1 #include <linux/errno.h>
2 #include <linux/sched.h>
3 #include <linux/sched/mm.h>
4 #include <linux/syscalls.h>
10 #include <linux/shm.h>
11 #include <linux/stat.h>
12 #include <linux/mman.h>
13 #include <linux/file.h>
14 #include <linux/utsname.h>
15 #include <linux/personality.h>
16 #include <linux/random.h>
17 #include <linux/uaccess.h>
18 #include <linux/elf.h>
21 #include <asm/compat.h>
23 #include <asm/syscalls.h>
27 * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
29 static unsigned long get_align_mask(void)
31 /* handle 32- and 64-bit case with a single conditional */
32 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
35 if (!(current->flags & PF_RANDOMIZE))
42 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the
43 * va_align.bits, [12:upper_bit), are set to a random value instead of
44 * zeroing them. This random value is computed once per boot. This form
45 * of ASLR is known as "per-boot ASLR".
47 * To achieve this, the random value is added to the info.align_offset
48 * value before calling vm_unmapped_area() or ORed directly to the
51 static unsigned long get_align_bits(void)
53 return va_align.bits & get_align_mask();
56 unsigned long align_vdso_addr(unsigned long addr)
58 unsigned long align_mask = get_align_mask();
59 addr = (addr + align_mask) & ~align_mask;
60 return addr | get_align_bits();
63 static int __init control_va_addr_alignment(char *str)
65 /* guard against enabling this on other CPU families */
66 if (va_align.flags < 0)
75 if (!strcmp(str, "32"))
76 va_align.flags = ALIGN_VA_32;
77 else if (!strcmp(str, "64"))
78 va_align.flags = ALIGN_VA_64;
79 else if (!strcmp(str, "off"))
81 else if (!strcmp(str, "on"))
82 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
88 __setup("align_va_addr", control_va_addr_alignment);
90 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
91 unsigned long, prot, unsigned long, flags,
92 unsigned long, fd, unsigned long, off)
99 error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
104 static void find_start_end(unsigned long addr, unsigned long flags,
105 unsigned long *begin, unsigned long *end)
107 if (!in_compat_syscall() && (flags & MAP_32BIT)) {
108 /* This is usually used needed to map code in small
109 model, so it needs to be in the first 31bit. Limit
110 it to that. This means we need to move the
111 unmapped base down for this case. This can give
112 conflicts with the heap, but we assume that glibc
113 malloc knows how to fall back to mmap. Give it 1GB
114 of playground for now. -AK */
117 if (current->flags & PF_RANDOMIZE) {
118 *begin = randomize_page(*begin, 0x02000000);
123 *begin = get_mmap_base(1);
124 if (in_compat_syscall())
125 *end = task_size_32bit();
127 *end = task_size_64bit(addr > DEFAULT_MAP_WINDOW);
131 arch_get_unmapped_area(struct file *filp, unsigned long addr,
132 unsigned long len, unsigned long pgoff, unsigned long flags)
134 struct mm_struct *mm = current->mm;
135 struct vm_area_struct *vma;
136 struct vm_unmapped_area_info info;
137 unsigned long begin, end;
139 addr = mpx_unmapped_area_check(addr, len, flags);
140 if (IS_ERR_VALUE(addr))
143 if (flags & MAP_FIXED)
146 find_start_end(addr, flags, &begin, &end);
152 addr = PAGE_ALIGN(addr);
153 vma = find_vma(mm, addr);
154 if (end - len >= addr &&
155 (!vma || addr + len <= vm_start_gap(vma)))
161 info.low_limit = begin;
162 info.high_limit = end;
164 info.align_offset = pgoff << PAGE_SHIFT;
166 info.align_mask = get_align_mask();
167 info.align_offset += get_align_bits();
169 return vm_unmapped_area(&info);
173 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
174 const unsigned long len, const unsigned long pgoff,
175 const unsigned long flags)
177 struct vm_area_struct *vma;
178 struct mm_struct *mm = current->mm;
179 unsigned long addr = addr0;
180 struct vm_unmapped_area_info info;
182 addr = mpx_unmapped_area_check(addr, len, flags);
183 if (IS_ERR_VALUE(addr))
186 /* requested length too big for entire address space */
190 if (flags & MAP_FIXED)
193 /* for MAP_32BIT mappings we force the legacy mmap base */
194 if (!in_compat_syscall() && (flags & MAP_32BIT))
197 /* requesting a specific address */
199 addr = PAGE_ALIGN(addr);
200 vma = find_vma(mm, addr);
201 if (TASK_SIZE - len >= addr &&
202 (!vma || addr + len <= vm_start_gap(vma)))
206 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
208 info.low_limit = PAGE_SIZE;
209 info.high_limit = get_mmap_base(0);
212 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
213 * in the full address space.
215 * !in_compat_syscall() check to avoid high addresses for x32.
217 if (addr > DEFAULT_MAP_WINDOW && !in_compat_syscall())
218 info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
221 info.align_offset = pgoff << PAGE_SHIFT;
223 info.align_mask = get_align_mask();
224 info.align_offset += get_align_bits();
226 addr = vm_unmapped_area(&info);
227 if (!(addr & ~PAGE_MASK))
229 VM_BUG_ON(addr != -ENOMEM);
233 * A failed mmap() very likely causes application failure,
234 * so fall back to the bottom-up function here. This scenario
235 * can happen with large stack limits and large mmap()
238 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags);