diff options
Diffstat (limited to 'drivers/firmware/efi/efi-pstore.c')
| -rw-r--r-- | drivers/firmware/efi/efi-pstore.c | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c new file mode 100644 index 000000000..3bddc152f --- /dev/null +++ b/drivers/firmware/efi/efi-pstore.c @@ -0,0 +1,258 @@ +// SPDX-License-Identifier: GPL-2.0+ + +#include <linux/efi.h> +#include <linux/module.h> +#include <linux/pstore.h> +#include <linux/slab.h> +#include <linux/ucs2_string.h> + +MODULE_IMPORT_NS(EFIVAR); + +#define DUMP_NAME_LEN 66 + +#define EFIVARS_DATA_SIZE_MAX 1024 + +static bool efivars_pstore_disable = + IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE); + +module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644); + +#define PSTORE_EFI_ATTRIBUTES \ + (EFI_VARIABLE_NON_VOLATILE | \ + EFI_VARIABLE_BOOTSERVICE_ACCESS | \ + EFI_VARIABLE_RUNTIME_ACCESS) + +static int efi_pstore_open(struct pstore_info *psi) +{ + int err; + + err = efivar_lock(); + if (err) + return err; + + psi->data = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL); + if (!psi->data) + return -ENOMEM; + + return 0; +} + +static int efi_pstore_close(struct pstore_info *psi) +{ + efivar_unlock(); + kfree(psi->data); + return 0; +} + +static inline u64 generic_id(u64 timestamp, unsigned int part, int count) +{ + return (timestamp * 100 + part) * 1000 + count; +} + +static int efi_pstore_read_func(struct pstore_record *record, + efi_char16_t *varname) +{ + unsigned long wlen, size = EFIVARS_DATA_SIZE_MAX; + char name[DUMP_NAME_LEN], data_type; + efi_status_t status; + int cnt; + unsigned int part; + u64 time; + + ucs2_as_utf8(name, varname, DUMP_NAME_LEN); + + if (sscanf(name, "dump-type%u-%u-%d-%llu-%c", + &record->type, &part, &cnt, &time, &data_type) == 5) { + record->id = generic_id(time, part, cnt); + record->part = part; + record->count = cnt; + record->time.tv_sec = time; + record->time.tv_nsec = 0; + if (data_type == 'C') + record->compressed = true; + else + record->compressed = false; + record->ecc_notice_size = 0; + } else if (sscanf(name, "dump-type%u-%u-%d-%llu", + &record->type, &part, &cnt, &time) == 4) { + record->id = generic_id(time, part, cnt); + record->part = part; + record->count = cnt; + record->time.tv_sec = time; + record->time.tv_nsec = 0; + record->compressed = false; + record->ecc_notice_size = 0; + } else if (sscanf(name, "dump-type%u-%u-%llu", + &record->type, &part, &time) == 3) { + /* + * Check if an old format, + * which doesn't support holding + * multiple logs, remains. + */ + record->id = generic_id(time, part, 0); + record->part = part; + record->count = 0; + record->time.tv_sec = time; + record->time.tv_nsec = 0; + record->compressed = false; + record->ecc_notice_size = 0; + } else + return 0; + + record->buf = kmalloc(size, GFP_KERNEL); + if (!record->buf) + return -ENOMEM; + + status = efivar_get_variable(varname, &LINUX_EFI_CRASH_GUID, NULL, + &size, record->buf); + if (status != EFI_SUCCESS) { + kfree(record->buf); + return -EIO; + } + + /* + * Store the name of the variable in the pstore_record priv field, so + * we can reuse it later if we need to delete the EFI variable from the + * variable store. + */ + wlen = (ucs2_strnlen(varname, DUMP_NAME_LEN) + 1) * sizeof(efi_char16_t); + record->priv = kmemdup(varname, wlen, GFP_KERNEL); + if (!record->priv) { + kfree(record->buf); + return -ENOMEM; + } + + return size; +} + +static ssize_t efi_pstore_read(struct pstore_record *record) +{ + efi_char16_t *varname = record->psi->data; + efi_guid_t guid = LINUX_EFI_CRASH_GUID; + unsigned long varname_size; + efi_status_t status; + + for (;;) { + varname_size = EFIVARS_DATA_SIZE_MAX; + + /* + * If this is the first read() call in the pstore enumeration, + * varname will be the empty string, and the GetNextVariable() + * runtime service call will return the first EFI variable in + * its own enumeration order, ignoring the guid argument. + * + * Subsequent calls to GetNextVariable() must pass the name and + * guid values returned by the previous call, which is why we + * store varname in record->psi->data. Given that we only + * enumerate variables with the efi-pstore GUID, there is no + * need to record the guid return value. + */ + status = efivar_get_next_variable(&varname_size, varname, &guid); + if (status == EFI_NOT_FOUND) + return 0; + + if (status != EFI_SUCCESS) + return -EIO; + + /* skip variables that don't concern us */ + if (efi_guidcmp(guid, LINUX_EFI_CRASH_GUID)) + continue; + + return efi_pstore_read_func(record, varname); + } +} + +static int efi_pstore_write(struct pstore_record *record) +{ + char name[DUMP_NAME_LEN]; + efi_char16_t efi_name[DUMP_NAME_LEN]; + efi_status_t status; + int i; + + record->id = generic_id(record->time.tv_sec, record->part, + record->count); + + /* Since we copy the entire length of name, make sure it is wiped. */ + memset(name, 0, sizeof(name)); + + snprintf(name, sizeof(name), "dump-type%u-%u-%d-%lld-%c", + record->type, record->part, record->count, + (long long)record->time.tv_sec, + record->compressed ? 'C' : 'D'); + + for (i = 0; i < DUMP_NAME_LEN; i++) + efi_name[i] = name[i]; + + if (efivar_trylock()) + return -EBUSY; + status = efivar_set_variable_locked(efi_name, &LINUX_EFI_CRASH_GUID, + PSTORE_EFI_ATTRIBUTES, + record->size, record->psi->buf, + true); + efivar_unlock(); + return status == EFI_SUCCESS ? 0 : -EIO; +}; + +static int efi_pstore_erase(struct pstore_record *record) +{ + efi_status_t status; + + status = efivar_set_variable(record->priv, &LINUX_EFI_CRASH_GUID, + PSTORE_EFI_ATTRIBUTES, 0, NULL); + + if (status != EFI_SUCCESS && status != EFI_NOT_FOUND) + return -EIO; + return 0; +} + +static struct pstore_info efi_pstore_info = { + .owner = THIS_MODULE, + .name = "efi", + .flags = PSTORE_FLAGS_DMESG, + .open = efi_pstore_open, + .close = efi_pstore_close, + .read = efi_pstore_read, + .write = efi_pstore_write, + .erase = efi_pstore_erase, +}; + +static __init int efivars_pstore_init(void) +{ + if (!efivar_supports_writes()) + return 0; + + if (efivars_pstore_disable) + return 0; + + efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL); + if (!efi_pstore_info.buf) + return -ENOMEM; + + efi_pstore_info.bufsize = 1024; + + if (pstore_register(&efi_pstore_info)) { + kfree(efi_pstore_info.buf); + efi_pstore_info.buf = NULL; + efi_pstore_info.bufsize = 0; + } + + return 0; +} + +static __exit void efivars_pstore_exit(void) +{ + if (!efi_pstore_info.bufsize) + return; + + pstore_unregister(&efi_pstore_info); + kfree(efi_pstore_info.buf); + efi_pstore_info.buf = NULL; + efi_pstore_info.bufsize = 0; +} + +module_init(efivars_pstore_init); +module_exit(efivars_pstore_exit); + +MODULE_DESCRIPTION("EFI variable backend for pstore"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:efivars"); |