[PATCH] boot: image-fit: Add runtime flag to always relocate overlays
Marek Vasut
marek.vasut at mailbox.org
Fri Feb 6 20:06:38 CET 2026
On 2/6/26 4:14 PM, Jamie Gibbons wrote:
> Some platforms
All platforms, DTs and DTOs have to be 8 Byte aligned, always, period.
> require device tree overlays (DTOs) to be 8-byte aligned
> when applying them with libfdt. Previously, the code did not guarantee
> this alignment, which could result in alignment errors during overlay
> application.
> Introduce a new runtime parameter, always_relocate_overlay, to
> boot_get_fdt_fit(). When set, overlays are always copied to an 8-byte
> aligned buffer before being passed to fdt_open_into().
> This resolves issues with FDT overlay application on platforms that
> require strict alignment.
>
> Fixes: 8fbcc0e0e839 ("boot: Assure FDT is always at 8-byte aligned address")
>
> Signed-off-by: Jamie Gibbons <jamie.gibbons at microchip.com>
> ---
> boot/image-fdt.c | 2 +-
> boot/image-fit.c | 23 +++++++++++++++++------
> include/image.h | 5 ++++-
> 3 files changed, 22 insertions(+), 8 deletions(-)
>
> diff --git a/boot/image-fdt.c b/boot/image-fdt.c
> index a3a4fb8b558..33fd4248acd 100644
> --- a/boot/image-fdt.c
> +++ b/boot/image-fdt.c
> @@ -431,7 +431,7 @@ static int select_fdt(struct bootm_headers *images, const char *select, u8 arch,
> fdt_noffset = boot_get_fdt_fit(images, fdt_addr,
> &fit_uname_fdt,
> &fit_uname_config,
> - arch, &load, &len);
> + arch, &load, &len, true);
This flag is always true, do we actually need it ?
> if (fdt_noffset < 0)
> return -ENOENT;
> diff --git a/boot/image-fit.c b/boot/image-fit.c
> index d2b0a7daccc..a3fa2a01463 100644
> --- a/boot/image-fit.c
> +++ b/boot/image-fit.c
> @@ -2370,7 +2370,8 @@ int boot_get_setup_fit(struct bootm_headers *images, uint8_t arch,
> #ifndef USE_HOSTCC
> int boot_get_fdt_fit(struct bootm_headers *images, ulong addr,
> const char **fit_unamep, const char **fit_uname_configp,
> - int arch, ulong *datap, ulong *lenp)
> + int arch, ulong *datap, ulong *lenp,
> + bool always_relocate_overlay)
> {
> int fdt_noffset, cfg_noffset, count;
> const void *fit;
> @@ -2492,11 +2493,21 @@ int boot_get_fdt_fit(struct bootm_headers *images, ulong addr,
> ov = map_sysmem(ovload, ovlen);
>
> ovcopylen = ALIGN(fdt_totalsize(ov), SZ_4K);
> - ovcopy = malloc(ovcopylen);
> - if (!ovcopy) {
> - printf("failed to duplicate DTO before application\n");
> - fdt_noffset = -ENOMEM;
> - goto out;
> + if (always_relocate_overlay) {
> + ovcopy = aligned_alloc(8, ovcopylen);
> + if (!ovcopy) {
> + printf("failed to allocate aligned DTO buffer\n");
> + fdt_noffset = -ENOMEM;
> + goto out;
> + }
> + memcpy(ovcopy, ov, ovlen);
> + } else {
> + ovcopy = malloc(ovcopylen);
> + if (!ovcopy) {
> + printf("failed to duplicate DTO before application\n");
> + fdt_noffset = -ENOMEM;
> + goto out;
> + }
Looking at this, if the problem is $ov aligned to 4 Bytes, then $base a
bit below could also be aligned to 4 Bytes if there are two or more DTs
in the fitImage without external data. Can you please try the attached
patch and see if that still works ?
diff --git a/boot/image-fit.c b/boot/image-fit.c
index 3ed69b5f7bc..845e769a7e3 100644
--- a/boot/image-fit.c
+++ b/boot/image-fit.c
@@ -2368,6 +2368,48 @@ int boot_get_setup_fit(struct bootm_headers
*images, uint8_t arch,
}
#ifndef USE_HOSTCC
+#ifdef CONFIG_OF_LIBFDT_OVERLAY
+static int boot_get_fdt_fit_into_buffer(ulong loadaddr, ulong loadlen,
void **fdtdstbuf)
+{
+ void *fdtsrcbuf, *map;
+ ulong fdtdstlen;
+ int err;
+
+ map = map_sysmem(loadaddr, loadlen);
+
+ /* Set up source buffer, make sure DT in the buffer is 8-Bytes aligned */
+ if (!IS_ALIGNED((uintptr_t)map, 8)) {
+ fdtsrcbuf = aligned_alloc(8, loadlen);
+ if (!fdtsrcbuf)
+ return -ENOMEM;
+ memcpy(fdtsrcbuf, map, loadlen);
+ } else {
+ fdtsrcbuf = map;
+ }
+
+ /* Set up destination buffer, make sure DT in the buffer is 8-Bytes
aligned */
+ fdtdstlen = ALIGN(fdt_totalsize(fdtsrcbuf), SZ_4K);
+ fdtdstbuf = aligned_alloc(8, fdtdstlen);
+ if (!fdtdstbuf) {
+ printf("failed to duplicate DTO before application\n");
+ if (!IS_ALIGNED((uintptr_t)map, 8))
+ free(fdtsrcbuf);
+ return -ENOMEM;
+ }
+
+ err = fdt_open_into(fdtsrcbuf, *fdtdstbuf, fdtdstlen);
+ if (!IS_ALIGNED((uintptr_t)map, 8))
+ free(fdtsrcbuf);
+ if (err < 0) {
+ printf("failed on fdt_open_into for DTO: %s\n",
+ fdt_strerror(err));
+ return err;
+ }
+
+ return 0;
+};
+#endif
+
int boot_get_fdt_fit(struct bootm_headers *images, ulong addr,
const char **fit_unamep, const char **fit_uname_configp,
int arch, ulong *datap, ulong *lenp)
@@ -2380,7 +2422,7 @@ int boot_get_fdt_fit(struct bootm_headers *images,
ulong addr,
char *next_config = NULL;
ulong load, len;
#ifdef CONFIG_OF_LIBFDT_OVERLAY
- ulong ovload, ovlen, ovcopylen;
+ ulong ovload, ovlen;
const char *uconfig;
const char *uname;
/*
@@ -2391,7 +2433,7 @@ int boot_get_fdt_fit(struct bootm_headers *images,
ulong addr,
* Instead, let's be lazy and use void *.
*/
char *of_flat_tree;
- void *base, *ov, *ovcopy = NULL;
+ void *base, *ovcopy = NULL;
int i, err, noffset, ov_noffset;
#endif
@@ -2489,17 +2531,7 @@ int boot_get_fdt_fit(struct bootm_headers
*images, ulong addr,
}
debug("%s loaded at 0x%08lx len=0x%08lx\n",
uname, ovload, ovlen);
- ov = map_sysmem(ovload, ovlen);
-
- ovcopylen = ALIGN(fdt_totalsize(ov), SZ_4K);
- ovcopy = malloc(ovcopylen);
- if (!ovcopy) {
- printf("failed to duplicate DTO before application\n");
- fdt_noffset = -ENOMEM;
- goto out;
- }
-
- err = fdt_open_into(ov, ovcopy, ovcopylen);
+ err = boot_get_fdt_fit_into_buffer(ovload, ovlen, &ovcopy);
if (err < 0) {
printf("failed on fdt_open_into for DTO: %s\n",
fdt_strerror(err));
@@ -2507,8 +2539,7 @@ int boot_get_fdt_fit(struct bootm_headers *images,
ulong addr,
goto out;
}
- base = map_sysmem(load, len + ovlen);
- err = fdt_open_into(base, base, len + ovlen);
+ err = boot_get_fdt_fit_into_buffer(load, len + ovlen, &base);
if (err < 0) {
printf("failed on fdt_open_into: %s\n",
fdt_strerror(err));
--
2.51.0
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