drivers/firmware/efi/efi-pstore.c

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