s390/mm/ptdump: Add support for relocated lowcore mapping

The page table dumper contains a hard coded assumption that the first
mapped area starts at address zero. With a relocated lowcore this is
not true anymore. Subsequently the first entry (lowcore) is printed as
if it would contain everything from address zero until the end of the
location of the lowcore area.

Fix this by adding a single "Kernel Virtual Address Space" entry,
which always starts at address zero. It ends when the lowcore area
starts which is either address zero, or its relocated address.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/mm/dump_pagetables.c

@@ -20,7 +20,8 @@ struct addr_marker {
 };
 
 enum address_markers_idx {
-	LOWCORE_START_NR = 0,
+	KVA_NR = 0,
+	LOWCORE_START_NR,
 	LOWCORE_END_NR,
 	AMODE31_START_NR,
 	AMODE31_END_NR,
@@ -59,6 +60,7 @@ enum address_markers_idx {
 };
 
 static struct addr_marker address_markers[] = {
+	[KVA_NR]		= {0, "Kernel Virtual Address Space"},
 	[LOWCORE_START_NR]	= {0, "Lowcore Start"},
 	[LOWCORE_END_NR]	= {0, "Lowcore End"},
 	[IDENTITY_START_NR]	= {0, "Identity Mapping Start"},
@@ -163,6 +165,19 @@ static void note_prot_wx(struct pg_state *st, unsigned long addr)
 	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 ]---\n", st->marker->name);
+	}
+	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;
@@ -186,9 +201,7 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
 		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;
+		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);
@@ -202,13 +215,7 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
 		}
 		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;
+		note_page_update_state(st, addr, prot, level);
 	}
 }
 
@@ -303,6 +310,8 @@ 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();
+
 	/*
 	 * Figure out the maximum virtual address being accessible with the
 	 * kernel ASCE. We need this to keep the page table walker functions
@@ -310,8 +319,8 @@ static int pt_dump_init(void)
 	 */
 	max_addr = (get_lowcore()->kernel_asce.val & _REGION_ENTRY_TYPE_MASK) >> 2;
 	max_addr = 1UL << (max_addr * 11 + 31);
-	address_markers[LOWCORE_START_NR].start_address = 0;
-	address_markers[LOWCORE_END_NR].start_address = sizeof(struct lowcore);
+	address_markers[LOWCORE_START_NR].start_address = lowcore;
+	address_markers[LOWCORE_END_NR].start_address = lowcore + sizeof(struct lowcore);
 	address_markers[IDENTITY_START_NR].start_address = __identity_base;
 	address_markers[IDENTITY_END_NR].start_address = __identity_base + ident_map_size;
 	address_markers[AMODE31_START_NR].start_address = (unsigned long)__samode31;