1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/arch/arm/mm/mmap.c 4 */ 5 #include <linux/fs.h> 6 #include <linux/mm.h> 7 #include <linux/mman.h> 8 #include <linux/shm.h> 9 #include <linux/sched/signal.h> 10 #include <linux/sched/mm.h> 11 #include <linux/io.h> 12 #include <linux/personality.h> 13 #include <linux/random.h> 14 #include <asm/cachetype.h> 15 16 #define COLOUR_ALIGN(addr,pgoff) \ 17 ((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \ 18 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1))) 19 20 /* 21 * We need to ensure that shared mappings are correctly aligned to 22 * avoid aliasing issues with VIPT caches. We need to ensure that 23 * a specific page of an object is always mapped at a multiple of 24 * SHMLBA bytes. 25 * 26 * We unconditionally provide this function for all cases, however 27 * in the VIVT case, we optimise out the alignment rules. 28 */ 29 unsigned long 30 arch_get_unmapped_area(struct file *filp, unsigned long addr, 31 unsigned long len, unsigned long pgoff, unsigned long flags) 32 { 33 struct mm_struct *mm = current->mm; 34 struct vm_area_struct *vma; 35 int do_align = 0; 36 int aliasing = cache_is_vipt_aliasing(); 37 struct vm_unmapped_area_info info = {}; 38 39 /* 40 * We only need to do colour alignment if either the I or D 41 * caches alias. 42 */ 43 if (aliasing) 44 do_align = filp || (flags & MAP_SHARED); 45 46 /* 47 * We enforce the MAP_FIXED case. 48 */ 49 if (flags & MAP_FIXED) { 50 if (aliasing && flags & MAP_SHARED && 51 (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)) 52 return -EINVAL; 53 return addr; 54 } 55 56 if (len > TASK_SIZE) 57 return -ENOMEM; 58 59 if (addr) { 60 if (do_align) 61 addr = COLOUR_ALIGN(addr, pgoff); 62 else 63 addr = PAGE_ALIGN(addr); 64 65 vma = find_vma(mm, addr); 66 if (TASK_SIZE - len >= addr && 67 (!vma || addr + len <= vm_start_gap(vma))) 68 return addr; 69 } 70 71 info.length = len; 72 info.low_limit = mm->mmap_base; 73 info.high_limit = TASK_SIZE; 74 info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0; 75 info.align_offset = pgoff << PAGE_SHIFT; 76 return vm_unmapped_area(&info); 77 } 78 79 unsigned long 80 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 81 const unsigned long len, const unsigned long pgoff, 82 const unsigned long flags) 83 { 84 struct vm_area_struct *vma; 85 struct mm_struct *mm = current->mm; 86 unsigned long addr = addr0; 87 int do_align = 0; 88 int aliasing = cache_is_vipt_aliasing(); 89 struct vm_unmapped_area_info info = {}; 90 91 /* 92 * We only need to do colour alignment if either the I or D 93 * caches alias. 94 */ 95 if (aliasing) 96 do_align = filp || (flags & MAP_SHARED); 97 98 /* requested length too big for entire address space */ 99 if (len > TASK_SIZE) 100 return -ENOMEM; 101 102 if (flags & MAP_FIXED) { 103 if (aliasing && flags & MAP_SHARED && 104 (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)) 105 return -EINVAL; 106 return addr; 107 } 108 109 /* requesting a specific address */ 110 if (addr) { 111 if (do_align) 112 addr = COLOUR_ALIGN(addr, pgoff); 113 else 114 addr = PAGE_ALIGN(addr); 115 vma = find_vma(mm, addr); 116 if (TASK_SIZE - len >= addr && 117 (!vma || addr + len <= vm_start_gap(vma))) 118 return addr; 119 } 120 121 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 122 info.length = len; 123 info.low_limit = FIRST_USER_ADDRESS; 124 info.high_limit = mm->mmap_base; 125 info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0; 126 info.align_offset = pgoff << PAGE_SHIFT; 127 addr = vm_unmapped_area(&info); 128 129 /* 130 * A failed mmap() very likely causes application failure, 131 * so fall back to the bottom-up function here. This scenario 132 * can happen with large stack limits and large mmap() 133 * allocations. 134 */ 135 if (addr & ~PAGE_MASK) { 136 VM_BUG_ON(addr != -ENOMEM); 137 info.flags = 0; 138 info.low_limit = mm->mmap_base; 139 info.high_limit = TASK_SIZE; 140 addr = vm_unmapped_area(&info); 141 } 142 143 return addr; 144 } 145 146 /* 147 * You really shouldn't be using read() or write() on /dev/mem. This 148 * might go away in the future. 149 */ 150 int valid_phys_addr_range(phys_addr_t addr, size_t size) 151 { 152 if (addr < PHYS_OFFSET) 153 return 0; 154 if (addr + size > __pa(high_memory - 1) + 1) 155 return 0; 156 157 return 1; 158 } 159 160 /* 161 * Do not allow /dev/mem mappings beyond the supported physical range. 162 */ 163 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) 164 { 165 return (pfn + (size >> PAGE_SHIFT)) <= (1 + (PHYS_MASK >> PAGE_SHIFT)); 166 } 167