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/mm.h> 11 #include <linux/types.h> 12 13 #include <asm/cpufeature.h> 14 #include <asm/page.h> 15 16 /* 17 * You really shouldn't be using read() or write() on /dev/mem. This might go 18 * away in the future. 19 */ 20 int valid_phys_addr_range(phys_addr_t addr, size_t size) 21 { 22 /* 23 * Check whether addr is covered by a memory region without the 24 * MEMBLOCK_NOMAP attribute, and whether that region covers the 25 * entire range. In theory, this could lead to false negatives 26 * if the range is covered by distinct but adjacent memory regions 27 * that only differ in other attributes. However, few of such 28 * attributes have been defined, and it is debatable whether it 29 * follows that /dev/mem read() calls should be able traverse 30 * such boundaries. 31 */ 32 return memblock_is_region_memory(addr, size) && 33 memblock_is_map_memory(addr); 34 } 35 36 /* 37 * Do not allow /dev/mem mappings beyond the supported physical range. 38 */ 39 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) 40 { 41 return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK); 42 } 43 44 static int __init adjust_protection_map(void) 45 { 46 /* 47 * With Enhanced PAN we can honour the execute-only permissions as 48 * there is no PAN override with such mappings. 49 */ 50 if (cpus_have_const_cap(ARM64_HAS_EPAN)) { 51 protection_map[VM_EXEC] = PAGE_EXECONLY; 52 protection_map[VM_EXEC | VM_SHARED] = PAGE_EXECONLY; 53 } 54 55 return 0; 56 } 57 arch_initcall(adjust_protection_map); 58 59 pgprot_t vm_get_page_prot(unsigned long vm_flags) 60 { 61 pteval_t prot = pgprot_val(protection_map[vm_flags & 62 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]); 63 64 if (vm_flags & VM_ARM64_BTI) 65 prot |= PTE_GP; 66 67 /* 68 * There are two conditions required for returning a Normal Tagged 69 * memory type: (1) the user requested it via PROT_MTE passed to 70 * mmap() or mprotect() and (2) the corresponding vma supports MTE. We 71 * register (1) as VM_MTE in the vma->vm_flags and (2) as 72 * VM_MTE_ALLOWED. Note that the latter can only be set during the 73 * mmap() call since mprotect() does not accept MAP_* flags. 74 * Checking for VM_MTE only is sufficient since arch_validate_flags() 75 * does not permit (VM_MTE & !VM_MTE_ALLOWED). 76 */ 77 if (vm_flags & VM_MTE) 78 prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED); 79 80 return __pgprot(prot); 81 } 82 EXPORT_SYMBOL(vm_get_page_prot); 83