11 #include <linux/vmalloc.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/delay.h>
  14 #include <linux/interrupt.h>
  15
  16 #include <asm/opal.h>
  17
  18 #define DUMP_TYPE_FSP   0x01
  19
  20 struct dump_obj {
  21         struct kobject  kobj;
  22         struct bin_attribute dump_attr;
  23         uint32_t        id;  /* becomes object name */
  24         uint32_t        type;
  25         uint32_t        size;
  26         char            *buffer;
  27 };
  28 #define to_dump_obj(x) container_of(x, struct dump_obj, kobj)
  29
  30 struct dump_attribute {
  31         struct attribute attr;
  32         ssize_t (*show)(struct dump_obj *dump, struct dump_attribute *attr,
  33                         char *buf);
  34         ssize_t (*store)(struct dump_obj *dump, struct dump_attribute *attr,
  35                          const char *buf, size_t count);
  36 };
  37 #define to_dump_attr(x) container_of(x, struct dump_attribute, attr)
  38
  39 static ssize_t dump_id_show(struct dump_obj *dump_obj,
  40                             struct dump_attribute *attr,
  41                             char *buf)
  42 {
  43         return sprintf(buf, "0x%x\n", dump_obj->id);
  44 }
  45
  46 static const char* dump_type_to_string(uint32_t type)
  47 {
  48         switch (type) {
  49         case 0x01: return "SP Dump";
  50         case 0x02: return "System/Platform Dump";
  51         case 0x03: return "SMA Dump";
  52         default: return "unknown";
  53         }
  54 }
  55
  56 static ssize_t dump_type_show(struct dump_obj *dump_obj,
  57                               struct dump_attribute *attr,
  58                               char *buf)
  59 {
  60
  61         return sprintf(buf, "0x%x %s\n", dump_obj->type,
  62                        dump_type_to_string(dump_obj->type));
  63 }
  64
  65 static ssize_t dump_ack_show(struct dump_obj *dump_obj,
  66                              struct dump_attribute *attr,
  67                              char *buf)
  68 {
  69         return sprintf(buf, "ack - acknowledge dump\n");
  70 }
  71
  72 /*
  73  * Send acknowledgement to OPAL
  74  */
  75 static int64_t dump_send_ack(uint32_t dump_id)
  76 {
  77         int rc;
  78
  79         rc = opal_dump_ack(dump_id);
  80         if (rc)
  81                 pr_warn("%s: Failed to send ack to Dump ID 0x%x (%d)\n",
  82                         __func__, dump_id, rc);
  83         return rc;
  84 }
  85
  86 static ssize_t dump_ack_store(struct dump_obj *dump_obj,
  87                               struct dump_attribute *attr,
  88                               const char *buf,
  89                               size_t count)
  90 {
  91         dump_send_ack(dump_obj->id);
  92         sysfs_remove_file_self(&dump_obj->kobj, &attr->attr);
  93         kobject_put(&dump_obj->kobj);
  94         return count;
  95 }
  96
  97 /* Attributes of a dump
  98  * The binary attribute of the dump itself is dynamic
  99  * due to the dynamic size of the dump
 100  */
 101 static struct dump_attribute id_attribute =
 102         __ATTR(id, 0444, dump_id_show, NULL);
 103 static struct dump_attribute type_attribute =
 104         __ATTR(type, 0444, dump_type_show, NULL);
 105 static struct dump_attribute ack_attribute =
 106         __ATTR(acknowledge, 0660, dump_ack_show, dump_ack_store);
 107
 108 static ssize_t init_dump_show(struct dump_obj *dump_obj,
 109                               struct dump_attribute *attr,
 110                               char *buf)
 111 {
 112         return sprintf(buf, "1 - initiate Service Processor(FSP) dump\n");
 113 }
 114
 115 static int64_t dump_fips_init(uint8_t type)
 116 {
 117         int rc;
 118
 119         rc = opal_dump_init(type);
 120         if (rc)
 121                 pr_warn("%s: Failed to initiate FSP dump (%d)\n",
 122                         __func__, rc);
 123         return rc;
 124 }
 125
 126 static ssize_t init_dump_store(struct dump_obj *dump_obj,
 127                                struct dump_attribute *attr,
 128                                const char *buf,
 129                                size_t count)
 130 {
 131         int rc;
 132
 133         rc = dump_fips_init(DUMP_TYPE_FSP);
 134         if (rc == OPAL_SUCCESS)
 135                 pr_info("%s: Initiated FSP dump\n", __func__);
 136
 137         return count;
 138 }
 139
 140 static struct dump_attribute initiate_attribute =
 141         __ATTR(initiate_dump, 0600, init_dump_show, init_dump_store);
 142
 143 static struct attribute *initiate_attrs[] = {
 144         &initiate_attribute.attr,
 145         NULL,
 146 };
 147
 148 static struct attribute_group initiate_attr_group = {
 149         .attrs = initiate_attrs,
 150 };
 151
 152 static struct kset *dump_kset;
 153
 154 static ssize_t dump_attr_show(struct kobject *kobj,
 155                               struct attribute *attr,
 156                               char *buf)
 157 {
 158         struct dump_attribute *attribute;
 159         struct dump_obj *dump;
 160
 161         attribute = to_dump_attr(attr);
 162         dump = to_dump_obj(kobj);
 163
 164         if (!attribute->show)
 165                 return -EIO;
 166
 167         return attribute->show(dump, attribute, buf);
 168 }
 169
 170 static ssize_t dump_attr_store(struct kobject *kobj,
 171                                struct attribute *attr,
 172                                const char *buf, size_t len)
 173 {
 174         struct dump_attribute *attribute;
 175         struct dump_obj *dump;
 176
 177         attribute = to_dump_attr(attr);
 178         dump = to_dump_obj(kobj);
 179
 180         if (!attribute->store)
 181                 return -EIO;
 182
 183         return attribute->store(dump, attribute, buf, len);
 184 }
 185
 186 static const struct sysfs_ops dump_sysfs_ops = {
 187         .show = dump_attr_show,
 188         .store = dump_attr_store,
 189 };
 190
 191 static void dump_release(struct kobject *kobj)
 192 {
 193         struct dump_obj *dump;
 194
 195         dump = to_dump_obj(kobj);
 196         vfree(dump->buffer);
 197         kfree(dump);
 198 }
 199
 200 static struct attribute *dump_default_attrs[] = {
 201         &id_attribute.attr,
 202         &type_attribute.attr,
 203         &ack_attribute.attr,
 204         NULL,
 205 };
 206
 207 static struct kobj_type dump_ktype = {
 208         .sysfs_ops = &dump_sysfs_ops,
 209         .release = &dump_release,
 210         .default_attrs = dump_default_attrs,
 211 };
 212
 213 static int64_t dump_read_info(uint32_t *dump_id, uint32_t *dump_size, uint32_t *dump_type)
 214 {
 215         __be32 id, size, type;
 216         int rc;
 217
 218         type = cpu_to_be32(0xffffffff);
 219
 220         rc = opal_dump_info2(&id, &size, &type);
 221         if (rc == OPAL_PARAMETER)
 222                 rc = opal_dump_info(&id, &size);
 223
 224         if (rc) {
 225                 pr_warn("%s: Failed to get dump info (%d)\n",
 226                         __func__, rc);
 227                 return rc;
 228         }
 229
 230         *dump_id = be32_to_cpu(id);
 231         *dump_size = be32_to_cpu(size);
 232         *dump_type = be32_to_cpu(type);
 233
 234         return rc;
 235 }
 236
 237 static int64_t dump_read_data(struct dump_obj *dump)
 238 {
 239         struct opal_sg_list *list;
 240         uint64_t addr;
 241         int64_t rc;
 242
 243         /* Allocate memory */
 244         dump->buffer = vzalloc(PAGE_ALIGN(dump->size));
 245         if (!dump->buffer) {
 246                 pr_err("%s : Failed to allocate memory\n", __func__);
 247                 rc = -ENOMEM;
 248                 goto out;
 249         }
 250
 251         /* Generate SG list */
 252         list = opal_vmalloc_to_sg_list(dump->buffer, dump->size);
 253         if (!list) {
 254                 rc = -ENOMEM;
 255                 goto out;
 256         }
 257
 258         /* First entry address */
 259         addr = __pa(list);
 260
 261         /* Fetch data */
 262         rc = OPAL_BUSY_EVENT;
 263         while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
 264                 rc = opal_dump_read(dump->id, addr);
 265                 if (rc == OPAL_BUSY_EVENT) {
 266                         opal_poll_events(NULL);
 267                         msleep(20);
 268                 }
 269         }
 270
 271         if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL)
 272                 pr_warn("%s: Extract dump failed for ID 0x%x\n",
 273                         __func__, dump->id);
 274
 275         /* Free SG list */
 276         opal_free_sg_list(list);
 277
 278 out:
 279         return rc;
 280 }
 281
 282 static ssize_t dump_attr_read(struct file *filep, struct kobject *kobj,
 283                               struct bin_attribute *bin_attr,
 284                               char *buffer, loff_t pos, size_t count)
 285 {
 286         ssize_t rc;
 287
 288         struct dump_obj *dump = to_dump_obj(kobj);
 289
 290         if (!dump->buffer) {
 291                 rc = dump_read_data(dump);
 292
 293                 if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL) {
 294                         vfree(dump->buffer);
 295                         dump->buffer = NULL;
 296
 297                         return -EIO;
 298                 }
 299                 if (rc == OPAL_PARTIAL) {
 300                         /* On a partial read, we just return EIO
 301                          * and rely on userspace to ask us to try
 302                          * again.
 303                          */
 304                         pr_info("%s: Platform dump partially read. ID = 0x%x\n",
 305                                 __func__, dump->id);
 306                         return -EIO;
 307                 }
 308         }
 309
 310         memcpy(buffer, dump->buffer + pos, count);
 311
 312         /* You may think we could free the dump buffer now and retrieve
 313          * it again later if needed, but due to current firmware limitation,
 314          * that's not the case. So, once read into userspace once,
 315          * we keep the dump around until it's acknowledged by userspace.
 316          */
 317
 318         return count;
 319 }
 320
 321 static void create_dump_obj(uint32_t id, size_t size, uint32_t type)
 322 {
 323         struct dump_obj *dump;
 324         int rc;
 325
 326         dump = kzalloc(sizeof(*dump), GFP_KERNEL);
 327         if (!dump)
 328                 return;
 329
 330         dump->kobj.kset = dump_kset;
 331
 332         kobject_init(&dump->kobj, &dump_ktype);
 333
 334         sysfs_bin_attr_init(&dump->dump_attr);
 335
 336         dump->dump_attr.attr.name = "dump";
 337         dump->dump_attr.attr.mode = 0400;
 338         dump->dump_attr.size = size;
 339         dump->dump_attr.read = dump_attr_read;
 340
 341         dump->id = id;
 342         dump->size = size;
 343         dump->type = type;
 344
 345         rc = kobject_add(&dump->kobj, NULL, "0x%x-0x%x", type, id);
 346         if (rc) {
 347                 kobject_put(&dump->kobj);
 348                 return;
 349         }
 350
 351         /*
 352          * As soon as the sysfs file for this dump is created/activated there is
 353          * a chance the opal_errd daemon (or any userspace) might read and
 354          * acknowledge the dump before kobject_uevent() is called. If that
 355          * happens then there is a potential race between
 356          * dump_ack_store->kobject_put() and kobject_uevent() which leads to a
 357          * use-after-free of a kernfs object resulting in a kernel crash.
 358          *
 359          * To avoid that, we need to take a reference on behalf of the bin file,
 360          * so that our reference remains valid while we call kobject_uevent().
 361          * We then drop our reference before exiting the function, leaving the
 362          * bin file to drop the last reference (if it hasn't already).
 363          */
 364
 365         /* Take a reference for the bin file */
 366         kobject_get(&dump->kobj);
 367         rc = sysfs_create_bin_file(&dump->kobj, &dump->dump_attr);
 368         if (rc == 0) {
 369                 kobject_uevent(&dump->kobj, KOBJ_ADD);
 370
 371                 pr_info("%s: New platform dump. ID = 0x%x Size %u\n",
 372                         __func__, dump->id, dump->size);
 373         } else {
 374                 /* Drop reference count taken for bin file */
 375                 kobject_put(&dump->kobj);
 376         }
 377
 378         /* Drop our reference */
 379         kobject_put(&dump->kobj);
 380         return;
 381 }
 382
 383 static irqreturn_t process_dump(int irq, void *data)
 384 {
 385         int rc;
 386         uint32_t dump_id, dump_size, dump_type;
 387         char name[22];
 388         struct kobject *kobj;
 389
 390         rc = dump_read_info(&dump_id, &dump_size, &dump_type);
 391         if (rc != OPAL_SUCCESS)
 392                 return IRQ_HANDLED;
 393
 394         sprintf(name, "0x%x-0x%x", dump_type, dump_id);
 395
 396         /* we may get notified twice, let's handle
 397          * that gracefully and not create two conflicting
 398          * entries.
 399          */
 400         kobj = kset_find_obj(dump_kset, name);
 401         if (kobj) {
 402                 /* Drop reference added by kset_find_obj() */
 403                 kobject_put(kobj);
 404                 return IRQ_HANDLED;
 405         }
 406
 407         create_dump_obj(dump_id, dump_size, dump_type);
 408
 409         return IRQ_HANDLED;
 410 }
 411
 412 void __init opal_platform_dump_init(void)
 413 {
 414         int rc;
 415         int dump_irq;
 416
 417         /* ELOG not supported by firmware */
 418         if (!opal_check_token(OPAL_DUMP_READ))
 419                 return;
 420
 421         dump_kset = kset_create_and_add("dump", NULL, opal_kobj);
 422         if (!dump_kset) {
 423                 pr_warn("%s: Failed to create dump kset\n", __func__);
 424                 return;
 425         }
 426
 427         rc = sysfs_create_group(&dump_kset->kobj, &initiate_attr_group);
 428         if (rc) {
 429                 pr_warn("%s: Failed to create initiate dump attr group\n",
 430                         __func__);
 431                 kobject_put(&dump_kset->kobj);
 432                 return;
 433         }
 434
 435         dump_irq = opal_event_request(ilog2(OPAL_EVENT_DUMP_AVAIL));
 436         if (!dump_irq) {
 437                 pr_err("%s: Can't register OPAL event irq (%d)\n",
 438                        __func__, dump_irq);
 439                 return;
 440         }
 441
 442         rc = request_threaded_irq(dump_irq, NULL, process_dump,
 443                                 IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
 444                                 "opal-dump", NULL);
 445         if (rc) {
 446                 pr_err("%s: Can't request OPAL event irq (%d)\n",
 447                        __func__, rc);
 448                 return;
 449         }
 450
 451         if (opal_check_token(OPAL_DUMP_RESEND))
 452                 opal_dump_resend_notification();
 453 }