1 #include <linux/errno.h> 2 #include <linux/sched.h> 3 #include <linux/syscalls.h> 4 #include <linux/mm.h> 5 #include <linux/fs.h> 6 #include <linux/smp.h> 7 #include <linux/sem.h> 8 #include <linux/msg.h> 9 #include <linux/shm.h> 10 #include <linux/stat.h> 11 #include <linux/mman.h> 12 #include <linux/file.h> 13 #include <linux/utsname.h> 14 #include <linux/personality.h> 15 #include <linux/random.h> 16 #include <linux/uaccess.h> 17 #include <linux/elf.h> 18 19 #include <asm/ia32.h> 20 #include <asm/syscalls.h> 21 22 /* 23 * Align a virtual address to avoid aliasing in the I$ on AMD F15h. 24 */ 25 static unsigned long get_align_mask(void) 26 { 27 /* handle 32- and 64-bit case with a single conditional */ 28 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32()))) 29 return 0; 30 31 if (!(current->flags & PF_RANDOMIZE)) 32 return 0; 33 34 return va_align.mask; 35 } 36 37 /* 38 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the 39 * va_align.bits, [12:upper_bit), are set to a random value instead of 40 * zeroing them. This random value is computed once per boot. This form 41 * of ASLR is known as "per-boot ASLR". 42 * 43 * To achieve this, the random value is added to the info.align_offset 44 * value before calling vm_unmapped_area() or ORed directly to the 45 * address. 46 */ 47 static unsigned long get_align_bits(void) 48 { 49 return va_align.bits & get_align_mask(); 50 } 51 52 unsigned long align_vdso_addr(unsigned long addr) 53 { 54 unsigned long align_mask = get_align_mask(); 55 addr = (addr + align_mask) & ~align_mask; 56 return addr | get_align_bits(); 57 } 58 59 static int __init control_va_addr_alignment(char *str) 60 { 61 /* guard against enabling this on other CPU families */ 62 if (va_align.flags < 0) 63 return 1; 64 65 if (*str == 0) 66 return 1; 67 68 if (*str == '=') 69 str++; 70 71 if (!strcmp(str, "32")) 72 va_align.flags = ALIGN_VA_32; 73 else if (!strcmp(str, "64")) 74 va_align.flags = ALIGN_VA_64; 75 else if (!strcmp(str, "off")) 76 va_align.flags = 0; 77 else if (!strcmp(str, "on")) 78 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64; 79 else 80 return 0; 81 82 return 1; 83 } 84 __setup("align_va_addr", control_va_addr_alignment); 85 86 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len, 87 unsigned long, prot, unsigned long, flags, 88 unsigned long, fd, unsigned long, off) 89 { 90 long error; 91 error = -EINVAL; 92 if (off & ~PAGE_MASK) 93 goto out; 94 95 error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT); 96 out: 97 return error; 98 } 99 100 static void find_start_end(unsigned long flags, unsigned long *begin, 101 unsigned long *end) 102 { 103 if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) { 104 unsigned long new_begin; 105 /* This is usually used needed to map code in small 106 model, so it needs to be in the first 31bit. Limit 107 it to that. This means we need to move the 108 unmapped base down for this case. This can give 109 conflicts with the heap, but we assume that glibc 110 malloc knows how to fall back to mmap. Give it 1GB 111 of playground for now. -AK */ 112 *begin = 0x40000000; 113 *end = 0x80000000; 114 if (current->flags & PF_RANDOMIZE) { 115 new_begin = randomize_range(*begin, *begin + 0x02000000, 0); 116 if (new_begin) 117 *begin = new_begin; 118 } 119 } else { 120 *begin = current->mm->mmap_legacy_base; 121 *end = TASK_SIZE; 122 } 123 } 124 125 unsigned long 126 arch_get_unmapped_area(struct file *filp, unsigned long addr, 127 unsigned long len, unsigned long pgoff, unsigned long flags) 128 { 129 struct mm_struct *mm = current->mm; 130 struct vm_area_struct *vma; 131 struct vm_unmapped_area_info info; 132 unsigned long begin, end; 133 134 if (flags & MAP_FIXED) 135 return addr; 136 137 find_start_end(flags, &begin, &end); 138 139 if (len > end) 140 return -ENOMEM; 141 142 if (addr) { 143 addr = PAGE_ALIGN(addr); 144 vma = find_vma(mm, addr); 145 if (end - len >= addr && 146 (!vma || addr + len <= vma->vm_start)) 147 return addr; 148 } 149 150 info.flags = 0; 151 info.length = len; 152 info.low_limit = begin; 153 info.high_limit = end; 154 info.align_mask = 0; 155 info.align_offset = pgoff << PAGE_SHIFT; 156 if (filp) { 157 info.align_mask = get_align_mask(); 158 info.align_offset += get_align_bits(); 159 } 160 return vm_unmapped_area(&info); 161 } 162 163 unsigned long 164 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 165 const unsigned long len, const unsigned long pgoff, 166 const unsigned long flags) 167 { 168 struct vm_area_struct *vma; 169 struct mm_struct *mm = current->mm; 170 unsigned long addr = addr0; 171 struct vm_unmapped_area_info info; 172 173 /* requested length too big for entire address space */ 174 if (len > TASK_SIZE) 175 return -ENOMEM; 176 177 if (flags & MAP_FIXED) 178 return addr; 179 180 /* for MAP_32BIT mappings we force the legacy mmap base */ 181 if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) 182 goto bottomup; 183 184 /* requesting a specific address */ 185 if (addr) { 186 addr = PAGE_ALIGN(addr); 187 vma = find_vma(mm, addr); 188 if (TASK_SIZE - len >= addr && 189 (!vma || addr + len <= vma->vm_start)) 190 return addr; 191 } 192 193 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 194 info.length = len; 195 info.low_limit = PAGE_SIZE; 196 info.high_limit = mm->mmap_base; 197 info.align_mask = 0; 198 info.align_offset = pgoff << PAGE_SHIFT; 199 if (filp) { 200 info.align_mask = get_align_mask(); 201 info.align_offset += get_align_bits(); 202 } 203 addr = vm_unmapped_area(&info); 204 if (!(addr & ~PAGE_MASK)) 205 return addr; 206 VM_BUG_ON(addr != -ENOMEM); 207 208 bottomup: 209 /* 210 * A failed mmap() very likely causes application failure, 211 * so fall back to the bottom-up function here. This scenario 212 * can happen with large stack limits and large mmap() 213 * allocations. 214 */ 215 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 216 } 217