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 25 static 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 32 asmlinkage __visible void __init __noreturn 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 */ 72 #ifdef CONFIG_X86_PAE 73 typedef pmd_t pl2_t; 74 #define pl2_base initial_pg_pmd 75 #define SET_PL2(val) { .pmd = (val), } 76 #else 77 typedef pgd_t pl2_t; 78 #define pl2_base initial_page_table 79 #define SET_PL2(val) { .pgd = (val), } 80 #endif 81 82 static __init __no_stack_protector pte_t init_map(pte_t pte, pte_t **ptep, pl2_t **pl2p, 83 const unsigned long limit) 84 { 85 while ((pte.pte & PTE_PFN_MASK) < limit) { 86 pl2_t pl2 = SET_PL2((unsigned long)*ptep | PDE_IDENT_ATTR); 87 int i; 88 89 **pl2p = pl2; 90 if (!IS_ENABLED(CONFIG_X86_PAE)) { 91 /* Kernel PDE entry */ 92 *(*pl2p + ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2; 93 } 94 95 for (i = 0; i < PTRS_PER_PTE; i++) { 96 **ptep = pte; 97 pte.pte += PAGE_SIZE; 98 (*ptep)++; 99 } 100 (*pl2p)++; 101 } 102 return pte; 103 } 104 105 void __init __no_stack_protector mk_early_pgtbl_32(void) 106 { 107 /* Enough space to fit pagetables for the low memory linear map */ 108 const unsigned long limit = __pa_nodebug(_end) + 109 (PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT); 110 pte_t pte, *ptep = (pte_t *)__pa_nodebug(__brk_base); 111 pl2_t *pl2p = (pl2_t *)__pa_nodebug(pl2_base); 112 unsigned long *ptr; 113 114 pte.pte = PTE_IDENT_ATTR; 115 pte = init_map(pte, &ptep, &pl2p, limit); 116 117 ptr = (unsigned long *)__pa_nodebug(&max_pfn_mapped); 118 /* Can't use pte_pfn() since it's a call with CONFIG_PARAVIRT */ 119 *ptr = (pte.pte & PTE_PFN_MASK) >> PAGE_SHIFT; 120 121 ptr = (unsigned long *)__pa_nodebug(&_brk_end); 122 *ptr = (unsigned long)ptep + PAGE_OFFSET; 123 } 124