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/dma.h>
39 #include <asm/fixmap.h>
40 #include <asm/e820/api.h>
41 #include <asm/apic.h>
42 #include <asm/bugs.h>
43 #include <asm/tlb.h>
44 #include <asm/tlbflush.h>
45 #include <asm/olpc_ofw.h>
46 #include <asm/pgalloc.h>
47 #include <asm/sections.h>
48 #include <asm/paravirt.h>
49 #include <asm/setup.h>
50 #include <asm/set_memory.h>
51 #include <asm/page_types.h>
52 #include <asm/cpu_entry_area.h>
53 #include <asm/init.h>
54 #include <asm/pgtable_areas.h>
55 #include <asm/numa.h>
56 
57 #include "mm_internal.h"
58 
59 unsigned long highstart_pfn, highend_pfn;
60 
61 bool __read_mostly __vmalloc_start_set = false;
62 
63 /*
64  * Creates a middle page table and puts a pointer to it in the
65  * given global directory entry. This only returns the gd entry
66  * in non-PAE compilation mode, since the middle layer is folded.
67  */
one_md_table_init(pgd_t * pgd)68 static pmd_t * __init one_md_table_init(pgd_t *pgd)
69 {
70 	p4d_t *p4d;
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 		p4d = p4d_offset(pgd, 0);
80 		pud = pud_offset(p4d, 0);
81 		BUG_ON(pmd_table != pmd_offset(pud, 0));
82 
83 		return pmd_table;
84 	}
85 #endif
86 	p4d = p4d_offset(pgd, 0);
87 	pud = pud_offset(p4d, 0);
88 	pmd_table = pmd_offset(pud, 0);
89 
90 	return pmd_table;
91 }
92 
93 /*
94  * Create a page table and place a pointer to it in a middle page
95  * directory entry:
96  */
one_page_table_init(pmd_t * pmd)97 static pte_t * __init one_page_table_init(pmd_t *pmd)
98 {
99 	if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
100 		pte_t *page_table = (pte_t *)alloc_low_page();
101 
102 		paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);
103 		set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
104 		BUG_ON(page_table != pte_offset_kernel(pmd, 0));
105 	}
106 
107 	return pte_offset_kernel(pmd, 0);
108 }
109 
populate_extra_pmd(unsigned long vaddr)110 pmd_t * __init populate_extra_pmd(unsigned long vaddr)
111 {
112 	int pgd_idx = pgd_index(vaddr);
113 	int pmd_idx = pmd_index(vaddr);
114 
115 	return one_md_table_init(swapper_pg_dir + pgd_idx) + pmd_idx;
116 }
117 
populate_extra_pte(unsigned long vaddr)118 pte_t * __init populate_extra_pte(unsigned long vaddr)
119 {
120 	int pte_idx = pte_index(vaddr);
121 	pmd_t *pmd;
122 
123 	pmd = populate_extra_pmd(vaddr);
124 	return one_page_table_init(pmd) + pte_idx;
125 }
126 
127 static unsigned long __init
page_table_range_init_count(unsigned long start,unsigned long end)128 page_table_range_init_count(unsigned long start, unsigned long end)
129 {
130 	unsigned long count = 0;
131 #ifdef CONFIG_HIGHMEM
132 	int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
133 	int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
134 	int pgd_idx, pmd_idx;
135 	unsigned long vaddr;
136 
137 	if (pmd_idx_kmap_begin == pmd_idx_kmap_end)
138 		return 0;
139 
140 	vaddr = start;
141 	pgd_idx = pgd_index(vaddr);
142 	pmd_idx = pmd_index(vaddr);
143 
144 	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd_idx++) {
145 		for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
146 							pmd_idx++) {
147 			if ((vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin &&
148 			    (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end)
149 				count++;
150 			vaddr += PMD_SIZE;
151 		}
152 		pmd_idx = 0;
153 	}
154 #endif
155 	return count;
156 }
157 
page_table_kmap_check(pte_t * pte,pmd_t * pmd,unsigned long vaddr,pte_t * lastpte,void ** adr)158 static pte_t *__init page_table_kmap_check(pte_t *pte, pmd_t *pmd,
159 					   unsigned long vaddr, pte_t *lastpte,
160 					   void **adr)
161 {
162 #ifdef CONFIG_HIGHMEM
163 	/*
164 	 * Something (early fixmap) may already have put a pte
165 	 * page here, which causes the page table allocation
166 	 * to become nonlinear. Attempt to fix it, and if it
167 	 * is still nonlinear then we have to bug.
168 	 */
169 	int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
170 	int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
171 
172 	if (pmd_idx_kmap_begin != pmd_idx_kmap_end
173 	    && (vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin
174 	    && (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end) {
175 		pte_t *newpte;
176 		int i;
177 
178 		BUG_ON(after_bootmem);
179 		newpte = *adr;
180 		for (i = 0; i < PTRS_PER_PTE; i++)
181 			set_pte(newpte + i, pte[i]);
182 		*adr = (void *)(((unsigned long)(*adr)) + PAGE_SIZE);
183 
184 		paravirt_alloc_pte(&init_mm, __pa(newpte) >> PAGE_SHIFT);
185 		set_pmd(pmd, __pmd(__pa(newpte)|_PAGE_TABLE));
186 		BUG_ON(newpte != pte_offset_kernel(pmd, 0));
187 		__flush_tlb_all();
188 
189 		paravirt_release_pte(__pa(pte) >> PAGE_SHIFT);
190 		pte = newpte;
191 	}
192 	BUG_ON(vaddr < fix_to_virt(FIX_KMAP_BEGIN - 1)
193 	       && vaddr > fix_to_virt(FIX_KMAP_END)
194 	       && lastpte && lastpte + PTRS_PER_PTE != pte);
195 #endif
196 	return pte;
197 }
198 
199 /*
200  * This function initializes a certain range of kernel virtual memory
201  * with new bootmem page tables, everywhere page tables are missing in
202  * the given range.
203  *
204  * NOTE: The pagetables are allocated contiguous on the physical space
205  * so we can cache the place of the first one and move around without
206  * checking the pgd every time.
207  */
208 static void __init
page_table_range_init(unsigned long start,unsigned long end,pgd_t * pgd_base)209 page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd_base)
210 {
211 	int pgd_idx, pmd_idx;
212 	unsigned long vaddr;
213 	pgd_t *pgd;
214 	pmd_t *pmd;
215 	pte_t *pte = NULL;
216 	unsigned long count = page_table_range_init_count(start, end);
217 	void *adr = NULL;
218 
219 	if (count)
220 		adr = alloc_low_pages(count);
221 
222 	vaddr = start;
223 	pgd_idx = pgd_index(vaddr);
224 	pmd_idx = pmd_index(vaddr);
225 	pgd = pgd_base + pgd_idx;
226 
227 	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
228 		pmd = one_md_table_init(pgd);
229 		pmd = pmd + pmd_index(vaddr);
230 		for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
231 							pmd++, pmd_idx++) {
232 			pte = page_table_kmap_check(one_page_table_init(pmd),
233 						    pmd, vaddr, pte, &adr);
234 
235 			vaddr += PMD_SIZE;
236 		}
237 		pmd_idx = 0;
238 	}
239 }
240 
is_x86_32_kernel_text(unsigned long addr)241 static inline int is_x86_32_kernel_text(unsigned long addr)
242 {
243 	if (addr >= (unsigned long)_text && addr <= (unsigned long)__init_end)
244 		return 1;
245 	return 0;
246 }
247 
248 /*
249  * This maps the physical memory to kernel virtual address space, a total
250  * of max_low_pfn pages, by creating page tables starting from address
251  * PAGE_OFFSET:
252  */
253 unsigned long __init
kernel_physical_mapping_init(unsigned long start,unsigned long end,unsigned long page_size_mask,pgprot_t prot)254 kernel_physical_mapping_init(unsigned long start,
255 			     unsigned long end,
256 			     unsigned long page_size_mask,
257 			     pgprot_t prot)
258 {
259 	int use_pse = page_size_mask == (1<<PG_LEVEL_2M);
260 	unsigned long last_map_addr = end;
261 	unsigned long start_pfn, end_pfn;
262 	pgd_t *pgd_base = swapper_pg_dir;
263 	int pgd_idx, pmd_idx, pte_ofs;
264 	unsigned long pfn;
265 	pgd_t *pgd;
266 	pmd_t *pmd;
267 	pte_t *pte;
268 	unsigned pages_2m, pages_4k;
269 	int mapping_iter;
270 
271 	start_pfn = start >> PAGE_SHIFT;
272 	end_pfn = end >> PAGE_SHIFT;
273 
274 	/*
275 	 * First iteration will setup identity mapping using large/small pages
276 	 * based on use_pse, with other attributes same as set by
277 	 * the early code in head_32.S
278 	 *
279 	 * Second iteration will setup the appropriate attributes (NX, GLOBAL..)
280 	 * as desired for the kernel identity mapping.
281 	 *
282 	 * This two pass mechanism conforms to the TLB app note which says:
283 	 *
284 	 *     "Software should not write to a paging-structure entry in a way
285 	 *      that would change, for any linear address, both the page size
286 	 *      and either the page frame or attributes."
287 	 */
288 	mapping_iter = 1;
289 
290 	if (!boot_cpu_has(X86_FEATURE_PSE))
291 		use_pse = 0;
292 
293 repeat:
294 	pages_2m = pages_4k = 0;
295 	pfn = start_pfn;
296 	pgd_idx = pgd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
297 	pgd = pgd_base + pgd_idx;
298 	for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
299 		pmd = one_md_table_init(pgd);
300 
301 		if (pfn >= end_pfn)
302 			continue;
303 #ifdef CONFIG_X86_PAE
304 		pmd_idx = pmd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
305 		pmd += pmd_idx;
306 #else
307 		pmd_idx = 0;
308 #endif
309 		for (; pmd_idx < PTRS_PER_PMD && pfn < end_pfn;
310 		     pmd++, pmd_idx++) {
311 			unsigned int addr = pfn * PAGE_SIZE + PAGE_OFFSET;
312 
313 			/*
314 			 * Map with big pages if possible, otherwise
315 			 * create normal page tables:
316 			 */
317 			if (use_pse) {
318 				unsigned int addr2;
319 				pgprot_t prot = PAGE_KERNEL_LARGE;
320 				/*
321 				 * first pass will use the same initial
322 				 * identity mapping attribute + _PAGE_PSE.
323 				 */
324 				pgprot_t init_prot =
325 					__pgprot(PTE_IDENT_ATTR |
326 						 _PAGE_PSE);
327 
328 				pfn &= PMD_MASK >> PAGE_SHIFT;
329 				addr2 = (pfn + PTRS_PER_PTE-1) * PAGE_SIZE +
330 					PAGE_OFFSET + PAGE_SIZE-1;
331 
332 				if (is_x86_32_kernel_text(addr) ||
333 				    is_x86_32_kernel_text(addr2))
334 					prot = PAGE_KERNEL_LARGE_EXEC;
335 
336 				pages_2m++;
337 				if (mapping_iter == 1)
338 					set_pmd(pmd, pfn_pmd(pfn, init_prot));
339 				else
340 					set_pmd(pmd, pfn_pmd(pfn, prot));
341 
342 				pfn += PTRS_PER_PTE;
343 				continue;
344 			}
345 			pte = one_page_table_init(pmd);
346 
347 			pte_ofs = pte_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
348 			pte += pte_ofs;
349 			for (; pte_ofs < PTRS_PER_PTE && pfn < end_pfn;
350 			     pte++, pfn++, pte_ofs++, addr += PAGE_SIZE) {
351 				pgprot_t prot = PAGE_KERNEL;
352 				/*
353 				 * first pass will use the same initial
354 				 * identity mapping attribute.
355 				 */
356 				pgprot_t init_prot = __pgprot(PTE_IDENT_ATTR);
357 
358 				if (is_x86_32_kernel_text(addr))
359 					prot = PAGE_KERNEL_EXEC;
360 
361 				pages_4k++;
362 				if (mapping_iter == 1) {
363 					set_pte(pte, pfn_pte(pfn, init_prot));
364 					last_map_addr = (pfn << PAGE_SHIFT) + PAGE_SIZE;
365 				} else
366 					set_pte(pte, pfn_pte(pfn, prot));
367 			}
368 		}
369 	}
370 	if (mapping_iter == 1) {
371 		/*
372 		 * update direct mapping page count only in the first
373 		 * iteration.
374 		 */
375 		update_page_count(PG_LEVEL_2M, pages_2m);
376 		update_page_count(PG_LEVEL_4K, pages_4k);
377 
378 		/*
379 		 * local global flush tlb, which will flush the previous
380 		 * mappings present in both small and large page TLB's.
381 		 */
382 		__flush_tlb_all();
383 
384 		/*
385 		 * Second iteration will set the actual desired PTE attributes.
386 		 */
387 		mapping_iter = 2;
388 		goto repeat;
389 	}
390 	return last_map_addr;
391 }
392 
393 #ifdef CONFIG_HIGHMEM
permanent_kmaps_init(pgd_t * pgd_base)394 static void __init permanent_kmaps_init(pgd_t *pgd_base)
395 {
396 	unsigned long vaddr = PKMAP_BASE;
397 
398 	page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
399 
400 	pkmap_page_table = virt_to_kpte(vaddr);
401 }
402 
add_highpages_with_active_regions(int nid,unsigned long start_pfn,unsigned long end_pfn)403 void __init add_highpages_with_active_regions(int nid,
404 			 unsigned long start_pfn, unsigned long end_pfn)
405 {
406 	phys_addr_t start, end;
407 	u64 i;
408 
409 	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &start, &end, NULL) {
410 		unsigned long pfn = clamp_t(unsigned long, PFN_UP(start),
411 					    start_pfn, end_pfn);
412 		unsigned long e_pfn = clamp_t(unsigned long, PFN_DOWN(end),
413 					      start_pfn, end_pfn);
414 		for ( ; pfn < e_pfn; pfn++)
415 			if (pfn_valid(pfn))
416 				free_highmem_page(pfn_to_page(pfn));
417 	}
418 }
419 #else
permanent_kmaps_init(pgd_t * pgd_base)420 static inline void permanent_kmaps_init(pgd_t *pgd_base)
421 {
422 }
423 #endif /* CONFIG_HIGHMEM */
424 
sync_initial_page_table(void)425 void __init sync_initial_page_table(void)
426 {
427 	clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,
428 			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
429 			KERNEL_PGD_PTRS);
430 
431 	/*
432 	 * sync back low identity map too.  It is used for example
433 	 * in the 32-bit EFI stub.
434 	 */
435 	clone_pgd_range(initial_page_table,
436 			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
437 			min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
438 }
439 
native_pagetable_init(void)440 void __init native_pagetable_init(void)
441 {
442 	unsigned long pfn, va;
443 	pgd_t *pgd, *base = swapper_pg_dir;
444 	p4d_t *p4d;
445 	pud_t *pud;
446 	pmd_t *pmd;
447 	pte_t *pte;
448 
449 	/*
450 	 * Remove any mappings which extend past the end of physical
451 	 * memory from the boot time page table.
452 	 * In virtual address space, we should have at least two pages
453 	 * from VMALLOC_END to pkmap or fixmap according to VMALLOC_END
454 	 * definition. And max_low_pfn is set to VMALLOC_END physical
455 	 * address. If initial memory mapping is doing right job, we
456 	 * should have pte used near max_low_pfn or one pmd is not present.
457 	 */
458 	for (pfn = max_low_pfn; pfn < 1<<(32-PAGE_SHIFT); pfn++) {
459 		va = PAGE_OFFSET + (pfn<<PAGE_SHIFT);
460 		pgd = base + pgd_index(va);
461 		if (!pgd_present(*pgd))
462 			break;
463 
464 		p4d = p4d_offset(pgd, va);
465 		pud = pud_offset(p4d, va);
466 		pmd = pmd_offset(pud, va);
467 		if (!pmd_present(*pmd))
468 			break;
469 
470 		/* should not be large page here */
471 		if (pmd_large(*pmd)) {
472 			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",
473 				pfn, pmd, __pa(pmd));
474 			BUG_ON(1);
475 		}
476 
477 		pte = pte_offset_kernel(pmd, va);
478 		if (!pte_present(*pte))
479 			break;
480 
481 		printk(KERN_DEBUG "clearing pte for ram above max_low_pfn: pfn: %lx pmd: %p pmd phys: %lx pte: %p pte phys: %lx\n",
482 				pfn, pmd, __pa(pmd), pte, __pa(pte));
483 		pte_clear(NULL, va, pte);
484 	}
485 	paravirt_alloc_pmd(&init_mm, __pa(base) >> PAGE_SHIFT);
486 	paging_init();
487 }
488 
489 /*
490  * Build a proper pagetable for the kernel mappings.  Up until this
491  * point, we've been running on some set of pagetables constructed by
492  * the boot process.
493  *
494  * If we're booting on native hardware, this will be a pagetable
495  * constructed in arch/x86/kernel/head_32.S.  The root of the
496  * pagetable will be swapper_pg_dir.
497  *
498  * If we're booting paravirtualized under a hypervisor, then there are
499  * more options: we may already be running PAE, and the pagetable may
500  * or may not be based in swapper_pg_dir.  In any case,
501  * paravirt_pagetable_init() will set up swapper_pg_dir
502  * appropriately for the rest of the initialization to work.
503  *
504  * In general, pagetable_init() assumes that the pagetable may already
505  * be partially populated, and so it avoids stomping on any existing
506  * mappings.
507  */
early_ioremap_page_table_range_init(void)508 void __init early_ioremap_page_table_range_init(void)
509 {
510 	pgd_t *pgd_base = swapper_pg_dir;
511 	unsigned long vaddr, end;
512 
513 	/*
514 	 * Fixed mappings, only the page table structure has to be
515 	 * created - mappings will be set by set_fixmap():
516 	 */
517 	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
518 	end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
519 	page_table_range_init(vaddr, end, pgd_base);
520 	early_ioremap_reset();
521 }
522 
pagetable_init(void)523 static void __init pagetable_init(void)
524 {
525 	pgd_t *pgd_base = swapper_pg_dir;
526 
527 	permanent_kmaps_init(pgd_base);
528 }
529 
530 #define DEFAULT_PTE_MASK ~(_PAGE_NX | _PAGE_GLOBAL)
531 /* Bits supported by the hardware: */
532 pteval_t __supported_pte_mask __read_mostly = DEFAULT_PTE_MASK;
533 /* Bits allowed in normal kernel mappings: */
534 pteval_t __default_kernel_pte_mask __read_mostly = DEFAULT_PTE_MASK;
535 EXPORT_SYMBOL_GPL(__supported_pte_mask);
536 /* Used in PAGE_KERNEL_* macros which are reasonably used out-of-tree: */
537 EXPORT_SYMBOL(__default_kernel_pte_mask);
538 
539 /* user-defined highmem size */
540 static unsigned int highmem_pages = -1;
541 
542 /*
543  * highmem=size forces highmem to be exactly 'size' bytes.
544  * This works even on boxes that have no highmem otherwise.
545  * This also works to reduce highmem size on bigger boxes.
546  */
parse_highmem(char * arg)547 static int __init parse_highmem(char *arg)
548 {
549 	if (!arg)
550 		return -EINVAL;
551 
552 	highmem_pages = memparse(arg, &arg) >> PAGE_SHIFT;
553 	return 0;
554 }
555 early_param("highmem", parse_highmem);
556 
557 #define MSG_HIGHMEM_TOO_BIG \
558 	"highmem size (%luMB) is bigger than pages available (%luMB)!\n"
559 
560 #define MSG_LOWMEM_TOO_SMALL \
561 	"highmem size (%luMB) results in <64MB lowmem, ignoring it!\n"
562 /*
563  * All of RAM fits into lowmem - but if user wants highmem
564  * artificially via the highmem=x boot parameter then create
565  * it:
566  */
lowmem_pfn_init(void)567 static void __init lowmem_pfn_init(void)
568 {
569 	/* max_low_pfn is 0, we already have early_res support */
570 	max_low_pfn = max_pfn;
571 
572 	if (highmem_pages == -1)
573 		highmem_pages = 0;
574 #ifdef CONFIG_HIGHMEM
575 	if (highmem_pages >= max_pfn) {
576 		printk(KERN_ERR MSG_HIGHMEM_TOO_BIG,
577 			pages_to_mb(highmem_pages), pages_to_mb(max_pfn));
578 		highmem_pages = 0;
579 	}
580 	if (highmem_pages) {
581 		if (max_low_pfn - highmem_pages < 64*1024*1024/PAGE_SIZE) {
582 			printk(KERN_ERR MSG_LOWMEM_TOO_SMALL,
583 				pages_to_mb(highmem_pages));
584 			highmem_pages = 0;
585 		}
586 		max_low_pfn -= highmem_pages;
587 	}
588 #else
589 	if (highmem_pages)
590 		printk(KERN_ERR "ignoring highmem size on non-highmem kernel!\n");
591 #endif
592 }
593 
594 #define MSG_HIGHMEM_TOO_SMALL \
595 	"only %luMB highmem pages available, ignoring highmem size of %luMB!\n"
596 
597 #define MSG_HIGHMEM_TRIMMED \
598 	"Warning: only 4GB will be used. Use a HIGHMEM64G enabled kernel!\n"
599 /*
600  * We have more RAM than fits into lowmem - we try to put it into
601  * highmem, also taking the highmem=x boot parameter into account:
602  */
highmem_pfn_init(void)603 static void __init highmem_pfn_init(void)
604 {
605 	max_low_pfn = MAXMEM_PFN;
606 
607 	if (highmem_pages == -1)
608 		highmem_pages = max_pfn - MAXMEM_PFN;
609 
610 	if (highmem_pages + MAXMEM_PFN < max_pfn)
611 		max_pfn = MAXMEM_PFN + highmem_pages;
612 
613 	if (highmem_pages + MAXMEM_PFN > max_pfn) {
614 		printk(KERN_WARNING MSG_HIGHMEM_TOO_SMALL,
615 			pages_to_mb(max_pfn - MAXMEM_PFN),
616 			pages_to_mb(highmem_pages));
617 		highmem_pages = 0;
618 	}
619 #ifndef CONFIG_HIGHMEM
620 	/* Maximum memory usable is what is directly addressable */
621 	printk(KERN_WARNING "Warning only %ldMB will be used.\n", MAXMEM>>20);
622 	if (max_pfn > MAX_NONPAE_PFN)
623 		printk(KERN_WARNING "Use a HIGHMEM64G enabled kernel.\n");
624 	else
625 		printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
626 	max_pfn = MAXMEM_PFN;
627 #else /* !CONFIG_HIGHMEM */
628 #ifndef CONFIG_HIGHMEM64G
629 	if (max_pfn > MAX_NONPAE_PFN) {
630 		max_pfn = MAX_NONPAE_PFN;
631 		printk(KERN_WARNING MSG_HIGHMEM_TRIMMED);
632 	}
633 #endif /* !CONFIG_HIGHMEM64G */
634 #endif /* !CONFIG_HIGHMEM */
635 }
636 
637 /*
638  * Determine low and high memory ranges:
639  */
find_low_pfn_range(void)640 void __init find_low_pfn_range(void)
641 {
642 	/* it could update max_pfn */
643 
644 	if (max_pfn <= MAXMEM_PFN)
645 		lowmem_pfn_init();
646 	else
647 		highmem_pfn_init();
648 }
649 
650 #ifndef CONFIG_NUMA
initmem_init(void)651 void __init initmem_init(void)
652 {
653 #ifdef CONFIG_HIGHMEM
654 	highstart_pfn = highend_pfn = max_pfn;
655 	if (max_pfn > max_low_pfn)
656 		highstart_pfn = max_low_pfn;
657 	printk(KERN_NOTICE "%ldMB HIGHMEM available.\n",
658 		pages_to_mb(highend_pfn - highstart_pfn));
659 	high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
660 #else
661 	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
662 #endif
663 
664 	memblock_set_node(0, PHYS_ADDR_MAX, &memblock.memory, 0);
665 
666 #ifdef CONFIG_FLATMEM
667 	max_mapnr = IS_ENABLED(CONFIG_HIGHMEM) ? highend_pfn : max_low_pfn;
668 #endif
669 	__vmalloc_start_set = true;
670 
671 	printk(KERN_NOTICE "%ldMB LOWMEM available.\n",
672 			pages_to_mb(max_low_pfn));
673 
674 	setup_bootmem_allocator();
675 }
676 #endif /* !CONFIG_NUMA */
677 
setup_bootmem_allocator(void)678 void __init setup_bootmem_allocator(void)
679 {
680 	printk(KERN_INFO "  mapped low ram: 0 - %08lx\n",
681 		 max_pfn_mapped<<PAGE_SHIFT);
682 	printk(KERN_INFO "  low ram: 0 - %08lx\n", max_low_pfn<<PAGE_SHIFT);
683 }
684 
685 /*
686  * paging_init() sets up the page tables - note that the first 8MB are
687  * already mapped by head.S.
688  *
689  * This routines also unmaps the page at virtual kernel address 0, so
690  * that we can trap those pesky NULL-reference errors in the kernel.
691  */
paging_init(void)692 void __init paging_init(void)
693 {
694 	pagetable_init();
695 
696 	__flush_tlb_all();
697 
698 	/*
699 	 * NOTE: at this point the bootmem allocator is fully available.
700 	 */
701 	olpc_dt_build_devicetree();
702 	sparse_init();
703 	zone_sizes_init();
704 }
705 
706 /*
707  * Test if the WP bit works in supervisor mode. It isn't supported on 386's
708  * and also on some strange 486's. All 586+'s are OK. This used to involve
709  * black magic jumps to work around some nasty CPU bugs, but fortunately the
710  * switch to using exceptions got rid of all that.
711  */
test_wp_bit(void)712 static void __init test_wp_bit(void)
713 {
714 	char z = 0;
715 
716 	printk(KERN_INFO "Checking if this processor honours the WP bit even in supervisor mode...");
717 
718 	__set_fixmap(FIX_WP_TEST, __pa_symbol(empty_zero_page), PAGE_KERNEL_RO);
719 
720 	if (copy_to_kernel_nofault((char *)fix_to_virt(FIX_WP_TEST), &z, 1)) {
721 		clear_fixmap(FIX_WP_TEST);
722 		printk(KERN_CONT "Ok.\n");
723 		return;
724 	}
725 
726 	printk(KERN_CONT "No.\n");
727 	panic("Linux doesn't support CPUs with broken WP.");
728 }
729 
mem_init(void)730 void __init mem_init(void)
731 {
732 	pci_iommu_alloc();
733 
734 #ifdef CONFIG_FLATMEM
735 	BUG_ON(!mem_map);
736 #endif
737 	/*
738 	 * With CONFIG_DEBUG_PAGEALLOC initialization of highmem pages has to
739 	 * be done before memblock_free_all(). Memblock use free low memory for
740 	 * temporary data (see find_range_array()) and for this purpose can use
741 	 * pages that was already passed to the buddy allocator, hence marked as
742 	 * not accessible in the page tables when compiled with
743 	 * CONFIG_DEBUG_PAGEALLOC. Otherwise order of initialization is not
744 	 * important here.
745 	 */
746 	set_highmem_pages_init();
747 
748 	/* this will put all low memory onto the freelists */
749 	memblock_free_all();
750 
751 	after_bootmem = 1;
752 	x86_init.hyper.init_after_bootmem();
753 
754 	/*
755 	 * Check boundaries twice: Some fundamental inconsistencies can
756 	 * be detected at build time already.
757 	 */
758 #define __FIXADDR_TOP (-PAGE_SIZE)
759 #ifdef CONFIG_HIGHMEM
760 	BUILD_BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE	> FIXADDR_START);
761 	BUILD_BUG_ON(VMALLOC_END			> PKMAP_BASE);
762 #endif
763 #define high_memory (-128UL << 20)
764 	BUILD_BUG_ON(VMALLOC_START			>= VMALLOC_END);
765 #undef high_memory
766 #undef __FIXADDR_TOP
767 
768 #ifdef CONFIG_HIGHMEM
769 	BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE	> FIXADDR_START);
770 	BUG_ON(VMALLOC_END				> PKMAP_BASE);
771 #endif
772 	BUG_ON(VMALLOC_START				>= VMALLOC_END);
773 	BUG_ON((unsigned long)high_memory		> VMALLOC_START);
774 
775 	test_wp_bit();
776 }
777 
778 int kernel_set_to_readonly __read_mostly;
779 
mark_nxdata_nx(void)780 static void mark_nxdata_nx(void)
781 {
782 	/*
783 	 * When this called, init has already been executed and released,
784 	 * so everything past _etext should be NX.
785 	 */
786 	unsigned long start = PFN_ALIGN(_etext);
787 	/*
788 	 * This comes from is_x86_32_kernel_text upper limit. Also HPAGE where used:
789 	 */
790 	unsigned long size = (((unsigned long)__init_end + HPAGE_SIZE) & HPAGE_MASK) - start;
791 
792 	if (__supported_pte_mask & _PAGE_NX)
793 		printk(KERN_INFO "NX-protecting the kernel data: %luk\n", size >> 10);
794 	set_memory_nx(start, size >> PAGE_SHIFT);
795 }
796 
mark_rodata_ro(void)797 void mark_rodata_ro(void)
798 {
799 	unsigned long start = PFN_ALIGN(_text);
800 	unsigned long size = (unsigned long)__end_rodata - start;
801 
802 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
803 	pr_info("Write protecting kernel text and read-only data: %luk\n",
804 		size >> 10);
805 
806 	kernel_set_to_readonly = 1;
807 
808 #ifdef CONFIG_CPA_DEBUG
809 	pr_info("Testing CPA: Reverting %lx-%lx\n", start, start + size);
810 	set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
811 
812 	pr_info("Testing CPA: write protecting again\n");
813 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
814 #endif
815 	mark_nxdata_nx();
816 	if (__supported_pte_mask & _PAGE_NX)
817 		debug_checkwx();
818 }
819