[PATCH v4 04/10] of: reserved_mem: split alloc_reserved_mem_array() from fdt_scan_reserved_mem_late()

[Wandun Chen <chenwandun1@gmail.com>]

From: Wandun Chen <chenwandun@lixiang.com>

Prepare for storing /memreserve/ entries in the reserved_mem array.
alloc_reserved_mem_array was skipped if the device tree lacks a
/reserved-memory node, pointer 'reserved_mem' continues to reference
the reserved_mem_array which lives in __initdata, storing
/memreserve/ entries into reserved_mem_array would result in metadata
loss, and an out-of-bounds memory access will occur if the device
tree contains more than MAX_RESERVED_REGIONS /memreserve/ entries.

So split alloc_reserved_mem_array() from fdt_scan_reserved_mem_late(),
and call alloc_reserved_mem_array() whether or not there is a
/reserved-memory node.

No functional change.
The actual /memreserve/ population is added in a follow-up patch.

Signed-off-by: Wandun Chen <chenwandun@lixiang.com>
---
 drivers/of/fdt.c             |  7 +++++--
 drivers/of/of_private.h      |  1 +
 drivers/of/of_reserved_mem.c | 11 ++---------
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 26f66046cc32..b97775f6c9d4 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1282,8 +1282,11 @@ void __init unflatten_device_tree(void)
 {
 	void *fdt = initial_boot_params;
 
-	/* Save the statically-placed regions in the reserved_mem array */
-	fdt_scan_reserved_mem_late();
+	/* Attempt dynamic allocation of a new reserved_mem array */
+	if (!alloc_reserved_mem_array()) {
+		/* Save the statically-placed regions in the reserved_mem array */
+		fdt_scan_reserved_mem_late();
+	}
 
 	/* Populate an empty root node when bootloader doesn't provide one */
 	if (!fdt) {
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 0ae16da066e2..81c8ec9378b9 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -187,6 +187,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
 
 int fdt_scan_reserved_mem(void);
 void __init fdt_scan_reserved_mem_late(void);
+int __init alloc_reserved_mem_array(void);
 
 bool of_fdt_device_is_available(const void *blob, unsigned long node);
 
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index e1bd35115cc1..f6c02b37deb7 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -69,13 +69,13 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
  * the initial static array is copied over to this new array and
  * the new array is used from this point on.
  */
-static int __init alloc_reserved_mem_array(void)
+int __init alloc_reserved_mem_array(void)
 {
 	struct reserved_mem *new_array;
 	size_t alloc_size, copy_size, memset_size;
 	int ret;
 
-	if (!total_reserved_mem_cnt)
+	if (!initial_boot_params || !total_reserved_mem_cnt)
 		return -ENODEV;
 
 	alloc_size = array_size(total_reserved_mem_cnt, sizeof(*new_array));
@@ -266,17 +266,10 @@ void __init fdt_scan_reserved_mem_late(void)
 	phys_addr_t base, size;
 	int node, child;
 
-	if (!fdt)
-		return;
-
 	node = fdt_path_offset(fdt, "/reserved-memory");
 	if (node < 0)
 		return;
 
-	/* Attempt dynamic allocation of a new reserved_mem array */
-	if (alloc_reserved_mem_array())
-		return;
-
 	if (__reserved_mem_check_root(node))
 		return;
 
-- 
2.43.0