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linux-pinenote/arch/s390/mm/hugetlbpage.c
Martin Schwidefsky 152125b7a8 s390/mm: implement dirty bits for large segment table entries 
The large segment table entry format has block of bits for the
ACC/F values for the large page. These bits are valid only if
another bit (AV bit 0x10000) of the segment table entry is set.
The ACC/F bits do not have a meaning if the AV bit is off.
This allows to put the THP splitting bit, the segment young bit
and the new segment dirty bit into the ACC/F bits as long as
the AV bit stays off. The dirty and young information is only
available if the pmd is large.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-08-01 14:55:05 +02:00

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/*
* IBM System z Huge TLB Page Support for Kernel.
*
* Copyright IBM Corp. 2007
* Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
*/
#include <linux/mm.h>
#include <linux/hugetlb.h>
static inline pmd_t __pte_to_pmd(pte_t pte)
{
pmd_t pmd;
/*
* 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
*/
if (pte_present(pte)) {
pmd_val(pmd) = pte_val(pte) & PAGE_MASK;
pmd_val(pmd) |= (pte_val(pte) & _PAGE_READ) >> 4;
pmd_val(pmd) |= (pte_val(pte) & _PAGE_WRITE) >> 4;
pmd_val(pmd) |= (pte_val(pte) & _PAGE_INVALID) >> 5;
pmd_val(pmd) |= (pte_val(pte) & _PAGE_PROTECT);
pmd_val(pmd) |= (pte_val(pte) & _PAGE_DIRTY) << 10;
pmd_val(pmd) |= (pte_val(pte) & _PAGE_YOUNG) << 10;
} else
pmd_val(pmd) = _SEGMENT_ENTRY_INVALID;
return pmd;
}
static inline pte_t __pmd_to_pte(pmd_t pmd)
{
pte_t pte;
/*
* 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
*/
if (pmd_present(pmd)) {
pte_val(pte) = pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN_LARGE;
pte_val(pte) |= _PAGE_LARGE | _PAGE_PRESENT;
pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_READ) << 4;
pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_WRITE) << 4;
pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_INVALID) << 5;
pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT);
pmd_val(pmd) |= (pte_val(pte) & _PAGE_DIRTY) << 10;
pmd_val(pmd) |= (pte_val(pte) & _PAGE_YOUNG) << 10;
} else
pte_val(pte) = _PAGE_INVALID;
return pte;
}
void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
pmd_t pmd;
pmd = __pte_to_pmd(pte);
if (!MACHINE_HAS_HPAGE) {
/* Emulated huge ptes loose the dirty and young bit */
pmd_val(pmd) &= ~_SEGMENT_ENTRY_ORIGIN;
pmd_val(pmd) |= pte_page(pte)[1].index;
} else
pmd_val(pmd) |= _SEGMENT_ENTRY_LARGE | _SEGMENT_ENTRY_CO;
*(pmd_t *) ptep = pmd;
}
pte_t huge_ptep_get(pte_t *ptep)
{
unsigned long origin;
pmd_t pmd;
pmd = *(pmd_t *) ptep;
if (!MACHINE_HAS_HPAGE && pmd_present(pmd)) {
origin = pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN;
pmd_val(pmd) &= ~_SEGMENT_ENTRY_ORIGIN;
pmd_val(pmd) |= *(unsigned long *) origin;
/* Emulated huge ptes are young and dirty by definition */
pmd_val(pmd) |= _SEGMENT_ENTRY_YOUNG | _SEGMENT_ENTRY_DIRTY;
}
return __pmd_to_pte(pmd);
}
pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
pmd_t *pmdp = (pmd_t *) ptep;
pte_t pte = huge_ptep_get(ptep);
pmdp_flush_direct(mm, addr, pmdp);
pmd_val(*pmdp) = _SEGMENT_ENTRY_EMPTY;
return pte;
}
int arch_prepare_hugepage(struct page *page)
{
unsigned long addr = page_to_phys(page);
pte_t pte;
pte_t *ptep;
int i;
if (MACHINE_HAS_HPAGE)
return 0;
ptep = (pte_t *) pte_alloc_one(&init_mm, addr);
if (!ptep)
return -ENOMEM;
pte_val(pte) = addr;
for (i = 0; i < PTRS_PER_PTE; i++) {
set_pte_at(&init_mm, addr + i * PAGE_SIZE, ptep + i, pte);
pte_val(pte) += PAGE_SIZE;
}
page[1].index = (unsigned long) ptep;
return 0;
}
void arch_release_hugepage(struct page *page)
{
pte_t *ptep;
if (MACHINE_HAS_HPAGE)
return;
ptep = (pte_t *) page[1].index;
if (!ptep)
return;
clear_table((unsigned long *) ptep, _PAGE_INVALID,
PTRS_PER_PTE * sizeof(pte_t));
page_table_free(&init_mm, (unsigned long *) ptep);
page[1].index = 0;
}
pte_t *huge_pte_alloc(struct mm_struct *mm,
unsigned long addr, unsigned long sz)
{
pgd_t *pgdp;
pud_t *pudp;
pmd_t *pmdp = NULL;
pgdp = pgd_offset(mm, addr);
pudp = pud_alloc(mm, pgdp, addr);
if (pudp)
pmdp = pmd_alloc(mm, pudp, addr);
return (pte_t *) pmdp;
}
pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
{
pgd_t *pgdp;
pud_t *pudp;
pmd_t *pmdp = NULL;
pgdp = pgd_offset(mm, addr);
if (pgd_present(*pgdp)) {
pudp = pud_offset(pgdp, addr);
if (pud_present(*pudp))
pmdp = pmd_offset(pudp, addr);
}
return (pte_t *) pmdp;
}
int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
return 0;
}
struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
int write)
{
return ERR_PTR(-EINVAL);
}
int pmd_huge(pmd_t pmd)
{
if (!MACHINE_HAS_HPAGE)
return 0;
return !!(pmd_val(pmd) & _SEGMENT_ENTRY_LARGE);
}
int pud_huge(pud_t pud)
{
return 0;
}
struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmdp, int write)
{
struct page *page;
if (!MACHINE_HAS_HPAGE)
return NULL;
page = pmd_page(*pmdp);
if (page)
page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
return page;
}
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