From c4aadcb58906f4a4c0bd120dbadb65df1f84b94c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@baylibre.com>
Date: Mon, 21 Oct 2024 09:23:56 +0200
Subject: [PATCH] Restore phandle references from __local_fixups__ node
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The __local_fixups__ node contains information about phandles. Parse it
to improve the result when decompiling a device tree blob.

Note that this is essential to do before the __local_fixups__ node is
removed in generate_local_fixups_tree() because otherwise the
information contained in that node is lost.

Fixes: 915daadbb62d ("Start with empty __local_fixups__ and __fixups__ nodes")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 dtc.c        |  2 ++
 dtc.h        |  2 ++
 livetree.c   | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 treesource.c | 33 ++++++++++++++++++++++++++++++
 4 files changed, 94 insertions(+)

diff --git a/dtc.c b/dtc.c
index 63a6c85..9f90b37 100644
--- a/dtc.c
+++ b/dtc.c
@@ -343,6 +343,8 @@ int main(int argc, char *argv[])
 	if (generate_symbols)
 		generate_label_tree(dti, "__symbols__", true);
 
+	local_fixup_phandles(dti, "__local_fixups__");
+
 	if (generate_fixups) {
 		generate_fixups_tree(dti, "__fixups__");
 		generate_local_fixups_tree(dti, "__local_fixups__");
diff --git a/dtc.h b/dtc.h
index f97f3c2..d07a583 100644
--- a/dtc.h
+++ b/dtc.h
@@ -343,6 +343,7 @@ void generate_labels_from_tree(struct dt_info *dti, const char *name);
 void generate_label_tree(struct dt_info *dti, const char *name, bool allocph);
 void generate_fixups_tree(struct dt_info *dti, const char *name);
 void generate_local_fixups_tree(struct dt_info *dti, const char *name);
+void local_fixup_phandles(struct dt_info *dti, const char *name);
 
 /* Checks */
 
@@ -358,6 +359,7 @@ struct dt_info *dt_from_blob(const char *fname);
 
 /* Tree source */
 
+void add_phandle_marker(struct dt_info *dti, struct property *prop, unsigned int offset);
 void dt_to_source(FILE *f, struct dt_info *dti);
 struct dt_info *dt_from_source(const char *f);
 
diff --git a/livetree.c b/livetree.c
index cc54f97..10b767d 100644
--- a/livetree.c
+++ b/livetree.c
@@ -1103,3 +1103,60 @@ void generate_local_fixups_tree(struct dt_info *dti, const char *name)
 					    build_and_name_child_node(dti->dt, name),
 					    dti->dt);
 }
+
+static void local_fixup_phandles_node(struct dt_info *dti, struct node *lf, struct node *n)
+{
+	struct property *lfp;
+	struct node *lfsubnode;
+
+	for_each_property(lf, lfp) {
+		struct property *p = get_property(n, lfp->name);
+		fdt32_t *offsets = (fdt32_t *)lfp->val.val;
+		size_t i;
+
+		if (!p) {
+			if (quiet < 1)
+				fprintf(stderr, "Warning: Property %s in %s referenced in __local_fixups__ missing\n",
+					lfp->name, n->fullpath);
+			continue;
+		}
+
+		/*
+		 * Each property in the __local_fixups__ tree is a concatenation
+		 * of offsets, so it must be a multiple of sizeof(fdt32_t).
+		 */
+		if (lfp->val.len % sizeof(fdt32_t)) {
+			if (quiet < 1)
+				fprintf(stderr, "Warning: property %s in /__local_fixups__%s malformed\n",
+					lfp->name, n->fullpath);
+			continue;
+		}
+
+		for (i = 0; i < lfp->val.len / sizeof(fdt32_t); i++)
+			add_phandle_marker(dti, p, dtb_ld32(offsets + i));
+	}
+
+	for_each_child(lf, lfsubnode) {
+		struct node *subnode = get_subnode(n, lfsubnode->name);
+
+		if (!subnode) {
+			if (quiet < 1)
+				fprintf(stderr, "Warning: node %s/%s referenced in __local_fixups__ missing\n",
+					lfsubnode->name, n->fullpath);
+			continue;
+		}
+
+		local_fixup_phandles_node(dti, lfsubnode, subnode);
+	}
+}
+
+void local_fixup_phandles(struct dt_info *dti, const char *name)
+{
+	struct node *an;
+
+	an = get_subnode(dti->dt, name);
+	if (!an)
+		return;
+
+	local_fixup_phandles_node(dti, an, dti->dt);
+}
diff --git a/treesource.c b/treesource.c
index 5764959..5b8d7a6 100644
--- a/treesource.c
+++ b/treesource.c
@@ -183,6 +183,39 @@ static void add_string_markers(struct property *prop, unsigned int offset, int l
 		mi = add_marker(mi, TYPE_STRING, offset + l, NULL);
 }
 
+void add_phandle_marker(struct dt_info *dti, struct property *prop, unsigned int offset)
+{
+	cell_t phandle;
+	struct node *refn;
+	char *ref;
+
+	if (prop->val.len < offset + 4) {
+		if (quiet < 1)
+			fprintf(stderr,
+				"Warning: property %s too short to contain a phandle at offset %u\n",
+				prop->name, offset);
+
+	}
+
+	phandle = dtb_ld32(prop->val.val + offset);
+	refn = get_node_by_phandle(dti->dt, phandle);
+
+	if (!refn) {
+		if (quiet < 1)
+			fprintf(stderr,
+				"Warning: node referenced by phandle 0x%x in property %s not found\n",
+				phandle, prop->name);
+		return;
+	}
+
+	if (refn->labels)
+		ref = refn->labels->label;
+	else
+		ref = refn->fullpath;
+
+	add_marker(&prop->val.markers, REF_PHANDLE, offset, ref);
+}
+
 static enum markertype guess_value_type(struct property *prop, unsigned int offset, int len)
 {
 	const char *p = prop->val.val + offset;