1 files changed, 54 insertions, 0 deletions

diff --git a/arch/sh/lib64/clear_page.S b/arch/sh/lib64/clear_page.S
new file mode 100644
index 000000000000..007ab48ecc1c
--- /dev/null
+++ b/arch/sh/lib64/clear_page.S
@@ -0,0 +1,54 @@
+/*
+   Copyright 2003 Richard Curnow, SuperH (UK) Ltd.
+
+   This file is subject to the terms and conditions of the GNU General Public
+   License.  See the file "COPYING" in the main directory of this archive
+   for more details.
+
+   Tight version of memset for the case of just clearing a page.  It turns out
+   that having the alloco's spaced out slightly due to the increment/branch
+   pair causes them to contend less for access to the cache.  Similarly,
+   keeping the stores apart from the allocos causes less contention.  => Do two
+   separate loops.  Do multiple stores per loop to amortise the
+   increment/branch cost a little.
+
+   Parameters:
+   r2 : source effective address (start of page)
+
+   Always clears 4096 bytes.
+
+   Note : alloco guarded by synco to avoid TAKum03020 erratum
+
+*/
+
+        .section .text..SHmedia32,"ax"
+        .little
+
+        .balign 8
+        .global clear_page
+clear_page:
+        pta/l 1f, tr1
+        pta/l 2f, tr2
+        ptabs/l r18, tr0
+
+        movi 4096, r7
+        add  r2, r7, r7
+        add  r2, r63, r6
+1:
+        alloco r6, 0
+        synco   ! TAKum03020
+        addi    r6, 32, r6
+        bgt/l   r7, r6, tr1
+
+        add  r2, r63, r6
+2:
+        st.q  r6,   0, r63
+        st.q  r6,   8, r63
+        st.q  r6,  16, r63
+        st.q  r6,  24, r63
+        addi r6, 32, r6
+        bgt/l r7, r6, tr2
+
+        blink tr0, r63
+
+