Re: [PATCH v2 2/3] efi_loader: carve out efi_get_memory_map_alloc()

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

On Thu, Jan 05, 2023 at 09:25:35PM +0100, Heinrich Schuchardt wrote:
> Carve out code from efidebug command used to read the memory map.
> 
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
> ---
> v2:
> 	new patch
> ---
>  cmd/efidebug.c              | 18 ++++--------------
>  include/efi_loader.h        |  3 +++
>  lib/efi_loader/efi_memory.c | 34 ++++++++++++++++++++++++++++++++++
>  3 files changed, 41 insertions(+), 14 deletions(-)
> 
> diff --git a/cmd/efidebug.c b/cmd/efidebug.c
> index 569003ae2e..e6959ede93 100644
> --- a/cmd/efidebug.c
> +++ b/cmd/efidebug.c
> @@ -591,25 +591,15 @@ static void print_memory_attributes(u64 attributes)
>  static int do_efi_show_memmap(struct cmd_tbl *cmdtp, int flag,
>  			      int argc, char *const argv[])
>  {
> -	struct efi_mem_desc *memmap = NULL, *map;
> -	efi_uintn_t map_size = 0;
> +	struct efi_mem_desc *memmap, *map;
> +	efi_uintn_t map_size;
>  	const char *type;
>  	int i;
>  	efi_status_t ret;
>  
> -	ret = efi_get_memory_map(&map_size, memmap, NULL, NULL, NULL);
> -	if (ret == EFI_BUFFER_TOO_SMALL) {
> -		map_size += sizeof(struct efi_mem_desc); /* for my own */
> -		ret = efi_allocate_pool(EFI_BOOT_SERVICES_DATA, map_size,
> -					(void *)&memmap);
> -		if (ret != EFI_SUCCESS)
> -			return CMD_RET_FAILURE;
> -		ret = efi_get_memory_map(&map_size, memmap, NULL, NULL, NULL);
> -	}
> -	if (ret != EFI_SUCCESS) {
> -		efi_free_pool(memmap);
> +	ret = efi_get_memory_map_alloc(&map_size, &memmap);
> +	if (ret != EFI_SUCCESS)
>  		return CMD_RET_FAILURE;
> -	}
>  
>  	printf("Type             Start%.*s End%.*s Attributes\n",
>  	       EFI_PHYS_ADDR_WIDTH - 5, spc, EFI_PHYS_ADDR_WIDTH - 3, spc);
> diff --git a/include/efi_loader.h b/include/efi_loader.h
> index 0899e293e5..02d151b715 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -734,6 +734,9 @@ efi_status_t efi_allocate_pool(enum efi_memory_type pool_type,
>  			       efi_uintn_t size, void **buffer);
>  /* EFI pool memory free function. */
>  efi_status_t efi_free_pool(void *buffer);
> +/* Allocate and retrieve EFI memory map */
> +efi_status_t efi_get_memory_map_alloc(efi_uintn_t *map_size,
> +				      struct efi_mem_desc **memory_map);
>  /* Returns the EFI memory map */
>  efi_status_t efi_get_memory_map(efi_uintn_t *memory_map_size,
>  				struct efi_mem_desc *memory_map,
> diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
> index 8d347f101f..32254d2433 100644
> --- a/lib/efi_loader/efi_memory.c
> +++ b/lib/efi_loader/efi_memory.c
> @@ -736,6 +736,40 @@ efi_status_t efi_get_memory_map(efi_uintn_t *memory_map_size,
>  	return EFI_SUCCESS;
>  }
>  
> +/**
> + * efi_get_memory_map_alloc() - allocate map describing memory usage
> + *
> + * The caller is responsible for calling FreePool() if the call succeeds.
> + *
> + * @memory_map		buffer to which the memory map is written
> + * @map_size		size of the memory map
> + * Return:		status code
> + */
> +efi_status_t efi_get_memory_map_alloc(efi_uintn_t *map_size,
> +				      struct efi_mem_desc **memory_map)
> +{
> +	efi_status_t ret;
> +
> +	*memory_map = NULL;
> +	*map_size = 0;
> +	ret = efi_get_memory_map(map_size, *memory_map, NULL, NULL, NULL);

Although this is correct and efi_get_memory_map() will only return
EFI_BUFFER_TOO_SMALL, since we initialize the map_size to 0,  I don't know
if code analysis tools are smart enough to understand this.  Perhaps we
should initialize ret?


> +	if (ret == EFI_BUFFER_TOO_SMALL) {
> +		*map_size += sizeof(struct efi_mem_desc); /* for the map */
> +		ret = efi_allocate_pool(EFI_BOOT_SERVICES_DATA, *map_size,
> +					(void **)memory_map);
> +		if (ret != EFI_SUCCESS)
> +			return ret;
> +		ret = efi_get_memory_map(map_size, *memory_map,
> +					 NULL, NULL, NULL);
> +		if (ret != EFI_SUCCESS) {
> +			efi_free_pool(*memory_map);
> +			*memory_map = NULL;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
>  /**
>   * efi_add_conventional_memory_map() - add a RAM memory area to the map
>   *
> -- 
> 2.37.2
> 

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