bootmem.c revision 92aa63a5a1bf2e7b0c79e6716d24b76dbbdcf951 
1/*
2 *  linux/mm/bootmem.c
3 *
4 *  Copyright (C) 1999 Ingo Molnar
5 *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
6 *
7 *  simple boot-time physical memory area allocator and
8 *  free memory collector. It's used to deal with reserved
9 *  system memory and memory holes as well.
10 */
11
12#include <linux/mm.h>
13#include <linux/kernel_stat.h>
14#include <linux/swap.h>
15#include <linux/interrupt.h>
16#include <linux/init.h>
17#include <linux/bootmem.h>
18#include <linux/mmzone.h>
19#include <linux/module.h>
20#include <asm/dma.h>
21#include <asm/io.h>
22#include "internal.h"
23
24/*
25 * Access to this subsystem has to be serialized externally. (this is
26 * true for the boot process anyway)
27 */
28unsigned long max_low_pfn;
29unsigned long min_low_pfn;
30unsigned long max_pfn;
31
32EXPORT_SYMBOL(max_pfn);		/* This is exported so
33				 * dma_get_required_mask(), which uses
34				 * it, can be an inline function */
35
36#ifdef CONFIG_CRASH_DUMP
37/*
38 * If we have booted due to a crash, max_pfn will be a very low value. We need
39 * to know the amount of memory that the previous kernel used.
40 */
41unsigned long saved_max_pfn;
42#endif
43
44/* return the number of _pages_ that will be allocated for the boot bitmap */
45unsigned long __init bootmem_bootmap_pages (unsigned long pages)
46{
47	unsigned long mapsize;
48
49	mapsize = (pages+7)/8;
50	mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;
51	mapsize >>= PAGE_SHIFT;
52
53	return mapsize;
54}
55
56/*
57 * Called once to set up the allocator itself.
58 */
59static unsigned long __init init_bootmem_core (pg_data_t *pgdat,
60	unsigned long mapstart, unsigned long start, unsigned long end)
61{
62	bootmem_data_t *bdata = pgdat->bdata;
63	unsigned long mapsize = ((end - start)+7)/8;
64
65	pgdat->pgdat_next = pgdat_list;
66	pgdat_list = pgdat;
67
68	mapsize = (mapsize + (sizeof(long) - 1UL)) & ~(sizeof(long) - 1UL);
69	bdata->node_bootmem_map = phys_to_virt(mapstart << PAGE_SHIFT);
70	bdata->node_boot_start = (start << PAGE_SHIFT);
71	bdata->node_low_pfn = end;
72
73	/*
74	 * Initially all pages are reserved - setup_arch() has to
75	 * register free RAM areas explicitly.
76	 */
77	memset(bdata->node_bootmem_map, 0xff, mapsize);
78
79	return mapsize;
80}
81
82/*
83 * Marks a particular physical memory range as unallocatable. Usable RAM
84 * might be used for boot-time allocations - or it might get added
85 * to the free page pool later on.
86 */
87static void __init reserve_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
88{
89	unsigned long i;
90	/*
91	 * round up, partially reserved pages are considered
92	 * fully reserved.
93	 */
94	unsigned long sidx = (addr - bdata->node_boot_start)/PAGE_SIZE;
95	unsigned long eidx = (addr + size - bdata->node_boot_start +
96							PAGE_SIZE-1)/PAGE_SIZE;
97	unsigned long end = (addr + size + PAGE_SIZE-1)/PAGE_SIZE;
98
99	BUG_ON(!size);
100	BUG_ON(sidx >= eidx);
101	BUG_ON((addr >> PAGE_SHIFT) >= bdata->node_low_pfn);
102	BUG_ON(end > bdata->node_low_pfn);
103
104	for (i = sidx; i < eidx; i++)
105		if (test_and_set_bit(i, bdata->node_bootmem_map)) {
106#ifdef CONFIG_DEBUG_BOOTMEM
107			printk("hm, page %08lx reserved twice.\n", i*PAGE_SIZE);
108#endif
109		}
110}
111
112static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
113{
114	unsigned long i;
115	unsigned long start;
116	/*
117	 * round down end of usable mem, partially free pages are
118	 * considered reserved.
119	 */
120	unsigned long sidx;
121	unsigned long eidx = (addr + size - bdata->node_boot_start)/PAGE_SIZE;
122	unsigned long end = (addr + size)/PAGE_SIZE;
123
124	BUG_ON(!size);
125	BUG_ON(end > bdata->node_low_pfn);
126
127	if (addr < bdata->last_success)
128		bdata->last_success = addr;
129
130	/*
131	 * Round up the beginning of the address.
132	 */
133	start = (addr + PAGE_SIZE-1) / PAGE_SIZE;
134	sidx = start - (bdata->node_boot_start/PAGE_SIZE);
135
136	for (i = sidx; i < eidx; i++) {
137		if (unlikely(!test_and_clear_bit(i, bdata->node_bootmem_map)))
138			BUG();
139	}
140}
141
142/*
143 * We 'merge' subsequent allocations to save space. We might 'lose'
144 * some fraction of a page if allocations cannot be satisfied due to
145 * size constraints on boxes where there is physical RAM space
146 * fragmentation - in these cases (mostly large memory boxes) this
147 * is not a problem.
148 *
149 * On low memory boxes we get it right in 100% of the cases.
150 *
151 * alignment has to be a power of 2 value.
152 *
153 * NOTE:  This function is _not_ reentrant.
154 */
155static void * __init
156__alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
157		unsigned long align, unsigned long goal)
158{
159	unsigned long offset, remaining_size, areasize, preferred;
160	unsigned long i, start = 0, incr, eidx;
161	void *ret;
162
163	if(!size) {
164		printk("__alloc_bootmem_core(): zero-sized request\n");
165		BUG();
166	}
167	BUG_ON(align & (align-1));
168
169	eidx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
170	offset = 0;
171	if (align &&
172	    (bdata->node_boot_start & (align - 1UL)) != 0)
173		offset = (align - (bdata->node_boot_start & (align - 1UL)));
174	offset >>= PAGE_SHIFT;
175
176	/*
177	 * We try to allocate bootmem pages above 'goal'
178	 * first, then we try to allocate lower pages.
179	 */
180	if (goal && (goal >= bdata->node_boot_start) &&
181	    ((goal >> PAGE_SHIFT) < bdata->node_low_pfn)) {
182		preferred = goal - bdata->node_boot_start;
183
184		if (bdata->last_success >= preferred)
185			preferred = bdata->last_success;
186	} else
187		preferred = 0;
188
189	preferred = ((preferred + align - 1) & ~(align - 1)) >> PAGE_SHIFT;
190	preferred += offset;
191	areasize = (size+PAGE_SIZE-1)/PAGE_SIZE;
192	incr = align >> PAGE_SHIFT ? : 1;
193
194restart_scan:
195	for (i = preferred; i < eidx; i += incr) {
196		unsigned long j;
197		i = find_next_zero_bit(bdata->node_bootmem_map, eidx, i);
198		i = ALIGN(i, incr);
199		if (test_bit(i, bdata->node_bootmem_map))
200			continue;
201		for (j = i + 1; j < i + areasize; ++j) {
202			if (j >= eidx)
203				goto fail_block;
204			if (test_bit (j, bdata->node_bootmem_map))
205				goto fail_block;
206		}
207		start = i;
208		goto found;
209	fail_block:
210		i = ALIGN(j, incr);
211	}
212
213	if (preferred > offset) {
214		preferred = offset;
215		goto restart_scan;
216	}
217	return NULL;
218
219found:
220	bdata->last_success = start << PAGE_SHIFT;
221	BUG_ON(start >= eidx);
222
223	/*
224	 * Is the next page of the previous allocation-end the start
225	 * of this allocation's buffer? If yes then we can 'merge'
226	 * the previous partial page with this allocation.
227	 */
228	if (align < PAGE_SIZE &&
229	    bdata->last_offset && bdata->last_pos+1 == start) {
230		offset = (bdata->last_offset+align-1) & ~(align-1);
231		BUG_ON(offset > PAGE_SIZE);
232		remaining_size = PAGE_SIZE-offset;
233		if (size < remaining_size) {
234			areasize = 0;
235			/* last_pos unchanged */
236			bdata->last_offset = offset+size;
237			ret = phys_to_virt(bdata->last_pos*PAGE_SIZE + offset +
238						bdata->node_boot_start);
239		} else {
240			remaining_size = size - remaining_size;
241			areasize = (remaining_size+PAGE_SIZE-1)/PAGE_SIZE;
242			ret = phys_to_virt(bdata->last_pos*PAGE_SIZE + offset +
243						bdata->node_boot_start);
244			bdata->last_pos = start+areasize-1;
245			bdata->last_offset = remaining_size;
246		}
247		bdata->last_offset &= ~PAGE_MASK;
248	} else {
249		bdata->last_pos = start + areasize - 1;
250		bdata->last_offset = size & ~PAGE_MASK;
251		ret = phys_to_virt(start * PAGE_SIZE + bdata->node_boot_start);
252	}
253
254	/*
255	 * Reserve the area now:
256	 */
257	for (i = start; i < start+areasize; i++)
258		if (unlikely(test_and_set_bit(i, bdata->node_bootmem_map)))
259			BUG();
260	memset(ret, 0, size);
261	return ret;
262}
263
264static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
265{
266	struct page *page;
267	unsigned long pfn;
268	bootmem_data_t *bdata = pgdat->bdata;
269	unsigned long i, count, total = 0;
270	unsigned long idx;
271	unsigned long *map;
272	int gofast = 0;
273
274	BUG_ON(!bdata->node_bootmem_map);
275
276	count = 0;
277	/* first extant page of the node */
278	pfn = bdata->node_boot_start >> PAGE_SHIFT;
279	idx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
280	map = bdata->node_bootmem_map;
281	/* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */
282	if (bdata->node_boot_start == 0 ||
283	    ffs(bdata->node_boot_start) - PAGE_SHIFT > ffs(BITS_PER_LONG))
284		gofast = 1;
285	for (i = 0; i < idx; ) {
286		unsigned long v = ~map[i / BITS_PER_LONG];
287
288		if (gofast && v == ~0UL) {
289			int j, order;
290
291			page = pfn_to_page(pfn);
292			count += BITS_PER_LONG;
293			__ClearPageReserved(page);
294			order = ffs(BITS_PER_LONG) - 1;
295			set_page_refs(page, order);
296			for (j = 1; j < BITS_PER_LONG; j++) {
297				if (j + 16 < BITS_PER_LONG)
298					prefetchw(page + j + 16);
299				__ClearPageReserved(page + j);
300			}
301			__free_pages(page, order);
302			i += BITS_PER_LONG;
303			page += BITS_PER_LONG;
304		} else if (v) {
305			unsigned long m;
306
307			page = pfn_to_page(pfn);
308			for (m = 1; m && i < idx; m<<=1, page++, i++) {
309				if (v & m) {
310					count++;
311					__ClearPageReserved(page);
312					set_page_refs(page, 0);
313					__free_page(page);
314				}
315			}
316		} else {
317			i+=BITS_PER_LONG;
318		}
319		pfn += BITS_PER_LONG;
320	}
321	total += count;
322
323	/*
324	 * Now free the allocator bitmap itself, it's not
325	 * needed anymore:
326	 */
327	page = virt_to_page(bdata->node_bootmem_map);
328	count = 0;
329	for (i = 0; i < ((bdata->node_low_pfn-(bdata->node_boot_start >> PAGE_SHIFT))/8 + PAGE_SIZE-1)/PAGE_SIZE; i++,page++) {
330		count++;
331		__ClearPageReserved(page);
332		set_page_count(page, 1);
333		__free_page(page);
334	}
335	total += count;
336	bdata->node_bootmem_map = NULL;
337
338	return total;
339}
340
341unsigned long __init init_bootmem_node (pg_data_t *pgdat, unsigned long freepfn, unsigned long startpfn, unsigned long endpfn)
342{
343	return(init_bootmem_core(pgdat, freepfn, startpfn, endpfn));
344}
345
346void __init reserve_bootmem_node (pg_data_t *pgdat, unsigned long physaddr, unsigned long size)
347{
348	reserve_bootmem_core(pgdat->bdata, physaddr, size);
349}
350
351void __init free_bootmem_node (pg_data_t *pgdat, unsigned long physaddr, unsigned long size)
352{
353	free_bootmem_core(pgdat->bdata, physaddr, size);
354}
355
356unsigned long __init free_all_bootmem_node (pg_data_t *pgdat)
357{
358	return(free_all_bootmem_core(pgdat));
359}
360
361unsigned long __init init_bootmem (unsigned long start, unsigned long pages)
362{
363	max_low_pfn = pages;
364	min_low_pfn = start;
365	return(init_bootmem_core(NODE_DATA(0), start, 0, pages));
366}
367
368#ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
369void __init reserve_bootmem (unsigned long addr, unsigned long size)
370{
371	reserve_bootmem_core(NODE_DATA(0)->bdata, addr, size);
372}
373#endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */
374
375void __init free_bootmem (unsigned long addr, unsigned long size)
376{
377	free_bootmem_core(NODE_DATA(0)->bdata, addr, size);
378}
379
380unsigned long __init free_all_bootmem (void)
381{
382	return(free_all_bootmem_core(NODE_DATA(0)));
383}
384
385void * __init __alloc_bootmem (unsigned long size, unsigned long align, unsigned long goal)
386{
387	pg_data_t *pgdat = pgdat_list;
388	void *ptr;
389
390	for_each_pgdat(pgdat)
391		if ((ptr = __alloc_bootmem_core(pgdat->bdata, size,
392						align, goal)))
393			return(ptr);
394
395	/*
396	 * Whoops, we cannot satisfy the allocation request.
397	 */
398	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
399	panic("Out of memory");
400	return NULL;
401}
402
403void * __init __alloc_bootmem_node (pg_data_t *pgdat, unsigned long size, unsigned long align, unsigned long goal)
404{
405	void *ptr;
406
407	ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal);
408	if (ptr)
409		return (ptr);
410
411	return __alloc_bootmem(size, align, goal);
412}
413
414