[PATCH v2] Fix data abort caused by mis-aligning FIT data

[PATCH v2] Fix data abort caused by mis-aligning FIT data

[Reuben Dowle]

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.

The minimum alignment specified for ARM [1] and ARM64 [2] linux booting has been
used

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/arm/booting.rst#n126
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/arm64/booting.rst#n45

Signed-off-by: Reuben Dowle <reuben.dowle@4rf.com>
---
 common/spl/spl_fit.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/common/spl/spl_fit.c b/common/spl/spl_fit.c
index 365104f..a8bfd38 100644
--- a/common/spl/spl_fit.c
+++ b/common/spl/spl_fit.c
@@ -349,9 +349,12 @@ 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. Load address is aligned to 8 bytes to match the required
+	 * alignment specified for linux arm [1] and arm 64 [2] booting
+	 * [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/arm/booting.rst#n126
+	 * [2]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/arm64/booting.rst#n45
 	 */
-	image_info.load_addr = spl_image->load_addr + spl_image->size;
+	image_info.load_addr = ALIGN(spl_image->load_addr + spl_image->size, 8);
 
 	/* Figure out which device tree the board wants to use */
 	node = spl_fit_get_image_node(fit, images, FIT_FDT_PROP, index++);
-- 
2.7.4

[PATCH v2] Fix data abort caused by mis-aligning FIT data

[Tom Rini]

On Tue, Sep 01, 2020 at 09:32:01PM +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.
> 
> The minimum alignment specified for ARM [1] and ARM64 [2] linux booting has been
> used
> 
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/arm/booting.rst#n126
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/arm64/booting.rst#n45
> 
> Signed-off-by: Reuben Dowle <reuben.dowle@4rf.com>

Applied to u-boot/master, thanks!

-- 
Tom
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