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linux/arch/powerpc/mm/dump_linuxpagetables.c

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/*
* 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/hugetlb.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>
#ifdef CONFIG_PPC32
#define KERN_VIRT_START 0
#endif
/*
* 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 long start_pa;
unsigned long last_pa;
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" },
#ifdef CONFIG_PPC64
{ 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" },
#else
{ 0, "Early I/O remap start" },
{ 0, "Early I/O remap end" },
#ifdef CONFIG_NOT_COHERENT_CACHE
{ 0, "Consistent mem start" },
{ 0, "Consistent mem end" },
#endif
#ifdef CONFIG_HIGHMEM
{ 0, "Highmem PTEs start" },
{ 0, "Highmem PTEs end" },
#endif
{ 0, "Fixmap start" },
{ 0, "Fixmap end" },
#endif
{ -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[] = {
{
.mask = _PAGE_USER | _PAGE_PRIVILEGED,
.val = _PAGE_USER,
.set = "user",
.clear = " ",
}, {
.mask = _PAGE_RW | _PAGE_RO | _PAGE_NA,
.val = _PAGE_RW,
.set = "rw",
}, {
.mask = _PAGE_RW | _PAGE_RO | _PAGE_NA,
.val = _PAGE_RO,
.set = "ro",
}, {
#if _PAGE_NA != 0
.mask = _PAGE_RW | _PAGE_RO | _PAGE_NA,
.val = _PAGE_RO,
.set = "na",
}, {
#endif
.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_BOOK3S_64
.mask = H_PAGE_HASHPTE,
.val = H_PAGE_HASHPTE,
#else
.mask = _PAGE_HASHPTE,
.val = _PAGE_HASHPTE,
#endif
.set = "hpte",
.clear = " ",
}, {
#ifndef CONFIG_PPC_BOOK3S_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_BOOK3S_64
.mask = _PAGE_WRITETHRU,
.val = _PAGE_WRITETHRU,
.set = "write through",
.clear = " ",
}, {
#endif
#ifndef CONFIG_PPC_BOOK3S_64
.mask = _PAGE_NO_CACHE,
.val = _PAGE_NO_CACHE,
.set = "no cache",
.clear = " ",
}, {
#else
.mask = _PAGE_NON_IDEMPOTENT,
.val = _PAGE_NON_IDEMPOTENT,
.set = "non-idempotent",
.clear = " ",
}, {
.mask = _PAGE_TOLERANT,
.val = _PAGE_TOLERANT,
.set = "tolerant",
.clear = " ",
}, {
#endif
#ifdef CONFIG_PPC_BOOK3S_64
.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",
}, {
#else /* CONFIG_PPC_64K_PAGES */
.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",
}, {
#endif /* CONFIG_PPC_64K_PAGES */
#endif
.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;
#ifdef CONFIG_PPC64
seq_printf(st->seq, "0x%016lx-0x%016lx ", st->start_address, addr-1);
seq_printf(st->seq, "0x%016lx ", st->start_pa);
#else
seq_printf(st->seq, "0x%08lx-0x%08lx ", st->start_address, addr - 1);
seq_printf(st->seq, "0x%08lx ", st->start_pa);
#endif
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;
u64 pa = val & PTE_RPN_MASK;
/* At first no level is set */
if (!st->level) {
st->level = level;
st->current_flags = flag;
st->start_address = addr;
st->start_pa = pa;
st->last_pa = pa;
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.
* - the pa of this page is not adjacent to the last inspected page
*/
} else if (flag != st->current_flags || level != st->level ||
addr >= st->marker[1].start_address ||
pa != st->last_pa + PAGE_SIZE) {
/* 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_putc(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->start_pa = pa;
st->last_pa = pa;
st->current_flags = flag;
st->level = level;
} else {
st->last_pa = pa;
}
}
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_huge(*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_huge(*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_huge(*pgd))
/* pgd exists */
walk_pud(st, pgd, addr);
else
note_page(st, addr, 1, pgd_val(*pgd));
}
}
static void populate_markers(void)
{
int i = 0;
address_markers[i++].start_address = PAGE_OFFSET;
address_markers[i++].start_address = VMALLOC_START;
address_markers[i++].start_address = VMALLOC_END;
#ifdef CONFIG_PPC64
address_markers[i++].start_address = ISA_IO_BASE;
address_markers[i++].start_address = ISA_IO_END;
address_markers[i++].start_address = PHB_IO_BASE;
address_markers[i++].start_address = PHB_IO_END;
address_markers[i++].start_address = IOREMAP_BASE;
address_markers[i++].start_address = IOREMAP_END;
#ifdef CONFIG_PPC_BOOK3S_64
address_markers[i++].start_address = H_VMEMMAP_BASE;
#else
address_markers[i++].start_address = VMEMMAP_BASE;
#endif
#else /* !CONFIG_PPC64 */
address_markers[i++].start_address = ioremap_bot;
address_markers[i++].start_address = IOREMAP_TOP;
#ifdef CONFIG_NOT_COHERENT_CACHE
address_markers[i++].start_address = IOREMAP_TOP;
address_markers[i++].start_address = IOREMAP_TOP +
CONFIG_CONSISTENT_SIZE;
#endif
#ifdef CONFIG_HIGHMEM
address_markers[i++].start_address = PKMAP_BASE;
address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP);
#endif
address_markers[i++].start_address = FIXADDR_START;
address_markers[i++].start_address = FIXADDR_TOP;
#endif /* CONFIG_PPC64 */
}
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_page_tables", 0400, NULL,
NULL, &ptdump_fops);
return debugfs_file ? 0 : -ENOMEM;
}
device_initcall(ptdump_init);
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