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Commit 37cd944c authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

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 ce0c0e50 ("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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent bab247ff

arch/s390/include/asm/pgtable.h

+19 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/mm_types.h>

#include <linux/page-flags.h>

#include <linux/radix-tree.h>

#include <linux/atomic.h>

#include <asm/bug.h>

#include <asm/page.h>
@@ -37,6 +38,24 @@ extern void vmem_map_init(void); 
pmd_t *vmem_pmd_alloc(void);

pte_t *vmem_pte_alloc(void);



enum {

	PG_DIRECT_MAP_4K = 0,

	PG_DIRECT_MAP_1M,

	PG_DIRECT_MAP_2G,

	PG_DIRECT_MAP_MAX

};



extern atomic_long_t direct_pages_count[PG_DIRECT_MAP_MAX];



static inline void update_page_count(int level, long count)

{

	if (IS_ENABLED(CONFIG_PROC_FS))

		atomic_long_add(count, &direct_pages_count[level]);

}



struct seq_file;

void arch_report_meminfo(struct seq_file *m);



/*

 * The S390 doesn't have any external MMU info: the kernel page

 * tables contain all the necessary information.

arch/s390/mm/pageattr.c

+18 −0
Original line number Diff line number Diff line
@@ -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;

}

arch/s390/mm/vmem.c

+16 −0
Original line number Diff line number Diff line
@@ -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 @@ static int vmem_add_mem(unsigned long start, unsigned long size) 
 */

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);

}



/*