s390/mm: fix direct map accounting

Commit bb1520d5 ("s390/mm: start kernel with DAT enabled") did not
implement direct map accounting in the early page table setup code. In
result the reported values are bogus now:

$cat /proc/meminfo
...
DirectMap4k:        5120 kB
DirectMap1M:    18446744073709546496 kB
DirectMap2G:           0 kB

Fix this by adding the missing accounting. The result looks sane again:

$cat /proc/meminfo
...
DirectMap4k:        6156 kB
DirectMap1M:     2091008 kB
DirectMap2G:     6291456 kB

Fixes: bb1520d5 ("s390/mm: start kernel with DAT enabled")
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/boot/vmem.c

@@ -13,6 +13,10 @@
 
 unsigned long __bootdata_preserved(s390_invalid_asce);
 
+#ifdef CONFIG_PROC_FS
+atomic_long_t __bootdata_preserved(direct_pages_count[PG_DIRECT_MAP_MAX]);
+#endif
+
 #define init_mm			(*(struct mm_struct *)vmlinux.init_mm_off)
 #define swapper_pg_dir		vmlinux.swapper_pg_dir_off
 #define invalid_pg_dir		vmlinux.invalid_pg_dir_off
@@ -267,6 +271,7 @@ static bool can_large_pmd(pmd_t *pm_dir, unsigned long addr, unsigned long end)
 static void pgtable_pte_populate(pmd_t *pmd, unsigned long addr, unsigned long end,
 				 enum populate_mode mode)
 {
+	unsigned long pages = 0;
 	pte_t *pte, entry;
 
 	pte = pte_offset_kernel(pmd, addr);
@@ -277,14 +282,17 @@ static void pgtable_pte_populate(pmd_t *pmd, unsigned long addr, unsigned long e
 			entry = __pte(_pa(addr, PAGE_SIZE, mode));
 			entry = set_pte_bit(entry, PAGE_KERNEL_EXEC);
 			set_pte(pte, entry);
+			pages++;
 		}
 	}
+	if (mode == POPULATE_DIRECT)
+		update_page_count(PG_DIRECT_MAP_4K, pages);
 }
 
 static void pgtable_pmd_populate(pud_t *pud, unsigned long addr, unsigned long end,
 				 enum populate_mode mode)
 {
-	unsigned long next;
+	unsigned long next, pages = 0;
 	pmd_t *pmd, entry;
 	pte_t *pte;
 
@@ -298,6 +306,7 @@ static void pgtable_pmd_populate(pud_t *pud, unsigned long addr, unsigned long e
 				entry = __pmd(_pa(addr, _SEGMENT_SIZE, mode));
 				entry = set_pmd_bit(entry, SEGMENT_KERNEL_EXEC);
 				set_pmd(pmd, entry);
+				pages++;
 				continue;
 			}
 			pte = boot_pte_alloc();
@@ -307,12 +316,14 @@ static void pgtable_pmd_populate(pud_t *pud, unsigned long addr, unsigned long e
 		}
 		pgtable_pte_populate(pmd, addr, next, mode);
 	}
+	if (mode == POPULATE_DIRECT)
+		update_page_count(PG_DIRECT_MAP_1M, pages);
 }
 
 static void pgtable_pud_populate(p4d_t *p4d, unsigned long addr, unsigned long end,
 				 enum populate_mode mode)
 {
-	unsigned long next;
+	unsigned long next, pages = 0;
 	pud_t *pud, entry;
 	pmd_t *pmd;
 
@@ -326,6 +337,7 @@ static void pgtable_pud_populate(p4d_t *p4d, unsigned long addr, unsigned long e
 				entry = __pud(_pa(addr, _REGION3_SIZE, mode));
 				entry = set_pud_bit(entry, REGION3_KERNEL_EXEC);
 				set_pud(pud, entry);
+				pages++;
 				continue;
 			}
 			pmd = boot_crst_alloc(_SEGMENT_ENTRY_EMPTY);
@@ -335,6 +347,8 @@ static void pgtable_pud_populate(p4d_t *p4d, unsigned long addr, unsigned long e
 		}
 		pgtable_pmd_populate(pud, addr, next, mode);
 	}
+	if (mode == POPULATE_DIRECT)
+		update_page_count(PG_DIRECT_MAP_2G, pages);
 }
 
 static void pgtable_p4d_populate(pgd_t *pgd, unsigned long addr, unsigned long end,

arch/s390/include/asm/pgtable.h

@@ -34,7 +34,7 @@ enum {
 	PG_DIRECT_MAP_MAX
 };
 
-extern atomic_long_t direct_pages_count[PG_DIRECT_MAP_MAX];
+extern atomic_long_t __bootdata_preserved(direct_pages_count[PG_DIRECT_MAP_MAX]);
 
 static inline void update_page_count(int level, long count)
 {

arch/s390/mm/pageattr.c

@@ -41,7 +41,7 @@ void __storage_key_init_range(unsigned long start, unsigned long end)
 }
 
 #ifdef CONFIG_PROC_FS
-atomic_long_t direct_pages_count[PG_DIRECT_MAP_MAX];
+atomic_long_t __bootdata_preserved(direct_pages_count[PG_DIRECT_MAP_MAX]);
 
 void arch_report_meminfo(struct seq_file *m)
 {