powerpc: Rearrange SLB preload code

With the new top down layout it is likely that the pc and stack will be in the
same segment, because the pc is most likely in a library allocated via a top
down mmap. Right now we bail out early if these segments match.

Rearrange the SLB preload code to sanity check all SLB preload addresses
are not in the kernel, then check all addresses for conflicts.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 5b7038f248b60ea5b7b7d1e0f432a5dad5fa285e..227056c21eee3f150e286a8528a886c3b5457cf0 100644 (file)
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -218,23 +218,18 @@ void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
        else
                unmapped_base = TASK_UNMAPPED_BASE_USER64;
 
-       if (is_kernel_addr(pc))
-               return;
-       slb_allocate(pc);
-
-       if (esids_match(pc,stack))
+       if (is_kernel_addr(pc) || is_kernel_addr(stack) ||
+           is_kernel_addr(unmapped_base))
                return;
 
-       if (is_kernel_addr(stack))
-               return;
-       slb_allocate(stack);
+       slb_allocate(pc);
 
-       if (esids_match(pc,unmapped_base) || esids_match(stack,unmapped_base))
-               return;
+       if (!esids_match(pc, stack))
+               slb_allocate(stack);
 
-       if (is_kernel_addr(unmapped_base))
-               return;
-       slb_allocate(unmapped_base);
+       if (!esids_match(pc, unmapped_base) &&
+           !esids_match(stack, unmapped_base))
+               slb_allocate(unmapped_base);
 }
 
 static inline void patch_slb_encoding(unsigned int *insn_addr,