X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fx86_64%2Fmm%2Fpageattr.c;h=f038f1def0187b5a8039e7f3cfd5a270e3b713b3;hb=refs%2Fheads%2Fvserver;hp=35f1f1aab0638ac41699ec718980c26fd40b383d;hpb=76828883507a47dae78837ab5dec5a5b4513c667;p=linux-2.6.git

diff --git a/arch/x86_64/mm/pageattr.c b/arch/x86_64/mm/pageattr.c
index 35f1f1aab..f038f1def 100644
--- a/arch/x86_64/mm/pageattr.c
+++ b/arch/x86_64/mm/pageattr.c
@@ -3,7 +3,6 @@
  * Thanks to Ben LaHaise for precious feedback.
  */ 
 
-#include <linux/config.h>
 #include <linux/mm.h>
 #include <linux/sched.h>
 #include <linux/highmem.h>
@@ -14,6 +13,167 @@
 #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);
@@ -45,6 +205,13 @@ static struct page *split_large_page(unsigned long address, pgprot_t prot,
 	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);
@@ -55,48 +222,40 @@ static struct page *split_large_page(unsigned long address, pgprot_t prot,
 	return base;
 } 
 
-
-static void flush_kernel_map(void *address) 
+static void cache_flush_page(void *adr)
 {
-	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();
+	int i;
+	for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size)
+		asm volatile("clflush (%0)" :: "r" (adr + i));
 }
 
+static void flush_kernel_map(void *arg)
+{
+	struct list_head *l = (struct list_head *)arg;
+	struct page *pg;
 
-static inline void flush_map(unsigned long address)
+	/* When clflush is available always use it because it is
+	   much cheaper than WBINVD */
+	if (!cpu_has_clflush)
+		asm volatile("wbinvd" ::: "memory");
+	list_for_each_entry(pg, l, lru) {
+		void *adr = page_address(pg);
+		if (cpu_has_clflush)
+			cache_flush_page(adr);
+	}
+	__flush_tlb_all();
+}
+
+static inline void flush_map(struct list_head *l)
 {	
-	on_each_cpu(flush_kernel_map, (void *)address, 1, 1);
+	on_each_cpu(flush_kernel_map, l, 1, 1);
 }
 
-struct deferred_page { 
-	struct deferred_page *next; 
-	struct page *fpage;
-	unsigned long address;
-}; 
-static struct deferred_page *df_list; /* protected by init_mm.mmap_sem */
+static LIST_HEAD(deferred_pages); /* protected by init_mm.mmap_sem */
 
-static inline void save_page(unsigned long address, struct page *fpage)
+static inline void save_page(struct page *fpage)
 {
-	struct deferred_page *df;
-	df = kmalloc(sizeof(struct deferred_page), GFP_KERNEL); 
-	if (!df) {
-		flush_map(address);
-		__free_page(fpage);
-	} else { 
-		df->next = df_list;
-		df->fpage = fpage;
-		df->address = address;
-		df_list = df;
-	} 			
+	list_add(&fpage->lru, &deferred_pages);
 }
 
 /* 
@@ -116,8 +275,8 @@ static void revert_page(unsigned long address, pgprot_t ref_prot)
 	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);
+	large_pte = pte_mkhuge(large_pte);
 	set_pte((pte_t *)pmd, large_pte);
 }      
 
@@ -127,47 +286,50 @@ __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t 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) { 
+		if (!pte_huge(*kpte)) {
 			set_pte(kpte, pfn_pte(pfn, prot));
 		} else {
  			/*
- 			 * split_large_page will take the reference for this change_page_attr
- 			 * on the split page.
+			 * 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));
-
+			ref_prot2 = pte_pgprot(pte_clrhuge(*kpte));
 			split = split_large_page(address, prot, ref_prot2);
 			if (!split)
 				return -ENOMEM;
-			set_pte(kpte,mk_pte(split, ref_prot2));
+			set_pte(kpte, mk_pte(split, ref_prot2));
 			kpte_page = split;
-		}	
-		get_page(kpte_page);
-	} else if ((kpte_flags & _PAGE_PSE) == 0) { 
+		}
+		page_private(kpte_page)++;
+	} else if (!pte_huge(*kpte)) {
 		set_pte(kpte, pfn_pte(pfn, ref_prot));
-		__put_page(kpte_page);
+		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));
+#else
+	if(!PageReserved(kpte_page))
+#endif
 
-	switch (page_count(kpte_page)) {
- 	case 1:
-		save_page(address, kpte_page); 		     
+	if (page_private(kpte_page) == 0) {
+		save_page(kpte_page);
 		revert_page(address, ref_prot);
-		break;
- 	case 0:
- 		BUG(); /* memleak and failed 2M page regeneration */
  	}
 	return 0;
 } 
@@ -201,10 +363,12 @@ int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
 		 * lowmem */
 		if (__pa(address) < KERNEL_TEXT_SIZE) {
 			unsigned long addr2;
-			pgprot_t prot2 = prot;
+			pgprot_t prot2;
 			addr2 = __START_KERNEL_map + __pa(address);
- 			pgprot_val(prot2) &= ~_PAGE_NX;
-			err = __change_page_attr(addr2, pfn, prot2, PAGE_KERNEL_EXEC);
+			/* 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); 
@@ -220,17 +384,18 @@ int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 
 void global_flush_tlb(void)
 { 
-	struct deferred_page *df, *next_df;
+	struct page *pg, *next;
+	struct list_head l;
 
 	down_read(&init_mm.mmap_sem);
-	df = xchg(&df_list, NULL);
+	list_replace_init(&deferred_pages, &l);
 	up_read(&init_mm.mmap_sem);
-	flush_map((df && !df->next) ? df->address : 0);
-	for (; df; df = next_df) { 
-		next_df = df->next;
-		if (df->fpage) 
-			__free_page(df->fpage);
-		kfree(df);
+
+	flush_map(&l);
+
+	list_for_each_entry_safe(pg, next, &l, lru) {
+		ClearPagePrivate(pg);
+		__free_page(pg);
 	} 
 }