whiterose

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head32.c (3219B)


      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 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 void __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