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TOMOYO Linux Cross Reference
Linux/arch/x86/mm/init_32.c

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  1 /*
  2  *
  3  *  Copyright (C) 1995  Linus Torvalds
  4  *
  5  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
  6  */
  7 
  8 #include <linux/signal.h>
  9 #include <linux/sched.h>
 10 #include <linux/kernel.h>
 11 #include <linux/errno.h>
 12 #include <linux/string.h>
 13 #include <linux/types.h>
 14 #include <linux/ptrace.h>
 15 #include <linux/mman.h>
 16 #include <linux/mm.h>
 17 #include <linux/hugetlb.h>
 18 #include <linux/swap.h>
 19 #include <linux/smp.h>
 20 #include <linux/init.h>
 21 #include <linux/highmem.h>
 22 #include <linux/pagemap.h>
 23 #include <linux/pci.h>
 24 #include <linux/pfn.h>
 25 #include <linux/poison.h>
 26 #include <linux/bootmem.h>
 27 #include <linux/memblock.h>
 28 #include <linux/proc_fs.h>
 29 #include <linux/memory_hotplug.h>
 30 #include <linux/initrd.h>
 31 #include <linux/cpumask.h>
 32 #include <linux/gfp.h>
 33 
 34 #include <asm/asm.h>
 35 #include <asm/bios_ebda.h>
 36 #include <asm/processor.h>
 37 #include <linux/uaccess.h>
 38 #include <asm/pgtable.h>
 39 #include <asm/dma.h>
 40 #include <asm/fixmap.h>
 41 #include <asm/e820.h>
 42 #include <asm/apic.h>
 43 #include <asm/bugs.h>
 44 #include <asm/tlb.h>
 45 #include <asm/tlbflush.h>
 46 #include <asm/olpc_ofw.h>
 47 #include <asm/pgalloc.h>
 48 #include <asm/sections.h>
 49 #include <asm/paravirt.h>
 50 #include <asm/setup.h>
 51 #include <asm/cacheflush.h>
 52 #include <asm/page_types.h>
 53 #include <asm/init.h>
 54 
 55 #include "mm_internal.h"
 56 
 57 unsigned long highstart_pfn, highend_pfn;
 58 
 59 static noinline int do_test_wp_bit(void);
 60 
 61 bool __read_mostly __vmalloc_start_set = false;
 62 
 63 /*
 64  * Creates a middle page table and puts a pointer to it in the
 65  * given global directory entry. This only returns the gd entry
 66  * in non-PAE compilation mode, since the middle layer is folded.
 67  */
 68 static pmd_t * __init one_md_table_init(pgd_t *pgd)
 69 {
 70         pud_t *pud;
 71         pmd_t *pmd_table;
 72 
 73 #ifdef CONFIG_X86_PAE
 74         if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
 75                 pmd_table = (pmd_t *)alloc_low_page();
 76                 paravirt_alloc_pmd(&init_mm, __pa(pmd_table) >> PAGE_SHIFT);
 77                 set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
 78                 pud = pud_offset(pgd, 0);
 79                 BUG_ON(pmd_table != pmd_offset(pud, 0));
 80 
 81                 return pmd_table;
 82         }
 83 #endif
 84         pud = pud_offset(pgd, 0);
 85         pmd_table = pmd_offset(pud, 0);
 86 
 87         return pmd_table;
 88 }
 89 
 90 /*
 91  * Create a page table and place a pointer to it in a middle page
 92  * directory entry:
 93  */
 94 static pte_t * __init one_page_table_init(pmd_t *pmd)
 95 {
 96         if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
 97                 pte_t *page_table = (pte_t *)alloc_low_page();
 98 
 99                 paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);
100                 set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
101                 BUG_ON(page_table != pte_offset_kernel(pmd, 0));
102         }
103 
104         return pte_offset_kernel(pmd, 0);
105 }
106 
107 pmd_t * __init populate_extra_pmd(unsigned long vaddr)
108 {
109         int pgd_idx = pgd_index(vaddr);
110         int pmd_idx = pmd_index(vaddr);
111 
112         return one_md_table_init(swapper_pg_dir + pgd_idx) + pmd_idx;
113 }
114 
115 pte_t * __init populate_extra_pte(unsigned long vaddr)
116 {
117         int pte_idx = pte_index(vaddr);
118         pmd_t *pmd;
119 
120         pmd = populate_extra_pmd(vaddr);
121         return one_page_table_init(pmd) + pte_idx;
122 }
123 
124 static unsigned long __init
125 page_table_range_init_count(unsigned long start, unsigned long end)
126 {
127         unsigned long count = 0;
128 #ifdef CONFIG_HIGHMEM
129         int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
130         int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
131         int pgd_idx, pmd_idx;
132         unsigned long vaddr;
133 
134         if (pmd_idx_kmap_begin == pmd_idx_kmap_end)
135                 return 0;
136 
137         vaddr = start;
138         pgd_idx = pgd_index(vaddr);
139         pmd_idx = pmd_index(vaddr);
140 
141         for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd_idx++) {
142                 for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
143                                                         pmd_idx++) {
144                         if ((vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin &&
145                             (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end)
146                                 count++;
147                         vaddr += PMD_SIZE;
148                 }
149                 pmd_idx = 0;
150         }
151 #endif
152         return count;
153 }
154 
155 static pte_t *__init page_table_kmap_check(pte_t *pte, pmd_t *pmd,
156                                            unsigned long vaddr, pte_t *lastpte,
157                                            void **adr)
158 {
159 #ifdef CONFIG_HIGHMEM
160         /*
161          * Something (early fixmap) may already have put a pte
162          * page here, which causes the page table allocation
163          * to become nonlinear. Attempt to fix it, and if it
164          * is still nonlinear then we have to bug.
165          */
166         int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
167         int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
168 
169         if (pmd_idx_kmap_begin != pmd_idx_kmap_end
170             && (vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin
171             && (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end) {
172                 pte_t *newpte;
173                 int i;
174 
175                 BUG_ON(after_bootmem);
176                 newpte = *adr;
177                 for (i = 0; i < PTRS_PER_PTE; i++)
178                         set_pte(newpte + i, pte[i]);
179                 *adr = (void *)(((unsigned long)(*adr)) + PAGE_SIZE);
180 
181                 paravirt_alloc_pte(&init_mm, __pa(newpte) >> PAGE_SHIFT);
182                 set_pmd(pmd, __pmd(__pa(newpte)|_PAGE_TABLE));
183                 BUG_ON(newpte != pte_offset_kernel(pmd, 0));
184                 __flush_tlb_all();
185 
186                 paravirt_release_pte(__pa(pte) >> PAGE_SHIFT);
187                 pte = newpte;
188         }
189         BUG_ON(vaddr < fix_to_virt(FIX_KMAP_BEGIN - 1)
190                && vaddr > fix_to_virt(FIX_KMAP_END)
191                && lastpte && lastpte + PTRS_PER_PTE != pte);
192 #endif
193         return pte;
194 }
195 
196 /*
197  * This function initializes a certain range of kernel virtual memory
198  * with new bootmem page tables, everywhere page tables are missing in
199  * the given range.
200  *
201  * NOTE: The pagetables are allocated contiguous on the physical space
202  * so we can cache the place of the first one and move around without
203  * checking the pgd every time.
204  */
205 static void __init
206 page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd_base)
207 {
208         int pgd_idx, pmd_idx;
209         unsigned long vaddr;
210         pgd_t *pgd;
211         pmd_t *pmd;
212         pte_t *pte = NULL;
213         unsigned long count = page_table_range_init_count(start, end);
214         void *adr = NULL;
215 
216         if (count)
217                 adr = alloc_low_pages(count);
218 
219         vaddr = start;
220         pgd_idx = pgd_index(vaddr);
221         pmd_idx = pmd_index(vaddr);
222         pgd = pgd_base + pgd_idx;
223 
224         for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
225                 pmd = one_md_table_init(pgd);
226                 pmd = pmd + pmd_index(vaddr);
227                 for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
228                                                         pmd++, pmd_idx++) {
229                         pte = page_table_kmap_check(one_page_table_init(pmd),
230                                                     pmd, vaddr, pte, &adr);
231 
232                         vaddr += PMD_SIZE;
233                 }
234                 pmd_idx = 0;
235         }
236 }
237 
238 static inline int is_kernel_text(unsigned long addr)
239 {
240         if (addr >= (unsigned long)_text && addr <= (unsigned long)__init_end)
241                 return 1;
242         return 0;
243 }
244 
245 /*
246  * This maps the physical memory to kernel virtual address space, a total
247  * of max_low_pfn pages, by creating page tables starting from address
248  * PAGE_OFFSET:
249  */
250 unsigned long __init
251 kernel_physical_mapping_init(unsigned long start,
252                              unsigned long end,
253                              unsigned long page_size_mask)
254 {
255         int use_pse = page_size_mask == (1<<PG_LEVEL_2M);
256         unsigned long last_map_addr = end;
257         unsigned long start_pfn, end_pfn;
258         pgd_t *pgd_base = swapper_pg_dir;
259         int pgd_idx, pmd_idx, pte_ofs;
260         unsigned long pfn;
261         pgd_t *pgd;
262         pmd_t *pmd;
263         pte_t *pte;
264         unsigned pages_2m, pages_4k;
265         int mapping_iter;
266 
267         start_pfn = start >> PAGE_SHIFT;
268         end_pfn = end >> PAGE_SHIFT;
269 
270         /*
271          * First iteration will setup identity mapping using large/small pages
272          * based on use_pse, with other attributes same as set by
273          * the early code in head_32.S
274          *
275          * Second iteration will setup the appropriate attributes (NX, GLOBAL..)
276          * as desired for the kernel identity mapping.
277          *
278          * This two pass mechanism conforms to the TLB app note which says:
279          *
280          *     "Software should not write to a paging-structure entry in a way
281          *      that would change, for any linear address, both the page size
282          *      and either the page frame or attributes."
283          */
284         mapping_iter = 1;
285 
286         if (!boot_cpu_has(X86_FEATURE_PSE))
287                 use_pse = 0;
288 
289 repeat:
290         pages_2m = pages_4k = 0;
291         pfn = start_pfn;
292         pgd_idx = pgd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
293         pgd = pgd_base + pgd_idx;
294         for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
295                 pmd = one_md_table_init(pgd);
296 
297                 if (pfn >= end_pfn)
298                         continue;
299 #ifdef CONFIG_X86_PAE
300                 pmd_idx = pmd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
301                 pmd += pmd_idx;
302 #else
303                 pmd_idx = 0;
304 #endif
305                 for (; pmd_idx < PTRS_PER_PMD && pfn < end_pfn;
306                      pmd++, pmd_idx++) {
307                         unsigned int addr = pfn * PAGE_SIZE + PAGE_OFFSET;
308 
309                         /*
310                          * Map with big pages if possible, otherwise
311                          * create normal page tables:
312                          */
313                         if (use_pse) {
314                                 unsigned int addr2;
315                                 pgprot_t prot = PAGE_KERNEL_LARGE;
316                                 /*
317                                  * first pass will use the same initial
318                                  * identity mapping attribute + _PAGE_PSE.
319                                  */
320                                 pgprot_t init_prot =
321                                         __pgprot(PTE_IDENT_ATTR |
322                                                  _PAGE_PSE);
323 
324                                 pfn &= PMD_MASK >> PAGE_SHIFT;
325                                 addr2 = (pfn + PTRS_PER_PTE-1) * PAGE_SIZE +
326                                         PAGE_OFFSET + PAGE_SIZE-1;
327 
328                                 if (is_kernel_text(addr) ||
329                                     is_kernel_text(addr2))
330                                         prot = PAGE_KERNEL_LARGE_EXEC;
331 
332                                 pages_2m++;
333                                 if (mapping_iter == 1)
334                                         set_pmd(pmd, pfn_pmd(pfn, init_prot));
335                                 else
336                                         set_pmd(pmd, pfn_pmd(pfn, prot));
337 
338                                 pfn += PTRS_PER_PTE;
339                                 continue;
340                         }
341                         pte = one_page_table_init(pmd);
342 
343                         pte_ofs = pte_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
344                         pte += pte_ofs;
345                         for (; pte_ofs < PTRS_PER_PTE && pfn < end_pfn;
346                              pte++, pfn++, pte_ofs++, addr += PAGE_SIZE) {
347                                 pgprot_t prot = PAGE_KERNEL;
348                                 /*
349                                  * first pass will use the same initial
350                                  * identity mapping attribute.
351                                  */
352                                 pgprot_t init_prot = __pgprot(PTE_IDENT_ATTR);
353 
354                                 if (is_kernel_text(addr))
355                                         prot = PAGE_KERNEL_EXEC;
356 
357                                 pages_4k++;
358                                 if (mapping_iter == 1) {
359                                         set_pte(pte, pfn_pte(pfn, init_prot));
360                                         last_map_addr = (pfn << PAGE_SHIFT) + PAGE_SIZE;
361                                 } else
362                                         set_pte(pte, pfn_pte(pfn, prot));
363                         }
364                 }
365         }
366         if (mapping_iter == 1) {
367                 /*
368                  * update direct mapping page count only in the first
369                  * iteration.
370                  */
371                 update_page_count(PG_LEVEL_2M, pages_2m);
372                 update_page_count(PG_LEVEL_4K, pages_4k);
373 
374                 /*
375                  * local global flush tlb, which will flush the previous
376                  * mappings present in both small and large page TLB's.
377                  */
378                 __flush_tlb_all();
379 
380                 /*
381                  * Second iteration will set the actual desired PTE attributes.
382                  */
383                 mapping_iter = 2;
384                 goto repeat;
385         }
386         return last_map_addr;
387 }
388 
389 pte_t *kmap_pte;
390 
391 static inline pte_t *kmap_get_fixmap_pte(unsigned long vaddr)
392 {
393         return pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr),
394                         vaddr), vaddr), vaddr);
395 }
396 
397 static void __init kmap_init(void)
398 {
399         unsigned long kmap_vstart;
400 
401         /*
402          * Cache the first kmap pte:
403          */
404         kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
405         kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
406 }
407 
408 #ifdef CONFIG_HIGHMEM
409 static void __init permanent_kmaps_init(pgd_t *pgd_base)
410 {
411         unsigned long vaddr;
412         pgd_t *pgd;
413         pud_t *pud;
414         pmd_t *pmd;
415         pte_t *pte;
416 
417         vaddr = PKMAP_BASE;
418         page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
419 
420         pgd = swapper_pg_dir + pgd_index(vaddr);
421         pud = pud_offset(pgd, vaddr);
422         pmd = pmd_offset(pud, vaddr);
423         pte = pte_offset_kernel(pmd, vaddr);
424         pkmap_page_table = pte;
425 }
426 
427 void __init add_highpages_with_active_regions(int nid,
428                          unsigned long start_pfn, unsigned long end_pfn)
429 {
430         phys_addr_t start, end;
431         u64 i;
432 
433         for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &start, &end, NULL) {
434                 unsigned long pfn = clamp_t(unsigned long, PFN_UP(start),
435                                             start_pfn, end_pfn);
436                 unsigned long e_pfn = clamp_t(unsigned long, PFN_DOWN(end),
437                                               start_pfn, end_pfn);
438                 for ( ; pfn < e_pfn; pfn++)
439                         if (pfn_valid(pfn))
440                                 free_highmem_page(pfn_to_page(pfn));
441         }
442 }
443 #else
444 static inline void permanent_kmaps_init(pgd_t *pgd_base)
445 {
446 }
447 #endif /* CONFIG_HIGHMEM */
448 
449 void __init native_pagetable_init(void)
450 {
451         unsigned long pfn, va;
452         pgd_t *pgd, *base = swapper_pg_dir;
453         pud_t *pud;
454         pmd_t *pmd;
455         pte_t *pte;
456 
457         /*
458          * Remove any mappings which extend past the end of physical
459          * memory from the boot time page table.
460          * In virtual address space, we should have at least two pages
461          * from VMALLOC_END to pkmap or fixmap according to VMALLOC_END
462          * definition. And max_low_pfn is set to VMALLOC_END physical
463          * address. If initial memory mapping is doing right job, we
464          * should have pte used near max_low_pfn or one pmd is not present.
465          */
466         for (pfn = max_low_pfn; pfn < 1<<(32-PAGE_SHIFT); pfn++) {
467                 va = PAGE_OFFSET + (pfn<<PAGE_SHIFT);
468                 pgd = base + pgd_index(va);
469                 if (!pgd_present(*pgd))
470                         break;
471 
472                 pud = pud_offset(pgd, va);
473                 pmd = pmd_offset(pud, va);
474                 if (!pmd_present(*pmd))
475                         break;
476 
477                 /* should not be large page here */
478                 if (pmd_large(*pmd)) {
479                         pr_warn("try to clear pte for ram above max_low_pfn: pfn: %lx pmd: %p pmd phys: %lx, but pmd is big page and is not using pte !\n",
480                                 pfn, pmd, __pa(pmd));
481                         BUG_ON(1);
482                 }
483 
484                 pte = pte_offset_kernel(pmd, va);
485                 if (!pte_present(*pte))
486                         break;
487 
488                 printk(KERN_DEBUG "clearing pte for ram above max_low_pfn: pfn: %lx pmd: %p pmd phys: %lx pte: %p pte phys: %lx\n",
489                                 pfn, pmd, __pa(pmd), pte, __pa(pte));
490                 pte_clear(NULL, va, pte);
491         }
492         paravirt_alloc_pmd(&init_mm, __pa(base) >> PAGE_SHIFT);
493         paging_init();
494 }
495 
496 /*
497  * Build a proper pagetable for the kernel mappings.  Up until this
498  * point, we've been running on some set of pagetables constructed by
499  * the boot process.
500  *
501  * If we're booting on native hardware, this will be a pagetable
502  * constructed in arch/x86/kernel/head_32.S.  The root of the
503  * pagetable will be swapper_pg_dir.
504  *
505  * If we're booting paravirtualized under a hypervisor, then there are
506  * more options: we may already be running PAE, and the pagetable may
507  * or may not be based in swapper_pg_dir.  In any case,
508  * paravirt_pagetable_init() will set up swapper_pg_dir
509  * appropriately for the rest of the initialization to work.
510  *
511  * In general, pagetable_init() assumes that the pagetable may already
512  * be partially populated, and so it avoids stomping on any existing
513  * mappings.
514  */
515 void __init early_ioremap_page_table_range_init(void)
516 {
517         pgd_t *pgd_base = swapper_pg_dir;
518         unsigned long vaddr, end;
519 
520         /*
521          * Fixed mappings, only the page table structure has to be
522          * created - mappings will be set by set_fixmap():
523          */
524         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
525         end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
526         page_table_range_init(vaddr, end, pgd_base);
527         early_ioremap_reset();
528 }
529 
530 static void __init pagetable_init(void)
531 {
532         pgd_t *pgd_base = swapper_pg_dir;
533 
534         permanent_kmaps_init(pgd_base);
535 }
536 
537 pteval_t __supported_pte_mask __read_mostly = ~(_PAGE_NX | _PAGE_GLOBAL);
538 EXPORT_SYMBOL_GPL(__supported_pte_mask);
539 
540 /* user-defined highmem size */
541 static unsigned int highmem_pages = -1;
542 
543 /*
544  * highmem=size forces highmem to be exactly 'size' bytes.
545  * This works even on boxes that have no highmem otherwise.
546  * This also works to reduce highmem size on bigger boxes.
547  */
548 static int __init parse_highmem(char *arg)
549 {
550         if (!arg)
551                 return -EINVAL;
552 
553         highmem_pages = memparse(arg, &arg) >> PAGE_SHIFT;
554         return 0;
555 }
556 early_param("highmem", parse_highmem);
557 
558 #define MSG_HIGHMEM_TOO_BIG \
559         "highmem size (%luMB) is bigger than pages available (%luMB)!\n"
560 
561 #define MSG_LOWMEM_TOO_SMALL \
562         "highmem size (%luMB) results in <64MB lowmem, ignoring it!\n"
563 /*
564  * All of RAM fits into lowmem - but if user wants highmem
565  * artificially via the highmem=x boot parameter then create
566  * it:
567  */
568 static void __init lowmem_pfn_init(void)
569 {
570         /* max_low_pfn is 0, we already have early_res support */
571         max_low_pfn = max_pfn;
572 
573         if (highmem_pages == -1)
574                 highmem_pages = 0;
575 #ifdef CONFIG_HIGHMEM
576         if (highmem_pages >= max_pfn) {
577                 printk(KERN_ERR MSG_HIGHMEM_TOO_BIG,
578                         pages_to_mb(highmem_pages), pages_to_mb(max_pfn));
579                 highmem_pages = 0;
580         }
581         if (highmem_pages) {
582                 if (max_low_pfn - highmem_pages < 64*1024*1024/PAGE_SIZE) {
583                         printk(KERN_ERR MSG_LOWMEM_TOO_SMALL,
584                                 pages_to_mb(highmem_pages));
585                         highmem_pages = 0;
586                 }
587                 max_low_pfn -= highmem_pages;
588         }
589 #else
590         if (highmem_pages)
591                 printk(KERN_ERR "ignoring highmem size on non-highmem kernel!\n");
592 #endif
593 }
594 
595 #define MSG_HIGHMEM_TOO_SMALL \
596         "only %luMB highmem pages available, ignoring highmem size of %luMB!\n"
597 
598 #define MSG_HIGHMEM_TRIMMED \
599         "Warning: only 4GB will be used. Use a HIGHMEM64G enabled kernel!\n"
600 /*
601  * We have more RAM than fits into lowmem - we try to put it into
602  * highmem, also taking the highmem=x boot parameter into account:
603  */
604 static void __init highmem_pfn_init(void)
605 {
606         max_low_pfn = MAXMEM_PFN;
607 
608         if (highmem_pages == -1)
609                 highmem_pages = max_pfn - MAXMEM_PFN;
610 
611         if (highmem_pages + MAXMEM_PFN < max_pfn)
612                 max_pfn = MAXMEM_PFN + highmem_pages;
613 
614         if (highmem_pages + MAXMEM_PFN > max_pfn) {
615                 printk(KERN_WARNING MSG_HIGHMEM_TOO_SMALL,
616                         pages_to_mb(max_pfn - MAXMEM_PFN),
617                         pages_to_mb(highmem_pages));
618                 highmem_pages = 0;
619         }
620 #ifndef CONFIG_HIGHMEM
621         /* Maximum memory usable is what is directly addressable */
622         printk(KERN_WARNING "Warning only %ldMB will be used.\n", MAXMEM>>20);
623         if (max_pfn > MAX_NONPAE_PFN)
624                 printk(KERN_WARNING "Use a HIGHMEM64G enabled kernel.\n");
625         else
626                 printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
627         max_pfn = MAXMEM_PFN;
628 #else /* !CONFIG_HIGHMEM */
629 #ifndef CONFIG_HIGHMEM64G
630         if (max_pfn > MAX_NONPAE_PFN) {
631                 max_pfn = MAX_NONPAE_PFN;
632                 printk(KERN_WARNING MSG_HIGHMEM_TRIMMED);
633         }
634 #endif /* !CONFIG_HIGHMEM64G */
635 #endif /* !CONFIG_HIGHMEM */
636 }
637 
638 /*
639  * Determine low and high memory ranges:
640  */
641 void __init find_low_pfn_range(void)
642 {
643         /* it could update max_pfn */
644 
645         if (max_pfn <= MAXMEM_PFN)
646                 lowmem_pfn_init();
647         else
648                 highmem_pfn_init();
649 }
650 
651 #ifndef CONFIG_NEED_MULTIPLE_NODES
652 void __init initmem_init(void)
653 {
654 #ifdef CONFIG_HIGHMEM
655         highstart_pfn = highend_pfn = max_pfn;
656         if (max_pfn > max_low_pfn)
657                 highstart_pfn = max_low_pfn;
658         printk(KERN_NOTICE "%ldMB HIGHMEM available.\n",
659                 pages_to_mb(highend_pfn - highstart_pfn));
660         high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
661 #else
662         high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
663 #endif
664 
665         memblock_set_node(0, (phys_addr_t)ULLONG_MAX, &memblock.memory, 0);
666         sparse_memory_present_with_active_regions(0);
667 
668 #ifdef CONFIG_FLATMEM
669         max_mapnr = IS_ENABLED(CONFIG_HIGHMEM) ? highend_pfn : max_low_pfn;
670 #endif
671         __vmalloc_start_set = true;
672 
673         printk(KERN_NOTICE "%ldMB LOWMEM available.\n",
674                         pages_to_mb(max_low_pfn));
675 
676         setup_bootmem_allocator();
677 }
678 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
679 
680 void __init setup_bootmem_allocator(void)
681 {
682         printk(KERN_INFO "  mapped low ram: 0 - %08lx\n",
683                  max_pfn_mapped<<PAGE_SHIFT);
684         printk(KERN_INFO "  low ram: 0 - %08lx\n", max_low_pfn<<PAGE_SHIFT);
685 }
686 
687 /*
688  * paging_init() sets up the page tables - note that the first 8MB are
689  * already mapped by head.S.
690  *
691  * This routines also unmaps the page at virtual kernel address 0, so
692  * that we can trap those pesky NULL-reference errors in the kernel.
693  */
694 void __init paging_init(void)
695 {
696         pagetable_init();
697 
698         __flush_tlb_all();
699 
700         kmap_init();
701 
702         /*
703          * NOTE: at this point the bootmem allocator is fully available.
704          */
705         olpc_dt_build_devicetree();
706         sparse_memory_present_with_active_regions(MAX_NUMNODES);
707         sparse_init();
708         zone_sizes_init();
709 }
710 
711 /*
712  * Test if the WP bit works in supervisor mode. It isn't supported on 386's
713  * and also on some strange 486's. All 586+'s are OK. This used to involve
714  * black magic jumps to work around some nasty CPU bugs, but fortunately the
715  * switch to using exceptions got rid of all that.
716  */
717 static void __init test_wp_bit(void)
718 {
719         printk(KERN_INFO
720   "Checking if this processor honours the WP bit even in supervisor mode...");
721 
722         /* Any page-aligned address will do, the test is non-destructive */
723         __set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_KERNEL_RO);
724         boot_cpu_data.wp_works_ok = do_test_wp_bit();
725         clear_fixmap(FIX_WP_TEST);
726 
727         if (!boot_cpu_data.wp_works_ok) {
728                 printk(KERN_CONT "No.\n");
729                 panic("Linux doesn't support CPUs with broken WP.");
730         } else {
731                 printk(KERN_CONT "Ok.\n");
732         }
733 }
734 
735 void __init mem_init(void)
736 {
737         pci_iommu_alloc();
738 
739 #ifdef CONFIG_FLATMEM
740         BUG_ON(!mem_map);
741 #endif
742         /*
743          * With CONFIG_DEBUG_PAGEALLOC initialization of highmem pages has to
744          * be done before free_all_bootmem(). Memblock use free low memory for
745          * temporary data (see find_range_array()) and for this purpose can use
746          * pages that was already passed to the buddy allocator, hence marked as
747          * not accessible in the page tables when compiled with
748          * CONFIG_DEBUG_PAGEALLOC. Otherwise order of initialization is not
749          * important here.
750          */
751         set_highmem_pages_init();
752 
753         /* this will put all low memory onto the freelists */
754         free_all_bootmem();
755 
756         after_bootmem = 1;
757 
758         mem_init_print_info(NULL);
759         printk(KERN_INFO "virtual kernel memory layout:\n"
760                 "    fixmap  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
761 #ifdef CONFIG_HIGHMEM
762                 "    pkmap   : 0x%08lx - 0x%08lx   (%4ld kB)\n"
763 #endif
764                 "    vmalloc : 0x%08lx - 0x%08lx   (%4ld MB)\n"
765                 "    lowmem  : 0x%08lx - 0x%08lx   (%4ld MB)\n"
766                 "      .init : 0x%08lx - 0x%08lx   (%4ld kB)\n"
767                 "      .data : 0x%08lx - 0x%08lx   (%4ld kB)\n"
768                 "      .text : 0x%08lx - 0x%08lx   (%4ld kB)\n",
769                 FIXADDR_START, FIXADDR_TOP,
770                 (FIXADDR_TOP - FIXADDR_START) >> 10,
771 
772 #ifdef CONFIG_HIGHMEM
773                 PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE,
774                 (LAST_PKMAP*PAGE_SIZE) >> 10,
775 #endif
776 
777                 VMALLOC_START, VMALLOC_END,
778                 (VMALLOC_END - VMALLOC_START) >> 20,
779 
780                 (unsigned long)__va(0), (unsigned long)high_memory,
781                 ((unsigned long)high_memory - (unsigned long)__va(0)) >> 20,
782 
783                 (unsigned long)&__init_begin, (unsigned long)&__init_end,
784                 ((unsigned long)&__init_end -
785                  (unsigned long)&__init_begin) >> 10,
786 
787                 (unsigned long)&_etext, (unsigned long)&_edata,
788                 ((unsigned long)&_edata - (unsigned long)&_etext) >> 10,
789 
790                 (unsigned long)&_text, (unsigned long)&_etext,
791                 ((unsigned long)&_etext - (unsigned long)&_text) >> 10);
792 
793         /*
794          * Check boundaries twice: Some fundamental inconsistencies can
795          * be detected at build time already.
796          */
797 #define __FIXADDR_TOP (-PAGE_SIZE)
798 #ifdef CONFIG_HIGHMEM
799         BUILD_BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE  > FIXADDR_START);
800         BUILD_BUG_ON(VMALLOC_END                        > PKMAP_BASE);
801 #endif
802 #define high_memory (-128UL << 20)
803         BUILD_BUG_ON(VMALLOC_START                      >= VMALLOC_END);
804 #undef high_memory
805 #undef __FIXADDR_TOP
806 
807 #ifdef CONFIG_HIGHMEM
808         BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE        > FIXADDR_START);
809         BUG_ON(VMALLOC_END                              > PKMAP_BASE);
810 #endif
811         BUG_ON(VMALLOC_START                            >= VMALLOC_END);
812         BUG_ON((unsigned long)high_memory               > VMALLOC_START);
813 
814         if (boot_cpu_data.wp_works_ok < 0)
815                 test_wp_bit();
816 }
817 
818 #ifdef CONFIG_MEMORY_HOTPLUG
819 int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
820 {
821         struct pglist_data *pgdata = NODE_DATA(nid);
822         struct zone *zone = pgdata->node_zones +
823                 zone_for_memory(nid, start, size, ZONE_HIGHMEM, for_device);
824         unsigned long start_pfn = start >> PAGE_SHIFT;
825         unsigned long nr_pages = size >> PAGE_SHIFT;
826 
827         return __add_pages(nid, zone, start_pfn, nr_pages);
828 }
829 
830 #ifdef CONFIG_MEMORY_HOTREMOVE
831 int arch_remove_memory(u64 start, u64 size)
832 {
833         unsigned long start_pfn = start >> PAGE_SHIFT;
834         unsigned long nr_pages = size >> PAGE_SHIFT;
835         struct zone *zone;
836 
837         zone = page_zone(pfn_to_page(start_pfn));
838         return __remove_pages(zone, start_pfn, nr_pages);
839 }
840 #endif
841 #endif
842 
843 /*
844  * This function cannot be __init, since exceptions don't work in that
845  * section.  Put this after the callers, so that it cannot be inlined.
846  */
847 static noinline int do_test_wp_bit(void)
848 {
849         char tmp_reg;
850         int flag;
851 
852         __asm__ __volatile__(
853                 "       movb %0, %1     \n"
854                 "1:     movb %1, %0     \n"
855                 "       xorl %2, %2     \n"
856                 "2:                     \n"
857                 _ASM_EXTABLE(1b,2b)
858                 :"=m" (*(char *)fix_to_virt(FIX_WP_TEST)),
859                  "=q" (tmp_reg),
860                  "=r" (flag)
861                 :"2" (1)
862                 :"memory");
863 
864         return flag;
865 }
866 
867 const int rodata_test_data = 0xC3;
868 EXPORT_SYMBOL_GPL(rodata_test_data);
869 
870 int kernel_set_to_readonly __read_mostly;
871 
872 void set_kernel_text_rw(void)
873 {
874         unsigned long start = PFN_ALIGN(_text);
875         unsigned long size = PFN_ALIGN(_etext) - start;
876 
877         if (!kernel_set_to_readonly)
878                 return;
879 
880         pr_debug("Set kernel text: %lx - %lx for read write\n",
881                  start, start+size);
882 
883         set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
884 }
885 
886 void set_kernel_text_ro(void)
887 {
888         unsigned long start = PFN_ALIGN(_text);
889         unsigned long size = PFN_ALIGN(_etext) - start;
890 
891         if (!kernel_set_to_readonly)
892                 return;
893 
894         pr_debug("Set kernel text: %lx - %lx for read only\n",
895                  start, start+size);
896 
897         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
898 }
899 
900 static void mark_nxdata_nx(void)
901 {
902         /*
903          * When this called, init has already been executed and released,
904          * so everything past _etext should be NX.
905          */
906         unsigned long start = PFN_ALIGN(_etext);
907         /*
908          * This comes from is_kernel_text upper limit. Also HPAGE where used:
909          */
910         unsigned long size = (((unsigned long)__init_end + HPAGE_SIZE) & HPAGE_MASK) - start;
911 
912         if (__supported_pte_mask & _PAGE_NX)
913                 printk(KERN_INFO "NX-protecting the kernel data: %luk\n", size >> 10);
914         set_pages_nx(virt_to_page(start), size >> PAGE_SHIFT);
915 }
916 
917 void mark_rodata_ro(void)
918 {
919         unsigned long start = PFN_ALIGN(_text);
920         unsigned long size = PFN_ALIGN(_etext) - start;
921 
922         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
923         printk(KERN_INFO "Write protecting the kernel text: %luk\n",
924                 size >> 10);
925 
926         kernel_set_to_readonly = 1;
927 
928 #ifdef CONFIG_CPA_DEBUG
929         printk(KERN_INFO "Testing CPA: Reverting %lx-%lx\n",
930                 start, start+size);
931         set_pages_rw(virt_to_page(start), size>>PAGE_SHIFT);
932 
933         printk(KERN_INFO "Testing CPA: write protecting again\n");
934         set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
935 #endif
936 
937         start += size;
938         size = (unsigned long)__end_rodata - start;
939         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
940         printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
941                 size >> 10);
942         rodata_test();
943 
944 #ifdef CONFIG_CPA_DEBUG
945         printk(KERN_INFO "Testing CPA: undo %lx-%lx\n", start, start + size);
946         set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
947 
948         printk(KERN_INFO "Testing CPA: write protecting again\n");
949         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
950 #endif
951         mark_nxdata_nx();
952         if (__supported_pte_mask & _PAGE_NX)
953                 debug_checkwx();
954 }
955 

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