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Merge branch 'for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / sys_x86_64.c
1 #include <linux/errno.h>
2 #include <linux/sched.h>
3 #include <linux/sched/mm.h>
4 #include <linux/syscalls.h>
5 #include <linux/mm.h>
6 #include <linux/fs.h>
7 #include <linux/smp.h>
8 #include <linux/sem.h>
9 #include <linux/msg.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>
19
20 #include <asm/elf.h>
21 #include <asm/compat.h>
22 #include <asm/ia32.h>
23 #include <asm/syscalls.h>
24
25 /*
26 * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
27 */
28 static unsigned long get_align_mask(void)
29 {
30 /* handle 32- and 64-bit case with a single conditional */
31 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
32 return 0;
33
34 if (!(current->flags & PF_RANDOMIZE))
35 return 0;
36
37 return va_align.mask;
38 }
39
40 /*
41 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the
42 * va_align.bits, [12:upper_bit), are set to a random value instead of
43 * zeroing them. This random value is computed once per boot. This form
44 * of ASLR is known as "per-boot ASLR".
45 *
46 * To achieve this, the random value is added to the info.align_offset
47 * value before calling vm_unmapped_area() or ORed directly to the
48 * address.
49 */
50 static unsigned long get_align_bits(void)
51 {
52 return va_align.bits & get_align_mask();
53 }
54
55 unsigned long align_vdso_addr(unsigned long addr)
56 {
57 unsigned long align_mask = get_align_mask();
58 addr = (addr + align_mask) & ~align_mask;
59 return addr | get_align_bits();
60 }
61
62 static int __init control_va_addr_alignment(char *str)
63 {
64 /* guard against enabling this on other CPU families */
65 if (va_align.flags < 0)
66 return 1;
67
68 if (*str == 0)
69 return 1;
70
71 if (*str == '=')
72 str++;
73
74 if (!strcmp(str, "32"))
75 va_align.flags = ALIGN_VA_32;
76 else if (!strcmp(str, "64"))
77 va_align.flags = ALIGN_VA_64;
78 else if (!strcmp(str, "off"))
79 va_align.flags = 0;
80 else if (!strcmp(str, "on"))
81 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
82 else
83 return 0;
84
85 return 1;
86 }
87 __setup("align_va_addr", control_va_addr_alignment);
88
89 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
90 unsigned long, prot, unsigned long, flags,
91 unsigned long, fd, unsigned long, off)
92 {
93 long error;
94 error = -EINVAL;
95 if (off & ~PAGE_MASK)
96 goto out;
97
98 error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
99 out:
100 return error;
101 }
102
103 static void find_start_end(unsigned long flags, unsigned long *begin,
104 unsigned long *end)
105 {
106 if (!in_compat_syscall() && (flags & MAP_32BIT)) {
107 /* This is usually used needed to map code in small
108 model, so it needs to be in the first 31bit. Limit
109 it to that. This means we need to move the
110 unmapped base down for this case. This can give
111 conflicts with the heap, but we assume that glibc
112 malloc knows how to fall back to mmap. Give it 1GB
113 of playground for now. -AK */
114 *begin = 0x40000000;
115 *end = 0x80000000;
116 if (current->flags & PF_RANDOMIZE) {
117 *begin = randomize_page(*begin, 0x02000000);
118 }
119 return;
120 }
121
122 *begin = get_mmap_base(1);
123 *end = in_compat_syscall() ? tasksize_32bit() : tasksize_64bit();
124 }
125
126 unsigned long
127 arch_get_unmapped_area(struct file *filp, unsigned long addr,
128 unsigned long len, unsigned long pgoff, unsigned long flags)
129 {
130 struct mm_struct *mm = current->mm;
131 struct vm_area_struct *vma;
132 struct vm_unmapped_area_info info;
133 unsigned long begin, end;
134
135 if (flags & MAP_FIXED)
136 return addr;
137
138 find_start_end(flags, &begin, &end);
139
140 if (len > end)
141 return -ENOMEM;
142
143 if (addr) {
144 addr = PAGE_ALIGN(addr);
145 vma = find_vma(mm, addr);
146 if (end - len >= addr &&
147 (!vma || addr + len <= vm_start_gap(vma)))
148 return addr;
149 }
150
151 info.flags = 0;
152 info.length = len;
153 info.low_limit = begin;
154 info.high_limit = end;
155 info.align_mask = 0;
156 info.align_offset = pgoff << PAGE_SHIFT;
157 if (filp) {
158 info.align_mask = get_align_mask();
159 info.align_offset += get_align_bits();
160 }
161 return vm_unmapped_area(&info);
162 }
163
164 unsigned long
165 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
166 const unsigned long len, const unsigned long pgoff,
167 const unsigned long flags)
168 {
169 struct vm_area_struct *vma;
170 struct mm_struct *mm = current->mm;
171 unsigned long addr = addr0;
172 struct vm_unmapped_area_info info;
173
174 /* requested length too big for entire address space */
175 if (len > TASK_SIZE)
176 return -ENOMEM;
177
178 if (flags & MAP_FIXED)
179 return addr;
180
181 /* for MAP_32BIT mappings we force the legacy mmap base */
182 if (!in_compat_syscall() && (flags & MAP_32BIT))
183 goto bottomup;
184
185 /* requesting a specific address */
186 if (addr) {
187 addr = PAGE_ALIGN(addr);
188 vma = find_vma(mm, addr);
189 if (TASK_SIZE - len >= addr &&
190 (!vma || addr + len <= vm_start_gap(vma)))
191 return addr;
192 }
193
194 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
195 info.length = len;
196 info.low_limit = PAGE_SIZE;
197 info.high_limit = get_mmap_base(0);
198 info.align_mask = 0;
199 info.align_offset = pgoff << PAGE_SHIFT;
200 if (filp) {
201 info.align_mask = get_align_mask();
202 info.align_offset += get_align_bits();
203 }
204 addr = vm_unmapped_area(&info);
205 if (!(addr & ~PAGE_MASK))
206 return addr;
207 VM_BUG_ON(addr != -ENOMEM);
208
209 bottomup:
210 /*
211 * A failed mmap() very likely causes application failure,
212 * so fall back to the bottom-up function here. This scenario
213 * can happen with large stack limits and large mmap()
214 * allocations.
215 */
216 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
217 }