linux/arch/arm/mm/dump.c
Mark Rutland cca547e9aa ARM: 8249/1: mm: dump: don't skip regions
Currently the arm page table dumping code starts dumping page tables
from USER_PGTABLES_CEILING. This is unnecessary for skipping any entries
related to userspace as the swapper_pg_dir does not contain such
entries, and results in a couple of unfortuante side effects.

Firstly, any kernel mappings which might exist below
USER_PGTABLES_CEILING will not be accounted in the dump output. This
masks any entries erroneously created below this address.

Secondly, if the final page table entry walked is part of a valid
mapping the page table dumping code will not log the region this entry
is part of, as the final note_page call in walk_pgd will trigger an
early return when 0 < USER_PGTABLES_CEILING. Luckily this isn't seen on
contemporary systems as they typically don't have enough RAM to extend
the linear mapping right to the end of the address space.

Due to the way addr is constructed in the walk_* functions, it can never
be less than USER_PGTABLES_CEILING when walking the page tables, so it
is not necessary to avoid dereferencing invalid table addresses. The
existing checks for st->current_prot and st->marker[1].start_address are
sufficient to ensure we will not print and/or dereference garbage when
trying to log information.

This patch removes both problematic uses of USER_PGTABLES_CEILING from
the arm page table dumping code, preventing both of these issues. We
will now report any low mappings, and the final note_page call will not
return early, ensuring all regions are logged.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2015-01-07 20:33:33 +00:00

361 lines
7.8 KiB
C

/*
* 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 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/seq_file.h>
#include <asm/fixmap.h>
#include <asm/pgtable.h>
struct addr_marker {
unsigned long start_address;
const char *name;
};
static struct addr_marker address_markers[] = {
{ MODULES_VADDR, "Modules" },
{ PAGE_OFFSET, "Kernel Mapping" },
{ 0, "vmalloc() Area" },
{ VMALLOC_END, "vmalloc() End" },
{ FIXADDR_START, "Fixmap Area" },
{ CONFIG_VECTORS_BASE, "Vectors" },
{ CONFIG_VECTORS_BASE + PAGE_SIZE * 2, "Vectors End" },
{ -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 = L_PTE_USER,
.val = L_PTE_USER,
.set = "USR",
.clear = " ",
}, {
.mask = L_PTE_RDONLY,
.val = L_PTE_RDONLY,
.set = "ro",
.clear = "RW",
}, {
.mask = L_PTE_XN,
.val = L_PTE_XN,
.set = "NX",
.clear = "x ",
}, {
.mask = L_PTE_SHARED,
.val = L_PTE_SHARED,
.set = "SHD",
.clear = " ",
}, {
.mask = L_PTE_MT_MASK,
.val = L_PTE_MT_UNCACHED,
.set = "SO/UNCACHED",
}, {
.mask = L_PTE_MT_MASK,
.val = L_PTE_MT_BUFFERABLE,
.set = "MEM/BUFFERABLE/WC",
}, {
.mask = L_PTE_MT_MASK,
.val = L_PTE_MT_WRITETHROUGH,
.set = "MEM/CACHED/WT",
}, {
.mask = L_PTE_MT_MASK,
.val = L_PTE_MT_WRITEBACK,
.set = "MEM/CACHED/WBRA",
#ifndef CONFIG_ARM_LPAE
}, {
.mask = L_PTE_MT_MASK,
.val = L_PTE_MT_MINICACHE,
.set = "MEM/MINICACHE",
#endif
}, {
.mask = L_PTE_MT_MASK,
.val = L_PTE_MT_WRITEALLOC,
.set = "MEM/CACHED/WBWA",
}, {
.mask = L_PTE_MT_MASK,
.val = L_PTE_MT_DEV_SHARED,
.set = "DEV/SHARED",
#ifndef CONFIG_ARM_LPAE
}, {
.mask = L_PTE_MT_MASK,
.val = L_PTE_MT_DEV_NONSHARED,
.set = "DEV/NONSHARED",
#endif
}, {
.mask = L_PTE_MT_MASK,
.val = L_PTE_MT_DEV_WC,
.set = "DEV/WC",
}, {
.mask = L_PTE_MT_MASK,
.val = L_PTE_MT_DEV_CACHED,
.set = "DEV/CACHED",
},
};
static const struct prot_bits section_bits[] = {
#ifdef CONFIG_ARM_LPAE
{
.mask = PMD_SECT_USER,
.val = PMD_SECT_USER,
.set = "USR",
}, {
.mask = L_PMD_SECT_RDONLY,
.val = L_PMD_SECT_RDONLY,
.set = "ro",
.clear = "RW",
#elif __LINUX_ARM_ARCH__ >= 6
{
.mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_APX | PMD_SECT_AP_WRITE,
.set = " ro",
}, {
.mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_WRITE,
.set = " RW",
}, {
.mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_READ,
.set = "USR ro",
}, {
.mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.set = "USR RW",
#else /* ARMv4/ARMv5 */
/* These are approximate */
{
.mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = 0,
.set = " ro",
}, {
.mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_WRITE,
.set = " RW",
}, {
.mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_READ,
.set = "USR ro",
}, {
.mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
.set = "USR RW",
#endif
}, {
.mask = PMD_SECT_XN,
.val = PMD_SECT_XN,
.set = "NX",
.clear = "x ",
}, {
.mask = PMD_SECT_S,
.val = PMD_SECT_S,
.set = "SHD",
.clear = " ",
},
};
struct pg_level {
const struct prot_bits *bits;
size_t num;
u64 mask;
};
static struct pg_level pg_level[] = {
{
}, { /* pgd */
}, { /* pud */
}, { /* pmd */
.bits = section_bits,
.num = ARRAY_SIZE(section_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 (!st->level) {
st->level = level;
st->current_prot = prot;
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%08lx-0x%08lx ",
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_printf(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;
}
}
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_large(*pmd) || !pmd_present(*pmd))
note_page(st, addr, 3, pmd_val(*pmd));
else
walk_pte(st, pmd, addr);
if (SECTION_SIZE < PMD_SIZE && pmd_large(pmd[1]))
note_page(st, addr + SECTION_SIZE, 3, pmd_val(pmd[1]));
}
}
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)) {
walk_pmd(st, pud, addr);
} else {
note_page(st, addr, 2, pud_val(*pud));
}
}
}
static void walk_pgd(struct seq_file *m)
{
pgd_t *pgd = swapper_pg_dir;
struct pg_state st;
unsigned long addr;
unsigned i;
memset(&st, 0, sizeof(st));
st.seq = m;
st.marker = address_markers;
for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
addr = i * PGDIR_SIZE;
if (!pgd_none(*pgd)) {
walk_pud(&st, pgd, addr);
} else {
note_page(&st, addr, 1, pgd_val(*pgd));
}
}
note_page(&st, 0, 0, 0);
}
static int ptdump_show(struct seq_file *m, void *v)
{
walk_pgd(m);
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[2].start_address = VMALLOC_START;
pe = debugfs_create_file("kernel_page_tables", 0400, NULL, NULL,
&ptdump_fops);
return pe ? 0 : -ENOMEM;
}
__initcall(ptdump_init);