x86: fix early_ioremap()/btmap
fix a long-standing weakness of the early-ioremap allocator: it
uses a single pgd entry for the boot mappings, and was not properly
protecting itself against crossing a 2MB (4MB) boundary.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/asm-x86/fixmap_32.h b/include/asm-x86/fixmap_32.h
index 46bedb7..fde140f 100644
--- a/include/asm-x86/fixmap_32.h
+++ b/include/asm-x86/fixmap_32.h
@@ -90,10 +90,18 @@
FIX_PARAVIRT_BOOTMAP,
#endif
__end_of_permanent_fixed_addresses,
- /* temporary boot-time mappings, used before ioremap() is functional */
+ /*
+ * 256 temporary boot-time mappings, used by early_ioremap(),
+ * before ioremap() is functional.
+ *
+ * We round it up to the next 512 pages boundary so that we
+ * can have a single pgd entry and a single pte table:
+ */
#define NR_FIX_BTMAPS 64
#define FIX_BTMAPS_NESTING 4
- FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
+ FIX_BTMAP_END =
+ __end_of_permanent_fixed_addresses + 512 -
+ (__end_of_permanent_fixed_addresses & 511),
FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS*FIX_BTMAPS_NESTING - 1,
FIX_WP_TEST,
__end_of_fixed_addresses