Root/mm/sparse-vmemmap.c

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 __alloc_bootmem_node_high(NODE_DATA(node), size, align, goal);
44}
45
46static void *vmemmap_buf;
47static void *vmemmap_buf_end;
48
49void * __meminit vmemmap_alloc_block(unsigned long size, int node)
50{
51    /* If the main allocator is up use that, fallback to bootmem. */
52    if (slab_is_available()) {
53        struct page *page;
54
55        if (node_state(node, N_HIGH_MEMORY))
56            page = alloc_pages_node(node,
57                GFP_KERNEL | __GFP_ZERO, get_order(size));
58        else
59            page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
60                get_order(size));
61        if (page)
62            return page_address(page);
63        return NULL;
64    } else
65        return __earlyonly_bootmem_alloc(node, size, size,
66                __pa(MAX_DMA_ADDRESS));
67}
68
69/* need to make sure size is all the same during early stage */
70void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
71{
72    void *ptr;
73
74    if (!vmemmap_buf)
75        return vmemmap_alloc_block(size, node);
76
77    /* take the from buf */
78    ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
79    if (ptr + size > vmemmap_buf_end)
80        return vmemmap_alloc_block(size, node);
81
82    vmemmap_buf = ptr + size;
83
84    return ptr;
85}
86
87void __meminit vmemmap_verify(pte_t *pte, int node,
88                unsigned long start, unsigned long end)
89{
90    unsigned long pfn = pte_pfn(*pte);
91    int actual_node = early_pfn_to_nid(pfn);
92
93    if (node_distance(actual_node, node) > LOCAL_DISTANCE)
94        printk(KERN_WARNING "[%lx-%lx] potential offnode "
95            "page_structs\n", start, end - 1);
96}
97
98pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
99{
100    pte_t *pte = pte_offset_kernel(pmd, addr);
101    if (pte_none(*pte)) {
102        pte_t entry;
103        void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
104        if (!p)
105            return NULL;
106        entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
107        set_pte_at(&init_mm, addr, pte, entry);
108    }
109    return pte;
110}
111
112pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
113{
114    pmd_t *pmd = pmd_offset(pud, addr);
115    if (pmd_none(*pmd)) {
116        void *p = vmemmap_alloc_block(PAGE_SIZE, node);
117        if (!p)
118            return NULL;
119        pmd_populate_kernel(&init_mm, pmd, p);
120    }
121    return pmd;
122}
123
124pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
125{
126    pud_t *pud = pud_offset(pgd, addr);
127    if (pud_none(*pud)) {
128        void *p = vmemmap_alloc_block(PAGE_SIZE, node);
129        if (!p)
130            return NULL;
131        pud_populate(&init_mm, pud, p);
132    }
133    return pud;
134}
135
136pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
137{
138    pgd_t *pgd = pgd_offset_k(addr);
139    if (pgd_none(*pgd)) {
140        void *p = vmemmap_alloc_block(PAGE_SIZE, node);
141        if (!p)
142            return NULL;
143        pgd_populate(&init_mm, pgd, p);
144    }
145    return pgd;
146}
147
148int __meminit vmemmap_populate_basepages(struct page *start_page,
149                        unsigned long size, int node)
150{
151    unsigned long addr = (unsigned long)start_page;
152    unsigned long end = (unsigned long)(start_page + size);
153    pgd_t *pgd;
154    pud_t *pud;
155    pmd_t *pmd;
156    pte_t *pte;
157
158    for (; addr < end; addr += PAGE_SIZE) {
159        pgd = vmemmap_pgd_populate(addr, node);
160        if (!pgd)
161            return -ENOMEM;
162        pud = vmemmap_pud_populate(pgd, addr, node);
163        if (!pud)
164            return -ENOMEM;
165        pmd = vmemmap_pmd_populate(pud, addr, node);
166        if (!pmd)
167            return -ENOMEM;
168        pte = vmemmap_pte_populate(pmd, addr, node);
169        if (!pte)
170            return -ENOMEM;
171        vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
172    }
173
174    return 0;
175}
176
177struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
178{
179    struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
180    int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
181    if (error)
182        return NULL;
183
184    return map;
185}
186
187void __init sparse_mem_maps_populate_node(struct page **map_map,
188                      unsigned long pnum_begin,
189                      unsigned long pnum_end,
190                      unsigned long map_count, int nodeid)
191{
192    unsigned long pnum;
193    unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
194    void *vmemmap_buf_start;
195
196    size = ALIGN(size, PMD_SIZE);
197    vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
198             PMD_SIZE, __pa(MAX_DMA_ADDRESS));
199
200    if (vmemmap_buf_start) {
201        vmemmap_buf = vmemmap_buf_start;
202        vmemmap_buf_end = vmemmap_buf_start + size * map_count;
203    }
204
205    for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
206        struct mem_section *ms;
207
208        if (!present_section_nr(pnum))
209            continue;
210
211        map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
212        if (map_map[pnum])
213            continue;
214        ms = __nr_to_section(pnum);
215        printk(KERN_ERR "%s: sparsemem memory map backing failed "
216            "some memory will not be available.\n", __func__);
217        ms->section_mem_map = 0;
218    }
219
220    if (vmemmap_buf_start) {
221        /* need to free left buf */
222        free_bootmem(__pa(vmemmap_buf), vmemmap_buf_end - vmemmap_buf);
223        vmemmap_buf = NULL;
224        vmemmap_buf_end = NULL;
225    }
226}
227

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