472 lines
12 KiB
C
472 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Debug helper to dump the current kernel pagetables of the system
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* so that we can see what the various memory ranges are set to.
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*
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* (C) Copyright 2008 Intel Corporation
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*
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* Author: Arjan van de Ven <arjan@linux.intel.com>
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*/
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#include <linux/debugfs.h>
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#include <linux/kasan.h>
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#include <linux/mm.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/seq_file.h>
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#include <linux/highmem.h>
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#include <linux/pci.h>
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#include <linux/ptdump.h>
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#include <asm/e820/types.h>
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/*
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* The dumper groups pagetable entries of the same type into one, and for
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* that it needs to keep some state when walking, and flush this state
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* when a "break" in the continuity is found.
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*/
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struct pg_state {
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struct ptdump_state ptdump;
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int level;
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pgprotval_t current_prot;
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pgprotval_t effective_prot;
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pgprotval_t prot_levels[5];
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unsigned long start_address;
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const struct addr_marker *marker;
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unsigned long lines;
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bool to_dmesg;
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bool check_wx;
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unsigned long wx_pages;
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struct seq_file *seq;
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};
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struct addr_marker {
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unsigned long start_address;
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const char *name;
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unsigned long max_lines;
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};
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/* Address space markers hints */
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#ifdef CONFIG_X86_64
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enum address_markers_idx {
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USER_SPACE_NR = 0,
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KERNEL_SPACE_NR,
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#ifdef CONFIG_MODIFY_LDT_SYSCALL
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LDT_NR,
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#endif
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LOW_KERNEL_NR,
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VMALLOC_START_NR,
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VMEMMAP_START_NR,
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#ifdef CONFIG_KASAN
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KASAN_SHADOW_START_NR,
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KASAN_SHADOW_END_NR,
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#endif
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CPU_ENTRY_AREA_NR,
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#ifdef CONFIG_X86_ESPFIX64
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ESPFIX_START_NR,
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#endif
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#ifdef CONFIG_EFI
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EFI_END_NR,
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#endif
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HIGH_KERNEL_NR,
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MODULES_VADDR_NR,
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MODULES_END_NR,
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FIXADDR_START_NR,
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END_OF_SPACE_NR,
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};
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static struct addr_marker address_markers[] = {
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[USER_SPACE_NR] = { 0, "User Space" },
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[KERNEL_SPACE_NR] = { (1UL << 63), "Kernel Space" },
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[LOW_KERNEL_NR] = { 0UL, "Low Kernel Mapping" },
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[VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
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[VMEMMAP_START_NR] = { 0UL, "Vmemmap" },
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#ifdef CONFIG_KASAN
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/*
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* These fields get initialized with the (dynamic)
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* KASAN_SHADOW_{START,END} values in pt_dump_init().
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*/
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[KASAN_SHADOW_START_NR] = { 0UL, "KASAN shadow" },
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[KASAN_SHADOW_END_NR] = { 0UL, "KASAN shadow end" },
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#endif
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#ifdef CONFIG_MODIFY_LDT_SYSCALL
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[LDT_NR] = { 0UL, "LDT remap" },
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#endif
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[CPU_ENTRY_AREA_NR] = { CPU_ENTRY_AREA_BASE,"CPU entry Area" },
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#ifdef CONFIG_X86_ESPFIX64
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[ESPFIX_START_NR] = { ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
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#endif
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#ifdef CONFIG_EFI
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[EFI_END_NR] = { EFI_VA_END, "EFI Runtime Services" },
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#endif
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[HIGH_KERNEL_NR] = { __START_KERNEL_map, "High Kernel Mapping" },
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[MODULES_VADDR_NR] = { MODULES_VADDR, "Modules" },
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[MODULES_END_NR] = { MODULES_END, "End Modules" },
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[FIXADDR_START_NR] = { FIXADDR_START, "Fixmap Area" },
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[END_OF_SPACE_NR] = { -1, NULL }
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};
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#define INIT_PGD ((pgd_t *) &init_top_pgt)
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#else /* CONFIG_X86_64 */
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enum address_markers_idx {
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USER_SPACE_NR = 0,
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KERNEL_SPACE_NR,
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VMALLOC_START_NR,
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VMALLOC_END_NR,
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#ifdef CONFIG_HIGHMEM
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PKMAP_BASE_NR,
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#endif
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#ifdef CONFIG_MODIFY_LDT_SYSCALL
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LDT_NR,
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#endif
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CPU_ENTRY_AREA_NR,
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FIXADDR_START_NR,
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END_OF_SPACE_NR,
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};
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static struct addr_marker address_markers[] = {
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[USER_SPACE_NR] = { 0, "User Space" },
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[KERNEL_SPACE_NR] = { PAGE_OFFSET, "Kernel Mapping" },
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[VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
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[VMALLOC_END_NR] = { 0UL, "vmalloc() End" },
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#ifdef CONFIG_HIGHMEM
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[PKMAP_BASE_NR] = { 0UL, "Persistent kmap() Area" },
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#endif
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#ifdef CONFIG_MODIFY_LDT_SYSCALL
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[LDT_NR] = { 0UL, "LDT remap" },
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#endif
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[CPU_ENTRY_AREA_NR] = { 0UL, "CPU entry area" },
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[FIXADDR_START_NR] = { 0UL, "Fixmap area" },
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[END_OF_SPACE_NR] = { -1, NULL }
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};
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#define INIT_PGD (swapper_pg_dir)
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#endif /* !CONFIG_X86_64 */
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/* Multipliers for offsets within the PTEs */
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#define PTE_LEVEL_MULT (PAGE_SIZE)
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#define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
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#define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
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#define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
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#define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT)
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#define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
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({ \
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if (to_dmesg) \
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printk(KERN_INFO fmt, ##args); \
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else \
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if (m) \
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seq_printf(m, fmt, ##args); \
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})
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#define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
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({ \
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if (to_dmesg) \
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printk(KERN_CONT fmt, ##args); \
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else \
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if (m) \
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seq_printf(m, fmt, ##args); \
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})
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/*
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* Print a readable form of a pgprot_t to the seq_file
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*/
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static void printk_prot(struct seq_file *m, pgprotval_t pr, int level, bool dmsg)
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{
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static const char * const level_name[] =
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{ "pgd", "p4d", "pud", "pmd", "pte" };
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if (!(pr & _PAGE_PRESENT)) {
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/* Not present */
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pt_dump_cont_printf(m, dmsg, " ");
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} else {
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if (pr & _PAGE_USER)
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pt_dump_cont_printf(m, dmsg, "USR ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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if (pr & _PAGE_RW)
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pt_dump_cont_printf(m, dmsg, "RW ");
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else
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pt_dump_cont_printf(m, dmsg, "ro ");
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if (pr & _PAGE_PWT)
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pt_dump_cont_printf(m, dmsg, "PWT ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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if (pr & _PAGE_PCD)
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pt_dump_cont_printf(m, dmsg, "PCD ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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/* Bit 7 has a different meaning on level 3 vs 4 */
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if (level <= 3 && pr & _PAGE_PSE)
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pt_dump_cont_printf(m, dmsg, "PSE ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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if ((level == 4 && pr & _PAGE_PAT) ||
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((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE))
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pt_dump_cont_printf(m, dmsg, "PAT ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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if (pr & _PAGE_GLOBAL)
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pt_dump_cont_printf(m, dmsg, "GLB ");
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else
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pt_dump_cont_printf(m, dmsg, " ");
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if (pr & _PAGE_NX)
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pt_dump_cont_printf(m, dmsg, "NX ");
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else
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pt_dump_cont_printf(m, dmsg, "x ");
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}
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pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
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}
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static void note_wx(struct pg_state *st, unsigned long addr)
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{
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unsigned long npages;
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npages = (addr - st->start_address) / PAGE_SIZE;
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#ifdef CONFIG_PCI_BIOS
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/*
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* If PCI BIOS is enabled, the PCI BIOS area is forced to WX.
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* Inform about it, but avoid the warning.
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*/
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if (pcibios_enabled && st->start_address >= PAGE_OFFSET + BIOS_BEGIN &&
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addr <= PAGE_OFFSET + BIOS_END) {
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pr_warn_once("x86/mm: PCI BIOS W+X mapping %lu pages\n", npages);
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return;
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}
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#endif
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/* Account the WX pages */
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st->wx_pages += npages;
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WARN_ONCE(__supported_pte_mask & _PAGE_NX,
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"x86/mm: Found insecure W+X mapping at address %pS\n",
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(void *)st->start_address);
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}
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static void effective_prot(struct ptdump_state *pt_st, int level, u64 val)
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{
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struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
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pgprotval_t prot = val & PTE_FLAGS_MASK;
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pgprotval_t effective;
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if (level > 0) {
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pgprotval_t higher_prot = st->prot_levels[level - 1];
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effective = (higher_prot & prot & (_PAGE_USER | _PAGE_RW)) |
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((higher_prot | prot) & _PAGE_NX);
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} else {
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effective = prot;
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}
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st->prot_levels[level] = effective;
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}
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/*
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* This function gets called on a break in a continuous series
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* of PTE entries; the next one is different so we need to
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* print what we collected so far.
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*/
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static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
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u64 val)
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{
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struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
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pgprotval_t new_prot, new_eff;
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pgprotval_t cur, eff;
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static const char units[] = "BKMGTPE";
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struct seq_file *m = st->seq;
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new_prot = val & PTE_FLAGS_MASK;
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if (!val)
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new_eff = 0;
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else
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new_eff = st->prot_levels[level];
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/*
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* If we have a "break" in the series, we need to flush the state that
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* we have now. "break" is either changing perms, levels or
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* address space marker.
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*/
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cur = st->current_prot;
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eff = st->effective_prot;
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if (st->level == -1) {
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/* First entry */
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st->current_prot = new_prot;
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st->effective_prot = new_eff;
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st->level = level;
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st->marker = address_markers;
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st->lines = 0;
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pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
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st->marker->name);
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} else if (new_prot != cur || new_eff != eff || level != st->level ||
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addr >= st->marker[1].start_address) {
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const char *unit = units;
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unsigned long delta;
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int width = sizeof(unsigned long) * 2;
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if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX))
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note_wx(st, addr);
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/*
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* Now print the actual finished series
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*/
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if (!st->marker->max_lines ||
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st->lines < st->marker->max_lines) {
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pt_dump_seq_printf(m, st->to_dmesg,
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"0x%0*lx-0x%0*lx ",
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width, st->start_address,
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width, addr);
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delta = addr - st->start_address;
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while (!(delta & 1023) && unit[1]) {
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delta >>= 10;
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unit++;
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}
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pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
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delta, *unit);
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printk_prot(m, st->current_prot, st->level,
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st->to_dmesg);
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}
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st->lines++;
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/*
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* We print markers for special areas of address space,
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* such as the start of vmalloc space etc.
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* This helps in the interpretation.
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*/
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if (addr >= st->marker[1].start_address) {
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if (st->marker->max_lines &&
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st->lines > st->marker->max_lines) {
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unsigned long nskip =
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st->lines - st->marker->max_lines;
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pt_dump_seq_printf(m, st->to_dmesg,
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"... %lu entr%s skipped ... \n",
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nskip,
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nskip == 1 ? "y" : "ies");
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}
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st->marker++;
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st->lines = 0;
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pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
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st->marker->name);
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}
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st->start_address = addr;
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st->current_prot = new_prot;
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st->effective_prot = new_eff;
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st->level = level;
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}
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}
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static void ptdump_walk_pgd_level_core(struct seq_file *m,
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struct mm_struct *mm, pgd_t *pgd,
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bool checkwx, bool dmesg)
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{
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const struct ptdump_range ptdump_ranges[] = {
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#ifdef CONFIG_X86_64
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{0, PTRS_PER_PGD * PGD_LEVEL_MULT / 2},
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{GUARD_HOLE_END_ADDR, ~0UL},
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#else
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{0, ~0UL},
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#endif
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{0, 0}
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};
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struct pg_state st = {
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.ptdump = {
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.note_page = note_page,
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.effective_prot = effective_prot,
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.range = ptdump_ranges
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},
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.level = -1,
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.to_dmesg = dmesg,
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.check_wx = checkwx,
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.seq = m
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};
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ptdump_walk_pgd(&st.ptdump, mm, pgd);
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if (!checkwx)
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return;
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if (st.wx_pages)
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pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
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st.wx_pages);
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else
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pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
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}
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void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm)
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{
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ptdump_walk_pgd_level_core(m, mm, mm->pgd, false, true);
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}
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void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
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bool user)
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{
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pgd_t *pgd = mm->pgd;
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#ifdef CONFIG_PAGE_TABLE_ISOLATION
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if (user && boot_cpu_has(X86_FEATURE_PTI))
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pgd = kernel_to_user_pgdp(pgd);
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#endif
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ptdump_walk_pgd_level_core(m, mm, pgd, false, false);
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}
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EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);
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void ptdump_walk_user_pgd_level_checkwx(void)
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{
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#ifdef CONFIG_PAGE_TABLE_ISOLATION
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pgd_t *pgd = INIT_PGD;
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if (!(__supported_pte_mask & _PAGE_NX) ||
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!boot_cpu_has(X86_FEATURE_PTI))
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return;
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pr_info("x86/mm: Checking user space page tables\n");
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pgd = kernel_to_user_pgdp(pgd);
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ptdump_walk_pgd_level_core(NULL, &init_mm, pgd, true, false);
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#endif
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}
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void ptdump_walk_pgd_level_checkwx(void)
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{
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ptdump_walk_pgd_level_core(NULL, &init_mm, INIT_PGD, true, false);
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}
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static int __init pt_dump_init(void)
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{
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/*
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* Various markers are not compile-time constants, so assign them
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* here.
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*/
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#ifdef CONFIG_X86_64
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address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET;
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address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
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address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
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#ifdef CONFIG_MODIFY_LDT_SYSCALL
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address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
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#endif
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#ifdef CONFIG_KASAN
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address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
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address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
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#endif
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#endif
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#ifdef CONFIG_X86_32
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address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
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address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
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# ifdef CONFIG_HIGHMEM
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address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
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# endif
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address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
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address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE;
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# ifdef CONFIG_MODIFY_LDT_SYSCALL
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address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
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# endif
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#endif
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return 0;
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}
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__initcall(pt_dump_init);
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