// 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/sort.h>
#include <linux/mm.h>
#include <linux/kfence.h>
#include <linux/kasan.h>
#include <asm/kasan.h>
#include <asm/abs_lowcore.h>
#include <asm/nospec-branch.h>
#include <asm/sections.h>
#include <asm/maccess.h>
static unsigned long max_addr;
struct addr_marker {
int is_start;
unsigned long start_address;
unsigned long size;
const char *name;
};
static struct addr_marker *markers;
static unsigned int markers_cnt;
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)
{
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 W+X if spectre mitigations are using
* trampolines or the BEAR enhancements facility is not installed,
* in which case we have two lpswe instructions in lowcore that need
* to be executable.
*/
if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)))
return;
WARN_ONCE(IS_ENABLED(CONFIG_DEBUG_WX),
"s390/mm: Found insecure W+X mapping at address %pS\n",
(void *)st->start_address);
st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
}
static void note_page_update_state(struct pg_state *st, unsigned long addr, unsigned int prot, int level)
{
struct seq_file *m = st->seq;
while (addr >= st->marker[1].start_address) {
st->marker++;
pt_dump_seq_printf(m, "---[ %s %s ]---\n", st->marker->name,
st->marker->is_start ? "Start" : "End");
}
st->start_address = addr;
st->current_prot = prot;
st->level = level;
}
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_puts(m, "---[ Kernel Virtual Address Space ]---\n");
note_page_update_state(st, addr, prot, 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);
note_page_update_state(st, addr, prot, level);
}
}
bool 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 true;
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);
return false;
} else {
pr_info("Checked W+X mappings: passed, no %sW+X pages found\n",
(nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)) ?
"unexpected " : "");
return true;
}
}
#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 = 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 */
static int ptdump_cmp(const void *a, const void *b)
{
const struct addr_marker *ama = a;
const struct addr_marker *amb = b;
if (ama->start_address > amb->start_address)
return 1;
if (ama->start_address < amb->start_address)
return -1;
/*
* If the start addresses of two markers are identical sort markers in an
* order that considers areas contained within other areas correctly.
*/
if (ama->is_start && amb->is_start) {
if (ama->size > amb->size)
return -1;
if (ama->size < amb->size)
return 1;
return 0;
}
if (!ama->is_start && !amb->is_start) {
if (ama->size > amb->size)
return 1;
if (ama->size < amb->size)
return -1;
return 0;
}
if (ama->is_start)
return 1;
if (amb->is_start)
return -1;
return 0;
}
static int add_marker(unsigned long start, unsigned long end, const char *name)
{
size_t oldsize, newsize;
oldsize = markers_cnt * sizeof(*markers);
newsize = oldsize + 2 * sizeof(*markers);
if (!oldsize)
markers = kvmalloc(newsize, GFP_KERNEL);
else
markers = kvrealloc(markers, newsize, GFP_KERNEL);
if (!markers)
goto error;
markers[markers_cnt].is_start = 1;
markers[markers_cnt].start_address = start;
markers[markers_cnt].size = end - start;
markers[markers_cnt].name = name;
markers_cnt++;
markers[markers_cnt].is_start = 0;
markers[markers_cnt].start_address = end;
markers[markers_cnt].size = end - start;
markers[markers_cnt].name = name;
markers_cnt++;
return 0;
error:
markers_cnt = 0;
return -ENOMEM;
}
static int pt_dump_init(void)
{
#ifdef CONFIG_KFENCE
unsigned long kfence_start = (unsigned long)__kfence_pool;
#endif
unsigned long lowcore = (unsigned long)get_lowcore();
int rc;
/*
* 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 = (get_lowcore()->kernel_asce.val & _REGION_ENTRY_TYPE_MASK) >> 2;
max_addr = 1UL << (max_addr * 11 + 31);
/* start + end markers - must be added first */
rc = add_marker(0, -1UL, NULL);
rc |= add_marker((unsigned long)_stext, (unsigned long)_end, "Kernel Image");
rc |= add_marker(lowcore, lowcore + sizeof(struct lowcore), "Lowcore");
rc |= add_marker(__identity_base, __identity_base + ident_map_size, "Identity Mapping");
rc |= add_marker((unsigned long)__samode31, (unsigned long)__eamode31, "Amode31 Area");
rc |= add_marker(MODULES_VADDR, MODULES_END, "Modules Area");
rc |= add_marker(__abs_lowcore, __abs_lowcore + ABS_LOWCORE_MAP_SIZE, "Lowcore Area");
rc |= add_marker(__memcpy_real_area, __memcpy_real_area + MEMCPY_REAL_SIZE, "Real Memory Copy Area");
rc |= add_marker((unsigned long)vmemmap, (unsigned long)vmemmap + vmemmap_size, "vmemmap Area");
rc |= add_marker(VMALLOC_START, VMALLOC_END, "vmalloc Area");
#ifdef CONFIG_KFENCE
rc |= add_marker(kfence_start, kfence_start + KFENCE_POOL_SIZE, "KFence Pool");
#endif
#ifdef CONFIG_KMSAN
rc |= add_marker(KMSAN_VMALLOC_SHADOW_START, KMSAN_VMALLOC_SHADOW_END, "Kmsan vmalloc Shadow");
rc |= add_marker(KMSAN_VMALLOC_ORIGIN_START, KMSAN_VMALLOC_ORIGIN_END, "Kmsan vmalloc Origins");
rc |= add_marker(KMSAN_MODULES_SHADOW_START, KMSAN_MODULES_SHADOW_END, "Kmsan Modules Shadow");
rc |= add_marker(KMSAN_MODULES_ORIGIN_START, KMSAN_MODULES_ORIGIN_END, "Kmsan Modules Origins");
#endif
#ifdef CONFIG_KASAN
rc |= add_marker(KASAN_SHADOW_START, KASAN_SHADOW_END, "Kasan Shadow");
#endif
if (rc)
goto error;
sort(&markers[1], markers_cnt - 1, sizeof(*markers), ptdump_cmp, NULL);
#ifdef CONFIG_PTDUMP_DEBUGFS
debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
#endif /* CONFIG_PTDUMP_DEBUGFS */
return 0;
error:
kvfree(markers);
return -ENOMEM;
}
device_initcall(pt_dump_init);
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