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         /*
  92          * Try to self remove this attribute. If we are successful,
  93          * delete the kobject itself.
  94          */
  95         if (sysfs_remove_file_self(&dump_obj->kobj, &attr->attr)) {
  96                 dump_send_ack(dump_obj->id);
  97                 kobject_put(&dump_obj->kobj);
  98         }
  99         return count;
 100 }
 101
 102 /* Attributes of a dump
 103  * The binary attribute of the dump itself is dynamic
 104  * due to the dynamic size of the dump
 105  */
 106 static struct dump_attribute id_attribute =
 107         __ATTR(id, 0444, dump_id_show, NULL);
 108 static struct dump_attribute type_attribute =
 109         __ATTR(type, 0444, dump_type_show, NULL);
 110 static struct dump_attribute ack_attribute =
 111         __ATTR(acknowledge, 0660, dump_ack_show, dump_ack_store);
 112
 113 static ssize_t init_dump_show(struct dump_obj *dump_obj,
 114                               struct dump_attribute *attr,
 115                               char *buf)
 116 {
 117         return sprintf(buf, "1 - initiate Service Processor(FSP) dump\n");
 118 }
 119
 120 static int64_t dump_fips_init(uint8_t type)
 121 {
 122         int rc;
 123
 124         rc = opal_dump_init(type);
 125         if (rc)
 126                 pr_warn("%s: Failed to initiate FSP dump (%d)\n",
 127                         __func__, rc);
 128         return rc;
 129 }
 130
 131 static ssize_t init_dump_store(struct dump_obj *dump_obj,
 132                                struct dump_attribute *attr,
 133                                const char *buf,
 134                                size_t count)
 135 {
 136         int rc;
 137
 138         rc = dump_fips_init(DUMP_TYPE_FSP);
 139         if (rc == OPAL_SUCCESS)
 140                 pr_info("%s: Initiated FSP dump\n", __func__);
 141
 142         return count;
 143 }
 144
 145 static struct dump_attribute initiate_attribute =
 146         __ATTR(initiate_dump, 0600, init_dump_show, init_dump_store);
 147
 148 static struct attribute *initiate_attrs[] = {
 149         &initiate_attribute.attr,
 150         NULL,
 151 };
 152
 153 static struct attribute_group initiate_attr_group = {
 154         .attrs = initiate_attrs,
 155 };
 156
 157 static struct kset *dump_kset;
 158
 159 static ssize_t dump_attr_show(struct kobject *kobj,
 160                               struct attribute *attr,
 161                               char *buf)
 162 {
 163         struct dump_attribute *attribute;
 164         struct dump_obj *dump;
 165
 166         attribute = to_dump_attr(attr);
 167         dump = to_dump_obj(kobj);
 168
 169         if (!attribute->show)
 170                 return -EIO;
 171
 172         return attribute->show(dump, attribute, buf);
 173 }
 174
 175 static ssize_t dump_attr_store(struct kobject *kobj,
 176                                struct attribute *attr,
 177                                const char *buf, size_t len)
 178 {
 179         struct dump_attribute *attribute;
 180         struct dump_obj *dump;
 181
 182         attribute = to_dump_attr(attr);
 183         dump = to_dump_obj(kobj);
 184
 185         if (!attribute->store)
 186                 return -EIO;
 187
 188         return attribute->store(dump, attribute, buf, len);
 189 }
 190
 191 static const struct sysfs_ops dump_sysfs_ops = {
 192         .show = dump_attr_show,
 193         .store = dump_attr_store,
 194 };
 195
 196 static void dump_release(struct kobject *kobj)
 197 {
 198         struct dump_obj *dump;
 199
 200         dump = to_dump_obj(kobj);
 201         vfree(dump->buffer);
 202         kfree(dump);
 203 }
 204
 205 static struct attribute *dump_default_attrs[] = {
 206         &id_attribute.attr,
 207         &type_attribute.attr,
 208         &ack_attribute.attr,
 209         NULL,
 210 };
 211
 212 static struct kobj_type dump_ktype = {
 213         .sysfs_ops = &dump_sysfs_ops,
 214         .release = &dump_release,
 215         .default_attrs = dump_default_attrs,
 216 };
 217
 218 static int64_t dump_read_info(uint32_t *dump_id, uint32_t *dump_size, uint32_t *dump_type)
 219 {
 220         __be32 id, size, type;
 221         int rc;
 222
 223         type = cpu_to_be32(0xffffffff);
 224
 225         rc = opal_dump_info2(&id, &size, &type);
 226         if (rc == OPAL_PARAMETER)
 227                 rc = opal_dump_info(&id, &size);
 228
 229         if (rc) {
 230                 pr_warn("%s: Failed to get dump info (%d)\n",
 231                         __func__, rc);
 232                 return rc;
 233         }
 234
 235         *dump_id = be32_to_cpu(id);
 236         *dump_size = be32_to_cpu(size);
 237         *dump_type = be32_to_cpu(type);
 238
 239         return rc;
 240 }
 241
 242 static int64_t dump_read_data(struct dump_obj *dump)
 243 {
 244         struct opal_sg_list *list;
 245         uint64_t addr;
 246         int64_t rc;
 247
 248         /* Allocate memory */
 249         dump->buffer = vzalloc(PAGE_ALIGN(dump->size));
 250         if (!dump->buffer) {
 251                 pr_err("%s : Failed to allocate memory\n", __func__);
 252                 rc = -ENOMEM;
 253                 goto out;
 254         }
 255
 256         /* Generate SG list */
 257         list = opal_vmalloc_to_sg_list(dump->buffer, dump->size);
 258         if (!list) {
 259                 rc = -ENOMEM;
 260                 goto out;
 261         }
 262
 263         /* First entry address */
 264         addr = __pa(list);
 265
 266         /* Fetch data */
 267         rc = OPAL_BUSY_EVENT;
 268         while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
 269                 rc = opal_dump_read(dump->id, addr);
 270                 if (rc == OPAL_BUSY_EVENT) {
 271                         opal_poll_events(NULL);
 272                         msleep(20);
 273                 }
 274         }
 275
 276         if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL)
 277                 pr_warn("%s: Extract dump failed for ID 0x%x\n",
 278                         __func__, dump->id);
 279
 280         /* Free SG list */
 281         opal_free_sg_list(list);
 282
 283 out:
 284         return rc;
 285 }
 286
 287 static ssize_t dump_attr_read(struct file *filep, struct kobject *kobj,
 288                               struct bin_attribute *bin_attr,
 289                               char *buffer, loff_t pos, size_t count)
 290 {
 291         ssize_t rc;
 292
 293         struct dump_obj *dump = to_dump_obj(kobj);
 294
 295         if (!dump->buffer) {
 296                 rc = dump_read_data(dump);
 297
 298                 if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL) {
 299                         vfree(dump->buffer);
 300                         dump->buffer = NULL;
 301
 302                         return -EIO;
 303                 }
 304                 if (rc == OPAL_PARTIAL) {
 305                         /* On a partial read, we just return EIO
 306                          * and rely on userspace to ask us to try
 307                          * again.
 308                          */
 309                         pr_info("%s: Platform dump partially read. ID = 0x%x\n",
 310                                 __func__, dump->id);
 311                         return -EIO;
 312                 }
 313         }
 314
 315         memcpy(buffer, dump->buffer + pos, count);
 316
 317         /* You may think we could free the dump buffer now and retrieve
 318          * it again later if needed, but due to current firmware limitation,
 319          * that's not the case. So, once read into userspace once,
 320          * we keep the dump around until it's acknowledged by userspace.
 321          */
 322
 323         return count;
 324 }
 325
 326 static void create_dump_obj(uint32_t id, size_t size, uint32_t type)
 327 {
 328         struct dump_obj *dump;
 329         int rc;
 330
 331         dump = kzalloc(sizeof(*dump), GFP_KERNEL);
 332         if (!dump)
 333                 return;
 334
 335         dump->kobj.kset = dump_kset;
 336
 337         kobject_init(&dump->kobj, &dump_ktype);
 338
 339         sysfs_bin_attr_init(&dump->dump_attr);
 340
 341         dump->dump_attr.attr.name = "dump";
 342         dump->dump_attr.attr.mode = 0400;
 343         dump->dump_attr.size = size;
 344         dump->dump_attr.read = dump_attr_read;
 345
 346         dump->id = id;
 347         dump->size = size;
 348         dump->type = type;
 349
 350         rc = kobject_add(&dump->kobj, NULL, "0x%x-0x%x", type, id);
 351         if (rc) {
 352                 kobject_put(&dump->kobj);
 353                 return;
 354         }
 355
 356         /*
 357          * As soon as the sysfs file for this dump is created/activated there is
 358          * a chance the opal_errd daemon (or any userspace) might read and
 359          * acknowledge the dump before kobject_uevent() is called. If that
 360          * happens then there is a potential race between
 361          * dump_ack_store->kobject_put() and kobject_uevent() which leads to a
 362          * use-after-free of a kernfs object resulting in a kernel crash.
 363          *
 364          * To avoid that, we need to take a reference on behalf of the bin file,
 365          * so that our reference remains valid while we call kobject_uevent().
 366          * We then drop our reference before exiting the function, leaving the
 367          * bin file to drop the last reference (if it hasn't already).
 368          */
 369
 370         /* Take a reference for the bin file */
 371         kobject_get(&dump->kobj);
 372         rc = sysfs_create_bin_file(&dump->kobj, &dump->dump_attr);
 373         if (rc == 0) {
 374                 kobject_uevent(&dump->kobj, KOBJ_ADD);
 375
 376                 pr_info("%s: New platform dump. ID = 0x%x Size %u\n",
 377                         __func__, dump->id, dump->size);
 378         } else {
 379                 /* Drop reference count taken for bin file */
 380                 kobject_put(&dump->kobj);
 381         }
 382
 383         /* Drop our reference */
 384         kobject_put(&dump->kobj);
 385         return;
 386 }
 387
 388 static irqreturn_t process_dump(int irq, void *data)
 389 {
 390         int rc;
 391         uint32_t dump_id, dump_size, dump_type;
 392         char name[22];
 393         struct kobject *kobj;
 394
 395         rc = dump_read_info(&dump_id, &dump_size, &dump_type);
 396         if (rc != OPAL_SUCCESS)
 397                 return IRQ_HANDLED;
 398
 399         sprintf(name, "0x%x-0x%x", dump_type, dump_id);
 400
 401         /* we may get notified twice, let's handle
 402          * that gracefully and not create two conflicting
 403          * entries.
 404          */
 405         kobj = kset_find_obj(dump_kset, name);
 406         if (kobj) {
 407                 /* Drop reference added by kset_find_obj() */
 408                 kobject_put(kobj);
 409                 return IRQ_HANDLED;
 410         }
 411
 412         create_dump_obj(dump_id, dump_size, dump_type);
 413
 414         return IRQ_HANDLED;
 415 }
 416
 417 void __init opal_platform_dump_init(void)
 418 {
 419         int rc;
 420         int dump_irq;
 421
 422         /* ELOG not supported by firmware */
 423         if (!opal_check_token(OPAL_DUMP_READ))
 424                 return;
 425
 426         dump_kset = kset_create_and_add("dump", NULL, opal_kobj);
 427         if (!dump_kset) {
 428                 pr_warn("%s: Failed to create dump kset\n", __func__);
 429                 return;
 430         }
 431
 432         rc = sysfs_create_group(&dump_kset->kobj, &initiate_attr_group);
 433         if (rc) {
 434                 pr_warn("%s: Failed to create initiate dump attr group\n",
 435                         __func__);
 436                 kobject_put(&dump_kset->kobj);
 437                 return;
 438         }
 439
 440         dump_irq = opal_event_request(ilog2(OPAL_EVENT_DUMP_AVAIL));
 441         if (!dump_irq) {
 442                 pr_err("%s: Can't register OPAL event irq (%d)\n",
 443                        __func__, dump_irq);
 444                 return;
 445         }
 446
 447         rc = request_threaded_irq(dump_irq, NULL, process_dump,
 448                                 IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
 449                                 "opal-dump", NULL);
 450         if (rc) {
 451                 pr_err("%s: Can't request OPAL event irq (%d)\n",
 452                        __func__, rc);
 453                 return;
 454         }
 455
 456         if (opal_check_token(OPAL_DUMP_RESEND))
 457                 opal_dump_resend_notification();
 458 }