x86: fix the missing BIOS area check in page_is_ram

page_is_ram has a FIXME since ages, which reminds to sanity check the
BIOS area between 640k and 1M, which is sometimes falsely reported as
RAM in the e820 tables.

Implement the sanity check. Move the BIOS range defines from
pageattr.c into e820.h to avoid duplicate defines.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 10 insertions, 5 deletions

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index d3026e1906f9..24e42cab8d58 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -42,13 +42,18 @@ int page_is_ram(unsigned long pagenr)
                  */
                 if (e820.map[i].type != E820_RAM)
                         continue;
-                /*
-                 *      !!!FIXME!!! Some BIOSen report areas as RAM that
-                 *      are not. Notably the 640->1Mb area. We need a sanity
-                 *      check here.
-                 */
                 addr = (e820.map[i].addr + PAGE_SIZE-1) >> PAGE_SHIFT;
                 end = (e820.map[i].addr + e820.map[i].size) >> PAGE_SHIFT;
+
+                /*
+                 * Sanity check: Some BIOSen report areas as RAM that
+                 * are not. Notably the 640->1Mb area, which is the
+                 * PCI BIOS area.
+                 */
+                if (addr >= (BIOS_BEGIN >> PAGE_SHIFT) &&
+                    end < (BIOS_END >> PAGE_SHIFT))
+                        continue;
+
                 if ((pagenr >= addr) && (pagenr < end))
                         return 1;
         }