forked from luck/tmp_suning_uos_patched
x86: add code to dump the (kernel) page tables for visual inspection by kernel developers
This patch adds code to the kernel to have an (optional) /proc/kernel_page_tables debug file that basically dumps the kernel pagetables; this allows us kernel developers to verify that nothing fishy is going on and that the various mappings are set up correctly. This was quite useful in finding various change_page_attr() bugs, and is very likely to be useful in the future as well. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Cc: mingo@elte.hu Cc: tglx@tglx.de Cc: hpa@zytor.com Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Arjan van de Ven
Ingo Molnar
parent
2596e0fae0
commit
926e5392ba
|
|
@ -54,6 +54,18 @@ config DEBUG_PER_CPU_MAPS
|
|||
|
||||
Say N if unsure.
|
||||
|
||||
config X86_PTDUMP
|
||||
bool "Export kernel pagetable layout to userspace via debugfs"
|
||||
depends on X86_64
|
||||
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 DEBUG_RODATA
|
||||
bool "Write protect kernel read-only data structures"
|
||||
default y
|
||||
|
|
|
|||
|
|
@ -12,4 +12,5 @@ else
|
|||
obj-$(CONFIG_NUMA) += numa_64.o
|
||||
obj-$(CONFIG_K8_NUMA) += k8topology_64.o
|
||||
obj-$(CONFIG_ACPI_NUMA) += srat_64.o
|
||||
obj-$(CONFIG_X86_PTDUMP) += dump_pagetables.o
|
||||
endif
|
||||
|
|
|
|||
301
arch/x86/mm/dump_pagetables.c
Normal file
301
arch/x86/mm/dump_pagetables.c
Normal file
|
|
@ -0,0 +1,301 @@
|
|||
/*
|
||||
* 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");
|
||||
Loading…
Reference in New Issue
Block a user