Re: [PATCH v3 1/9] spl: Add generic spl_load function

Hello.

Thank you for your work, simplifying and generalizing code, and sorry that I hadn't seen this series before.

I'm new to U-Boot so I'm sorry if I waste your time with silly questions, but I can't seem to understand some details.

1- Does some info->read implementation ever want its buffer aligned to ARCH_DMA_MINALIGN ? I thought so, because of some code using aligned buffers, but I can't find it documented. Must be too obvious except for me ?

2- What constraints do we expect about the buffer returned by spl_get_load_buffer(0, size) ? From what I see it would seem to be often just CONFIG_SYS_TEXT_BASE ? Do we know CONFIG_SYS_TEXT_BASE is DMA aligned ? (I think it will be). Does it need to be in "the middle" of RAM, with room before it? grep -E 'CONFIG_SYS_TEXT_BASE=0(x0+)?\s*$' configs/* returns some 35 boards with CONFIG_SYS_TEXT_BASE=0 Can we assume we can write before the buffer and after buffer+size?

3- do all implementations of info->read expect the size to be in ARCH_DMA_ALIGN units, not a size in bytes when there's info->filename ?

spl_fat has filename, bl_len=1 but expects size in bytes, not in blocks of length ARCH_DMA_MINALIGN (which could be >1)

on the other hand (doesn't seem to be touched by this series yet?) spl_imx_romapi has no filename but expects size in bytes, not in bl_len=pagesize units ?

El Thu, May 05, 2022 at 04:16:47PM -0400, Sean Anderson deia:

diff --git a/common/spl/spl.c b/common/spl/spl.c index c9750ee163..f9a1cfc71e 100644 --- a/common/spl/spl.c +++ b/common/spl/spl.c @@ -399,6 +399,74 @@ 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;

does it work for spl_fat (and spl_imx_romapi if ever needed)? and should this or those be fixed ?

• 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__, bl_len,

•      bl_mask, bl_shift);
  

• buf -= overhead;

buf could be 0 ? If buf was aligned on entry can it be unaligned now, and does it need to be aligned ?

• size = (size + overhead + bl_mask) >> bl_shift;

ditto for spl_fat (and spl_imx_romapi) ?

• offset = offset >> bl_shift;
• debug("info->read(info, %lx, %lx, %p)\n", (ulong)offset, (ulong)size,

•      buf);
  

• ret = info->read(info, offset, size, buf);

This could read some bytes before the buf pointer that was given to us and beyond buf+size values received as arguments.

We were given bytes and read multiples of bl_len (or ARCH_DMA_MINALIGN) bytes, and then there's overhead.

Is this always ok ?

• 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);
  

maybe extra = max(info->bl_len, ARCH_DMA_MINALIGN) - 1; /* could be more precise, less wasteful */ buf = spl_get_load_buffer(extra , size + extra) ;

or maybe better

buf = spl_get_load_buffer(0, size + 2 * extra) + extra ;

or something, to prevent buf being 0 and make sure we have almost 1 buffer before and one buffer after the image size to cater for images unaligned in media ?

Also any consideration needed for the (DMA?) alignment of buf ?

• 	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);
  

This looks like maybe it could run into the same problem as spl_load_fit_image

http://patchwork.ozlabs.org/project/uboot/patch/20220609152414.1518919-1-jer...

Namely that the extra data in the media blocks before and after the image can get written outside [load_addr, load_addr+length) and give trouble (in the case Jerome Forissier found, writes to 0xff3b2XYZ were overwriting 0xff3b0XYZ on rk3399 because INTMEM1 was only a 8 KiB SRAM). That was solved by optionally reading into an aligned buffer and copying from there to load_addr without overflow (in chunks, but it could be at once if there's room).

But I'm no longer sure in which case I am, and when can we reach this. Non FIT image that is not inside a FIT image? I don't think current Rock Pi 4 would get here, but maybe loading from something else or in the future going to binman, or something ?

+}

__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 6134aba857..025fffb895 100644 --- a/include/spl.h +++ b/include/spl.h @@ -237,7 +237,7 @@ 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
  */

@@ -609,6 +609,34 @@ 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.
    

declare whether read must be able to read from unaligned buffers ?

• • @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.
    

The size in bytes. If 0 , then the size will be

• • @sectors: The offset from the start if @bootdev, in units of @info->bl_len.

if -> of maybe (nitpick) in units of @info->bl_len. -> in units of @info->bl_len bytes.

• •       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

Thanks for your patience, on top of for your code.