drivers/firmware/efi/efi-pstore.c

   1 #include <linux/efi.h>
   2 #include <linux/module.h>
   3 #include <linux/pstore.h>
   4 #include <linux/slab.h>
   5 #include <linux/ucs2_string.h>
   6
   7 #define DUMP_NAME_LEN 52
   8
   9 static bool efivars_pstore_disable =
  10         IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);
  11
  12 module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);
  13
  14 #define PSTORE_EFI_ATTRIBUTES \
  15         (EFI_VARIABLE_NON_VOLATILE | \
  16          EFI_VARIABLE_BOOTSERVICE_ACCESS | \
  17          EFI_VARIABLE_RUNTIME_ACCESS)
  18
  19 static int efi_pstore_open(struct pstore_info *psi)
  20 {
  21         efivar_entry_iter_begin();
  22         psi->data = NULL;
  23         return 0;
  24 }
  25
  26 static int efi_pstore_close(struct pstore_info *psi)
  27 {
  28         efivar_entry_iter_end();
  29         psi->data = NULL;
  30         return 0;
  31 }
  32
  33 struct pstore_read_data {
  34         u64 *id;
  35         enum pstore_type_id *type;
  36         int *count;
  37         struct timespec *timespec;
  38         char **buf;
  39 };
  40
  41 static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
  42 {
  43         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
  44         struct pstore_read_data *cb_data = data;
  45         char name[DUMP_NAME_LEN];
  46         int i;
  47         int cnt;
  48         unsigned int part;
  49         unsigned long time, size;
  50
  51         if (efi_guidcmp(entry->var.VendorGuid, vendor))
  52                 return 0;
  53
  54         for (i = 0; i < DUMP_NAME_LEN; i++)
  55                 name[i] = entry->var.VariableName[i];
  56
  57         if (sscanf(name, "dump-type%u-%u-%d-%lu",
  58                    cb_data->type, &part, &cnt, &time) == 4) {
  59                 *cb_data->id = part;
  60                 *cb_data->count = cnt;
  61                 cb_data->timespec->tv_sec = time;
  62                 cb_data->timespec->tv_nsec = 0;
  63         } else if (sscanf(name, "dump-type%u-%u-%lu",
  64                           cb_data->type, &part, &time) == 3) {
  65                 /*
  66                  * Check if an old format,
  67                  * which doesn't support holding
  68                  * multiple logs, remains.
  69                  */
  70                 *cb_data->id = part;
  71                 *cb_data->count = 0;
  72                 cb_data->timespec->tv_sec = time;
  73                 cb_data->timespec->tv_nsec = 0;
  74         } else
  75                 return 0;
  76
  77         entry->var.DataSize = 1024;
  78         __efivar_entry_get(entry, &entry->var.Attributes,
  79                            &entry->var.DataSize, entry->var.Data);
  80         size = entry->var.DataSize;
  81
  82         *cb_data->buf = kmalloc(size, GFP_KERNEL);
  83         if (*cb_data->buf == NULL)
  84                 return -ENOMEM;
  85         memcpy(*cb_data->buf, entry->var.Data, size);
  86         return size;
  87 }
  88
  89 static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
  90                                int *count, struct timespec *timespec,
  91                                char **buf, struct pstore_info *psi)
  92 {
  93         struct pstore_read_data data;
  94
  95         data.id = id;
  96         data.type = type;
  97         data.count = count;
  98         data.timespec = timespec;
  99         data.buf = buf;
 100
 101         return __efivar_entry_iter(efi_pstore_read_func, &efivar_sysfs_list, &data,
 102                                    (struct efivar_entry **)&psi->data);
 103 }
 104
 105 static int efi_pstore_write(enum pstore_type_id type,
 106                 enum kmsg_dump_reason reason, u64 *id,
 107                 unsigned int part, int count, size_t size,
 108                 struct pstore_info *psi)
 109 {
 110         char name[DUMP_NAME_LEN];
 111         efi_char16_t efi_name[DUMP_NAME_LEN];
 112         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 113         int i, ret = 0;
 114
 115         sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count,
 116                 get_seconds());
 117
 118         for (i = 0; i < DUMP_NAME_LEN; i++)
 119                 efi_name[i] = name[i];
 120
 121         efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
 122                               !pstore_cannot_block_path(reason),
 123                               size, psi->buf);
 124
 125         if (reason == KMSG_DUMP_OOPS)
 126                 efivar_run_worker();
 127
 128         *id = part;
 129         return ret;
 130 };
 131
 132 struct pstore_erase_data {
 133         u64 id;
 134         enum pstore_type_id type;
 135         int count;
 136         struct timespec time;
 137         efi_char16_t *name;
 138 };
 139
 140 /*
 141  * Clean up an entry with the same name
 142  */
 143 static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
 144 {
 145         struct pstore_erase_data *ed = data;
 146         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 147         efi_char16_t efi_name_old[DUMP_NAME_LEN];
 148         efi_char16_t *efi_name = ed->name;
 149         unsigned long ucs2_len = ucs2_strlen(ed->name);
 150         char name_old[DUMP_NAME_LEN];
 151         int i;
 152
 153         if (efi_guidcmp(entry->var.VendorGuid, vendor))
 154                 return 0;
 155
 156         if (ucs2_strncmp(entry->var.VariableName,
 157                           efi_name, (size_t)ucs2_len)) {
 158                 /*
 159                  * Check if an old format, which doesn't support
 160                  * holding multiple logs, remains.
 161                  */
 162                 sprintf(name_old, "dump-type%u-%u-%lu", ed->type,
 163                         (unsigned int)ed->id, ed->time.tv_sec);
 164
 165                 for (i = 0; i < DUMP_NAME_LEN; i++)
 166                         efi_name_old[i] = name_old[i];
 167
 168                 if (ucs2_strncmp(entry->var.VariableName, efi_name_old,
 169                                   ucs2_strlen(efi_name_old)))
 170                         return 0;
 171         }
 172
 173         /* found */
 174         __efivar_entry_delete(entry);
 175         list_del(&entry->list);
 176
 177         return 1;
 178 }
 179
 180 static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 181                             struct timespec time, struct pstore_info *psi)
 182 {
 183         struct pstore_erase_data edata;
 184         struct efivar_entry *entry = NULL;
 185         char name[DUMP_NAME_LEN];
 186         efi_char16_t efi_name[DUMP_NAME_LEN];
 187         int found, i;
 188
 189         sprintf(name, "dump-type%u-%u-%d-%lu", type, (unsigned int)id, count,
 190                 time.tv_sec);
 191
 192         for (i = 0; i < DUMP_NAME_LEN; i++)
 193                 efi_name[i] = name[i];
 194
 195         edata.id = id;
 196         edata.type = type;
 197         edata.count = count;
 198         edata.time = time;
 199         edata.name = efi_name;
 200
 201         efivar_entry_iter_begin();
 202         found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry);
 203         efivar_entry_iter_end();
 204
 205         if (found)
 206                 efivar_unregister(entry);
 207
 208         return 0;
 209 }
 210
 211 static struct pstore_info efi_pstore_info = {
 212         .owner          = THIS_MODULE,
 213         .name           = "efi",
 214         .open           = efi_pstore_open,
 215         .close          = efi_pstore_close,
 216         .read           = efi_pstore_read,
 217         .write          = efi_pstore_write,
 218         .erase          = efi_pstore_erase,
 219 };
 220
 221 static __init int efivars_pstore_init(void)
 222 {
 223         if (!efi_enabled(EFI_RUNTIME_SERVICES))
 224                 return 0;
 225
 226         if (!efivars_kobject())
 227                 return 0;
 228
 229         if (efivars_pstore_disable)
 230                 return 0;
 231
 232         efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
 233         if (!efi_pstore_info.buf)
 234                 return -ENOMEM;
 235
 236         efi_pstore_info.bufsize = 1024;
 237         spin_lock_init(&efi_pstore_info.buf_lock);
 238
 239         pstore_register(&efi_pstore_info);
 240
 241         return 0;
 242 }
 243
 244 static __exit void efivars_pstore_exit(void)
 245 {
 246 }
 247
 248 module_init(efivars_pstore_init);
 249 module_exit(efivars_pstore_exit);
 250
 251 MODULE_DESCRIPTION("EFI variable backend for pstore");
 252 MODULE_LICENSE("GPL");