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.flags = 0; 72 info.length = len; 73 info.low_limit = mm->mmap_base; 74 info.high_limit = TASK_SIZE; 75 info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0; 76 info.align_offset = pgoff << PAGE_SHIFT; 77 return vm_unmapped_area(&info); 78 } 79 80 unsigned long 81 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 82 const unsigned long len, const unsigned long pgoff, 83 const unsigned long flags) 84 { 85 struct vm_area_struct *vma; 86 struct mm_struct *mm = current->mm; 87 unsigned long addr = addr0; 88 int do_align = 0; 89 int aliasing = cache_is_vipt_aliasing(); 90 struct vm_unmapped_area_info info; 91 92 /* 93 * We only need to do colour alignment if either the I or D 94 * caches alias. 95 */ 96 if (aliasing) 97 do_align = filp || (flags & MAP_SHARED); 98 99 /* requested length too big for entire address space */ 100 if (len > TASK_SIZE) 101 return -ENOMEM; 102 103 if (flags & MAP_FIXED) { 104 if (aliasing && flags & MAP_SHARED && 105 (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)) 106 return -EINVAL; 107 return addr; 108 } 109 110 /* requesting a specific address */ 111 if (addr) { 112 if (do_align) 113 addr = COLOUR_ALIGN(addr, pgoff); 114 else 115 addr = PAGE_ALIGN(addr); 116 vma = find_vma(mm, addr); 117 if (TASK_SIZE - len >= addr && 118 (!vma || addr + len <= vm_start_gap(vma))) 119 return addr; 120 } 121 122 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 123 info.length = len; 124 info.low_limit = FIRST_USER_ADDRESS; 125 info.high_limit = mm->mmap_base; 126 info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0; 127 info.align_offset = pgoff << PAGE_SHIFT; 128 addr = vm_unmapped_area(&info); 129 130 /* 131 * A failed mmap() very likely causes application failure, 132 * so fall back to the bottom-up function here. This scenario 133 * can happen with large stack limits and large mmap() 134 * allocations. 135 */ 136 if (addr & ~PAGE_MASK) { 137 VM_BUG_ON(addr != -ENOMEM); 138 info.flags = 0; 139 info.low_limit = mm->mmap_base; 140 info.high_limit = TASK_SIZE; 141 addr = vm_unmapped_area(&info); 142 } 143 144 return addr; 145 } 146 147 /* 148 * You really shouldn't be using read() or write() on /dev/mem. This 149 * might go away in the future. 150 */ 151 int valid_phys_addr_range(phys_addr_t addr, size_t size) 152 { 153 if (addr < PHYS_OFFSET) 154 return 0; 155 if (addr + size > __pa(high_memory - 1) + 1) 156 return 0; 157 158 return 1; 159 } 160 161 /* 162 * Do not allow /dev/mem mappings beyond the supported physical range. 163 */ 164 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) 165 { 166 return (pfn + (size >> PAGE_SHIFT)) <= (1 + (PHYS_MASK >> PAGE_SHIFT)); 167 } 168