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1  // SPDX-License-Identifier: GPL-2.0-or-later
2  /*
3   * This file contains the routines setting up the linux page tables.
4   *  -- paulus
5   *
6   *  Derived from arch/ppc/mm/init.c:
7   *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
8   *
9   *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
10   *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
11   *    Copyright (C) 1996 Paul Mackerras
12   *
13   *  Derived from "arch/i386/mm/init.c"
14   *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
15   */
16  
17  #include <linux/kernel.h>
18  #include <linux/module.h>
19  #include <linux/types.h>
20  #include <linux/mm.h>
21  #include <linux/vmalloc.h>
22  #include <linux/init.h>
23  #include <linux/highmem.h>
24  #include <linux/memblock.h>
25  #include <linux/slab.h>
26  
27  #include <asm/pgalloc.h>
28  #include <asm/fixmap.h>
29  #include <asm/setup.h>
30  #include <asm/sections.h>
31  #include <asm/early_ioremap.h>
32  
33  #include <mm/mmu_decl.h>
34  
35  extern char etext[], _stext[], _sinittext[], _einittext[];
36  
37  static u8 early_fixmap_pagetable[FIXMAP_PTE_SIZE] __page_aligned_data;
38  
early_ioremap_init(void)39  notrace void __init early_ioremap_init(void)
40  {
41  	unsigned long addr = ALIGN_DOWN(FIXADDR_START, PGDIR_SIZE);
42  	pte_t *ptep = (pte_t *)early_fixmap_pagetable;
43  	pmd_t *pmdp = pmd_off_k(addr);
44  
45  	for (; (s32)(FIXADDR_TOP - addr) > 0;
46  	     addr += PGDIR_SIZE, ptep += PTRS_PER_PTE, pmdp++)
47  		pmd_populate_kernel(&init_mm, pmdp, ptep);
48  
49  	early_ioremap_setup();
50  }
51  
early_alloc_pgtable(unsigned long size)52  static void __init *early_alloc_pgtable(unsigned long size)
53  {
54  	void *ptr = memblock_alloc(size, size);
55  
56  	if (!ptr)
57  		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
58  		      __func__, size, size);
59  
60  	return ptr;
61  }
62  
early_pte_alloc_kernel(pmd_t * pmdp,unsigned long va)63  pte_t __init *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
64  {
65  	if (pmd_none(*pmdp)) {
66  		pte_t *ptep = early_alloc_pgtable(PTE_FRAG_SIZE);
67  
68  		pmd_populate_kernel(&init_mm, pmdp, ptep);
69  	}
70  	return pte_offset_kernel(pmdp, va);
71  }
72  
73  
map_kernel_page(unsigned long va,phys_addr_t pa,pgprot_t prot)74  int __ref map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
75  {
76  	pmd_t *pd;
77  	pte_t *pg;
78  	int err = -ENOMEM;
79  
80  	/* Use upper 10 bits of VA to index the first level map */
81  	pd = pmd_off_k(va);
82  	/* Use middle 10 bits of VA to index the second-level map */
83  	if (likely(slab_is_available()))
84  		pg = pte_alloc_kernel(pd, va);
85  	else
86  		pg = early_pte_alloc_kernel(pd, va);
87  	if (pg != 0) {
88  		err = 0;
89  		/* The PTE should never be already set nor present in the
90  		 * hash table
91  		 */
92  		BUG_ON((pte_present(*pg) | pte_hashpte(*pg)) && pgprot_val(prot));
93  		set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, prot));
94  	}
95  	smp_wmb();
96  	return err;
97  }
98  
99  /*
100   * Map in a chunk of physical memory starting at start.
101   */
__mapin_ram_chunk(unsigned long offset,unsigned long top)102  static void __init __mapin_ram_chunk(unsigned long offset, unsigned long top)
103  {
104  	unsigned long v, s;
105  	phys_addr_t p;
106  	int ktext;
107  
108  	s = offset;
109  	v = PAGE_OFFSET + s;
110  	p = memstart_addr + s;
111  	for (; s < top; s += PAGE_SIZE) {
112  		ktext = ((char *)v >= _stext && (char *)v < etext) ||
113  			((char *)v >= _sinittext && (char *)v < _einittext);
114  		map_kernel_page(v, p, ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL);
115  #ifdef CONFIG_PPC_BOOK3S_32
116  		if (ktext)
117  			hash_preload(&init_mm, v);
118  #endif
119  		v += PAGE_SIZE;
120  		p += PAGE_SIZE;
121  	}
122  }
123  
mapin_ram(void)124  void __init mapin_ram(void)
125  {
126  	phys_addr_t base, end;
127  	u64 i;
128  
129  	for_each_mem_range(i, &base, &end) {
130  		phys_addr_t top = min(end, total_lowmem);
131  
132  		if (base >= top)
133  			continue;
134  		base = mmu_mapin_ram(base, top);
135  		__mapin_ram_chunk(base, top);
136  	}
137  }
138  
__change_page_attr_noflush(struct page * page,pgprot_t prot)139  static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
140  {
141  	pte_t *kpte;
142  	unsigned long address;
143  
144  	BUG_ON(PageHighMem(page));
145  	address = (unsigned long)page_address(page);
146  
147  	if (v_block_mapped(address))
148  		return 0;
149  	kpte = virt_to_kpte(address);
150  	if (!kpte)
151  		return -EINVAL;
152  	__set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0);
153  
154  	return 0;
155  }
156  
157  /*
158   * Change the page attributes of an page in the linear mapping.
159   *
160   * THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY
161   */
change_page_attr(struct page * page,int numpages,pgprot_t prot)162  static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
163  {
164  	int i, err = 0;
165  	unsigned long flags;
166  	struct page *start = page;
167  
168  	local_irq_save(flags);
169  	for (i = 0; i < numpages; i++, page++) {
170  		err = __change_page_attr_noflush(page, prot);
171  		if (err)
172  			break;
173  	}
174  	wmb();
175  	local_irq_restore(flags);
176  	flush_tlb_kernel_range((unsigned long)page_address(start),
177  			       (unsigned long)page_address(page));
178  	return err;
179  }
180  
mark_initmem_nx(void)181  void mark_initmem_nx(void)
182  {
183  	struct page *page = virt_to_page(_sinittext);
184  	unsigned long numpages = PFN_UP((unsigned long)_einittext) -
185  				 PFN_DOWN((unsigned long)_sinittext);
186  
187  	if (v_block_mapped((unsigned long)_sinittext))
188  		mmu_mark_initmem_nx();
189  	else
190  		change_page_attr(page, numpages, PAGE_KERNEL);
191  }
192  
193  #ifdef CONFIG_STRICT_KERNEL_RWX
mark_rodata_ro(void)194  void mark_rodata_ro(void)
195  {
196  	struct page *page;
197  	unsigned long numpages;
198  
199  	if (v_block_mapped((unsigned long)_stext + 1)) {
200  		mmu_mark_rodata_ro();
201  		ptdump_check_wx();
202  		return;
203  	}
204  
205  	page = virt_to_page(_stext);
206  	numpages = PFN_UP((unsigned long)_etext) -
207  		   PFN_DOWN((unsigned long)_stext);
208  
209  	change_page_attr(page, numpages, PAGE_KERNEL_ROX);
210  	/*
211  	 * mark .rodata as read only. Use __init_begin rather than __end_rodata
212  	 * to cover NOTES and EXCEPTION_TABLE.
213  	 */
214  	page = virt_to_page(__start_rodata);
215  	numpages = PFN_UP((unsigned long)__init_begin) -
216  		   PFN_DOWN((unsigned long)__start_rodata);
217  
218  	change_page_attr(page, numpages, PAGE_KERNEL_RO);
219  
220  	// mark_initmem_nx() should have already run by now
221  	ptdump_check_wx();
222  }
223  #endif
224  
225  #ifdef CONFIG_DEBUG_PAGEALLOC
__kernel_map_pages(struct page * page,int numpages,int enable)226  void __kernel_map_pages(struct page *page, int numpages, int enable)
227  {
228  	if (PageHighMem(page))
229  		return;
230  
231  	change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
232  }
233  #endif /* CONFIG_DEBUG_PAGEALLOC */
234