i386: do not restore reserved memory after hibernation

On some systems the ACPI NVS area is located in the first 1 MB of RAM and
it is overwritten by the i386 code during the restore after hibernation.
This confuses the ACPI platform firmware that doesn't update the AC adapter
status appropriately as a result
(http://bugzilla.kernel.org/show_bug.cgi?id=7995).

The solution is to register the reserved memory in the first 1 MB as
'nosave', so that swsusp doesn't touch it during the restore.  Also, this
has been done on x86_64 for a long time now, so this patch makes the i386
restore code behave like the x86_64 one.

[akpm@linux-foundation.org: build fix]
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/i386/kernel/e820.c

@@ -10,6 +10,7 @@
 #include <linux/efi.h>
 #include <linux/pfn.h>
 #include <linux/uaccess.h>
+#include <linux/suspend.h>
 
 #include <asm/pgtable.h>
 #include <asm/page.h>
@@ -320,6 +321,37 @@ static int __init request_standard_resources(void)
 
 subsys_initcall(request_standard_resources);
 
+#if defined(CONFIG_PM) && defined(CONFIG_SOFTWARE_SUSPEND)
+/**
+ * e820_mark_nosave_regions - Find the ranges of physical addresses that do not
+ * correspond to e820 RAM areas and mark the corresponding pages as nosave for
+ * hibernation.
+ *
+ * This function requires the e820 map to be sorted and without any
+ * overlapping entries and assumes the first e820 area to be RAM.
+ */
+void __init e820_mark_nosave_regions(void)
+{
+	int i;
+	unsigned long pfn;
+
+	pfn = PFN_DOWN(e820.map[0].addr + e820.map[0].size);
+	for (i = 1; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i];
+
+		if (pfn < PFN_UP(ei->addr))
+			register_nosave_region(pfn, PFN_UP(ei->addr));
+
+		pfn = PFN_DOWN(ei->addr + ei->size);
+		if (ei->type != E820_RAM)
+			register_nosave_region(PFN_UP(ei->addr), pfn);
+
+		if (pfn >= max_low_pfn)
+			break;
+	}
+}
+#endif
+
 void __init add_memory_region(unsigned long long start,
 			      unsigned long long size, int type)
 {

arch/i386/kernel/setup.c

@@ -640,6 +640,7 @@ void __init setup_arch(char **cmdline_p)
 #endif
 
 	e820_register_memory();
+	e820_mark_nosave_regions();
 
 #ifdef CONFIG_VT
 #if defined(CONFIG_VGA_CONSOLE)

include/asm-i386/e820.h

@@ -47,6 +47,14 @@ extern void e820_register_memory(void);
 extern void limit_regions(unsigned long long size);
 extern void print_memory_map(char *who);
 
+#if defined(CONFIG_PM) && defined(CONFIG_SOFTWARE_SUSPEND)
+extern void e820_mark_nosave_regions(void);
+#else
+static inline void e820_mark_nosave_regions(void)
+{
+}
+#endif
+
 #endif/*!__ASSEMBLY__*/
 
 #endif/*__E820_HEADER*/