[RFC PATCH 1/7] spl: Add generic spl_load function

[Stefan Roese]

On 4/1/22 21:03, Sean Anderson wrote:
> Implementers of SPL_LOAD_IMAGE_METHOD have to correctly determine what
> type of image is being loaded and then call the appropriate image load
> function correctly. This is tricky, because some image load functions
> expect the whole image to already be loaded (CONFIG_SPL_LOAD_FIT_FULL),
> some will load the image automatically using spl_load_info.read()
> (CONFIG_SPL_LOAD_FIT/CONFIG_SPL_LOAD_IMX_CONTAINER), and some just parse
> the header and expect the caller to do the actual loading afterwards
> (legacy/raw images). Load methods often only support a subset of the
> above methods, meaning that not all image types can be used with all
> load methods. Further, the code to invoke these functions is
> duplicated between different load functions.
> 
> To address this problem, this commit introduces a "spl_load" function.
> It aims to handle image detection and correct invocation of each of the
> parse/load functions. spl_simple_read is a wrapper around
> spl_load_info.read with get_aligned_image* functions inlined for size
> purposes. Additionally, we assume that bl_len is a power of 2 so we can
> do bitshifts instead of divisions (which is smaller and faster).
> 
> Signed-off-by: Sean Anderson <sean.anderson at seco.com>
> ---
> 
>   common/spl/spl.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
>   include/spl.h    | 30 +++++++++++++++++++++++-
>   2 files changed, 90 insertions(+), 1 deletion(-)
> 
> diff --git a/common/spl/spl.c b/common/spl/spl.c
> index b452d4feeb..f26df7ac3f 100644
> --- a/common/spl/spl.c
> +++ b/common/spl/spl.c
> @@ -398,6 +398,67 @@ int spl_parse_image_header(struct spl_image_info *spl_image,
>   	return 0;
>   }
>   
> +static int spl_simple_read(struct spl_load_info *info, void *buf, size_t size,
> +			   size_t offset)
> +{
> +	int ret;
> +	size_t bl_len = info->filename ? ARCH_DMA_MINALIGN : bl_len;
> +	size_t bl_mask = bl_len - 1;
> +	size_t bl_shift = ffs(bl_mask);
> +	size_t overhead = offset & bl_mask;
> +

Nitpicking comment:

It's preferred in general to use the reverse XMAS tree ordering of the
declared variables. So I would expect at least to have "int ret" as
last statement above. If you address this, then please in the complete
series.

Reviewed-by: Stefan Roese <sr at denx.de>

Thanks,
Stefan

> +	buf -= overhead;
> +	size = (size + overhead + bl_mask) >> bl_shift;
> +	offset = offset >> bl_shift;
> +
> +	ret = info->read(info, offset, size, buf);
> +	return ret == size ? 0 : -EIO;
> +}
> +
> +int spl_load(struct spl_image_info *spl_image,
> +	     const struct spl_boot_device *bootdev, struct spl_load_info *info,
> +	     struct image_header *header, size_t size, size_t sector)
> +{
> +	int ret;
> +	size_t offset = sector * info->bl_len;
> +
> +	if (image_get_magic(header) == FDT_MAGIC) {
> +		if (IS_ENABLED(CONFIG_SPL_LOAD_FIT_FULL)) {
> +			void *buf;
> +
> +			/*
> +			 * In order to support verifying images in the FIT, we
> +			 * need to load the whole FIT into memory. Try and
> +			 * guess how much we need to load by using the total
> +			 * size. This will fail for FITs with external data,
> +			 * but there's not much we can do about that.
> +			 */
> +			if (!size)
> +				size = roundup(fdt_totalsize(header), 4);
> +			buf = spl_get_load_buffer(0, size);
> +			ret = spl_simple_read(info, buf, size, offset);
> +			if (ret)
> +				return ret;
> +
> +			return spl_parse_image_header(spl_image, bootdev, buf);
> +		}
> +
> +		if (IS_ENABLED(CONFIG_SPL_LOAD_FIT))
> +			return spl_load_simple_fit(spl_image, info, sector,
> +						   header);
> +	}
> +
> +	if (IS_ENABLED(CONFIG_SPL_LOAD_IMX_CONTAINER))
> +		return spl_load_imx_container(spl_image, info, sector);
> +
> +	ret = spl_parse_image_header(spl_image, bootdev, header);
> +	if (ret)
> +		return ret;
> +
> +	return spl_simple_read(info, (void *)spl_image->load_addr,
> +			       spl_image->size, offset + spl_image->offset);
> +}
> +
>   __weak void __noreturn jump_to_image_no_args(struct spl_image_info *spl_image)
>   {
>   	typedef void __noreturn (*image_entry_noargs_t)(void);
> diff --git a/include/spl.h b/include/spl.h
> index 8ceb3c0f09..6606f4e5f6 100644
> --- a/include/spl.h
> +++ b/include/spl.h
> @@ -236,7 +236,7 @@ struct spl_image_info {
>    *
>    * @dev: Pointer to the device, e.g. struct mmc *
>    * @priv: Private data for the device
> - * @bl_len: Block length for reading in bytes
> + * @bl_len: Block length for reading in bytes; must be a power of 2
>    * @filename: Name of the fit image file.
>    * @read: Function to call to read from the device
>    */
> @@ -608,6 +608,34 @@ int spl_load_image_ext_os(struct spl_image_info *spl_image,
>   			  struct spl_boot_device *bootdev,
>   			  struct blk_desc *block_dev, int partition);
>   
> +/**
> + * spl_load() - Parse a header and load the image
> + * @spl_image: Image data which will be filled in by this function
> + * @bootdev: The device to load from
> + * @info: Describes how to load additional information from @bootdev. At the
> + *        minimum, read() and bl_len must be populated.
> + * @header: The image header. This should already have been loaded. It may be
> + *          clobbered by the load process (if e.g. the load address overlaps).
> + * @size: The size of the image, if it is known in advance. Some boot devices
> + *        (such as filesystems) know how big an image is before parsing the
> + *        header. If this information is unknown, then the size will be
> + *        determined from the header.
> + * @sectors: The offset from the start if @bootdev, in units of @info->bl_len.
> + *           This should have the offset @header was loaded from. It will be
> + *           added to any offsets passed to @info->read().
> + *
> + * This function determines the image type (FIT, legacy, i.MX, raw, etc), calls
> + * the appropriate parsing function, determines the load address, and the loads
> + * the image from storage. It is designed to replace ad-hoc image loading which
> + * may not support all image types (especially when config options are
> + * involved).
> + *
> + * Return: 0 on success, or a negative error on failure
> + */
> +int spl_load(struct spl_image_info *spl_image,
> +	     const struct spl_boot_device *bootdev, struct spl_load_info *info,
> +	     struct image_header *header, size_t size, size_t sector);
> +
>   /**
>    * spl_early_init() - Set up device tree and driver model in SPL if enabled
>    *

Viele Grüße,
Stefan Roese

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