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 static pgprot_t protection_map[16] __ro_after_init = { 17 [VM_NONE] = PAGE_NONE, 18 [VM_READ] = PAGE_READONLY, 19 [VM_WRITE] = PAGE_READONLY, 20 [VM_WRITE | VM_READ] = PAGE_READONLY, 21 /* PAGE_EXECONLY if Enhanced PAN */ 22 [VM_EXEC] = PAGE_READONLY_EXEC, 23 [VM_EXEC | VM_READ] = PAGE_READONLY_EXEC, 24 [VM_EXEC | VM_WRITE] = PAGE_READONLY_EXEC, 25 [VM_EXEC | VM_WRITE | VM_READ] = PAGE_READONLY_EXEC, 26 [VM_SHARED] = PAGE_NONE, 27 [VM_SHARED | VM_READ] = PAGE_READONLY, 28 [VM_SHARED | VM_WRITE] = PAGE_SHARED, 29 [VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED, 30 /* PAGE_EXECONLY if Enhanced PAN */ 31 [VM_SHARED | VM_EXEC] = PAGE_READONLY_EXEC, 32 [VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY_EXEC, 33 [VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED_EXEC, 34 [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_EXEC 35 }; 36 37 static ptdesc_t gcs_page_prot __ro_after_init = _PAGE_GCS_RO; 38 39 /* 40 * You really shouldn't be using read() or write() on /dev/mem. This might go 41 * away in the future. 42 */ 43 int valid_phys_addr_range(phys_addr_t addr, size_t size) 44 { 45 /* 46 * Check whether addr is covered by a memory region without the 47 * MEMBLOCK_NOMAP attribute, and whether that region covers the 48 * entire range. In theory, this could lead to false negatives 49 * if the range is covered by distinct but adjacent memory regions 50 * that only differ in other attributes. However, few of such 51 * attributes have been defined, and it is debatable whether it 52 * follows that /dev/mem read() calls should be able traverse 53 * such boundaries. 54 */ 55 return memblock_is_region_memory(addr, size) && 56 memblock_is_map_memory(addr); 57 } 58 59 /* 60 * Do not allow /dev/mem mappings beyond the supported physical range. 61 */ 62 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) 63 { 64 return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK); 65 } 66 67 static int __init adjust_protection_map(void) 68 { 69 /* 70 * With Enhanced PAN we can honour the execute-only permissions as 71 * there is no PAN override with such mappings. 72 */ 73 if (cpus_have_cap(ARM64_HAS_EPAN)) { 74 protection_map[VM_EXEC] = PAGE_EXECONLY; 75 protection_map[VM_EXEC | VM_SHARED] = PAGE_EXECONLY; 76 } 77 78 if (lpa2_is_enabled()) { 79 for (int i = 0; i < ARRAY_SIZE(protection_map); i++) 80 pgprot_val(protection_map[i]) &= ~PTE_SHARED; 81 gcs_page_prot &= ~PTE_SHARED; 82 } 83 84 return 0; 85 } 86 arch_initcall(adjust_protection_map); 87 88 pgprot_t vm_get_page_prot(vm_flags_t vm_flags) 89 { 90 ptdesc_t prot; 91 92 /* Short circuit GCS to avoid bloating the table. */ 93 if (system_supports_gcs() && (vm_flags & VM_SHADOW_STACK)) { 94 /* Honour mprotect(PROT_NONE) on shadow stack mappings */ 95 if (vm_flags & VM_ACCESS_FLAGS) 96 prot = gcs_page_prot; 97 else 98 prot = pgprot_val(protection_map[VM_NONE]); 99 } else { 100 prot = pgprot_val(protection_map[vm_flags & 101 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]); 102 } 103 104 if (vm_flags & VM_ARM64_BTI) 105 prot |= PTE_GP; 106 107 /* 108 * There are two conditions required for returning a Normal Tagged 109 * memory type: (1) the user requested it via PROT_MTE passed to 110 * mmap() or mprotect() and (2) the corresponding vma supports MTE. We 111 * register (1) as VM_MTE in the vma->vm_flags and (2) as 112 * VM_MTE_ALLOWED. Note that the latter can only be set during the 113 * mmap() call since mprotect() does not accept MAP_* flags. 114 * Checking for VM_MTE only is sufficient since arch_validate_flags() 115 * does not permit (VM_MTE & !VM_MTE_ALLOWED). 116 */ 117 if (vm_flags & VM_MTE) 118 prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED); 119 120 #ifdef CONFIG_ARCH_HAS_PKEYS 121 if (system_supports_poe()) { 122 if (vm_flags & VM_PKEY_BIT0) 123 prot |= PTE_PO_IDX_0; 124 if (vm_flags & VM_PKEY_BIT1) 125 prot |= PTE_PO_IDX_1; 126 if (vm_flags & VM_PKEY_BIT2) 127 prot |= PTE_PO_IDX_2; 128 } 129 #endif 130 131 return __pgprot(prot); 132 } 133 EXPORT_SYMBOL(vm_get_page_prot); 134