v4.19.13 snapshot.
diff --git a/arch/s390/mm/dump_pagetables.c b/arch/s390/mm/dump_pagetables.c
new file mode 100644
index 0000000..7cdea2e
--- /dev/null
+++ b/arch/s390/mm/dump_pagetables.c
@@ -0,0 +1,249 @@
+// 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/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,
+ 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"},
+ [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);