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 const 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 ATTRIBUTE_GROUPS(dump_default);
 212
 213 static struct kobj_type dump_ktype = {
 214         .sysfs_ops = &dump_sysfs_ops,
 215         .release = &dump_release,
 216         .default_groups = dump_default_groups,
 217 };
 218
 219 static int64_t dump_read_info(uint32_t *dump_id, uint32_t *dump_size, uint32_t *dump_type)
 220 {
 221         __be32 id, size, type;
 222         int rc;
 223
 224         type = cpu_to_be32(0xffffffff);
 225
 226         rc = opal_dump_info2(&id, &size, &type);
 227         if (rc == OPAL_PARAMETER)
 228                 rc = opal_dump_info(&id, &size);
 229
 230         if (rc) {
 231                 pr_warn("%s: Failed to get dump info (%d)\n",
 232                         __func__, rc);
 233                 return rc;
 234         }
 235
 236         *dump_id = be32_to_cpu(id);
 237         *dump_size = be32_to_cpu(size);
 238         *dump_type = be32_to_cpu(type);
 239
 240         return rc;
 241 }
 242
 243 static int64_t dump_read_data(struct dump_obj *dump)
 244 {
 245         struct opal_sg_list *list;
 246         uint64_t addr;
 247         int64_t rc;
 248
 249         /* Allocate memory */
 250         dump->buffer = vzalloc(PAGE_ALIGN(dump->size));
 251         if (!dump->buffer) {
 252                 pr_err("%s : Failed to allocate memory\n", __func__);
 253                 rc = -ENOMEM;
 254                 goto out;
 255         }
 256
 257         /* Generate SG list */
 258         list = opal_vmalloc_to_sg_list(dump->buffer, dump->size);
 259         if (!list) {
 260                 rc = -ENOMEM;
 261                 goto out;
 262         }
 263
 264         /* First entry address */
 265         addr = __pa(list);
 266
 267         /* Fetch data */
 268         rc = OPAL_BUSY_EVENT;
 269         while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
 270                 rc = opal_dump_read(dump->id, addr);
 271                 if (rc == OPAL_BUSY_EVENT) {
 272                         opal_poll_events(NULL);
 273                         msleep(20);
 274                 }
 275         }
 276
 277         if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL)
 278                 pr_warn("%s: Extract dump failed for ID 0x%x\n",
 279                         __func__, dump->id);
 280
 281         /* Free SG list */
 282         opal_free_sg_list(list);
 283
 284 out:
 285         return rc;
 286 }
 287
 288 static ssize_t dump_attr_read(struct file *filep, struct kobject *kobj,
 289                               struct bin_attribute *bin_attr,
 290                               char *buffer, loff_t pos, size_t count)
 291 {
 292         ssize_t rc;
 293
 294         struct dump_obj *dump = to_dump_obj(kobj);
 295
 296         if (!dump->buffer) {
 297                 rc = dump_read_data(dump);
 298
 299                 if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL) {
 300                         vfree(dump->buffer);
 301                         dump->buffer = NULL;
 302
 303                         return -EIO;
 304                 }
 305                 if (rc == OPAL_PARTIAL) {
 306                         /* On a partial read, we just return EIO
 307                          * and rely on userspace to ask us to try
 308                          * again.
 309                          */
 310                         pr_info("%s: Platform dump partially read. ID = 0x%x\n",
 311                                 __func__, dump->id);
 312                         return -EIO;
 313                 }
 314         }
 315
 316         memcpy(buffer, dump->buffer + pos, count);
 317
 318         /* You may think we could free the dump buffer now and retrieve
 319          * it again later if needed, but due to current firmware limitation,
 320          * that's not the case. So, once read into userspace once,
 321          * we keep the dump around until it's acknowledged by userspace.
 322          */
 323
 324         return count;
 325 }
 326
 327 static void create_dump_obj(uint32_t id, size_t size, uint32_t type)
 328 {
 329         struct dump_obj *dump;
 330         int rc;
 331
 332         dump = kzalloc(sizeof(*dump), GFP_KERNEL);
 333         if (!dump)
 334                 return;
 335
 336         dump->kobj.kset = dump_kset;
 337
 338         kobject_init(&dump->kobj, &dump_ktype);
 339
 340         sysfs_bin_attr_init(&dump->dump_attr);
 341
 342         dump->dump_attr.attr.name = "dump";
 343         dump->dump_attr.attr.mode = 0400;
 344         dump->dump_attr.size = size;
 345         dump->dump_attr.read = dump_attr_read;
 346
 347         dump->id = id;
 348         dump->size = size;
 349         dump->type = type;
 350
 351         rc = kobject_add(&dump->kobj, NULL, "0x%x-0x%x", type, id);
 352         if (rc) {
 353                 kobject_put(&dump->kobj);
 354                 return;
 355         }
 356
 357         /*
 358          * As soon as the sysfs file for this dump is created/activated there is
 359          * a chance the opal_errd daemon (or any userspace) might read and
 360          * acknowledge the dump before kobject_uevent() is called. If that
 361          * happens then there is a potential race between
 362          * dump_ack_store->kobject_put() and kobject_uevent() which leads to a
 363          * use-after-free of a kernfs object resulting in a kernel crash.
 364          *
 365          * To avoid that, we need to take a reference on behalf of the bin file,
 366          * so that our reference remains valid while we call kobject_uevent().
 367          * We then drop our reference before exiting the function, leaving the
 368          * bin file to drop the last reference (if it hasn't already).
 369          */
 370
 371         /* Take a reference for the bin file */
 372         kobject_get(&dump->kobj);
 373         rc = sysfs_create_bin_file(&dump->kobj, &dump->dump_attr);
 374         if (rc == 0) {
 375                 kobject_uevent(&dump->kobj, KOBJ_ADD);
 376
 377                 pr_info("%s: New platform dump. ID = 0x%x Size %u\n",
 378                         __func__, dump->id, dump->size);
 379         } else {
 380                 /* Drop reference count taken for bin file */
 381                 kobject_put(&dump->kobj);
 382         }
 383
 384         /* Drop our reference */
 385         kobject_put(&dump->kobj);
 386         return;
 387 }
 388
 389 static irqreturn_t process_dump(int irq, void *data)
 390 {
 391         int rc;
 392         uint32_t dump_id, dump_size, dump_type;
 393         char name[22];
 394         struct kobject *kobj;
 395
 396         rc = dump_read_info(&dump_id, &dump_size, &dump_type);
 397         if (rc != OPAL_SUCCESS)
 398                 return IRQ_HANDLED;
 399
 400         sprintf(name, "0x%x-0x%x", dump_type, dump_id);
 401
 402         /* we may get notified twice, let's handle
 403          * that gracefully and not create two conflicting
 404          * entries.
 405          */
 406         kobj = kset_find_obj(dump_kset, name);
 407         if (kobj) {
 408                 /* Drop reference added by kset_find_obj() */
 409                 kobject_put(kobj);
 410                 return IRQ_HANDLED;
 411         }
 412
 413         create_dump_obj(dump_id, dump_size, dump_type);
 414
 415         return IRQ_HANDLED;
 416 }
 417
 418 void __init opal_platform_dump_init(void)
 419 {
 420         int rc;
 421         int dump_irq;
 422
 423         /* Dump not supported by firmware */
 424         if (!opal_check_token(OPAL_DUMP_READ))
 425                 return;
 426
 427         dump_kset = kset_create_and_add("dump", NULL, opal_kobj);
 428         if (!dump_kset) {
 429                 pr_warn("%s: Failed to create dump kset\n", __func__);
 430                 return;
 431         }
 432
 433         rc = sysfs_create_group(&dump_kset->kobj, &initiate_attr_group);
 434         if (rc) {
 435                 pr_warn("%s: Failed to create initiate dump attr group\n",
 436                         __func__);
 437                 kobject_put(&dump_kset->kobj);
 438                 return;
 439         }
 440
 441         dump_irq = opal_event_request(ilog2(OPAL_EVENT_DUMP_AVAIL));
 442         if (!dump_irq) {
 443                 pr_err("%s: Can't register OPAL event irq (%d)\n",
 444                        __func__, dump_irq);
 445                 return;
 446         }
 447
 448         rc = request_threaded_irq(dump_irq, NULL, process_dump,
 449                                 IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
 450                                 "opal-dump", NULL);
 451         if (rc) {
 452                 pr_err("%s: Can't request OPAL event irq (%d)\n",
 453                        __func__, rc);
 454                 return;
 455         }
 456
 457         if (opal_check_token(OPAL_DUMP_RESEND))
 458                 opal_dump_resend_notification();
 459 }