1 #include <linux/errno.h>
2 #include <linux/sched.h>
3 #include <linux/syscalls.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>
19 #include <asm/compat.h>
21 #include <asm/syscalls.h>
24 * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
26 static unsigned long get_align_mask(void)
28 /* handle 32- and 64-bit case with a single conditional */
29 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
32 if (!(current->flags & PF_RANDOMIZE))
39 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the
40 * va_align.bits, [12:upper_bit), are set to a random value instead of
41 * zeroing them. This random value is computed once per boot. This form
42 * of ASLR is known as "per-boot ASLR".
44 * To achieve this, the random value is added to the info.align_offset
45 * value before calling vm_unmapped_area() or ORed directly to the
48 static unsigned long get_align_bits(void)
50 return va_align.bits & get_align_mask();
53 unsigned long align_vdso_addr(unsigned long addr)
55 unsigned long align_mask = get_align_mask();
56 addr = (addr + align_mask) & ~align_mask;
57 return addr | get_align_bits();
60 static int __init control_va_addr_alignment(char *str)
62 /* guard against enabling this on other CPU families */
63 if (va_align.flags < 0)
69 if (!strcmp(str, "32"))
70 va_align.flags = ALIGN_VA_32;
71 else if (!strcmp(str, "64"))
72 va_align.flags = ALIGN_VA_64;
73 else if (!strcmp(str, "off"))
75 else if (!strcmp(str, "on"))
76 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
78 pr_warn("invalid option value: 'align_va_addr=%s'\n", str);
82 __setup("align_va_addr=", control_va_addr_alignment);
84 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
85 unsigned long, prot, unsigned long, flags,
86 unsigned long, fd, unsigned long, off)
93 error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
98 static void find_start_end(unsigned long flags, unsigned long *begin,
101 if (!in_compat_syscall() && (flags & MAP_32BIT)) {
102 /* This is usually used needed to map code in small
103 model, so it needs to be in the first 31bit. Limit
104 it to that. This means we need to move the
105 unmapped base down for this case. This can give
106 conflicts with the heap, but we assume that glibc
107 malloc knows how to fall back to mmap. Give it 1GB
108 of playground for now. -AK */
111 if (current->flags & PF_RANDOMIZE) {
112 *begin = randomize_page(*begin, 0x02000000);
115 *begin = current->mm->mmap_legacy_base;
121 arch_get_unmapped_area(struct file *filp, unsigned long addr,
122 unsigned long len, unsigned long pgoff, unsigned long flags)
124 struct mm_struct *mm = current->mm;
125 struct vm_area_struct *vma;
126 struct vm_unmapped_area_info info;
127 unsigned long begin, end;
129 if (flags & MAP_FIXED)
132 find_start_end(flags, &begin, &end);
138 addr = PAGE_ALIGN(addr);
139 vma = find_vma(mm, addr);
140 if (end - len >= addr &&
141 (!vma || addr + len <= vm_start_gap(vma)))
147 info.low_limit = begin;
148 info.high_limit = end;
150 info.align_offset = pgoff << PAGE_SHIFT;
152 info.align_mask = get_align_mask();
153 info.align_offset += get_align_bits();
155 return vm_unmapped_area(&info);
159 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
160 const unsigned long len, const unsigned long pgoff,
161 const unsigned long flags)
163 struct vm_area_struct *vma;
164 struct mm_struct *mm = current->mm;
165 unsigned long addr = addr0;
166 struct vm_unmapped_area_info info;
168 /* requested length too big for entire address space */
172 if (flags & MAP_FIXED)
175 /* for MAP_32BIT mappings we force the legacy mmap base */
176 if (!in_compat_syscall() && (flags & MAP_32BIT))
179 /* requesting a specific address */
181 addr = PAGE_ALIGN(addr);
182 vma = find_vma(mm, addr);
183 if (TASK_SIZE - len >= addr &&
184 (!vma || addr + len <= vm_start_gap(vma)))
188 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
190 info.low_limit = PAGE_SIZE;
191 info.high_limit = mm->mmap_base;
193 info.align_offset = pgoff << PAGE_SHIFT;
195 info.align_mask = get_align_mask();
196 info.align_offset += get_align_bits();
198 addr = vm_unmapped_area(&info);
199 if (!(addr & ~PAGE_MASK))
201 VM_BUG_ON(addr != -ENOMEM);
205 * A failed mmap() very likely causes application failure,
206 * so fall back to the bottom-up function here. This scenario
207 * can happen with large stack limits and large mmap()
210 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags);