[PATCH v2 1/6] efi_loader: add RAM disk device path

[Heinrich Schuchardt]

On 14.07.23 07:44, Masahisa Kojima wrote:
> This is a preparation to add the EFI_RAM_DISK_PROTOCOL.
> This commit adds the RAM disk device path structure
> and text conversion to Device Path to Text Protocol.
>
> Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
> ---
> No update since v1
>
>   include/efi_api.h                        | 19 +++++++++++++++++++
>   lib/efi_loader/efi_device_path_to_text.c | 14 ++++++++++++++
>   2 files changed, 33 insertions(+)
>
> diff --git a/include/efi_api.h b/include/efi_api.h
> index 55a4c989fc..4ee4a1b5e9 100644
> --- a/include/efi_api.h
> +++ b/include/efi_api.h
> @@ -682,6 +682,7 @@ struct efi_device_path_uri {
>   #  define DEVICE_PATH_SUB_TYPE_CDROM_PATH	0x02
>   #  define DEVICE_PATH_SUB_TYPE_VENDOR_PATH	0x03
>   #  define DEVICE_PATH_SUB_TYPE_FILE_PATH	0x04
> +#  define DEVICE_PATH_SUB_TYPE_RAM_DISK_PATH	0x09
>
>   struct efi_device_path_hard_drive_path {
>   	struct efi_device_path dp;
> @@ -705,6 +706,24 @@ struct efi_device_path_file_path {
>   	u16 str[];
>   } __packed;
>
> +/* This GUID defines a RAM Disk supporting a raw disk format in volatile memory */
> +#define EFI_VIRTUAL_DISK_GUID \
> +	EFI_GUID(0x77ab535a, 0x45fc, 0x624b, \
> +	0x55, 0x60, 0xf7, 0xb2, 0x81, 0xd1, 0xf9, 0x6e)
> +
> +/* This GUID defines a RAM Disk supporting an ISO image in volatile memory */
> +#define EFI_VIRTUAL_CD_GUID \
> +	EFI_GUID(0x3d5abd30, 0x4175, 0x87ce, \
> +		 0x6d, 0x64, 0xd2, 0xad, 0xe5, 0x23, 0xc4, 0xbb)
> +
> +struct efi_device_path_ram_disk_path {
> +	struct efi_device_path dp;
> +	u64 starting_address;
> +	u64 ending_address;
> +	efi_guid_t disk_type_guid;
> +	u16 disk_instance;
> +} __packed;
> +
>   #define EFI_BLOCK_IO_PROTOCOL_GUID \
>   	EFI_GUID(0x964e5b21, 0x6459, 0x11d2, \
>   		 0x8e, 0x39, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b)
> diff --git a/lib/efi_loader/efi_device_path_to_text.c b/lib/efi_loader/efi_device_path_to_text.c
> index 8c76d8be60..4395e79f33 100644
> --- a/lib/efi_loader/efi_device_path_to_text.c
> +++ b/lib/efi_loader/efi_device_path_to_text.c
> @@ -324,6 +324,20 @@ static char *dp_media(char *s, struct efi_device_path *dp)
>   		free(buffer);
>   		break;
>   	}
> +	case DEVICE_PATH_SUB_TYPE_RAM_DISK_PATH: {
> +		struct efi_device_path_ram_disk_path *rddp =
> +			(struct efi_device_path_ram_disk_path *)dp;
> +		u64 start;
> +		u64 end;
> +
> +		/* Copy from packed structure to aligned memory */
> +		memcpy(&start, &rddp->starting_address, sizeof(start));
> +		memcpy(&end, &rddp->ending_address, sizeof(end));
> +
> +		s += sprintf(s, "RamDisk(0x%llx,%llx,%pUl,0x%x)", start, end,
> +			     &rddp->disk_type_guid, rddp->disk_instance);

If there is no alignment guarantee for starting_address, then the same
is true for disk_instance which may spread over two u64 blocks.

In case of DEVICE_PATH_SUB_TYPE_MEMORY we don't use memcpy() to align u64.

I don't think we call device_path_to_text before allow_unaligned().

There is a family of functions like get_unaligned_le64() if we should
ever need to a align a value. Or we could copy the whole device path node.

Best regards

Heinrich

> +		break;
> +	}
>   	default:
>   		s = dp_unknown(s, dp);
>   		break;