From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 7 Apr 2024 20:49:45 +0200
Subject: Adding upstream version 6.1.76.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 arch/x86/kernel/head32.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)
 create mode 100644 arch/x86/kernel/head32.c

(limited to 'arch/x86/kernel/head32.c')

diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
new file mode 100644
index 000000000..ec6fefbfd
--- /dev/null
+++ b/arch/x86/kernel/head32.c
@@ -0,0 +1,119 @@
+// 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 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.
+ */
+void __init mk_early_pgtbl_32(void)
+{
+#ifdef __pa
+#undef __pa
+#endif
+#define __pa(x)  ((unsigned long)(x) - PAGE_OFFSET)
+	pte_t pte, *ptep;
+	int i;
+	unsigned long *ptr;
+	/* Enough space to fit pagetables for the low memory linear map */
+	const unsigned long limit = __pa(_end) +
+		(PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT);
+#ifdef CONFIG_X86_PAE
+	pmd_t pl2, *pl2p = (pmd_t *)__pa(initial_pg_pmd);
+#define SET_PL2(pl2, val)    { (pl2).pmd = (val); }
+#else
+	pgd_t pl2, *pl2p = (pgd_t *)__pa(initial_page_table);
+#define SET_PL2(pl2, val)   { (pl2).pgd = (val); }
+#endif
+
+	ptep = (pte_t *)__pa(__brk_base);
+	pte.pte = PTE_IDENT_ATTR;
+
+	while ((pte.pte & PTE_PFN_MASK) < limit) {
+
+		SET_PL2(pl2, (unsigned long)ptep | PDE_IDENT_ATTR);
+		*pl2p = pl2;
+#ifndef CONFIG_X86_PAE
+		/* Kernel PDE entry */
+		*(pl2p +  ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2;
+#endif
+		for (i = 0; i < PTRS_PER_PTE; i++) {
+			*ptep = pte;
+			pte.pte += PAGE_SIZE;
+			ptep++;
+		}
+
+		pl2p++;
+	}
+
+	ptr = (unsigned long *)__pa(&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(&_brk_end);
+	*ptr = (unsigned long)ptep + PAGE_OFFSET;
+}
+
-- 
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