root/arch/alpha/mm/init.c

DEFINITIONS

1. pgd_alloc
2. __bad_pagetable
3. __bad_page
4. load_PCB
5. switch_to_system_map
6. callback_init
7. paging_init
8. srm_paging_stop
9. mem_init

   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/pgtable.h>
  28 #include <asm/pgalloc.h>
  29 #include <asm/hwrpb.h>
  30 #include <asm/dma.h>
  31 #include <asm/mmu_context.h>
  32 #include <asm/console.h>
  33 #include <asm/tlb.h>
  34 #include <asm/setup.h>
  35 #include <asm/sections.h>
  36 
  37 extern void die_if_kernel(char *,struct pt_regs *,long);
  38 
  39 static struct pcb_struct original_pcb;
  40 
  41 pgd_t *
  42 pgd_alloc(struct mm_struct *mm)
  43 {
  44         pgd_t *ret, *init;
  45 
  46         ret = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
  47         init = pgd_offset(&init_mm, 0UL);
  48         if (ret) {
  49 #ifdef CONFIG_ALPHA_LARGE_VMALLOC
  50                 memcpy (ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
  51                         (PTRS_PER_PGD - USER_PTRS_PER_PGD - 1)*sizeof(pgd_t));
  52 #else
  53                 pgd_val(ret[PTRS_PER_PGD-2]) = pgd_val(init[PTRS_PER_PGD-2]);
  54 #endif
  55 
  56                 /* The last PGD entry is the VPTB self-map.  */
  57                 pgd_val(ret[PTRS_PER_PGD-1])
  58                   = pte_val(mk_pte(virt_to_page(ret), PAGE_KERNEL));
  59         }
  60         return ret;
  61 }
  62 
  63 
  64 /*
  65  * BAD_PAGE is the page that is used for page faults when linux
  66  * is out-of-memory. Older versions of linux just did a
  67  * do_exit(), but using this instead means there is less risk
  68  * for a process dying in kernel mode, possibly leaving an inode
  69  * unused etc..
  70  *
  71  * BAD_PAGETABLE is the accompanying page-table: it is initialized
  72  * to point to BAD_PAGE entries.
  73  *
  74  * ZERO_PAGE is a special page that is used for zero-initialized
  75  * data and COW.
  76  */
  77 pmd_t *
  78 __bad_pagetable(void)
  79 {
  80         memset((void *) EMPTY_PGT, 0, PAGE_SIZE);
  81         return (pmd_t *) EMPTY_PGT;
  82 }
  83 
  84 pte_t
  85 __bad_page(void)
  86 {
  87         memset((void *) EMPTY_PGE, 0, PAGE_SIZE);
  88         return pte_mkdirty(mk_pte(virt_to_page(EMPTY_PGE), PAGE_SHARED));
  89 }
  90 
  91 static inline unsigned long
  92 load_PCB(struct pcb_struct *pcb)
  93 {
  94         register unsigned long sp __asm__("$30");
  95         pcb->ksp = sp;
  96         return __reload_thread(pcb);
  97 }
  98 
  99 /* Set up initial PCB, VPTB, and other such nicities.  */
 100 
 101 static inline void
 102 switch_to_system_map(void)
 103 {
 104         unsigned long newptbr;
 105         unsigned long original_pcb_ptr;
 106 
 107         /* Initialize the kernel's page tables.  Linux puts the vptb in
 108            the last slot of the L1 page table.  */
 109         memset(swapper_pg_dir, 0, PAGE_SIZE);
 110         newptbr = ((unsigned long) swapper_pg_dir - PAGE_OFFSET) >> PAGE_SHIFT;
 111         pgd_val(swapper_pg_dir[1023]) =
 112                 (newptbr << 32) | pgprot_val(PAGE_KERNEL);
 113 
 114         /* Set the vptb.  This is often done by the bootloader, but 
 115            shouldn't be required.  */
 116         if (hwrpb->vptb != 0xfffffffe00000000UL) {
 117                 wrvptptr(0xfffffffe00000000UL);
 118                 hwrpb->vptb = 0xfffffffe00000000UL;
 119                 hwrpb_update_checksum(hwrpb);
 120         }
 121 
 122         /* Also set up the real kernel PCB while we're at it.  */
 123         init_thread_info.pcb.ptbr = newptbr;
 124         init_thread_info.pcb.flags = 1; /* set FEN, clear everything else */
 125         original_pcb_ptr = load_PCB(&init_thread_info.pcb);
 126         tbia();
 127 
 128         /* Save off the contents of the original PCB so that we can
 129            restore the original console's page tables for a clean reboot.
 130 
 131            Note that the PCB is supposed to be a physical address, but
 132            since KSEG values also happen to work, folks get confused.
 133            Check this here.  */
 134 
 135         if (original_pcb_ptr < PAGE_OFFSET) {
 136                 original_pcb_ptr = (unsigned long)
 137                         phys_to_virt(original_pcb_ptr);
 138         }
 139         original_pcb = *(struct pcb_struct *) original_pcb_ptr;
 140 }
 141 
 142 int callback_init_done;
 143 
 144 void * __init
 145 callback_init(void * kernel_end)
 146 {
 147         struct crb_struct * crb;
 148         pgd_t *pgd;
 149         pmd_t *pmd;
 150         void *two_pages;
 151 
 152         /* Starting at the HWRPB, locate the CRB. */
 153         crb = (struct crb_struct *)((char *)hwrpb + hwrpb->crb_offset);
 154 
 155         if (alpha_using_srm) {
 156                 /* Tell the console whither it is to be remapped. */
 157                 if (srm_fixup(VMALLOC_START, (unsigned long)hwrpb))
 158                         __halt();               /* "We're boned."  --Bender */
 159 
 160                 /* Edit the procedure descriptors for DISPATCH and FIXUP. */
 161                 crb->dispatch_va = (struct procdesc_struct *)
 162                         (VMALLOC_START + (unsigned long)crb->dispatch_va
 163                          - crb->map[0].va);
 164                 crb->fixup_va = (struct procdesc_struct *)
 165                         (VMALLOC_START + (unsigned long)crb->fixup_va
 166                          - crb->map[0].va);
 167         }
 168 
 169         switch_to_system_map();
 170 
 171         /* Allocate one PGD and one PMD.  In the case of SRM, we'll need
 172            these to actually remap the console.  There is an assumption
 173            here that only one of each is needed, and this allows for 8MB.
 174            On systems with larger consoles, additional pages will be
 175            allocated as needed during the mapping process.
 176 
 177            In the case of not SRM, but not CONFIG_ALPHA_LARGE_VMALLOC,
 178            we need to allocate the PGD we use for vmalloc before we start
 179            forking other tasks.  */
 180 
 181         two_pages = (void *)
 182           (((unsigned long)kernel_end + ~PAGE_MASK) & PAGE_MASK);
 183         kernel_end = two_pages + 2*PAGE_SIZE;
 184         memset(two_pages, 0, 2*PAGE_SIZE);
 185 
 186         pgd = pgd_offset_k(VMALLOC_START);
 187         pgd_set(pgd, (pmd_t *)two_pages);
 188         pmd = pmd_offset(pgd, VMALLOC_START);
 189         pmd_set(pmd, (pte_t *)(two_pages + PAGE_SIZE));
 190 
 191         if (alpha_using_srm) {
 192                 static struct vm_struct console_remap_vm;
 193                 unsigned long nr_pages = 0;
 194                 unsigned long vaddr;
 195                 unsigned long i, j;
 196 
 197                 /* calculate needed size */
 198                 for (i = 0; i < crb->map_entries; ++i)
 199                         nr_pages += crb->map[i].count;
 200 
 201                 /* register the vm area */
 202                 console_remap_vm.flags = VM_ALLOC;
 203                 console_remap_vm.size = nr_pages << PAGE_SHIFT;
 204                 vm_area_register_early(&console_remap_vm, PAGE_SIZE);
 205 
 206                 vaddr = (unsigned long)console_remap_vm.addr;
 207 
 208                 /* Set up the third level PTEs and update the virtual
 209                    addresses of the CRB entries.  */
 210                 for (i = 0; i < crb->map_entries; ++i) {
 211                         unsigned long pfn = crb->map[i].pa >> PAGE_SHIFT;
 212                         crb->map[i].va = vaddr;
 213                         for (j = 0; j < crb->map[i].count; ++j) {
 214                                 /* Newer consoles (especially on larger
 215                                    systems) may require more pages of
 216                                    PTEs. Grab additional pages as needed. */
 217                                 if (pmd != pmd_offset(pgd, vaddr)) {
 218                                         memset(kernel_end, 0, PAGE_SIZE);
 219                                         pmd = pmd_offset(pgd, vaddr);
 220                                         pmd_set(pmd, (pte_t *)kernel_end);
 221                                         kernel_end += PAGE_SIZE;
 222                                 }
 223                                 set_pte(pte_offset_kernel(pmd, vaddr),
 224                                         pfn_pte(pfn, PAGE_KERNEL));
 225                                 pfn++;
 226                                 vaddr += PAGE_SIZE;
 227                         }
 228                 }
 229         }
 230 
 231         callback_init_done = 1;
 232         return kernel_end;
 233 }
 234 
 235 
 236 #ifndef CONFIG_DISCONTIGMEM
 237 /*
 238  * paging_init() sets up the memory map.
 239  */
 240 void __init paging_init(void)
 241 {
 242         unsigned long zones_size[MAX_NR_ZONES] = {0, };
 243         unsigned long dma_pfn, high_pfn;
 244 
 245         dma_pfn = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
 246         high_pfn = max_pfn = max_low_pfn;
 247 
 248         if (dma_pfn >= high_pfn)
 249                 zones_size[ZONE_DMA] = high_pfn;
 250         else {
 251                 zones_size[ZONE_DMA] = dma_pfn;
 252                 zones_size[ZONE_NORMAL] = high_pfn - dma_pfn;
 253         }
 254 
 255         /* Initialize mem_map[].  */
 256         free_area_init(zones_size);
 257 
 258         /* Initialize the kernel's ZERO_PGE. */
 259         memset((void *)ZERO_PGE, 0, PAGE_SIZE);
 260 }
 261 #endif /* CONFIG_DISCONTIGMEM */
 262 
 263 #if defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_SRM)
 264 void
 265 srm_paging_stop (void)
 266 {
 267         /* Move the vptb back to where the SRM console expects it.  */
 268         swapper_pg_dir[1] = swapper_pg_dir[1023];
 269         tbia();
 270         wrvptptr(0x200000000UL);
 271         hwrpb->vptb = 0x200000000UL;
 272         hwrpb_update_checksum(hwrpb);
 273 
 274         /* Reload the page tables that the console had in use.  */
 275         load_PCB(&original_pcb);
 276         tbia();
 277 }
 278 #endif
 279 
 280 void __init
 281 mem_init(void)
 282 {
 283         set_max_mapnr(max_low_pfn);
 284         high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
 285         memblock_free_all();
 286         mem_init_print_info(NULL);
 287 }