arch/alpha/mm/init.c

   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((void *) EMPTY_PGT, 0, PAGE_SIZE);
  80         return (pmd_t *) EMPTY_PGT;
  81 }
  82
  83 pte_t
  84 __bad_page(void)
  85 {
  86         memset((void *) 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 #ifndef CONFIG_DISCONTIGMEM
 240 /*
 241  * paging_init() sets up the memory map.
 242  */
 243 void __init paging_init(void)
 244 {
 245         unsigned long max_zone_pfn[MAX_NR_ZONES] = {0, };
 246         unsigned long dma_pfn;
 247
 248         dma_pfn = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
 249         max_pfn = max_low_pfn;
 250
 251         max_zone_pfn[ZONE_DMA] = dma_pfn;
 252         max_zone_pfn[ZONE_NORMAL] = max_pfn;
 253
 254         /* Initialize mem_map[].  */
 255         free_area_init(max_zone_pfn);
 256
 257         /* Initialize the kernel's ZERO_PGE. */
 258         memset((void *)ZERO_PGE, 0, PAGE_SIZE);
 259 }
 260 #endif /* CONFIG_DISCONTIGMEM */
 261
 262 #if defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_SRM)
 263 void
 264 srm_paging_stop (void)
 265 {
 266         /* Move the vptb back to where the SRM console expects it.  */
 267         swapper_pg_dir[1] = swapper_pg_dir[1023];
 268         tbia();
 269         wrvptptr(0x200000000UL);
 270         hwrpb->vptb = 0x200000000UL;
 271         hwrpb_update_checksum(hwrpb);
 272
 273         /* Reload the page tables that the console had in use.  */
 274         load_PCB(&original_pcb);
 275         tbia();
 276 }
 277 #endif
 278
 279 void __init
 280 mem_init(void)
 281 {
 282         set_max_mapnr(max_low_pfn);
 283         high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
 284         memblock_free_all();
 285         mem_init_print_info(NULL);
 286 }