From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Thu, 11 Apr 2024 10:27:49 +0200
Subject: Adding upstream version 6.6.15.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 arch/x86/mm/init_32.c | 805 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 805 insertions(+)
 create mode 100644 arch/x86/mm/init_32.c

(limited to 'arch/x86/mm/init_32.c')

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
new file mode 100644
index 0000000000..b63403d717
--- /dev/null
+++ b/arch/x86/mm/init_32.c
@@ -0,0 +1,805 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ *
+ *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
+ */
+
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/swap.h>
+#include <linux/smp.h>
+#include <linux/init.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <linux/pci.h>
+#include <linux/pfn.h>
+#include <linux/poison.h>
+#include <linux/memblock.h>
+#include <linux/proc_fs.h>
+#include <linux/memory_hotplug.h>
+#include <linux/initrd.h>
+#include <linux/cpumask.h>
+#include <linux/gfp.h>
+
+#include <asm/asm.h>
+#include <asm/bios_ebda.h>
+#include <asm/processor.h>
+#include <linux/uaccess.h>
+#include <asm/dma.h>
+#include <asm/fixmap.h>
+#include <asm/e820/api.h>
+#include <asm/apic.h>
+#include <asm/bugs.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+#include <asm/olpc_ofw.h>
+#include <asm/pgalloc.h>
+#include <asm/sections.h>
+#include <asm/setup.h>
+#include <asm/set_memory.h>
+#include <asm/page_types.h>
+#include <asm/cpu_entry_area.h>
+#include <asm/init.h>
+#include <asm/pgtable_areas.h>
+#include <asm/numa.h>
+
+#include "mm_internal.h"
+
+unsigned long highstart_pfn, highend_pfn;
+
+bool __read_mostly __vmalloc_start_set = false;
+
+/*
+ * Creates a middle page table and puts a pointer to it in the
+ * given global directory entry. This only returns the gd entry
+ * in non-PAE compilation mode, since the middle layer is folded.
+ */
+static pmd_t * __init one_md_table_init(pgd_t *pgd)
+{
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd_table;
+
+#ifdef CONFIG_X86_PAE
+	if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
+		pmd_table = (pmd_t *)alloc_low_page();
+		set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
+		p4d = p4d_offset(pgd, 0);
+		pud = pud_offset(p4d, 0);
+		BUG_ON(pmd_table != pmd_offset(pud, 0));
+
+		return pmd_table;
+	}
+#endif
+	p4d = p4d_offset(pgd, 0);
+	pud = pud_offset(p4d, 0);
+	pmd_table = pmd_offset(pud, 0);
+
+	return pmd_table;
+}
+
+/*
+ * Create a page table and place a pointer to it in a middle page
+ * directory entry:
+ */
+static pte_t * __init one_page_table_init(pmd_t *pmd)
+{
+	if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
+		pte_t *page_table = (pte_t *)alloc_low_page();
+
+		set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
+		BUG_ON(page_table != pte_offset_kernel(pmd, 0));
+	}
+
+	return pte_offset_kernel(pmd, 0);
+}
+
+pmd_t * __init populate_extra_pmd(unsigned long vaddr)
+{
+	int pgd_idx = pgd_index(vaddr);
+	int pmd_idx = pmd_index(vaddr);
+
+	return one_md_table_init(swapper_pg_dir + pgd_idx) + pmd_idx;
+}
+
+pte_t * __init populate_extra_pte(unsigned long vaddr)
+{
+	int pte_idx = pte_index(vaddr);
+	pmd_t *pmd;
+
+	pmd = populate_extra_pmd(vaddr);
+	return one_page_table_init(pmd) + pte_idx;
+}
+
+static unsigned long __init
+page_table_range_init_count(unsigned long start, unsigned long end)
+{
+	unsigned long count = 0;
+#ifdef CONFIG_HIGHMEM
+	int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
+	int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
+	int pgd_idx, pmd_idx;
+	unsigned long vaddr;
+
+	if (pmd_idx_kmap_begin == pmd_idx_kmap_end)
+		return 0;
+
+	vaddr = start;
+	pgd_idx = pgd_index(vaddr);
+	pmd_idx = pmd_index(vaddr);
+
+	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd_idx++) {
+		for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
+							pmd_idx++) {
+			if ((vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin &&
+			    (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end)
+				count++;
+			vaddr += PMD_SIZE;
+		}
+		pmd_idx = 0;
+	}
+#endif
+	return count;
+}
+
+static pte_t *__init page_table_kmap_check(pte_t *pte, pmd_t *pmd,
+					   unsigned long vaddr, pte_t *lastpte,
+					   void **adr)
+{
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * Something (early fixmap) may already have put a pte
+	 * page here, which causes the page table allocation
+	 * to become nonlinear. Attempt to fix it, and if it
+	 * is still nonlinear then we have to bug.
+	 */
+	int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
+	int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
+
+	if (pmd_idx_kmap_begin != pmd_idx_kmap_end
+	    && (vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin
+	    && (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end) {
+		pte_t *newpte;
+		int i;
+
+		BUG_ON(after_bootmem);
+		newpte = *adr;
+		for (i = 0; i < PTRS_PER_PTE; i++)
+			set_pte(newpte + i, pte[i]);
+		*adr = (void *)(((unsigned long)(*adr)) + PAGE_SIZE);
+
+		set_pmd(pmd, __pmd(__pa(newpte)|_PAGE_TABLE));
+		BUG_ON(newpte != pte_offset_kernel(pmd, 0));
+		__flush_tlb_all();
+
+		pte = newpte;
+	}
+	BUG_ON(vaddr < fix_to_virt(FIX_KMAP_BEGIN - 1)
+	       && vaddr > fix_to_virt(FIX_KMAP_END)
+	       && lastpte && lastpte + PTRS_PER_PTE != pte);
+#endif
+	return pte;
+}
+
+/*
+ * This function initializes a certain range of kernel virtual memory
+ * with new bootmem page tables, everywhere page tables are missing in
+ * the given range.
+ *
+ * NOTE: The pagetables are allocated contiguous on the physical space
+ * so we can cache the place of the first one and move around without
+ * checking the pgd every time.
+ */
+static void __init
+page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd_base)
+{
+	int pgd_idx, pmd_idx;
+	unsigned long vaddr;
+	pgd_t *pgd;
+	pmd_t *pmd;
+	pte_t *pte = NULL;
+	unsigned long count = page_table_range_init_count(start, end);
+	void *adr = NULL;
+
+	if (count)
+		adr = alloc_low_pages(count);
+
+	vaddr = start;
+	pgd_idx = pgd_index(vaddr);
+	pmd_idx = pmd_index(vaddr);
+	pgd = pgd_base + pgd_idx;
+
+	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
+		pmd = one_md_table_init(pgd);
+		pmd = pmd + pmd_index(vaddr);
+		for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
+							pmd++, pmd_idx++) {
+			pte = page_table_kmap_check(one_page_table_init(pmd),
+						    pmd, vaddr, pte, &adr);
+
+			vaddr += PMD_SIZE;
+		}
+		pmd_idx = 0;
+	}
+}
+
+static inline int is_x86_32_kernel_text(unsigned long addr)
+{
+	if (addr >= (unsigned long)_text && addr <= (unsigned long)__init_end)
+		return 1;
+	return 0;
+}
+
+/*
+ * This maps the physical memory to kernel virtual address space, a total
+ * of max_low_pfn pages, by creating page tables starting from address
+ * PAGE_OFFSET:
+ */
+unsigned long __init
+kernel_physical_mapping_init(unsigned long start,
+			     unsigned long end,
+			     unsigned long page_size_mask,
+			     pgprot_t prot)
+{
+	int use_pse = page_size_mask == (1<<PG_LEVEL_2M);
+	unsigned long last_map_addr = end;
+	unsigned long start_pfn, end_pfn;
+	pgd_t *pgd_base = swapper_pg_dir;
+	int pgd_idx, pmd_idx, pte_ofs;
+	unsigned long pfn;
+	pgd_t *pgd;
+	pmd_t *pmd;
+	pte_t *pte;
+	unsigned pages_2m, pages_4k;
+	int mapping_iter;
+
+	start_pfn = start >> PAGE_SHIFT;
+	end_pfn = end >> PAGE_SHIFT;
+
+	/*
+	 * First iteration will setup identity mapping using large/small pages
+	 * based on use_pse, with other attributes same as set by
+	 * the early code in head_32.S
+	 *
+	 * Second iteration will setup the appropriate attributes (NX, GLOBAL..)
+	 * as desired for the kernel identity mapping.
+	 *
+	 * This two pass mechanism conforms to the TLB app note which says:
+	 *
+	 *     "Software should not write to a paging-structure entry in a way
+	 *      that would change, for any linear address, both the page size
+	 *      and either the page frame or attributes."
+	 */
+	mapping_iter = 1;
+
+	if (!boot_cpu_has(X86_FEATURE_PSE))
+		use_pse = 0;
+
+repeat:
+	pages_2m = pages_4k = 0;
+	pfn = start_pfn;
+	pgd_idx = pgd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
+	pgd = pgd_base + pgd_idx;
+	for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
+		pmd = one_md_table_init(pgd);
+
+		if (pfn >= end_pfn)
+			continue;
+#ifdef CONFIG_X86_PAE
+		pmd_idx = pmd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
+		pmd += pmd_idx;
+#else
+		pmd_idx = 0;
+#endif
+		for (; pmd_idx < PTRS_PER_PMD && pfn < end_pfn;
+		     pmd++, pmd_idx++) {
+			unsigned int addr = pfn * PAGE_SIZE + PAGE_OFFSET;
+
+			/*
+			 * Map with big pages if possible, otherwise
+			 * create normal page tables:
+			 */
+			if (use_pse) {
+				unsigned int addr2;
+				pgprot_t prot = PAGE_KERNEL_LARGE;
+				/*
+				 * first pass will use the same initial
+				 * identity mapping attribute + _PAGE_PSE.
+				 */
+				pgprot_t init_prot =
+					__pgprot(PTE_IDENT_ATTR |
+						 _PAGE_PSE);
+
+				pfn &= PMD_MASK >> PAGE_SHIFT;
+				addr2 = (pfn + PTRS_PER_PTE-1) * PAGE_SIZE +
+					PAGE_OFFSET + PAGE_SIZE-1;
+
+				if (is_x86_32_kernel_text(addr) ||
+				    is_x86_32_kernel_text(addr2))
+					prot = PAGE_KERNEL_LARGE_EXEC;
+
+				pages_2m++;
+				if (mapping_iter == 1)
+					set_pmd(pmd, pfn_pmd(pfn, init_prot));
+				else
+					set_pmd(pmd, pfn_pmd(pfn, prot));
+
+				pfn += PTRS_PER_PTE;
+				continue;
+			}
+			pte = one_page_table_init(pmd);
+
+			pte_ofs = pte_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
+			pte += pte_ofs;
+			for (; pte_ofs < PTRS_PER_PTE && pfn < end_pfn;
+			     pte++, pfn++, pte_ofs++, addr += PAGE_SIZE) {
+				pgprot_t prot = PAGE_KERNEL;
+				/*
+				 * first pass will use the same initial
+				 * identity mapping attribute.
+				 */
+				pgprot_t init_prot = __pgprot(PTE_IDENT_ATTR);
+
+				if (is_x86_32_kernel_text(addr))
+					prot = PAGE_KERNEL_EXEC;
+
+				pages_4k++;
+				if (mapping_iter == 1) {
+					set_pte(pte, pfn_pte(pfn, init_prot));
+					last_map_addr = (pfn << PAGE_SHIFT) + PAGE_SIZE;
+				} else
+					set_pte(pte, pfn_pte(pfn, prot));
+			}
+		}
+	}
+	if (mapping_iter == 1) {
+		/*
+		 * update direct mapping page count only in the first
+		 * iteration.
+		 */
+		update_page_count(PG_LEVEL_2M, pages_2m);
+		update_page_count(PG_LEVEL_4K, pages_4k);
+
+		/*
+		 * local global flush tlb, which will flush the previous
+		 * mappings present in both small and large page TLB's.
+		 */
+		__flush_tlb_all();
+
+		/*
+		 * Second iteration will set the actual desired PTE attributes.
+		 */
+		mapping_iter = 2;
+		goto repeat;
+	}
+	return last_map_addr;
+}
+
+#ifdef CONFIG_HIGHMEM
+static void __init permanent_kmaps_init(pgd_t *pgd_base)
+{
+	unsigned long vaddr = PKMAP_BASE;
+
+	page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
+
+	pkmap_page_table = virt_to_kpte(vaddr);
+}
+
+void __init add_highpages_with_active_regions(int nid,
+			 unsigned long start_pfn, unsigned long end_pfn)
+{
+	phys_addr_t start, end;
+	u64 i;
+
+	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &start, &end, NULL) {
+		unsigned long pfn = clamp_t(unsigned long, PFN_UP(start),
+					    start_pfn, end_pfn);
+		unsigned long e_pfn = clamp_t(unsigned long, PFN_DOWN(end),
+					      start_pfn, end_pfn);
+		for ( ; pfn < e_pfn; pfn++)
+			if (pfn_valid(pfn))
+				free_highmem_page(pfn_to_page(pfn));
+	}
+}
+#else
+static inline void permanent_kmaps_init(pgd_t *pgd_base)
+{
+}
+#endif /* CONFIG_HIGHMEM */
+
+void __init sync_initial_page_table(void)
+{
+	clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,
+			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
+			KERNEL_PGD_PTRS);
+
+	/*
+	 * sync back low identity map too.  It is used for example
+	 * in the 32-bit EFI stub.
+	 */
+	clone_pgd_range(initial_page_table,
+			swapper_pg_dir     + KERNEL_PGD_BOUNDARY,
+			min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
+}
+
+void __init native_pagetable_init(void)
+{
+	unsigned long pfn, va;
+	pgd_t *pgd, *base = swapper_pg_dir;
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	/*
+	 * Remove any mappings which extend past the end of physical
+	 * memory from the boot time page table.
+	 * In virtual address space, we should have at least two pages
+	 * from VMALLOC_END to pkmap or fixmap according to VMALLOC_END
+	 * definition. And max_low_pfn is set to VMALLOC_END physical
+	 * address. If initial memory mapping is doing right job, we
+	 * should have pte used near max_low_pfn or one pmd is not present.
+	 */
+	for (pfn = max_low_pfn; pfn < 1<<(32-PAGE_SHIFT); pfn++) {
+		va = PAGE_OFFSET + (pfn<<PAGE_SHIFT);
+		pgd = base + pgd_index(va);
+		if (!pgd_present(*pgd))
+			break;
+
+		p4d = p4d_offset(pgd, va);
+		pud = pud_offset(p4d, va);
+		pmd = pmd_offset(pud, va);
+		if (!pmd_present(*pmd))
+			break;
+
+		/* should not be large page here */
+		if (pmd_large(*pmd)) {
+			pr_warn("try to clear pte for ram above max_low_pfn: pfn: %lx pmd: %p pmd phys: %lx, but pmd is big page and is not using pte !\n",
+				pfn, pmd, __pa(pmd));
+			BUG_ON(1);
+		}
+
+		pte = pte_offset_kernel(pmd, va);
+		if (!pte_present(*pte))
+			break;
+
+		printk(KERN_DEBUG "clearing pte for ram above max_low_pfn: pfn: %lx pmd: %p pmd phys: %lx pte: %p pte phys: %lx\n",
+				pfn, pmd, __pa(pmd), pte, __pa(pte));
+		pte_clear(NULL, va, pte);
+	}
+	paging_init();
+}
+
+/*
+ * Build a proper pagetable for the kernel mappings.  Up until this
+ * point, we've been running on some set of pagetables constructed by
+ * the boot process.
+ *
+ * This will be a pagetable constructed in arch/x86/kernel/head_32.S.
+ * The root of the pagetable will be swapper_pg_dir.
+ *
+ * In general, pagetable_init() assumes that the pagetable may already
+ * be partially populated, and so it avoids stomping on any existing
+ * mappings.
+ */
+void __init early_ioremap_page_table_range_init(void)
+{
+	pgd_t *pgd_base = swapper_pg_dir;
+	unsigned long vaddr, end;
+
+	/*
+	 * Fixed mappings, only the page table structure has to be
+	 * created - mappings will be set by set_fixmap():
+	 */
+	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
+	end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
+	page_table_range_init(vaddr, end, pgd_base);
+	early_ioremap_reset();
+}
+
+static void __init pagetable_init(void)
+{
+	pgd_t *pgd_base = swapper_pg_dir;
+
+	permanent_kmaps_init(pgd_base);
+}
+
+#define DEFAULT_PTE_MASK ~(_PAGE_NX | _PAGE_GLOBAL)
+/* Bits supported by the hardware: */
+pteval_t __supported_pte_mask __read_mostly = DEFAULT_PTE_MASK;
+/* Bits allowed in normal kernel mappings: */
+pteval_t __default_kernel_pte_mask __read_mostly = DEFAULT_PTE_MASK;
+EXPORT_SYMBOL_GPL(__supported_pte_mask);
+/* Used in PAGE_KERNEL_* macros which are reasonably used out-of-tree: */
+EXPORT_SYMBOL(__default_kernel_pte_mask);
+
+/* user-defined highmem size */
+static unsigned int highmem_pages = -1;
+
+/*
+ * highmem=size forces highmem to be exactly 'size' bytes.
+ * This works even on boxes that have no highmem otherwise.
+ * This also works to reduce highmem size on bigger boxes.
+ */
+static int __init parse_highmem(char *arg)
+{
+	if (!arg)
+		return -EINVAL;
+
+	highmem_pages = memparse(arg, &arg) >> PAGE_SHIFT;
+	return 0;
+}
+early_param("highmem", parse_highmem);
+
+#define MSG_HIGHMEM_TOO_BIG \
+	"highmem size (%luMB) is bigger than pages available (%luMB)!\n"
+
+#define MSG_LOWMEM_TOO_SMALL \
+	"highmem size (%luMB) results in <64MB lowmem, ignoring it!\n"
+/*
+ * All of RAM fits into lowmem - but if user wants highmem
+ * artificially via the highmem=x boot parameter then create
+ * it:
+ */
+static void __init lowmem_pfn_init(void)
+{
+	/* max_low_pfn is 0, we already have early_res support */
+	max_low_pfn = max_pfn;
+
+	if (highmem_pages == -1)
+		highmem_pages = 0;
+#ifdef CONFIG_HIGHMEM
+	if (highmem_pages >= max_pfn) {
+		printk(KERN_ERR MSG_HIGHMEM_TOO_BIG,
+			pages_to_mb(highmem_pages), pages_to_mb(max_pfn));
+		highmem_pages = 0;
+	}
+	if (highmem_pages) {
+		if (max_low_pfn - highmem_pages < 64*1024*1024/PAGE_SIZE) {
+			printk(KERN_ERR MSG_LOWMEM_TOO_SMALL,
+				pages_to_mb(highmem_pages));
+			highmem_pages = 0;
+		}
+		max_low_pfn -= highmem_pages;
+	}
+#else
+	if (highmem_pages)
+		printk(KERN_ERR "ignoring highmem size on non-highmem kernel!\n");
+#endif
+}
+
+#define MSG_HIGHMEM_TOO_SMALL \
+	"only %luMB highmem pages available, ignoring highmem size of %luMB!\n"
+
+#define MSG_HIGHMEM_TRIMMED \
+	"Warning: only 4GB will be used. Use a HIGHMEM64G enabled kernel!\n"
+/*
+ * We have more RAM than fits into lowmem - we try to put it into
+ * highmem, also taking the highmem=x boot parameter into account:
+ */
+static void __init highmem_pfn_init(void)
+{
+	max_low_pfn = MAXMEM_PFN;
+
+	if (highmem_pages == -1)
+		highmem_pages = max_pfn - MAXMEM_PFN;
+
+	if (highmem_pages + MAXMEM_PFN < max_pfn)
+		max_pfn = MAXMEM_PFN + highmem_pages;
+
+	if (highmem_pages + MAXMEM_PFN > max_pfn) {
+		printk(KERN_WARNING MSG_HIGHMEM_TOO_SMALL,
+			pages_to_mb(max_pfn - MAXMEM_PFN),
+			pages_to_mb(highmem_pages));
+		highmem_pages = 0;
+	}
+#ifndef CONFIG_HIGHMEM
+	/* Maximum memory usable is what is directly addressable */
+	printk(KERN_WARNING "Warning only %ldMB will be used.\n", MAXMEM>>20);
+	if (max_pfn > MAX_NONPAE_PFN)
+		printk(KERN_WARNING "Use a HIGHMEM64G enabled kernel.\n");
+	else
+		printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
+	max_pfn = MAXMEM_PFN;
+#else /* !CONFIG_HIGHMEM */
+#ifndef CONFIG_HIGHMEM64G
+	if (max_pfn > MAX_NONPAE_PFN) {
+		max_pfn = MAX_NONPAE_PFN;
+		printk(KERN_WARNING MSG_HIGHMEM_TRIMMED);
+	}
+#endif /* !CONFIG_HIGHMEM64G */
+#endif /* !CONFIG_HIGHMEM */
+}
+
+/*
+ * Determine low and high memory ranges:
+ */
+void __init find_low_pfn_range(void)
+{
+	/* it could update max_pfn */
+
+	if (max_pfn <= MAXMEM_PFN)
+		lowmem_pfn_init();
+	else
+		highmem_pfn_init();
+}
+
+#ifndef CONFIG_NUMA
+void __init initmem_init(void)
+{
+#ifdef CONFIG_HIGHMEM
+	highstart_pfn = highend_pfn = max_pfn;
+	if (max_pfn > max_low_pfn)
+		highstart_pfn = max_low_pfn;
+	printk(KERN_NOTICE "%ldMB HIGHMEM available.\n",
+		pages_to_mb(highend_pfn - highstart_pfn));
+	high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
+#else
+	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
+#endif
+
+	memblock_set_node(0, PHYS_ADDR_MAX, &memblock.memory, 0);
+
+#ifdef CONFIG_FLATMEM
+	max_mapnr = IS_ENABLED(CONFIG_HIGHMEM) ? highend_pfn : max_low_pfn;
+#endif
+	__vmalloc_start_set = true;
+
+	printk(KERN_NOTICE "%ldMB LOWMEM available.\n",
+			pages_to_mb(max_low_pfn));
+
+	setup_bootmem_allocator();
+}
+#endif /* !CONFIG_NUMA */
+
+void __init setup_bootmem_allocator(void)
+{
+	printk(KERN_INFO "  mapped low ram: 0 - %08lx\n",
+		 max_pfn_mapped<<PAGE_SHIFT);
+	printk(KERN_INFO "  low ram: 0 - %08lx\n", max_low_pfn<<PAGE_SHIFT);
+}
+
+/*
+ * paging_init() sets up the page tables - note that the first 8MB are
+ * already mapped by head.S.
+ *
+ * This routines also unmaps the page at virtual kernel address 0, so
+ * that we can trap those pesky NULL-reference errors in the kernel.
+ */
+void __init paging_init(void)
+{
+	pagetable_init();
+
+	__flush_tlb_all();
+
+	/*
+	 * NOTE: at this point the bootmem allocator is fully available.
+	 */
+	olpc_dt_build_devicetree();
+	sparse_init();
+	zone_sizes_init();
+}
+
+/*
+ * Test if the WP bit works in supervisor mode. It isn't supported on 386's
+ * and also on some strange 486's. All 586+'s are OK. This used to involve
+ * black magic jumps to work around some nasty CPU bugs, but fortunately the
+ * switch to using exceptions got rid of all that.
+ */
+static void __init test_wp_bit(void)
+{
+	char z = 0;
+
+	printk(KERN_INFO "Checking if this processor honours the WP bit even in supervisor mode...");
+
+	__set_fixmap(FIX_WP_TEST, __pa_symbol(empty_zero_page), PAGE_KERNEL_RO);
+
+	if (copy_to_kernel_nofault((char *)fix_to_virt(FIX_WP_TEST), &z, 1)) {
+		clear_fixmap(FIX_WP_TEST);
+		printk(KERN_CONT "Ok.\n");
+		return;
+	}
+
+	printk(KERN_CONT "No.\n");
+	panic("Linux doesn't support CPUs with broken WP.");
+}
+
+void __init mem_init(void)
+{
+	pci_iommu_alloc();
+
+#ifdef CONFIG_FLATMEM
+	BUG_ON(!mem_map);
+#endif
+	/*
+	 * With CONFIG_DEBUG_PAGEALLOC initialization of highmem pages has to
+	 * be done before memblock_free_all(). Memblock use free low memory for
+	 * temporary data (see find_range_array()) and for this purpose can use
+	 * pages that was already passed to the buddy allocator, hence marked as
+	 * not accessible in the page tables when compiled with
+	 * CONFIG_DEBUG_PAGEALLOC. Otherwise order of initialization is not
+	 * important here.
+	 */
+	set_highmem_pages_init();
+
+	/* this will put all low memory onto the freelists */
+	memblock_free_all();
+
+	after_bootmem = 1;
+	x86_init.hyper.init_after_bootmem();
+
+	/*
+	 * Check boundaries twice: Some fundamental inconsistencies can
+	 * be detected at build time already.
+	 */
+#define __FIXADDR_TOP (-PAGE_SIZE)
+#ifdef CONFIG_HIGHMEM
+	BUILD_BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE	> FIXADDR_START);
+	BUILD_BUG_ON(VMALLOC_END			> PKMAP_BASE);
+#endif
+#define high_memory (-128UL << 20)
+	BUILD_BUG_ON(VMALLOC_START			>= VMALLOC_END);
+#undef high_memory
+#undef __FIXADDR_TOP
+
+#ifdef CONFIG_HIGHMEM
+	BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE	> FIXADDR_START);
+	BUG_ON(VMALLOC_END				> PKMAP_BASE);
+#endif
+	BUG_ON(VMALLOC_START				>= VMALLOC_END);
+	BUG_ON((unsigned long)high_memory		> VMALLOC_START);
+
+	test_wp_bit();
+}
+
+int kernel_set_to_readonly __read_mostly;
+
+static void mark_nxdata_nx(void)
+{
+	/*
+	 * When this called, init has already been executed and released,
+	 * so everything past _etext should be NX.
+	 */
+	unsigned long start = PFN_ALIGN(_etext);
+	/*
+	 * This comes from is_x86_32_kernel_text upper limit. Also HPAGE where used:
+	 */
+	unsigned long size = (((unsigned long)__init_end + HPAGE_SIZE) & HPAGE_MASK) - start;
+
+	if (__supported_pte_mask & _PAGE_NX)
+		printk(KERN_INFO "NX-protecting the kernel data: %luk\n", size >> 10);
+	set_memory_nx(start, size >> PAGE_SHIFT);
+}
+
+void mark_rodata_ro(void)
+{
+	unsigned long start = PFN_ALIGN(_text);
+	unsigned long size = (unsigned long)__end_rodata - start;
+
+	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
+	pr_info("Write protecting kernel text and read-only data: %luk\n",
+		size >> 10);
+
+	kernel_set_to_readonly = 1;
+
+#ifdef CONFIG_CPA_DEBUG
+	pr_info("Testing CPA: Reverting %lx-%lx\n", start, start + size);
+	set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
+
+	pr_info("Testing CPA: write protecting again\n");
+	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
+#endif
+	mark_nxdata_nx();
+	if (__supported_pte_mask & _PAGE_NX)
+		debug_checkwx();
+}
-- 
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