From 24888292cddb474a52f945d6ed263f44ec1222b6 Mon Sep 17 00:00:00 2001
From: Kyle Evans <kevans@FreeBSD.org>
Date: Sun, 31 Dec 2017 05:22:26 +0000
Subject: [PATCH] stand/fdt: Make fdt_overlay_apply signature-compatible with
 libfdt

libfdt will assume a writable fdt overlay blob has been passed in, so make
ours compatible to allow easier review when we try to drop libfdt into
place. overlay from the calling context is writable, making it safe to
simply rip out everything related to copying the overlay blob in
fdt_overlay_apply.

I note here that we still have problems: fdt_overlay_apply, both our version
and libfdt's, may fail and have already clobbered the base fdt to some
extent. Future work will make sure we don't apply a potentially bogus fdt,
instead discarding the base fdt if we had an error.

Reviewed by:	gonzo
Differential Revision:	https://reviews.freebsd.org/D13695
---
 stand/fdt/fdt_loader_cmd.c |  3 ++-
 stand/fdt/fdt_overlay.c    | 34 ++++++++--------------------------
 stand/fdt/fdt_overlay.h    |  2 +-
 3 files changed, 11 insertions(+), 28 deletions(-)

diff --git a/stand/fdt/fdt_loader_cmd.c b/stand/fdt/fdt_loader_cmd.c
index f5b7d5b6d198..849e42a3ed56 100644
--- a/stand/fdt/fdt_loader_cmd.c
+++ b/stand/fdt/fdt_loader_cmd.c
@@ -386,7 +386,8 @@ fdt_apply_overlays()
 	for (fp = file_findfile(NULL, "dtbo"); fp != NULL; fp = fp->f_next) {
 		printf("applying DTB overlay '%s'\n", fp->f_name);
 		COPYOUT(fp->f_addr, overlay, fp->f_size);
-		fdt_overlay_apply(new_fdtp, overlay, fp->f_size);
+		/* Both overlay and new_fdtp may be modified in place */
+		fdt_overlay_apply(new_fdtp, overlay);
 	}
 
 	free(fdtp);
diff --git a/stand/fdt/fdt_overlay.c b/stand/fdt/fdt_overlay.c
index e49c5d586e29..9763f2310a6a 100644
--- a/stand/fdt/fdt_overlay.c
+++ b/stand/fdt/fdt_overlay.c
@@ -409,41 +409,23 @@ fdt_overlay_apply_fragments(void *main_fdtp, void *overlay_fdtp)
 }
 
 int
-fdt_overlay_apply(void *main_fdtp, void *overlay_fdtp, size_t overlay_length)
+fdt_overlay_apply(void *main_fdtp, void *overlay_fdtp)
 {
-	void *overlay_copy;
-	int rv;
 
-	rv = 0;
-
-	/* We modify overlay in-place, so we need writable copy */
-	overlay_copy = malloc(overlay_length);
-	if (overlay_copy == NULL) {
-		printf("failed to allocate memory for overlay copy\n");
+	if (fdt_overlay_do_fixups(main_fdtp, overlay_fdtp) < 0) {
+		printf("failed to perform fixups in overlay\n");
 		return (-1);
 	}
 
-	memcpy(overlay_copy, overlay_fdtp, overlay_length);
-
-	if (fdt_overlay_do_fixups(main_fdtp, overlay_copy) < 0) {
-		printf("failed to perform fixups in overlay\n");
-		rv = -1;
-		goto out;
-	}
-
-	if (fdt_overlay_do_local_fixups(main_fdtp, overlay_copy) < 0) {
+	if (fdt_overlay_do_local_fixups(main_fdtp, overlay_fdtp) < 0) {
 		printf("failed to perform local fixups in overlay\n");
-		rv = -1;
-		goto out;
+		return (-1);
 	}
 
-	if (fdt_overlay_apply_fragments(main_fdtp, overlay_copy) < 0) {
+	if (fdt_overlay_apply_fragments(main_fdtp, overlay_fdtp) < 0) {
 		printf("failed to apply fragments\n");
-		rv = -1;
+		return (-1);
 	}
 
-out:
-	free(overlay_copy);
-
-	return (rv);
+	return (0);
 }
diff --git a/stand/fdt/fdt_overlay.h b/stand/fdt/fdt_overlay.h
index 0f9134384d3c..4b9933e97150 100644
--- a/stand/fdt/fdt_overlay.h
+++ b/stand/fdt/fdt_overlay.h
@@ -29,6 +29,6 @@
 #ifndef FDT_OVERLAY_H
 #define FDT_OVERLAY_H
 
-int fdt_overlay_apply(void *main_fdtp, void *overlay_fdtp, size_t overlay_length);
+int fdt_overlay_apply(void *main_fdtp, void *overlay_fdtp);
 
 #endif /* FDT_OVERLAY_H */