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alistair23-linux/arch/x86/mm/dump_pagetables.c
Linus Torvalds a023748d53 Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 
Pull x86 mm tree changes from Ingo Molnar:
 "The biggest change is full PAT support from Jürgen Gross:

     The x86 architecture offers via the PAT (Page Attribute Table) a
     way to specify different caching modes in page table entries.  The
     PAT MSR contains 8 entries each specifying one of 6 possible cache
     modes.  A pte references one of those entries via 3 bits:
     _PAGE_PAT, _PAGE_PWT and _PAGE_PCD.

     The Linux kernel currently supports only 4 different cache modes.
     The PAT MSR is set up in a way that the setting of _PAGE_PAT in a
     pte doesn't matter: the top 4 entries in the PAT MSR are the same
     as the 4 lower entries.

     This results in the kernel not supporting e.g. write-through mode.
     Especially this cache mode would speed up drivers of video cards
     which now have to use uncached accesses.

     OTOH some old processors (Pentium) don't support PAT correctly and
     the Xen hypervisor has been using a different PAT MSR configuration
     for some time now and can't change that as this setting is part of
     the ABI.

     This patch set abstracts the cache mode from the pte and introduces
     tables to translate between cache mode and pte bits (the default
     cache mode "write back" is hard-wired to PAT entry 0).  The tables
     are statically initialized with values being compatible to old
     processors and current usage.  As soon as the PAT MSR is changed
     (or - in case of Xen - is read at boot time) the tables are changed
     accordingly.  Requests of mappings with special cache modes are
     always possible now, in case they are not supported there will be a
     fallback to a compatible but slower mode.

     Summing it up, this patch set adds the following features:

      - capability to support WT and WP cache modes on processors with
        full PAT support

      - processors with no or uncorrect PAT support are still working as
        today, even if WT or WP cache mode are selected by drivers for
        some pages

      - reduction of Xen special handling regarding cache mode

  Another change is a boot speedup on ridiculously large RAM systems,
  plus other smaller fixes"

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
  x86: mm: Move PAT only functions to mm/pat.c
  xen: Support Xen pv-domains using PAT
  x86: Enable PAT to use cache mode translation tables
  x86: Respect PAT bit when copying pte values between large and normal pages
  x86: Support PAT bit in pagetable dump for lower levels
  x86: Clean up pgtable_types.h
  x86: Use new cache mode type in memtype related functions
  x86: Use new cache mode type in mm/ioremap.c
  x86: Use new cache mode type in setting page attributes
  x86: Remove looking for setting of _PAGE_PAT_LARGE in pageattr.c
  x86: Use new cache mode type in track_pfn_remap() and track_pfn_insert()
  x86: Use new cache mode type in mm/iomap_32.c
  x86: Use new cache mode type in asm/pgtable.h
  x86: Use new cache mode type in arch/x86/mm/init_64.c
  x86: Use new cache mode type in arch/x86/pci
  x86: Use new cache mode type in drivers/video/fbdev/vermilion
  x86: Use new cache mode type in drivers/video/fbdev/gbefb.c
  x86: Use new cache mode type in include/asm/fb.h
  x86: Make page cache mode a real type
  x86: mm: Use 2GB memory block size on large-memory x86-64 systems
  ...
2014-12-10 13:59:34 -08:00

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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/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;
unsigned long lines;
bool to_dmesg;
};
struct addr_marker {
unsigned long start_address;
const char *name;
unsigned long max_lines;
};
/* indices for address_markers; keep sync'd w/ address_markers below */
enum address_markers_idx {
USER_SPACE_NR = 0,
#ifdef CONFIG_X86_64
KERNEL_SPACE_NR,
LOW_KERNEL_NR,
VMALLOC_START_NR,
VMEMMAP_START_NR,
# ifdef CONFIG_X86_ESPFIX64
ESPFIX_START_NR,
# endif
HIGH_KERNEL_NR,
MODULES_VADDR_NR,
MODULES_END_NR,
#else
KERNEL_SPACE_NR,
VMALLOC_START_NR,
VMALLOC_END_NR,
# ifdef CONFIG_HIGHMEM
PKMAP_BASE_NR,
# endif
FIXADDR_START_NR,
#endif
};
/* 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" },
# ifdef CONFIG_X86_ESPFIX64
{ ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
# endif
# ifdef CONFIG_EFI
{ EFI_VA_END, "EFI Runtime Services" },
# endif
{ __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)
#define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
({ \
if (to_dmesg) \
printk(KERN_INFO fmt, ##args); \
else \
if (m) \
seq_printf(m, fmt, ##args); \
})
#define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
({ \
if (to_dmesg) \
printk(KERN_CONT fmt, ##args); \
else \
if (m) \
seq_printf(m, fmt, ##args); \
})
/*
* 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, bool dmsg)
{
pgprotval_t pr = pgprot_val(prot);
static const char * const level_name[] =
{ "cr3", "pgd", "pud", "pmd", "pte" };
if (!pgprot_val(prot)) {
/* Not present */
pt_dump_cont_printf(m, dmsg, " ");
} else {
if (pr & _PAGE_USER)
pt_dump_cont_printf(m, dmsg, "USR ");
else
pt_dump_cont_printf(m, dmsg, " ");
if (pr & _PAGE_RW)
pt_dump_cont_printf(m, dmsg, "RW ");
else
pt_dump_cont_printf(m, dmsg, "ro ");
if (pr & _PAGE_PWT)
pt_dump_cont_printf(m, dmsg, "PWT ");
else
pt_dump_cont_printf(m, dmsg, " ");
if (pr & _PAGE_PCD)
pt_dump_cont_printf(m, dmsg, "PCD ");
else
pt_dump_cont_printf(m, dmsg, " ");
/* Bit 7 has a different meaning on level 3 vs 4 */
if (level <= 3 && pr & _PAGE_PSE)
pt_dump_cont_printf(m, dmsg, "PSE ");
else
pt_dump_cont_printf(m, dmsg, " ");
if ((level == 4 && pr & _PAGE_PAT) ||
((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE))
pt_dump_cont_printf(m, dmsg, "pat ");
else
pt_dump_cont_printf(m, dmsg, " ");
if (pr & _PAGE_GLOBAL)
pt_dump_cont_printf(m, dmsg, "GLB ");
else
pt_dump_cont_printf(m, dmsg, " ");
if (pr & _PAGE_NX)
pt_dump_cont_printf(m, dmsg, "NX ");
else
pt_dump_cont_printf(m, dmsg, "x ");
}
pt_dump_cont_printf(m, dmsg, "%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[] = "BKMGTPE";
/*
* 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_FLAGS_MASK;
cur = pgprot_val(st->current_prot) & PTE_FLAGS_MASK;
if (!st->level) {
/* First entry */
st->current_prot = new_prot;
st->level = level;
st->marker = address_markers;
st->lines = 0;
pt_dump_seq_printf(m, st->to_dmesg, "---[ %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;
int width = sizeof(unsigned long) * 2;
/*
* Now print the actual finished series
*/
if (!st->marker->max_lines ||
st->lines < st->marker->max_lines) {
pt_dump_seq_printf(m, st->to_dmesg,
"0x%0*lx-0x%0*lx ",
width, st->start_address,
width, st->current_address);
delta = st->current_address - st->start_address;
while (!(delta & 1023) && unit[1]) {
delta >>= 10;
unit++;
}
pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
delta, *unit);
printk_prot(m, st->current_prot, st->level,
st->to_dmesg);
}
st->lines++;
/*
* 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) {
if (st->marker->max_lines &&
st->lines > st->marker->max_lines) {
unsigned long nskip =
st->lines - st->marker->max_lines;
pt_dump_seq_printf(m, st->to_dmesg,
"... %lu entr%s skipped ... \n",
nskip,
nskip == 1 ? "y" : "ies");
}
st->marker++;
st->lines = 0;
pt_dump_seq_printf(m, st->to_dmesg, "---[ %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
void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
{
#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 = {};
if (pgd) {
start = pgd;
st.to_dmesg = true;
}
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)
{
ptdump_walk_pgd_level(m, NULL);
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[VMALLOC_START_NR].start_address = VMALLOC_START;
address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
# ifdef CONFIG_HIGHMEM
address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
# endif
address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
#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");
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