bootmem.c revision 5a982cbc7b3fe6cf72266f319286f29963c71b9e 
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#include <linux/init.h>
12#include <linux/pfn.h>
13#include <linux/bootmem.h>
14#include <linux/module.h>
15
16#include <asm/bug.h>
17#include <asm/io.h>
18#include <asm/processor.h>
19
20#include "internal.h"
21
22/*
23 * Access to this subsystem has to be serialized externally. (this is
24 * true for the boot process anyway)
25 */
26unsigned long max_low_pfn;
27unsigned long min_low_pfn;
28unsigned long max_pfn;
29
30static LIST_HEAD(bdata_list);
31#ifdef CONFIG_CRASH_DUMP
32/*
33 * If we have booted due to a crash, max_pfn will be a very low value. We need
34 * to know the amount of memory that the previous kernel used.
35 */
36unsigned long saved_max_pfn;
37#endif
38
39/* return the number of _pages_ that will be allocated for the boot bitmap */
40unsigned long __init bootmem_bootmap_pages(unsigned long pages)
41{
42	unsigned long mapsize;
43
44	mapsize = (pages+7)/8;
45	mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;
46	mapsize >>= PAGE_SHIFT;
47
48	return mapsize;
49}
50
51/*
52 * link bdata in order
53 */
54static void __init link_bootmem(bootmem_data_t *bdata)
55{
56	bootmem_data_t *ent;
57
58	if (list_empty(&bdata_list)) {
59		list_add(&bdata->list, &bdata_list);
60		return;
61	}
62	/* insert in order */
63	list_for_each_entry(ent, &bdata_list, list) {
64		if (bdata->node_boot_start < ent->node_boot_start) {
65			list_add_tail(&bdata->list, &ent->list);
66			return;
67		}
68	}
69	list_add_tail(&bdata->list, &bdata_list);
70}
71
72/*
73 * Given an initialised bdata, it returns the size of the boot bitmap
74 */
75static unsigned long __init get_mapsize(bootmem_data_t *bdata)
76{
77	unsigned long mapsize;
78	unsigned long start = PFN_DOWN(bdata->node_boot_start);
79	unsigned long end = bdata->node_low_pfn;
80
81	mapsize = ((end - start) + 7) / 8;
82	return ALIGN(mapsize, sizeof(long));
83}
84
85/*
86 * Called once to set up the allocator itself.
87 */
88static unsigned long __init init_bootmem_core(pg_data_t *pgdat,
89	unsigned long mapstart, unsigned long start, unsigned long end)
90{
91	bootmem_data_t *bdata = pgdat->bdata;
92	unsigned long mapsize;
93
94	bdata->node_bootmem_map = phys_to_virt(PFN_PHYS(mapstart));
95	bdata->node_boot_start = PFN_PHYS(start);
96	bdata->node_low_pfn = end;
97	link_bootmem(bdata);
98
99	/*
100	 * Initially all pages are reserved - setup_arch() has to
101	 * register free RAM areas explicitly.
102	 */
103	mapsize = get_mapsize(bdata);
104	memset(bdata->node_bootmem_map, 0xff, mapsize);
105
106	return mapsize;
107}
108
109/*
110 * Marks a particular physical memory range as unallocatable. Usable RAM
111 * might be used for boot-time allocations - or it might get added
112 * to the free page pool later on.
113 */
114static int __init reserve_bootmem_core(bootmem_data_t *bdata,
115			unsigned long addr, unsigned long size, int flags)
116{
117	unsigned long sidx, eidx;
118	unsigned long i;
119	int ret;
120
121	/*
122	 * round up, partially reserved pages are considered
123	 * fully reserved.
124	 */
125	BUG_ON(!size);
126	BUG_ON(PFN_DOWN(addr) >= bdata->node_low_pfn);
127	BUG_ON(PFN_UP(addr + size) > bdata->node_low_pfn);
128	BUG_ON(addr < bdata->node_boot_start);
129
130	sidx = PFN_DOWN(addr - bdata->node_boot_start);
131	eidx = PFN_UP(addr + size - bdata->node_boot_start);
132
133	for (i = sidx; i < eidx; i++)
134		if (test_and_set_bit(i, bdata->node_bootmem_map)) {
135#ifdef CONFIG_DEBUG_BOOTMEM
136			printk("hm, page %08lx reserved twice.\n", i*PAGE_SIZE);
137#endif
138			if (flags & BOOTMEM_EXCLUSIVE) {
139				ret = -EBUSY;
140				goto err;
141			}
142		}
143
144	return 0;
145
146err:
147	/* unreserve memory we accidentally reserved */
148	for (i--; i >= sidx; i--)
149		clear_bit(i, bdata->node_bootmem_map);
150
151	return ret;
152}
153
154static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
155				     unsigned long size)
156{
157	unsigned long sidx, eidx;
158	unsigned long i;
159
160	BUG_ON(!size);
161
162	/* out range */
163	if (addr + size < bdata->node_boot_start ||
164		PFN_DOWN(addr) > bdata->node_low_pfn)
165		return;
166	/*
167	 * round down end of usable mem, partially free pages are
168	 * considered reserved.
169	 */
170
171	if (addr >= bdata->node_boot_start && addr < bdata->last_success)
172		bdata->last_success = addr;
173
174	/*
175	 * Round up to index to the range.
176	 */
177	if (PFN_UP(addr) > PFN_DOWN(bdata->node_boot_start))
178		sidx = PFN_UP(addr) - PFN_DOWN(bdata->node_boot_start);
179	else
180		sidx = 0;
181
182	eidx = PFN_DOWN(addr + size - bdata->node_boot_start);
183	if (eidx > bdata->node_low_pfn - PFN_DOWN(bdata->node_boot_start))
184		eidx = bdata->node_low_pfn - PFN_DOWN(bdata->node_boot_start);
185
186	for (i = sidx; i < eidx; i++) {
187		if (unlikely(!test_and_clear_bit(i, bdata->node_bootmem_map)))
188			BUG();
189	}
190}
191
192/*
193 * We 'merge' subsequent allocations to save space. We might 'lose'
194 * some fraction of a page if allocations cannot be satisfied due to
195 * size constraints on boxes where there is physical RAM space
196 * fragmentation - in these cases (mostly large memory boxes) this
197 * is not a problem.
198 *
199 * On low memory boxes we get it right in 100% of the cases.
200 *
201 * alignment has to be a power of 2 value.
202 *
203 * NOTE:  This function is _not_ reentrant.
204 */
205void * __init
206__alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
207	      unsigned long align, unsigned long goal, unsigned long limit)
208{
209	unsigned long offset, remaining_size, areasize, preferred;
210	unsigned long i, start = 0, incr, eidx, end_pfn;
211	void *ret;
212
213	if (!size) {
214		printk("__alloc_bootmem_core(): zero-sized request\n");
215		BUG();
216	}
217	BUG_ON(align & (align-1));
218
219	if (limit && bdata->node_boot_start >= limit)
220		return NULL;
221
222	/* on nodes without memory - bootmem_map is NULL */
223	if (!bdata->node_bootmem_map)
224		return NULL;
225
226	end_pfn = bdata->node_low_pfn;
227	limit = PFN_DOWN(limit);
228	if (limit && end_pfn > limit)
229		end_pfn = limit;
230
231	eidx = end_pfn - PFN_DOWN(bdata->node_boot_start);
232	offset = 0;
233	if (align && (bdata->node_boot_start & (align - 1UL)) != 0)
234		offset = align - (bdata->node_boot_start & (align - 1UL));
235	offset = PFN_DOWN(offset);
236
237	/*
238	 * We try to allocate bootmem pages above 'goal'
239	 * first, then we try to allocate lower pages.
240	 */
241	if (goal && goal >= bdata->node_boot_start && PFN_DOWN(goal) < end_pfn) {
242		preferred = goal - bdata->node_boot_start;
243
244		if (bdata->last_success >= preferred)
245			if (!limit || (limit && limit > bdata->last_success))
246				preferred = bdata->last_success;
247	} else
248		preferred = 0;
249
250	preferred = PFN_DOWN(ALIGN(preferred, align)) + offset;
251	areasize = (size + PAGE_SIZE-1) / PAGE_SIZE;
252	incr = align >> PAGE_SHIFT ? : 1;
253
254restart_scan:
255	for (i = preferred; i < eidx; i += incr) {
256		unsigned long j;
257		i = find_next_zero_bit(bdata->node_bootmem_map, eidx, i);
258		i = ALIGN(i, incr);
259		if (i >= eidx)
260			break;
261		if (test_bit(i, bdata->node_bootmem_map))
262			continue;
263		for (j = i + 1; j < i + areasize; ++j) {
264			if (j >= eidx)
265				goto fail_block;
266			if (test_bit(j, bdata->node_bootmem_map))
267				goto fail_block;
268		}
269		start = i;
270		goto found;
271	fail_block:
272		i = ALIGN(j, incr);
273	}
274
275	if (preferred > offset) {
276		preferred = offset;
277		goto restart_scan;
278	}
279	return NULL;
280
281found:
282	bdata->last_success = PFN_PHYS(start);
283	BUG_ON(start >= eidx);
284
285	/*
286	 * Is the next page of the previous allocation-end the start
287	 * of this allocation's buffer? If yes then we can 'merge'
288	 * the previous partial page with this allocation.
289	 */
290	if (align < PAGE_SIZE &&
291	    bdata->last_offset && bdata->last_pos+1 == start) {
292		offset = ALIGN(bdata->last_offset, align);
293		BUG_ON(offset > PAGE_SIZE);
294		remaining_size = PAGE_SIZE - offset;
295		if (size < remaining_size) {
296			areasize = 0;
297			/* last_pos unchanged */
298			bdata->last_offset = offset + size;
299			ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
300					   offset +
301					   bdata->node_boot_start);
302		} else {
303			remaining_size = size - remaining_size;
304			areasize = (remaining_size + PAGE_SIZE-1) / PAGE_SIZE;
305			ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
306					   offset +
307					   bdata->node_boot_start);
308			bdata->last_pos = start + areasize - 1;
309			bdata->last_offset = remaining_size;
310		}
311		bdata->last_offset &= ~PAGE_MASK;
312	} else {
313		bdata->last_pos = start + areasize - 1;
314		bdata->last_offset = size & ~PAGE_MASK;
315		ret = phys_to_virt(start * PAGE_SIZE + bdata->node_boot_start);
316	}
317
318	/*
319	 * Reserve the area now:
320	 */
321	for (i = start; i < start + areasize; i++)
322		if (unlikely(test_and_set_bit(i, bdata->node_bootmem_map)))
323			BUG();
324	memset(ret, 0, size);
325	return ret;
326}
327
328static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
329{
330	struct page *page;
331	unsigned long pfn;
332	bootmem_data_t *bdata = pgdat->bdata;
333	unsigned long i, count, total = 0;
334	unsigned long idx;
335	unsigned long *map;
336	int gofast = 0;
337
338	BUG_ON(!bdata->node_bootmem_map);
339
340	count = 0;
341	/* first extant page of the node */
342	pfn = PFN_DOWN(bdata->node_boot_start);
343	idx = bdata->node_low_pfn - pfn;
344	map = bdata->node_bootmem_map;
345	/* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */
346	if (bdata->node_boot_start == 0 ||
347	    ffs(bdata->node_boot_start) - PAGE_SHIFT > ffs(BITS_PER_LONG))
348		gofast = 1;
349	for (i = 0; i < idx; ) {
350		unsigned long v = ~map[i / BITS_PER_LONG];
351
352		if (gofast && v == ~0UL) {
353			int order;
354
355			page = pfn_to_page(pfn);
356			count += BITS_PER_LONG;
357			order = ffs(BITS_PER_LONG) - 1;
358			__free_pages_bootmem(page, order);
359			i += BITS_PER_LONG;
360			page += BITS_PER_LONG;
361		} else if (v) {
362			unsigned long m;
363
364			page = pfn_to_page(pfn);
365			for (m = 1; m && i < idx; m<<=1, page++, i++) {
366				if (v & m) {
367					count++;
368					__free_pages_bootmem(page, 0);
369				}
370			}
371		} else {
372			i += BITS_PER_LONG;
373		}
374		pfn += BITS_PER_LONG;
375	}
376	total += count;
377
378	/*
379	 * Now free the allocator bitmap itself, it's not
380	 * needed anymore:
381	 */
382	page = virt_to_page(bdata->node_bootmem_map);
383	count = 0;
384	idx = (get_mapsize(bdata) + PAGE_SIZE-1) >> PAGE_SHIFT;
385	for (i = 0; i < idx; i++, page++) {
386		__free_pages_bootmem(page, 0);
387		count++;
388	}
389	total += count;
390	bdata->node_bootmem_map = NULL;
391
392	return total;
393}
394
395unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn,
396				unsigned long startpfn, unsigned long endpfn)
397{
398	return init_bootmem_core(pgdat, freepfn, startpfn, endpfn);
399}
400
401void __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
402				 unsigned long size, int flags)
403{
404	reserve_bootmem_core(pgdat->bdata, physaddr, size, flags);
405}
406
407void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
408			      unsigned long size)
409{
410	free_bootmem_core(pgdat->bdata, physaddr, size);
411}
412
413unsigned long __init free_all_bootmem_node(pg_data_t *pgdat)
414{
415	return free_all_bootmem_core(pgdat);
416}
417
418unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
419{
420	max_low_pfn = pages;
421	min_low_pfn = start;
422	return init_bootmem_core(NODE_DATA(0), start, 0, pages);
423}
424
425#ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
426int __init reserve_bootmem(unsigned long addr, unsigned long size,
427			    int flags)
428{
429	return reserve_bootmem_core(NODE_DATA(0)->bdata, addr, size, flags);
430}
431#endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */
432
433void __init free_bootmem(unsigned long addr, unsigned long size)
434{
435	bootmem_data_t *bdata;
436	list_for_each_entry(bdata, &bdata_list, list)
437		free_bootmem_core(bdata, addr, size);
438}
439
440unsigned long __init free_all_bootmem(void)
441{
442	return free_all_bootmem_core(NODE_DATA(0));
443}
444
445void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
446				      unsigned long goal)
447{
448	bootmem_data_t *bdata;
449	void *ptr;
450
451	list_for_each_entry(bdata, &bdata_list, list) {
452		ptr = __alloc_bootmem_core(bdata, size, align, goal, 0);
453		if (ptr)
454			return ptr;
455	}
456	return NULL;
457}
458
459void * __init __alloc_bootmem(unsigned long size, unsigned long align,
460			      unsigned long goal)
461{
462	void *mem = __alloc_bootmem_nopanic(size,align,goal);
463
464	if (mem)
465		return mem;
466	/*
467	 * Whoops, we cannot satisfy the allocation request.
468	 */
469	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
470	panic("Out of memory");
471	return NULL;
472}
473
474
475void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
476				   unsigned long align, unsigned long goal)
477{
478	void *ptr;
479
480	ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal, 0);
481	if (ptr)
482		return ptr;
483
484	return __alloc_bootmem(size, align, goal);
485}
486
487#ifndef ARCH_LOW_ADDRESS_LIMIT
488#define ARCH_LOW_ADDRESS_LIMIT	0xffffffffUL
489#endif
490
491void * __init __alloc_bootmem_low(unsigned long size, unsigned long align,
492				  unsigned long goal)
493{
494	bootmem_data_t *bdata;
495	void *ptr;
496
497	list_for_each_entry(bdata, &bdata_list, list) {
498		ptr = __alloc_bootmem_core(bdata, size, align, goal,
499						ARCH_LOW_ADDRESS_LIMIT);
500		if (ptr)
501			return ptr;
502	}
503
504	/*
505	 * Whoops, we cannot satisfy the allocation request.
506	 */
507	printk(KERN_ALERT "low bootmem alloc of %lu bytes failed!\n", size);
508	panic("Out of low memory");
509	return NULL;
510}
511
512void * __init __alloc_bootmem_low_node(pg_data_t *pgdat, unsigned long size,
513				       unsigned long align, unsigned long goal)
514{
515	return __alloc_bootmem_core(pgdat->bdata, size, align, goal,
516				    ARCH_LOW_ADDRESS_LIMIT);
517}
518