[PATCH] efi_loader: remove comparisons to string literals from runtime

[Mark Kettenis]

> From: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> Date: Fri, 14 Feb 2025 15:46:45 +0200
> 
> For EFI runtime services, we manage to preserve string literals
> by placing the .efi_runtime section just before .data and preserving
> it when marking the runtime memory by marking surrounding boottime
> code as runtime. This is ok for now but will break if we update any
> linker scripts and decouple .text and .runtime sections.
> 
> So let's define the strings we used to compare in the appropriate
> section for runtime services
> 
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> ---
>  lib/efi_loader/efi_var_mem.c      | 3 ++-
>  lib/efi_loader/efi_variable_tee.c | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)

Yes, that looks much better.

Reviewed-by: Mark Kettenis <kettenis at openbsd.org>

> diff --git a/lib/efi_loader/efi_var_mem.c b/lib/efi_loader/efi_var_mem.c
> index b265d95dd6ba..31180df9e3a0 100644
> --- a/lib/efi_loader/efi_var_mem.c
> +++ b/lib/efi_loader/efi_var_mem.c
> @@ -19,6 +19,7 @@
>   */
>  static struct efi_var_file __efi_runtime_data *efi_var_buf;
>  static struct efi_var_entry __efi_runtime_data *efi_current_var;
> +static const u16 __efi_runtime_rodata vtf[] = u"VarToFile";
>  
>  /**
>   * efi_var_mem_compare() - compare GUID and name with a variable
> @@ -331,7 +332,7 @@ efi_get_variable_mem(const u16 *variable_name, const efi_guid_t *vendor,
>  	if (timep)
>  		*timep = var->time;
>  
> -	if (!u16_strcmp(variable_name, u"VarToFile"))
> +	if (!u16_strcmp(variable_name, vtf))
>  		return efi_var_collect_mem(data, data_size, EFI_VARIABLE_NON_VOLATILE);
>  
>  	old_size = *data_size;
> diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
> index 0d090d051dd4..6a1fa39bb6f3 100644
> --- a/lib/efi_loader/efi_variable_tee.c
> +++ b/lib/efi_loader/efi_variable_tee.c
> @@ -41,6 +41,7 @@ static u16 mm_sp_id;
>  extern struct efi_var_file __efi_runtime_data *efi_var_buf;
>  static efi_uintn_t max_buffer_size;	/* comm + var + func + data */
>  static efi_uintn_t max_payload_size;	/* func + data */
> +static const u16 __efi_runtime_rodata pk[] = u"PK";
>  
>  struct mm_connection {
>  	struct udevice *tee;
> @@ -858,7 +859,7 @@ efi_status_t efi_set_variable_int(const u16 *variable_name,
>  	if (alt_ret != EFI_SUCCESS)
>  		goto out;
>  
> -	if (!u16_strcmp(variable_name, u"PK"))
> +	if (!u16_strcmp(variable_name, pk))
>  		alt_ret = efi_init_secure_state();
>  out:
>  	free(comm_buf);
> -- 
> 2.47.2
> 
>