/* * Copyright 2002 Andi Kleen, SuSE Labs. * Thanks to Ben LaHaise for precious feedback. */ #include #include #include #include #include #include #include #include #include pte_t *lookup_address(unsigned long address, int *level) { pgd_t *pgd = pgd_offset_k(address); pud_t *pud; pmd_t *pmd; pte_t *pte; if (pgd_none(*pgd)) return NULL; pud = pud_offset(pgd, address); if (!pud_present(*pud)) return NULL; pmd = pmd_offset(pud, address); if (!pmd_present(*pmd)) return NULL; *level = 3; if (pmd_large(*pmd)) return (pte_t *)pmd; *level = 4; pte = pte_offset_kernel(pmd, address); if (pte && !pte_present(*pte)) pte = NULL; return pte; } static struct page * split_large_page(unsigned long address, pgprot_t prot, pgprot_t ref_prot) { unsigned long addr; struct page *base; pte_t *pbase; int i; base = alloc_pages(GFP_KERNEL, 0); if (!base) return NULL; /* * page_private is used to track the number of entries in * the page table page have non standard attributes. */ SetPagePrivate(base); page_private(base) = 0; address = __pa(address); addr = address & LARGE_PAGE_MASK; pbase = (pte_t *)page_address(base); for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) { pbase[i] = pfn_pte(addr >> PAGE_SHIFT, addr == address ? prot : ref_prot); } return base; } void clflush_cache_range(void *addr, int size) { int i; for (i = 0; i < size; i += boot_cpu_data.x86_clflush_size) clflush(addr+i); } static void flush_kernel_map(void *arg) { struct list_head *l = (struct list_head *)arg; struct page *pg; __flush_tlb_all(); /* When clflush is available always use it because it is much cheaper than WBINVD. */ /* clflush is still broken. Disable for now. */ if (1 || !cpu_has_clflush) { wbinvd(); } else { list_for_each_entry(pg, l, lru) { void *addr = page_address(pg); clflush_cache_range(addr, PAGE_SIZE); } } } static inline void flush_map(struct list_head *l) { on_each_cpu(flush_kernel_map, l, 1, 1); } static LIST_HEAD(deferred_pages); /* protected by init_mm.mmap_sem */ static inline void save_page(struct page *fpage) { if (!test_and_set_bit(PG_arch_1, &fpage->flags)) list_add(&fpage->lru, &deferred_pages); } /* * No more special protections in this 2/4MB area - revert to a * large page again. */ static void revert_page(unsigned long address, pgprot_t ref_prot) { unsigned long pfn; pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t large_pte; pgd = pgd_offset_k(address); BUG_ON(pgd_none(*pgd)); pud = pud_offset(pgd, address); BUG_ON(pud_none(*pud)); pmd = pmd_offset(pud, address); BUG_ON(pmd_val(*pmd) & _PAGE_PSE); pfn = (__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT; large_pte = pfn_pte(pfn, ref_prot); large_pte = pte_mkhuge(large_pte); set_pte((pte_t *)pmd, large_pte); } static int __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot, pgprot_t ref_prot) { struct page *kpte_page; pgprot_t ref_prot2; pte_t *kpte; int level; kpte = lookup_address(address, &level); if (!kpte) return 0; kpte_page = virt_to_page(kpte); BUG_ON(PageLRU(kpte_page)); BUG_ON(PageCompound(kpte_page)); if (pgprot_val(prot) != pgprot_val(ref_prot)) { if (level == 4) { set_pte(kpte, pfn_pte(pfn, prot)); } else { /* * split_large_page will take the reference for this * change_page_attr on the split page. */ struct page *split; ref_prot2 = pte_pgprot(pte_clrhuge(*kpte)); split = split_large_page(address, prot, ref_prot2); if (!split) return -ENOMEM; pgprot_val(ref_prot2) &= ~_PAGE_NX; set_pte(kpte, mk_pte(split, ref_prot2)); kpte_page = split; } page_private(kpte_page)++; } else { if (level == 4) { set_pte(kpte, pfn_pte(pfn, ref_prot)); BUG_ON(page_private(kpte_page) == 0); page_private(kpte_page)--; } else BUG(); } /* on x86-64 the direct mapping set at boot is not using 4k pages */ BUG_ON(PageReserved(kpte_page)); save_page(kpte_page); if (page_private(kpte_page) == 0) revert_page(address, ref_prot); return 0; } /* * Change the page attributes of an page in the linear mapping. * * This should be used when a page is mapped with a different caching policy * than write-back somewhere - some CPUs do not like it when mappings with * different caching policies exist. This changes the page attributes of the * in kernel linear mapping too. * * The caller needs to ensure that there are no conflicting mappings elsewhere. * This function only deals with the kernel linear map. * * Caller must call global_flush_tlb() after this. */ int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot) { int err = 0, kernel_map = 0, i; if (address >= __START_KERNEL_map && address < __START_KERNEL_map + KERNEL_TEXT_SIZE) { address = (unsigned long)__va(__pa(address)); kernel_map = 1; } down_write(&init_mm.mmap_sem); for (i = 0; i < numpages; i++, address += PAGE_SIZE) { unsigned long pfn = __pa(address) >> PAGE_SHIFT; if (!kernel_map || pte_present(pfn_pte(0, prot))) { err = __change_page_attr(address, pfn, prot, PAGE_KERNEL); if (err) break; } /* Handle kernel mapping too which aliases part of the * lowmem */ if (__pa(address) < KERNEL_TEXT_SIZE) { unsigned long addr2; pgprot_t prot2; addr2 = __START_KERNEL_map + __pa(address); /* Make sure the kernel mappings stay executable */ prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot))); err = __change_page_attr(addr2, pfn, prot2, PAGE_KERNEL_EXEC); } } up_write(&init_mm.mmap_sem); return err; } /* Don't call this for MMIO areas that may not have a mem_map entry */ int change_page_attr(struct page *page, int numpages, pgprot_t prot) { unsigned long addr = (unsigned long)page_address(page); return change_page_attr_addr(addr, numpages, prot); } EXPORT_SYMBOL(change_page_attr); void global_flush_tlb(void) { struct page *pg, *next; struct list_head l; /* * Write-protect the semaphore, to exclude two contexts * doing a list_replace_init() call in parallel and to * exclude new additions to the deferred_pages list: */ down_write(&init_mm.mmap_sem); list_replace_init(&deferred_pages, &l); up_write(&init_mm.mmap_sem); flush_map(&l); list_for_each_entry_safe(pg, next, &l, lru) { list_del(&pg->lru); clear_bit(PG_arch_1, &pg->flags); if (page_private(pg) != 0) continue; ClearPagePrivate(pg); __free_page(pg); } } EXPORT_SYMBOL(global_flush_tlb);