LXR linux/arch/x86/kernel/head32.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  linux/arch/i386/kernel/head32.c -- prepare to run common code
   4 *
   5 *  Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
   6 *  Copyright (C) 2007 Eric Biederman <ebiederm@xmission.com>
   7 */
   8
   9#include <linux/init.h>
  10#include <linux/start_kernel.h>
  11#include <linux/mm.h>
  12#include <linux/memblock.h>
  13
  14#include <asm/desc.h>
  15#include <asm/setup.h>
  16#include <asm/sections.h>
  17#include <asm/e820/api.h>
  18#include <asm/page.h>
  19#include <asm/apic.h>
  20#include <asm/io_apic.h>
  21#include <asm/bios_ebda.h>
  22#include <asm/tlbflush.h>
  23#include <asm/bootparam_utils.h>
  24
  25static void __init i386_default_early_setup(void)
  26{
  27        /* Initialize 32bit specific setup functions */
  28        x86_init.resources.reserve_resources = i386_reserve_resources;
  29        x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
  30}
  31
  32asmlinkage __visible void __init i386_start_kernel(void)
  33{
  34        /* Make sure IDT is set up before any exception happens */
  35        idt_setup_early_handler();
  36
  37        cr4_init_shadow();
  38
  39        sanitize_boot_params(&boot_params);
  40
  41        x86_early_init_platform_quirks();
  42
  43        /* Call the subarch specific early setup function */
  44        switch (boot_params.hdr.hardware_subarch) {
  45        case X86_SUBARCH_INTEL_MID:
  46                x86_intel_mid_early_setup();
  47                break;
  48        case X86_SUBARCH_CE4100:
  49                x86_ce4100_early_setup();
  50                break;
  51        default:
  52                i386_default_early_setup();
  53                break;
  54        }
  55
  56        start_kernel();
  57}
  58
  59/*
  60 * Initialize page tables.  This creates a PDE and a set of page
  61 * tables, which are located immediately beyond __brk_base.  The variable
  62 * _brk_end is set up to point to the first "safe" location.
  63 * Mappings are created both at virtual address 0 (identity mapping)
  64 * and PAGE_OFFSET for up to _end.
  65 *
  66 * In PAE mode initial_page_table is statically defined to contain
  67 * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
  68 * entries). The identity mapping is handled by pointing two PGD entries
  69 * to the first kernel PMD. Note the upper half of each PMD or PTE are
  70 * always zero at this stage.
  71 */
  72void __init mk_early_pgtbl_32(void)
  73{
  74#ifdef __pa
  75#undef __pa
  76#endif
  77#define __pa(x)  ((unsigned long)(x) - PAGE_OFFSET)
  78        pte_t pte, *ptep;
  79        int i;
  80        unsigned long *ptr;
  81        /* Enough space to fit pagetables for the low memory linear map */
  82        const unsigned long limit = __pa(_end) +
  83                (PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT);
  84#ifdef CONFIG_X86_PAE
  85        pmd_t pl2, *pl2p = (pmd_t *)__pa(initial_pg_pmd);
  86#define SET_PL2(pl2, val)    { (pl2).pmd = (val); }
  87#else
  88        pgd_t pl2, *pl2p = (pgd_t *)__pa(initial_page_table);
  89#define SET_PL2(pl2, val)   { (pl2).pgd = (val); }
  90#endif
  91
  92        ptep = (pte_t *)__pa(__brk_base);
  93        pte.pte = PTE_IDENT_ATTR;
  94
  95        while ((pte.pte & PTE_PFN_MASK) < limit) {
  96
  97                SET_PL2(pl2, (unsigned long)ptep | PDE_IDENT_ATTR);
  98                *pl2p = pl2;
  99#ifndef CONFIG_X86_PAE
 100                /* Kernel PDE entry */
 101                *(pl2p +  ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2;
 102#endif
 103                for (i = 0; i < PTRS_PER_PTE; i++) {
 104                        *ptep = pte;
 105                        pte.pte += PAGE_SIZE;
 106                        ptep++;
 107                }
 108
 109                pl2p++;
 110        }
 111
 112        ptr = (unsigned long *)__pa(&max_pfn_mapped);
 113        /* Can't use pte_pfn() since it's a call with CONFIG_PARAVIRT */
 114        *ptr = (pte.pte & PTE_PFN_MASK) >> PAGE_SHIFT;
 115
 116        ptr = (unsigned long *)__pa(&_brk_end);
 117        *ptr = (unsigned long)ptep + PAGE_OFFSET;
 118}
 119
 120