diff options
Diffstat (limited to 'arch/powerpc/mm/pgtable.c')
| -rw-r--r-- | arch/powerpc/mm/pgtable.c | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index 6d94116fdea..a27ded3adac 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c @@ -1,5 +1,6 @@ /* * This file contains common routines for dealing with free of page tables + * Along with common page table handling code * * Derived from arch/powerpc/mm/tlb_64.c: * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) @@ -115,3 +116,133 @@ void pte_free_finish(void) pte_free_submit(*batchp); *batchp = NULL; } + +/* + * Handle i/d cache flushing, called from set_pte_at() or ptep_set_access_flags() + */ +static pte_t do_dcache_icache_coherency(pte_t pte) +{ + unsigned long pfn = pte_pfn(pte); + struct page *page; + + if (unlikely(!pfn_valid(pfn))) + return pte; + page = pfn_to_page(pfn); + + if (!PageReserved(page) && !test_bit(PG_arch_1, &page->flags)) { + pr_debug("do_dcache_icache_coherency... flushing\n"); + flush_dcache_icache_page(page); + set_bit(PG_arch_1, &page->flags); + } + else + pr_debug("do_dcache_icache_coherency... already clean\n"); + return __pte(pte_val(pte) | _PAGE_HWEXEC); +} + +static inline int is_exec_fault(void) +{ + return current->thread.regs && TRAP(current->thread.regs) == 0x400; +} + +/* We only try to do i/d cache coherency on stuff that looks like + * reasonably "normal" PTEs. We currently require a PTE to be present + * and we avoid _PAGE_SPECIAL and _PAGE_NO_CACHE + */ +static inline int pte_looks_normal(pte_t pte) +{ + return (pte_val(pte) & + (_PAGE_PRESENT | _PAGE_SPECIAL | _PAGE_NO_CACHE)) == + (_PAGE_PRESENT); +} + +#if defined(CONFIG_PPC_STD_MMU) +/* Server-style MMU handles coherency when hashing if HW exec permission + * is supposed per page (currently 64-bit only). Else, we always flush + * valid PTEs in set_pte. + */ +static inline int pte_need_exec_flush(pte_t pte, int set_pte) +{ + return set_pte && pte_looks_normal(pte) && + !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) || + cpu_has_feature(CPU_FTR_NOEXECUTE)); +} +#elif _PAGE_HWEXEC == 0 +/* Embedded type MMU without HW exec support (8xx only so far), we flush + * the cache for any present PTE + */ +static inline int pte_need_exec_flush(pte_t pte, int set_pte) +{ + return set_pte && pte_looks_normal(pte); +} +#else +/* Other embedded CPUs with HW exec support per-page, we flush on exec + * fault if HWEXEC is not set + */ +static inline int pte_need_exec_flush(pte_t pte, int set_pte) +{ + return pte_looks_normal(pte) && is_exec_fault() && + !(pte_val(pte) & _PAGE_HWEXEC); +} +#endif + +/* + * set_pte stores a linux PTE into the linux page table. + */ +void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte) +{ +#ifdef CONFIG_DEBUG_VM + WARN_ON(pte_present(*ptep)); +#endif + /* Note: mm->context.id might not yet have been assigned as + * this context might not have been activated yet when this + * is called. + */ + pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS); + if (pte_need_exec_flush(pte, 1)) + pte = do_dcache_icache_coherency(pte); + + /* Perform the setting of the PTE */ + __set_pte_at(mm, addr, ptep, pte, 0); +} + +/* + * This is called when relaxing access to a PTE. It's also called in the page + * fault path when we don't hit any of the major fault cases, ie, a minor + * update of _PAGE_ACCESSED, _PAGE_DIRTY, etc... The generic code will have + * handled those two for us, we additionally deal with missing execute + * permission here on some processors + */ +int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address, + pte_t *ptep, pte_t entry, int dirty) +{ + int changed; + if (!dirty && pte_need_exec_flush(entry, 0)) + entry = do_dcache_icache_coherency(entry); + changed = !pte_same(*(ptep), entry); + if (changed) { + assert_pte_locked(vma->vm_mm, address); + __ptep_set_access_flags(ptep, entry); + flush_tlb_page_nohash(vma, address); + } + return changed; +} + +#ifdef CONFIG_DEBUG_VM +void assert_pte_locked(struct mm_struct *mm, unsigned long addr) +{ + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + + if (mm == &init_mm) + return; + pgd = mm->pgd + pgd_index(addr); + BUG_ON(pgd_none(*pgd)); + pud = pud_offset(pgd, addr); + BUG_ON(pud_none(*pud)); + pmd = pmd_offset(pud, addr); + BUG_ON(!pmd_present(*pmd)); + BUG_ON(!spin_is_locked(pte_lockptr(mm, pmd))); +} +#endif /* CONFIG_DEBUG_VM */ + |