1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/arch/alpha/mm/init.c 4 * 5 * Copyright (C) 1995 Linus Torvalds 6 */ 7 8 /* 2.3.x zone allocator, 1999 Andrea Arcangeli <andrea@suse.de> */ 9 10 #include <linux/pagemap.h> 11 #include <linux/signal.h> 12 #include <linux/sched.h> 13 #include <linux/kernel.h> 14 #include <linux/errno.h> 15 #include <linux/string.h> 16 #include <linux/types.h> 17 #include <linux/ptrace.h> 18 #include <linux/mman.h> 19 #include <linux/mm.h> 20 #include <linux/swap.h> 21 #include <linux/init.h> 22 #include <linux/memblock.h> /* max_low_pfn */ 23 #include <linux/vmalloc.h> 24 #include <linux/gfp.h> 25 26 #include <linux/uaccess.h> 27 #include <asm/pgalloc.h> 28 #include <asm/hwrpb.h> 29 #include <asm/dma.h> 30 #include <asm/mmu_context.h> 31 #include <asm/console.h> 32 #include <asm/tlb.h> 33 #include <asm/setup.h> 34 #include <asm/sections.h> 35 36 extern void die_if_kernel(char *,struct pt_regs *,long); 37 38 static struct pcb_struct original_pcb; 39 40 pgd_t * 41 pgd_alloc(struct mm_struct *mm) 42 { 43 pgd_t *ret, *init; 44 45 ret = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO); 46 init = pgd_offset(&init_mm, 0UL); 47 if (ret) { 48 #ifdef CONFIG_ALPHA_LARGE_VMALLOC 49 memcpy (ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD, 50 (PTRS_PER_PGD - USER_PTRS_PER_PGD - 1)*sizeof(pgd_t)); 51 #else 52 pgd_val(ret[PTRS_PER_PGD-2]) = pgd_val(init[PTRS_PER_PGD-2]); 53 #endif 54 55 /* The last PGD entry is the VPTB self-map. */ 56 pgd_val(ret[PTRS_PER_PGD-1]) 57 = pte_val(mk_pte(virt_to_page(ret), PAGE_KERNEL)); 58 } 59 return ret; 60 } 61 62 63 /* 64 * BAD_PAGE is the page that is used for page faults when linux 65 * is out-of-memory. Older versions of linux just did a 66 * do_exit(), but using this instead means there is less risk 67 * for a process dying in kernel mode, possibly leaving an inode 68 * unused etc.. 69 * 70 * BAD_PAGETABLE is the accompanying page-table: it is initialized 71 * to point to BAD_PAGE entries. 72 * 73 * ZERO_PAGE is a special page that is used for zero-initialized 74 * data and COW. 75 */ 76 pmd_t * 77 __bad_pagetable(void) 78 { 79 memset(absolute_pointer(EMPTY_PGT), 0, PAGE_SIZE); 80 return (pmd_t *) EMPTY_PGT; 81 } 82 83 pte_t 84 __bad_page(void) 85 { 86 memset(absolute_pointer(EMPTY_PGE), 0, PAGE_SIZE); 87 return pte_mkdirty(mk_pte(virt_to_page(EMPTY_PGE), PAGE_SHARED)); 88 } 89 90 static inline unsigned long 91 load_PCB(struct pcb_struct *pcb) 92 { 93 register unsigned long sp __asm__("$30"); 94 pcb->ksp = sp; 95 return __reload_thread(pcb); 96 } 97 98 /* Set up initial PCB, VPTB, and other such nicities. */ 99 100 static inline void 101 switch_to_system_map(void) 102 { 103 unsigned long newptbr; 104 unsigned long original_pcb_ptr; 105 106 /* Initialize the kernel's page tables. Linux puts the vptb in 107 the last slot of the L1 page table. */ 108 memset(swapper_pg_dir, 0, PAGE_SIZE); 109 newptbr = ((unsigned long) swapper_pg_dir - PAGE_OFFSET) >> PAGE_SHIFT; 110 pgd_val(swapper_pg_dir[1023]) = 111 (newptbr << 32) | pgprot_val(PAGE_KERNEL); 112 113 /* Set the vptb. This is often done by the bootloader, but 114 shouldn't be required. */ 115 if (hwrpb->vptb != 0xfffffffe00000000UL) { 116 wrvptptr(0xfffffffe00000000UL); 117 hwrpb->vptb = 0xfffffffe00000000UL; 118 hwrpb_update_checksum(hwrpb); 119 } 120 121 /* Also set up the real kernel PCB while we're at it. */ 122 init_thread_info.pcb.ptbr = newptbr; 123 init_thread_info.pcb.flags = 1; /* set FEN, clear everything else */ 124 original_pcb_ptr = load_PCB(&init_thread_info.pcb); 125 tbia(); 126 127 /* Save off the contents of the original PCB so that we can 128 restore the original console's page tables for a clean reboot. 129 130 Note that the PCB is supposed to be a physical address, but 131 since KSEG values also happen to work, folks get confused. 132 Check this here. */ 133 134 if (original_pcb_ptr < PAGE_OFFSET) { 135 original_pcb_ptr = (unsigned long) 136 phys_to_virt(original_pcb_ptr); 137 } 138 original_pcb = *(struct pcb_struct *) original_pcb_ptr; 139 } 140 141 int callback_init_done; 142 143 void * __init 144 callback_init(void * kernel_end) 145 { 146 struct crb_struct * crb; 147 pgd_t *pgd; 148 p4d_t *p4d; 149 pud_t *pud; 150 pmd_t *pmd; 151 void *two_pages; 152 153 /* Starting at the HWRPB, locate the CRB. */ 154 crb = (struct crb_struct *)((char *)hwrpb + hwrpb->crb_offset); 155 156 if (alpha_using_srm) { 157 /* Tell the console whither it is to be remapped. */ 158 if (srm_fixup(VMALLOC_START, (unsigned long)hwrpb)) 159 __halt(); /* "We're boned." --Bender */ 160 161 /* Edit the procedure descriptors for DISPATCH and FIXUP. */ 162 crb->dispatch_va = (struct procdesc_struct *) 163 (VMALLOC_START + (unsigned long)crb->dispatch_va 164 - crb->map[0].va); 165 crb->fixup_va = (struct procdesc_struct *) 166 (VMALLOC_START + (unsigned long)crb->fixup_va 167 - crb->map[0].va); 168 } 169 170 switch_to_system_map(); 171 172 /* Allocate one PGD and one PMD. In the case of SRM, we'll need 173 these to actually remap the console. There is an assumption 174 here that only one of each is needed, and this allows for 8MB. 175 On systems with larger consoles, additional pages will be 176 allocated as needed during the mapping process. 177 178 In the case of not SRM, but not CONFIG_ALPHA_LARGE_VMALLOC, 179 we need to allocate the PGD we use for vmalloc before we start 180 forking other tasks. */ 181 182 two_pages = (void *) 183 (((unsigned long)kernel_end + ~PAGE_MASK) & PAGE_MASK); 184 kernel_end = two_pages + 2*PAGE_SIZE; 185 memset(two_pages, 0, 2*PAGE_SIZE); 186 187 pgd = pgd_offset_k(VMALLOC_START); 188 p4d = p4d_offset(pgd, VMALLOC_START); 189 pud = pud_offset(p4d, VMALLOC_START); 190 pud_set(pud, (pmd_t *)two_pages); 191 pmd = pmd_offset(pud, VMALLOC_START); 192 pmd_set(pmd, (pte_t *)(two_pages + PAGE_SIZE)); 193 194 if (alpha_using_srm) { 195 static struct vm_struct console_remap_vm; 196 unsigned long nr_pages = 0; 197 unsigned long vaddr; 198 unsigned long i, j; 199 200 /* calculate needed size */ 201 for (i = 0; i < crb->map_entries; ++i) 202 nr_pages += crb->map[i].count; 203 204 /* register the vm area */ 205 console_remap_vm.flags = VM_ALLOC; 206 console_remap_vm.size = nr_pages << PAGE_SHIFT; 207 vm_area_register_early(&console_remap_vm, PAGE_SIZE); 208 209 vaddr = (unsigned long)console_remap_vm.addr; 210 211 /* Set up the third level PTEs and update the virtual 212 addresses of the CRB entries. */ 213 for (i = 0; i < crb->map_entries; ++i) { 214 unsigned long pfn = crb->map[i].pa >> PAGE_SHIFT; 215 crb->map[i].va = vaddr; 216 for (j = 0; j < crb->map[i].count; ++j) { 217 /* Newer consoles (especially on larger 218 systems) may require more pages of 219 PTEs. Grab additional pages as needed. */ 220 if (pmd != pmd_offset(pud, vaddr)) { 221 memset(kernel_end, 0, PAGE_SIZE); 222 pmd = pmd_offset(pud, vaddr); 223 pmd_set(pmd, (pte_t *)kernel_end); 224 kernel_end += PAGE_SIZE; 225 } 226 set_pte(pte_offset_kernel(pmd, vaddr), 227 pfn_pte(pfn, PAGE_KERNEL)); 228 pfn++; 229 vaddr += PAGE_SIZE; 230 } 231 } 232 } 233 234 callback_init_done = 1; 235 return kernel_end; 236 } 237 238 /* 239 * paging_init() sets up the memory map. 240 */ 241 void __init paging_init(void) 242 { 243 unsigned long max_zone_pfn[MAX_NR_ZONES] = {0, }; 244 unsigned long dma_pfn; 245 246 dma_pfn = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT; 247 max_pfn = max_low_pfn; 248 249 max_zone_pfn[ZONE_DMA] = dma_pfn; 250 max_zone_pfn[ZONE_NORMAL] = max_pfn; 251 252 /* Initialize mem_map[]. */ 253 free_area_init(max_zone_pfn); 254 255 /* Initialize the kernel's ZERO_PGE. */ 256 memset(absolute_pointer(ZERO_PGE), 0, PAGE_SIZE); 257 } 258 259 #if defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_SRM) 260 void 261 srm_paging_stop (void) 262 { 263 /* Move the vptb back to where the SRM console expects it. */ 264 swapper_pg_dir[1] = swapper_pg_dir[1023]; 265 tbia(); 266 wrvptptr(0x200000000UL); 267 hwrpb->vptb = 0x200000000UL; 268 hwrpb_update_checksum(hwrpb); 269 270 /* Reload the page tables that the console had in use. */ 271 load_PCB(&original_pcb); 272 tbia(); 273 } 274 #endif 275 276 void __init 277 mem_init(void) 278 { 279 set_max_mapnr(max_low_pfn); 280 high_memory = (void *) __va(max_low_pfn * PAGE_SIZE); 281 memblock_free_all(); 282 } 283