1/*
2 * Virtual Memory Map support
3 *
4 * (C) 2007 sgi. Christoph Lameter.
5 *
6 * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
7 * virt_to_page, page_address() to be implemented as a base offset
8 * calculation without memory access.
9 *
10 * However, virtual mappings need a page table and TLBs. Many Linux
11 * architectures already map their physical space using 1-1 mappings
12 * via TLBs. For those arches the virtual memory map is essentially
13 * for free if we use the same page size as the 1-1 mappings. In that
14 * case the overhead consists of a few additional pages that are
15 * allocated to create a view of memory for vmemmap.
16 *
17 * The architecture is expected to provide a vmemmap_populate() function
18 * to instantiate the mapping.
19 */
20#include <linux/mm.h>
21#include <linux/mmzone.h>
22#include <linux/bootmem.h>
23#include <linux/highmem.h>
24#include <linux/slab.h>
25#include <linux/spinlock.h>
26#include <linux/vmalloc.h>
27#include <linux/sched.h>
28#include <asm/dma.h>
29#include <asm/pgalloc.h>
30#include <asm/pgtable.h>
31
32/*
33 * Allocate a block of memory to be used to back the virtual memory map
34 * or to back the page tables that are used to create the mapping.
35 * Uses the main allocators if they are available, else bootmem.
36 */
37
38static void * __init_refok __earlyonly_bootmem_alloc(int node,
39				unsigned long size,
40				unsigned long align,
41				unsigned long goal)
42{
43	return memblock_virt_alloc_try_nid(size, align, goal,
44					    BOOTMEM_ALLOC_ACCESSIBLE, node);
45}
46
47static void *vmemmap_buf;
48static void *vmemmap_buf_end;
49
50void * __meminit vmemmap_alloc_block(unsigned long size, int node)
51{
52	/* If the main allocator is up use that, fallback to bootmem. */
53	if (slab_is_available()) {
54		struct page *page;
55
56		if (node_state(node, N_HIGH_MEMORY))
57			page = alloc_pages_node(
58				node, GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
59				get_order(size));
60		else
61			page = alloc_pages(
62				GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
63				get_order(size));
64		if (page)
65			return page_address(page);
66		return NULL;
67	} else
68		return __earlyonly_bootmem_alloc(node, size, size,
69				__pa(MAX_DMA_ADDRESS));
70}
71
72/* need to make sure size is all the same during early stage */
73void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
74{
75	void *ptr;
76
77	if (!vmemmap_buf)
78		return vmemmap_alloc_block(size, node);
79
80	/* take the from buf */
81	ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
82	if (ptr + size > vmemmap_buf_end)
83		return vmemmap_alloc_block(size, node);
84
85	vmemmap_buf = ptr + size;
86
87	return ptr;
88}
89
90void __meminit vmemmap_verify(pte_t *pte, int node,
91				unsigned long start, unsigned long end)
92{
93	unsigned long pfn = pte_pfn(*pte);
94	int actual_node = early_pfn_to_nid(pfn);
95
96	if (node_distance(actual_node, node) > LOCAL_DISTANCE)
97		printk(KERN_WARNING "[%lx-%lx] potential offnode "
98			"page_structs\n", start, end - 1);
99}
100
101pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
102{
103	pte_t *pte = pte_offset_kernel(pmd, addr);
104	if (pte_none(*pte)) {
105		pte_t entry;
106		void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
107		if (!p)
108			return NULL;
109		entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
110		set_pte_at(&init_mm, addr, pte, entry);
111	}
112	return pte;
113}
114
115pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
116{
117	pmd_t *pmd = pmd_offset(pud, addr);
118	if (pmd_none(*pmd)) {
119		void *p = vmemmap_alloc_block(PAGE_SIZE, node);
120		if (!p)
121			return NULL;
122		pmd_populate_kernel(&init_mm, pmd, p);
123	}
124	return pmd;
125}
126
127pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
128{
129	pud_t *pud = pud_offset(pgd, addr);
130	if (pud_none(*pud)) {
131		void *p = vmemmap_alloc_block(PAGE_SIZE, node);
132		if (!p)
133			return NULL;
134		pud_populate(&init_mm, pud, p);
135	}
136	return pud;
137}
138
139pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
140{
141	pgd_t *pgd = pgd_offset_k(addr);
142	if (pgd_none(*pgd)) {
143		void *p = vmemmap_alloc_block(PAGE_SIZE, node);
144		if (!p)
145			return NULL;
146		pgd_populate(&init_mm, pgd, p);
147	}
148	return pgd;
149}
150
151int __meminit vmemmap_populate_basepages(unsigned long start,
152					 unsigned long end, int node)
153{
154	unsigned long addr = start;
155	pgd_t *pgd;
156	pud_t *pud;
157	pmd_t *pmd;
158	pte_t *pte;
159
160	for (; addr < end; addr += PAGE_SIZE) {
161		pgd = vmemmap_pgd_populate(addr, node);
162		if (!pgd)
163			return -ENOMEM;
164		pud = vmemmap_pud_populate(pgd, addr, node);
165		if (!pud)
166			return -ENOMEM;
167		pmd = vmemmap_pmd_populate(pud, addr, node);
168		if (!pmd)
169			return -ENOMEM;
170		pte = vmemmap_pte_populate(pmd, addr, node);
171		if (!pte)
172			return -ENOMEM;
173		vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
174	}
175
176	return 0;
177}
178
179struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
180{
181	unsigned long start;
182	unsigned long end;
183	struct page *map;
184
185	map = pfn_to_page(pnum * PAGES_PER_SECTION);
186	start = (unsigned long)map;
187	end = (unsigned long)(map + PAGES_PER_SECTION);
188
189	if (vmemmap_populate(start, end, nid))
190		return NULL;
191
192	return map;
193}
194
195void __init sparse_mem_maps_populate_node(struct page **map_map,
196					  unsigned long pnum_begin,
197					  unsigned long pnum_end,
198					  unsigned long map_count, int nodeid)
199{
200	unsigned long pnum;
201	unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
202	void *vmemmap_buf_start;
203
204	size = ALIGN(size, PMD_SIZE);
205	vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
206			 PMD_SIZE, __pa(MAX_DMA_ADDRESS));
207
208	if (vmemmap_buf_start) {
209		vmemmap_buf = vmemmap_buf_start;
210		vmemmap_buf_end = vmemmap_buf_start + size * map_count;
211	}
212
213	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
214		struct mem_section *ms;
215
216		if (!present_section_nr(pnum))
217			continue;
218
219		map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
220		if (map_map[pnum])
221			continue;
222		ms = __nr_to_section(pnum);
223		printk(KERN_ERR "%s: sparsemem memory map backing failed "
224			"some memory will not be available.\n", __func__);
225		ms->section_mem_map = 0;
226	}
227
228	if (vmemmap_buf_start) {
229		/* need to free left buf */
230		memblock_free_early(__pa(vmemmap_buf),
231				    vmemmap_buf_end - vmemmap_buf);
232		vmemmap_buf = NULL;
233		vmemmap_buf_end = NULL;
234	}
235}
236