[IA64] Fill holes in FIXADDR_USER space with zero pages.

This fixes an oops reported by Jason Baron.
Signed-off-by: David Mosberger-Tang <davidm@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/mm/init.c

@@ -305,8 +305,9 @@ setup_gate (void)
 	struct page *page;
 
 	/*
-	 * Map the gate page twice: once read-only to export the ELF headers etc. and once
-	 * execute-only page to enable privilege-promotion via "epc":
+	 * Map the gate page twice: once read-only to export the ELF
+	 * headers etc. and once execute-only page to enable
+	 * privilege-promotion via "epc":
 	 */
 	page = virt_to_page(ia64_imva(__start_gate_section));
 	put_kernel_page(page, GATE_ADDR, PAGE_READONLY);
@@ -315,6 +316,20 @@ setup_gate (void)
 	put_kernel_page(page, GATE_ADDR + PAGE_SIZE, PAGE_GATE);
 #else
 	put_kernel_page(page, GATE_ADDR + PERCPU_PAGE_SIZE, PAGE_GATE);
+	/* Fill in the holes (if any) with read-only zero pages: */
+	{
+		unsigned long addr;
+
+		for (addr = GATE_ADDR + PAGE_SIZE;
+		     addr < GATE_ADDR + PERCPU_PAGE_SIZE;
+		     addr += PAGE_SIZE)
+		{
+			put_kernel_page(ZERO_PAGE(0), addr,
+					PAGE_READONLY);
+			put_kernel_page(ZERO_PAGE(0), addr + PERCPU_PAGE_SIZE,
+					PAGE_READONLY);
+		}
+	}
 #endif
 	ia64_patch_gate();
 }

include/asm-ia64/pgtable.h

@@ -8,7 +8,7 @@
  * This hopefully works with any (fixed) IA-64 page-size, as defined
  * in <asm/page.h>.
  *
- * Copyright (C) 1998-2004 Hewlett-Packard Co
+ * Copyright (C) 1998-2005 Hewlett-Packard Co
  *	David Mosberger-Tang <davidm@hpl.hp.com>
  */
 
@@ -551,7 +551,11 @@ do {											\
 
 /* These tell get_user_pages() that the first gate page is accessible from user-level.  */
 #define FIXADDR_USER_START	GATE_ADDR
-#define FIXADDR_USER_END	(GATE_ADDR + 2*PERCPU_PAGE_SIZE)
+#ifdef HAVE_BUGGY_SEGREL
+# define FIXADDR_USER_END	(GATE_ADDR + 2*PAGE_SIZE)
+#else
+# define FIXADDR_USER_END	(GATE_ADDR + 2*PERCPU_PAGE_SIZE)
+#endif
 
 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY