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Commit a1c843b8 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/mm: change swap pte encoding and pgtable cleanup 



After the file ptes have been removed the bit combination used to
encode non-linear mappings can be reused for the swap ptes. This
frees up a precious pte software bit. Reflect the change in the
swap encoding in the comments and do some cleanup while we are
at it.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent b7d14f3a

arch/s390/include/asm/pgtable.h

+63 −95
Original line number Diff line number Diff line
@@ -12,12 +12,9 @@ 
#define _ASM_S390_PGTABLE_H



/*

 * The Linux memory management assumes a three-level page table setup. For

 * s390 31 bit we "fold" the mid level into the top-level page table, so

 * that we physically have the same two-level page table as the s390 mmu

 * expects in 31 bit mode. For s390 64 bit we use three of the five levels

 * the hardware provides (region first and region second tables are not

 * used).

 * The Linux memory management assumes a three-level page table setup.

 * For s390 64 bit we use up to four of the five levels the hardware

 * provides (region first tables are not used).

 *

 * The "pgd_xxx()" functions are trivial for a folded two-level

 * setup: the pgd is never bad, and a pmd always exists (as it's folded
@@ -101,8 +98,8 @@ extern unsigned long zero_page_mask; 


#ifndef __ASSEMBLY__

/*

 * The vmalloc and module area will always be on the topmost area of the kernel

 * mapping. We reserve 96MB (31bit) / 128GB (64bit) for vmalloc and modules.

 * The vmalloc and module area will always be on the topmost area of the

 * kernel mapping. We reserve 128GB (64bit) for vmalloc and modules.

 * On 64 bit kernels we have a 2GB area at the top of the vmalloc area where

 * modules will reside. That makes sure that inter module branches always

 * happen without trampolines and in addition the placement within a 2GB frame
@@ -131,38 +128,6 @@ static inline int is_module_addr(void *addr) 
}



/*

 * A 31 bit pagetable entry of S390 has following format:

 *  |   PFRA          |    |  OS  |

 * 0                   0IP0

 * 00000000001111111111222222222233

 * 01234567890123456789012345678901

 *

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

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

 *

 * A 31 bit segmenttable entry of S390 has following format:

 *  |   P-table origin      |  |PTL

 * 0                         IC

 * 00000000001111111111222222222233

 * 01234567890123456789012345678901

 *

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

 * C Common-Segment Bit:     Segment is not private (PoP 3-30)

 * PTL Page-Table-Length:    Page-table length (PTL+1*16 entries -> up to 256)

 *

 * The 31 bit segmenttable origin of S390 has following format:

 *

 *  |S-table origin   |     | STL |

 * X                   **GPS

 * 00000000001111111111222222222233

 * 01234567890123456789012345678901

 *

 * X Space-Switch event:

 * G Segment-Invalid Bit:     *

 * P Private-Space Bit:       Segment is not private (PoP 3-30)

 * S Storage-Alteration:

 * 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			      |0IPC|  OS  |

 * 0000000000111111111122222222223333333333444444444455555555556666
@@ -220,7 +185,6 @@ static inline int is_module_addr(void *addr) 


/* Software bits in the page table entry */

#define _PAGE_PRESENT	0x001		/* SW pte present bit */

#define _PAGE_TYPE	0x002		/* SW pte type bit */

#define _PAGE_YOUNG	0x004		/* SW pte young bit */

#define _PAGE_DIRTY	0x008		/* SW pte dirty bit */

#define _PAGE_READ	0x010		/* SW pte read bit */
@@ -240,31 +204,34 @@ static inline int is_module_addr(void *addr) 
 * table lock held.

 *

 * The following table gives the different possible bit combinations for

 * the pte hardware and software bits in the last 12 bits of a pte:

 * the pte hardware and software bits in the last 12 bits of a pte

 * (. unassigned bit, x don't care, t swap type):

 *

 *				842100000000

 *				000084210000

 *				000000008421

 *				.IR...wrdytp

 * empty			.10...000000

 * swap				.10...xxxx10

 * file				.11...xxxxx0

 * prot-none, clean, old	.11...000001

 * prot-none, clean, young	.11...000101

 * prot-none, dirty, old	.10...001001

 * prot-none, dirty, young	.10...001101

 * read-only, clean, old	.11...010001

 * read-only, clean, young	.01...010101

 * read-only, dirty, old	.11...011001

 * read-only, dirty, young	.01...011101

 * read-write, clean, old	.11...110001

 * read-write, clean, young	.01...110101

 * read-write, dirty, old	.10...111001

 * read-write, dirty, young	.00...111101

 *				.IR.uswrdy.p

 * empty			.10.00000000

 * swap				.11..ttttt.0

 * prot-none, clean, old	.11.xx0000.1

 * prot-none, clean, young	.11.xx0001.1

 * prot-none, dirty, old	.10.xx0010.1

 * prot-none, dirty, young	.10.xx0011.1

 * read-only, clean, old	.11.xx0100.1

 * read-only, clean, young	.01.xx0101.1

 * read-only, dirty, old	.11.xx0110.1

 * read-only, dirty, young	.01.xx0111.1

 * read-write, clean, old	.11.xx1100.1

 * read-write, clean, young	.01.xx1101.1

 * read-write, dirty, old	.10.xx1110.1

 * read-write, dirty, young	.00.xx1111.1

 * HW-bits: R read-only, I invalid

 * SW-bits: p present, y young, d dirty, r read, w write, s special,

 *	    u unused, l large

 *

 * pte_present is true for the bit pattern .xx...xxxxx1, (pte & 0x001) == 0x001

 * pte_none    is true for the bit pattern .10...xxxx00, (pte & 0x603) == 0x400

 * pte_swap    is true for the bit pattern .10...xxxx10, (pte & 0x603) == 0x402

 * pte_none    is true for the bit pattern .10.00000000, pte == 0x400

 * pte_swap    is true for the bit pattern .11..ooooo.0, (pte & 0x201) == 0x200

 * pte_present is true for the bit pattern .xx.xxxxxx.1, (pte & 0x001) == 0x001

 */



/* Bits in the segment/region table address-space-control-element */
@@ -335,6 +302,8 @@ static inline int is_module_addr(void *addr) 
 * read-write, dirty, young	11..0...0...11

 * The segment table origin is used to distinguish empty (origin==0) from

 * read-write, old segment table entries (origin!=0)

 * HW-bits: R read-only, I invalid

 * SW-bits: y young, d dirty, r read, w write

 */



#define _SEGMENT_ENTRY_SPLIT_BIT 11	/* THP splitting bit number */
@@ -591,10 +560,9 @@ static inline int pte_none(pte_t pte) 


static inline int pte_swap(pte_t pte)

{

	/* Bit pattern: (pte & 0x603) == 0x402 */

	return (pte_val(pte) & (_PAGE_INVALID | _PAGE_PROTECT |

				_PAGE_TYPE | _PAGE_PRESENT))

		== (_PAGE_INVALID | _PAGE_TYPE);

	/* Bit pattern: (pte & 0x201) == 0x200 */

	return (pte_val(pte) & (_PAGE_PROTECT | _PAGE_PRESENT))

		== _PAGE_PROTECT;

}



static inline int pte_special(pte_t pte)
@@ -1595,51 +1563,51 @@ static inline int has_transparent_hugepage(void) 
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */



/*

 * 31 bit swap entry format:

 * A page-table entry has some bits we have to treat in a special way.

 * Bits 0, 20 and bit 23 have to be zero, otherwise an specification

 * exception will occur instead of a page translation exception. The

 * specifiation exception has the bad habit not to store necessary

 * information in the lowcore.

 * Bits 21, 22, 30 and 31 are used to indicate the page type.

 * A swap pte is indicated by bit pattern (pte & 0x603) == 0x402

 * This leaves the bits 1-19 and bits 24-29 to store type and offset.

 * We use the 5 bits from 25-29 for the type and the 20 bits from 1-19

 * plus 24 for the offset.

 * 0|     offset        |0110|o|type |00|

 * 0 0000000001111111111 2222 2 22222 33

 * 0 1234567890123456789 0123 4 56789 01

 *

 * 64 bit swap entry format:

 * A page-table entry has some bits we have to treat in a special way.

 * Bits 52 and bit 55 have to be zero, otherwise an specification

 * exception will occur instead of a page translation exception. The

 * specifiation exception has the bad habit not to store necessary

 * information in the lowcore.

 * Bits 53, 54, 62 and 63 are used to indicate the page type.

 * A swap pte is indicated by bit pattern (pte & 0x603) == 0x402

 * This leaves the bits 0-51 and bits 56-61 to store type and offset.

 * We use the 5 bits from 57-61 for the type and the 53 bits from 0-51

 * plus 56 for the offset.

 * |                      offset                        |0110|o|type |00|

 *  0000000000111111111122222222223333333333444444444455 5555 5 55566 66

 *  0123456789012345678901234567890123456789012345678901 2345 6 78901 23

 * Bits 54 and 63 are used to indicate the page type.

 * A swap pte is indicated by bit pattern (pte & 0x201) == 0x200

 * This leaves the bits 0-51 and bits 56-62 to store type and offset.

 * We use the 5 bits from 57-61 for the type and the 52 bits from 0-51

 * for the offset.

 * |			  offset			|01100|type |00|

 * |0000000000111111111122222222223333333333444444444455|55555|55566|66|

 * |0123456789012345678901234567890123456789012345678901|23456|78901|23|

 */



#define __SWP_OFFSET_MASK (~0UL >> 11)

#define __SWP_OFFSET_MASK	((1UL << 52) - 1)

#define __SWP_OFFSET_SHIFT	12

#define __SWP_TYPE_MASK		((1UL << 5) - 1)

#define __SWP_TYPE_SHIFT	2



static inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)

{

	pte_t pte;

	offset &= __SWP_OFFSET_MASK;

	pte_val(pte) = _PAGE_INVALID | _PAGE_TYPE | ((type & 0x1f) << 2) |

		((offset & 1UL) << 7) | ((offset & ~1UL) << 11);



	pte_val(pte) = _PAGE_INVALID | _PAGE_PROTECT;

	pte_val(pte) |= (offset & __SWP_OFFSET_MASK) << __SWP_OFFSET_SHIFT;

	pte_val(pte) |= (type & __SWP_TYPE_MASK) << __SWP_TYPE_SHIFT;

	return pte;

}



#define __swp_type(entry)	(((entry).val >> 2) & 0x1f)

#define __swp_offset(entry)	(((entry).val >> 11) | (((entry).val >> 7) & 1))

#define __swp_entry(type,offset) ((swp_entry_t) { pte_val(mk_swap_pte((type),(offset))) })

static inline unsigned long __swp_type(swp_entry_t entry)

{

	return (entry.val >> __SWP_TYPE_SHIFT) & __SWP_TYPE_MASK;

}



static inline unsigned long __swp_offset(swp_entry_t entry)

{

	return (entry.val >> __SWP_OFFSET_SHIFT) & __SWP_OFFSET_MASK;

}



static inline swp_entry_t __swp_entry(unsigned long type, unsigned long offset)

{

	return (swp_entry_t) { pte_val(mk_swap_pte(type, offset)) };

}



#define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })

#define __swp_entry_to_pte(x)	((pte_t) { (x).val })

arch/s390/mm/hugetlbpage.c

+34 −28
Original line number Diff line number Diff line
@@ -14,20 +14,23 @@ static inline pmd_t __pte_to_pmd(pte_t pte) 


	/*

	 * Convert encoding		  pte bits	   pmd bits

	 *				.IR...wrdytp	dy..R...I...wr

	 * empty			.10...000000 -> 00..0...1...00

	 * prot-none, clean, old	.11...000001 -> 00..1...1...00

	 * prot-none, clean, young	.11...000101 -> 01..1...1...00

	 * prot-none, dirty, old	.10...001001 -> 10..1...1...00

	 * prot-none, dirty, young	.10...001101 -> 11..1...1...00

	 * read-only, clean, old	.11...010001 -> 00..1...1...01

	 * read-only, clean, young	.01...010101 -> 01..1...0...01

	 * read-only, dirty, old	.11...011001 -> 10..1...1...01

	 * read-only, dirty, young	.01...011101 -> 11..1...0...01

	 * read-write, clean, old	.11...110001 -> 00..0...1...11

	 * read-write, clean, young	.01...110101 -> 01..0...0...11

	 * read-write, dirty, old	.10...111001 -> 10..0...1...11

	 * read-write, dirty, young	.00...111101 -> 11..0...0...11

	 *				lIR.uswrdy.p	dy..R...I...wr

	 * empty			010.000000.0 -> 00..0...1...00

	 * prot-none, clean, old	111.000000.1 -> 00..1...1...00

	 * prot-none, clean, young	111.000001.1 -> 01..1...1...00

	 * prot-none, dirty, old	111.000010.1 -> 10..1...1...00

	 * prot-none, dirty, young	111.000011.1 -> 11..1...1...00

	 * read-only, clean, old	111.000100.1 -> 00..1...1...01

	 * read-only, clean, young	101.000101.1 -> 01..1...0...01

	 * read-only, dirty, old	111.000110.1 -> 10..1...1...01

	 * read-only, dirty, young	101.000111.1 -> 11..1...0...01

	 * read-write, clean, old	111.001100.1 -> 00..1...1...11

	 * read-write, clean, young	101.001101.1 -> 01..1...0...11

	 * read-write, dirty, old	110.001110.1 -> 10..0...1...11

	 * read-write, dirty, young	100.001111.1 -> 11..0...0...11

	 * HW-bits: R read-only, I invalid

	 * SW-bits: p present, y young, d dirty, r read, w write, s special,

	 *	    u unused, l large

	 */

	if (pte_present(pte)) {

		pmd_val(pmd) = pte_val(pte) & PAGE_MASK;
@@ -48,20 +51,23 @@ static inline pte_t __pmd_to_pte(pmd_t pmd) 


	/*

	 * Convert encoding		   pmd bits	    pte bits

	 *				dy..R...I...wr	  .IR...wrdytp

	 * empty			00..0...1...00 -> .10...001100

	 * prot-none, clean, old	00..0...1...00 -> .10...000001

	 * prot-none, clean, young	01..0...1...00 -> .10...000101

	 * prot-none, dirty, old	10..0...1...00 -> .10...001001

	 * prot-none, dirty, young	11..0...1...00 -> .10...001101

	 * read-only, clean, old	00..1...1...01 -> .11...010001

	 * read-only, clean, young	01..1...1...01 -> .11...010101

	 * read-only, dirty, old	10..1...1...01 -> .11...011001

	 * read-only, dirty, young	11..1...1...01 -> .11...011101

	 * read-write, clean, old	00..0...1...11 -> .10...110001

	 * read-write, clean, young	01..0...1...11 -> .10...110101

	 * read-write, dirty, old	10..0...1...11 -> .10...111001

	 * read-write, dirty, young	11..0...1...11 -> .10...111101

	 *				dy..R...I...wr	  lIR.uswrdy.p

	 * empty			00..0...1...00 -> 010.000000.0

	 * prot-none, clean, old	00..1...1...00 -> 111.000000.1

	 * prot-none, clean, young	01..1...1...00 -> 111.000001.1

	 * prot-none, dirty, old	10..1...1...00 -> 111.000010.1

	 * prot-none, dirty, young	11..1...1...00 -> 111.000011.1

	 * read-only, clean, old	00..1...1...01 -> 111.000100.1

	 * read-only, clean, young	01..1...0...01 -> 101.000101.1

	 * read-only, dirty, old	10..1...1...01 -> 111.000110.1

	 * read-only, dirty, young	11..1...0...01 -> 101.000111.1

	 * read-write, clean, old	00..1...1...11 -> 111.001100.1

	 * read-write, clean, young	01..1...0...11 -> 101.001101.1

	 * read-write, dirty, old	10..0...1...11 -> 110.001110.1

	 * read-write, dirty, young	11..0...0...11 -> 100.001111.1

	 * HW-bits: R read-only, I invalid

	 * SW-bits: p present, y young, d dirty, r read, w write, s special,

	 *	    u unused, l large

	 */

	if (pmd_present(pmd)) {

		pte_val(pte) = pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN_LARGE;