xref: /openbmc/linux/arch/x86/mm/init_32.c (revision 4bb1e4e7)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *
4  *  Copyright (C) 1995  Linus Torvalds
5  *
6  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
7  */
8 
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/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/cpu_entry_area.h>
54 #include <asm/init.h>
55 
56 #include "mm_internal.h"
57 
58 unsigned long highstart_pfn, highend_pfn;
59 
60 bool __read_mostly __vmalloc_start_set = false;
61 
62 /*
63  * Creates a middle page table and puts a pointer to it in the
64  * given global directory entry. This only returns the gd entry
65  * in non-PAE compilation mode, since the middle layer is folded.
66  */
67 static pmd_t * __init one_md_table_init(pgd_t *pgd)
68 {
69 	p4d_t *p4d;
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 		p4d = p4d_offset(pgd, 0);
79 		pud = pud_offset(p4d, 0);
80 		BUG_ON(pmd_table != pmd_offset(pud, 0));
81 
82 		return pmd_table;
83 	}
84 #endif
85 	p4d = p4d_offset(pgd, 0);
86 	pud = pud_offset(p4d, 0);
87 	pmd_table = pmd_offset(pud, 0);
88 
89 	return pmd_table;
90 }
91 
92 /*
93  * Create a page table and place a pointer to it in a middle page
94  * directory entry:
95  */
96 static pte_t * __init one_page_table_init(pmd_t *pmd)
97 {
98 	if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
99 		pte_t *page_table = (pte_t *)alloc_low_page();
100 
101 		paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);
102 		set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
103 		BUG_ON(page_table != pte_offset_kernel(pmd, 0));
104 	}
105 
106 	return pte_offset_kernel(pmd, 0);
107 }
108 
109 pmd_t * __init populate_extra_pmd(unsigned long vaddr)
110 {
111 	int pgd_idx = pgd_index(vaddr);
112 	int pmd_idx = pmd_index(vaddr);
113 
114 	return one_md_table_init(swapper_pg_dir + pgd_idx) + pmd_idx;
115 }
116 
117 pte_t * __init populate_extra_pte(unsigned long vaddr)
118 {
119 	int pte_idx = pte_index(vaddr);
120 	pmd_t *pmd;
121 
122 	pmd = populate_extra_pmd(vaddr);
123 	return one_page_table_init(pmd) + pte_idx;
124 }
125 
126 static unsigned long __init
127 page_table_range_init_count(unsigned long start, unsigned long end)
128 {
129 	unsigned long count = 0;
130 #ifdef CONFIG_HIGHMEM
131 	int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
132 	int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
133 	int pgd_idx, pmd_idx;
134 	unsigned long vaddr;
135 
136 	if (pmd_idx_kmap_begin == pmd_idx_kmap_end)
137 		return 0;
138 
139 	vaddr = start;
140 	pgd_idx = pgd_index(vaddr);
141 	pmd_idx = pmd_index(vaddr);
142 
143 	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd_idx++) {
144 		for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
145 							pmd_idx++) {
146 			if ((vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin &&
147 			    (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end)
148 				count++;
149 			vaddr += PMD_SIZE;
150 		}
151 		pmd_idx = 0;
152 	}
153 #endif
154 	return count;
155 }
156 
157 static pte_t *__init page_table_kmap_check(pte_t *pte, pmd_t *pmd,
158 					   unsigned long vaddr, pte_t *lastpte,
159 					   void **adr)
160 {
161 #ifdef CONFIG_HIGHMEM
162 	/*
163 	 * Something (early fixmap) may already have put a pte
164 	 * page here, which causes the page table allocation
165 	 * to become nonlinear. Attempt to fix it, and if it
166 	 * is still nonlinear then we have to bug.
167 	 */
168 	int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
169 	int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
170 
171 	if (pmd_idx_kmap_begin != pmd_idx_kmap_end
172 	    && (vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin
173 	    && (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end) {
174 		pte_t *newpte;
175 		int i;
176 
177 		BUG_ON(after_bootmem);
178 		newpte = *adr;
179 		for (i = 0; i < PTRS_PER_PTE; i++)
180 			set_pte(newpte + i, pte[i]);
181 		*adr = (void *)(((unsigned long)(*adr)) + PAGE_SIZE);
182 
183 		paravirt_alloc_pte(&init_mm, __pa(newpte) >> PAGE_SHIFT);
184 		set_pmd(pmd, __pmd(__pa(newpte)|_PAGE_TABLE));
185 		BUG_ON(newpte != pte_offset_kernel(pmd, 0));
186 		__flush_tlb_all();
187 
188 		paravirt_release_pte(__pa(pte) >> PAGE_SHIFT);
189 		pte = newpte;
190 	}
191 	BUG_ON(vaddr < fix_to_virt(FIX_KMAP_BEGIN - 1)
192 	       && vaddr > fix_to_virt(FIX_KMAP_END)
193 	       && lastpte && lastpte + PTRS_PER_PTE != pte);
194 #endif
195 	return pte;
196 }
197 
198 /*
199  * This function initializes a certain range of kernel virtual memory
200  * with new bootmem page tables, everywhere page tables are missing in
201  * the given range.
202  *
203  * NOTE: The pagetables are allocated contiguous on the physical space
204  * so we can cache the place of the first one and move around without
205  * checking the pgd every time.
206  */
207 static void __init
208 page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd_base)
209 {
210 	int pgd_idx, pmd_idx;
211 	unsigned long vaddr;
212 	pgd_t *pgd;
213 	pmd_t *pmd;
214 	pte_t *pte = NULL;
215 	unsigned long count = page_table_range_init_count(start, end);
216 	void *adr = NULL;
217 
218 	if (count)
219 		adr = alloc_low_pages(count);
220 
221 	vaddr = start;
222 	pgd_idx = pgd_index(vaddr);
223 	pmd_idx = pmd_index(vaddr);
224 	pgd = pgd_base + pgd_idx;
225 
226 	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
227 		pmd = one_md_table_init(pgd);
228 		pmd = pmd + pmd_index(vaddr);
229 		for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
230 							pmd++, pmd_idx++) {
231 			pte = page_table_kmap_check(one_page_table_init(pmd),
232 						    pmd, vaddr, pte, &adr);
233 
234 			vaddr += PMD_SIZE;
235 		}
236 		pmd_idx = 0;
237 	}
238 }
239 
240 static inline int is_kernel_text(unsigned long addr)
241 {
242 	if (addr >= (unsigned long)_text && addr <= (unsigned long)__init_end)
243 		return 1;
244 	return 0;
245 }
246 
247 /*
248  * This maps the physical memory to kernel virtual address space, a total
249  * of max_low_pfn pages, by creating page tables starting from address
250  * PAGE_OFFSET:
251  */
252 unsigned long __init
253 kernel_physical_mapping_init(unsigned long start,
254 			     unsigned long end,
255 			     unsigned long page_size_mask)
256 {
257 	int use_pse = page_size_mask == (1<<PG_LEVEL_2M);
258 	unsigned long last_map_addr = end;
259 	unsigned long start_pfn, end_pfn;
260 	pgd_t *pgd_base = swapper_pg_dir;
261 	int pgd_idx, pmd_idx, pte_ofs;
262 	unsigned long pfn;
263 	pgd_t *pgd;
264 	pmd_t *pmd;
265 	pte_t *pte;
266 	unsigned pages_2m, pages_4k;
267 	int mapping_iter;
268 
269 	start_pfn = start >> PAGE_SHIFT;
270 	end_pfn = end >> PAGE_SHIFT;
271 
272 	/*
273 	 * First iteration will setup identity mapping using large/small pages
274 	 * based on use_pse, with other attributes same as set by
275 	 * the early code in head_32.S
276 	 *
277 	 * Second iteration will setup the appropriate attributes (NX, GLOBAL..)
278 	 * as desired for the kernel identity mapping.
279 	 *
280 	 * This two pass mechanism conforms to the TLB app note which says:
281 	 *
282 	 *     "Software should not write to a paging-structure entry in a way
283 	 *      that would change, for any linear address, both the page size
284 	 *      and either the page frame or attributes."
285 	 */
286 	mapping_iter = 1;
287 
288 	if (!boot_cpu_has(X86_FEATURE_PSE))
289 		use_pse = 0;
290 
291 repeat:
292 	pages_2m = pages_4k = 0;
293 	pfn = start_pfn;
294 	pgd_idx = pgd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
295 	pgd = pgd_base + pgd_idx;
296 	for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
297 		pmd = one_md_table_init(pgd);
298 
299 		if (pfn >= end_pfn)
300 			continue;
301 #ifdef CONFIG_X86_PAE
302 		pmd_idx = pmd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
303 		pmd += pmd_idx;
304 #else
305 		pmd_idx = 0;
306 #endif
307 		for (; pmd_idx < PTRS_PER_PMD && pfn < end_pfn;
308 		     pmd++, pmd_idx++) {
309 			unsigned int addr = pfn * PAGE_SIZE + PAGE_OFFSET;
310 
311 			/*
312 			 * Map with big pages if possible, otherwise
313 			 * create normal page tables:
314 			 */
315 			if (use_pse) {
316 				unsigned int addr2;
317 				pgprot_t prot = PAGE_KERNEL_LARGE;
318 				/*
319 				 * first pass will use the same initial
320 				 * identity mapping attribute + _PAGE_PSE.
321 				 */
322 				pgprot_t init_prot =
323 					__pgprot(PTE_IDENT_ATTR |
324 						 _PAGE_PSE);
325 
326 				pfn &= PMD_MASK >> PAGE_SHIFT;
327 				addr2 = (pfn + PTRS_PER_PTE-1) * PAGE_SIZE +
328 					PAGE_OFFSET + PAGE_SIZE-1;
329 
330 				if (is_kernel_text(addr) ||
331 				    is_kernel_text(addr2))
332 					prot = PAGE_KERNEL_LARGE_EXEC;
333 
334 				pages_2m++;
335 				if (mapping_iter == 1)
336 					set_pmd(pmd, pfn_pmd(pfn, init_prot));
337 				else
338 					set_pmd(pmd, pfn_pmd(pfn, prot));
339 
340 				pfn += PTRS_PER_PTE;
341 				continue;
342 			}
343 			pte = one_page_table_init(pmd);
344 
345 			pte_ofs = pte_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
346 			pte += pte_ofs;
347 			for (; pte_ofs < PTRS_PER_PTE && pfn < end_pfn;
348 			     pte++, pfn++, pte_ofs++, addr += PAGE_SIZE) {
349 				pgprot_t prot = PAGE_KERNEL;
350 				/*
351 				 * first pass will use the same initial
352 				 * identity mapping attribute.
353 				 */
354 				pgprot_t init_prot = __pgprot(PTE_IDENT_ATTR);
355 
356 				if (is_kernel_text(addr))
357 					prot = PAGE_KERNEL_EXEC;
358 
359 				pages_4k++;
360 				if (mapping_iter == 1) {
361 					set_pte(pte, pfn_pte(pfn, init_prot));
362 					last_map_addr = (pfn << PAGE_SHIFT) + PAGE_SIZE;
363 				} else
364 					set_pte(pte, pfn_pte(pfn, prot));
365 			}
366 		}
367 	}
368 	if (mapping_iter == 1) {
369 		/*
370 		 * update direct mapping page count only in the first
371 		 * iteration.
372 		 */
373 		update_page_count(PG_LEVEL_2M, pages_2m);
374 		update_page_count(PG_LEVEL_4K, pages_4k);
375 
376 		/*
377 		 * local global flush tlb, which will flush the previous
378 		 * mappings present in both small and large page TLB's.
379 		 */
380 		__flush_tlb_all();
381 
382 		/*
383 		 * Second iteration will set the actual desired PTE attributes.
384 		 */
385 		mapping_iter = 2;
386 		goto repeat;
387 	}
388 	return last_map_addr;
389 }
390 
391 pte_t *kmap_pte;
392 
393 static inline pte_t *kmap_get_fixmap_pte(unsigned long vaddr)
394 {
395 	pgd_t *pgd = pgd_offset_k(vaddr);
396 	p4d_t *p4d = p4d_offset(pgd, vaddr);
397 	pud_t *pud = pud_offset(p4d, vaddr);
398 	pmd_t *pmd = pmd_offset(pud, vaddr);
399 	return pte_offset_kernel(pmd, vaddr);
400 }
401 
402 static void __init kmap_init(void)
403 {
404 	unsigned long kmap_vstart;
405 
406 	/*
407 	 * Cache the first kmap pte:
408 	 */
409 	kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
410 	kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
411 }
412 
413 #ifdef CONFIG_HIGHMEM
414 static void __init permanent_kmaps_init(pgd_t *pgd_base)
415 {
416 	unsigned long vaddr;
417 	pgd_t *pgd;
418 	p4d_t *p4d;
419 	pud_t *pud;
420 	pmd_t *pmd;
421 	pte_t *pte;
422 
423 	vaddr = PKMAP_BASE;
424 	page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
425 
426 	pgd = swapper_pg_dir + pgd_index(vaddr);
427 	p4d = p4d_offset(pgd, vaddr);
428 	pud = pud_offset(p4d, vaddr);
429 	pmd = pmd_offset(pud, vaddr);
430 	pte = pte_offset_kernel(pmd, vaddr);
431 	pkmap_page_table = pte;
432 }
433 
434 void __init add_highpages_with_active_regions(int nid,
435 			 unsigned long start_pfn, unsigned long end_pfn)
436 {
437 	phys_addr_t start, end;
438 	u64 i;
439 
440 	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &start, &end, NULL) {
441 		unsigned long pfn = clamp_t(unsigned long, PFN_UP(start),
442 					    start_pfn, end_pfn);
443 		unsigned long e_pfn = clamp_t(unsigned long, PFN_DOWN(end),
444 					      start_pfn, end_pfn);
445 		for ( ; pfn < e_pfn; pfn++)
446 			if (pfn_valid(pfn))
447 				free_highmem_page(pfn_to_page(pfn));
448 	}
449 }
450 #else
451 static inline void permanent_kmaps_init(pgd_t *pgd_base)
452 {
453 }
454 #endif /* CONFIG_HIGHMEM */
455 
456 void __init sync_initial_page_table(void)
457 {
458 	clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,
459 			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
460 			KERNEL_PGD_PTRS);
461 
462 	/*
463 	 * sync back low identity map too.  It is used for example
464 	 * in the 32-bit EFI stub.
465 	 */
466 	clone_pgd_range(initial_page_table,
467 			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
468 			min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
469 }
470 
471 void __init native_pagetable_init(void)
472 {
473 	unsigned long pfn, va;
474 	pgd_t *pgd, *base = swapper_pg_dir;
475 	p4d_t *p4d;
476 	pud_t *pud;
477 	pmd_t *pmd;
478 	pte_t *pte;
479 
480 	/*
481 	 * Remove any mappings which extend past the end of physical
482 	 * memory from the boot time page table.
483 	 * In virtual address space, we should have at least two pages
484 	 * from VMALLOC_END to pkmap or fixmap according to VMALLOC_END
485 	 * definition. And max_low_pfn is set to VMALLOC_END physical
486 	 * address. If initial memory mapping is doing right job, we
487 	 * should have pte used near max_low_pfn or one pmd is not present.
488 	 */
489 	for (pfn = max_low_pfn; pfn < 1<<(32-PAGE_SHIFT); pfn++) {
490 		va = PAGE_OFFSET + (pfn<<PAGE_SHIFT);
491 		pgd = base + pgd_index(va);
492 		if (!pgd_present(*pgd))
493 			break;
494 
495 		p4d = p4d_offset(pgd, va);
496 		pud = pud_offset(p4d, va);
497 		pmd = pmd_offset(pud, va);
498 		if (!pmd_present(*pmd))
499 			break;
500 
501 		/* should not be large page here */
502 		if (pmd_large(*pmd)) {
503 			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",
504 				pfn, pmd, __pa(pmd));
505 			BUG_ON(1);
506 		}
507 
508 		pte = pte_offset_kernel(pmd, va);
509 		if (!pte_present(*pte))
510 			break;
511 
512 		printk(KERN_DEBUG "clearing pte for ram above max_low_pfn: pfn: %lx pmd: %p pmd phys: %lx pte: %p pte phys: %lx\n",
513 				pfn, pmd, __pa(pmd), pte, __pa(pte));
514 		pte_clear(NULL, va, pte);
515 	}
516 	paravirt_alloc_pmd(&init_mm, __pa(base) >> PAGE_SHIFT);
517 	paging_init();
518 }
519 
520 /*
521  * Build a proper pagetable for the kernel mappings.  Up until this
522  * point, we've been running on some set of pagetables constructed by
523  * the boot process.
524  *
525  * If we're booting on native hardware, this will be a pagetable
526  * constructed in arch/x86/kernel/head_32.S.  The root of the
527  * pagetable will be swapper_pg_dir.
528  *
529  * If we're booting paravirtualized under a hypervisor, then there are
530  * more options: we may already be running PAE, and the pagetable may
531  * or may not be based in swapper_pg_dir.  In any case,
532  * paravirt_pagetable_init() will set up swapper_pg_dir
533  * appropriately for the rest of the initialization to work.
534  *
535  * In general, pagetable_init() assumes that the pagetable may already
536  * be partially populated, and so it avoids stomping on any existing
537  * mappings.
538  */
539 void __init early_ioremap_page_table_range_init(void)
540 {
541 	pgd_t *pgd_base = swapper_pg_dir;
542 	unsigned long vaddr, end;
543 
544 	/*
545 	 * Fixed mappings, only the page table structure has to be
546 	 * created - mappings will be set by set_fixmap():
547 	 */
548 	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
549 	end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
550 	page_table_range_init(vaddr, end, pgd_base);
551 	early_ioremap_reset();
552 }
553 
554 static void __init pagetable_init(void)
555 {
556 	pgd_t *pgd_base = swapper_pg_dir;
557 
558 	permanent_kmaps_init(pgd_base);
559 }
560 
561 #define DEFAULT_PTE_MASK ~(_PAGE_NX | _PAGE_GLOBAL)
562 /* Bits supported by the hardware: */
563 pteval_t __supported_pte_mask __read_mostly = DEFAULT_PTE_MASK;
564 /* Bits allowed in normal kernel mappings: */
565 pteval_t __default_kernel_pte_mask __read_mostly = DEFAULT_PTE_MASK;
566 EXPORT_SYMBOL_GPL(__supported_pte_mask);
567 /* Used in PAGE_KERNEL_* macros which are reasonably used out-of-tree: */
568 EXPORT_SYMBOL(__default_kernel_pte_mask);
569 
570 /* user-defined highmem size */
571 static unsigned int highmem_pages = -1;
572 
573 /*
574  * highmem=size forces highmem to be exactly 'size' bytes.
575  * This works even on boxes that have no highmem otherwise.
576  * This also works to reduce highmem size on bigger boxes.
577  */
578 static int __init parse_highmem(char *arg)
579 {
580 	if (!arg)
581 		return -EINVAL;
582 
583 	highmem_pages = memparse(arg, &arg) >> PAGE_SHIFT;
584 	return 0;
585 }
586 early_param("highmem", parse_highmem);
587 
588 #define MSG_HIGHMEM_TOO_BIG \
589 	"highmem size (%luMB) is bigger than pages available (%luMB)!\n"
590 
591 #define MSG_LOWMEM_TOO_SMALL \
592 	"highmem size (%luMB) results in <64MB lowmem, ignoring it!\n"
593 /*
594  * All of RAM fits into lowmem - but if user wants highmem
595  * artificially via the highmem=x boot parameter then create
596  * it:
597  */
598 static void __init lowmem_pfn_init(void)
599 {
600 	/* max_low_pfn is 0, we already have early_res support */
601 	max_low_pfn = max_pfn;
602 
603 	if (highmem_pages == -1)
604 		highmem_pages = 0;
605 #ifdef CONFIG_HIGHMEM
606 	if (highmem_pages >= max_pfn) {
607 		printk(KERN_ERR MSG_HIGHMEM_TOO_BIG,
608 			pages_to_mb(highmem_pages), pages_to_mb(max_pfn));
609 		highmem_pages = 0;
610 	}
611 	if (highmem_pages) {
612 		if (max_low_pfn - highmem_pages < 64*1024*1024/PAGE_SIZE) {
613 			printk(KERN_ERR MSG_LOWMEM_TOO_SMALL,
614 				pages_to_mb(highmem_pages));
615 			highmem_pages = 0;
616 		}
617 		max_low_pfn -= highmem_pages;
618 	}
619 #else
620 	if (highmem_pages)
621 		printk(KERN_ERR "ignoring highmem size on non-highmem kernel!\n");
622 #endif
623 }
624 
625 #define MSG_HIGHMEM_TOO_SMALL \
626 	"only %luMB highmem pages available, ignoring highmem size of %luMB!\n"
627 
628 #define MSG_HIGHMEM_TRIMMED \
629 	"Warning: only 4GB will be used. Use a HIGHMEM64G enabled kernel!\n"
630 /*
631  * We have more RAM than fits into lowmem - we try to put it into
632  * highmem, also taking the highmem=x boot parameter into account:
633  */
634 static void __init highmem_pfn_init(void)
635 {
636 	max_low_pfn = MAXMEM_PFN;
637 
638 	if (highmem_pages == -1)
639 		highmem_pages = max_pfn - MAXMEM_PFN;
640 
641 	if (highmem_pages + MAXMEM_PFN < max_pfn)
642 		max_pfn = MAXMEM_PFN + highmem_pages;
643 
644 	if (highmem_pages + MAXMEM_PFN > max_pfn) {
645 		printk(KERN_WARNING MSG_HIGHMEM_TOO_SMALL,
646 			pages_to_mb(max_pfn - MAXMEM_PFN),
647 			pages_to_mb(highmem_pages));
648 		highmem_pages = 0;
649 	}
650 #ifndef CONFIG_HIGHMEM
651 	/* Maximum memory usable is what is directly addressable */
652 	printk(KERN_WARNING "Warning only %ldMB will be used.\n", MAXMEM>>20);
653 	if (max_pfn > MAX_NONPAE_PFN)
654 		printk(KERN_WARNING "Use a HIGHMEM64G enabled kernel.\n");
655 	else
656 		printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
657 	max_pfn = MAXMEM_PFN;
658 #else /* !CONFIG_HIGHMEM */
659 #ifndef CONFIG_HIGHMEM64G
660 	if (max_pfn > MAX_NONPAE_PFN) {
661 		max_pfn = MAX_NONPAE_PFN;
662 		printk(KERN_WARNING MSG_HIGHMEM_TRIMMED);
663 	}
664 #endif /* !CONFIG_HIGHMEM64G */
665 #endif /* !CONFIG_HIGHMEM */
666 }
667 
668 /*
669  * Determine low and high memory ranges:
670  */
671 void __init find_low_pfn_range(void)
672 {
673 	/* it could update max_pfn */
674 
675 	if (max_pfn <= MAXMEM_PFN)
676 		lowmem_pfn_init();
677 	else
678 		highmem_pfn_init();
679 }
680 
681 #ifndef CONFIG_NEED_MULTIPLE_NODES
682 void __init initmem_init(void)
683 {
684 #ifdef CONFIG_HIGHMEM
685 	highstart_pfn = highend_pfn = max_pfn;
686 	if (max_pfn > max_low_pfn)
687 		highstart_pfn = max_low_pfn;
688 	printk(KERN_NOTICE "%ldMB HIGHMEM available.\n",
689 		pages_to_mb(highend_pfn - highstart_pfn));
690 	high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
691 #else
692 	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
693 #endif
694 
695 	memblock_set_node(0, PHYS_ADDR_MAX, &memblock.memory, 0);
696 	sparse_memory_present_with_active_regions(0);
697 
698 #ifdef CONFIG_FLATMEM
699 	max_mapnr = IS_ENABLED(CONFIG_HIGHMEM) ? highend_pfn : max_low_pfn;
700 #endif
701 	__vmalloc_start_set = true;
702 
703 	printk(KERN_NOTICE "%ldMB LOWMEM available.\n",
704 			pages_to_mb(max_low_pfn));
705 
706 	setup_bootmem_allocator();
707 }
708 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
709 
710 void __init setup_bootmem_allocator(void)
711 {
712 	printk(KERN_INFO "  mapped low ram: 0 - %08lx\n",
713 		 max_pfn_mapped<<PAGE_SHIFT);
714 	printk(KERN_INFO "  low ram: 0 - %08lx\n", max_low_pfn<<PAGE_SHIFT);
715 }
716 
717 /*
718  * paging_init() sets up the page tables - note that the first 8MB are
719  * already mapped by head.S.
720  *
721  * This routines also unmaps the page at virtual kernel address 0, so
722  * that we can trap those pesky NULL-reference errors in the kernel.
723  */
724 void __init paging_init(void)
725 {
726 	pagetable_init();
727 
728 	__flush_tlb_all();
729 
730 	kmap_init();
731 
732 	/*
733 	 * NOTE: at this point the bootmem allocator is fully available.
734 	 */
735 	olpc_dt_build_devicetree();
736 	sparse_memory_present_with_active_regions(MAX_NUMNODES);
737 	sparse_init();
738 	zone_sizes_init();
739 }
740 
741 /*
742  * Test if the WP bit works in supervisor mode. It isn't supported on 386's
743  * and also on some strange 486's. All 586+'s are OK. This used to involve
744  * black magic jumps to work around some nasty CPU bugs, but fortunately the
745  * switch to using exceptions got rid of all that.
746  */
747 static void __init test_wp_bit(void)
748 {
749 	char z = 0;
750 
751 	printk(KERN_INFO "Checking if this processor honours the WP bit even in supervisor mode...");
752 
753 	__set_fixmap(FIX_WP_TEST, __pa_symbol(empty_zero_page), PAGE_KERNEL_RO);
754 
755 	if (probe_kernel_write((char *)fix_to_virt(FIX_WP_TEST), &z, 1)) {
756 		clear_fixmap(FIX_WP_TEST);
757 		printk(KERN_CONT "Ok.\n");
758 		return;
759 	}
760 
761 	printk(KERN_CONT "No.\n");
762 	panic("Linux doesn't support CPUs with broken WP.");
763 }
764 
765 void __init mem_init(void)
766 {
767 	pci_iommu_alloc();
768 
769 #ifdef CONFIG_FLATMEM
770 	BUG_ON(!mem_map);
771 #endif
772 	/*
773 	 * With CONFIG_DEBUG_PAGEALLOC initialization of highmem pages has to
774 	 * be done before memblock_free_all(). Memblock use free low memory for
775 	 * temporary data (see find_range_array()) and for this purpose can use
776 	 * pages that was already passed to the buddy allocator, hence marked as
777 	 * not accessible in the page tables when compiled with
778 	 * CONFIG_DEBUG_PAGEALLOC. Otherwise order of initialization is not
779 	 * important here.
780 	 */
781 	set_highmem_pages_init();
782 
783 	/* this will put all low memory onto the freelists */
784 	memblock_free_all();
785 
786 	after_bootmem = 1;
787 	x86_init.hyper.init_after_bootmem();
788 
789 	mem_init_print_info(NULL);
790 	printk(KERN_INFO "virtual kernel memory layout:\n"
791 		"    fixmap  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
792 		"  cpu_entry : 0x%08lx - 0x%08lx   (%4ld kB)\n"
793 #ifdef CONFIG_HIGHMEM
794 		"    pkmap   : 0x%08lx - 0x%08lx   (%4ld kB)\n"
795 #endif
796 		"    vmalloc : 0x%08lx - 0x%08lx   (%4ld MB)\n"
797 		"    lowmem  : 0x%08lx - 0x%08lx   (%4ld MB)\n"
798 		"      .init : 0x%08lx - 0x%08lx   (%4ld kB)\n"
799 		"      .data : 0x%08lx - 0x%08lx   (%4ld kB)\n"
800 		"      .text : 0x%08lx - 0x%08lx   (%4ld kB)\n",
801 		FIXADDR_START, FIXADDR_TOP,
802 		(FIXADDR_TOP - FIXADDR_START) >> 10,
803 
804 		CPU_ENTRY_AREA_BASE,
805 		CPU_ENTRY_AREA_BASE + CPU_ENTRY_AREA_MAP_SIZE,
806 		CPU_ENTRY_AREA_MAP_SIZE >> 10,
807 
808 #ifdef CONFIG_HIGHMEM
809 		PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE,
810 		(LAST_PKMAP*PAGE_SIZE) >> 10,
811 #endif
812 
813 		VMALLOC_START, VMALLOC_END,
814 		(VMALLOC_END - VMALLOC_START) >> 20,
815 
816 		(unsigned long)__va(0), (unsigned long)high_memory,
817 		((unsigned long)high_memory - (unsigned long)__va(0)) >> 20,
818 
819 		(unsigned long)&__init_begin, (unsigned long)&__init_end,
820 		((unsigned long)&__init_end -
821 		 (unsigned long)&__init_begin) >> 10,
822 
823 		(unsigned long)&_etext, (unsigned long)&_edata,
824 		((unsigned long)&_edata - (unsigned long)&_etext) >> 10,
825 
826 		(unsigned long)&_text, (unsigned long)&_etext,
827 		((unsigned long)&_etext - (unsigned long)&_text) >> 10);
828 
829 	/*
830 	 * Check boundaries twice: Some fundamental inconsistencies can
831 	 * be detected at build time already.
832 	 */
833 #define __FIXADDR_TOP (-PAGE_SIZE)
834 #ifdef CONFIG_HIGHMEM
835 	BUILD_BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE	> FIXADDR_START);
836 	BUILD_BUG_ON(VMALLOC_END			> PKMAP_BASE);
837 #endif
838 #define high_memory (-128UL << 20)
839 	BUILD_BUG_ON(VMALLOC_START			>= VMALLOC_END);
840 #undef high_memory
841 #undef __FIXADDR_TOP
842 
843 #ifdef CONFIG_HIGHMEM
844 	BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE	> FIXADDR_START);
845 	BUG_ON(VMALLOC_END				> PKMAP_BASE);
846 #endif
847 	BUG_ON(VMALLOC_START				>= VMALLOC_END);
848 	BUG_ON((unsigned long)high_memory		> VMALLOC_START);
849 
850 	test_wp_bit();
851 }
852 
853 #ifdef CONFIG_MEMORY_HOTPLUG
854 int arch_add_memory(int nid, u64 start, u64 size,
855 			struct mhp_restrictions *restrictions)
856 {
857 	unsigned long start_pfn = start >> PAGE_SHIFT;
858 	unsigned long nr_pages = size >> PAGE_SHIFT;
859 
860 	return __add_pages(nid, start_pfn, nr_pages, restrictions);
861 }
862 
863 void arch_remove_memory(int nid, u64 start, u64 size,
864 			struct vmem_altmap *altmap)
865 {
866 	unsigned long start_pfn = start >> PAGE_SHIFT;
867 	unsigned long nr_pages = size >> PAGE_SHIFT;
868 	struct zone *zone;
869 
870 	zone = page_zone(pfn_to_page(start_pfn));
871 	__remove_pages(zone, start_pfn, nr_pages, altmap);
872 }
873 #endif
874 
875 int kernel_set_to_readonly __read_mostly;
876 
877 void set_kernel_text_rw(void)
878 {
879 	unsigned long start = PFN_ALIGN(_text);
880 	unsigned long size = PFN_ALIGN(_etext) - start;
881 
882 	if (!kernel_set_to_readonly)
883 		return;
884 
885 	pr_debug("Set kernel text: %lx - %lx for read write\n",
886 		 start, start+size);
887 
888 	set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
889 }
890 
891 void set_kernel_text_ro(void)
892 {
893 	unsigned long start = PFN_ALIGN(_text);
894 	unsigned long size = PFN_ALIGN(_etext) - start;
895 
896 	if (!kernel_set_to_readonly)
897 		return;
898 
899 	pr_debug("Set kernel text: %lx - %lx for read only\n",
900 		 start, start+size);
901 
902 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
903 }
904 
905 static void mark_nxdata_nx(void)
906 {
907 	/*
908 	 * When this called, init has already been executed and released,
909 	 * so everything past _etext should be NX.
910 	 */
911 	unsigned long start = PFN_ALIGN(_etext);
912 	/*
913 	 * This comes from is_kernel_text upper limit. Also HPAGE where used:
914 	 */
915 	unsigned long size = (((unsigned long)__init_end + HPAGE_SIZE) & HPAGE_MASK) - start;
916 
917 	if (__supported_pte_mask & _PAGE_NX)
918 		printk(KERN_INFO "NX-protecting the kernel data: %luk\n", size >> 10);
919 	set_memory_nx(start, size >> PAGE_SHIFT);
920 }
921 
922 void mark_rodata_ro(void)
923 {
924 	unsigned long start = PFN_ALIGN(_text);
925 	unsigned long size = (unsigned long)__end_rodata - start;
926 
927 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
928 	pr_info("Write protecting kernel text and read-only data: %luk\n",
929 		size >> 10);
930 
931 	kernel_set_to_readonly = 1;
932 
933 #ifdef CONFIG_CPA_DEBUG
934 	pr_info("Testing CPA: Reverting %lx-%lx\n", start, start + size);
935 	set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
936 
937 	pr_info("Testing CPA: write protecting again\n");
938 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
939 #endif
940 	mark_nxdata_nx();
941 	if (__supported_pte_mask & _PAGE_NX)
942 		debug_checkwx();
943 }
944