Linux Kernel  3.7.1
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init.c
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1 /*
2  * Memory subsystem initialization for Hexagon
3  *
4  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 and
8  * only version 2 as published by the Free Software Foundation.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
18  * 02110-1301, USA.
19  */
20 
21 #include <linux/init.h>
22 #include <linux/mm.h>
23 #include <linux/bootmem.h>
24 #include <asm/atomic.h>
25 #include <linux/highmem.h>
26 #include <asm/tlb.h>
27 #include <asm/sections.h>
28 #include <asm/vm_mmu.h>
29 
30 /*
31  * Define a startpg just past the end of the kernel image and a lastpg
32  * that corresponds to the end of real or simulated platform memory.
33  */
34 #define bootmem_startpg (PFN_UP(((unsigned long) _end) - PAGE_OFFSET))
35 
36 unsigned long bootmem_lastpg; /* Should be set by platform code */
37 
38 /* Set as variable to limit PMD copies */
39 int max_kernel_seg = 0x303;
40 
41 /* think this should be (page_size-1) the way it's used...*/
42 unsigned long zero_page_mask;
43 
44 /* indicate pfn's of high memory */
45 unsigned long highstart_pfn, highend_pfn;
46 
47 /* struct mmu_gather defined in asm-generic.h; */
48 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
49 
50 /* Default cache attribute for newly created page tables */
51 unsigned long _dflt_cache_att = CACHEDEF;
52 
53 /*
54  * The current "generation" of kernel map, which should not roll
55  * over until Hell freezes over. Actual bound in years needs to be
56  * calculated to confirm.
57  */
58 DEFINE_SPINLOCK(kmap_gen_lock);
59 
60 /* checkpatch says don't init this to 0. */
61 unsigned long long kmap_generation;
62 
63 /*
64  * mem_init - initializes memory
65  *
66  * Frees up bootmem
67  * Fixes up more stuff for HIGHMEM
68  * Calculates and displays memory available/used
69  */
70 void __init mem_init(void)
71 {
72  /* No idea where this is actually declared. Seems to evade LXR. */
73  totalram_pages += free_all_bootmem();
74  num_physpages = bootmem_lastpg; /* seriously, what? */
75 
76  printk(KERN_INFO "totalram_pages = %ld\n", totalram_pages);
77 
78  /*
79  * To-Do: someone somewhere should wipe out the bootmem map
80  * after we're done?
81  */
82 
83  /*
84  * This can be moved to some more virtual-memory-specific
85  * initialization hook at some point. Set the init_mm
86  * descriptors "context" value to point to the initial
87  * kernel segment table's physical address.
88  */
89  init_mm.context.ptbase = __pa(init_mm.pgd);
90 }
91 
92 /*
93  * free_initmem - frees memory used by stuff declared with __init
94  *
95  * Todo: free pages between __init_begin and __init_end; possibly
96  * some devtree related stuff as well.
97  */
99 {
100 }
101 
102 /*
103  * free_initrd_mem - frees... initrd memory.
104  * @start - start of init memory
105  * @end - end of init memory
106  *
107  * Apparently has to be passed the address of the initrd memory.
108  *
109  * Wrapped by #ifdef CONFIG_BLKDEV_INITRD
110  */
111 void free_initrd_mem(unsigned long start, unsigned long end)
112 {
113 }
114 
116 {
117  unsigned long addr;
118  struct page *page;
119 
120  page = pte_page(pte);
121  addr = (unsigned long) page_address(page);
122 
123  __vmcache_idsync(addr, PAGE_SIZE);
124 }
125 
126 /*
127  * In order to set up page allocator "nodes",
128  * somebody has to call free_area_init() for UMA.
129  *
130  * In this mode, we only have one pg_data_t
131  * structure: contig_mem_data.
132  */
133 void __init paging_init(void)
134 {
135  unsigned long zones_sizes[MAX_NR_ZONES] = {0, };
136 
137  /*
138  * This is not particularly well documented anywhere, but
139  * give ZONE_NORMAL all the memory, including the big holes
140  * left by the kernel+bootmem_map which are already left as reserved
141  * in the bootmem_map; free_area_init should see those bits and
142  * adjust accordingly.
143  */
144 
145  zones_sizes[ZONE_NORMAL] = max_low_pfn;
146 
147  free_area_init(zones_sizes); /* sets up the zonelists and mem_map */
148 
149  /*
150  * Start of high memory area. Will probably need something more
151  * fancy if we... get more fancy.
152  */
153  high_memory = (void *)((bootmem_lastpg + 1) << PAGE_SHIFT);
154 }
155 
156 #ifndef DMA_RESERVE
157 #define DMA_RESERVE (4)
158 #endif
159 
160 #define DMA_CHUNKSIZE (1<<22)
161 #define DMA_RESERVED_BYTES (DMA_RESERVE * DMA_CHUNKSIZE)
162 
163 /*
164  * Pick out the memory size. We look for mem=size,
165  * where size is "size[KkMm]"
166  */
167 static int __init early_mem(char *p)
168 {
169  unsigned long size;
170  char *endp;
171 
172  size = memparse(p, &endp);
173 
174  bootmem_lastpg = PFN_DOWN(size);
175 
176  return 0;
177 }
178 early_param("mem", early_mem);
179 
181 
183 {
184  int bootmap_size;
185  /* XXX Todo: this probably should be cleaned up */
186  u32 *segtable = (u32 *) &swapper_pg_dir[0];
187  u32 *segtable_end;
188 
189  /*
190  * Set up boot memory allocator
191  *
192  * The Gorman book also talks about these functions.
193  * This needs to change for highmem setups.
194  */
195 
196  /* Memory size needs to be a multiple of 16M */
198  ~((BIG_KERNEL_PAGE_SIZE) - 1));
199 
200  /*
201  * Reserve the top DMA_RESERVE bytes of RAM for DMA (uncached)
202  * memory allocation
203  */
206 
207  printk(KERN_INFO "bootmem_startpg: 0x%08lx\n", bootmem_startpg);
208  printk(KERN_INFO "bootmem_lastpg: 0x%08lx\n", bootmem_lastpg);
209  printk(KERN_INFO "bootmap_size: %d\n", bootmap_size);
210  printk(KERN_INFO "max_low_pfn: 0x%08lx\n", max_low_pfn);
211 
212  /*
213  * The default VM page tables (will be) populated with
214  * VA=PA+PAGE_OFFSET mapping. We go in and invalidate entries
215  * higher than what we have memory for.
216  */
217 
218  /* this is pointer arithmetic; each entry covers 4MB */
219  segtable = segtable + (PAGE_OFFSET >> 22);
220 
221  /* this actually only goes to the end of the first gig */
222  segtable_end = segtable + (1<<(30-22));
223 
224  /* Move forward to the start of empty pages */
225  segtable += bootmem_lastpg >> (22-PAGE_SHIFT);
226 
227  {
228  int i;
229 
230  for (i = 1 ; i <= DMA_RESERVE ; i++)
231  segtable[-i] = ((segtable[-i] & __HVM_PTE_PGMASK_4MB)
233  | __HEXAGON_C_UNC << 6
234  | __HVM_PDE_S_4MB);
235  }
236 
237  printk(KERN_INFO "clearing segtable from %p to %p\n", segtable,
238  segtable_end);
239  while (segtable < (segtable_end-8))
240  *(segtable++) = __HVM_PDE_S_INVALID;
241  /* stop the pointer at the device I/O 4MB page */
242 
243  printk(KERN_INFO "segtable = %p (should be equal to _K_io_map)\n",
244  segtable);
245 
246 #if 0
247  /* Other half of the early device table from vm_init_segtable. */
248  printk(KERN_INFO "&_K_init_devicetable = 0x%08x\n",
249  (unsigned long) _K_init_devicetable-PAGE_OFFSET);
250  *segtable = ((u32) (unsigned long) _K_init_devicetable-PAGE_OFFSET) |
252  printk(KERN_INFO "*segtable = 0x%08x\n", *segtable);
253 #endif
254 
255  /*
256  * Free all the memory that wasn't taken up by the bootmap, the DMA
257  * reserve, or kernel itself.
258  */
259  free_bootmem(PFN_PHYS(bootmem_startpg)+bootmap_size,
260  PFN_PHYS(bootmem_lastpg - bootmem_startpg) - bootmap_size -
262 
263  /*
264  * The bootmem allocator seemingly just lives to feed memory
265  * to the paging system
266  */
267  printk(KERN_INFO "PAGE_SIZE=%lu\n", PAGE_SIZE);
268  paging_init(); /* See Gorman Book, 2.3 */
269 
270  /*
271  * At this point, the page allocator is kind of initialized, but
272  * apparently no pages are available (just like with the bootmem
273  * allocator), and need to be freed themselves via mem_init(),
274  * which is called by start_kernel() later on in the process
275  */
276 }