[PATCH] Fix statically declare FIXMAPs

From: Anton Blanchard <anton@samba.org>, me.

Two uses of the FIXADDR_USER_START/END things are problematic:

a) ppc64 wants the FIXADDR area to be at a different location on 32bit and
   64bit tasks.  On 32bit we want it just below 4GB but that gets in the way
   on 64bit.  By putting both right at -(some small amount) we can also use
   some ppc tricks to get there real quickly (single instruction branches).

b) We assume that FIXADDR_USER_START and FIXADDR_USER_END are constants.
   This breaks the UML build.

Fixes:

- Call it all gate. We currently have half the stuff called fixmap and
  the other gate, lets be consistent.

- Create in_gate_area(), get_gate_vma() and use it in both places

- Provide defaults for in_gate_area/get_gate_vma, allowing an arch to
  override it. (I used CONFIG_* but am open to better suggestions here)

- The /proc/pid/maps vma wasnt marked readable but the get_user
  vma was. That sounds suspicious to me, they are now both the same VMA
  and so have the same (read,exec) permissions

1 files changed, 28 insertions, 0 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 42f5c2df91d1..3ecd3d633c5f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -642,5 +642,33 @@ kernel_map_pages(struct page *page, int numpages, int enable)
 }
 #endif
 
+#ifndef CONFIG_ARCH_GATE_AREA
+#ifdef AT_SYSINFO_EHDR
+static inline int in_gate_area(struct task_struct *task, unsigned long addr)
+{
+	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
+		return 1;
+	else
+		return 0;
+}
+
+extern struct vm_area_struct gate_vma;
+static inline struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
+{
+	return &gate_vma;
+}
+#else
+static inline int in_gate_area(struct task_struct *task, unsigned long addr)
+{
+	return 0;
+}
+
+static inline struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
+{
+	return NULL;
+}
+#endif
+#endif
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_H */