[PATCH] boot: image-fit: Add runtime flag to always relocate overlays

[Jamie Gibbons]

Some platforms 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);
 
 				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;
+			}
 		}
 
 		err = fdt_open_into(ov, ovcopy, ovcopylen);
diff --git a/include/image.h b/include/image.h
index 34efac6056d..9b174ea6233 100644
--- a/include/image.h
+++ b/include/image.h
@@ -707,12 +707,15 @@ int boot_get_setup_fit(struct bootm_headers *images, uint8_t arch,
  * @param arch		Expected architecture (IH_ARCH_...)
  * @param datap		Returns address of loaded image
  * @param lenp		Returns length of loaded image
+ * @param always_relocate_overlay	If true, always copy overlays to an 8-byte
+ *			aligned buffer before applying (prevents alignment errors)
  *
  * Return: node offset of base image, or -ve error code on error
  */
 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);
 
 /**
  * fit_image_load() - load an image from a FIT
-- 
2.43.0