Commit 463942de authored by Yuntao Wang's avatar Yuntao Wang Committed by Rob Herring (Arm)
Browse files

of/fdt: Fix the len check in early_init_dt_check_for_usable_mem_range() 



The len value is in bytes, while `dt_root_addr_cells + dt_root_size_cells`
is in cells (4 bytes per cell). Modulo calculation between them is
incorrect, the units must be converted first.

Use helper functions to simplify the code and fix this issue.

Fixes: fb319e77 ("of: fdt: Add memory for devices by DT property "linux,usable-memory-range"")
Fixes: 2af2b50a ("of: fdt: Add generic support for handling usable memory range property")
Fixes: 8f579b1c ("arm64: limit memory regions based on DT property, usable-memory-range")
Signed-off-by: default avatarYuntao Wang <yuntao.wang@linux.dev>
Link: https://patch.msgid.link/20251115134753.179931-4-yuntao.wang@linux.dev


Signed-off-by: default avatarRob Herring (Arm) <robh@kernel.org>
parent bec5f609

drivers/of/fdt.c

+11 −7
Original line number Diff line number Diff line
@@ -884,8 +884,9 @@ static unsigned long chosen_node_offset = -FDT_ERR_NOTFOUND; 
void __init early_init_dt_check_for_usable_mem_range(void)

{

	struct memblock_region rgn[MAX_USABLE_RANGES] = {0};

	const __be32 *prop, *endp;

	const __be32 *prop;

	int len, i;

	u64 base, size;

	unsigned long node = chosen_node_offset;



	if ((long)node < 0)
@@ -893,14 +894,17 @@ void __init early_init_dt_check_for_usable_mem_range(void) 


	pr_debug("Looking for usable-memory-range property... ");



	prop = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len);

	if (!prop || (len % (dt_root_addr_cells + dt_root_size_cells)))

	prop = of_flat_dt_get_addr_size_prop(node, "linux,usable-memory-range",

					     &len);

	if (!prop)

		return;



	endp = prop + (len / sizeof(__be32));

	for (i = 0; i < MAX_USABLE_RANGES && prop < endp; i++) {

		rgn[i].base = dt_mem_next_cell(dt_root_addr_cells, &prop);

		rgn[i].size = dt_mem_next_cell(dt_root_size_cells, &prop);

	len = min(len, MAX_USABLE_RANGES);



	for (i = 0; i < len; i++) {

		of_flat_dt_read_addr_size(prop, i, &base, &size);

		rgn[i].base = base;

		rgn[i].size = size;



		pr_debug("cap_mem_regions[%d]: base=%pa, size=%pa\n",

			 i, &rgn[i].base, &rgn[i].size);