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/pgtable.h> 28 #include <asm/pgalloc.h> 29 #include <asm/fixmap.h> 30 #include <asm/setup.h> 31 #include <asm/sections.h> 32 33 #include <mm/mmu_decl.h> 34 35 extern char etext[], _stext[], _sinittext[], _einittext[]; 36 37 static void __init *early_alloc_pgtable(unsigned long size) 38 { 39 void *ptr = memblock_alloc(size, size); 40 41 if (!ptr) 42 panic("%s: Failed to allocate %lu bytes align=0x%lx\n", 43 __func__, size, size); 44 45 return ptr; 46 } 47 48 static pte_t __init *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va) 49 { 50 if (pmd_none(*pmdp)) { 51 pte_t *ptep = early_alloc_pgtable(PTE_FRAG_SIZE); 52 53 pmd_populate_kernel(&init_mm, pmdp, ptep); 54 } 55 return pte_offset_kernel(pmdp, va); 56 } 57 58 59 int __ref map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot) 60 { 61 pmd_t *pd; 62 pte_t *pg; 63 int err = -ENOMEM; 64 65 /* Use upper 10 bits of VA to index the first level map */ 66 pd = pmd_offset(pud_offset(pgd_offset_k(va), va), va); 67 /* Use middle 10 bits of VA to index the second-level map */ 68 if (likely(slab_is_available())) 69 pg = pte_alloc_kernel(pd, va); 70 else 71 pg = early_pte_alloc_kernel(pd, va); 72 if (pg != 0) { 73 err = 0; 74 /* The PTE should never be already set nor present in the 75 * hash table 76 */ 77 BUG_ON((pte_present(*pg) | pte_hashpte(*pg)) && pgprot_val(prot)); 78 set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, prot)); 79 } 80 smp_wmb(); 81 return err; 82 } 83 84 /* 85 * Map in a chunk of physical memory starting at start. 86 */ 87 static void __init __mapin_ram_chunk(unsigned long offset, unsigned long top) 88 { 89 unsigned long v, s; 90 phys_addr_t p; 91 int ktext; 92 93 s = offset; 94 v = PAGE_OFFSET + s; 95 p = memstart_addr + s; 96 for (; s < top; s += PAGE_SIZE) { 97 ktext = ((char *)v >= _stext && (char *)v < etext) || 98 ((char *)v >= _sinittext && (char *)v < _einittext); 99 map_kernel_page(v, p, ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL); 100 #ifdef CONFIG_PPC_BOOK3S_32 101 if (ktext) 102 hash_preload(&init_mm, v); 103 #endif 104 v += PAGE_SIZE; 105 p += PAGE_SIZE; 106 } 107 } 108 109 void __init mapin_ram(void) 110 { 111 struct memblock_region *reg; 112 113 for_each_memblock(memory, reg) { 114 phys_addr_t base = reg->base; 115 phys_addr_t top = min(base + reg->size, total_lowmem); 116 117 if (base >= top) 118 continue; 119 base = mmu_mapin_ram(base, top); 120 if (IS_ENABLED(CONFIG_BDI_SWITCH)) 121 __mapin_ram_chunk(reg->base, top); 122 else 123 __mapin_ram_chunk(base, top); 124 } 125 } 126 127 /* Scan the real Linux page tables and return a PTE pointer for 128 * a virtual address in a context. 129 * Returns true (1) if PTE was found, zero otherwise. The pointer to 130 * the PTE pointer is unmodified if PTE is not found. 131 */ 132 static int 133 get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp) 134 { 135 pgd_t *pgd; 136 pud_t *pud; 137 pmd_t *pmd; 138 pte_t *pte; 139 int retval = 0; 140 141 pgd = pgd_offset(mm, addr & PAGE_MASK); 142 if (pgd) { 143 pud = pud_offset(pgd, addr & PAGE_MASK); 144 if (pud && pud_present(*pud)) { 145 pmd = pmd_offset(pud, addr & PAGE_MASK); 146 if (pmd_present(*pmd)) { 147 pte = pte_offset_map(pmd, addr & PAGE_MASK); 148 if (pte) { 149 retval = 1; 150 *ptep = pte; 151 if (pmdp) 152 *pmdp = pmd; 153 /* XXX caller needs to do pte_unmap, yuck */ 154 } 155 } 156 } 157 } 158 return(retval); 159 } 160 161 static int __change_page_attr_noflush(struct page *page, pgprot_t prot) 162 { 163 pte_t *kpte; 164 pmd_t *kpmd; 165 unsigned long address; 166 167 BUG_ON(PageHighMem(page)); 168 address = (unsigned long)page_address(page); 169 170 if (v_block_mapped(address)) 171 return 0; 172 if (!get_pteptr(&init_mm, address, &kpte, &kpmd)) 173 return -EINVAL; 174 __set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0); 175 pte_unmap(kpte); 176 177 return 0; 178 } 179 180 /* 181 * Change the page attributes of an page in the linear mapping. 182 * 183 * THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY 184 */ 185 static int change_page_attr(struct page *page, int numpages, pgprot_t prot) 186 { 187 int i, err = 0; 188 unsigned long flags; 189 struct page *start = page; 190 191 local_irq_save(flags); 192 for (i = 0; i < numpages; i++, page++) { 193 err = __change_page_attr_noflush(page, prot); 194 if (err) 195 break; 196 } 197 wmb(); 198 local_irq_restore(flags); 199 flush_tlb_kernel_range((unsigned long)page_address(start), 200 (unsigned long)page_address(page)); 201 return err; 202 } 203 204 void mark_initmem_nx(void) 205 { 206 struct page *page = virt_to_page(_sinittext); 207 unsigned long numpages = PFN_UP((unsigned long)_einittext) - 208 PFN_DOWN((unsigned long)_sinittext); 209 210 if (v_block_mapped((unsigned long)_stext + 1)) 211 mmu_mark_initmem_nx(); 212 else 213 change_page_attr(page, numpages, PAGE_KERNEL); 214 } 215 216 #ifdef CONFIG_STRICT_KERNEL_RWX 217 void mark_rodata_ro(void) 218 { 219 struct page *page; 220 unsigned long numpages; 221 222 if (v_block_mapped((unsigned long)_sinittext)) { 223 mmu_mark_rodata_ro(); 224 return; 225 } 226 227 page = virt_to_page(_stext); 228 numpages = PFN_UP((unsigned long)_etext) - 229 PFN_DOWN((unsigned long)_stext); 230 231 change_page_attr(page, numpages, PAGE_KERNEL_ROX); 232 /* 233 * mark .rodata as read only. Use __init_begin rather than __end_rodata 234 * to cover NOTES and EXCEPTION_TABLE. 235 */ 236 page = virt_to_page(__start_rodata); 237 numpages = PFN_UP((unsigned long)__init_begin) - 238 PFN_DOWN((unsigned long)__start_rodata); 239 240 change_page_attr(page, numpages, PAGE_KERNEL_RO); 241 242 // mark_initmem_nx() should have already run by now 243 ptdump_check_wx(); 244 } 245 #endif 246 247 #ifdef CONFIG_DEBUG_PAGEALLOC 248 void __kernel_map_pages(struct page *page, int numpages, int enable) 249 { 250 if (PageHighMem(page)) 251 return; 252 253 change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0)); 254 } 255 #endif /* CONFIG_DEBUG_PAGEALLOC */ 256