s390/mm,ptdump: convert to generic page table dumper

Make use of generic ptdump infrastructure.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/Kconfig

@@ -120,6 +120,7 @@ config S390
 	select GENERIC_CPU_VULNERABILITIES
 	select GENERIC_FIND_FIRST_BIT
 	select GENERIC_GETTIMEOFDAY
+	select GENERIC_PTDUMP
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
 	select HAVE_ALIGNED_STRUCT_PAGE if SLUB

arch/s390/Kconfig.debug

@@ -3,17 +3,5 @@
 config TRACE_IRQFLAGS_SUPPORT
 	def_bool y
 
-config S390_PTDUMP
-	bool "Export kernel pagetable layout to userspace via debugfs"
-	depends on DEBUG_KERNEL
-	select DEBUG_FS
-	help
-	  Say Y here if you want to show the kernel pagetable layout in a
-	  debugfs file. This information is only useful for kernel developers
-	  who are working in architecture specific areas of the kernel.
-	  It is probably not a good idea to enable this feature in a production
-	  kernel.
-	  If in doubt, say "N"
-
 config EARLY_PRINTK
 	def_bool y

arch/s390/configs/debug_defconfig

@@ -774,6 +774,7 @@ CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_PAGEALLOC=y
 CONFIG_PAGE_OWNER=y
 CONFIG_DEBUG_RODATA_TEST=y
+CONFIG_PTDUMP_DEBUGFS=y
 CONFIG_DEBUG_OBJECTS=y
 CONFIG_DEBUG_OBJECTS_SELFTEST=y
 CONFIG_DEBUG_OBJECTS_FREE=y
@@ -819,7 +820,6 @@ CONFIG_SCHED_TRACER=y
 CONFIG_FTRACE_SYSCALLS=y
 CONFIG_BLK_DEV_IO_TRACE=y
 CONFIG_HIST_TRIGGERS=y
-CONFIG_S390_PTDUMP=y
 CONFIG_NOTIFIER_ERROR_INJECTION=m
 CONFIG_NETDEV_NOTIFIER_ERROR_INJECT=m
 CONFIG_FAULT_INJECTION=y

arch/s390/configs/defconfig

@@ -758,6 +758,7 @@ CONFIG_GDB_SCRIPTS=y
 CONFIG_FRAME_WARN=1024
 CONFIG_DEBUG_SECTION_MISMATCH=y
 CONFIG_MAGIC_SYSRQ=y
+CONFIG_PTDUMP_DEBUGFS=y
 CONFIG_DEBUG_MEMORY_INIT=y
 CONFIG_PANIC_ON_OOPS=y
 CONFIG_TEST_LOCKUP=m
@@ -772,7 +773,6 @@ CONFIG_SCHED_TRACER=y
 CONFIG_FTRACE_SYSCALLS=y
 CONFIG_BLK_DEV_IO_TRACE=y
 CONFIG_HIST_TRIGGERS=y
-CONFIG_S390_PTDUMP=y
 CONFIG_LKDTM=m
 CONFIG_PERCPU_TEST=m
 CONFIG_ATOMIC64_SELFTEST=y

arch/s390/mm/Makefile

@@ -8,7 +8,7 @@ obj-y		+= page-states.o pageattr.o pgtable.o pgalloc.o
 
 obj-$(CONFIG_CMM)		+= cmm.o
 obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
-obj-$(CONFIG_S390_PTDUMP)	+= dump_pagetables.o
+obj-$(CONFIG_PTDUMP_DEBUGFS)	+= dump_pagetables.o
 obj-$(CONFIG_PGSTE)		+= gmap.o
 
 KASAN_SANITIZE_kasan_init.o	:= n

arch/s390/mm/dump_pagetables.c

 // SPDX-License-Identifier: GPL-2.0
+#include <linux/ptdump.h>
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
-#include <linux/sched.h>
 #include <linux/mm.h>
 #include <linux/kasan.h>
 #include <asm/kasan.h>
@@ -42,10 +42,11 @@ static struct addr_marker address_markers[] = {
 };
 
 struct pg_state {
+	struct ptdump_state ptdump;
+	struct seq_file *seq;
 	int level;
 	unsigned int current_prot;
 	unsigned long start_address;
-	unsigned long current_address;
 	const struct addr_marker *marker;
 };
 
@@ -63,215 +64,75 @@ static void print_prot(struct seq_file *m, unsigned int pr, int level)
 	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 void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
 {
-	static const char units[] = "KMGTPE";
 	int width = sizeof(unsigned long) * 2;
+	static const char units[] = "KMGTPE";
 	const char *unit = units;
-	unsigned int prot, cur;
 	unsigned long delta;
+	struct pg_state *st;
+	struct seq_file *m;
+	unsigned int prot;
 
-	/*
-	 * 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;
+	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) {
 		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 */
+		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) {
 		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;
+			   width, addr);
+		delta = (addr - 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);
-		while (st->current_address >= st->marker[1].start_address) {
+		while (addr >= 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->start_address = addr;
+		st->current_prot = prot;
 		st->level = level;
 	}
 }
 
-#ifdef CONFIG_KASAN
-static void note_kasan_early_shadow_page(struct seq_file *m,
-						struct pg_state *st)
-{
-	unsigned int prot;
-
-	prot = pte_val(*kasan_early_shadow_pte) &
-		(_PAGE_PROTECT | _PAGE_INVALID | _PAGE_NOEXEC);
-	note_page(m, st, prot, 4);
-}
-#endif
-
-/*
- * 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;
-
-#ifdef CONFIG_KASAN
-	if ((pud_val(*pud) & PAGE_MASK) == __pa(kasan_early_shadow_pmd)) {
-		note_kasan_early_shadow_page(m, st);
-		return;
-	}
-#endif
-
-	pmd = pmd_offset(pud, addr);
-	for (i = 0; i < PTRS_PER_PMD && addr < max_addr; i++, pmd++) {
-		st->current_address = 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;
-
-#ifdef CONFIG_KASAN
-	if ((p4d_val(*p4d) & PAGE_MASK) == __pa(kasan_early_shadow_pud)) {
-		note_kasan_early_shadow_page(m, st);
-		return;
-	}
-#endif
-
-	pud = pud_offset(p4d, addr);
-	for (i = 0; i < PTRS_PER_PUD && addr < max_addr; i++, pud++) {
-		st->current_address = 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;
-
-#ifdef CONFIG_KASAN
-	if ((pgd_val(*pgd) & PAGE_MASK) == __pa(kasan_early_shadow_p4d)) {
-		note_kasan_early_shadow_page(m, st);
-		return;
-	}
-#endif
-
-	p4d = p4d_offset(pgd, addr);
-	for (i = 0; i < PTRS_PER_P4D && addr < max_addr; i++, p4d++) {
-		st->current_address = 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);
+	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,
+		.start_address = 0,
+		.marker = address_markers,
+	};
+
+	ptdump_walk_pgd(&st.ptdump, &init_mm, 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,
-};
+DEFINE_SHOW_ATTRIBUTE(ptdump);
 
 static int pt_dump_init(void)
 {