Commit c9465b4e authored by Laura Abbott's avatar Laura Abbott Committed by Will Deacon

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: default avatarSteve Capper <steve.capper@linaro.org>
Tested-by: default avatarSteve Capper <steve.capper@linaro.org>
Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Tested-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarLaura Abbott <lauraa@codeaurora.org>
[will: s/BUFFERABLE/NORMAL-NC/]
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent dab78b6d
......@@ -6,6 +6,18 @@ config FRAME_POINTER
bool
default y
config ARM64_PTDUMP
bool "Export kernel pagetable layout to userspace via debugfs"
depends on DEBUG_KERNEL
select DEBUG_FS
help
Say Y here if you want to show the kernel pagetable layout in a
debugfs file. This information is only useful for kernel developers
who are working in architecture specific areas of the kernel.
It is probably not a good idea to enable this feature in a production
kernel.
If in doubt, say "N"
config STRICT_DEVMEM
bool "Filter access to /dev/mem"
depends on MMU
......
......@@ -3,3 +3,4 @@ obj-y := dma-mapping.o extable.o fault.o init.o \
ioremap.o mmap.o pgd.o mmu.o \
context.o proc.o pageattr.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
obj-$(CONFIG_ARM64_PTDUMP) += dump.o
/*
* Copyright (c) 2014, The Linux Foundation. All rights reserved.
* Debug helper to dump the current kernel pagetables of the system
* so that we can see what the various memory ranges are set to.
*
* Derived from x86 and arm implementation:
* (C) Copyright 2008 Intel Corporation
*
* Author: Arjan van de Ven <arjan@linux.intel.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; version 2
* of the License.
*/
#include <linux/debugfs.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <asm/fixmap.h>
#include <asm/pgtable.h>
#define LOWEST_ADDR (UL(0xffffffffffffffff) << VA_BITS)
struct addr_marker {
unsigned long start_address;
const char *name;
};
enum address_markers_idx {
VMALLOC_START_NR = 0,
VMALLOC_END_NR,
#ifdef CONFIG_SPARSEMEM_VMEMMAP
VMEMMAP_START_NR,
VMEMMAP_END_NR,
#endif
PCI_START_NR,
PCI_END_NR,
FIXADDR_START_NR,
FIXADDR_END_NR,
MODULES_START_NR,
MODUELS_END_NR,
KERNEL_SPACE_NR,
};
static struct addr_marker address_markers[] = {
{ VMALLOC_START, "vmalloc() Area" },
{ VMALLOC_END, "vmalloc() End" },
#ifdef CONFIG_SPARSEMEM_VMEMMAP
{ 0, "vmemmap start" },
{ 0, "vmemmap end" },
#endif
{ (unsigned long) PCI_IOBASE, "PCI I/O start" },
{ (unsigned long) PCI_IOBASE + SZ_16M, "PCI I/O end" },
{ FIXADDR_START, "Fixmap start" },
{ FIXADDR_TOP, "Fixmap end" },
{ MODULES_VADDR, "Modules start" },
{ MODULES_END, "Modules end" },
{ PAGE_OFFSET, "Kernel Mapping" },
{ -1, NULL },
};
struct pg_state {
struct seq_file *seq;
const struct addr_marker *marker;
unsigned long start_address;
unsigned level;
u64 current_prot;
};
struct prot_bits {
u64 mask;
u64 val;
const char *set;
const char *clear;
};
static const struct prot_bits pte_bits[] = {
{
.mask = PTE_USER,
.val = PTE_USER,
.set = "USR",
.clear = " ",
}, {
.mask = PTE_RDONLY,
.val = PTE_RDONLY,
.set = "ro",
.clear = "RW",
}, {
.mask = PTE_PXN,
.val = PTE_PXN,
.set = "NX",
.clear = "x ",
}, {
.mask = PTE_SHARED,
.val = PTE_SHARED,
.set = "SHD",
.clear = " ",
}, {
.mask = PTE_AF,
.val = PTE_AF,
.set = "AF",
.clear = " ",
}, {
.mask = PTE_NG,
.val = PTE_NG,
.set = "NG",
.clear = " ",
}, {
.mask = PTE_UXN,
.val = PTE_UXN,
.set = "UXN",
}, {
.mask = PTE_ATTRINDX_MASK,
.val = PTE_ATTRINDX(MT_DEVICE_nGnRnE),
.set = "DEVICE/nGnRnE",
}, {
.mask = PTE_ATTRINDX_MASK,
.val = PTE_ATTRINDX(MT_DEVICE_nGnRE),
.set = "DEVICE/nGnRE",
}, {
.mask = PTE_ATTRINDX_MASK,
.val = PTE_ATTRINDX(MT_DEVICE_GRE),
.set = "DEVICE/GRE",
}, {
.mask = PTE_ATTRINDX_MASK,
.val = PTE_ATTRINDX(MT_NORMAL_NC),
.set = "MEM/NORMAL-NC",
}, {
.mask = PTE_ATTRINDX_MASK,
.val = PTE_ATTRINDX(MT_NORMAL),
.set = "MEM/NORMAL",
}
};
struct pg_level {
const struct prot_bits *bits;
size_t num;
u64 mask;
};
static struct pg_level pg_level[] = {
{
}, { /* pgd */
.bits = pte_bits,
.num = ARRAY_SIZE(pte_bits),
}, { /* pud */
.bits = pte_bits,
.num = ARRAY_SIZE(pte_bits),
}, { /* pmd */
.bits = pte_bits,
.num = ARRAY_SIZE(pte_bits),
}, { /* pte */
.bits = pte_bits,
.num = ARRAY_SIZE(pte_bits),
},
};
static void dump_prot(struct pg_state *st, const struct prot_bits *bits,
size_t num)
{
unsigned i;
for (i = 0; i < num; i++, bits++) {
const char *s;
if ((st->current_prot & bits->mask) == bits->val)
s = bits->set;
else
s = bits->clear;
if (s)
seq_printf(st->seq, " %s", s);
}
}
static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
u64 val)
{
static const char units[] = "KMGTPE";
u64 prot = val & pg_level[level].mask;
if (addr < LOWEST_ADDR)
return;
if (!st->level) {
st->level = level;
st->current_prot = prot;
st->start_address = addr;
seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
} else if (prot != st->current_prot || level != st->level ||
addr >= st->marker[1].start_address) {
const char *unit = units;
unsigned long delta;
if (st->current_prot) {
seq_printf(st->seq, "0x%16lx-0x%16lx ",
st->start_address, addr);
delta = (addr - st->start_address) >> 10;
while (!(delta & 1023) && unit[1]) {
delta >>= 10;
unit++;
}
seq_printf(st->seq, "%9lu%c", delta, *unit);
if (pg_level[st->level].bits)
dump_prot(st, pg_level[st->level].bits,
pg_level[st->level].num);
seq_puts(st->seq, "\n");
}
if (addr >= st->marker[1].start_address) {
st->marker++;
seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
}
st->start_address = addr;
st->current_prot = prot;
st->level = level;
}
if (addr >= st->marker[1].start_address) {
st->marker++;
seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
}
}
static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
{
pte_t *pte = pte_offset_kernel(pmd, 0);
unsigned long addr;
unsigned i;
for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
addr = start + i * PAGE_SIZE;
note_page(st, addr, 4, pte_val(*pte));
}
}
static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
{
pmd_t *pmd = pmd_offset(pud, 0);
unsigned long addr;
unsigned i;
for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
addr = start + i * PMD_SIZE;
if (pmd_none(*pmd) || pmd_sect(*pmd) || pmd_bad(*pmd))
note_page(st, addr, 3, pmd_val(*pmd));
else
walk_pte(st, pmd, addr);
}
}
static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
{
pud_t *pud = pud_offset(pgd, 0);
unsigned long addr;
unsigned i;
for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
addr = start + i * PUD_SIZE;
if (pud_none(*pud) || pud_sect(*pud) || pud_bad(*pud))
note_page(st, addr, 2, pud_val(*pud));
else
walk_pmd(st, pud, addr);
}
}
static void walk_pgd(struct pg_state *st, struct mm_struct *mm, unsigned long start)
{
pgd_t *pgd = pgd_offset(mm, 0);
unsigned i;
unsigned long addr;
for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
addr = start + i * PGDIR_SIZE;
if (pgd_none(*pgd) || pgd_bad(*pgd))
note_page(st, addr, 1, pgd_val(*pgd));
else
walk_pud(st, pgd, addr);
}
}
static int ptdump_show(struct seq_file *m, void *v)
{
struct pg_state st = {
.seq = m,
.marker = address_markers,
};
walk_pgd(&st, &init_mm, LOWEST_ADDR);
note_page(&st, 0, 0, 0);
return 0;
}
static int ptdump_open(struct inode *inode, struct file *file)
{
return single_open(file, ptdump_show, NULL);
}
static const struct file_operations ptdump_fops = {
.open = ptdump_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int ptdump_init(void)
{
struct dentry *pe;
unsigned i, j;
for (i = 0; i < ARRAY_SIZE(pg_level); i++)
if (pg_level[i].bits)
for (j = 0; j < pg_level[i].num; j++)
pg_level[i].mask |= pg_level[i].bits[j].mask;
address_markers[VMEMMAP_START_NR].start_address =
(unsigned long)virt_to_page(PAGE_OFFSET);
address_markers[VMEMMAP_END_NR].start_address =
(unsigned long)virt_to_page(high_memory);
pe = debugfs_create_file("kernel_page_tables", 0400, NULL, NULL,
&ptdump_fops);
return pe ? 0 : -ENOMEM;
}
device_initcall(ptdump_init);
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