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/module.h>
25#include <linux/slab.h>
26#include <linux/spinlock.h>
27#include <linux/vmalloc.h>
28#include <linux/sched.h>
29#include <asm/dma.h>
30#include <asm/pgalloc.h>
31#include <asm/pgtable.h>
32
33/*
34 * Allocate a block of memory to be used to back the virtual memory map
35 * or to back the page tables that are used to create the mapping.
36 * Uses the main allocators if they are available, else bootmem.
37 */
38
39static void * __init_refok __earlyonly_bootmem_alloc(int node,
40                unsigned long size,
41                unsigned long align,
42                unsigned long goal)
43{
44    return __alloc_bootmem_node_high(NODE_DATA(node), size, align, goal);
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(node,
58                GFP_KERNEL | __GFP_ZERO, get_order(size));
59        else
60            page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
61                get_order(size));
62        if (page)
63            return page_address(page);
64        return NULL;
65    } else
66        return __earlyonly_bootmem_alloc(node, size, size,
67                __pa(MAX_DMA_ADDRESS));
68}
69
70/* need to make sure size is all the same during early stage */
71void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
72{
73    void *ptr;
74
75    if (!vmemmap_buf)
76        return vmemmap_alloc_block(size, node);
77
78    /* take the from buf */
79    ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
80    if (ptr + size > vmemmap_buf_end)
81        return vmemmap_alloc_block(size, node);
82
83    vmemmap_buf = ptr + size;
84
85    return ptr;
86}
87
88void __meminit vmemmap_verify(pte_t *pte, int node,
89                unsigned long start, unsigned long end)
90{
91    unsigned long pfn = pte_pfn(*pte);
92    int actual_node = early_pfn_to_nid(pfn);
93
94    if (node_distance(actual_node, node) > LOCAL_DISTANCE)
95        printk(KERN_WARNING "[%lx-%lx] potential offnode "
96            "page_structs\n", start, end - 1);
97}
98
99pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
100{
101    pte_t *pte = pte_offset_kernel(pmd, addr);
102    if (pte_none(*pte)) {
103        pte_t entry;
104        void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
105        if (!p)
106            return NULL;
107        entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
108        set_pte_at(&init_mm, addr, pte, entry);
109    }
110    return pte;
111}
112
113pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
114{
115    pmd_t *pmd = pmd_offset(pud, addr);
116    if (pmd_none(*pmd)) {
117        void *p = vmemmap_alloc_block(PAGE_SIZE, node);
118        if (!p)
119            return NULL;
120        pmd_populate_kernel(&init_mm, pmd, p);
121    }
122    return pmd;
123}
124
125pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
126{
127    pud_t *pud = pud_offset(pgd, addr);
128    if (pud_none(*pud)) {
129        void *p = vmemmap_alloc_block(PAGE_SIZE, node);
130        if (!p)
131            return NULL;
132        pud_populate(&init_mm, pud, p);
133    }
134    return pud;
135}
136
137pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
138{
139    pgd_t *pgd = pgd_offset_k(addr);
140    if (pgd_none(*pgd)) {
141        void *p = vmemmap_alloc_block(PAGE_SIZE, node);
142        if (!p)
143            return NULL;
144        pgd_populate(&init_mm, pgd, p);
145    }
146    return pgd;
147}
148
149int __meminit vmemmap_populate_basepages(struct page *start_page,
150                        unsigned long size, int node)
151{
152    unsigned long addr = (unsigned long)start_page;
153    unsigned long end = (unsigned long)(start_page + size);
154    pgd_t *pgd;
155    pud_t *pud;
156    pmd_t *pmd;
157    pte_t *pte;
158
159    for (; addr < end; addr += PAGE_SIZE) {
160        pgd = vmemmap_pgd_populate(addr, node);
161        if (!pgd)
162            return -ENOMEM;
163        pud = vmemmap_pud_populate(pgd, addr, node);
164        if (!pud)
165            return -ENOMEM;
166        pmd = vmemmap_pmd_populate(pud, addr, node);
167        if (!pmd)
168            return -ENOMEM;
169        pte = vmemmap_pte_populate(pmd, addr, node);
170        if (!pte)
171            return -ENOMEM;
172        vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
173    }
174
175    return 0;
176}
177
178struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
179{
180    struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
181    int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
182    if (error)
183        return NULL;
184
185    return map;
186}
187
188void __init sparse_mem_maps_populate_node(struct page **map_map,
189                      unsigned long pnum_begin,
190                      unsigned long pnum_end,
191                      unsigned long map_count, int nodeid)
192{
193    unsigned long pnum;
194    unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
195    void *vmemmap_buf_start;
196
197    size = ALIGN(size, PMD_SIZE);
198    vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
199             PMD_SIZE, __pa(MAX_DMA_ADDRESS));
200
201    if (vmemmap_buf_start) {
202        vmemmap_buf = vmemmap_buf_start;
203        vmemmap_buf_end = vmemmap_buf_start + size * map_count;
204    }
205
206    for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
207        struct mem_section *ms;
208
209        if (!present_section_nr(pnum))
210            continue;
211
212        map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
213        if (map_map[pnum])
214            continue;
215        ms = __nr_to_section(pnum);
216        printk(KERN_ERR "%s: sparsemem memory map backing failed "
217            "some memory will not be available.\n", __func__);
218        ms->section_mem_map = 0;
219    }
220
221    if (vmemmap_buf_start) {
222        /* need to free left buf */
223        free_bootmem(__pa(vmemmap_buf), vmemmap_buf_end - vmemmap_buf);
224        vmemmap_buf = NULL;
225        vmemmap_buf_end = NULL;
226    }
227}
228

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