s390/pgtable: add mapping statistics

Add statistics that show how memory is mapped within the kernel
identity mapping. This is more or less the same like git
commit ce0c0e50f94e ("x86, generic: CPA add statistics about state
of direct mapping v4") for x86.

I also intentionally copied the lower case "k" within DirectMap4k vs
the upper case "M" and "G" within the two other lines. Let's have
consistent inconsistencies across architectures.

The output of /proc/meminfo now contains these additional lines:

DirectMap4k:        2048 kB
DirectMap1M:     3991552 kB
DirectMap2G:     4194304 kB

The implementation on s390 is lockless unlike the x86 version, since I
assume changes to the kernel mapping are a very rare event. Therefore
it really doesn't matter if these statistics could potentially be
inconsistent if read while kernel pages tables are being changed.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 34 insertions, 0 deletions

diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c
index 91e5e29c1f5c..ba124d9c96ba 100644
--- a/arch/s390/mm/pageattr.c
+++ b/arch/s390/mm/pageattr.c
@@ -40,6 +40,20 @@ void __storage_key_init_range(unsigned long start, unsigned long end)
 }
 #endif
 
+#ifdef CONFIG_PROC_FS
+atomic_long_t direct_pages_count[PG_DIRECT_MAP_MAX];
+
+void arch_report_meminfo(struct seq_file *m)
+{
+        seq_printf(m, "DirectMap4k:    %8lu kB\n",
+                   atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_4K]) << 2);
+        seq_printf(m, "DirectMap1M:    %8lu kB\n",
+                   atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_1M]) << 10);
+        seq_printf(m, "DirectMap2G:    %8lu kB\n",
+                   atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_2G]) << 21);
+}
+#endif /* CONFIG_PROC_FS */
+
 static void pgt_set(unsigned long *old, unsigned long new, unsigned long addr,
                     unsigned long dtt)
 {
@@ -114,6 +128,8 @@ static int split_pmd_page(pmd_t *pmdp, unsigned long addr)
         }
         pmd_val(new) = __pa(pt_dir) | _SEGMENT_ENTRY;
         pgt_set((unsigned long *)pmdp, pmd_val(new), addr, CRDTE_DTT_SEGMENT);
+        update_page_count(PG_DIRECT_MAP_4K, PTRS_PER_PTE);
+        update_page_count(PG_DIRECT_MAP_1M, -1);
         return 0;
 }
 
@@ -181,6 +197,8 @@ static int split_pud_page(pud_t *pudp, unsigned long addr)
         }
         pud_val(new) = __pa(pm_dir) | _REGION3_ENTRY;
         pgt_set((unsigned long *)pudp, pud_val(new), addr, CRDTE_DTT_REGION3);
+        update_page_count(PG_DIRECT_MAP_1M, PTRS_PER_PMD);
+        update_page_count(PG_DIRECT_MAP_2G, -1);
         return 0;
 }
 
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
index b200f976c36b..a1e7c0b207e6 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -80,6 +80,7 @@ pte_t __ref *vmem_pte_alloc(void)
  */
 static int vmem_add_mem(unsigned long start, unsigned long size)
 {
+        unsigned long pages4k, pages1m, pages2g;
         unsigned long end = start + size;
         unsigned long address = start;
         pgd_t *pg_dir;
@@ -88,6 +89,7 @@ static int vmem_add_mem(unsigned long start, unsigned long size)
         pte_t *pt_dir;
         int ret = -ENOMEM;
 
+        pages4k = pages1m = pages2g = 0;
         while (address < end) {
                 pg_dir = pgd_offset_k(address);
                 if (pgd_none(*pg_dir)) {
@@ -102,6 +104,7 @@ static int vmem_add_mem(unsigned long start, unsigned long size)
                      !debug_pagealloc_enabled()) {
                         pud_val(*pu_dir) = address | pgprot_val(REGION3_KERNEL);
                         address += PUD_SIZE;
+                        pages2g++;
                         continue;
                 }
                 if (pud_none(*pu_dir)) {
@@ -116,6 +119,7 @@ static int vmem_add_mem(unsigned long start, unsigned long size)
                     !debug_pagealloc_enabled()) {
                         pmd_val(*pm_dir) = address | pgprot_val(SEGMENT_KERNEL);
                         address += PMD_SIZE;
+                        pages1m++;
                         continue;
                 }
                 if (pmd_none(*pm_dir)) {
@@ -128,9 +132,13 @@ static int vmem_add_mem(unsigned long start, unsigned long size)
                 pt_dir = pte_offset_kernel(pm_dir, address);
                 pte_val(*pt_dir) = address |  pgprot_val(PAGE_KERNEL);
                 address += PAGE_SIZE;
+                pages4k++;
         }
         ret = 0;
 out:
+        update_page_count(PG_DIRECT_MAP_4K, pages4k);
+        update_page_count(PG_DIRECT_MAP_1M, pages1m);
+        update_page_count(PG_DIRECT_MAP_2G, pages2g);
         return ret;
 }
 
@@ -140,6 +148,7 @@ out:
  */
 static void vmem_remove_range(unsigned long start, unsigned long size)
 {
+        unsigned long pages4k, pages1m, pages2g;
         unsigned long end = start + size;
         unsigned long address = start;
         pgd_t *pg_dir;
@@ -147,6 +156,7 @@ static void vmem_remove_range(unsigned long start, unsigned long size)
         pmd_t *pm_dir;
         pte_t *pt_dir;
 
+        pages4k = pages1m = pages2g = 0;
         while (address < end) {
                 pg_dir = pgd_offset_k(address);
                 if (pgd_none(*pg_dir)) {
@@ -161,6 +171,7 @@ static void vmem_remove_range(unsigned long start, unsigned long size)
                 if (pud_large(*pu_dir)) {
                         pud_clear(pu_dir);
                         address += PUD_SIZE;
+                        pages2g++;
                         continue;
                 }
                 pm_dir = pmd_offset(pu_dir, address);
@@ -171,13 +182,18 @@ static void vmem_remove_range(unsigned long start, unsigned long size)
                 if (pmd_large(*pm_dir)) {
                         pmd_clear(pm_dir);
                         address += PMD_SIZE;
+                        pages1m++;
                         continue;
                 }
                 pt_dir = pte_offset_kernel(pm_dir, address);
                 pte_clear(&init_mm, address, pt_dir);
                 address += PAGE_SIZE;
+                pages4k++;
         }
         flush_tlb_kernel_range(start, end);
+        update_page_count(PG_DIRECT_MAP_4K, -pages4k);
+        update_page_count(PG_DIRECT_MAP_1M, -pages1m);
+        update_page_count(PG_DIRECT_MAP_2G, -pages2g);
 }
 
 /*