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hugetlb.h

/*
 *  IBM System z Huge TLB Page Support for Kernel.
 *
 *    Copyright IBM Corp. 2008
 *    Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
 */

#ifndef _ASM_S390_HUGETLB_H
#define _ASM_S390_HUGETLB_H

#include <asm/page.h>
#include <asm/pgtable.h>


#define is_hugepage_only_range(mm, addr, len)   0
#define hugetlb_free_pgd_range                  free_pgd_range

void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
                 pte_t *ptep, pte_t pte);

/*
 * If the arch doesn't supply something else, assume that hugepage
 * size aligned regions are ok without further preparation.
 */
static inline int prepare_hugepage_range(struct file *file,
                  unsigned long addr, unsigned long len)
{
      if (len & ~HPAGE_MASK)
            return -EINVAL;
      if (addr & ~HPAGE_MASK)
            return -EINVAL;
      return 0;
}

#define hugetlb_prefault_arch_hook(mm)          do { } while (0)

int arch_prepare_hugepage(struct page *page);
void arch_release_hugepage(struct page *page);

static inline pte_t pte_mkhuge(pte_t pte)
{
      /*
       * PROT_NONE needs to be remapped from the pte type to the ste type.
       * The HW invalid bit is also different for pte and ste. The pte
       * invalid bit happens to be the same as the ste _SEGMENT_ENTRY_LARGE
       * bit, so we don't have to clear it.
       */
      if (pte_val(pte) & _PAGE_INVALID) {
            if (pte_val(pte) & _PAGE_SWT)
                  pte_val(pte) |= _HPAGE_TYPE_NONE;
            pte_val(pte) |= _SEGMENT_ENTRY_INV;
      }
      /*
       * Clear SW pte bits SWT and SWX, there are no SW bits in a segment
       * table entry.
       */
      pte_val(pte) &= ~(_PAGE_SWT | _PAGE_SWX);
      /*
       * Also set the change-override bit because we don't need dirty bit
       * tracking for hugetlbfs pages.
       */
      pte_val(pte) |= (_SEGMENT_ENTRY_LARGE | _SEGMENT_ENTRY_CO);
      return pte;
}

static inline pte_t huge_pte_wrprotect(pte_t pte)
{
      pte_val(pte) |= _PAGE_RO;
      return pte;
}

static inline int huge_pte_none(pte_t pte)
{
      return (pte_val(pte) & _SEGMENT_ENTRY_INV) &&
            !(pte_val(pte) & _SEGMENT_ENTRY_RO);
}

static inline pte_t huge_ptep_get(pte_t *ptep)
{
      pte_t pte = *ptep;
      unsigned long mask;

      if (!MACHINE_HAS_HPAGE) {
            ptep = (pte_t *) (pte_val(pte) & _SEGMENT_ENTRY_ORIGIN);
            if (ptep) {
                  mask = pte_val(pte) &
                        (_SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO);
                  pte = pte_mkhuge(*ptep);
                  pte_val(pte) |= mask;
            }
      }
      return pte;
}

static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
                                  unsigned long addr, pte_t *ptep)
{
      pte_t pte = huge_ptep_get(ptep);

      pmd_clear((pmd_t *) ptep);
      return pte;
}

static inline void __pmd_csp(pmd_t *pmdp)
{
      register unsigned long reg2 asm("2") = pmd_val(*pmdp);
      register unsigned long reg3 asm("3") = pmd_val(*pmdp) |
                                     _SEGMENT_ENTRY_INV;
      register unsigned long reg4 asm("4") = ((unsigned long) pmdp) + 5;

      asm volatile(
            "     csp %1,%3"
            : "=m" (*pmdp)
            : "d" (reg2), "d" (reg3), "d" (reg4), "m" (*pmdp) : "cc");
      pmd_val(*pmdp) = _SEGMENT_ENTRY_INV | _SEGMENT_ENTRY;
}

static inline void __pmd_idte(unsigned long address, pmd_t *pmdp)
{
      unsigned long sto = (unsigned long) pmdp -
                        pmd_index(address) * sizeof(pmd_t);

      if (!(pmd_val(*pmdp) & _SEGMENT_ENTRY_INV)) {
            asm volatile(
                  "     .insn rrf,0xb98e0000,%2,%3,0,0"
                  : "=m" (*pmdp)
                  : "m" (*pmdp), "a" (sto),
                    "a" ((address & HPAGE_MASK))
            );
      }
      pmd_val(*pmdp) = _SEGMENT_ENTRY_INV | _SEGMENT_ENTRY;
}

static inline void huge_ptep_invalidate(struct mm_struct *mm,
                              unsigned long address, pte_t *ptep)
{
      pmd_t *pmdp = (pmd_t *) ptep;

      if (!MACHINE_HAS_IDTE) {
            __pmd_csp(pmdp);
            if (mm->context.noexec) {
                  pmdp = get_shadow_table(pmdp);
                  __pmd_csp(pmdp);
            }
            return;
      }

      __pmd_idte(address, pmdp);
      if (mm->context.noexec) {
            pmdp = get_shadow_table(pmdp);
            __pmd_idte(address, pmdp);
      }
      return;
}

#define huge_ptep_set_access_flags(__vma, __addr, __ptep, __entry, __dirty) \
({                                                        \
      int __changed = !pte_same(huge_ptep_get(__ptep), __entry);      \
      if (__changed) {                                    \
            huge_ptep_invalidate((__vma)->vm_mm, __addr, __ptep);     \
            set_huge_pte_at((__vma)->vm_mm, __addr, __ptep, __entry);   \
      }                                                   \
      __changed;                                          \
})

#define huge_ptep_set_wrprotect(__mm, __addr, __ptep)             \
({                                                    \
      pte_t __pte = huge_ptep_get(__ptep);                        \
      if (pte_write(__pte)) {                               \
            if (atomic_read(&(__mm)->mm_users) > 1 ||       \
                (__mm) != current->active_mm)               \
                  huge_ptep_invalidate(__mm, __addr, __ptep);     \
            set_huge_pte_at(__mm, __addr, __ptep,                 \
                        huge_pte_wrprotect(__pte));         \
      }                                               \
})

static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
                               unsigned long address, pte_t *ptep)
{
      huge_ptep_invalidate(vma->vm_mm, address, ptep);
}

#endif /* _ASM_S390_HUGETLB_H */

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