1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Initialize MMU support.
  4 *
  5 * Copyright (C) 1998-2003 Hewlett-Packard Co
  6 *	David Mosberger-Tang <davidm@hpl.hp.com>
  7 */
  8#include <linux/kernel.h>
  9#include <linux/init.h>
 10
 11#include <linux/bootmem.h>
 12#include <linux/efi.h>
 13#include <linux/elf.h>
 14#include <linux/memblock.h>
 15#include <linux/mm.h>
 16#include <linux/sched/signal.h>
 17#include <linux/mmzone.h>
 18#include <linux/module.h>
 19#include <linux/personality.h>
 20#include <linux/reboot.h>
 21#include <linux/slab.h>
 22#include <linux/swap.h>
 23#include <linux/proc_fs.h>
 24#include <linux/bitops.h>
 25#include <linux/kexec.h>
 26
 27#include <asm/dma.h>
 28#include <asm/io.h>
 29#include <asm/machvec.h>
 30#include <asm/numa.h>
 31#include <asm/patch.h>
 32#include <asm/pgalloc.h>
 33#include <asm/sal.h>
 34#include <asm/sections.h>
 35#include <asm/tlb.h>
 36#include <linux/uaccess.h>
 37#include <asm/unistd.h>
 38#include <asm/mca.h>
 39
 40extern void ia64_tlb_init (void);
 41
 42unsigned long MAX_DMA_ADDRESS = PAGE_OFFSET + 0x100000000UL;
 43
 44#ifdef CONFIG_VIRTUAL_MEM_MAP
 45unsigned long VMALLOC_END = VMALLOC_END_INIT;
 46EXPORT_SYMBOL(VMALLOC_END);
 47struct page *vmem_map;
 48EXPORT_SYMBOL(vmem_map);
 49#endif
 50
 51struct page *zero_page_memmap_ptr;	/* map entry for zero page */
 52EXPORT_SYMBOL(zero_page_memmap_ptr);
 53
 54void
 55__ia64_sync_icache_dcache (pte_t pte)
 56{
 57	unsigned long addr;
 58	struct page *page;
 59
 60	page = pte_page(pte);
 61	addr = (unsigned long) page_address(page);
 62
 63	if (test_bit(PG_arch_1, &page->flags))
 64		return;				/* i-cache is already coherent with d-cache */
 65
 66	flush_icache_range(addr, addr + (PAGE_SIZE << compound_order(page)));
 67	set_bit(PG_arch_1, &page->flags);	/* mark page as clean */
 68}
 69
 70/*
 71 * Since DMA is i-cache coherent, any (complete) pages that were written via
 72 * DMA can be marked as "clean" so that lazy_mmu_prot_update() doesn't have to
 73 * flush them when they get mapped into an executable vm-area.
 74 */
 75void
 76dma_mark_clean(void *addr, size_t size)
 77{
 78	unsigned long pg_addr, end;
 79
 80	pg_addr = PAGE_ALIGN((unsigned long) addr);
 81	end = (unsigned long) addr + size;
 82	while (pg_addr + PAGE_SIZE <= end) {
 83		struct page *page = virt_to_page(pg_addr);
 84		set_bit(PG_arch_1, &page->flags);
 85		pg_addr += PAGE_SIZE;
 86	}
 87}
 88
 89inline void
 90ia64_set_rbs_bot (void)
 91{
 92	unsigned long stack_size = rlimit_max(RLIMIT_STACK) & -16;
 93
 94	if (stack_size > MAX_USER_STACK_SIZE)
 95		stack_size = MAX_USER_STACK_SIZE;
 96	current->thread.rbs_bot = PAGE_ALIGN(current->mm->start_stack - stack_size);
 97}
 98
 99/*
100 * This performs some platform-dependent address space initialization.
101 * On IA-64, we want to setup the VM area for the register backing
102 * store (which grows upwards) and install the gateway page which is
103 * used for signal trampolines, etc.
104 */
105void
106ia64_init_addr_space (void)
107{
108	struct vm_area_struct *vma;
109
110	ia64_set_rbs_bot();
111
112	/*
113	 * If we're out of memory and kmem_cache_alloc() returns NULL, we simply ignore
114	 * the problem.  When the process attempts to write to the register backing store
115	 * for the first time, it will get a SEGFAULT in this case.
116	 */
117	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
118	if (vma) {
119		INIT_LIST_HEAD(&vma->anon_vma_chain);
120		vma->vm_mm = current->mm;
121		vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
122		vma->vm_end = vma->vm_start + PAGE_SIZE;
123		vma->vm_flags = VM_DATA_DEFAULT_FLAGS|VM_GROWSUP|VM_ACCOUNT;
124		vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
125		down_write(&current->mm->mmap_sem);
126		if (insert_vm_struct(current->mm, vma)) {
127			up_write(&current->mm->mmap_sem);
128			kmem_cache_free(vm_area_cachep, vma);
129			return;
130		}
131		up_write(&current->mm->mmap_sem);
132	}
133
134	/* map NaT-page at address zero to speed up speculative dereferencing of NULL: */
135	if (!(current->personality & MMAP_PAGE_ZERO)) {
136		vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
137		if (vma) {
138			INIT_LIST_HEAD(&vma->anon_vma_chain);
139			vma->vm_mm = current->mm;
140			vma->vm_end = PAGE_SIZE;
141			vma->vm_page_prot = __pgprot(pgprot_val(PAGE_READONLY) | _PAGE_MA_NAT);
142			vma->vm_flags = VM_READ | VM_MAYREAD | VM_IO |
143					VM_DONTEXPAND | VM_DONTDUMP;
144			down_write(&current->mm->mmap_sem);
145			if (insert_vm_struct(current->mm, vma)) {
146				up_write(&current->mm->mmap_sem);
147				kmem_cache_free(vm_area_cachep, vma);
148				return;
149			}
150			up_write(&current->mm->mmap_sem);
151		}
152	}
153}
154
155void
156free_initmem (void)
157{
158	free_reserved_area(ia64_imva(__init_begin), ia64_imva(__init_end),
159			   -1, "unused kernel");
160}
161
162void __init
163free_initrd_mem (unsigned long start, unsigned long end)
164{
165	/*
166	 * EFI uses 4KB pages while the kernel can use 4KB or bigger.
167	 * Thus EFI and the kernel may have different page sizes. It is
168	 * therefore possible to have the initrd share the same page as
169	 * the end of the kernel (given current setup).
170	 *
171	 * To avoid freeing/using the wrong page (kernel sized) we:
172	 *	- align up the beginning of initrd
173	 *	- align down the end of initrd
174	 *
175	 *  |             |
176	 *  |=============| a000
177	 *  |             |
178	 *  |             |
179	 *  |             | 9000
180	 *  |/////////////|
181	 *  |/////////////|
182	 *  |=============| 8000
183	 *  |///INITRD////|
184	 *  |/////////////|
185	 *  |/////////////| 7000
186	 *  |             |
187	 *  |KKKKKKKKKKKKK|
188	 *  |=============| 6000
189	 *  |KKKKKKKKKKKKK|
190	 *  |KKKKKKKKKKKKK|
191	 *  K=kernel using 8KB pages
192	 *
193	 * In this example, we must free page 8000 ONLY. So we must align up
194	 * initrd_start and keep initrd_end as is.
195	 */
196	start = PAGE_ALIGN(start);
197	end = end & PAGE_MASK;
198
199	if (start < end)
200		printk(KERN_INFO "Freeing initrd memory: %ldkB freed\n", (end - start) >> 10);
201
202	for (; start < end; start += PAGE_SIZE) {
203		if (!virt_addr_valid(start))
204			continue;
205		free_reserved_page(virt_to_page(start));
206	}
207}
208
209/*
210 * This installs a clean page in the kernel's page table.
211 */
212static struct page * __init
213put_kernel_page (struct page *page, unsigned long address, pgprot_t pgprot)
214{
215	pgd_t *pgd;
216	pud_t *pud;
217	pmd_t *pmd;
218	pte_t *pte;
219
220	pgd = pgd_offset_k(address);		/* note: this is NOT pgd_offset()! */
221
222	{
223		pud = pud_alloc(&init_mm, pgd, address);
224		if (!pud)
225			goto out;
226		pmd = pmd_alloc(&init_mm, pud, address);
227		if (!pmd)
228			goto out;
229		pte = pte_alloc_kernel(pmd, address);
230		if (!pte)
231			goto out;
232		if (!pte_none(*pte))
233			goto out;
234		set_pte(pte, mk_pte(page, pgprot));
235	}
236  out:
237	/* no need for flush_tlb */
238	return page;
239}
240
241static void __init
242setup_gate (void)
243{
244	struct page *page;
245
246	/*
247	 * Map the gate page twice: once read-only to export the ELF
248	 * headers etc. and once execute-only page to enable
249	 * privilege-promotion via "epc":
250	 */
251	page = virt_to_page(ia64_imva(__start_gate_section));
252	put_kernel_page(page, GATE_ADDR, PAGE_READONLY);
253#ifdef HAVE_BUGGY_SEGREL
254	page = virt_to_page(ia64_imva(__start_gate_section + PAGE_SIZE));
255	put_kernel_page(page, GATE_ADDR + PAGE_SIZE, PAGE_GATE);
256#else
257	put_kernel_page(page, GATE_ADDR + PERCPU_PAGE_SIZE, PAGE_GATE);
258	/* Fill in the holes (if any) with read-only zero pages: */
259	{
260		unsigned long addr;
261
262		for (addr = GATE_ADDR + PAGE_SIZE;
263		     addr < GATE_ADDR + PERCPU_PAGE_SIZE;
264		     addr += PAGE_SIZE)
265		{
266			put_kernel_page(ZERO_PAGE(0), addr,
267					PAGE_READONLY);
268			put_kernel_page(ZERO_PAGE(0), addr + PERCPU_PAGE_SIZE,
269					PAGE_READONLY);
270		}
271	}
272#endif
273	ia64_patch_gate();
274}
275
276static struct vm_area_struct gate_vma;
277
278static int __init gate_vma_init(void)
279{
280	gate_vma.vm_mm = NULL;
281	gate_vma.vm_start = FIXADDR_USER_START;
282	gate_vma.vm_end = FIXADDR_USER_END;
283	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
284	gate_vma.vm_page_prot = __P101;
285
286	return 0;
287}
288__initcall(gate_vma_init);
289
290struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
291{
292	return &gate_vma;
293}
294
295int in_gate_area_no_mm(unsigned long addr)
296{
297	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
298		return 1;
299	return 0;
300}
301
302int in_gate_area(struct mm_struct *mm, unsigned long addr)
303{
304	return in_gate_area_no_mm(addr);
305}
306
307void ia64_mmu_init(void *my_cpu_data)
308{
309	unsigned long pta, impl_va_bits;
310	extern void tlb_init(void);
311
312#ifdef CONFIG_DISABLE_VHPT
313#	define VHPT_ENABLE_BIT	0
314#else
315#	define VHPT_ENABLE_BIT	1
316#endif
317
318	/*
319	 * Check if the virtually mapped linear page table (VMLPT) overlaps with a mapped
320	 * address space.  The IA-64 architecture guarantees that at least 50 bits of
321	 * virtual address space are implemented but if we pick a large enough page size
322	 * (e.g., 64KB), the mapped address space is big enough that it will overlap with
323	 * VMLPT.  I assume that once we run on machines big enough to warrant 64KB pages,
324	 * IMPL_VA_MSB will be significantly bigger, so this is unlikely to become a
325	 * problem in practice.  Alternatively, we could truncate the top of the mapped
326	 * address space to not permit mappings that would overlap with the VMLPT.
327	 * --davidm 00/12/06
328	 */
329#	define pte_bits			3
330#	define mapped_space_bits	(3*(PAGE_SHIFT - pte_bits) + PAGE_SHIFT)
331	/*
332	 * The virtual page table has to cover the entire implemented address space within
333	 * a region even though not all of this space may be mappable.  The reason for
334	 * this is that the Access bit and Dirty bit fault handlers perform
335	 * non-speculative accesses to the virtual page table, so the address range of the
336	 * virtual page table itself needs to be covered by virtual page table.
337	 */
338#	define vmlpt_bits		(impl_va_bits - PAGE_SHIFT + pte_bits)
339#	define POW2(n)			(1ULL << (n))
340
341	impl_va_bits = ffz(~(local_cpu_data->unimpl_va_mask | (7UL << 61)));
342
343	if (impl_va_bits < 51 || impl_va_bits > 61)
344		panic("CPU has bogus IMPL_VA_MSB value of %lu!\n", impl_va_bits - 1);
345	/*
346	 * mapped_space_bits - PAGE_SHIFT is the total number of ptes we need,
347	 * which must fit into "vmlpt_bits - pte_bits" slots. Second half of
348	 * the test makes sure that our mapped space doesn't overlap the
349	 * unimplemented hole in the middle of the region.
350	 */
351	if ((mapped_space_bits - PAGE_SHIFT > vmlpt_bits - pte_bits) ||
352	    (mapped_space_bits > impl_va_bits - 1))
353		panic("Cannot build a big enough virtual-linear page table"
354		      " to cover mapped address space.\n"
355		      " Try using a smaller page size.\n");
356
357
358	/* place the VMLPT at the end of each page-table mapped region: */
359	pta = POW2(61) - POW2(vmlpt_bits);
360
361	/*
362	 * Set the (virtually mapped linear) page table address.  Bit
363	 * 8 selects between the short and long format, bits 2-7 the
364	 * size of the table, and bit 0 whether the VHPT walker is
365	 * enabled.
366	 */
367	ia64_set_pta(pta | (0 << 8) | (vmlpt_bits << 2) | VHPT_ENABLE_BIT);
368
369	ia64_tlb_init();
370
371#ifdef	CONFIG_HUGETLB_PAGE
372	ia64_set_rr(HPAGE_REGION_BASE, HPAGE_SHIFT << 2);
373	ia64_srlz_d();
374#endif
375}
376
377#ifdef CONFIG_VIRTUAL_MEM_MAP
378int vmemmap_find_next_valid_pfn(int node, int i)
379{
380	unsigned long end_address, hole_next_pfn;
381	unsigned long stop_address;
382	pg_data_t *pgdat = NODE_DATA(node);
383
384	end_address = (unsigned long) &vmem_map[pgdat->node_start_pfn + i];
385	end_address = PAGE_ALIGN(end_address);
386	stop_address = (unsigned long) &vmem_map[pgdat_end_pfn(pgdat)];
387
388	do {
389		pgd_t *pgd;
390		pud_t *pud;
391		pmd_t *pmd;
392		pte_t *pte;
393
394		pgd = pgd_offset_k(end_address);
395		if (pgd_none(*pgd)) {
396			end_address += PGDIR_SIZE;
397			continue;
398		}
399
400		pud = pud_offset(pgd, end_address);
401		if (pud_none(*pud)) {
402			end_address += PUD_SIZE;
403			continue;
404		}
405
406		pmd = pmd_offset(pud, end_address);
407		if (pmd_none(*pmd)) {
408			end_address += PMD_SIZE;
409			continue;
410		}
411
412		pte = pte_offset_kernel(pmd, end_address);
413retry_pte:
414		if (pte_none(*pte)) {
415			end_address += PAGE_SIZE;
416			pte++;
417			if ((end_address < stop_address) &&
418			    (end_address != ALIGN(end_address, 1UL << PMD_SHIFT)))
419				goto retry_pte;
420			continue;
421		}
422		/* Found next valid vmem_map page */
423		break;
424	} while (end_address < stop_address);
425
426	end_address = min(end_address, stop_address);
427	end_address = end_address - (unsigned long) vmem_map + sizeof(struct page) - 1;
428	hole_next_pfn = end_address / sizeof(struct page);
429	return hole_next_pfn - pgdat->node_start_pfn;
430}
431
432int __init create_mem_map_page_table(u64 start, u64 end, void *arg)
433{
434	unsigned long address, start_page, end_page;
435	struct page *map_start, *map_end;
436	int node;
437	pgd_t *pgd;
438	pud_t *pud;
439	pmd_t *pmd;
440	pte_t *pte;
441
442	map_start = vmem_map + (__pa(start) >> PAGE_SHIFT);
443	map_end   = vmem_map + (__pa(end) >> PAGE_SHIFT);
444
445	start_page = (unsigned long) map_start & PAGE_MASK;
446	end_page = PAGE_ALIGN((unsigned long) map_end);
447	node = paddr_to_nid(__pa(start));
448
449	for (address = start_page; address < end_page; address += PAGE_SIZE) {
450		pgd = pgd_offset_k(address);
451		if (pgd_none(*pgd))
452			pgd_populate(&init_mm, pgd, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
453		pud = pud_offset(pgd, address);
454
455		if (pud_none(*pud))
456			pud_populate(&init_mm, pud, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
457		pmd = pmd_offset(pud, address);
458
459		if (pmd_none(*pmd))
460			pmd_populate_kernel(&init_mm, pmd, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
461		pte = pte_offset_kernel(pmd, address);
462
463		if (pte_none(*pte))
464			set_pte(pte, pfn_pte(__pa(alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE)) >> PAGE_SHIFT,
465					     PAGE_KERNEL));
466	}
467	return 0;
468}
469
470struct memmap_init_callback_data {
471	struct page *start;
472	struct page *end;
473	int nid;
474	unsigned long zone;
475};
476
477static int __meminit
478virtual_memmap_init(u64 start, u64 end, void *arg)
479{
480	struct memmap_init_callback_data *args;
481	struct page *map_start, *map_end;
482
483	args = (struct memmap_init_callback_data *) arg;
484	map_start = vmem_map + (__pa(start) >> PAGE_SHIFT);
485	map_end   = vmem_map + (__pa(end) >> PAGE_SHIFT);
486
487	if (map_start < args->start)
488		map_start = args->start;
489	if (map_end > args->end)
490		map_end = args->end;
491
492	/*
493	 * We have to initialize "out of bounds" struct page elements that fit completely
494	 * on the same pages that were allocated for the "in bounds" elements because they
495	 * may be referenced later (and found to be "reserved").
496	 */
497	map_start -= ((unsigned long) map_start & (PAGE_SIZE - 1)) / sizeof(struct page);
498	map_end += ((PAGE_ALIGN((unsigned long) map_end) - (unsigned long) map_end)
499		    / sizeof(struct page));
500
501	if (map_start < map_end)
502		memmap_init_zone((unsigned long)(map_end - map_start),
503				 args->nid, args->zone, page_to_pfn(map_start),
504				 MEMMAP_EARLY, NULL);
505	return 0;
506}
507
508void __meminit
509memmap_init (unsigned long size, int nid, unsigned long zone,
510	     unsigned long start_pfn)
511{
512	if (!vmem_map) {
513		memmap_init_zone(size, nid, zone, start_pfn, MEMMAP_EARLY,
514				NULL);
515	} else {
516		struct page *start;
517		struct memmap_init_callback_data args;
518
519		start = pfn_to_page(start_pfn);
520		args.start = start;
521		args.end = start + size;
522		args.nid = nid;
523		args.zone = zone;
524
525		efi_memmap_walk(virtual_memmap_init, &args);
526	}
527}
528
529int
530ia64_pfn_valid (unsigned long pfn)
531{
532	char byte;
533	struct page *pg = pfn_to_page(pfn);
534
535	return     (__get_user(byte, (char __user *) pg) == 0)
536		&& ((((u64)pg & PAGE_MASK) == (((u64)(pg + 1) - 1) & PAGE_MASK))
537			|| (__get_user(byte, (char __user *) (pg + 1) - 1) == 0));
538}
539EXPORT_SYMBOL(ia64_pfn_valid);
540
541int __init find_largest_hole(u64 start, u64 end, void *arg)
542{
543	u64 *max_gap = arg;
544
545	static u64 last_end = PAGE_OFFSET;
546
547	/* NOTE: this algorithm assumes efi memmap table is ordered */
548
549	if (*max_gap < (start - last_end))
550		*max_gap = start - last_end;
551	last_end = end;
552	return 0;
553}
554
555#endif /* CONFIG_VIRTUAL_MEM_MAP */
556
557int __init register_active_ranges(u64 start, u64 len, int nid)
558{
559	u64 end = start + len;
560
561#ifdef CONFIG_KEXEC
562	if (start > crashk_res.start && start < crashk_res.end)
563		start = crashk_res.end;
564	if (end > crashk_res.start && end < crashk_res.end)
565		end = crashk_res.start;
566#endif
567
568	if (start < end)
569		memblock_add_node(__pa(start), end - start, nid);
570	return 0;
571}
572
573int
574find_max_min_low_pfn (u64 start, u64 end, void *arg)
575{
576	unsigned long pfn_start, pfn_end;
577#ifdef CONFIG_FLATMEM
578	pfn_start = (PAGE_ALIGN(__pa(start))) >> PAGE_SHIFT;
579	pfn_end = (PAGE_ALIGN(__pa(end - 1))) >> PAGE_SHIFT;
580#else
581	pfn_start = GRANULEROUNDDOWN(__pa(start)) >> PAGE_SHIFT;
582	pfn_end = GRANULEROUNDUP(__pa(end - 1)) >> PAGE_SHIFT;
583#endif
584	min_low_pfn = min(min_low_pfn, pfn_start);
585	max_low_pfn = max(max_low_pfn, pfn_end);
586	return 0;
587}
588
589/*
590 * Boot command-line option "nolwsys" can be used to disable the use of any light-weight
591 * system call handler.  When this option is in effect, all fsyscalls will end up bubbling
592 * down into the kernel and calling the normal (heavy-weight) syscall handler.  This is
593 * useful for performance testing, but conceivably could also come in handy for debugging
594 * purposes.
595 */
596
597static int nolwsys __initdata;
598
599static int __init
600nolwsys_setup (char *s)
601{
602	nolwsys = 1;
603	return 1;
604}
605
606__setup("nolwsys", nolwsys_setup);
607
608void __init
609mem_init (void)
610{
611	int i;
612
613	BUG_ON(PTRS_PER_PGD * sizeof(pgd_t) != PAGE_SIZE);
614	BUG_ON(PTRS_PER_PMD * sizeof(pmd_t) != PAGE_SIZE);
615	BUG_ON(PTRS_PER_PTE * sizeof(pte_t) != PAGE_SIZE);
616
617#ifdef CONFIG_PCI
618	/*
619	 * This needs to be called _after_ the command line has been parsed but _before_
620	 * any drivers that may need the PCI DMA interface are initialized or bootmem has
621	 * been freed.
622	 */
623	platform_dma_init();
624#endif
625
626#ifdef CONFIG_FLATMEM
627	BUG_ON(!mem_map);
628#endif
629
630	set_max_mapnr(max_low_pfn);
631	high_memory = __va(max_low_pfn * PAGE_SIZE);
632	free_all_bootmem();
633	mem_init_print_info(NULL);
634
635	/*
636	 * For fsyscall entrpoints with no light-weight handler, use the ordinary
637	 * (heavy-weight) handler, but mark it by setting bit 0, so the fsyscall entry
638	 * code can tell them apart.
639	 */
640	for (i = 0; i < NR_syscalls; ++i) {
641		extern unsigned long fsyscall_table[NR_syscalls];
642		extern unsigned long sys_call_table[NR_syscalls];
643
644		if (!fsyscall_table[i] || nolwsys)
645			fsyscall_table[i] = sys_call_table[i] | 1;
646	}
647	setup_gate();
648}
649
650#ifdef CONFIG_MEMORY_HOTPLUG
651int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
652		bool want_memblock)
653{
654	unsigned long start_pfn = start >> PAGE_SHIFT;
655	unsigned long nr_pages = size >> PAGE_SHIFT;
656	int ret;
657
658	ret = __add_pages(nid, start_pfn, nr_pages, altmap, want_memblock);
659	if (ret)
660		printk("%s: Problem encountered in __add_pages() as ret=%d\n",
661		       __func__,  ret);
662
663	return ret;
664}
665
666#ifdef CONFIG_MEMORY_HOTREMOVE
667int arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
668{
669	unsigned long start_pfn = start >> PAGE_SHIFT;
670	unsigned long nr_pages = size >> PAGE_SHIFT;
671	struct zone *zone;
672	int ret;
673
674	zone = page_zone(pfn_to_page(start_pfn));
675	ret = __remove_pages(zone, start_pfn, nr_pages, altmap);
676	if (ret)
677		pr_warn("%s: Problem encountered in __remove_pages() as"
678			" ret=%d\n", __func__,  ret);
679
680	return ret;
681}
682#endif
683#endif