[PATCH v2] cmd: bootefi: restore ability to boot arbitrary blob

[AKASHI Takahiro]

I thought I had sent out my comment when this patch was submitted first time,
but it seems that it has never reached out to ML.

On Sun, Apr 10, 2022 at 04:05:55PM -0500, kevans at FreeBSD.org wrote:
> From: Kyle Evans <kevans at FreeBSD.org>
> 
> Up until commit 5f59518a7b1ae ("efi_loader: setting boot device"), we
> could boot an arbitrary blob with bootefi.  Indeed, efi_run_image() even
> has a special case for missing device paths indicating a payload that
> was directly loaded via JTAG, for example.
> 
> Restore the ability to inject a UEFI payload into memory and `bootefi`
> it.  If the address passed isn't the last PE-COFF loaded, then we'll
> wipe out the pre-existing DP/Image information and let efi_run_image()
> synthesize a memory device path.
> 
> An image size is required if we're booting an arbitrary payload, and
> the FDT argument has been changed to accept `-`.  The size could be
> deduced from the image header, but it's required anyways as an explicit
> acknowledgment that one's trying to boot an arbitrary payload rather
> than accidentally using the wrong address in the single-addr form.

The syntax seems to be odd and I don't think it is user-friendly
   	"<image address> [fdt address [image size]]\n"
as an image-related parameter,<image size>, doesn't follow <address>
immediately but comes *after* <fdt address>.

Instead, I would suggest
    bootefi <image addr>[:<image size>] [<fdt addr>]
    (or     [<image size>@]<image addr>)

I believe that "<addr>:<size>" notation is quite intuitive and non-misleading.
Moreover, a similar syntax can be seen, for example, in booti command.

-Takahiro Akashi

> If the image address matches the last loaded PE_COFF, it is an error
> to pass the incorrect size (but the size may be omitted).
> 
> Signed-off-by: Kyle Evans <kevans at FreeBSD.org>
> ---
> 
> Changes since v1:
>  - Specifying an address that isn't the last-known without a size produces the
>     same error as in the past ("No UEFI binary known at ...")
>  - Specifying a size with the last known address that doesn't match the last
>     recorded size will get: Size does not match known UEFI binary at %s
> 
>  cmd/bootefi.c | 42 ++++++++++++++++++++++++++++++++++--------
>  1 file changed, 34 insertions(+), 8 deletions(-)
> 
> diff --git a/cmd/bootefi.c b/cmd/bootefi.c
> index 53d9f0e0dc..0d3aecb2a1 100644
> --- a/cmd/bootefi.c
> +++ b/cmd/bootefi.c
> @@ -425,7 +425,7 @@ static int do_efibootmgr(void)
>   * @image_opt:	string of image start address
>   * Return:	status code
>   */
> -static int do_bootefi_image(const char *image_opt)
> +static int do_bootefi_image(const char *image_opt, const char *size_opt)
>  {
>  	void *image_buf;
>  	unsigned long addr, size;
> @@ -444,13 +444,35 @@ static int do_bootefi_image(const char *image_opt)
>  		if (!addr)
>  			return CMD_RET_USAGE;
>  
> +		size = 0;
> +		if (size_opt) {
> +			size = strtoul(size_opt, NULL, 16);
> +			/* Check that a numeric value was passed */
> +			if (!size)
> +				return CMD_RET_USAGE;
> +		}
> +
>  		image_buf = map_sysmem(addr, 0);
>  
>  		if (image_buf != image_addr) {
> -			log_err("No UEFI binary known at %s\n", image_opt);
> -			return CMD_RET_FAILURE;
> +			/* Fake device path -- we must have a size. */
> +
> +			if (size == 0) {
> +				printf("No UEFI binary known at %s\n", image_opt);
> +				return CMD_RET_FAILURE;
> +			}
> +
> +			if (image_addr)
> +				efi_clear_bootdev();
> +		} else {
> +			if (size != 0 && size != image_size) {
> +				printf("Size does not match known UEFI binary at %s\n",
> +				       image_opt);
> +				return CMD_RET_FAILURE;
> +			}
> +
> +			size = image_size;
>  		}
> -		size = image_size;
>  	}
>  	ret = efi_run_image(image_buf, size);
>  
> @@ -654,7 +676,7 @@ static int do_bootefi(struct cmd_tbl *cmdtp, int flag, int argc,
>  		return CMD_RET_FAILURE;
>  	}
>  
> -	if (argc > 2) {
> +	if (argc > 2 && strcmp(argv[2], "-") != 0) {
>  		uintptr_t fdt_addr;
>  
>  		fdt_addr = hextoul(argv[2], NULL);
> @@ -677,15 +699,19 @@ static int do_bootefi(struct cmd_tbl *cmdtp, int flag, int argc,
>  		return do_efi_selftest();
>  #endif
>  
> -	return do_bootefi_image(argv[1]);
> +	return do_bootefi_image(argv[1], argc > 3 ? argv[3] : NULL);
>  }
>  
>  #ifdef CONFIG_SYS_LONGHELP
>  static char bootefi_help_text[] =
> -	"<image address> [fdt address]\n"
> +	"<image address> [fdt address [image size]]\n"
>  	"  - boot EFI payload stored at address <image address>.\n"
>  	"    If specified, the device tree located at <fdt address> gets\n"
>  	"    exposed as EFI configuration table.\n"
> +	"    The image size is required if this is not a preloaded image, but\n"
> +	"    it must be omitted if the image was preloaded.\n"
> +	"    The <fdt address> parameter accepts '-' to indicate FDT already\n"
> +	"    installed or pre-specified in fdt_addr or fdtcontroladdr.\n"
>  #ifdef CONFIG_CMD_BOOTEFI_HELLO
>  	"bootefi hello\n"
>  	"  - boot a sample Hello World application stored within U-Boot\n"
> @@ -707,7 +733,7 @@ static char bootefi_help_text[] =
>  #endif
>  
>  U_BOOT_CMD(
> -	bootefi, 3, 0, do_bootefi,
> +	bootefi, 4, 0, do_bootefi,
>  	"Boots an EFI payload from memory",
>  	bootefi_help_text
>  );
> -- 
> 2.33.0
>