jenna
/
kernel_samsung_sm7125
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

powerpc/mm: Dump linux pagetables

Browse Source 
Useful to be able to dump the kernels page tables to check permissions
and memory types - derived from arm64's implementation.

Add a debugfs file to check the page tables. To use this the PPC_PTDUMP
config option must be selected.

Signed-off-by: Rashmica Gupta <rashmicy@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
tirimbino
Rashmica Gupta 9 years ago committed by Michael Ellerman
parent 8f272a5dd6
commit 8eb07b1870
3 changed files with 453 additions and 0 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 12
      arch/powerpc/Kconfig.debug
  2. 1
      arch/powerpc/mm/Makefile
  3. 440
      arch/powerpc/mm/dump_linuxpagetables.c

12
arch/powerpc/Kconfig.debug
Unescape View File

@ -354,4 +354,16 @@ config FAIL_IOMMU
If you are unsure, say N. If you are unsure, say N.
config PPC_PTDUMP
bool "Export kernel pagetable layout to userspace via debugfs"
depends on DEBUG_KERNEL
select DEBUG_FS
help
This option exports the state of the kernel pagetables to a
debugfs file. This is only useful for kernel developers who are
working in architecture specific areas of the kernel - probably
not a good idea to enable this feature in a production kernel.
If you are unsure, say N.
endmenu endmenu

1
arch/powerpc/mm/Makefile
Unescape View File

@ -42,3 +42,4 @@ obj-$(CONFIG_NOT_COHERENT_CACHE) += dma-noncoherent.o
obj-$(CONFIG_HIGHMEM) += highmem.o obj-$(CONFIG_HIGHMEM) += highmem.o
obj-$(CONFIG_PPC_COPRO_BASE) += copro_fault.o obj-$(CONFIG_PPC_COPRO_BASE) += copro_fault.o
obj-$(CONFIG_SPAPR_TCE_IOMMU) += mmu_context_iommu.o obj-$(CONFIG_SPAPR_TCE_IOMMU) += mmu_context_iommu.o
obj-$(CONFIG_PPC_PTDUMP) += dump_linuxpagetables.o

440
arch/powerpc/mm/dump_linuxpagetables.c
Unescape View File

@ -0,0 +1,440 @@
/*
* Copyright 2016, Rashmica Gupta, IBM Corp.
*
* This traverses the kernel pagetables and dumps the
* information about the used sections of memory to
* /sys/kernel/debug/kernel_pagetables.
*
* Derived from the arm64 implementation:
* Copyright (c) 2014, The Linux Foundation, Laura Abbott.
* (C) Copyright 2008 Intel Corporation, Arjan van de Ven.
*
* 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/io.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <asm/fixmap.h>
#include <asm/pgtable.h>
#include <linux/const.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
/*
* To visualise what is happening,
*
* - PTRS_PER_P** = how many entries there are in the corresponding P**
* - P**_SHIFT = how many bits of the address we use to index into the
* corresponding P**
* - P**_SIZE is how much memory we can access through the table - not the
* size of the table itself.
* P**={PGD, PUD, PMD, PTE}
*
*
* Each entry of the PGD points to a PUD. Each entry of a PUD points to a
* PMD. Each entry of a PMD points to a PTE. And every PTE entry points to
* a page.
*
* In the case where there are only 3 levels, the PUD is folded into the
* PGD: every PUD has only one entry which points to the PMD.
*
* The page dumper groups page table entries of the same type into a single
* description. It uses pg_state to track the range information while
* iterating over the PTE entries. When the continuity is broken it then
* dumps out a description of the range - ie PTEs that are virtually contiguous
* with the same PTE flags are chunked together. This is to make it clear how
* different areas of the kernel virtual memory are used.
*
*/
struct pg_state {
struct seq_file *seq;
const struct addr_marker *marker;
unsigned long start_address;
unsigned int level;
u64 current_flags;
};
struct addr_marker {
unsigned long start_address;
const char *name;
};
static struct addr_marker address_markers[] = {
{ 0, "Start of kernel VM" },
{ 0, "vmalloc() Area" },
{ 0, "vmalloc() End" },
{ 0, "isa I/O start" },
{ 0, "isa I/O end" },
{ 0, "phb I/O start" },
{ 0, "phb I/O end" },
{ 0, "I/O remap start" },
{ 0, "I/O remap end" },
{ 0, "vmemmap start" },
{ -1, NULL },
};
struct flag_info {
u64 mask;
u64 val;
const char *set;
const char *clear;
bool is_val;
int shift;
};
static const struct flag_info flag_array[] = {
{
#ifdef CONFIG_PPC_STD_MMU_64
.mask = _PAGE_PRIVILEGED,
.val = 0,
#else
.mask = _PAGE_USER,
.val = _PAGE_USER,
#endif
.set = "user",
.clear = " ",
}, {
.mask = _PAGE_RW,
.val = _PAGE_RW,
.set = "rw",
.clear = "ro",
}, {
.mask = _PAGE_EXEC,
.val = _PAGE_EXEC,
.set = " X ",
.clear = " ",
}, {
.mask = _PAGE_PTE,
.val = _PAGE_PTE,
.set = "pte",
.clear = " ",
}, {
.mask = _PAGE_PRESENT,
.val = _PAGE_PRESENT,
.set = "present",
.clear = " ",
}, {
#ifdef CONFIG_PPC_STD_MMU_64
.mask = H_PAGE_HASHPTE,
.val = H_PAGE_HASHPTE,
#else
.mask = _PAGE_HASHPTE,
.val = _PAGE_HASHPTE,
#endif
.set = "hpte",
.clear = " ",
}, {
#ifndef CONFIG_PPC_STD_MMU_64
.mask = _PAGE_GUARDED,
.val = _PAGE_GUARDED,
.set = "guarded",
.clear = " ",
}, {
#endif
.mask = _PAGE_DIRTY,
.val = _PAGE_DIRTY,
.set = "dirty",
.clear = " ",
}, {
.mask = _PAGE_ACCESSED,
.val = _PAGE_ACCESSED,
.set = "accessed",
.clear = " ",
}, {
#ifndef CONFIG_PPC_STD_MMU_64
.mask = _PAGE_WRITETHRU,
.val = _PAGE_WRITETHRU,
.set = "write through",
.clear = " ",
}, {
#endif
.mask = _PAGE_NO_CACHE,
.val = _PAGE_NO_CACHE,
.set = "no cache",
.clear = " ",
}, {
.mask = H_PAGE_BUSY,
.val = H_PAGE_BUSY,
.set = "busy",
}, {
#ifdef CONFIG_PPC_64K_PAGES
.mask = H_PAGE_COMBO,
.val = H_PAGE_COMBO,
.set = "combo",
}, {
.mask = H_PAGE_4K_PFN,
.val = H_PAGE_4K_PFN,
.set = "4K_pfn",
}, {
#endif
.mask = H_PAGE_F_GIX,
.val = H_PAGE_F_GIX,
.set = "f_gix",
.is_val = true,
.shift = H_PAGE_F_GIX_SHIFT,
}, {
.mask = H_PAGE_F_SECOND,
.val = H_PAGE_F_SECOND,
.set = "f_second",
}, {
.mask = _PAGE_SPECIAL,
.val = _PAGE_SPECIAL,
.set = "special",
}
};
struct pgtable_level {
const struct flag_info *flag;
size_t num;
u64 mask;
};
static struct pgtable_level pg_level[] = {
{
}, { /* pgd */
.flag = flag_array,
.num = ARRAY_SIZE(flag_array),
}, { /* pud */
.flag = flag_array,
.num = ARRAY_SIZE(flag_array),
}, { /* pmd */
.flag = flag_array,
.num = ARRAY_SIZE(flag_array),
}, { /* pte */
.flag = flag_array,
.num = ARRAY_SIZE(flag_array),
},
};
static void dump_flag_info(struct pg_state *st, const struct flag_info
*flag, u64 pte, int num)
{
unsigned int i;
for (i = 0; i < num; i++, flag++) {
const char *s = NULL;
u64 val;
/* flag not defined so don't check it */
if (flag->mask == 0)
continue;
/* Some 'flags' are actually values */
if (flag->is_val) {
val = pte & flag->val;
if (flag->shift)
val = val >> flag->shift;
seq_printf(st->seq, " %s:%llx", flag->set, val);
} else {
if ((pte & flag->mask) == flag->val)
s = flag->set;
else
s = flag->clear;
if (s)
seq_printf(st->seq, " %s", s);
}
st->current_flags &= ~flag->mask;
}
if (st->current_flags != 0)
seq_printf(st->seq, " unknown flags:%llx", st->current_flags);
}
static void dump_addr(struct pg_state *st, unsigned long addr)
{
static const char units[] = "KMGTPE";
const char *unit = units;
unsigned long delta;
seq_printf(st->seq, "0x%016lx-0x%016lx ", st->start_address, addr-1);
delta = (addr - st->start_address) >> 10;
/* Work out what appropriate unit to use */
while (!(delta & 1023) && unit[1]) {
delta >>= 10;
unit++;
}
seq_printf(st->seq, "%9lu%c", delta, *unit);
}
static void note_page(struct pg_state *st, unsigned long addr,
unsigned int level, u64 val)
{
u64 flag = val & pg_level[level].mask;
/* At first no level is set */
if (!st->level) {
st->level = level;
st->current_flags = flag;
st->start_address = addr;
seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
/*
* Dump the section of virtual memory when:
* - the PTE flags from one entry to the next differs.
* - we change levels in the tree.
* - the address is in a different section of memory and is thus
* used for a different purpose, regardless of the flags.
*/
} else if (flag != st->current_flags || level != st->level ||
addr >= st->marker[1].start_address) {
/* Check the PTE flags */
if (st->current_flags) {
dump_addr(st, addr);
/* Dump all the flags */
if (pg_level[st->level].flag)
dump_flag_info(st, pg_level[st->level].flag,
st->current_flags,
pg_level[st->level].num);
seq_puts(st->seq, "\n");
}
/*
* Address indicates we have passed the end of the
* current section of virtual memory
*/
while (addr >= st->marker[1].start_address) {
st->marker++;
seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
}
st->start_address = addr;
st->current_flags = flag;
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 int 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 int i;
for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
addr = start + i * PMD_SIZE;
if (!pmd_none(*pmd))
/* pmd exists */
walk_pte(st, pmd, addr);
else
note_page(st, addr, 3, pmd_val(*pmd));
}
}
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 int i;
for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
addr = start + i * PUD_SIZE;
if (!pud_none(*pud))
/* pud exists */
walk_pmd(st, pud, addr);
else
note_page(st, addr, 2, pud_val(*pud));
}
}
static void walk_pagetables(struct pg_state *st)
{
pgd_t *pgd = pgd_offset_k(0UL);
unsigned int i;
unsigned long addr;
/*
* Traverse the linux pagetable structure and dump pages that are in
* the hash pagetable.
*/
for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
addr = KERN_VIRT_START + i * PGDIR_SIZE;
if (!pgd_none(*pgd))
/* pgd exists */
walk_pud(st, pgd, addr);
else
note_page(st, addr, 1, pgd_val(*pgd));
}
}
static void populate_markers(void)
{
address_markers[0].start_address = PAGE_OFFSET;
address_markers[1].start_address = VMALLOC_START;
address_markers[2].start_address = VMALLOC_END;
address_markers[3].start_address = ISA_IO_BASE;
address_markers[4].start_address = ISA_IO_END;
address_markers[5].start_address = PHB_IO_BASE;
address_markers[6].start_address = PHB_IO_END;
address_markers[7].start_address = IOREMAP_BASE;
address_markers[8].start_address = IOREMAP_END;
#ifdef CONFIG_PPC_STD_MMU_64
address_markers[9].start_address = H_VMEMMAP_BASE;
#else
address_markers[9].start_address = VMEMMAP_BASE;
#endif
}
static int ptdump_show(struct seq_file *m, void *v)
{
struct pg_state st = {
.seq = m,
.start_address = KERN_VIRT_START,
.marker = address_markers,
};
/* Traverse kernel page tables */
walk_pagetables(&st);
note_page(&st, 0, 0, 0);
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 void build_pgtable_complete_mask(void)
{
unsigned int i, j;
for (i = 0; i < ARRAY_SIZE(pg_level); i++)
if (pg_level[i].flag)
for (j = 0; j < pg_level[i].num; j++)
pg_level[i].mask |= pg_level[i].flag[j].mask;
}
static int ptdump_init(void)
{
struct dentry *debugfs_file;
populate_markers();
build_pgtable_complete_mask();
debugfs_file = debugfs_create_file("kernel_pagetables", 0400, NULL,
NULL, &ptdump_fops);
return debugfs_file ? 0 : -ENOMEM;
}
device_initcall(ptdump_init);
Write Preview
Loading…
Cancel
Save