sh: Fixup various PAGE_SIZE == 4096 assumptions.

There were a number of places that made evil PAGE_SIZE == 4k
assumptions that ended up breaking when trying to play with
8k and 64k page sizes, this fixes those up.

The most significant change is the way we load THREAD_SIZE,
previously this was done via:

	mov	#(THREAD_SIZE >> 8), reg
	shll8	reg

to avoid a memory access and allow the immediate load. With
a 64k PAGE_SIZE, we're out of range for the immediate load
size without resorting to special instructions available in
later ISAs (movi20s and so on). The "workaround" for this is
to bump up the shift to 10 and insert a shll2, which gives a
bit more flexibility while still being much cheaper than a
memory access.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/sh/kernel/cpu/sh3/entry.S b/arch/sh/kernel/cpu/sh3/entry.S
index 5de99b498738..7ba3dcbe7504 100644
--- a/arch/sh/kernel/cpu/sh3/entry.S
+++ b/arch/sh/kernel/cpu/sh3/entry.S
@@ -335,7 +335,7 @@ general_exception:
 /* This code makes some assumptions to improve performance.
  * Make sure they are stil true. */
 #if PTRS_PER_PGD != PTRS_PER_PTE
-#error PDG and PTE sizes don't match
+#error PGD and PTE sizes don't match
 #endif
 
 /* gas doesn't flag impossible values for mov #immediate as an error */
@@ -547,8 +547,9 @@ ENTRY(handle_exception)
         bt/s    1f              ! It's a kernel to kernel transition.
          mov    r15, k0         ! save original stack to k0
         /* User space to kernel */
-        mov     #(THREAD_SIZE >> 8), k1
+        mov     #(THREAD_SIZE >> 10), k1
         shll8   k1              ! k1 := THREAD_SIZE
+        shll2   k1
         add     current, k1
         mov     k1, r15         ! change to kernel stack
         !