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

   1 /*
   2  * PowerNV OPAL Dump Interface
   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
  12 #include <linux/kobject.h>
  13 #include <linux/mm.h>
  14 #include <linux/slab.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/delay.h>
  18 #include <linux/interrupt.h>
  19
  20 #include <asm/opal.h>
  21
  22 #define DUMP_TYPE_FSP   0x01
  23
  24 struct dump_obj {
  25         struct kobject  kobj;
  26         struct bin_attribute dump_attr;
  27         uint32_t        id;  /* becomes object name */
  28         uint32_t        type;
  29         uint32_t        size;
  30         char            *buffer;
  31 };
  32 #define to_dump_obj(x) container_of(x, struct dump_obj, kobj)
  33
  34 struct dump_attribute {
  35         struct attribute attr;
  36         ssize_t (*show)(struct dump_obj *dump, struct dump_attribute *attr,
  37                         char *buf);
  38         ssize_t (*store)(struct dump_obj *dump, struct dump_attribute *attr,
  39                          const char *buf, size_t count);
  40 };
  41 #define to_dump_attr(x) container_of(x, struct dump_attribute, attr)
  42
  43 static ssize_t dump_id_show(struct dump_obj *dump_obj,
  44                             struct dump_attribute *attr,
  45                             char *buf)
  46 {
  47         return sprintf(buf, "0x%x\n", dump_obj->id);
  48 }
  49
  50 static const char* dump_type_to_string(uint32_t type)
  51 {
  52         switch (type) {
  53         case 0x01: return "SP Dump";
  54         case 0x02: return "System/Platform Dump";
  55         case 0x03: return "SMA Dump";
  56         default: return "unknown";
  57         }
  58 }
  59
  60 static ssize_t dump_type_show(struct dump_obj *dump_obj,
  61                               struct dump_attribute *attr,
  62                               char *buf)
  63 {
  64
  65         return sprintf(buf, "0x%x %s\n", dump_obj->type,
  66                        dump_type_to_string(dump_obj->type));
  67 }
  68
  69 static ssize_t dump_ack_show(struct dump_obj *dump_obj,
  70                              struct dump_attribute *attr,
  71                              char *buf)
  72 {
  73         return sprintf(buf, "ack - acknowledge dump\n");
  74 }
  75
  76 /*
  77  * Send acknowledgement to OPAL
  78  */
  79 static int64_t dump_send_ack(uint32_t dump_id)
  80 {
  81         int rc;
  82
  83         rc = opal_dump_ack(dump_id);
  84         if (rc)
  85                 pr_warn("%s: Failed to send ack to Dump ID 0x%x (%d)\n",
  86                         __func__, dump_id, rc);
  87         return rc;
  88 }
  89
  90 static ssize_t dump_ack_store(struct dump_obj *dump_obj,
  91                               struct dump_attribute *attr,
  92                               const char *buf,
  93                               size_t count)
  94 {
  95         dump_send_ack(dump_obj->id);
  96         sysfs_remove_file_self(&dump_obj->kobj, &attr->attr);
  97         kobject_put(&dump_obj->kobj);
  98         return count;
  99 }
 100
 101 /* Attributes of a dump
 102  * The binary attribute of the dump itself is dynamic
 103  * due to the dynamic size of the dump
 104  */
 105 static struct dump_attribute id_attribute =
 106         __ATTR(id, S_IRUGO, dump_id_show, NULL);
 107 static struct dump_attribute type_attribute =
 108         __ATTR(type, S_IRUGO, dump_type_show, NULL);
 109 static struct dump_attribute ack_attribute =
 110         __ATTR(acknowledge, 0660, dump_ack_show, dump_ack_store);
 111
 112 static ssize_t init_dump_show(struct dump_obj *dump_obj,
 113                               struct dump_attribute *attr,
 114                               char *buf)
 115 {
 116         return sprintf(buf, "1 - initiate Service Processor(FSP) dump\n");
 117 }
 118
 119 static int64_t dump_fips_init(uint8_t type)
 120 {
 121         int rc;
 122
 123         rc = opal_dump_init(type);
 124         if (rc)
 125                 pr_warn("%s: Failed to initiate FSP dump (%d)\n",
 126                         __func__, rc);
 127         return rc;
 128 }
 129
 130 static ssize_t init_dump_store(struct dump_obj *dump_obj,
 131                                struct dump_attribute *attr,
 132                                const char *buf,
 133                                size_t count)
 134 {
 135         int rc;
 136
 137         rc = dump_fips_init(DUMP_TYPE_FSP);
 138         if (rc == OPAL_SUCCESS)
 139                 pr_info("%s: Initiated FSP dump\n", __func__);
 140
 141         return count;
 142 }
 143
 144 static struct dump_attribute initiate_attribute =
 145         __ATTR(initiate_dump, 0600, init_dump_show, init_dump_store);
 146
 147 static struct attribute *initiate_attrs[] = {
 148         &initiate_attribute.attr,
 149         NULL,
 150 };
 151
 152 static struct attribute_group initiate_attr_group = {
 153         .attrs = initiate_attrs,
 154 };
 155
 156 static struct kset *dump_kset;
 157
 158 static ssize_t dump_attr_show(struct kobject *kobj,
 159                               struct attribute *attr,
 160                               char *buf)
 161 {
 162         struct dump_attribute *attribute;
 163         struct dump_obj *dump;
 164
 165         attribute = to_dump_attr(attr);
 166         dump = to_dump_obj(kobj);
 167
 168         if (!attribute->show)
 169                 return -EIO;
 170
 171         return attribute->show(dump, attribute, buf);
 172 }
 173
 174 static ssize_t dump_attr_store(struct kobject *kobj,
 175                                struct attribute *attr,
 176                                const char *buf, size_t len)
 177 {
 178         struct dump_attribute *attribute;
 179         struct dump_obj *dump;
 180
 181         attribute = to_dump_attr(attr);
 182         dump = to_dump_obj(kobj);
 183
 184         if (!attribute->store)
 185                 return -EIO;
 186
 187         return attribute->store(dump, attribute, buf, len);
 188 }
 189
 190 static const struct sysfs_ops dump_sysfs_ops = {
 191         .show = dump_attr_show,
 192         .store = dump_attr_store,
 193 };
 194
 195 static void dump_release(struct kobject *kobj)
 196 {
 197         struct dump_obj *dump;
 198
 199         dump = to_dump_obj(kobj);
 200         vfree(dump->buffer);
 201         kfree(dump);
 202 }
 203
 204 static struct attribute *dump_default_attrs[] = {
 205         &id_attribute.attr,
 206         &type_attribute.attr,
 207         &ack_attribute.attr,
 208         NULL,
 209 };
 210
 211 static struct kobj_type dump_ktype = {
 212         .sysfs_ops = &dump_sysfs_ops,
 213         .release = &dump_release,
 214         .default_attrs = dump_default_attrs,
 215 };
 216
 217 static int64_t dump_read_info(uint32_t *dump_id, uint32_t *dump_size, uint32_t *dump_type)
 218 {
 219         __be32 id, size, type;
 220         int rc;
 221
 222         type = cpu_to_be32(0xffffffff);
 223
 224         rc = opal_dump_info2(&id, &size, &type);
 225         if (rc == OPAL_PARAMETER)
 226                 rc = opal_dump_info(&id, &size);
 227
 228         *dump_id = be32_to_cpu(id);
 229         *dump_size = be32_to_cpu(size);
 230         *dump_type = be32_to_cpu(type);
 231
 232         if (rc)
 233                 pr_warn("%s: Failed to get dump info (%d)\n",
 234                         __func__, rc);
 235         return rc;
 236 }
 237
 238 static int64_t dump_read_data(struct dump_obj *dump)
 239 {
 240         struct opal_sg_list *list;
 241         uint64_t addr;
 242         int64_t rc;
 243
 244         /* Allocate memory */
 245         dump->buffer = vzalloc(PAGE_ALIGN(dump->size));
 246         if (!dump->buffer) {
 247                 pr_err("%s : Failed to allocate memory\n", __func__);
 248                 rc = -ENOMEM;
 249                 goto out;
 250         }
 251
 252         /* Generate SG list */
 253         list = opal_vmalloc_to_sg_list(dump->buffer, dump->size);
 254         if (!list) {
 255                 rc = -ENOMEM;
 256                 goto out;
 257         }
 258
 259         /* First entry address */
 260         addr = __pa(list);
 261
 262         /* Fetch data */
 263         rc = OPAL_BUSY_EVENT;
 264         while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
 265                 rc = opal_dump_read(dump->id, addr);
 266                 if (rc == OPAL_BUSY_EVENT) {
 267                         opal_poll_events(NULL);
 268                         msleep(20);
 269                 }
 270         }
 271
 272         if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL)
 273                 pr_warn("%s: Extract dump failed for ID 0x%x\n",
 274                         __func__, dump->id);
 275
 276         /* Free SG list */
 277         opal_free_sg_list(list);
 278
 279 out:
 280         return rc;
 281 }
 282
 283 static ssize_t dump_attr_read(struct file *filep, struct kobject *kobj,
 284                               struct bin_attribute *bin_attr,
 285                               char *buffer, loff_t pos, size_t count)
 286 {
 287         ssize_t rc;
 288
 289         struct dump_obj *dump = to_dump_obj(kobj);
 290
 291         if (!dump->buffer) {
 292                 rc = dump_read_data(dump);
 293
 294                 if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL) {
 295                         vfree(dump->buffer);
 296                         dump->buffer = NULL;
 297
 298                         return -EIO;
 299                 }
 300                 if (rc == OPAL_PARTIAL) {
 301                         /* On a partial read, we just return EIO
 302                          * and rely on userspace to ask us to try
 303                          * again.
 304                          */
 305                         pr_info("%s: Platform dump partially read. ID = 0x%x\n",
 306                                 __func__, dump->id);
 307                         return -EIO;
 308                 }
 309         }
 310
 311         memcpy(buffer, dump->buffer + pos, count);
 312
 313         /* You may think we could free the dump buffer now and retrieve
 314          * it again later if needed, but due to current firmware limitation,
 315          * that's not the case. So, once read into userspace once,
 316          * we keep the dump around until it's acknowledged by userspace.
 317          */
 318
 319         return count;
 320 }
 321
 322 static void create_dump_obj(uint32_t id, size_t size, uint32_t type)
 323 {
 324         struct dump_obj *dump;
 325         int rc;
 326
 327         dump = kzalloc(sizeof(*dump), GFP_KERNEL);
 328         if (!dump)
 329                 return;
 330
 331         dump->kobj.kset = dump_kset;
 332
 333         kobject_init(&dump->kobj, &dump_ktype);
 334
 335         sysfs_bin_attr_init(&dump->dump_attr);
 336
 337         dump->dump_attr.attr.name = "dump";
 338         dump->dump_attr.attr.mode = 0400;
 339         dump->dump_attr.size = size;
 340         dump->dump_attr.read = dump_attr_read;
 341
 342         dump->id = id;
 343         dump->size = size;
 344         dump->type = type;
 345
 346         rc = kobject_add(&dump->kobj, NULL, "0x%x-0x%x", type, id);
 347         if (rc) {
 348                 kobject_put(&dump->kobj);
 349                 return;
 350         }
 351
 352         /*
 353          * As soon as the sysfs file for this dump is created/activated there is
 354          * a chance the opal_errd daemon (or any userspace) might read and
 355          * acknowledge the dump before kobject_uevent() is called. If that
 356          * happens then there is a potential race between
 357          * dump_ack_store->kobject_put() and kobject_uevent() which leads to a
 358          * use-after-free of a kernfs object resulting in a kernel crash.
 359          *
 360          * To avoid that, we need to take a reference on behalf of the bin file,
 361          * so that our reference remains valid while we call kobject_uevent().
 362          * We then drop our reference before exiting the function, leaving the
 363          * bin file to drop the last reference (if it hasn't already).
 364          */
 365
 366         /* Take a reference for the bin file */
 367         kobject_get(&dump->kobj);
 368         rc = sysfs_create_bin_file(&dump->kobj, &dump->dump_attr);
 369         if (rc == 0) {
 370                 kobject_uevent(&dump->kobj, KOBJ_ADD);
 371
 372                 pr_info("%s: New platform dump. ID = 0x%x Size %u\n",
 373                         __func__, dump->id, dump->size);
 374         } else {
 375                 /* Drop reference count taken for bin file */
 376                 kobject_put(&dump->kobj);
 377         }
 378
 379         /* Drop our reference */
 380         kobject_put(&dump->kobj);
 381         return;
 382 }
 383
 384 static irqreturn_t process_dump(int irq, void *data)
 385 {
 386         int rc;
 387         uint32_t dump_id, dump_size, dump_type;
 388         char name[22];
 389         struct kobject *kobj;
 390
 391         rc = dump_read_info(&dump_id, &dump_size, &dump_type);
 392         if (rc != OPAL_SUCCESS)
 393                 return IRQ_HANDLED;
 394
 395         sprintf(name, "0x%x-0x%x", dump_type, dump_id);
 396
 397         /* we may get notified twice, let's handle
 398          * that gracefully and not create two conflicting
 399          * entries.
 400          */
 401         kobj = kset_find_obj(dump_kset, name);
 402         if (kobj) {
 403                 /* Drop reference added by kset_find_obj() */
 404                 kobject_put(kobj);
 405                 return IRQ_HANDLED;
 406         }
 407
 408         create_dump_obj(dump_id, dump_size, dump_type);
 409
 410         return IRQ_HANDLED;
 411 }
 412
 413 void __init opal_platform_dump_init(void)
 414 {
 415         int rc;
 416         int dump_irq;
 417
 418         /* ELOG not supported by firmware */
 419         if (!opal_check_token(OPAL_DUMP_READ))
 420                 return;
 421
 422         dump_kset = kset_create_and_add("dump", NULL, opal_kobj);
 423         if (!dump_kset) {
 424                 pr_warn("%s: Failed to create dump kset\n", __func__);
 425                 return;
 426         }
 427
 428         rc = sysfs_create_group(&dump_kset->kobj, &initiate_attr_group);
 429         if (rc) {
 430                 pr_warn("%s: Failed to create initiate dump attr group\n",
 431                         __func__);
 432                 kobject_put(&dump_kset->kobj);
 433                 return;
 434         }
 435
 436         dump_irq = opal_event_request(ilog2(OPAL_EVENT_DUMP_AVAIL));
 437         if (!dump_irq) {
 438                 pr_err("%s: Can't register OPAL event irq (%d)\n",
 439                        __func__, dump_irq);
 440                 return;
 441         }
 442
 443         rc = request_threaded_irq(dump_irq, NULL, process_dump,
 444                                 IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
 445                                 "opal-dump", NULL);
 446         if (rc) {
 447                 pr_err("%s: Can't request OPAL event irq (%d)\n",
 448                        __func__, rc);
 449                 return;
 450         }
 451
 452         if (opal_check_token(OPAL_DUMP_RESEND))
 453                 opal_dump_resend_notification();
 454 }