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// SPDX-License-Identifier: GPL-2.0
#include <linux/set_memory.h>
#include <linux/ptdump.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/mm.h>
#include <linux/kasan.h>
#include <asm/ptdump.h>
#include <asm/kasan.h>
#include <asm/sections.h>
static unsigned long max_addr;
struct addr_marker {
unsigned long start_address;
const char *name;
};
enum address_markers_idx {
IDENTITY_BEFORE_NR = 0,
IDENTITY_BEFORE_END_NR,
KERNEL_START_NR,
KERNEL_END_NR,
IDENTITY_AFTER_NR,
IDENTITY_AFTER_END_NR,
#ifdef CONFIG_KASAN
KASAN_SHADOW_START_NR,
KASAN_SHADOW_END_NR,
#endif
VMEMMAP_NR,
VMEMMAP_END_NR,
VMALLOC_NR,
VMALLOC_END_NR,
MODULES_NR,
MODULES_END_NR,
};
static struct addr_marker address_markers[] = {
[IDENTITY_BEFORE_NR] = {0, "Identity Mapping Start"},
[IDENTITY_BEFORE_END_NR] = {(unsigned long)_stext, "Identity Mapping End"},
[KERNEL_START_NR] = {(unsigned long)_stext, "Kernel Image Start"},
[KERNEL_END_NR] = {(unsigned long)_end, "Kernel Image End"},
[IDENTITY_AFTER_NR] = {(unsigned long)_end, "Identity Mapping Start"},
[IDENTITY_AFTER_END_NR] = {0, "Identity Mapping 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 Start"},
[VMEMMAP_END_NR] = {0, "vmemmap Area End"},
[VMALLOC_NR] = {0, "vmalloc Area Start"},
[VMALLOC_END_NR] = {0, "vmalloc Area End"},
[MODULES_NR] = {0, "Modules Area Start"},
[MODULES_END_NR] = {0, "Modules Area End"},
{ -1, NULL }
};
struct pg_state {
struct ptdump_state ptdump;
struct seq_file *seq;
int level;
unsigned int current_prot;
bool check_wx;
unsigned long wx_pages;
unsigned long start_address;
const struct addr_marker *marker;
};
#define pt_dump_seq_printf(m, fmt, args...) \
({ \
struct seq_file *__m = (m); \
\
if (__m) \
seq_printf(__m, fmt, ##args); \
})
#define pt_dump_seq_puts(m, fmt) \
({ \
struct seq_file *__m = (m); \
\
if (__m) \
seq_printf(__m, fmt); \
})
static void print_prot(struct seq_file *m, unsigned int pr, int level)
{
static const char * const level_name[] =
{ "ASCE", "PGD", "PUD", "PMD", "PTE" };
pt_dump_seq_printf(m, "%s ", level_name[level]);
if (pr & _PAGE_INVALID) {
pt_dump_seq_printf(m, "I\n");
return;
}
pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
}
static void note_prot_wx(struct pg_state *st, unsigned long addr)
{
#ifdef CONFIG_DEBUG_WX
if (!st->check_wx)
return;
if (st->current_prot & _PAGE_INVALID)
return;
if (st->current_prot & _PAGE_PROTECT)
return;
if (st->current_prot & _PAGE_NOEXEC)
return;
/* The first lowcore page is currently still W+X. */
if (addr == PAGE_SIZE)
return;
WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n",
(void *)st->start_address);
st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
#endif /* CONFIG_DEBUG_WX */
}
static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
{
int width = sizeof(unsigned long) * 2;
static const char units[] = "KMGTPE";
const char *unit = units;
unsigned long delta;
struct pg_state *st;
struct seq_file *m;
unsigned int prot;
st = container_of(pt_st, struct pg_state, ptdump);
m = st->seq;
prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC);
if (level == 4 && (val & _PAGE_INVALID))
prot = _PAGE_INVALID;
/* For pmd_none() & friends val gets passed as zero. */
if (level != 4 && !val)
prot = _PAGE_INVALID;
/* Final flush from generic code. */
if (level == -1)
addr = max_addr;
if (st->level == -1) {
pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
st->start_address = addr;
st->current_prot = prot;
st->level = level;
} else if (prot != st->current_prot || level != st->level ||
addr >= st->marker[1].start_address) {
note_prot_wx(st, addr);
pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
width, st->start_address,
width, addr);
delta = (addr - st->start_address) >> 10;
while (!(delta & 0x3ff) && unit[1]) {
delta >>= 10;
unit++;
}
pt_dump_seq_printf(m, "%9lu%c ", delta, *unit);
print_prot(m, st->current_prot, st->level);
while (addr >= st->marker[1].start_address) {
st->marker++;
pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
}
st->start_address = addr;
st->current_prot = prot;
st->level = level;
}
}
#ifdef CONFIG_DEBUG_WX
void ptdump_check_wx(void)
{
struct pg_state st = {
.ptdump = {
.note_page = note_page,
.range = (struct ptdump_range[]) {
{.start = 0, .end = max_addr},
{.start = 0, .end = 0},
}
},
.seq = NULL,
.level = -1,
.current_prot = 0,
.check_wx = true,
.wx_pages = 0,
.start_address = 0,
.marker = (struct addr_marker[]) {
{ .start_address = 0, .name = NULL},
{ .start_address = -1, .name = NULL},
},
};
if (!MACHINE_HAS_NX)
return;
ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
if (st.wx_pages)
pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
else
pr_info("Checked W+X mappings: passed, no unexpected W+X pages found\n");
}
#endif /* CONFIG_DEBUG_WX */
#ifdef CONFIG_PTDUMP_DEBUGFS
static int ptdump_show(struct seq_file *m, void *v)
{
struct pg_state st = {
.ptdump = {
.note_page = note_page,
.range = (struct ptdump_range[]) {
{.start = 0, .end = max_addr},
{.start = 0, .end = 0},
}
},
.seq = m,
.level = -1,
.current_prot = 0,
.check_wx = false,
.wx_pages = 0,
.start_address = 0,
.marker = address_markers,
};
get_online_mems();
mutex_lock(&cpa_mutex);
ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
mutex_unlock(&cpa_mutex);
put_online_mems();
return 0;
}
DEFINE_SHOW_ATTRIBUTE(ptdump);
#endif /* CONFIG_PTDUMP_DEBUGFS */
/*
* Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple
* insertion sort to preserve the original order of markers with the same
* start address.
*/
static void sort_address_markers(void)
{
struct addr_marker tmp;
int i, j;
for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) {
tmp = address_markers[i];
for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--)
address_markers[j + 1] = address_markers[j];
address_markers[j + 1] = tmp;
}
}
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[IDENTITY_AFTER_END_NR].start_address = ident_map_size;
address_markers[MODULES_NR].start_address = MODULES_VADDR;
address_markers[MODULES_END_NR].start_address = MODULES_END;
address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size;
address_markers[VMALLOC_NR].start_address = VMALLOC_START;
address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
sort_address_markers();
#ifdef CONFIG_PTDUMP_DEBUGFS
debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
#endif /* CONFIG_PTDUMP_DEBUGFS */
return 0;
}
device_initcall(pt_dump_init);
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