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475 lines
10 KiB
475 lines
10 KiB
// 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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* Derived from x86 implementation: |
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* (C) Copyright 2008 Intel Corporation |
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* |
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* Author: Arjan van de Ven <[email protected]> |
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*/ |
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#include <linux/debugfs.h> |
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#include <linux/fs.h> |
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#include <linux/mm.h> |
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#include <linux/seq_file.h> |
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#include <asm/domain.h> |
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#include <asm/fixmap.h> |
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#include <asm/memory.h> |
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#include <asm/ptdump.h> |
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static struct addr_marker address_markers[] = { |
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#ifdef CONFIG_KASAN |
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{ KASAN_SHADOW_START, "Kasan shadow start"}, |
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{ KASAN_SHADOW_END, "Kasan shadow end"}, |
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#endif |
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{ MODULES_VADDR, "Modules" }, |
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{ PAGE_OFFSET, "Kernel Mapping" }, |
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{ 0, "vmalloc() Area" }, |
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{ VMALLOC_END, "vmalloc() End" }, |
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{ FIXADDR_START, "Fixmap Area" }, |
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{ VECTORS_BASE, "Vectors" }, |
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{ VECTORS_BASE + PAGE_SIZE * 2, "Vectors End" }, |
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{ -1, NULL }, |
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}; |
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#define pt_dump_seq_printf(m, fmt, args...) \ |
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({ \ |
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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_seq_puts(m, fmt) \ |
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({ \ |
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if (m) \ |
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seq_printf(m, fmt); \ |
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}) |
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struct pg_state { |
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struct seq_file *seq; |
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const struct addr_marker *marker; |
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unsigned long start_address; |
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unsigned level; |
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u64 current_prot; |
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bool check_wx; |
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unsigned long wx_pages; |
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const char *current_domain; |
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}; |
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struct prot_bits { |
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u64 mask; |
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u64 val; |
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const char *set; |
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const char *clear; |
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bool ro_bit; |
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bool nx_bit; |
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}; |
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static const struct prot_bits pte_bits[] = { |
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{ |
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.mask = L_PTE_USER, |
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.val = L_PTE_USER, |
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.set = "USR", |
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.clear = " ", |
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}, { |
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.mask = L_PTE_RDONLY, |
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.val = L_PTE_RDONLY, |
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.set = "ro", |
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.clear = "RW", |
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.ro_bit = true, |
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}, { |
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.mask = L_PTE_XN, |
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.val = L_PTE_XN, |
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.set = "NX", |
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.clear = "x ", |
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.nx_bit = true, |
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}, { |
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.mask = L_PTE_SHARED, |
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.val = L_PTE_SHARED, |
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.set = "SHD", |
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.clear = " ", |
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}, { |
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.mask = L_PTE_MT_MASK, |
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.val = L_PTE_MT_UNCACHED, |
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.set = "SO/UNCACHED", |
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}, { |
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.mask = L_PTE_MT_MASK, |
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.val = L_PTE_MT_BUFFERABLE, |
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.set = "MEM/BUFFERABLE/WC", |
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}, { |
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.mask = L_PTE_MT_MASK, |
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.val = L_PTE_MT_WRITETHROUGH, |
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.set = "MEM/CACHED/WT", |
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}, { |
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.mask = L_PTE_MT_MASK, |
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.val = L_PTE_MT_WRITEBACK, |
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.set = "MEM/CACHED/WBRA", |
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#ifndef CONFIG_ARM_LPAE |
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}, { |
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.mask = L_PTE_MT_MASK, |
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.val = L_PTE_MT_MINICACHE, |
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.set = "MEM/MINICACHE", |
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#endif |
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}, { |
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.mask = L_PTE_MT_MASK, |
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.val = L_PTE_MT_WRITEALLOC, |
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.set = "MEM/CACHED/WBWA", |
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}, { |
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.mask = L_PTE_MT_MASK, |
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.val = L_PTE_MT_DEV_SHARED, |
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.set = "DEV/SHARED", |
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#ifndef CONFIG_ARM_LPAE |
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}, { |
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.mask = L_PTE_MT_MASK, |
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.val = L_PTE_MT_DEV_NONSHARED, |
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.set = "DEV/NONSHARED", |
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#endif |
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}, { |
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.mask = L_PTE_MT_MASK, |
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.val = L_PTE_MT_DEV_WC, |
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.set = "DEV/WC", |
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}, { |
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.mask = L_PTE_MT_MASK, |
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.val = L_PTE_MT_DEV_CACHED, |
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.set = "DEV/CACHED", |
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}, |
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}; |
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static const struct prot_bits section_bits[] = { |
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#ifdef CONFIG_ARM_LPAE |
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{ |
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.mask = PMD_SECT_USER, |
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.val = PMD_SECT_USER, |
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.set = "USR", |
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}, { |
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.mask = L_PMD_SECT_RDONLY | PMD_SECT_AP2, |
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.val = L_PMD_SECT_RDONLY | PMD_SECT_AP2, |
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.set = "ro", |
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.clear = "RW", |
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.ro_bit = true, |
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#elif __LINUX_ARM_ARCH__ >= 6 |
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{ |
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.mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
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.val = PMD_SECT_APX | PMD_SECT_AP_WRITE, |
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.set = " ro", |
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.ro_bit = true, |
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}, { |
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.mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
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.val = PMD_SECT_AP_WRITE, |
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.set = " RW", |
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}, { |
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.mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
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.val = PMD_SECT_AP_READ, |
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.set = "USR ro", |
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}, { |
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.mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
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.val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
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.set = "USR RW", |
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#else /* ARMv4/ARMv5 */ |
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/* These are approximate */ |
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{ |
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.mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
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.val = 0, |
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.set = " ro", |
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.ro_bit = true, |
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}, { |
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.mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
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.val = PMD_SECT_AP_WRITE, |
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.set = " RW", |
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}, { |
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.mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
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.val = PMD_SECT_AP_READ, |
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.set = "USR ro", |
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}, { |
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.mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
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.val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
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.set = "USR RW", |
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#endif |
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}, { |
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.mask = PMD_SECT_XN, |
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.val = PMD_SECT_XN, |
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.set = "NX", |
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.clear = "x ", |
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.nx_bit = true, |
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}, { |
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.mask = PMD_SECT_S, |
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.val = PMD_SECT_S, |
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.set = "SHD", |
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.clear = " ", |
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}, |
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}; |
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struct pg_level { |
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const struct prot_bits *bits; |
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size_t num; |
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u64 mask; |
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const struct prot_bits *ro_bit; |
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const struct prot_bits *nx_bit; |
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}; |
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static struct pg_level pg_level[] = { |
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{ |
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}, { /* pgd */ |
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}, { /* p4d */ |
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}, { /* pud */ |
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}, { /* pmd */ |
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.bits = section_bits, |
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.num = ARRAY_SIZE(section_bits), |
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}, { /* pte */ |
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.bits = pte_bits, |
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.num = ARRAY_SIZE(pte_bits), |
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}, |
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}; |
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static void dump_prot(struct pg_state *st, const struct prot_bits *bits, size_t num) |
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{ |
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unsigned i; |
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for (i = 0; i < num; i++, bits++) { |
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const char *s; |
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if ((st->current_prot & bits->mask) == bits->val) |
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s = bits->set; |
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else |
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s = bits->clear; |
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if (s) |
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pt_dump_seq_printf(st->seq, " %s", s); |
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} |
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} |
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static void note_prot_wx(struct pg_state *st, unsigned long addr) |
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{ |
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if (!st->check_wx) |
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return; |
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if ((st->current_prot & pg_level[st->level].ro_bit->mask) == |
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pg_level[st->level].ro_bit->val) |
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return; |
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if ((st->current_prot & pg_level[st->level].nx_bit->mask) == |
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pg_level[st->level].nx_bit->val) |
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return; |
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WARN_ONCE(1, "arm/mm: Found insecure W+X mapping at address %pS\n", |
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(void *)st->start_address); |
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st->wx_pages += (addr - st->start_address) / PAGE_SIZE; |
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} |
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static void note_page(struct pg_state *st, unsigned long addr, |
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unsigned int level, u64 val, const char *domain) |
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{ |
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static const char units[] = "KMGTPE"; |
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u64 prot = val & pg_level[level].mask; |
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if (!st->level) { |
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st->level = level; |
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st->current_prot = prot; |
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st->current_domain = domain; |
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pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); |
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} else if (prot != st->current_prot || level != st->level || |
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domain != st->current_domain || |
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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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if (st->current_prot) { |
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note_prot_wx(st, addr); |
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pt_dump_seq_printf(st->seq, "0x%08lx-0x%08lx ", |
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st->start_address, addr); |
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delta = (addr - st->start_address) >> 10; |
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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_seq_printf(st->seq, "%9lu%c", delta, *unit); |
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if (st->current_domain) |
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pt_dump_seq_printf(st->seq, " %s", |
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st->current_domain); |
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if (pg_level[st->level].bits) |
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dump_prot(st, pg_level[st->level].bits, pg_level[st->level].num); |
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pt_dump_seq_printf(st->seq, "\n"); |
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} |
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if (addr >= st->marker[1].start_address) { |
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st->marker++; |
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pt_dump_seq_printf(st->seq, "---[ %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 = prot; |
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st->current_domain = domain; |
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st->level = level; |
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} |
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} |
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static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start, |
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const char *domain) |
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{ |
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pte_t *pte = pte_offset_kernel(pmd, 0); |
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unsigned long addr; |
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unsigned i; |
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for (i = 0; i < PTRS_PER_PTE; i++, pte++) { |
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addr = start + i * PAGE_SIZE; |
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note_page(st, addr, 5, pte_val(*pte), domain); |
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} |
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} |
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static const char *get_domain_name(pmd_t *pmd) |
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{ |
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#ifndef CONFIG_ARM_LPAE |
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switch (pmd_val(*pmd) & PMD_DOMAIN_MASK) { |
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case PMD_DOMAIN(DOMAIN_KERNEL): |
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return "KERNEL "; |
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case PMD_DOMAIN(DOMAIN_USER): |
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return "USER "; |
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case PMD_DOMAIN(DOMAIN_IO): |
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return "IO "; |
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case PMD_DOMAIN(DOMAIN_VECTORS): |
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return "VECTORS"; |
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default: |
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return "unknown"; |
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} |
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#endif |
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return NULL; |
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} |
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static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start) |
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{ |
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pmd_t *pmd = pmd_offset(pud, 0); |
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unsigned long addr; |
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unsigned i; |
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const char *domain; |
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for (i = 0; i < PTRS_PER_PMD; i++, pmd++) { |
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addr = start + i * PMD_SIZE; |
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domain = get_domain_name(pmd); |
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if (pmd_none(*pmd) || pmd_large(*pmd) || !pmd_present(*pmd)) |
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note_page(st, addr, 3, pmd_val(*pmd), domain); |
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else |
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walk_pte(st, pmd, addr, domain); |
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if (SECTION_SIZE < PMD_SIZE && pmd_large(pmd[1])) { |
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addr += SECTION_SIZE; |
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pmd++; |
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domain = get_domain_name(pmd); |
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note_page(st, addr, 4, pmd_val(*pmd), domain); |
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} |
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} |
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} |
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static void walk_pud(struct pg_state *st, p4d_t *p4d, unsigned long start) |
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{ |
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pud_t *pud = pud_offset(p4d, 0); |
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unsigned long addr; |
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unsigned i; |
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for (i = 0; i < PTRS_PER_PUD; i++, pud++) { |
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addr = start + i * PUD_SIZE; |
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if (!pud_none(*pud)) { |
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walk_pmd(st, pud, addr); |
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} else { |
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note_page(st, addr, 3, pud_val(*pud), NULL); |
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} |
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} |
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} |
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static void walk_p4d(struct pg_state *st, pgd_t *pgd, unsigned long start) |
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{ |
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p4d_t *p4d = p4d_offset(pgd, 0); |
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unsigned long addr; |
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unsigned i; |
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for (i = 0; i < PTRS_PER_P4D; i++, p4d++) { |
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addr = start + i * P4D_SIZE; |
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if (!p4d_none(*p4d)) { |
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walk_pud(st, p4d, addr); |
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} else { |
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note_page(st, addr, 2, p4d_val(*p4d), NULL); |
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} |
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} |
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} |
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static void walk_pgd(struct pg_state *st, struct mm_struct *mm, |
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unsigned long start) |
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{ |
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pgd_t *pgd = pgd_offset(mm, 0UL); |
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unsigned i; |
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unsigned long addr; |
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for (i = 0; i < PTRS_PER_PGD; i++, pgd++) { |
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addr = start + i * PGDIR_SIZE; |
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if (!pgd_none(*pgd)) { |
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walk_p4d(st, pgd, addr); |
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} else { |
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note_page(st, addr, 1, pgd_val(*pgd), NULL); |
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} |
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} |
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} |
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void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info) |
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{ |
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struct pg_state st = { |
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.seq = m, |
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.marker = info->markers, |
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.check_wx = false, |
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}; |
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walk_pgd(&st, info->mm, info->base_addr); |
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note_page(&st, 0, 0, 0, NULL); |
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} |
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static void ptdump_initialize(void) |
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{ |
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unsigned i, j; |
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for (i = 0; i < ARRAY_SIZE(pg_level); i++) |
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if (pg_level[i].bits) |
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for (j = 0; j < pg_level[i].num; j++) { |
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pg_level[i].mask |= pg_level[i].bits[j].mask; |
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if (pg_level[i].bits[j].ro_bit) |
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pg_level[i].ro_bit = &pg_level[i].bits[j]; |
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if (pg_level[i].bits[j].nx_bit) |
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pg_level[i].nx_bit = &pg_level[i].bits[j]; |
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} |
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#ifdef CONFIG_KASAN |
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address_markers[4].start_address = VMALLOC_START; |
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#else |
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address_markers[2].start_address = VMALLOC_START; |
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#endif |
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} |
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static struct ptdump_info kernel_ptdump_info = { |
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.mm = &init_mm, |
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.markers = address_markers, |
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.base_addr = 0, |
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}; |
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void ptdump_check_wx(void) |
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{ |
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struct pg_state st = { |
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.seq = NULL, |
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.marker = (struct addr_marker[]) { |
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{ 0, NULL}, |
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{ -1, NULL}, |
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}, |
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.check_wx = true, |
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}; |
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walk_pgd(&st, &init_mm, 0); |
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note_page(&st, 0, 0, 0, NULL); |
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if (st.wx_pages) |
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pr_warn("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("Checked W+X mappings: passed, no W+X pages found\n"); |
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} |
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static int ptdump_init(void) |
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{ |
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ptdump_initialize(); |
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ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables"); |
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return 0; |
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} |
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__initcall(ptdump_init);
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