Should I submit a new patch with the alignment set to 8 bytes? I would think a hard coded 8 bytes would not be the best solution, since not all architectures will need that much alignment. I suspect some would work with any alignment, and most 32-bit archs would be fine with 4-byte alignment.
Our released software is actually using a patch to align to 4096 bytes, but I knew that was unnecessarily large. I was not really sure what would be an appropriate value here, and took a guess at ARCH_DMA_MINALIGN when I cleaned it up for submitting upstream. Is there a better define to use?
I am also interested to know where the 8 byte alignment requirement is documented.
Reuben
-----Original Message----- From: Tom Rini trini@konsulko.com Sent: Tuesday, 25 August 2020 2:27 am To: Reuben Dowle reuben.dowle@4rf.com Cc: u-boot@lists.denx.de Subject: Re: [PATCH] Fix data abort caused by mis-aligning fit data in
On Fri, Jul 24, 2020 at 05:19:39AM +0000, Reuben Dowle wrote:
Attempting to place device tree immediately after an image in memory can lead to mis-aligned data accesses if that image size is not divisible by the alignment requirements of the architecture.
Data aborts caused by this were observed on a custom Marvel A388 based system, where the image was a uboot FIT file. The total size varies depending on the uboot device tree size, which does not always lead to
correct alignment.
Signed-off-by: Reuben Dowle reuben.dowle@4rf.com
common/spl/spl_fit.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/common/spl/spl_fit.c b/common/spl/spl_fit.c index 365104f..d221075 100644 --- a/common/spl/spl_fit.c +++ b/common/spl/spl_fit.c @@ -349,9 +349,9 @@ static int spl_fit_append_fdt(struct spl_image_info *spl_image,
/* * Use the address following the image as target address for the
* device tree.
* device tree. Ensure that address is appropriately aligned.
- image_info.load_addr = spl_image->load_addr + spl_image->size;
- image_info.load_addr = ALIGN(spl_image->load_addr + spl_image-
size, +ARCH_DMA_MINALIGN);
/* Figure out which device tree the board wants to use */ node = spl_fit_get_image_node(fit, images, FIT_FDT_PROP,
index++);
Sorry for the late reply here. While we do need to ensure that the device tree is aligned, the documented alignment requirement for all platforms is 8 byte, so we should document and use that here in case future platforms require a higher alignment. Thanks!
-- Tom