1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Based on arch/arm/mm/mmap.c 4 * 5 * Copyright (C) 2012 ARM Ltd. 6 */ 7 8 #include <linux/io.h> 9 #include <linux/memblock.h> 10 #include <linux/types.h> 11 12 #include <asm/page.h> 13 14 /* 15 * You really shouldn't be using read() or write() on /dev/mem. This might go 16 * away in the future. 17 */ 18 int valid_phys_addr_range(phys_addr_t addr, size_t size) 19 { 20 /* 21 * Check whether addr is covered by a memory region without the 22 * MEMBLOCK_NOMAP attribute, and whether that region covers the 23 * entire range. In theory, this could lead to false negatives 24 * if the range is covered by distinct but adjacent memory regions 25 * that only differ in other attributes. However, few of such 26 * attributes have been defined, and it is debatable whether it 27 * follows that /dev/mem read() calls should be able traverse 28 * such boundaries. 29 */ 30 return memblock_is_region_memory(addr, size) && 31 memblock_is_map_memory(addr); 32 } 33 34 /* 35 * Do not allow /dev/mem mappings beyond the supported physical range. 36 */ 37 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) 38 { 39 return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK); 40 } 41