[PATCH 01/12] efi_loader: add runtime memset helper

[Ilias Apalodimas]

On Fri, 24 Apr 2026 at 20:32, Harsimran Singh Tungal
<harsimransingh.tungal at arm.com> wrote:
>
> Add efi_memset_runtime() for EFI runtime paths
>
> This keeps buffer initialization in runtime-resident code after
> ExitBootServices() and avoids relying on non-runtime helpers.
>
> Signed-off-by: Harsimran Singh Tungal <harsimransingh.tungal at arm.com>
> ---

Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>

>  include/efi_loader.h         |  3 +++
>  lib/efi_loader/efi_runtime.c | 21 +++++++++++++++++++++
>  2 files changed, 24 insertions(+)
>
> diff --git a/include/efi_loader.h b/include/efi_loader.h
> index 3a4d502631c..63944192aeb 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -1151,6 +1151,9 @@ void efi_memcpy_runtime(void *dest, const void *src, size_t n);
>  /* runtime implementation of memcmp() */
>  int efi_memcmp_runtime(const void *s1, const void *s2, size_t n);
>
> +/* runtime implementation of memset */
> +__efi_runtime void *efi_memset_runtime(void *dest, int c, size_t n);
> +
>  /* commonly used helper functions */
>  u16 *efi_create_indexed_name(u16 *buffer, size_t buffer_size, const char *name,
>                              unsigned int index);
> diff --git a/lib/efi_loader/efi_runtime.c b/lib/efi_loader/efi_runtime.c
> index 73d4097464c..d9604399209 100644
> --- a/lib/efi_loader/efi_runtime.c
> +++ b/lib/efi_loader/efi_runtime.c
> @@ -233,6 +233,27 @@ int __efi_runtime efi_memcmp_runtime(const void *s1, const void *s2, size_t n)
>         return 0;
>  }
>
> +/**
> + * efi_memset_runtime() - fill a memory region with a byte value
> + *
> + * At runtime memset() is not available.
> + *
> + * @dest:   pointer to the block of memory to fill.
> + * @c:      value to be set. The value is passed as an int, but the
> + *          function fills the block of memory using the u8 conversion of this value.
> + * @n:      number of bytes to be set to the value.
> + * Return:  dest is returned
> + */
> +__efi_runtime void *efi_memset_runtime(void *dest, int c, size_t n)
> +{
> +       u8 *d = dest;
> +
> +       for (; n; --n)
> +               *d++ = c;
> +
> +       return dest;
> +}
> +
>  /**
>   * efi_update_table_header_crc32() - Update crc32 in table header
>   *
> --
> 2.34.1
>