arm64: add support to dump the kernel page tables
In a similar manner to arm, it's useful to be able to dump the page tables to verify permissions and memory types. Add a debugfs file to check the page tables. Acked-by: Steve Capper <steve.capper@linaro.org> Tested-by: Steve Capper <steve.capper@linaro.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Laura Abbott <lauraa@codeaurora.org> [will: s/BUFFERABLE/NORMAL-NC/] Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Laura Abbott
Will Deacon
parent
dab78b6dcb
commit
c9465b4ec3
3 changed files with 345 additions and 0 deletions
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@ -6,6 +6,18 @@ config FRAME_POINTER
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bool
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default y
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config ARM64_PTDUMP
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bool "Export kernel pagetable layout to userspace via debugfs"
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depends on DEBUG_KERNEL
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select DEBUG_FS
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help
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Say Y here if you want to show the kernel pagetable layout in a
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debugfs file. This information is only useful for kernel developers
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who are working in architecture specific areas of the kernel.
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It is probably not a good idea to enable this feature in a production
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kernel.
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If in doubt, say "N"
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config STRICT_DEVMEM
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bool "Filter access to /dev/mem"
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depends on MMU
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@ -3,3 +3,4 @@ obj-y := dma-mapping.o extable.o fault.o init.o \
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ioremap.o mmap.o pgd.o mmu.o \
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context.o proc.o pageattr.o
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obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
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obj-$(CONFIG_ARM64_PTDUMP) += dump.o
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332
arch/arm64/mm/dump.c
Normal file
332
arch/arm64/mm/dump.c
Normal file
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@ -0,0 +1,332 @@
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/*
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* Copyright (c) 2014, The Linux Foundation. All rights reserved.
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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 and arm implementation:
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; version 2
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* of the License.
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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/sched.h>
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#include <linux/seq_file.h>
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#include <asm/fixmap.h>
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#include <asm/pgtable.h>
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#define LOWEST_ADDR (UL(0xffffffffffffffff) << VA_BITS)
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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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};
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enum address_markers_idx {
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VMALLOC_START_NR = 0,
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VMALLOC_END_NR,
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#ifdef CONFIG_SPARSEMEM_VMEMMAP
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VMEMMAP_START_NR,
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VMEMMAP_END_NR,
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#endif
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PCI_START_NR,
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PCI_END_NR,
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FIXADDR_START_NR,
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FIXADDR_END_NR,
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MODULES_START_NR,
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MODUELS_END_NR,
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KERNEL_SPACE_NR,
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};
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static struct addr_marker address_markers[] = {
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{ VMALLOC_START, "vmalloc() Area" },
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{ VMALLOC_END, "vmalloc() End" },
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#ifdef CONFIG_SPARSEMEM_VMEMMAP
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{ 0, "vmemmap start" },
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{ 0, "vmemmap end" },
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#endif
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{ (unsigned long) PCI_IOBASE, "PCI I/O start" },
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{ (unsigned long) PCI_IOBASE + SZ_16M, "PCI I/O end" },
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{ FIXADDR_START, "Fixmap start" },
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{ FIXADDR_TOP, "Fixmap end" },
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{ MODULES_VADDR, "Modules start" },
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{ MODULES_END, "Modules end" },
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{ PAGE_OFFSET, "Kernel Mapping" },
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{ -1, NULL },
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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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};
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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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};
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static const struct prot_bits pte_bits[] = {
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{
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.mask = PTE_USER,
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.val = PTE_USER,
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.set = "USR",
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.clear = " ",
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}, {
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.mask = PTE_RDONLY,
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.val = PTE_RDONLY,
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.set = "ro",
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.clear = "RW",
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}, {
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.mask = PTE_PXN,
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.val = PTE_PXN,
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.set = "NX",
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.clear = "x ",
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}, {
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.mask = PTE_SHARED,
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.val = PTE_SHARED,
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.set = "SHD",
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.clear = " ",
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}, {
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.mask = PTE_AF,
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.val = PTE_AF,
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.set = "AF",
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.clear = " ",
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}, {
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.mask = PTE_NG,
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.val = PTE_NG,
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.set = "NG",
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.clear = " ",
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}, {
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.mask = PTE_UXN,
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.val = PTE_UXN,
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.set = "UXN",
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}, {
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.mask = PTE_ATTRINDX_MASK,
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.val = PTE_ATTRINDX(MT_DEVICE_nGnRnE),
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.set = "DEVICE/nGnRnE",
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}, {
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.mask = PTE_ATTRINDX_MASK,
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.val = PTE_ATTRINDX(MT_DEVICE_nGnRE),
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.set = "DEVICE/nGnRE",
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}, {
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.mask = PTE_ATTRINDX_MASK,
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.val = PTE_ATTRINDX(MT_DEVICE_GRE),
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.set = "DEVICE/GRE",
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}, {
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.mask = PTE_ATTRINDX_MASK,
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.val = PTE_ATTRINDX(MT_NORMAL_NC),
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.set = "MEM/NORMAL-NC",
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}, {
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.mask = PTE_ATTRINDX_MASK,
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.val = PTE_ATTRINDX(MT_NORMAL),
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.set = "MEM/NORMAL",
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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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};
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static struct pg_level pg_level[] = {
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{
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}, { /* pgd */
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.bits = pte_bits,
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.num = ARRAY_SIZE(pte_bits),
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}, { /* pud */
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.bits = pte_bits,
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.num = ARRAY_SIZE(pte_bits),
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}, { /* pmd */
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.bits = pte_bits,
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.num = ARRAY_SIZE(pte_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,
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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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seq_printf(st->seq, " %s", s);
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}
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}
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static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
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u64 val)
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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 (addr < LOWEST_ADDR)
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return;
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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->start_address = addr;
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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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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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seq_printf(st->seq, "0x%16lx-0x%16lx ",
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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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seq_printf(st->seq, "%9lu%c", delta, *unit);
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if (pg_level[st->level].bits)
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dump_prot(st, pg_level[st->level].bits,
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pg_level[st->level].num);
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seq_puts(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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seq_printf(st->seq, "---[ %s ]---\n", 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->level = level;
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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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seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
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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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{
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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, 4, pte_val(*pte));
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}
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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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for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
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addr = start + i * PMD_SIZE;
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if (pmd_none(*pmd) || pmd_sect(*pmd) || pmd_bad(*pmd))
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note_page(st, addr, 3, pmd_val(*pmd));
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else
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walk_pte(st, pmd, addr);
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}
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}
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static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
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{
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pud_t *pud = pud_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_PUD; i++, pud++) {
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addr = start + i * PUD_SIZE;
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if (pud_none(*pud) || pud_sect(*pud) || pud_bad(*pud))
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note_page(st, addr, 2, pud_val(*pud));
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else
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walk_pmd(st, pud, addr);
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}
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}
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static void walk_pgd(struct pg_state *st, struct mm_struct *mm, unsigned long start)
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{
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pgd_t *pgd = pgd_offset(mm, 0);
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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) || pgd_bad(*pgd))
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note_page(st, addr, 1, pgd_val(*pgd));
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else
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walk_pud(st, pgd, addr);
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}
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}
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static int ptdump_show(struct seq_file *m, void *v)
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{
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struct pg_state st = {
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.seq = m,
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.marker = address_markers,
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};
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walk_pgd(&st, &init_mm, LOWEST_ADDR);
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note_page(&st, 0, 0, 0);
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return 0;
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}
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static int ptdump_open(struct inode *inode, struct file *file)
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{
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return single_open(file, ptdump_show, NULL);
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}
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static const struct file_operations ptdump_fops = {
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.open = ptdump_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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static int ptdump_init(void)
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{
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struct dentry *pe;
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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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address_markers[VMEMMAP_START_NR].start_address =
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(unsigned long)virt_to_page(PAGE_OFFSET);
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address_markers[VMEMMAP_END_NR].start_address =
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(unsigned long)virt_to_page(high_memory);
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pe = debugfs_create_file("kernel_page_tables", 0400, NULL, NULL,
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&ptdump_fops);
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return pe ? 0 : -ENOMEM;
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}
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device_initcall(ptdump_init);
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