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 */
25static 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 */
47static unsigned long get_align_bits(void)
48{
49	return va_align.bits & get_align_mask();
50}
51
52unsigned 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
59static 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
86SYSCALL_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);
96out:
97	return error;
98}
99
100static 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
125unsigned long
126arch_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
163unsigned long
164arch_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
208bottomup:
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