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Commit 6a985c61 authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Martin Schwidefsky
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[S390] s390: use change recording override for kernel mapping 



We dont need the dirty bit if a write access is done via the kernel
mapping. In that case SetPageDirty and friends are used anyway, no
need to do that a second time. We can use the change-recording
overide function for the kernel mapping, if available.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent a968cd3e

arch/s390/include/asm/pgtable.h

+3 −1
Original line number Diff line number Diff line
@@ -169,12 +169,13 @@ extern unsigned long VMALLOC_START; 
 * STL Segment-Table-Length:  Segment-table length (STL+1*16 entries -> up to 2048)

 *

 * A 64 bit pagetable entry of S390 has following format:

 * |                     PFRA                         |0IP0|  OS  |

 * |			 PFRA			      |0IPC|  OS  |

 * 0000000000111111111122222222223333333333444444444455555555556666

 * 0123456789012345678901234567890123456789012345678901234567890123

 *

 * I Page-Invalid Bit:    Page is not available for address-translation

 * P Page-Protection Bit: Store access not possible for page

 * C Change-bit override: HW is not required to set change bit

 *

 * A 64 bit segmenttable entry of S390 has following format:

 * |        P-table origin                              |      TT
@@ -218,6 +219,7 @@ extern unsigned long VMALLOC_START; 
 */



/* Hardware bits in the page table entry */

#define _PAGE_CO	0x100		/* HW Change-bit override */

#define _PAGE_RO	0x200		/* HW read-only bit  */

#define _PAGE_INVALID	0x400		/* HW invalid bit    */

arch/s390/mm/vmem.c

+8 −3
Original line number Diff line number Diff line
@@ -70,6 +70,10 @@ static pte_t __ref *vmem_pte_alloc(void) 
		pte = alloc_bootmem(PTRS_PER_PTE * sizeof(pte_t));

	if (!pte)

		return NULL;

	if (MACHINE_HAS_HPAGE)

		clear_table((unsigned long *) pte, _PAGE_TYPE_EMPTY | _PAGE_CO,

			    PTRS_PER_PTE * sizeof(pte_t));

	else

		clear_table((unsigned long *) pte, _PAGE_TYPE_EMPTY,

			    PTRS_PER_PTE * sizeof(pte_t));

	return pte;
@@ -112,7 +116,8 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro) 
		if (MACHINE_HAS_HPAGE && !(address & ~HPAGE_MASK) &&

		    (address + HPAGE_SIZE <= start + size) &&

		    (address >= HPAGE_SIZE)) {

			pte_val(pte) |= _SEGMENT_ENTRY_LARGE;

			pte_val(pte) |= _SEGMENT_ENTRY_LARGE |

					_SEGMENT_ENTRY_CO;

			pmd_val(*pm_dir) = pte_val(pte);

			address += HPAGE_SIZE - PAGE_SIZE;

			continue;