linux/arch/arm/mm/dump.c
Steven Capper ded9477984 ARM: 8109/1: mm: Modify pte_write and pmd_write logic for LPAE
For LPAE, we have the following means for encoding writable or dirty
ptes:
                              L_PTE_DIRTY       L_PTE_RDONLY
    !pte_dirty && !pte_write        0               1
    !pte_dirty && pte_write         0               1
    pte_dirty && !pte_write         1               1
    pte_dirty && pte_write          1               0

So we can't distinguish between writeable clean ptes and read only
ptes. This can cause problems with ptes being incorrectly flagged as
read only when they are writeable but not dirty.

This patch renumbers L_PTE_RDONLY from AP[2] to a software bit #58,
and adds additional logic to set AP[2] whenever the pte is read only
or not dirty. That way we can distinguish between clean writeable ptes
and read only ptes.

HugeTLB pages will use this new logic automatically.

We need to add some logic to Transparent HugePages to ensure that they
correctly interpret the revised pgprot permissions (L_PTE_RDONLY has
moved and no longer matches PMD_SECT_AP2). In the process of revising
THP, the names of the PMD software bits have been prefixed with L_ to
make them easier to distinguish from their hardware bit counterparts.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-07-24 14:27:08 +01:00

366 lines
7.9 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 (addr < USER_PGTABLES_CEILING)
return;
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, pgdoff = USER_PGTABLES_CEILING / PGDIR_SIZE;
memset(&st, 0, sizeof(st));
st.seq = m;
st.marker = address_markers;
pgd += pgdoff;
for (i = pgdoff; 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);