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 * @flags denotes the allocation direction - bottomup or topdown -
26 * or vDSO; see call sites below.
27 */
28unsigned long align_addr(unsigned long addr, struct file *filp,
29			 enum align_flags flags)
30{
31	unsigned long tmp_addr;
32
33	/* handle 32- and 64-bit case with a single conditional */
34	if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
35		return addr;
36
37	if (!(current->flags & PF_RANDOMIZE))
38		return addr;
39
40	if (!((flags & ALIGN_VDSO) || filp))
41		return addr;
42
43	tmp_addr = addr;
44
45	/*
46	 * We need an address which is <= than the original
47	 * one only when in topdown direction.
48	 */
49	if (!(flags & ALIGN_TOPDOWN))
50		tmp_addr += va_align.mask;
51
52	tmp_addr &= ~va_align.mask;
53
54	return tmp_addr;
55}
56
57static int __init control_va_addr_alignment(char *str)
58{
59	/* guard against enabling this on other CPU families */
60	if (va_align.flags < 0)
61		return 1;
62
63	if (*str == 0)
64		return 1;
65
66	if (*str == '=')
67		str++;
68
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"))
74		va_align.flags = 0;
75	else if (!strcmp(str, "on"))
76		va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
77	else
78		return 0;
79
80	return 1;
81}
82__setup("align_va_addr", control_va_addr_alignment);
83
84SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
85		unsigned long, prot, unsigned long, flags,
86		unsigned long, fd, unsigned long, off)
87{
88	long error;
89	error = -EINVAL;
90	if (off & ~PAGE_MASK)
91		goto out;
92
93	error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
94out:
95	return error;
96}
97
98static void find_start_end(unsigned long flags, unsigned long *begin,
99			   unsigned long *end)
100{
101	if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) {
102		unsigned long new_begin;
103		/* This is usually used needed to map code in small
104		   model, so it needs to be in the first 31bit. Limit
105		   it to that.  This means we need to move the
106		   unmapped base down for this case. This can give
107		   conflicts with the heap, but we assume that glibc
108		   malloc knows how to fall back to mmap. Give it 1GB
109		   of playground for now. -AK */
110		*begin = 0x40000000;
111		*end = 0x80000000;
112		if (current->flags & PF_RANDOMIZE) {
113			new_begin = randomize_range(*begin, *begin + 0x02000000, 0);
114			if (new_begin)
115				*begin = new_begin;
116		}
117	} else {
118		*begin = TASK_UNMAPPED_BASE;
119		*end = TASK_SIZE;
120	}
121}
122
123unsigned long
124arch_get_unmapped_area(struct file *filp, unsigned long addr,
125		unsigned long len, unsigned long pgoff, unsigned long flags)
126{
127	struct mm_struct *mm = current->mm;
128	struct vm_area_struct *vma;
129	unsigned long start_addr;
130	unsigned long begin, end;
131
132	if (flags & MAP_FIXED)
133		return addr;
134
135	find_start_end(flags, &begin, &end);
136
137	if (len > end)
138		return -ENOMEM;
139
140	if (addr) {
141		addr = PAGE_ALIGN(addr);
142		vma = find_vma(mm, addr);
143		if (end - len >= addr &&
144		    (!vma || addr + len <= vma->vm_start))
145			return addr;
146	}
147	if (((flags & MAP_32BIT) || test_thread_flag(TIF_ADDR32))
148	    && len <= mm->cached_hole_size) {
149		mm->cached_hole_size = 0;
150		mm->free_area_cache = begin;
151	}
152	addr = mm->free_area_cache;
153	if (addr < begin)
154		addr = begin;
155	start_addr = addr;
156
157full_search:
158
159	addr = align_addr(addr, filp, 0);
160
161	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
162		/* At this point:  (!vma || addr < vma->vm_end). */
163		if (end - len < addr) {
164			/*
165			 * Start a new search - just in case we missed
166			 * some holes.
167			 */
168			if (start_addr != begin) {
169				start_addr = addr = begin;
170				mm->cached_hole_size = 0;
171				goto full_search;
172			}
173			return -ENOMEM;
174		}
175		if (!vma || addr + len <= vma->vm_start) {
176			/*
177			 * Remember the place where we stopped the search:
178			 */
179			mm->free_area_cache = addr + len;
180			return addr;
181		}
182		if (addr + mm->cached_hole_size < vma->vm_start)
183			mm->cached_hole_size = vma->vm_start - addr;
184
185		addr = vma->vm_end;
186		addr = align_addr(addr, filp, 0);
187	}
188}
189
190
191unsigned long
192arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
193			  const unsigned long len, const unsigned long pgoff,
194			  const unsigned long flags)
195{
196	struct vm_area_struct *vma;
197	struct mm_struct *mm = current->mm;
198	unsigned long addr = addr0, start_addr;
199
200	/* requested length too big for entire address space */
201	if (len > TASK_SIZE)
202		return -ENOMEM;
203
204	if (flags & MAP_FIXED)
205		return addr;
206
207	/* for MAP_32BIT mappings we force the legact mmap base */
208	if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT))
209		goto bottomup;
210
211	/* requesting a specific address */
212	if (addr) {
213		addr = PAGE_ALIGN(addr);
214		vma = find_vma(mm, addr);
215		if (TASK_SIZE - len >= addr &&
216				(!vma || addr + len <= vma->vm_start))
217			return addr;
218	}
219
220	/* check if free_area_cache is useful for us */
221	if (len <= mm->cached_hole_size) {
222		mm->cached_hole_size = 0;
223		mm->free_area_cache = mm->mmap_base;
224	}
225
226try_again:
227	/* either no address requested or can't fit in requested address hole */
228	start_addr = addr = mm->free_area_cache;
229
230	if (addr < len)
231		goto fail;
232
233	addr -= len;
234	do {
235		addr = align_addr(addr, filp, ALIGN_TOPDOWN);
236
237		/*
238		 * Lookup failure means no vma is above this address,
239		 * else if new region fits below vma->vm_start,
240		 * return with success:
241		 */
242		vma = find_vma(mm, addr);
243		if (!vma || addr+len <= vma->vm_start)
244			/* remember the address as a hint for next time */
245			return mm->free_area_cache = addr;
246
247		/* remember the largest hole we saw so far */
248		if (addr + mm->cached_hole_size < vma->vm_start)
249			mm->cached_hole_size = vma->vm_start - addr;
250
251		/* try just below the current vma->vm_start */
252		addr = vma->vm_start-len;
253	} while (len < vma->vm_start);
254
255fail:
256	/*
257	 * if hint left us with no space for the requested
258	 * mapping then try again:
259	 */
260	if (start_addr != mm->mmap_base) {
261		mm->free_area_cache = mm->mmap_base;
262		mm->cached_hole_size = 0;
263		goto try_again;
264	}
265
266bottomup:
267	/*
268	 * A failed mmap() very likely causes application failure,
269	 * so fall back to the bottom-up function here. This scenario
270	 * can happen with large stack limits and large mmap()
271	 * allocations.
272	 */
273	mm->cached_hole_size = ~0UL;
274	mm->free_area_cache = TASK_UNMAPPED_BASE;
275	addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
276	/*
277	 * Restore the topdown base:
278	 */
279	mm->free_area_cache = mm->mmap_base;
280	mm->cached_hole_size = ~0UL;
281
282	return addr;
283}
284