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// SPDX-License-Identifier: GPL-2.0
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/kasan.h>
#include <asm/sections.h>
#include <asm/pgtable.h>
static unsigned long max_addr;
struct addr_marker {
unsigned long start_address;
const char *name;
};
enum address_markers_idx {
IDENTITY_NR = 0,
KERNEL_START_NR,
KERNEL_END_NR,
#ifdef CONFIG_KASAN
KASAN_SHADOW_START_NR,
KASAN_SHADOW_END_NR,
#endif
VMEMMAP_NR,
VMALLOC_NR,
MODULES_NR,
};
static struct addr_marker address_markers[] = {
[IDENTITY_NR] = {0, "Identity Mapping"},
[KERNEL_START_NR] = {(unsigned long)_stext, "Kernel Image Start"},
[KERNEL_END_NR] = {(unsigned long)_end, "Kernel Image End"},
#ifdef CONFIG_KASAN
[KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"},
[KASAN_SHADOW_END_NR] = {KASAN_SHADOW_END, "Kasan Shadow End"},
#endif
[VMEMMAP_NR] = {0, "vmemmap Area"},
[VMALLOC_NR] = {0, "vmalloc Area"},
[MODULES_NR] = {0, "Modules Area"},
{ -1, NULL }
};
struct pg_state {
int level;
unsigned int current_prot;
unsigned long start_address;
unsigned long current_address;
const struct addr_marker *marker;
};
static void print_prot(struct seq_file *m, unsigned int pr, int level)
{
static const char * const level_name[] =
{ "ASCE", "PGD", "PUD", "PMD", "PTE" };
seq_printf(m, "%s ", level_name[level]);
if (pr & _PAGE_INVALID) {
seq_printf(m, "I\n");
return;
}
seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
}
static void note_page(struct seq_file *m, struct pg_state *st,
unsigned int new_prot, int level)
{
static const char units[] = "KMGTPE";
int width = sizeof(unsigned long) * 2;
const char *unit = units;
unsigned int prot, cur;
unsigned long delta;
/*
* 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 = new_prot;
cur = st->current_prot;
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) {
/* Print the actual finished series */
seq_printf(m, "0x%0*lx-0x%0*lx",
width, st->start_address,
width, st->current_address);
delta = (st->current_address - st->start_address) >> 10;
while (!(delta & 0x3ff) && unit[1]) {
delta >>= 10;
unit++;
}
seq_printf(m, "%9lu%c ", delta, *unit);
print_prot(m, st->current_prot, st->level);
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;
}
}
/*
* The actual page table walker functions. In order to keep the
* implementation of print_prot() short, we only check and pass
* _PAGE_INVALID and _PAGE_PROTECT flags to note_page() if a region,
* segment or page table entry is invalid or read-only.
* After all it's just a hint that the current level being walked
* contains an invalid or read-only entry.
*/
static void walk_pte_level(struct seq_file *m, struct pg_state *st,
pmd_t *pmd, unsigned long addr)
{
unsigned int prot;
pte_t *pte;
int i;
for (i = 0; i < PTRS_PER_PTE && addr < max_addr; i++) {
st->current_address = addr;
pte = pte_offset_kernel(pmd, addr);
prot = pte_val(*pte) &
(_PAGE_PROTECT | _PAGE_INVALID | _PAGE_NOEXEC);
note_page(m, st, prot, 4);
addr += PAGE_SIZE;
}
}
static void walk_pmd_level(struct seq_file *m, struct pg_state *st,
pud_t *pud, unsigned long addr)
{
unsigned int prot;
pmd_t *pmd;
int i;
for (i = 0; i < PTRS_PER_PMD && addr < max_addr; i++) {
st->current_address = addr;
pmd = pmd_offset(pud, addr);
if (!pmd_none(*pmd)) {
if (pmd_large(*pmd)) {
prot = pmd_val(*pmd) &
(_SEGMENT_ENTRY_PROTECT |
_SEGMENT_ENTRY_NOEXEC);
note_page(m, st, prot, 3);
} else
walk_pte_level(m, st, pmd, addr);
} else
note_page(m, st, _PAGE_INVALID, 3);
addr += PMD_SIZE;
}
}
static void walk_pud_level(struct seq_file *m, struct pg_state *st,
p4d_t *p4d, unsigned long addr)
{
unsigned int prot;
pud_t *pud;
int i;
for (i = 0; i < PTRS_PER_PUD && addr < max_addr; i++) {
st->current_address = addr;
pud = pud_offset(p4d, addr);
if (!pud_none(*pud))
if (pud_large(*pud)) {
prot = pud_val(*pud) &
(_REGION_ENTRY_PROTECT |
_REGION_ENTRY_NOEXEC);
note_page(m, st, prot, 2);
} else
walk_pmd_level(m, st, pud, addr);
else
note_page(m, st, _PAGE_INVALID, 2);
addr += PUD_SIZE;
}
}
static void walk_p4d_level(struct seq_file *m, struct pg_state *st,
pgd_t *pgd, unsigned long addr)
{
p4d_t *p4d;
int i;
for (i = 0; i < PTRS_PER_P4D && addr < max_addr; i++) {
st->current_address = addr;
p4d = p4d_offset(pgd, addr);
if (!p4d_none(*p4d))
walk_pud_level(m, st, p4d, addr);
else
note_page(m, st, _PAGE_INVALID, 2);
addr += P4D_SIZE;
}
}
static void walk_pgd_level(struct seq_file *m)
{
unsigned long addr = 0;
struct pg_state st;
pgd_t *pgd;
int i;
memset(&st, 0, sizeof(st));
for (i = 0; i < PTRS_PER_PGD && addr < max_addr; i++) {
st.current_address = addr;
pgd = pgd_offset_k(addr);
if (!pgd_none(*pgd))
walk_p4d_level(m, &st, pgd, addr);
else
note_page(m, &st, _PAGE_INVALID, 1);
addr += PGDIR_SIZE;
cond_resched();
}
/* Flush out the last page */
st.current_address = max_addr;
note_page(m, &st, 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)
{
/*
* Figure out the maximum virtual address being accessible with the
* kernel ASCE. We need this to keep the page table walker functions
* from accessing non-existent entries.
*/
max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
max_addr = 1UL << (max_addr * 11 + 31);
address_markers[MODULES_NR].start_address = MODULES_VADDR;
address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
address_markers[VMALLOC_NR].start_address = VMALLOC_START;
debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
return 0;
}
device_initcall(pt_dump_init);
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