--- /dev/null
+/*
+ * Copyright 2002 Andi Kleen, SuSE Labs.
+ * Thanks to Ben LaHaise for precious feedback.
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <asm/uaccess.h>
+#include <asm/processor.h>
+#include <asm/tlbflush.h>
+#include <asm/io.h>
+
+#ifdef CONFIG_XEN
+#include <asm/pgalloc.h>
+#include <asm/mmu_context.h>
+
+LIST_HEAD(mm_unpinned);
+DEFINE_SPINLOCK(mm_unpinned_lock);
+
+static inline void mm_walk_set_prot(void *pt, pgprot_t flags)
+{
+ struct page *page = virt_to_page(pt);
+ unsigned long pfn = page_to_pfn(page);
+
+ BUG_ON(HYPERVISOR_update_va_mapping(
+ (unsigned long)__va(pfn << PAGE_SHIFT),
+ pfn_pte(pfn, flags), 0));
+}
+
+static void mm_walk(struct mm_struct *mm, pgprot_t flags)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+ int g,u,m;
+
+ pgd = mm->pgd;
+ /*
+ * Cannot iterate up to USER_PTRS_PER_PGD as these pagetables may not
+ * be the 'current' task's pagetables (e.g., current may be 32-bit,
+ * but the pagetables may be for a 64-bit task).
+ * Subtracting 1 from TASK_SIZE64 means the loop limit is correct
+ * regardless of whether TASK_SIZE64 is a multiple of PGDIR_SIZE.
+ */
+ for (g = 0; g <= ((TASK_SIZE64-1) / PGDIR_SIZE); g++, pgd++) {
+ if (pgd_none(*pgd))
+ continue;
+ pud = pud_offset(pgd, 0);
+ if (PTRS_PER_PUD > 1) /* not folded */
+ mm_walk_set_prot(pud,flags);
+ for (u = 0; u < PTRS_PER_PUD; u++, pud++) {
+ if (pud_none(*pud))
+ continue;
+ pmd = pmd_offset(pud, 0);
+ if (PTRS_PER_PMD > 1) /* not folded */
+ mm_walk_set_prot(pmd,flags);
+ for (m = 0; m < PTRS_PER_PMD; m++, pmd++) {
+ if (pmd_none(*pmd))
+ continue;
+ pte = pte_offset_kernel(pmd,0);
+ mm_walk_set_prot(pte,flags);
+ }
+ }
+ }
+}
+
+void mm_pin(struct mm_struct *mm)
+{
+ if (xen_feature(XENFEAT_writable_page_tables))
+ return;
+
+ spin_lock(&mm->page_table_lock);
+
+ mm_walk(mm, PAGE_KERNEL_RO);
+ BUG_ON(HYPERVISOR_update_va_mapping(
+ (unsigned long)mm->pgd,
+ pfn_pte(virt_to_phys(mm->pgd)>>PAGE_SHIFT, PAGE_KERNEL_RO),
+ UVMF_TLB_FLUSH));
+ BUG_ON(HYPERVISOR_update_va_mapping(
+ (unsigned long)__user_pgd(mm->pgd),
+ pfn_pte(virt_to_phys(__user_pgd(mm->pgd))>>PAGE_SHIFT, PAGE_KERNEL_RO),
+ UVMF_TLB_FLUSH));
+ xen_pgd_pin(__pa(mm->pgd)); /* kernel */
+ xen_pgd_pin(__pa(__user_pgd(mm->pgd))); /* user */
+ mm->context.pinned = 1;
+ spin_lock(&mm_unpinned_lock);
+ list_del(&mm->context.unpinned);
+ spin_unlock(&mm_unpinned_lock);
+
+ spin_unlock(&mm->page_table_lock);
+}
+
+void mm_unpin(struct mm_struct *mm)
+{
+ if (xen_feature(XENFEAT_writable_page_tables))
+ return;
+
+ spin_lock(&mm->page_table_lock);
+
+ xen_pgd_unpin(__pa(mm->pgd));
+ xen_pgd_unpin(__pa(__user_pgd(mm->pgd)));
+ BUG_ON(HYPERVISOR_update_va_mapping(
+ (unsigned long)mm->pgd,
+ pfn_pte(virt_to_phys(mm->pgd)>>PAGE_SHIFT, PAGE_KERNEL), 0));
+ BUG_ON(HYPERVISOR_update_va_mapping(
+ (unsigned long)__user_pgd(mm->pgd),
+ pfn_pte(virt_to_phys(__user_pgd(mm->pgd))>>PAGE_SHIFT, PAGE_KERNEL), 0));
+ mm_walk(mm, PAGE_KERNEL);
+ xen_tlb_flush();
+ mm->context.pinned = 0;
+ spin_lock(&mm_unpinned_lock);
+ list_add(&mm->context.unpinned, &mm_unpinned);
+ spin_unlock(&mm_unpinned_lock);
+
+ spin_unlock(&mm->page_table_lock);
+}
+
+void mm_pin_all(void)
+{
+ if (xen_feature(XENFEAT_writable_page_tables))
+ return;
+
+ while (!list_empty(&mm_unpinned))
+ mm_pin(list_entry(mm_unpinned.next, struct mm_struct,
+ context.unpinned));
+}
+
+void _arch_dup_mmap(struct mm_struct *mm)
+{
+ if (!mm->context.pinned)
+ mm_pin(mm);
+}
+
+void _arch_exit_mmap(struct mm_struct *mm)
+{
+ struct task_struct *tsk = current;
+
+ task_lock(tsk);
+
+ /*
+ * We aggressively remove defunct pgd from cr3. We execute unmap_vmas()
+ * *much* faster this way, as no tlb flushes means bigger wrpt batches.
+ */
+ if ( tsk->active_mm == mm )
+ {
+ tsk->active_mm = &init_mm;
+ atomic_inc(&init_mm.mm_count);
+
+ switch_mm(mm, &init_mm, tsk);
+
+ atomic_dec(&mm->mm_count);
+ BUG_ON(atomic_read(&mm->mm_count) == 0);
+ }
+
+ task_unlock(tsk);
+
+ if ( mm->context.pinned && (atomic_read(&mm->mm_count) == 1) &&
+ !mm->context.has_foreign_mappings )
+ mm_unpin(mm);
+}
+
+void pte_free(struct page *pte)
+{
+ unsigned long va = (unsigned long)__va(page_to_pfn(pte)<<PAGE_SHIFT);
+
+ if (!pte_write(*virt_to_ptep(va)))
+ BUG_ON(HYPERVISOR_update_va_mapping(
+ va, pfn_pte(page_to_pfn(pte), PAGE_KERNEL), 0));
+ __free_page(pte);
+}
+#endif /* CONFIG_XEN */
+
+static inline pte_t *lookup_address(unsigned long address)
+{
+ 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;
+ if (pmd_large(*pmd))
+ return (pte_t *)pmd;
+ 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)
+{
+ int i;
+ unsigned long addr;
+ struct page *base = alloc_pages(GFP_KERNEL, 0);
+ pte_t *pbase;
+ 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;
+}
+
+
+static void flush_kernel_map(void *address)
+{
+ if (0 && address && cpu_has_clflush) {
+ /* is this worth it? */
+ int i;
+ for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size)
+ asm volatile("clflush (%0)" :: "r" (address + i));
+ } else
+ asm volatile("wbinvd":::"memory");
+ if (address)
+ __flush_tlb_one(address);
+ else
+ __flush_tlb_all();
+}
+
+
+static inline void flush_map(unsigned long address)
+{
+ on_each_cpu(flush_kernel_map, (void *)address, 1, 1);
+}
+
+static struct page *deferred_pages; /* protected by init_mm.mmap_sem */
+
+static inline void save_page(struct page *fpage)
+{
+ fpage->lru.next = (struct list_head *)deferred_pages;
+ deferred_pages = fpage;
+}
+
+/*
+ * 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)
+{
+ 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);
+ pgprot_val(ref_prot) |= _PAGE_PSE;
+ large_pte = mk_pte_phys(__pa(address) & LARGE_PAGE_MASK, ref_prot);
+ 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)
+{
+ pte_t *kpte;
+ struct page *kpte_page;
+ unsigned kpte_flags;
+ pgprot_t ref_prot2;
+ kpte = lookup_address(address);
+ if (!kpte) return 0;
+ kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
+ kpte_flags = pte_val(*kpte);
+ if (pgprot_val(prot) != pgprot_val(ref_prot)) {
+ if ((kpte_flags & _PAGE_PSE) == 0) {
+ 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 = __pgprot(pgprot_val(pte_pgprot(*lookup_address(address))) & ~(1<<_PAGE_BIT_PSE));
+
+ split = split_large_page(address, prot, ref_prot2);
+ if (!split)
+ return -ENOMEM;
+ set_pte(kpte,mk_pte(split, ref_prot2));
+ kpte_page = split;
+ }
+ page_private(kpte_page)++;
+ } else if ((kpte_flags & _PAGE_PSE) == 0) {
+ 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 */
+ /*
+ * ..., but the XEN guest kernels (currently) do:
+ * If the pte was reserved, it means it was created at boot
+ * time (not via split_large_page) and in turn we must not
+ * replace it with a large page.
+ */
+#ifndef CONFIG_XEN
+ BUG_ON(PageReserved(kpte_page));
+#endif
+ if (page_private(kpte_page) == 0) {
+ save_page(kpte_page);
+ 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;
+ int i;
+
+ down_write(&init_mm.mmap_sem);
+ for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
+ unsigned long pfn = __pa(address) >> PAGE_SHIFT;
+
+ 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 = prot;
+ addr2 = __START_KERNEL_map + __pa(address);
+ pgprot_val(prot2) &= ~_PAGE_NX;
+ 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);
+}
+
+void global_flush_tlb(void)
+{
+ struct page *dpage;
+
+ down_read(&init_mm.mmap_sem);
+ dpage = xchg(&deferred_pages, NULL);
+ up_read(&init_mm.mmap_sem);
+
+ flush_map((dpage && !dpage->lru.next) ? (unsigned long)page_address(dpage) : 0);
+ while (dpage) {
+ struct page *tmp = dpage;
+ dpage = (struct page *)dpage->lru.next;
+ ClearPagePrivate(tmp);
+ __free_page(tmp);
+ }
+}
+
+EXPORT_SYMBOL(change_page_attr);
+EXPORT_SYMBOL(global_flush_tlb);
git://git.onelab.eu / linux-2.6.git / blobdiff