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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/module.h>
  9 #include <linux/signal.h>
 10 #include <linux/sched.h>
 11 #include <linux/kernel.h>
 12 #include <linux/errno.h>
 13 #include <linux/string.h>
 14 #include <linux/types.h>
 15 #include <linux/ptrace.h>
 16 #include <linux/mman.h>
 17 #include <linux/mm.h>
 18 #include <linux/hugetlb.h>
 19 #include <linux/swap.h>
 20 #include <linux/smp.h>
 21 #include <linux/init.h>
 22 #include <linux/highmem.h>
 23 #include <linux/pagemap.h>
 24 #include <linux/pci.h>
 25 #include <linux/pfn.h>
 26 #include <linux/poison.h>
 27 #include <linux/bootmem.h>
 28 #include <linux/memblock.h>
 29 #include <linux/proc_fs.h>
 30 #include <linux/memory_hotplug.h>
 31 #include <linux/initrd.h>
 32 #include <linux/cpumask.h>
 33 #include <linux/gfp.h>
 34 
 35 #include <asm/asm.h>
 36 #include <asm/bios_ebda.h>
 37 #include <asm/processor.h>
 38 #include <asm/uaccess.h>
 39 #include <asm/pgtable.h>
 40 #include <asm/dma.h>
 41 #include <asm/fixmap.h>
 42 #include <asm/e820.h>
 43 #include <asm/apic.h>
 44 #include <asm/bugs.h>
 45 #include <asm/tlb.h>
 46 #include <asm/tlbflush.h>
 47 #include <asm/olpc_ofw.h>
 48 #include <asm/pgalloc.h>
 49 #include <asm/sections.h>
 50 #include <asm/paravirt.h>
 51 #include <asm/setup.h>
 52 #include <asm/cacheflush.h>
 53 #include <asm/page_types.h>
 54 #include <asm/init.h>
 55 
 56 #include "mm_internal.h"
 57 
 58 unsigned long highstart_pfn, highend_pfn;
 59 
 60 static noinline int do_test_wp_bit(void);
 61 
 62 bool __read_mostly __vmalloc_start_set = false;
 63 
 64 /*
 65  * Creates a middle page table and puts a pointer to it in the
 66  * given global directory entry. This only returns the gd entry
 67  * in non-PAE compilation mode, since the middle layer is folded.
 68  */
 69 static pmd_t * __init one_md_table_init(pgd_t *pgd)
 70 {
 71         pud_t *pud;
 72         pmd_t *pmd_table;
 73 
 74 #ifdef CONFIG_X86_PAE
 75         if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
 76                 pmd_table = (pmd_t *)alloc_low_page();
 77                 paravirt_alloc_pmd(&init_mm, __pa(pmd_table) >> PAGE_SHIFT);
 78                 set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
 79                 pud = pud_offset(pgd, 0);
 80                 BUG_ON(pmd_table != pmd_offset(pud, 0));
 81 
 82                 return pmd_table;
 83         }
 84 #endif
 85         pud = pud_offset(pgd, 0);
 86         pmd_table = pmd_offset(pud, 0);
 87 
 88         return pmd_table;
 89 }
 90 
 91 /*
 92  * Create a page table and place a pointer to it in a middle page
 93  * directory entry:
 94  */
 95 static pte_t * __init one_page_table_init(pmd_t *pmd)
 96 {
 97         if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
 98                 pte_t *page_table = (pte_t *)alloc_low_page();
 99 
100                 paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);
101                 set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
102                 BUG_ON(page_table != pte_offset_kernel(pmd, 0));
103         }
104 
105         return pte_offset_kernel(pmd, 0);
106 }
107 
108 pmd_t * __init populate_extra_pmd(unsigned long vaddr)
109 {
110         int pgd_idx = pgd_index(vaddr);
111         int pmd_idx = pmd_index(vaddr);
112 
113         return one_md_table_init(swapper_pg_dir + pgd_idx) + pmd_idx;
114 }
115 
116 pte_t * __init populate_extra_pte(unsigned long vaddr)
117 {
118         int pte_idx = pte_index(vaddr);
119         pmd_t *pmd;
120 
121         pmd = populate_extra_pmd(vaddr);
122         return one_page_table_init(pmd) + pte_idx;
123 }
124 
125 static unsigned long __init
126 page_table_range_init_count(unsigned long start, unsigned long end)
127 {
128         unsigned long count = 0;
129 #ifdef CONFIG_HIGHMEM
130         int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
131         int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
132         int pgd_idx, pmd_idx;
133         unsigned long vaddr;
134 
135         if (pmd_idx_kmap_begin == pmd_idx_kmap_end)
136                 return 0;
137 
138         vaddr = start;
139         pgd_idx = pgd_index(vaddr);
140         pmd_idx = pmd_index(vaddr);
141 
142         for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd_idx++) {
143                 for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
144                                                         pmd_idx++) {
145                         if ((vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin &&
146                             (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end)
147                                 count++;
148                         vaddr += PMD_SIZE;
149                 }
150                 pmd_idx = 0;
151         }
152 #endif
153         return count;
154 }
155 
156 static pte_t *__init page_table_kmap_check(pte_t *pte, pmd_t *pmd,
157                                            unsigned long vaddr, pte_t *lastpte,
158                                            void **adr)
159 {
160 #ifdef CONFIG_HIGHMEM
161         /*
162          * Something (early fixmap) may already have put a pte
163          * page here, which causes the page table allocation
164          * to become nonlinear. Attempt to fix it, and if it
165          * is still nonlinear then we have to bug.
166          */
167         int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
168         int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
169 
170         if (pmd_idx_kmap_begin != pmd_idx_kmap_end
171             && (vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin
172             && (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end) {
173                 pte_t *newpte;
174                 int i;
175 
176                 BUG_ON(after_bootmem);
177                 newpte = *adr;
178                 for (i = 0; i < PTRS_PER_PTE; i++)
179                         set_pte(newpte + i, pte[i]);
180                 *adr = (void *)(((unsigned long)(*adr)) + PAGE_SIZE);
181 
182                 paravirt_alloc_pte(&init_mm, __pa(newpte) >> PAGE_SHIFT);
183                 set_pmd(pmd, __pmd(__pa(newpte)|_PAGE_TABLE));
184                 BUG_ON(newpte != pte_offset_kernel(pmd, 0));
185                 __flush_tlb_all();
186 
187                 paravirt_release_pte(__pa(pte) >> PAGE_SHIFT);
188                 pte = newpte;
189         }
190         BUG_ON(vaddr < fix_to_virt(FIX_KMAP_BEGIN - 1)
191                && vaddr > fix_to_virt(FIX_KMAP_END)
192                && lastpte && lastpte + PTRS_PER_PTE != pte);
193 #endif
194         return pte;
195 }
196 
197 /*
198  * This function initializes a certain range of kernel virtual memory
199  * with new bootmem page tables, everywhere page tables are missing in
200  * the given range.
201  *
202  * NOTE: The pagetables are allocated contiguous on the physical space
203  * so we can cache the place of the first one and move around without
204  * checking the pgd every time.
205  */
206 static void __init
207 page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd_base)
208 {
209         int pgd_idx, pmd_idx;
210         unsigned long vaddr;
211         pgd_t *pgd;
212         pmd_t *pmd;
213         pte_t *pte = NULL;
214         unsigned long count = page_table_range_init_count(start, end);
215         void *adr = NULL;
216 
217         if (count)
218                 adr = alloc_low_pages(count);
219 
220         vaddr = start;
221         pgd_idx = pgd_index(vaddr);
222         pmd_idx = pmd_index(vaddr);
223         pgd = pgd_base + pgd_idx;
224 
225         for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
226                 pmd = one_md_table_init(pgd);
227                 pmd = pmd + pmd_index(vaddr);
228                 for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
229                                                         pmd++, pmd_idx++) {
230                         pte = page_table_kmap_check(one_page_table_init(pmd),
231                                                     pmd, vaddr, pte, &adr);
232 
233                         vaddr += PMD_SIZE;
234                 }
235                 pmd_idx = 0;
236         }
237 }
238 
239 static inline int is_kernel_text(unsigned long addr)
240 {
241         if (addr >= (unsigned long)_text && addr <= (unsigned long)__init_end)
242                 return 1;
243         return 0;
244 }
245 
246 /*
247  * This maps the physical memory to kernel virtual address space, a total
248  * of max_low_pfn pages, by creating page tables starting from address
249  * PAGE_OFFSET:
250  */
251 unsigned long __init
252 kernel_physical_mapping_init(unsigned long start,
253                              unsigned long end,
254                              unsigned long page_size_mask)
255 {
256         int use_pse = page_size_mask == (1<<PG_LEVEL_2M);
257         unsigned long last_map_addr = end;
258         unsigned long start_pfn, end_pfn;
259         pgd_t *pgd_base = swapper_pg_dir;
260         int pgd_idx, pmd_idx, pte_ofs;
261         unsigned long pfn;
262         pgd_t *pgd;
263         pmd_t *pmd;
264         pte_t *pte;
265         unsigned pages_2m, pages_4k;
266         int mapping_iter;
267 
268         start_pfn = start >> PAGE_SHIFT;
269         end_pfn = end >> PAGE_SHIFT;
270 
271         /*
272          * First iteration will setup identity mapping using large/small pages
273          * based on use_pse, with other attributes same as set by
274          * the early code in head_32.S
275          *
276          * Second iteration will setup the appropriate attributes (NX, GLOBAL..)
277          * as desired for the kernel identity mapping.
278          *
279          * This two pass mechanism conforms to the TLB app note which says:
280          *
281          *     "Software should not write to a paging-structure entry in a way
282          *      that would change, for any linear address, both the page size
283          *      and either the page frame or attributes."
284          */
285         mapping_iter = 1;
286 
287         if (!cpu_has_pse)
288                 use_pse = 0;
289 
290 repeat:
291         pages_2m = pages_4k = 0;
292         pfn = start_pfn;
293         pgd_idx = pgd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
294         pgd = pgd_base + pgd_idx;
295         for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
296                 pmd = one_md_table_init(pgd);
297 
298                 if (pfn >= end_pfn)
299                         continue;
300 #ifdef CONFIG_X86_PAE
301                 pmd_idx = pmd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
302                 pmd += pmd_idx;
303 #else
304                 pmd_idx = 0;
305 #endif
306                 for (; pmd_idx < PTRS_PER_PMD && pfn < end_pfn;
307                      pmd++, pmd_idx++) {
308                         unsigned int addr = pfn * PAGE_SIZE + PAGE_OFFSET;
309 
310                         /*
311                          * Map with big pages if possible, otherwise
312                          * create normal page tables:
313                          */
314                         if (use_pse) {
315                                 unsigned int addr2;
316                                 pgprot_t prot = PAGE_KERNEL_LARGE;
317                                 /*
318                                  * first pass will use the same initial
319                                  * identity mapping attribute + _PAGE_PSE.
320                                  */
321                                 pgprot_t init_prot =
322                                         __pgprot(PTE_IDENT_ATTR |
323                                                  _PAGE_PSE);
324 
325                                 pfn &= PMD_MASK >> PAGE_SHIFT;
326                                 addr2 = (pfn + PTRS_PER_PTE-1) * PAGE_SIZE +
327                                         PAGE_OFFSET + PAGE_SIZE-1;
328 
329                                 if (is_kernel_text(addr) ||
330                                     is_kernel_text(addr2))
331                                         prot = PAGE_KERNEL_LARGE_EXEC;
332 
333                                 pages_2m++;
334                                 if (mapping_iter == 1)
335                                         set_pmd(pmd, pfn_pmd(pfn, init_prot));
336                                 else
337                                         set_pmd(pmd, pfn_pmd(pfn, prot));
338 
339                                 pfn += PTRS_PER_PTE;
340                                 continue;
341                         }
342                         pte = one_page_table_init(pmd);
343 
344                         pte_ofs = pte_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
345                         pte += pte_ofs;
346                         for (; pte_ofs < PTRS_PER_PTE && pfn < end_pfn;
347                              pte++, pfn++, pte_ofs++, addr += PAGE_SIZE) {
348                                 pgprot_t prot = PAGE_KERNEL;
349                                 /*
350                                  * first pass will use the same initial
351                                  * identity mapping attribute.
352                                  */
353                                 pgprot_t init_prot = __pgprot(PTE_IDENT_ATTR);
354 
355                                 if (is_kernel_text(addr))
356                                         prot = PAGE_KERNEL_EXEC;
357 
358                                 pages_4k++;
359                                 if (mapping_iter == 1) {
360                                         set_pte(pte, pfn_pte(pfn, init_prot));
361                                         last_map_addr = (pfn << PAGE_SHIFT) + PAGE_SIZE;
362                                 } else
363                                         set_pte(pte, pfn_pte(pfn, prot));
364                         }
365                 }
366         }
367         if (mapping_iter == 1) {
368                 /*
369                  * update direct mapping page count only in the first
370                  * iteration.
371                  */
372                 update_page_count(PG_LEVEL_2M, pages_2m);
373                 update_page_count(PG_LEVEL_4K, pages_4k);
374 
375                 /*
376                  * local global flush tlb, which will flush the previous
377                  * mappings present in both small and large page TLB's.
378                  */
379                 __flush_tlb_all();
380 
381                 /*
382                  * Second iteration will set the actual desired PTE attributes.
383                  */
384                 mapping_iter = 2;
385                 goto repeat;
386         }
387         return last_map_addr;
388 }
389 
390 pte_t *kmap_pte;
391 pgprot_t kmap_prot;
392 
393 static inline pte_t *kmap_get_fixmap_pte(unsigned long vaddr)
394 {
395         return pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr),
396                         vaddr), vaddr), vaddr);
397 }
398 
399 static void __init kmap_init(void)
400 {
401         unsigned long kmap_vstart;
402 
403         /*
404          * Cache the first kmap pte:
405          */
406         kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
407         kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
408 
409         kmap_prot = PAGE_KERNEL;
410 }
411 
412 #ifdef CONFIG_HIGHMEM
413 static void __init permanent_kmaps_init(pgd_t *pgd_base)
414 {
415         unsigned long vaddr;
416         pgd_t *pgd;
417         pud_t *pud;
418         pmd_t *pmd;
419         pte_t *pte;
420 
421         vaddr = PKMAP_BASE;
422         page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
423 
424         pgd = swapper_pg_dir + pgd_index(vaddr);
425         pud = pud_offset(pgd, vaddr);
426         pmd = pmd_offset(pud, vaddr);
427         pte = pte_offset_kernel(pmd, vaddr);
428         pkmap_page_table = pte;
429 }
430 
431 void __init add_highpages_with_active_regions(int nid,
432                          unsigned long start_pfn, unsigned long end_pfn)
433 {
434         phys_addr_t start, end;
435         u64 i;
436 
437         for_each_free_mem_range(i, nid, &start, &end, NULL) {
438                 unsigned long pfn = clamp_t(unsigned long, PFN_UP(start),
439                                             start_pfn, end_pfn);
440                 unsigned long e_pfn = clamp_t(unsigned long, PFN_DOWN(end),
441                                               start_pfn, end_pfn);
442                 for ( ; pfn < e_pfn; pfn++)
443                         if (pfn_valid(pfn))
444                                 free_highmem_page(pfn_to_page(pfn));
445         }
446 }
447 #else
448 static inline void permanent_kmaps_init(pgd_t *pgd_base)
449 {
450 }
451 #endif /* CONFIG_HIGHMEM */
452 
453 void __init native_pagetable_init(void)
454 {
455         unsigned long pfn, va;
456         pgd_t *pgd, *base = swapper_pg_dir;
457         pud_t *pud;
458         pmd_t *pmd;
459         pte_t *pte;
460 
461         /*
462          * Remove any mappings which extend past the end of physical
463          * memory from the boot time page table.
464          * In virtual address space, we should have at least two pages
465          * from VMALLOC_END to pkmap or fixmap according to VMALLOC_END
466          * definition. And max_low_pfn is set to VMALLOC_END physical
467          * address. If initial memory mapping is doing right job, we
468          * should have pte used near max_low_pfn or one pmd is not present.
469          */
470         for (pfn = max_low_pfn; pfn < 1<<(32-PAGE_SHIFT); pfn++) {
471                 va = PAGE_OFFSET + (pfn<<PAGE_SHIFT);
472                 pgd = base + pgd_index(va);
473                 if (!pgd_present(*pgd))
474                         break;
475 
476                 pud = pud_offset(pgd, va);
477                 pmd = pmd_offset(pud, va);
478                 if (!pmd_present(*pmd))
479                         break;
480 
481                 /* should not be large page here */
482                 if (pmd_large(*pmd)) {
483                         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",
484                                 pfn, pmd, __pa(pmd));
485                         BUG_ON(1);
486                 }
487 
488                 pte = pte_offset_kernel(pmd, va);
489                 if (!pte_present(*pte))
490                         break;
491 
492                 printk(KERN_DEBUG "clearing pte for ram above max_low_pfn: pfn: %lx pmd: %p pmd phys: %lx pte: %p pte phys: %lx\n",
493                                 pfn, pmd, __pa(pmd), pte, __pa(pte));
494                 pte_clear(NULL, va, pte);
495         }
496         paravirt_alloc_pmd(&init_mm, __pa(base) >> PAGE_SHIFT);
497         paging_init();
498 }
499 
500 /*
501  * Build a proper pagetable for the kernel mappings.  Up until this
502  * point, we've been running on some set of pagetables constructed by
503  * the boot process.
504  *
505  * If we're booting on native hardware, this will be a pagetable
506  * constructed in arch/x86/kernel/head_32.S.  The root of the
507  * pagetable will be swapper_pg_dir.
508  *
509  * If we're booting paravirtualized under a hypervisor, then there are
510  * more options: we may already be running PAE, and the pagetable may
511  * or may not be based in swapper_pg_dir.  In any case,
512  * paravirt_pagetable_init() will set up swapper_pg_dir
513  * appropriately for the rest of the initialization to work.
514  *
515  * In general, pagetable_init() assumes that the pagetable may already
516  * be partially populated, and so it avoids stomping on any existing
517  * mappings.
518  */
519 void __init early_ioremap_page_table_range_init(void)
520 {
521         pgd_t *pgd_base = swapper_pg_dir;
522         unsigned long vaddr, end;
523 
524         /*
525          * Fixed mappings, only the page table structure has to be
526          * created - mappings will be set by set_fixmap():
527          */
528         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
529         end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
530         page_table_range_init(vaddr, end, pgd_base);
531         early_ioremap_reset();
532 }
533 
534 static void __init pagetable_init(void)
535 {
536         pgd_t *pgd_base = swapper_pg_dir;
537 
538         permanent_kmaps_init(pgd_base);
539 }
540 
541 pteval_t __supported_pte_mask __read_mostly = ~(_PAGE_NX | _PAGE_GLOBAL | _PAGE_IOMAP);
542 EXPORT_SYMBOL_GPL(__supported_pte_mask);
543 
544 /* user-defined highmem size */
545 static unsigned int highmem_pages = -1;
546 
547 /*
548  * highmem=size forces highmem to be exactly 'size' bytes.
549  * This works even on boxes that have no highmem otherwise.
550  * This also works to reduce highmem size on bigger boxes.
551  */
552 static int __init parse_highmem(char *arg)
553 {
554         if (!arg)
555                 return -EINVAL;
556 
557         highmem_pages = memparse(arg, &arg) >> PAGE_SHIFT;
558         return 0;
559 }
560 early_param("highmem", parse_highmem);
561 
562 #define MSG_HIGHMEM_TOO_BIG \
563         "highmem size (%luMB) is bigger than pages available (%luMB)!\n"
564 
565 #define MSG_LOWMEM_TOO_SMALL \
566         "highmem size (%luMB) results in <64MB lowmem, ignoring it!\n"
567 /*
568  * All of RAM fits into lowmem - but if user wants highmem
569  * artificially via the highmem=x boot parameter then create
570  * it:
571  */
572 static void __init lowmem_pfn_init(void)
573 {
574         /* max_low_pfn is 0, we already have early_res support */
575         max_low_pfn = max_pfn;
576 
577         if (highmem_pages == -1)
578                 highmem_pages = 0;
579 #ifdef CONFIG_HIGHMEM
580         if (highmem_pages >= max_pfn) {
581                 printk(KERN_ERR MSG_HIGHMEM_TOO_BIG,
582                         pages_to_mb(highmem_pages), pages_to_mb(max_pfn));
583                 highmem_pages = 0;
584         }
585         if (highmem_pages) {
586                 if (max_low_pfn - highmem_pages < 64*1024*1024/PAGE_SIZE) {
587                         printk(KERN_ERR MSG_LOWMEM_TOO_SMALL,
588                                 pages_to_mb(highmem_pages));
589                         highmem_pages = 0;
590                 }
591                 max_low_pfn -= highmem_pages;
592         }
593 #else
594         if (highmem_pages)
595                 printk(KERN_ERR "ignoring highmem size on non-highmem kernel!\n");
596 #endif
597 }
598 
599 #define MSG_HIGHMEM_TOO_SMALL \
600         "only %luMB highmem pages available, ignoring highmem size of %luMB!\n"
601 
602 #define MSG_HIGHMEM_TRIMMED \
603         "Warning: only 4GB will be used. Use a HIGHMEM64G enabled kernel!\n"
604 /*
605  * We have more RAM than fits into lowmem - we try to put it into
606  * highmem, also taking the highmem=x boot parameter into account:
607  */
608 static void __init highmem_pfn_init(void)
609 {
610         max_low_pfn = MAXMEM_PFN;
611 
612         if (highmem_pages == -1)
613                 highmem_pages = max_pfn - MAXMEM_PFN;
614 
615         if (highmem_pages + MAXMEM_PFN < max_pfn)
616                 max_pfn = MAXMEM_PFN + highmem_pages;
617 
618         if (highmem_pages + MAXMEM_PFN > max_pfn) {
619                 printk(KERN_WARNING MSG_HIGHMEM_TOO_SMALL,
620                         pages_to_mb(max_pfn - MAXMEM_PFN),
621                         pages_to_mb(highmem_pages));
622                 highmem_pages = 0;
623         }
624 #ifndef CONFIG_HIGHMEM
625         /* Maximum memory usable is what is directly addressable */
626         printk(KERN_WARNING "Warning only %ldMB will be used.\n", MAXMEM>>20);
627         if (max_pfn > MAX_NONPAE_PFN)
628                 printk(KERN_WARNING "Use a HIGHMEM64G enabled kernel.\n");
629         else
630                 printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
631         max_pfn = MAXMEM_PFN;
632 #else /* !CONFIG_HIGHMEM */
633 #ifndef CONFIG_HIGHMEM64G
634         if (max_pfn > MAX_NONPAE_PFN) {
635                 max_pfn = MAX_NONPAE_PFN;
636                 printk(KERN_WARNING MSG_HIGHMEM_TRIMMED);
637         }
638 #endif /* !CONFIG_HIGHMEM64G */
639 #endif /* !CONFIG_HIGHMEM */
640 }
641 
642 /*
643  * Determine low and high memory ranges:
644  */
645 void __init find_low_pfn_range(void)
646 {
647         /* it could update max_pfn */
648 
649         if (max_pfn <= MAXMEM_PFN)
650                 lowmem_pfn_init();
651         else
652                 highmem_pfn_init();
653 }
654 
655 #ifndef CONFIG_NEED_MULTIPLE_NODES
656 void __init initmem_init(void)
657 {
658 #ifdef CONFIG_HIGHMEM
659         highstart_pfn = highend_pfn = max_pfn;
660         if (max_pfn > max_low_pfn)
661                 highstart_pfn = max_low_pfn;
662         printk(KERN_NOTICE "%ldMB HIGHMEM available.\n",
663                 pages_to_mb(highend_pfn - highstart_pfn));
664         high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
665 #else
666         high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
667 #endif
668 
669         memblock_set_node(0, (phys_addr_t)ULLONG_MAX, &memblock.memory, 0);
670         sparse_memory_present_with_active_regions(0);
671 
672 #ifdef CONFIG_FLATMEM
673         max_mapnr = IS_ENABLED(CONFIG_HIGHMEM) ? highend_pfn : max_low_pfn;
674 #endif
675         __vmalloc_start_set = true;
676 
677         printk(KERN_NOTICE "%ldMB LOWMEM available.\n",
678                         pages_to_mb(max_low_pfn));
679 
680         setup_bootmem_allocator();
681 }
682 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
683 
684 void __init setup_bootmem_allocator(void)
685 {
686         printk(KERN_INFO "  mapped low ram: 0 - %08lx\n",
687                  max_pfn_mapped<<PAGE_SHIFT);
688         printk(KERN_INFO "  low ram: 0 - %08lx\n", max_low_pfn<<PAGE_SHIFT);
689 }
690 
691 /*
692  * paging_init() sets up the page tables - note that the first 8MB are
693  * already mapped by head.S.
694  *
695  * This routines also unmaps the page at virtual kernel address 0, so
696  * that we can trap those pesky NULL-reference errors in the kernel.
697  */
698 void __init paging_init(void)
699 {
700         pagetable_init();
701 
702         __flush_tlb_all();
703 
704         kmap_init();
705 
706         /*
707          * NOTE: at this point the bootmem allocator is fully available.
708          */
709         olpc_dt_build_devicetree();
710         sparse_memory_present_with_active_regions(MAX_NUMNODES);
711         sparse_init();
712         zone_sizes_init();
713 }
714 
715 /*
716  * Test if the WP bit works in supervisor mode. It isn't supported on 386's
717  * and also on some strange 486's. All 586+'s are OK. This used to involve
718  * black magic jumps to work around some nasty CPU bugs, but fortunately the
719  * switch to using exceptions got rid of all that.
720  */
721 static void __init test_wp_bit(void)
722 {
723         printk(KERN_INFO
724   "Checking if this processor honours the WP bit even in supervisor mode...");
725 
726         /* Any page-aligned address will do, the test is non-destructive */
727         __set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_KERNEL_RO);
728         boot_cpu_data.wp_works_ok = do_test_wp_bit();
729         clear_fixmap(FIX_WP_TEST);
730 
731         if (!boot_cpu_data.wp_works_ok) {
732                 printk(KERN_CONT "No.\n");
733                 panic("Linux doesn't support CPUs with broken WP.");
734         } else {
735                 printk(KERN_CONT "Ok.\n");
736         }
737 }
738 
739 void __init mem_init(void)
740 {
741         pci_iommu_alloc();
742 
743 #ifdef CONFIG_FLATMEM
744         BUG_ON(!mem_map);
745 #endif
746         /*
747          * With CONFIG_DEBUG_PAGEALLOC initialization of highmem pages has to
748          * be done before free_all_bootmem(). Memblock use free low memory for
749          * temporary data (see find_range_array()) and for this purpose can use
750          * pages that was already passed to the buddy allocator, hence marked as
751          * not accessible in the page tables when compiled with
752          * CONFIG_DEBUG_PAGEALLOC. Otherwise order of initialization is not
753          * important here.
754          */
755         set_highmem_pages_init();
756 
757         /* this will put all low memory onto the freelists */
758         free_all_bootmem();
759 
760         after_bootmem = 1;
761 
762         mem_init_print_info(NULL);
763         printk(KERN_INFO "virtual kernel memory layout:\n"
764                 "    fixmap  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
765 #ifdef CONFIG_HIGHMEM
766                 "    pkmap   : 0x%08lx - 0x%08lx   (%4ld kB)\n"
767 #endif
768                 "    vmalloc : 0x%08lx - 0x%08lx   (%4ld MB)\n"
769                 "    lowmem  : 0x%08lx - 0x%08lx   (%4ld MB)\n"
770                 "      .init : 0x%08lx - 0x%08lx   (%4ld kB)\n"
771                 "      .data : 0x%08lx - 0x%08lx   (%4ld kB)\n"
772                 "      .text : 0x%08lx - 0x%08lx   (%4ld kB)\n",
773                 FIXADDR_START, FIXADDR_TOP,
774                 (FIXADDR_TOP - FIXADDR_START) >> 10,
775 
776 #ifdef CONFIG_HIGHMEM
777                 PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE,
778                 (LAST_PKMAP*PAGE_SIZE) >> 10,
779 #endif
780 
781                 VMALLOC_START, VMALLOC_END,
782                 (VMALLOC_END - VMALLOC_START) >> 20,
783 
784                 (unsigned long)__va(0), (unsigned long)high_memory,
785                 ((unsigned long)high_memory - (unsigned long)__va(0)) >> 20,
786 
787                 (unsigned long)&__init_begin, (unsigned long)&__init_end,
788                 ((unsigned long)&__init_end -
789                  (unsigned long)&__init_begin) >> 10,
790 
791                 (unsigned long)&_etext, (unsigned long)&_edata,
792                 ((unsigned long)&_edata - (unsigned long)&_etext) >> 10,
793 
794                 (unsigned long)&_text, (unsigned long)&_etext,
795                 ((unsigned long)&_etext - (unsigned long)&_text) >> 10);
796 
797         /*
798          * Check boundaries twice: Some fundamental inconsistencies can
799          * be detected at build time already.
800          */
801 #define __FIXADDR_TOP (-PAGE_SIZE)
802 #ifdef CONFIG_HIGHMEM
803         BUILD_BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE  > FIXADDR_START);
804         BUILD_BUG_ON(VMALLOC_END                        > PKMAP_BASE);
805 #endif
806 #define high_memory (-128UL << 20)
807         BUILD_BUG_ON(VMALLOC_START                      >= VMALLOC_END);
808 #undef high_memory
809 #undef __FIXADDR_TOP
810 #ifdef CONFIG_RANDOMIZE_BASE
811         BUILD_BUG_ON(CONFIG_RANDOMIZE_BASE_MAX_OFFSET > KERNEL_IMAGE_SIZE);
812 #endif
813 
814 #ifdef CONFIG_HIGHMEM
815         BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE        > FIXADDR_START);
816         BUG_ON(VMALLOC_END                              > PKMAP_BASE);
817 #endif
818         BUG_ON(VMALLOC_START                            >= VMALLOC_END);
819         BUG_ON((unsigned long)high_memory               > VMALLOC_START);
820 
821         if (boot_cpu_data.wp_works_ok < 0)
822                 test_wp_bit();
823 }
824 
825 #ifdef CONFIG_MEMORY_HOTPLUG
826 int arch_add_memory(int nid, u64 start, u64 size)
827 {
828         struct pglist_data *pgdata = NODE_DATA(nid);
829         struct zone *zone = pgdata->node_zones + ZONE_HIGHMEM;
830         unsigned long start_pfn = start >> PAGE_SHIFT;
831         unsigned long nr_pages = size >> PAGE_SHIFT;
832 
833         return __add_pages(nid, zone, start_pfn, nr_pages);
834 }
835 
836 #ifdef CONFIG_MEMORY_HOTREMOVE
837 int arch_remove_memory(u64 start, u64 size)
838 {
839         unsigned long start_pfn = start >> PAGE_SHIFT;
840         unsigned long nr_pages = size >> PAGE_SHIFT;
841         struct zone *zone;
842 
843         zone = page_zone(pfn_to_page(start_pfn));
844         return __remove_pages(zone, start_pfn, nr_pages);
845 }
846 #endif
847 #endif
848 
849 /*
850  * This function cannot be __init, since exceptions don't work in that
851  * section.  Put this after the callers, so that it cannot be inlined.
852  */
853 static noinline int do_test_wp_bit(void)
854 {
855         char tmp_reg;
856         int flag;
857 
858         __asm__ __volatile__(
859                 "       movb %0, %1     \n"
860                 "1:     movb %1, %0     \n"
861                 "       xorl %2, %2     \n"
862                 "2:                     \n"
863                 _ASM_EXTABLE(1b,2b)
864                 :"=m" (*(char *)fix_to_virt(FIX_WP_TEST)),
865                  "=q" (tmp_reg),
866                  "=r" (flag)
867                 :"2" (1)
868                 :"memory");
869 
870         return flag;
871 }
872 
873 #ifdef CONFIG_DEBUG_RODATA
874 const int rodata_test_data = 0xC3;
875 EXPORT_SYMBOL_GPL(rodata_test_data);
876 
877 int kernel_set_to_readonly __read_mostly;
878 
879 void set_kernel_text_rw(void)
880 {
881         unsigned long start = PFN_ALIGN(_text);
882         unsigned long size = PFN_ALIGN(_etext) - start;
883 
884         if (!kernel_set_to_readonly)
885                 return;
886 
887         pr_debug("Set kernel text: %lx - %lx for read write\n",
888                  start, start+size);
889 
890         set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
891 }
892 
893 void set_kernel_text_ro(void)
894 {
895         unsigned long start = PFN_ALIGN(_text);
896         unsigned long size = PFN_ALIGN(_etext) - start;
897 
898         if (!kernel_set_to_readonly)
899                 return;
900 
901         pr_debug("Set kernel text: %lx - %lx for read only\n",
902                  start, start+size);
903 
904         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
905 }
906 
907 static void mark_nxdata_nx(void)
908 {
909         /*
910          * When this called, init has already been executed and released,
911          * so everything past _etext should be NX.
912          */
913         unsigned long start = PFN_ALIGN(_etext);
914         /*
915          * This comes from is_kernel_text upper limit. Also HPAGE where used:
916          */
917         unsigned long size = (((unsigned long)__init_end + HPAGE_SIZE) & HPAGE_MASK) - start;
918 
919         if (__supported_pte_mask & _PAGE_NX)
920                 printk(KERN_INFO "NX-protecting the kernel data: %luk\n", size >> 10);
921         set_pages_nx(virt_to_page(start), size >> PAGE_SHIFT);
922 }
923 
924 void mark_rodata_ro(void)
925 {
926         unsigned long start = PFN_ALIGN(_text);
927         unsigned long size = PFN_ALIGN(_etext) - start;
928 
929         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
930         printk(KERN_INFO "Write protecting the kernel text: %luk\n",
931                 size >> 10);
932 
933         kernel_set_to_readonly = 1;
934 
935 #ifdef CONFIG_CPA_DEBUG
936         printk(KERN_INFO "Testing CPA: Reverting %lx-%lx\n",
937                 start, start+size);
938         set_pages_rw(virt_to_page(start), size>>PAGE_SHIFT);
939 
940         printk(KERN_INFO "Testing CPA: write protecting again\n");
941         set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
942 #endif
943 
944         start += size;
945         size = (unsigned long)__end_rodata - start;
946         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
947         printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
948                 size >> 10);
949         rodata_test();
950 
951 #ifdef CONFIG_CPA_DEBUG
952         printk(KERN_INFO "Testing CPA: undo %lx-%lx\n", start, start + size);
953         set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
954 
955         printk(KERN_INFO "Testing CPA: write protecting again\n");
956         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
957 #endif
958         mark_nxdata_nx();
959 }
960 #endif
961 
962 

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