[PATCH v3 3/4] lib: efi_loader: efi_memory.c: add efi_realloc() for realloc memory

[Simon Glass]

Hi,

On Thu, 22 May 2025 at 03:18, Ying-Chun Liu (PaulLiu)
<paulliu at debian.org> wrote:
>
> From: "Ying-Chun Liu (PaulLiu)" <paul.liu at linaro.org>
>
> Add efi_realloc() for realloc memory that previously alloc by efi_alloc().
>
> Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu at linaro.org>
> Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
> Cc: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> Cc: Peter Robinson <pbrobinson at gmail.com>
> ---
>  include/efi_loader.h        |  2 ++
>  lib/efi_loader/efi_memory.c | 52 +++++++++++++++++++++++++++++++++++++
>  2 files changed, 54 insertions(+)
>
> diff --git a/include/efi_loader.h b/include/efi_loader.h
> index d0c72d0bc58..ff7ca5a0480 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -878,6 +878,8 @@ efi_status_t efi_next_variable_name(efi_uintn_t *size, u16 **buf,
>  #define efi_size_in_pages(size) (((size) + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT)
>  /* Allocate boot service data pool memory */
>  void *efi_alloc(size_t len);
> +/* Reallocate boot service data pool memory */
> +void *efi_realloc(void *ptr, size_t len);
>  /* Allocate pages on the specified alignment */
>  void *efi_alloc_aligned_pages(u64 len, int memory_type, size_t align);
>  /* More specific EFI memory allocator, called by EFI payloads */
> diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
> index 0abb1f6159a..4c76df642dc 100644
> --- a/lib/efi_loader/efi_memory.c
> +++ b/lib/efi_loader/efi_memory.c
> @@ -666,6 +666,58 @@ void *efi_alloc(size_t size)
>         return buf;
>  }
>
> +/**
> + * efi_realloc() - reallocate boot services data pool memory
> + *
> + * Reallocate memory from pool for a new size and copy the data from old one.
> + *
> + * @ptr:       pointer to old buffer
> + * @size:      number of bytes to allocate
> + * Return:     pointer to allocated memory or NULL
> + */

Should go in header file

> +void *efi_realloc(void *ptr, size_t size)
> +{
> +       efi_status_t ret;
> +       void *new_ptr;
> +       struct efi_pool_allocation *alloc;
> +       u64 num_pages = efi_size_in_pages(size +
> +                                         sizeof(struct efi_pool_allocation));
> +       size_t old_size;
> +
> +       if (!ptr)
> +               return efi_alloc(size);
> +
> +       ret = efi_check_allocated((uintptr_t)ptr, true);
> +       if (ret != EFI_SUCCESS)
> +               return ptr;
> +
> +       alloc = container_of(ptr, struct efi_pool_allocation, data);
> +
> +       /* Check that this memory was allocated by efi_allocate_pool() */
> +       if (((uintptr_t)alloc & EFI_PAGE_MASK) ||
> +           alloc->checksum != checksum(alloc)) {
> +               printf("%s: illegal realloc 0x%p\n", __func__, ptr);
> +               return ptr;
> +       }
> +
> +       /* Don't realloc. The actual size in pages is the same. */
> +       if (alloc->num_pages == num_pages)
> +               return ptr;
> +
> +       old_size = alloc->num_pages * EFI_PAGE_SIZE -
> +               sizeof(struct efi_pool_allocation);
> +
> +       new_ptr = efi_alloc(size);
> +
> +       /* copy old data to new alloced buffer */
> +       memcpy(new_ptr, ptr, min(size, old_size));
> +
> +       /* free the old buffer */
> +       efi_free_pool(ptr);
> +
> +       return new_ptr;
> +}
> +
>  /**
>   * efi_free_pool() - free memory from pool
>   *
> --
> 2.39.5
>

Could you add a bit of detail as to why this patch is needed? It is
hard to tell which code will actually use it. So long as it cannot be
used outside lib/efi_loader then it should be OK.

I would like to remove most/all use of efi_alloc() so that the EFI app
can use the standard U-Boot malloc(). I am not 100% sure about this,
but so far it seems like the best way to support EFI booting from the
EFI app.

So if this patch is accepted, it may make it harder to reconcile
memory allocation in U-Boot across EFI loader and app.

Regards,
Simon