[PATCH v4 1/9] spl: Add generic spl_load function

[Heinrich Schuchardt]

On 7/24/23 19:12, 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>
> Reviewed-by: Stefan Roese <sr at denx.de>
> ---
>
> Changes in v4:
> - Fix format specifiers in debug prints
> - Reword/fix some of the doc comments for spl_load
>
> Changes in v3:
> - Fix using ffs instead of fls
> - Fix using not initializing bl_len when info->filename was NULL
>
> Changes in v2:
> - Use reverse-xmas-tree style for locals in spl_simple_read. This is not
>    complete, since overhead depends on bl_mask.
>
>   common/spl/spl.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++
>   include/spl.h    | 29 ++++++++++++++++++++-
>   2 files changed, 96 insertions(+), 1 deletion(-)
>
> diff --git a/common/spl/spl.c b/common/spl/spl.c
> index f09bb977814..3ef064009e8 100644
> --- a/common/spl/spl.c
> +++ b/common/spl/spl.c
> @@ -450,6 +450,74 @@ 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)
> +{
> +	size_t bl_len = info->filename ? ARCH_DMA_MINALIGN : info->bl_len;
> +	size_t bl_mask = bl_len - 1;
> +	size_t overhead = offset & bl_mask;
> +	size_t bl_shift = fls(bl_mask);
> +	int ret;
> +
> +	debug("%s: buf=%p size=%lx offset=%lx\n", __func__, buf, (long)size,
> +	      (long)offset);
> +	debug("%s: bl_len=%lx bl_mask=%lx bl_shift=%lx\n", __func__, (long)bl_len,
> +	      (long)bl_mask, (long)bl_shift);
> +
> +	buf -= overhead;
> +	size = (size + overhead + bl_mask) >> bl_shift;
> +	offset = offset >> bl_shift;
> +
> +	debug("info->read(info, %lx, %lx, %p)\n", (ulong)offset, (ulong)size,
> +	      buf);
> +	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 legacy_img_hdr *header, size_t size, size_t sector)

Hello Sean,

carving out common functionality is really a good path forward.

This function spl_load() receives a pointer to a read function in
info->read() and additionally the file header.

Why can't we move the reading of the header to spl_load() too?

Best regards

Heinrich

> +{
> +	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 92bcaa90a4a..06b34e70a44 100644
> --- a/include/spl.h
> +++ b/include/spl.h
> @@ -268,7 +268,7 @@ 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
>    */
> @@ -677,6 +677,33 @@ int spl_blk_load_image(struct spl_image_info *spl_image,
>   		       struct spl_boot_device *bootdev,
>   		       enum uclass_id uclass_id, int devnum, int partnum);
>
> +/**
> + * 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, in bytes, if it is known in advance. Some boot
> + *        devices (such as filesystems) know how big an image is before parsing
> + *        the header. If 0, then the size will be determined from the header.
> + * @sectors: The offset from the start of @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 legacy_img_hdr *header, size_t size, size_t sector);
> +
>   /**
>    * spl_early_init() - Set up device tree and driver model in SPL if enabled
>    *