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/*
* Debug helper to dump the current kernel pagetables of the system
* so that we can see what the various memory ranges are set to.
*
* (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/module.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <asm/pgtable.h>
/*
* The dumper groups pagetable entries of the same type into one, and for
* that it needs to keep some state when walking, and flush this state
* when a "break" in the continuity is found.
*/
struct pg_state {
int level;
pgprot_t current_prot;
unsigned long start_address;
unsigned long current_address;
int printed_vmalloc;
int printed_modules;
int printed_vmemmap;
int printed_highmap;
};
/* Multipliers for offsets within the PTEs */
#define LEVEL_4_MULT (PAGE_SIZE)
#define LEVEL_3_MULT (512UL * LEVEL_4_MULT)
#define LEVEL_2_MULT (512UL * LEVEL_3_MULT)
#define LEVEL_1_MULT (512UL * LEVEL_2_MULT)
/*
* Print a readable form of a pgprot_t to the seq_file
*/
static void printk_prot(struct seq_file *m, pgprot_t prot, int level)
{
unsigned long pr = pgprot_val(prot);
if (pr & _PAGE_USER)
seq_printf(m, "USR ");
else
seq_printf(m, " ");
if (pr & _PAGE_RW)
seq_printf(m, "RW ");
else
seq_printf(m, "ro ");
if (pr & _PAGE_PWT)
seq_printf(m, "PWT ");
else
seq_printf(m, " ");
if (pr & _PAGE_PCD)
seq_printf(m, "PCD ");
else
seq_printf(m, " ");
/* Bit 9 has a different meaning on level 3 vs 4 */
if (level <= 3) {
if (pr & _PAGE_PSE)
seq_printf(m, "PSE ");
else
seq_printf(m, " ");
} else {
if (pr & _PAGE_PAT)
seq_printf(m, "pat ");
else
seq_printf(m, " ");
}
if (pr & _PAGE_GLOBAL)
seq_printf(m, "GLB ");
else
seq_printf(m, " ");
if (pr & _PAGE_NX)
seq_printf(m, "NX ");
else
seq_printf(m, "x ");
}
/*
* Sign-extend the 48 bit address to 64 bit
*/
static unsigned long sign_extend(unsigned long u)
{
if (u>>47)
u = u | (0xffffUL << 48);
return u;
}
/*
* This function gets called on a break in a continuous series
* of PTE entries; the next one is different so we need to
* print what we collected so far.
*/
static void note_page(struct seq_file *m, struct pg_state *st,
pgprot_t new_prot, int level)
{
unsigned long prot, cur;
/*
* If we have a "break" in the series, we need to flush the state that
* we have now. "break" is either changing perms or a different level.
*/
prot = pgprot_val(new_prot) & ~(PTE_MASK);
cur = pgprot_val(st->current_prot) & ~(PTE_MASK);
if ((prot != cur || level != st->level) &&
st->current_address != st->start_address) {
char unit = 'K';
unsigned long delta;
/*
* We print markers for special areas of address space,
* such as the start of vmalloc space etc.
* This helps in the interpretation.
*/
if (!st->printed_vmalloc &&
st->start_address >= VMALLOC_START) {
seq_printf(m, "---[ VMALLOC SPACE ]---\n");
st->printed_vmalloc = 1;
}
if (!st->printed_modules &&
st->start_address >= MODULES_VADDR) {
seq_printf(m, "---[ MODULES SPACE ]---\n");
st->printed_modules = 1;
}
if (st->printed_modules < 2 &&
st->start_address >= MODULES_END) {
seq_printf(m, "---[ END MODULES SPACE ]---\n");
st->printed_modules = 2;
}
if (!st->printed_vmemmap &&
st->start_address >= VMEMMAP_START) {
seq_printf(m, "---[ VMMEMMAP SPACE ]---\n");
st->printed_vmemmap = 1;
}
if (!st->printed_highmap &&
st->start_address >= __START_KERNEL_map) {
seq_printf(m, "---[ HIGH KERNEL MAPPING ]---\n");
st->printed_highmap = 1;
}
/*
* Now print the actual finished series
*/
seq_printf(m, "[ %016lx - %016lx ",
st->start_address, st->current_address);
delta = (st->current_address - st->start_address) >> 10;
if ((delta & 1023) == 0) {
delta = delta >> 10;
unit = 'M';
}
if (pgprot_val(st->current_prot)) {
seq_printf(m, "Size %9lu%cb ", delta, unit);
printk_prot(m, st->current_prot, st->level);
seq_printf(m, "L%i]\n", st->level);
} else {
/* don't print protections on non-present memory */
seq_printf(m, "%14lu%cb", delta, unit);
seq_printf(m, " L%i]\n",
st->level);
}
st->start_address = st->current_address;
st->current_prot = new_prot;
st->level = level;
};
}
static void walk_level_4(struct seq_file *m, struct pg_state *st, pmd_t addr,
unsigned long P)
{
int i;
pte_t *start;
start = (pte_t *) pmd_page_vaddr(addr);
for (i = 0; i < PTRS_PER_PTE; i++) {
pgprot_t prot = pte_pgprot(*start);
st->current_address = sign_extend(P + i * LEVEL_4_MULT);
note_page(m, st, prot, 4);
start++;
}
}
static void walk_level_3(struct seq_file *m, struct pg_state *st, pud_t addr,
unsigned long P)
{
int i;
pmd_t *start;
start = (pmd_t *) pud_page_vaddr(addr);
for (i = 0; i < PTRS_PER_PMD; i++) {
st->current_address = sign_extend(P + i * LEVEL_3_MULT);
if (!pmd_none(*start)) {
unsigned long prot;
prot = pmd_val(*start) & ~(PTE_MASK);
/* Deal with 2Mb pages */
if (pmd_large(*start))
note_page(m, st, __pgprot(prot), 3);
else
walk_level_4(m, st, *start,
P + i * LEVEL_3_MULT);
} else
note_page(m, st, __pgprot(0), 3);
start++;
}
}
static void walk_level_2(struct seq_file *m, struct pg_state *st, pgd_t addr,
unsigned long P)
{
int i;
pud_t *start;
start = (pud_t *) pgd_page_vaddr(addr);
for (i = 0; i < PTRS_PER_PUD; i++) {
if (!pud_none(*start)) {
unsigned long prot;
prot = pud_val(*start) & ~(PTE_MASK);
/* Deal with 1Gb pages */
if (pud_large(*start))
note_page(m, st, __pgprot(prot), 2);
else
walk_level_3(m, st, *start,
P + i * LEVEL_2_MULT);
} else
note_page(m, st, __pgprot(0), 2);
start++;
}
}
static void walk_level_1(struct seq_file *m)
{
pgd_t *start = (pgd_t *) &init_level4_pgt;
int i;
struct pg_state st;
memset(&st, 0, sizeof(st));
st.level = 1;
for (i = 0; i < PTRS_PER_PGD; i++) {
if (!pgd_none(*start))
walk_level_2(m, &st, *start, i * LEVEL_1_MULT);
else
note_page(m, &st, __pgprot(0), 1);
start++;
}
}
static int ptdump_show(struct seq_file *m, void *v)
{
seq_puts(m, "Kernel pagetable dump\n");
walk_level_1(m);
return 0;
}
static int ptdump_open(struct inode *inode, struct file *filp)
{
return single_open(filp, ptdump_show, NULL);
}
static const struct file_operations ptdump_fops = {
.open = ptdump_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
int pt_dump_init(void)
{
struct dentry *pe;
pe = debugfs_create_file("kernel_page_tables", 0600, NULL, NULL,
&ptdump_fops);
if (!pe)
return -ENOMEM;
return 0;
}
__initcall(pt_dump_init);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");
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