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// SPDX-License-Identifier: GPL-2.0
/*
* linux/arch/i386/kernel/head32.c -- prepare to run common code
*
* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
* Copyright (C) 2007 Eric Biederman <ebiederm@xmission.com>
*/
#include <linux/init.h>
#include <linux/start_kernel.h>
#include <linux/mm.h>
#include <linux/memblock.h>
#include <asm/desc.h>
#include <asm/setup.h>
#include <asm/sections.h>
#include <asm/e820/api.h>
#include <asm/page.h>
#include <asm/apic.h>
#include <asm/io_apic.h>
#include <asm/bios_ebda.h>
#include <asm/tlbflush.h>
#include <asm/bootparam_utils.h>
static void __init i386_default_early_setup(void)
{
/* Initialize 32bit specific setup functions */
x86_init.resources.reserve_resources = i386_reserve_resources;
x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
}
asmlinkage __visible void __init __noreturn i386_start_kernel(void)
{
/* Make sure IDT is set up before any exception happens */
idt_setup_early_handler();
cr4_init_shadow();
sanitize_boot_params(&boot_params);
x86_early_init_platform_quirks();
/* Call the subarch specific early setup function */
switch (boot_params.hdr.hardware_subarch) {
case X86_SUBARCH_INTEL_MID:
x86_intel_mid_early_setup();
break;
case X86_SUBARCH_CE4100:
x86_ce4100_early_setup();
break;
default:
i386_default_early_setup();
break;
}
start_kernel();
}
/*
* Initialize page tables. This creates a PDE and a set of page
* tables, which are located immediately beyond __brk_base. The variable
* _brk_end is set up to point to the first "safe" location.
* Mappings are created both at virtual address 0 (identity mapping)
* and PAGE_OFFSET for up to _end.
*
* In PAE mode initial_page_table is statically defined to contain
* enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
* entries). The identity mapping is handled by pointing two PGD entries
* to the first kernel PMD. Note the upper half of each PMD or PTE are
* always zero at this stage.
*/
#ifdef CONFIG_X86_PAE
typedef pmd_t pl2_t;
#define pl2_base initial_pg_pmd
#define SET_PL2(val) { .pmd = (val), }
#else
typedef pgd_t pl2_t;
#define pl2_base initial_page_table
#define SET_PL2(val) { .pgd = (val), }
#endif
static __init __no_stack_protector pte_t init_map(pte_t pte, pte_t **ptep, pl2_t **pl2p,
const unsigned long limit)
{
while ((pte.pte & PTE_PFN_MASK) < limit) {
pl2_t pl2 = SET_PL2((unsigned long)*ptep | PDE_IDENT_ATTR);
int i;
**pl2p = pl2;
if (!IS_ENABLED(CONFIG_X86_PAE)) {
/* Kernel PDE entry */
*(*pl2p + ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2;
}
for (i = 0; i < PTRS_PER_PTE; i++) {
**ptep = pte;
pte.pte += PAGE_SIZE;
(*ptep)++;
}
(*pl2p)++;
}
return pte;
}
void __init __no_stack_protector mk_early_pgtbl_32(void)
{
/* Enough space to fit pagetables for the low memory linear map */
const unsigned long limit = __pa_nodebug(_end) +
(PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT);
pte_t pte, *ptep = (pte_t *)__pa_nodebug(__brk_base);
pl2_t *pl2p = (pl2_t *)__pa_nodebug(pl2_base);
unsigned long *ptr;
pte.pte = PTE_IDENT_ATTR;
pte = init_map(pte, &ptep, &pl2p, limit);
ptr = (unsigned long *)__pa_nodebug(&max_pfn_mapped);
/* Can't use pte_pfn() since it's a call with CONFIG_PARAVIRT */
*ptr = (pte.pte & PTE_PFN_MASK) >> PAGE_SHIFT;
ptr = (unsigned long *)__pa_nodebug(&_brk_end);
*ptr = (unsigned long)ptep + PAGE_OFFSET;
}
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