bitkeeper revision 1.1159.17.18 (411b7a4clSlwGNpVa4jPTa9wgDjfmw)

Add compile-time option to use writable pagetables.

linux-2.6.7-xen-sparse/arch/xen/Kconfig

@@ -36,6 +36,12 @@ config XEN_PHYSDEV_ACCESS
 	help
 	  Device-driver domain (physical device access)
 
+config XEN_WRITABLE_PAGETABLES
+	bool "Use writable pagetables"
+	default n
+	help
+	  Use writable L1 pagetables
+
 endmenu
 
 # Xen's block device backend driver needs 2^12 pages

linux-2.6.7-xen-sparse/arch/xen/i386/kernel/setup.c

@@ -1104,7 +1104,7 @@ void __init setup_arch(char **cmdline_p)
 
 	HYPERVISOR_vm_assist(VMASST_CMD_enable,
 			     VMASST_TYPE_4gb_segments);
-#if 0
+#ifdef CONFIG_XEN_WRITABLE_PAGETABLES
 	HYPERVISOR_vm_assist(VMASST_CMD_enable,
 			     VMASST_TYPE_writeable_pagetables);
 #endif

linux-2.6.7-xen-sparse/include/asm-xen/asm-i386/page.h

@@ -95,7 +95,7 @@ typedef struct { unsigned long pgprot; } pgprot_t;
 static inline unsigned long pmd_val(pmd_t x)
 {
     unsigned long ret = x.pmd;
-    if ( (ret & 1) ) ret = machine_to_phys(ret);
+    if ( (ret) ) ret = machine_to_phys(ret);
     return ret;
 }
 #define pgd_val(x)	({ BUG(); (unsigned long)0; })

linux-2.6.7-xen-sparse/include/asm-xen/asm-i386/pgalloc.h

@@ -6,6 +6,7 @@
 #include <asm/fixmap.h>
 #include <linux/threads.h>
 #include <linux/mm.h>		/* for struct page */
+#include <asm/io.h>		/* for phys_to_virt and page_to_pseudophys */
 
 #define pmd_populate_kernel(mm, pmd, pte) \
 		set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte)))
@@ -15,7 +16,8 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, struct page *p
 	set_pmd(pmd, __pmd(_PAGE_TABLE +
 		((unsigned long long)page_to_pfn(pte) <<
 			(unsigned long long) PAGE_SHIFT)));
-	flush_page_update_queue(); /* XXXcl flush */
+	flush_page_update_queue();
+	/* XXXcl queue */
 }
 /*
  * Allocate and free page tables.
@@ -30,17 +32,25 @@ extern struct page *pte_alloc_one(struct mm_struct *, unsigned long);
 static inline void pte_free_kernel(pte_t *pte)
 {
 	free_page((unsigned long)pte);
+	__make_page_writeable(pte);
 }
 
 static inline void pte_free(struct page *pte)
 {
-	__free_page(pte);
+#ifdef CONFIG_HIGHPTE
+	if (pte < highmem_start_page)
+#endif
+	{
+		__make_page_writeable(phys_to_virt(page_to_pseudophys(pte)));
+		__free_page(pte);
+	}
 }
 
 
 #define __pte_free_tlb(tlb,pte) do {			\
 	tlb_remove_page((tlb),(pte));			\
-	flush_page_update_queue(); /* XXXcl flush */	\
+	flush_page_update_queue();			\
+	/* XXXcl queue */ \
 } while (0)
 
 /*

linux-2.6.7-xen-sparse/include/asm-xen/asm-i386/pgtable-2level.h

@@ -40,8 +40,13 @@ static inline int pgd_present(pgd_t pgd)	{ return 1; }
  * within a page table are directly modified.  Thus, the following
  * hook is made available.
  */
+#ifdef CONFIG_XEN_WRITABLE_PAGETABLES
+#define set_pte(pteptr, pteval) (*(pteptr) = pteval)
+#define set_pte_atomic(pteptr, pteval) (*(pteptr) = pteval)
+#else
 #define set_pte(pteptr, pteval) queue_l1_entry_update(pteptr, (pteval).pte_low)
 #define set_pte_atomic(pteptr, pteval) queue_l1_entry_update(pteptr, (pteval).pte_low)
+#endif
 /*
  * (pmds are folded into pgds so this doesn't get actually called,
  * but the define is needed for a generic inline function.)
@@ -70,7 +75,7 @@ static inline pte_t ptep_get_and_clear(pte_t *xp)
 {
 	pte_t pte = *xp;
 	if (pte.pte_low)
-		queue_l1_entry_update(xp, 0);
+		set_pte(xp, __pte_ma(0));
 	return pte;
 }
 

linux-2.6.7-xen-sparse/include/asm-xen/asm-i386/pgtable.h

@@ -191,7 +191,7 @@ extern unsigned long pg0[];
 #define pmd_none(x)	(!pmd_val(x))
 #define pmd_present(x)	(pmd_val(x) & _PAGE_PRESENT)
 /* pmd_clear below */
-#define	pmd_bad(x)	((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE)
+#define	pmd_bad(x)	((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER & ~_PAGE_PRESENT)) != (_KERNPG_TABLE & ~_PAGE_PRESENT))
 
 
 #define pages_to_mb(x) ((x) >> (20-PAGE_SHIFT))
@@ -241,9 +241,9 @@ static inline  int ptep_test_and_clear_young(pte_t *ptep)
 }
 static inline void ptep_set_wrprotect(pte_t *ptep)
 {
-	unsigned long pteval = *(unsigned long *)ptep;
-	if ((pteval & _PAGE_RW))
-		queue_l1_entry_update(ptep, pteval & ~_PAGE_RW);
+	pte_t pte = *ptep;
+	if (pte_write(pte))
+		set_pte(ptep, pte_wrprotect(pte));
 }
 static inline void ptep_mkdirty(pte_t *ptep)
 {
@@ -283,6 +283,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 	pmd_t p = *(xp);					\
 	set_pmd(xp, __pmd(0));					\
 	__make_page_writeable((void *)pmd_page_kernel(p));	\
+	/* XXXcl queue */ \
 } while (0)
 
 #ifndef CONFIG_DISCONTIGMEM
@@ -401,6 +402,7 @@ static inline void make_page_readonly(void *va)
 	if ( (unsigned long)va >= VMALLOC_START )
 		__make_page_readonly(machine_to_virt(
 			*(unsigned long *)pte&PAGE_MASK));
+	/* XXXcl queue */
 }
 
 static inline void make_page_writeable(void *va)
@@ -412,6 +414,7 @@ static inline void make_page_writeable(void *va)
 	if ( (unsigned long)va >= VMALLOC_START )
 		__make_page_writeable(machine_to_virt(
 			*(unsigned long *)pte&PAGE_MASK));
+	/* XXXcl queue */
 }
 
 static inline void make_pages_readonly(void *va, unsigned int nr)
@@ -421,6 +424,7 @@ static inline void make_pages_readonly(void *va, unsigned int nr)
 		make_page_readonly(va);
 		va = (void *)((unsigned long)va + PAGE_SIZE);
 	}
+	/* XXXcl queue */
 }
 
 static inline void make_pages_writeable(void *va, unsigned int nr)
@@ -430,6 +434,7 @@ static inline void make_pages_writeable(void *va, unsigned int nr)
 		make_page_writeable(va);
 		va = (void *)((unsigned long)va + PAGE_SIZE);
 	}
+	/* XXXcl queue */
 }
 
 static inline unsigned long arbitrary_virt_to_phys(void *va)