[PATCH] swsusp: fix swsusp with intel-agp

From: Pavel Machek <pavel@suse.cz>

swsusp contained rather nasty bug where it killed machine when intel-agp or
anything else split kernel 4MB mapping.  Herbert Xu diagnosed this.  Fixed by
switching to "known good" mapping for during suspend/resume.

arch/i386/mm/init.c

@@ -328,9 +328,30 @@ static void __init pagetable_init (void)
 #endif
 }
 
+#if defined(CONFIG_PM_DISK) || defined(CONFIG_SOFTWARE_SUSPEND)
+/*
+ * Swap suspend & friends need this for resume because things like the intel-agp
+ * driver might have split up a kernel 4MB mapping.
+ */
+char __nosavedata swsusp_pg_dir[PAGE_SIZE]
+	__attribute__ ((aligned (PAGE_SIZE)));
+
+static inline void save_pg_dir(void)
+{
+	memcpy(swsusp_pg_dir, swapper_pg_dir, PAGE_SIZE);
+}
+#else
+static inline void save_pg_dir(void)
+{
+}
+#endif
+
 void zap_low_mappings (void)
 {
 	int i;
+
+	save_pg_dir();
+
 	/*
 	 * Zap initial low-memory mappings.
 	 *

arch/i386/power/pmdisk.S

@@ -21,7 +21,7 @@ ENTRY(pmdisk_arch_suspend)
 	jmp .L1449
 	.p2align 4,,7
 .L1450:
-	movl $swapper_pg_dir-__PAGE_OFFSET,%ecx
+	movl $swsusp_pg_dir-__PAGE_OFFSET,%ecx
 	movl %ecx,%cr3
 
 	movl	pm_pagedir_nosave,%ebx

arch/i386/power/swsusp.S

@@ -36,7 +36,7 @@ ENTRY(do_magic)
 	jmp .L1449
 	.p2align 4,,7
 .L1450:
-	movl $swapper_pg_dir-__PAGE_OFFSET,%ecx
+	movl $swsusp_pg_dir-__PAGE_OFFSET,%ecx
 	movl %ecx,%cr3
 
 	call do_magic_resume_1