xref: /openbmc/linux/arch/x86/mm/init_32.c (revision 4da722ca)
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/api.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/set_memory.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 bool __read_mostly __vmalloc_start_set = false;
60 
61 /*
62  * Creates a middle page table and puts a pointer to it in the
63  * given global directory entry. This only returns the gd entry
64  * in non-PAE compilation mode, since the middle layer is folded.
65  */
66 static pmd_t * __init one_md_table_init(pgd_t *pgd)
67 {
68 	p4d_t *p4d;
69 	pud_t *pud;
70 	pmd_t *pmd_table;
71 
72 #ifdef CONFIG_X86_PAE
73 	if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
74 		pmd_table = (pmd_t *)alloc_low_page();
75 		paravirt_alloc_pmd(&init_mm, __pa(pmd_table) >> PAGE_SHIFT);
76 		set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
77 		p4d = p4d_offset(pgd, 0);
78 		pud = pud_offset(p4d, 0);
79 		BUG_ON(pmd_table != pmd_offset(pud, 0));
80 
81 		return pmd_table;
82 	}
83 #endif
84 	p4d = p4d_offset(pgd, 0);
85 	pud = pud_offset(p4d, 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 (!boot_cpu_has(X86_FEATURE_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 
392 static inline pte_t *kmap_get_fixmap_pte(unsigned long vaddr)
393 {
394 	pgd_t *pgd = pgd_offset_k(vaddr);
395 	p4d_t *p4d = p4d_offset(pgd, vaddr);
396 	pud_t *pud = pud_offset(p4d, vaddr);
397 	pmd_t *pmd = pmd_offset(pud, vaddr);
398 	return pte_offset_kernel(pmd, vaddr);
399 }
400 
401 static void __init kmap_init(void)
402 {
403 	unsigned long kmap_vstart;
404 
405 	/*
406 	 * Cache the first kmap pte:
407 	 */
408 	kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
409 	kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
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 	p4d_t *p4d;
418 	pud_t *pud;
419 	pmd_t *pmd;
420 	pte_t *pte;
421 
422 	vaddr = PKMAP_BASE;
423 	page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
424 
425 	pgd = swapper_pg_dir + pgd_index(vaddr);
426 	p4d = p4d_offset(pgd, vaddr);
427 	pud = pud_offset(p4d, vaddr);
428 	pmd = pmd_offset(pud, vaddr);
429 	pte = pte_offset_kernel(pmd, vaddr);
430 	pkmap_page_table = pte;
431 }
432 
433 void __init add_highpages_with_active_regions(int nid,
434 			 unsigned long start_pfn, unsigned long end_pfn)
435 {
436 	phys_addr_t start, end;
437 	u64 i;
438 
439 	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &start, &end, NULL) {
440 		unsigned long pfn = clamp_t(unsigned long, PFN_UP(start),
441 					    start_pfn, end_pfn);
442 		unsigned long e_pfn = clamp_t(unsigned long, PFN_DOWN(end),
443 					      start_pfn, end_pfn);
444 		for ( ; pfn < e_pfn; pfn++)
445 			if (pfn_valid(pfn))
446 				free_highmem_page(pfn_to_page(pfn));
447 	}
448 }
449 #else
450 static inline void permanent_kmaps_init(pgd_t *pgd_base)
451 {
452 }
453 #endif /* CONFIG_HIGHMEM */
454 
455 void __init native_pagetable_init(void)
456 {
457 	unsigned long pfn, va;
458 	pgd_t *pgd, *base = swapper_pg_dir;
459 	p4d_t *p4d;
460 	pud_t *pud;
461 	pmd_t *pmd;
462 	pte_t *pte;
463 
464 	/*
465 	 * Remove any mappings which extend past the end of physical
466 	 * memory from the boot time page table.
467 	 * In virtual address space, we should have at least two pages
468 	 * from VMALLOC_END to pkmap or fixmap according to VMALLOC_END
469 	 * definition. And max_low_pfn is set to VMALLOC_END physical
470 	 * address. If initial memory mapping is doing right job, we
471 	 * should have pte used near max_low_pfn or one pmd is not present.
472 	 */
473 	for (pfn = max_low_pfn; pfn < 1<<(32-PAGE_SHIFT); pfn++) {
474 		va = PAGE_OFFSET + (pfn<<PAGE_SHIFT);
475 		pgd = base + pgd_index(va);
476 		if (!pgd_present(*pgd))
477 			break;
478 
479 		p4d = p4d_offset(pgd, va);
480 		pud = pud_offset(p4d, va);
481 		pmd = pmd_offset(pud, va);
482 		if (!pmd_present(*pmd))
483 			break;
484 
485 		/* should not be large page here */
486 		if (pmd_large(*pmd)) {
487 			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",
488 				pfn, pmd, __pa(pmd));
489 			BUG_ON(1);
490 		}
491 
492 		pte = pte_offset_kernel(pmd, va);
493 		if (!pte_present(*pte))
494 			break;
495 
496 		printk(KERN_DEBUG "clearing pte for ram above max_low_pfn: pfn: %lx pmd: %p pmd phys: %lx pte: %p pte phys: %lx\n",
497 				pfn, pmd, __pa(pmd), pte, __pa(pte));
498 		pte_clear(NULL, va, pte);
499 	}
500 	paravirt_alloc_pmd(&init_mm, __pa(base) >> PAGE_SHIFT);
501 	paging_init();
502 }
503 
504 /*
505  * Build a proper pagetable for the kernel mappings.  Up until this
506  * point, we've been running on some set of pagetables constructed by
507  * the boot process.
508  *
509  * If we're booting on native hardware, this will be a pagetable
510  * constructed in arch/x86/kernel/head_32.S.  The root of the
511  * pagetable will be swapper_pg_dir.
512  *
513  * If we're booting paravirtualized under a hypervisor, then there are
514  * more options: we may already be running PAE, and the pagetable may
515  * or may not be based in swapper_pg_dir.  In any case,
516  * paravirt_pagetable_init() will set up swapper_pg_dir
517  * appropriately for the rest of the initialization to work.
518  *
519  * In general, pagetable_init() assumes that the pagetable may already
520  * be partially populated, and so it avoids stomping on any existing
521  * mappings.
522  */
523 void __init early_ioremap_page_table_range_init(void)
524 {
525 	pgd_t *pgd_base = swapper_pg_dir;
526 	unsigned long vaddr, end;
527 
528 	/*
529 	 * Fixed mappings, only the page table structure has to be
530 	 * created - mappings will be set by set_fixmap():
531 	 */
532 	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
533 	end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
534 	page_table_range_init(vaddr, end, pgd_base);
535 	early_ioremap_reset();
536 }
537 
538 static void __init pagetable_init(void)
539 {
540 	pgd_t *pgd_base = swapper_pg_dir;
541 
542 	permanent_kmaps_init(pgd_base);
543 }
544 
545 pteval_t __supported_pte_mask __read_mostly = ~(_PAGE_NX | _PAGE_GLOBAL);
546 EXPORT_SYMBOL_GPL(__supported_pte_mask);
547 
548 /* user-defined highmem size */
549 static unsigned int highmem_pages = -1;
550 
551 /*
552  * highmem=size forces highmem to be exactly 'size' bytes.
553  * This works even on boxes that have no highmem otherwise.
554  * This also works to reduce highmem size on bigger boxes.
555  */
556 static int __init parse_highmem(char *arg)
557 {
558 	if (!arg)
559 		return -EINVAL;
560 
561 	highmem_pages = memparse(arg, &arg) >> PAGE_SHIFT;
562 	return 0;
563 }
564 early_param("highmem", parse_highmem);
565 
566 #define MSG_HIGHMEM_TOO_BIG \
567 	"highmem size (%luMB) is bigger than pages available (%luMB)!\n"
568 
569 #define MSG_LOWMEM_TOO_SMALL \
570 	"highmem size (%luMB) results in <64MB lowmem, ignoring it!\n"
571 /*
572  * All of RAM fits into lowmem - but if user wants highmem
573  * artificially via the highmem=x boot parameter then create
574  * it:
575  */
576 static void __init lowmem_pfn_init(void)
577 {
578 	/* max_low_pfn is 0, we already have early_res support */
579 	max_low_pfn = max_pfn;
580 
581 	if (highmem_pages == -1)
582 		highmem_pages = 0;
583 #ifdef CONFIG_HIGHMEM
584 	if (highmem_pages >= max_pfn) {
585 		printk(KERN_ERR MSG_HIGHMEM_TOO_BIG,
586 			pages_to_mb(highmem_pages), pages_to_mb(max_pfn));
587 		highmem_pages = 0;
588 	}
589 	if (highmem_pages) {
590 		if (max_low_pfn - highmem_pages < 64*1024*1024/PAGE_SIZE) {
591 			printk(KERN_ERR MSG_LOWMEM_TOO_SMALL,
592 				pages_to_mb(highmem_pages));
593 			highmem_pages = 0;
594 		}
595 		max_low_pfn -= highmem_pages;
596 	}
597 #else
598 	if (highmem_pages)
599 		printk(KERN_ERR "ignoring highmem size on non-highmem kernel!\n");
600 #endif
601 }
602 
603 #define MSG_HIGHMEM_TOO_SMALL \
604 	"only %luMB highmem pages available, ignoring highmem size of %luMB!\n"
605 
606 #define MSG_HIGHMEM_TRIMMED \
607 	"Warning: only 4GB will be used. Use a HIGHMEM64G enabled kernel!\n"
608 /*
609  * We have more RAM than fits into lowmem - we try to put it into
610  * highmem, also taking the highmem=x boot parameter into account:
611  */
612 static void __init highmem_pfn_init(void)
613 {
614 	max_low_pfn = MAXMEM_PFN;
615 
616 	if (highmem_pages == -1)
617 		highmem_pages = max_pfn - MAXMEM_PFN;
618 
619 	if (highmem_pages + MAXMEM_PFN < max_pfn)
620 		max_pfn = MAXMEM_PFN + highmem_pages;
621 
622 	if (highmem_pages + MAXMEM_PFN > max_pfn) {
623 		printk(KERN_WARNING MSG_HIGHMEM_TOO_SMALL,
624 			pages_to_mb(max_pfn - MAXMEM_PFN),
625 			pages_to_mb(highmem_pages));
626 		highmem_pages = 0;
627 	}
628 #ifndef CONFIG_HIGHMEM
629 	/* Maximum memory usable is what is directly addressable */
630 	printk(KERN_WARNING "Warning only %ldMB will be used.\n", MAXMEM>>20);
631 	if (max_pfn > MAX_NONPAE_PFN)
632 		printk(KERN_WARNING "Use a HIGHMEM64G enabled kernel.\n");
633 	else
634 		printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
635 	max_pfn = MAXMEM_PFN;
636 #else /* !CONFIG_HIGHMEM */
637 #ifndef CONFIG_HIGHMEM64G
638 	if (max_pfn > MAX_NONPAE_PFN) {
639 		max_pfn = MAX_NONPAE_PFN;
640 		printk(KERN_WARNING MSG_HIGHMEM_TRIMMED);
641 	}
642 #endif /* !CONFIG_HIGHMEM64G */
643 #endif /* !CONFIG_HIGHMEM */
644 }
645 
646 /*
647  * Determine low and high memory ranges:
648  */
649 void __init find_low_pfn_range(void)
650 {
651 	/* it could update max_pfn */
652 
653 	if (max_pfn <= MAXMEM_PFN)
654 		lowmem_pfn_init();
655 	else
656 		highmem_pfn_init();
657 }
658 
659 #ifndef CONFIG_NEED_MULTIPLE_NODES
660 void __init initmem_init(void)
661 {
662 #ifdef CONFIG_HIGHMEM
663 	highstart_pfn = highend_pfn = max_pfn;
664 	if (max_pfn > max_low_pfn)
665 		highstart_pfn = max_low_pfn;
666 	printk(KERN_NOTICE "%ldMB HIGHMEM available.\n",
667 		pages_to_mb(highend_pfn - highstart_pfn));
668 	high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
669 #else
670 	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
671 #endif
672 
673 	memblock_set_node(0, (phys_addr_t)ULLONG_MAX, &memblock.memory, 0);
674 	sparse_memory_present_with_active_regions(0);
675 
676 #ifdef CONFIG_FLATMEM
677 	max_mapnr = IS_ENABLED(CONFIG_HIGHMEM) ? highend_pfn : max_low_pfn;
678 #endif
679 	__vmalloc_start_set = true;
680 
681 	printk(KERN_NOTICE "%ldMB LOWMEM available.\n",
682 			pages_to_mb(max_low_pfn));
683 
684 	setup_bootmem_allocator();
685 }
686 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
687 
688 void __init setup_bootmem_allocator(void)
689 {
690 	printk(KERN_INFO "  mapped low ram: 0 - %08lx\n",
691 		 max_pfn_mapped<<PAGE_SHIFT);
692 	printk(KERN_INFO "  low ram: 0 - %08lx\n", max_low_pfn<<PAGE_SHIFT);
693 }
694 
695 /*
696  * paging_init() sets up the page tables - note that the first 8MB are
697  * already mapped by head.S.
698  *
699  * This routines also unmaps the page at virtual kernel address 0, so
700  * that we can trap those pesky NULL-reference errors in the kernel.
701  */
702 void __init paging_init(void)
703 {
704 	pagetable_init();
705 
706 	__flush_tlb_all();
707 
708 	kmap_init();
709 
710 	/*
711 	 * NOTE: at this point the bootmem allocator is fully available.
712 	 */
713 	olpc_dt_build_devicetree();
714 	sparse_memory_present_with_active_regions(MAX_NUMNODES);
715 	sparse_init();
716 	zone_sizes_init();
717 }
718 
719 /*
720  * Test if the WP bit works in supervisor mode. It isn't supported on 386's
721  * and also on some strange 486's. All 586+'s are OK. This used to involve
722  * black magic jumps to work around some nasty CPU bugs, but fortunately the
723  * switch to using exceptions got rid of all that.
724  */
725 static void __init test_wp_bit(void)
726 {
727 	char z = 0;
728 
729 	printk(KERN_INFO "Checking if this processor honours the WP bit even in supervisor mode...");
730 
731 	__set_fixmap(FIX_WP_TEST, __pa_symbol(empty_zero_page), PAGE_KERNEL_RO);
732 
733 	if (probe_kernel_write((char *)fix_to_virt(FIX_WP_TEST), &z, 1)) {
734 		clear_fixmap(FIX_WP_TEST);
735 		printk(KERN_CONT "Ok.\n");
736 		return;
737 	}
738 
739 	printk(KERN_CONT "No.\n");
740 	panic("Linux doesn't support CPUs with broken WP.");
741 }
742 
743 void __init mem_init(void)
744 {
745 	pci_iommu_alloc();
746 
747 #ifdef CONFIG_FLATMEM
748 	BUG_ON(!mem_map);
749 #endif
750 	/*
751 	 * With CONFIG_DEBUG_PAGEALLOC initialization of highmem pages has to
752 	 * be done before free_all_bootmem(). Memblock use free low memory for
753 	 * temporary data (see find_range_array()) and for this purpose can use
754 	 * pages that was already passed to the buddy allocator, hence marked as
755 	 * not accessible in the page tables when compiled with
756 	 * CONFIG_DEBUG_PAGEALLOC. Otherwise order of initialization is not
757 	 * important here.
758 	 */
759 	set_highmem_pages_init();
760 
761 	/* this will put all low memory onto the freelists */
762 	free_all_bootmem();
763 
764 	after_bootmem = 1;
765 
766 	mem_init_print_info(NULL);
767 	printk(KERN_INFO "virtual kernel memory layout:\n"
768 		"    fixmap  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
769 #ifdef CONFIG_HIGHMEM
770 		"    pkmap   : 0x%08lx - 0x%08lx   (%4ld kB)\n"
771 #endif
772 		"    vmalloc : 0x%08lx - 0x%08lx   (%4ld MB)\n"
773 		"    lowmem  : 0x%08lx - 0x%08lx   (%4ld MB)\n"
774 		"      .init : 0x%08lx - 0x%08lx   (%4ld kB)\n"
775 		"      .data : 0x%08lx - 0x%08lx   (%4ld kB)\n"
776 		"      .text : 0x%08lx - 0x%08lx   (%4ld kB)\n",
777 		FIXADDR_START, FIXADDR_TOP,
778 		(FIXADDR_TOP - FIXADDR_START) >> 10,
779 
780 #ifdef CONFIG_HIGHMEM
781 		PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE,
782 		(LAST_PKMAP*PAGE_SIZE) >> 10,
783 #endif
784 
785 		VMALLOC_START, VMALLOC_END,
786 		(VMALLOC_END - VMALLOC_START) >> 20,
787 
788 		(unsigned long)__va(0), (unsigned long)high_memory,
789 		((unsigned long)high_memory - (unsigned long)__va(0)) >> 20,
790 
791 		(unsigned long)&__init_begin, (unsigned long)&__init_end,
792 		((unsigned long)&__init_end -
793 		 (unsigned long)&__init_begin) >> 10,
794 
795 		(unsigned long)&_etext, (unsigned long)&_edata,
796 		((unsigned long)&_edata - (unsigned long)&_etext) >> 10,
797 
798 		(unsigned long)&_text, (unsigned long)&_etext,
799 		((unsigned long)&_etext - (unsigned long)&_text) >> 10);
800 
801 	/*
802 	 * Check boundaries twice: Some fundamental inconsistencies can
803 	 * be detected at build time already.
804 	 */
805 #define __FIXADDR_TOP (-PAGE_SIZE)
806 #ifdef CONFIG_HIGHMEM
807 	BUILD_BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE	> FIXADDR_START);
808 	BUILD_BUG_ON(VMALLOC_END			> PKMAP_BASE);
809 #endif
810 #define high_memory (-128UL << 20)
811 	BUILD_BUG_ON(VMALLOC_START			>= VMALLOC_END);
812 #undef high_memory
813 #undef __FIXADDR_TOP
814 
815 #ifdef CONFIG_HIGHMEM
816 	BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE	> FIXADDR_START);
817 	BUG_ON(VMALLOC_END				> PKMAP_BASE);
818 #endif
819 	BUG_ON(VMALLOC_START				>= VMALLOC_END);
820 	BUG_ON((unsigned long)high_memory		> VMALLOC_START);
821 
822 	test_wp_bit();
823 }
824 
825 #ifdef CONFIG_MEMORY_HOTPLUG
826 int arch_add_memory(int nid, u64 start, u64 size, bool want_memblock)
827 {
828 	unsigned long start_pfn = start >> PAGE_SHIFT;
829 	unsigned long nr_pages = size >> PAGE_SHIFT;
830 
831 	return __add_pages(nid, start_pfn, nr_pages, want_memblock);
832 }
833 
834 #ifdef CONFIG_MEMORY_HOTREMOVE
835 int arch_remove_memory(u64 start, u64 size)
836 {
837 	unsigned long start_pfn = start >> PAGE_SHIFT;
838 	unsigned long nr_pages = size >> PAGE_SHIFT;
839 	struct zone *zone;
840 
841 	zone = page_zone(pfn_to_page(start_pfn));
842 	return __remove_pages(zone, start_pfn, nr_pages);
843 }
844 #endif
845 #endif
846 
847 int kernel_set_to_readonly __read_mostly;
848 
849 void set_kernel_text_rw(void)
850 {
851 	unsigned long start = PFN_ALIGN(_text);
852 	unsigned long size = PFN_ALIGN(_etext) - start;
853 
854 	if (!kernel_set_to_readonly)
855 		return;
856 
857 	pr_debug("Set kernel text: %lx - %lx for read write\n",
858 		 start, start+size);
859 
860 	set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
861 }
862 
863 void set_kernel_text_ro(void)
864 {
865 	unsigned long start = PFN_ALIGN(_text);
866 	unsigned long size = PFN_ALIGN(_etext) - start;
867 
868 	if (!kernel_set_to_readonly)
869 		return;
870 
871 	pr_debug("Set kernel text: %lx - %lx for read only\n",
872 		 start, start+size);
873 
874 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
875 }
876 
877 static void mark_nxdata_nx(void)
878 {
879 	/*
880 	 * When this called, init has already been executed and released,
881 	 * so everything past _etext should be NX.
882 	 */
883 	unsigned long start = PFN_ALIGN(_etext);
884 	/*
885 	 * This comes from is_kernel_text upper limit. Also HPAGE where used:
886 	 */
887 	unsigned long size = (((unsigned long)__init_end + HPAGE_SIZE) & HPAGE_MASK) - start;
888 
889 	if (__supported_pte_mask & _PAGE_NX)
890 		printk(KERN_INFO "NX-protecting the kernel data: %luk\n", size >> 10);
891 	set_pages_nx(virt_to_page(start), size >> PAGE_SHIFT);
892 }
893 
894 void mark_rodata_ro(void)
895 {
896 	unsigned long start = PFN_ALIGN(_text);
897 	unsigned long size = PFN_ALIGN(_etext) - start;
898 
899 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
900 	printk(KERN_INFO "Write protecting the kernel text: %luk\n",
901 		size >> 10);
902 
903 	kernel_set_to_readonly = 1;
904 
905 #ifdef CONFIG_CPA_DEBUG
906 	printk(KERN_INFO "Testing CPA: Reverting %lx-%lx\n",
907 		start, start+size);
908 	set_pages_rw(virt_to_page(start), size>>PAGE_SHIFT);
909 
910 	printk(KERN_INFO "Testing CPA: write protecting again\n");
911 	set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
912 #endif
913 
914 	start += size;
915 	size = (unsigned long)__end_rodata - start;
916 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
917 	printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
918 		size >> 10);
919 
920 #ifdef CONFIG_CPA_DEBUG
921 	printk(KERN_INFO "Testing CPA: undo %lx-%lx\n", start, start + size);
922 	set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
923 
924 	printk(KERN_INFO "Testing CPA: write protecting again\n");
925 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
926 #endif
927 	mark_nxdata_nx();
928 	if (__supported_pte_mask & _PAGE_NX)
929 		debug_checkwx();
930 }
931