[PATCH v8 1/4] efi_var_file: refactor to move buffer functions
Ilias Apalodimas
ilias.apalodimas at linaro.org
Thu Feb 12 07:14:22 CET 2026
On Wed, 11 Feb 2026 at 17:56, Michal Simek <michal.simek at amd.com> wrote:
>
> From: Shantur Rathore <i at shantur.com>
>
> Currently efi_var_file.c has functions to store/read
> EFI variables to/from memory buffer. These functions
> can be used with other EFI variable stores so move
> them out to efi_var_common.c
>
> Signed-off-by: Shantur Rathore <i at shantur.com>
> Signed-off-by: Michal Simek <michal.simek at amd.com>
> Tested-by: Neil Armstrong <neil.armstrong at linaro.org> # on AML-S905D3-CC
>
> ---
Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
>
> (no changes since v6)
>
> Changes in v6:
> - Return EFI_SUCCESS in efi_set_variable_int() when
> CONFIG_EFI_VARIABLE_NO_STORE is enabled
>
> Changes in v5:
> - Invert logic in efi_variable.c and avoid #if
>
> include/efi_variable.h | 5 +++
> lib/efi_loader/Makefile | 2 +-
> lib/efi_loader/efi_var_common.c | 42 ++++++++++++++++++++++++
> lib/efi_loader/efi_var_file.c | 57 ---------------------------------
> lib/efi_loader/efi_variable.c | 17 +++++++---
> 5 files changed, 60 insertions(+), 63 deletions(-)
>
> diff --git a/include/efi_variable.h b/include/efi_variable.h
> index 4065cf45ecaf..ee68fa4a885f 100644
> --- a/include/efi_variable.h
> +++ b/include/efi_variable.h
> @@ -161,6 +161,11 @@ efi_status_t efi_var_to_file(void);
> efi_status_t __maybe_unused efi_var_collect(struct efi_var_file **bufp, loff_t *lenp,
> u32 check_attr_mask);
>
> +/* GUID used by Shim to store the MOK database */
> +#define SHIM_LOCK_GUID \
> + EFI_GUID(0x605dab50, 0xe046, 0x4300, \
> + 0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23)
> +
> /**
> * efi_var_restore() - restore EFI variables from buffer
> *
> diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
> index f490081f6542..ca1775eb03be 100644
> --- a/lib/efi_loader/Makefile
> +++ b/lib/efi_loader/Makefile
> @@ -53,7 +53,7 @@ ifeq ($(CONFIG_EFI_MM_COMM_TEE),y)
> obj-y += efi_variable_tee.o
> else
> obj-y += efi_variable.o
> -obj-y += efi_var_file.o
> +obj-$(CONFIG_EFI_VARIABLE_FILE_STORE) += efi_var_file.o
> obj-$(CONFIG_EFI_VARIABLES_PRESEED) += efi_var_seed.o
> endif
> obj-y += efi_watchdog.o
> diff --git a/lib/efi_loader/efi_var_common.c b/lib/efi_loader/efi_var_common.c
> index 4b34a58b4cf7..5ea1688dca3d 100644
> --- a/lib/efi_loader/efi_var_common.c
> +++ b/lib/efi_loader/efi_var_common.c
> @@ -41,6 +41,7 @@ static const struct efi_auth_var_name_type name_type[] = {
>
> static bool efi_secure_boot;
> static enum efi_secure_mode efi_secure_mode;
> +static const efi_guid_t shim_lock_guid = SHIM_LOCK_GUID;
>
> /**
> * efi_efi_get_variable() - retrieve value of a UEFI variable
> @@ -488,3 +489,44 @@ efi_status_t __maybe_unused efi_var_collect(struct efi_var_file **bufp, loff_t *
>
> return EFI_SUCCESS;
> }
> +
> +efi_status_t efi_var_restore(struct efi_var_file *buf, bool safe)
> +{
> + struct efi_var_entry *var, *last_var;
> + u16 *data;
> + efi_status_t ret;
> +
> + if (buf->reserved || buf->magic != EFI_VAR_FILE_MAGIC ||
> + buf->crc32 != crc32(0, (u8 *)buf->var,
> + buf->length - sizeof(struct efi_var_file))) {
> + log_err("Invalid EFI variables file\n");
> + return EFI_INVALID_PARAMETER;
> + }
> +
> + last_var = (struct efi_var_entry *)((u8 *)buf + buf->length);
> + for (var = buf->var; var < last_var;
> + var = (struct efi_var_entry *)ALIGN((uintptr_t)data + var->length, 8)) {
> + data = var->name + u16_strlen(var->name) + 1;
> +
> + /*
> + * Secure boot related and volatile variables shall only be
> + * restored from U-Boot's preseed.
> + */
> + if (!safe &&
> + (efi_auth_var_get_type(var->name, &var->guid) !=
> + EFI_AUTH_VAR_NONE ||
> + !guidcmp(&var->guid, &shim_lock_guid) ||
> + !(var->attr & EFI_VARIABLE_NON_VOLATILE)))
> + continue;
> + if (!var->length)
> + continue;
> + if (efi_var_mem_find(&var->guid, var->name, NULL))
> + continue;
> + ret = efi_var_mem_ins(var->name, &var->guid, var->attr,
> + var->length, data, 0, NULL,
> + var->time);
> + if (ret != EFI_SUCCESS)
> + log_err("Failed to set EFI variable %ls\n", var->name);
> + }
> + return EFI_SUCCESS;
> +}
> diff --git a/lib/efi_loader/efi_var_file.c b/lib/efi_loader/efi_var_file.c
> index f23a964a4180..4061a463b580 100644
> --- a/lib/efi_loader/efi_var_file.c
> +++ b/lib/efi_loader/efi_var_file.c
> @@ -14,17 +14,9 @@
> #include <mapmem.h>
> #include <efi_loader.h>
> #include <efi_variable.h>
> -#include <u-boot/crc.h>
>
> #define PART_STR_LEN 10
>
> -/* GUID used by Shim to store the MOK database */
> -#define SHIM_LOCK_GUID \
> - EFI_GUID(0x605dab50, 0xe046, 0x4300, \
> - 0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23)
> -
> -static const efi_guid_t shim_lock_guid = SHIM_LOCK_GUID;
> -
> /**
> * efi_set_blk_dev_to_system_partition() - select EFI system partition
> *
> @@ -59,7 +51,6 @@ static efi_status_t __maybe_unused efi_set_blk_dev_to_system_partition(void)
> */
> efi_status_t efi_var_to_file(void)
> {
> -#ifdef CONFIG_EFI_VARIABLE_FILE_STORE
> efi_status_t ret;
> struct efi_var_file *buf;
> loff_t len;
> @@ -91,52 +82,6 @@ error:
> out:
> free(buf);
> return ret;
> -#else
> - return EFI_SUCCESS;
> -#endif
> -}
> -
> -efi_status_t efi_var_restore(struct efi_var_file *buf, bool safe)
> -{
> - struct efi_var_entry *var, *last_var;
> - u16 *data;
> - efi_status_t ret;
> -
> - if (buf->reserved || buf->magic != EFI_VAR_FILE_MAGIC ||
> - buf->crc32 != crc32(0, (u8 *)buf->var,
> - buf->length - sizeof(struct efi_var_file))) {
> - log_err("Invalid EFI variables file\n");
> - return EFI_INVALID_PARAMETER;
> - }
> -
> - last_var = (struct efi_var_entry *)((u8 *)buf + buf->length);
> - for (var = buf->var; var < last_var;
> - var = (struct efi_var_entry *)
> - ALIGN((uintptr_t)data + var->length, 8)) {
> -
> - data = var->name + u16_strlen(var->name) + 1;
> -
> - /*
> - * Secure boot related and volatile variables shall only be
> - * restored from U-Boot's preseed.
> - */
> - if (!safe &&
> - (efi_auth_var_get_type(var->name, &var->guid) !=
> - EFI_AUTH_VAR_NONE ||
> - !guidcmp(&var->guid, &shim_lock_guid) ||
> - !(var->attr & EFI_VARIABLE_NON_VOLATILE)))
> - continue;
> - if (!var->length)
> - continue;
> - if (efi_var_mem_find(&var->guid, var->name, NULL))
> - continue;
> - ret = efi_var_mem_ins(var->name, &var->guid, var->attr,
> - var->length, data, 0, NULL,
> - var->time);
> - if (ret != EFI_SUCCESS)
> - log_err("Failed to set EFI variable %ls\n", var->name);
> - }
> - return EFI_SUCCESS;
> }
>
> /**
> @@ -155,7 +100,6 @@ efi_status_t efi_var_restore(struct efi_var_file *buf, bool safe)
> */
> efi_status_t efi_var_from_file(void)
> {
> -#ifdef CONFIG_EFI_VARIABLE_FILE_STORE
> struct efi_var_file *buf;
> loff_t len;
> efi_status_t ret;
> @@ -180,6 +124,5 @@ efi_status_t efi_var_from_file(void)
> log_err("Invalid EFI variables file\n");
> error:
> free(buf);
> -#endif
> return EFI_SUCCESS;
> }
> diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
> index f3533f4def3a..6e45134c61bf 100644
> --- a/lib/efi_loader/efi_variable.c
> +++ b/lib/efi_loader/efi_variable.c
> @@ -397,11 +397,15 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
> ret = EFI_SUCCESS;
>
> /*
> - * Write non-volatile EFI variables to file
> + * Write non-volatile EFI variables
> * TODO: check if a value change has occured to avoid superfluous writes
> */
> - if (attributes & EFI_VARIABLE_NON_VOLATILE)
> + if (attributes & EFI_VARIABLE_NON_VOLATILE) {
> + if (IS_ENABLED(CONFIG_EFI_VARIABLE_NO_STORE))
> + return EFI_SUCCESS;
> +
> efi_var_to_file();
> + }
>
> return EFI_SUCCESS;
> }
> @@ -594,9 +598,12 @@ efi_status_t efi_init_variables(void)
> if (ret != EFI_SUCCESS)
> return ret;
>
> - ret = efi_var_from_file();
> - if (ret != EFI_SUCCESS)
> - return ret;
> + if (!IS_ENABLED(CONFIG_EFI_VARIABLE_NO_STORE)) {
> + ret = efi_var_from_file();
> + if (ret != EFI_SUCCESS)
> + return ret;
> + }
> +
> if (IS_ENABLED(CONFIG_EFI_VARIABLES_PRESEED)) {
> ret = efi_var_restore((struct efi_var_file *)
> __efi_var_file_begin, true);
> --
> 2.43.0
>
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