/*
* 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/debugfs.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/seq_file.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;
const struct addr_marker *marker;
};
struct addr_marker {
unsigned long start_address;
const char *name;
};
/* Address space markers hints */
static struct addr_marker address_markers[] = {
{ 0, "User Space" },
#ifdef CONFIG_X86_64
{ 0x8000000000000000UL, "Kernel Space" },
{ PAGE_OFFSET, "Low Kernel Mapping" },
{ VMALLOC_START, "vmalloc() Area" },
{ VMEMMAP_START, "Vmemmap" },
{ __START_KERNEL_map, "High Kernel Mapping" },
{ MODULES_VADDR, "Modules" },
{ MODULES_END, "End Modules" },
#else
{ PAGE_OFFSET, "Kernel Mapping" },
{ 0/* VMALLOC_START */, "vmalloc() Area" },
{ 0/*VMALLOC_END*/, "vmalloc() End" },
# ifdef CONFIG_HIGHMEM
{ 0/*PKMAP_BASE*/, "Persisent kmap() Area" },
# endif
{ 0/*FIXADDR_START*/, "Fixmap Area" },
#endif
{ -1, NULL } /* End of list */
};
/* Multipliers for offsets within the PTEs */
#define PTE_LEVEL_MULT (PAGE_SIZE)
#define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
#define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
#define PGD_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_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)
{
pgprotval_t pr = pgprot_val(prot);
static const char * const level_name[] =
{ "cr3", "pgd", "pud", "pmd", "pte" };
if (!pgprot_val(prot)) {
/* Not present */
seq_printf(m, " ");
} else {
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 ");
}
seq_printf(m, "%s\n", level_name[level]);
}
/*
* On 64 bits, sign-extend the 48 bit address to 64 bit
*/
static unsigned long normalize_addr(unsigned long u)
{
#ifdef CONFIG_X86_64
return (signed long)(u << 16) >> 16;
#else
return u;
#endif
}
/*
* 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)
{
pgprotval_t prot, cur;
static const char units[] = "KMGTPE";
/*
* If we have a "break" in the series, we need to flush the state that
* we have now. "break" is either changing perms, levels or
* address space marker.
*/
prot = pgprot_val(new_prot) & ~(PTE_PFN_MASK);
cur = pgprot_val(st->current_prot) & ~(PTE_PFN_MASK);
if (!st->level) {
/* First entry */
st->current_prot = new_prot;
st->level = level;
st->marker = address_markers;
seq_printf(m, "---[ %s ]---\n", st->marker->name);
} else if (prot != cur || level != st->level ||
st->current_address >= st->marker[1].start_address) {
const char *unit = units;
unsigned long delta;
/*
* Now print the actual finished series
*/
seq_printf(m, "0x%p-0x%p ",
(void *)st->start_address,
(void *)st->current_address);
delta = (st->current_address - st->start_address) >> 10;
while (!(delta & 1023) && unit[1]) {
delta >>= 10;
unit++;
}
seq_printf(m, "%9lu%c ", delta, *unit);
printk_prot(m, st->current_prot, st->level);
/*
* We print markers for special areas of address space,
* such as the start of vmalloc space etc.
* This helps in the interpretation.
*/
if (st->current_address >= st->marker[1].start_address) {
st->marker++;
seq_printf(m, "---[ %s ]---\n", st->marker->name);
}
st->start_address = st->current_address;
st->current_prot = new_prot;
st->level = level;
}
}
static void walk_pte_level(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 = normalize_addr(P + i * PTE_LEVEL_MULT);
note_page(m, st, prot, 4);
start++;
}
}
#if PTRS_PER_PMD > 1
static void walk_pmd_level(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 = normalize_addr(P + i * PMD_LEVEL_MULT);
if (!pmd_none(*start)) {
pgprotval_t prot = pmd_val(*start) & PTE_FLAGS_MASK;
if (pmd_large(*start) || !pmd_present(*start))
note_page(m, st, __pgprot(prot), 3);
else
walk_pte_level(m, st, *start,
P + i * PMD_LEVEL_MULT);
} else
note_page(m, st, __pgprot(0), 3);
start++;
}
}
#else
#define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p)
#define pud_large(a) pmd_large(__pmd(pud_val(a)))
#define pud_none(a) pmd_none(__pmd(pud_val(a)))
#endif
#if PTRS_PER_PUD > 1
static void walk_pud_level(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++) {
st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
if (!pud_none(*start)) {
pgprotval_t prot = pud_val(*start) & PTE_FLAGS_MASK;
if (pud_large(*start) || !pud_present(*start))
note_page(m, st, __pgprot(prot), 2);
else
walk_pmd_level(m, st, *start,
P + i * PUD_LEVEL_MULT);
} else
note_page(m, st, __pgprot(0), 2);
start++;
}
}
#else
#define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(pgd_val(a)),p)
#define pgd_large(a) pud_large(__pud(pgd_val(a)))
#define pgd_none(a) pud_none(__pud(pgd_val(a)))
#endif
static void walk_pgd_level(struct seq_file *m)
{
#ifdef CONFIG_X86_64
pgd_t *start = (pgd_t *) &init_level4_pgt;
#else
pgd_t *start = swapper_pg_dir;
#endif
int i;
struct pg_state st;
memset(&st, 0, sizeof(st));
for (i = 0; i < PTRS_PER_PGD; i++) {
st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
if (!pgd_none(*start)) {
pgprotval_t prot = pgd_val(*start) & PTE_FLAGS_MASK;
if (pgd_large(*start) || !pgd_present(*start))
note_page(m, &st, __pgprot(prot), 1);
else
walk_pud_level(m, &st, *start,
i * PGD_LEVEL_MULT);
} else
note_page(m, &st, __pgprot(0), 1);
start++;
}
/* Flush out the last page */
st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
note_page(m, &st, __pgprot(0), 0);
}
static int ptdump_show(struct seq_file *m, void *v)
{
walk_pgd_level(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,
};
static int pt_dump_init(void)
{
struct dentry *pe;
#ifdef CONFIG_X86_32
/* Not a compile-time constant on x86-32 */
address_markers[2].start_address = VMALLOC_START;
address_markers[3].start_address = VMALLOC_END;
# ifdef CONFIG_HIGHMEM
address_markers[4].start_address = PKMAP_BASE;
address_markers[5].start_address = FIXADDR_START;
# else
address_markers[4].start_address = FIXADDR_START;
# endif
#endif
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");
