From 463942de13cd30fad5dba709f708483eab7efc2c Mon Sep 17 00:00:00 2001 From: Yuntao Wang Date: Sat, 15 Nov 2025 21:47:48 +0800 Subject: [PATCH] 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: fb319e77a0e7 ("of: fdt: Add memory for devices by DT property "linux,usable-memory-range"") Fixes: 2af2b50acf9b9c38 ("of: fdt: Add generic support for handling usable memory range property") Fixes: 8f579b1c4e347b23 ("arm64: limit memory regions based on DT property, usable-memory-range") Signed-off-by: Yuntao Wang Link: https://patch.msgid.link/20251115134753.179931-4-yuntao.wang@linux.dev Signed-off-by: Rob Herring (Arm) --- drivers/of/fdt.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index b45f60dccd7cf..ea37ba694bcd7 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -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); -- 2.47.3