1 /* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Copyright (C) 2011 Wind River Systems, 7 * written by Ralf Baechle <ralf@linux-mips.org> 8 */ 9 #include <linux/compiler.h> 10 #include <linux/elf-randomize.h> 11 #include <linux/errno.h> 12 #include <linux/mm.h> 13 #include <linux/mman.h> 14 #include <linux/export.h> 15 #include <linux/personality.h> 16 #include <linux/random.h> 17 #include <linux/sched/signal.h> 18 #include <linux/sched/mm.h> 19 20 unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */ 21 EXPORT_SYMBOL(shm_align_mask); 22 23 #define COLOUR_ALIGN(addr, pgoff) \ 24 ((((addr) + shm_align_mask) & ~shm_align_mask) + \ 25 (((pgoff) << PAGE_SHIFT) & shm_align_mask)) 26 27 enum mmap_allocation_direction {UP, DOWN}; 28 29 static unsigned long arch_get_unmapped_area_common(struct file *filp, 30 unsigned long addr0, unsigned long len, unsigned long pgoff, 31 unsigned long flags, enum mmap_allocation_direction dir) 32 { 33 struct mm_struct *mm = current->mm; 34 struct vm_area_struct *vma; 35 unsigned long addr = addr0; 36 int do_color_align; 37 struct vm_unmapped_area_info info = {}; 38 39 if (unlikely(len > TASK_SIZE)) 40 return -ENOMEM; 41 42 if (flags & MAP_FIXED) { 43 /* Even MAP_FIXED mappings must reside within TASK_SIZE */ 44 if (TASK_SIZE - len < addr) 45 return -EINVAL; 46 47 /* 48 * We do not accept a shared mapping if it would violate 49 * cache aliasing constraints. 50 */ 51 if ((flags & MAP_SHARED) && 52 ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask)) 53 return -EINVAL; 54 return addr; 55 } 56 57 do_color_align = 0; 58 if (filp || (flags & MAP_SHARED)) 59 do_color_align = 1; 60 61 /* requesting a specific address */ 62 if (addr) { 63 if (do_color_align) 64 addr = COLOUR_ALIGN(addr, pgoff); 65 else 66 addr = PAGE_ALIGN(addr); 67 68 vma = find_vma(mm, addr); 69 if (TASK_SIZE - len >= addr && 70 (!vma || addr + len <= vm_start_gap(vma))) 71 return addr; 72 } 73 74 info.length = len; 75 info.align_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0; 76 info.align_offset = pgoff << PAGE_SHIFT; 77 78 if (dir == DOWN) { 79 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 80 info.low_limit = PAGE_SIZE; 81 info.high_limit = mm->mmap_base; 82 addr = vm_unmapped_area(&info); 83 84 if (!(addr & ~PAGE_MASK)) 85 return addr; 86 87 /* 88 * A failed mmap() very likely causes application failure, 89 * so fall back to the bottom-up function here. This scenario 90 * can happen with large stack limits and large mmap() 91 * allocations. 92 */ 93 } 94 95 info.low_limit = mm->mmap_base; 96 info.high_limit = TASK_SIZE; 97 return vm_unmapped_area(&info); 98 } 99 100 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0, 101 unsigned long len, unsigned long pgoff, unsigned long flags) 102 { 103 return arch_get_unmapped_area_common(filp, 104 addr0, len, pgoff, flags, UP); 105 } 106 107 /* 108 * There is no need to export this but sched.h declares the function as 109 * extern so making it static here results in an error. 110 */ 111 unsigned long arch_get_unmapped_area_topdown(struct file *filp, 112 unsigned long addr0, unsigned long len, unsigned long pgoff, 113 unsigned long flags) 114 { 115 return arch_get_unmapped_area_common(filp, 116 addr0, len, pgoff, flags, DOWN); 117 } 118 119 bool __virt_addr_valid(const volatile void *kaddr) 120 { 121 unsigned long vaddr = (unsigned long)kaddr; 122 123 if ((vaddr < PAGE_OFFSET) || (vaddr >= MAP_BASE)) 124 return false; 125 126 return pfn_valid(PFN_DOWN(virt_to_phys(kaddr))); 127 } 128 EXPORT_SYMBOL_GPL(__virt_addr_valid); 129