simplified macros

arch/x86/include/asm/page.h

@@ -68,11 +68,29 @@
 /// The number of entries in a page map table
 #define PAGE_MAP_ENTRIES	(1L << PAGE_MAP_BITS)
 
+// Base addresses of the self-mapped pagetables
+#ifdef CONFIG_X86_32
+ #define PAGE_MAP_PGD		0xFFFFF000
+ #define PAGE_MAP_PGT		0xFFC00000
+#elif defined(CONFIG_X86_64)
+ #define PAGE_MAP_PML4		0xFFFFFFFFFFFFF000
+ #define PAGE_MAP_PDPT		0xFFFFFFFFFFE00000
+ #define PAGE_MAP_PGD		0xFFFFFFFFC0000000
+ #define PAGE_MAP_PGT		0xFFFFFF8000000000
+#endif
+
 /// Align to next page
 #define PAGE_FLOOR(addr)	(((addr) + PAGE_SIZE - 1) & PAGE_MASK)
 /// Align to page
 #define PAGE_CEIL(addr)		( (addr)                  & PAGE_MASK)
 
+// Canonical address format
+#ifdef CONFIG_x86_32
+ #define CANONICAL(addr)	(addr)
+#elif defined(CONFIG_X86_64)
+ #define CANONICAL(addr)	sign_extend(addr, VIRT_BITS)
+#endif
+
 /// Page is present
 #define PG_PRESENT		(1 << 0)
 /// Page is read- and writable

arch/x86/include/asm/page_helpers.h

@@ -37,36 +37,38 @@
  */
 static inline size_t sign_extend(ssize_t addr, int bits)
 {
-	return (addr << -bits) >> -bits; // sign bit is maintained during arithmetic right shift
+	int shift = BITS - bits;
+	return (addr << shift) >> shift; // sign bit gets copied during arithmetic right shift
 }
 
-/** @brief */
+/** @brief Get the base address of the child table
+ *
+ * @param entry The parent entry
+ * @return The child entry
+ */
 static inline page_entry_t* get_child_entry(page_entry_t *entry)
 {
 	size_t child = (size_t) entry;
 
 	child <<= PAGE_MAP_BITS;
 
-#ifdef CONFIG_X86_32
+	return (page_entry_t*) CANONICAL(child);
-	return (page_entry_t*) child;
-#elif defined(CONFIG_X86_64)
-	return (page_entry_t*) sign_extend(child, VIRT_BITS);
-#endif
 }
 
-/** @brief */
+/** @brief Get the base address of the parent entry
+ *
+ * @param entry The child entry
+ * @return The parent entry
+ */
 static inline page_entry_t* get_parent_entry(page_entry_t *entry)
 {
-	size_t parent = (size_t) entry;
+	ssize_t parent = (size_t) entry;
 
 	parent >>= PAGE_MAP_BITS;
-	parent |= (PAGE_MAP_ENTRIES-1) << (PAGE_MAP_LEVELS * PAGE_MAP_BITS + 3); // TODO
+	parent |= PAGE_MAP_PGT;
+	parent &= ~(sizeof(size_t) - 1); // align to page_entry_t
 
-#ifdef CONFIG_X86_32
+	return (page_entry_t*) CANONICAL(parent);
-	return (page_entry_t*) (parent & ~0x3);
-#elif defined(CONFIG_X86_64)
-	return (page_entry_t*) sign_extend(parent & ~0x7, VIRT_BITS);
-#endif
 }
 
 /** @brief Get the corresponding page map entry to a given virtual address
@@ -74,18 +76,15 @@ static inline page_entry_t* get_parent_entry(page_entry_t *entry)
  * Please note: this implementation requires that the tables are mapped
  * at the end of VAS!
  */
-static inline page_entry_t* virt_to_entry(size_t addr, int level)
+static inline page_entry_t* virt_to_entry(ssize_t addr, int level)
 {
-	do {
 	addr >>= PAGE_MAP_BITS;
-		addr |= (PAGE_MAP_ENTRIES-1) << (PAGE_MAP_LEVELS * PAGE_MAP_BITS + 3); // TODO
+	addr |= PAGE_MAP_PGT;
-	} while (level--);
 
-#ifdef CONFIG_X86_32
+	addr >>= level * PAGE_MAP_BITS;
-	return (page_entry_t*) (addr & ~0x3);
+ 	addr &= ~(sizeof(size_t) - 1); // align to page_entry_t
-#elif defined(CONFIG_X86_64)
+
-	return (page_entry_t*) sign_extend(addr & ~0x7, VIRT_BITS);
+	return (page_entry_t*) CANONICAL(addr);
-#endif
 }
 
 /** @brief Get the corresponding virtual address to a page map entry */
@@ -95,11 +94,7 @@ static inline size_t entry_to_virt(page_entry_t* entry, int level)
 
 	addr <<= (level+1) * PAGE_MAP_BITS;
 
-#ifdef CONFIG_X86_32
+	return CANONICAL(addr);
-	return addr;
-#elif defined(CONFIG_X86_64)
-	return sign_extend(addr, VIRT_BITS); // sign extend
-#endif
 }
 
 /** @brief Converts a virtual address to a physical
@@ -150,6 +145,7 @@ size_t get_page_flags(size_t viraddr)
 	int i;
 	for (i=1; i<PAGE_MAP_LEVELS; i++) {
 		entry = virt_to_entry(viraddr, i);
+
 #ifdef CONFIG_X86_64
 		flags |= (*entry & PG_XD);
 #endif

arch/x86/mm/page64.c

@@ -59,9 +59,9 @@ extern page_entry_t boot_pml4[PAGE_MAP_ENTRIES];
 static spinlock_t kslock = SPINLOCK_INIT;
 
 /// Mapping of self referenced page map (at the end of the VAS)
-static page_entry_t* const current_map = (page_entry_t*) (-1*PAGE_SIZE);
+static page_entry_t* const current_map = (page_entry_t*) (1 * PAGE_MAP_PML4);
-static page_entry_t* const src_map =     (page_entry_t*) (-2*PAGE_SIZE);
+static page_entry_t* const src_map =     (page_entry_t*) (2 * PAGE_MAP_PML4);
-static page_entry_t* const dest_map =    (page_entry_t*) (-3*PAGE_SIZE);
+static page_entry_t* const dest_map =    (page_entry_t*) (3 * PAGE_MAP_PML4);
 
 page_entry_t* get_boot_page_map(void)
 {
@@ -159,10 +159,12 @@ void page_stats(int reset)
 						if (*entry & (1 << i))
 							stats[i]++;
 					}
+#ifdef CONFIG_X86_64
 					for (i=0; i<1; i++) {	// IA-32e / PAE bits
 						if (*entry & (1 << (63-i)))
 							stats[i+PAGE_BITS]++;
 					}
+#endif
 
 					if (reset) { // reset accessed and dirty bits
 						*entry &= ~(PG_ACCESSED|PG_DIRTY);