[PATCH] MIPS:wrong usage of l_exc_copy in octeon-memcpy.S

From: jianchao.wang
Date: Sun Feb 19 2017 - 22:50:03 EST

l_exc_copy() is usually to be used like this:
1 EXC( LOAD t0, UNIT(0)(src), l_exc)
2 EXC( LOAD t1, UNIT(1)(src), l_exc_copy)
3 EXC( LOAD t2, UNIT(2)(src), l_exc_copy)
4 EXC( LOAD t3, UNIT(3)(src), l_exc_copy)
When the fault occurs on row 4, l_exc_copy will get the bad
addr through THREAD_BUADDR(), complete the copy of row
1,2 and 3, and then return the len that has not been copied.
l_exc_copy assumes the src is smaller thann the bad addr.It will
increase src by 1 until reach the bad addr.

octeon-memcpy.S use the l_exc_copy with wrong way which make src
could be greater than bad addr. We will fix it in this patch.
We add the max offset of LOAD to 15 here to fix the issue without
adding new commands . Howerver, the side effect is that, when LOAD
fails in few case, l_exc_copy has to copy more.

Signed-off-by: jianchao.wang <jianchao.wan9@xxxxxxxxx>
arch/mips/cavium-octeon/octeon-memcpy.S | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/arch/mips/cavium-octeon/octeon-memcpy.S b/arch/mips/cavium-octeon/octeon-memcpy.S
index 64e08df..b0fe98e 100644
--- a/arch/mips/cavium-octeon/octeon-memcpy.S
+++ b/arch/mips/cavium-octeon/octeon-memcpy.S
@@ -205,22 +205,22 @@ EXC( LOAD t3, UNIT(7)(src), l_exc_copy)
EXC( STORE t0, UNIT(4)(dst), s_exc_p12u)
EXC( STORE t1, UNIT(5)(dst), s_exc_p11u)
EXC( STORE t2, UNIT(6)(dst), s_exc_p10u)
- ADD src, src, 16*NBYTES
EXC( STORE t3, UNIT(7)(dst), s_exc_p9u)
+EXC( LOAD t0, UNIT(8)(src), l_exc_copy)
+EXC( LOAD t1, UNIT(9)(src), l_exc_copy)
+EXC( LOAD t2, UNIT(10)(src), l_exc_copy)
+EXC( LOAD t3, UNIT(11)(src), l_exc_copy)
+EXC( STORE t0, UNIT(8)(dst), s_exc_p8u)
+EXC( STORE t1, UNIT(9)(dst), s_exc_p7u)
+EXC( STORE t2, UNIT(10)(dst), s_exc_p6u)
+EXC( STORE t3, UNIT(11)(dst), s_exc_p5u)
+EXC( LOAD t0, UNIT(12)(src), l_exc_copy)
+EXC( LOAD t1, UNIT(13)(src), l_exc_copy)
+EXC( LOAD t2, UNIT(14)(src), l_exc_copy)
+EXC( LOAD t3, UNIT(15)(src), l_exc_copy)
ADD dst, dst, 16*NBYTES
-EXC( LOAD t0, UNIT(-8)(src), l_exc_copy)
-EXC( LOAD t1, UNIT(-7)(src), l_exc_copy)
-EXC( LOAD t2, UNIT(-6)(src), l_exc_copy)
-EXC( LOAD t3, UNIT(-5)(src), l_exc_copy)
-EXC( STORE t0, UNIT(-8)(dst), s_exc_p8u)
-EXC( STORE t1, UNIT(-7)(dst), s_exc_p7u)
-EXC( STORE t2, UNIT(-6)(dst), s_exc_p6u)
-EXC( STORE t3, UNIT(-5)(dst), s_exc_p5u)
-EXC( LOAD t0, UNIT(-4)(src), l_exc_copy)
-EXC( LOAD t1, UNIT(-3)(src), l_exc_copy)
-EXC( LOAD t2, UNIT(-2)(src), l_exc_copy)
-EXC( LOAD t3, UNIT(-1)(src), l_exc_copy)
EXC( STORE t0, UNIT(-4)(dst), s_exc_p4u)
+ ADD src, src, 16*NBYTES
EXC( STORE t1, UNIT(-3)(dst), s_exc_p3u)
EXC( STORE t2, UNIT(-2)(dst), s_exc_p2u)
EXC( STORE t3, UNIT(-1)(dst), s_exc_p1u)