bootmem.c revision 9a2dc04cf070ee98e014a172695782ff42015fc4 
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 areasize, preferred;
210	unsigned long i, start = 0, incr, eidx, end_pfn;
211	void *ret;
212	unsigned long node_boot_start;
213	void *node_bootmem_map;
214
215	if (!size) {
216		printk("__alloc_bootmem_core(): zero-sized request\n");
217		BUG();
218	}
219	BUG_ON(align & (align-1));
220
221	/* on nodes without memory - bootmem_map is NULL */
222	if (!bdata->node_bootmem_map)
223		return NULL;
224
225	/* bdata->node_boot_start is supposed to be (12+6)bits alignment on x86_64 ? */
226	node_boot_start = bdata->node_boot_start;
227	node_bootmem_map = bdata->node_bootmem_map;
228	if (align) {
229		node_boot_start = ALIGN(bdata->node_boot_start, align);
230		if (node_boot_start > bdata->node_boot_start)
231			node_bootmem_map = (unsigned long *)bdata->node_bootmem_map +
232			    PFN_DOWN(node_boot_start - bdata->node_boot_start)/BITS_PER_LONG;
233	}
234
235	if (limit && node_boot_start >= limit)
236		return NULL;
237
238	end_pfn = bdata->node_low_pfn;
239	limit = PFN_DOWN(limit);
240	if (limit && end_pfn > limit)
241		end_pfn = limit;
242
243	eidx = end_pfn - PFN_DOWN(node_boot_start);
244
245	/*
246	 * We try to allocate bootmem pages above 'goal'
247	 * first, then we try to allocate lower pages.
248	 */
249	preferred = 0;
250	if (goal && PFN_DOWN(goal) < end_pfn) {
251		if (goal > node_boot_start)
252			preferred = goal - node_boot_start;
253
254		if (bdata->last_success > node_boot_start &&
255			bdata->last_success - node_boot_start >= preferred)
256			if (!limit || (limit && limit > bdata->last_success))
257				preferred = bdata->last_success - node_boot_start;
258	}
259
260	preferred = PFN_DOWN(ALIGN(preferred, align));
261	areasize = (size + PAGE_SIZE-1) / PAGE_SIZE;
262	incr = align >> PAGE_SHIFT ? : 1;
263
264restart_scan:
265	for (i = preferred; i < eidx;) {
266		unsigned long j;
267
268		i = find_next_zero_bit(node_bootmem_map, eidx, i);
269		i = ALIGN(i, incr);
270		if (i >= eidx)
271			break;
272		if (test_bit(i, node_bootmem_map)) {
273			i += incr;
274			continue;
275		}
276		for (j = i + 1; j < i + areasize; ++j) {
277			if (j >= eidx)
278				goto fail_block;
279			if (test_bit(j, node_bootmem_map))
280				goto fail_block;
281		}
282		start = i;
283		goto found;
284	fail_block:
285		i = ALIGN(j, incr);
286		if (i == j)
287			i += incr;
288	}
289
290	if (preferred > 0) {
291		preferred = 0;
292		goto restart_scan;
293	}
294	return NULL;
295
296found:
297	bdata->last_success = PFN_PHYS(start) + node_boot_start;
298	BUG_ON(start >= eidx);
299
300	/*
301	 * Is the next page of the previous allocation-end the start
302	 * of this allocation's buffer? If yes then we can 'merge'
303	 * the previous partial page with this allocation.
304	 */
305	if (align < PAGE_SIZE &&
306	    bdata->last_offset && bdata->last_pos+1 == start) {
307		unsigned long offset, remaining_size;
308		offset = ALIGN(bdata->last_offset, align);
309		BUG_ON(offset > PAGE_SIZE);
310		remaining_size = PAGE_SIZE - offset;
311		if (size < remaining_size) {
312			areasize = 0;
313			/* last_pos unchanged */
314			bdata->last_offset = offset + size;
315			ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
316					   offset + node_boot_start);
317		} else {
318			remaining_size = size - remaining_size;
319			areasize = (remaining_size + PAGE_SIZE-1) / PAGE_SIZE;
320			ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
321					   offset + node_boot_start);
322			bdata->last_pos = start + areasize - 1;
323			bdata->last_offset = remaining_size;
324		}
325		bdata->last_offset &= ~PAGE_MASK;
326	} else {
327		bdata->last_pos = start + areasize - 1;
328		bdata->last_offset = size & ~PAGE_MASK;
329		ret = phys_to_virt(start * PAGE_SIZE + node_boot_start);
330	}
331
332	/*
333	 * Reserve the area now:
334	 */
335	for (i = start; i < start + areasize; i++)
336		if (unlikely(test_and_set_bit(i, node_bootmem_map)))
337			BUG();
338	memset(ret, 0, size);
339	return ret;
340}
341
342static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
343{
344	struct page *page;
345	unsigned long pfn;
346	bootmem_data_t *bdata = pgdat->bdata;
347	unsigned long i, count, total = 0;
348	unsigned long idx;
349	unsigned long *map;
350	int gofast = 0;
351
352	BUG_ON(!bdata->node_bootmem_map);
353
354	count = 0;
355	/* first extant page of the node */
356	pfn = PFN_DOWN(bdata->node_boot_start);
357	idx = bdata->node_low_pfn - pfn;
358	map = bdata->node_bootmem_map;
359	/* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */
360	if (bdata->node_boot_start == 0 ||
361	    ffs(bdata->node_boot_start) - PAGE_SHIFT > ffs(BITS_PER_LONG))
362		gofast = 1;
363	for (i = 0; i < idx; ) {
364		unsigned long v = ~map[i / BITS_PER_LONG];
365
366		if (gofast && v == ~0UL) {
367			int order;
368
369			page = pfn_to_page(pfn);
370			count += BITS_PER_LONG;
371			order = ffs(BITS_PER_LONG) - 1;
372			__free_pages_bootmem(page, order);
373			i += BITS_PER_LONG;
374			page += BITS_PER_LONG;
375		} else if (v) {
376			unsigned long m;
377
378			page = pfn_to_page(pfn);
379			for (m = 1; m && i < idx; m<<=1, page++, i++) {
380				if (v & m) {
381					count++;
382					__free_pages_bootmem(page, 0);
383				}
384			}
385		} else {
386			i += BITS_PER_LONG;
387		}
388		pfn += BITS_PER_LONG;
389	}
390	total += count;
391
392	/*
393	 * Now free the allocator bitmap itself, it's not
394	 * needed anymore:
395	 */
396	page = virt_to_page(bdata->node_bootmem_map);
397	count = 0;
398	idx = (get_mapsize(bdata) + PAGE_SIZE-1) >> PAGE_SHIFT;
399	for (i = 0; i < idx; i++, page++) {
400		__free_pages_bootmem(page, 0);
401		count++;
402	}
403	total += count;
404	bdata->node_bootmem_map = NULL;
405
406	return total;
407}
408
409unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn,
410				unsigned long startpfn, unsigned long endpfn)
411{
412	return init_bootmem_core(pgdat, freepfn, startpfn, endpfn);
413}
414
415void __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
416				 unsigned long size, int flags)
417{
418	reserve_bootmem_core(pgdat->bdata, physaddr, size, flags);
419}
420
421void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
422			      unsigned long size)
423{
424	free_bootmem_core(pgdat->bdata, physaddr, size);
425}
426
427unsigned long __init free_all_bootmem_node(pg_data_t *pgdat)
428{
429	return free_all_bootmem_core(pgdat);
430}
431
432unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
433{
434	max_low_pfn = pages;
435	min_low_pfn = start;
436	return init_bootmem_core(NODE_DATA(0), start, 0, pages);
437}
438
439#ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
440int __init reserve_bootmem(unsigned long addr, unsigned long size,
441			    int flags)
442{
443	return reserve_bootmem_core(NODE_DATA(0)->bdata, addr, size, flags);
444}
445#endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */
446
447void __init free_bootmem(unsigned long addr, unsigned long size)
448{
449	bootmem_data_t *bdata;
450	list_for_each_entry(bdata, &bdata_list, list)
451		free_bootmem_core(bdata, addr, size);
452}
453
454unsigned long __init free_all_bootmem(void)
455{
456	return free_all_bootmem_core(NODE_DATA(0));
457}
458
459void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
460				      unsigned long goal)
461{
462	bootmem_data_t *bdata;
463	void *ptr;
464
465	list_for_each_entry(bdata, &bdata_list, list) {
466		ptr = __alloc_bootmem_core(bdata, size, align, goal, 0);
467		if (ptr)
468			return ptr;
469	}
470	return NULL;
471}
472
473void * __init __alloc_bootmem(unsigned long size, unsigned long align,
474			      unsigned long goal)
475{
476	void *mem = __alloc_bootmem_nopanic(size,align,goal);
477
478	if (mem)
479		return mem;
480	/*
481	 * Whoops, we cannot satisfy the allocation request.
482	 */
483	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
484	panic("Out of memory");
485	return NULL;
486}
487
488
489void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
490				   unsigned long align, unsigned long goal)
491{
492	void *ptr;
493
494	ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal, 0);
495	if (ptr)
496		return ptr;
497
498	return __alloc_bootmem(size, align, goal);
499}
500
501#ifndef ARCH_LOW_ADDRESS_LIMIT
502#define ARCH_LOW_ADDRESS_LIMIT	0xffffffffUL
503#endif
504
505void * __init __alloc_bootmem_low(unsigned long size, unsigned long align,
506				  unsigned long goal)
507{
508	bootmem_data_t *bdata;
509	void *ptr;
510
511	list_for_each_entry(bdata, &bdata_list, list) {
512		ptr = __alloc_bootmem_core(bdata, size, align, goal,
513						ARCH_LOW_ADDRESS_LIMIT);
514		if (ptr)
515			return ptr;
516	}
517
518	/*
519	 * Whoops, we cannot satisfy the allocation request.
520	 */
521	printk(KERN_ALERT "low bootmem alloc of %lu bytes failed!\n", size);
522	panic("Out of low memory");
523	return NULL;
524}
525
526void * __init __alloc_bootmem_low_node(pg_data_t *pgdat, unsigned long size,
527				       unsigned long align, unsigned long goal)
528{
529	return __alloc_bootmem_core(pgdat->bdata, size, align, goal,
530				    ARCH_LOW_ADDRESS_LIMIT);
531}
532