[MIPS] Fix 64-bit IP checksum code

Use unsigned loads to avoid possible misscalculation of IP checksums.  This
bug was instruced in f761106cd728bcf65b7fe161b10221ee00cf7132 (lmo) /
ed99e2bc1dc5dc54eb5a019f4975562dbef20103 (kernel.org).

[Original fix by Atsushi.  Improved instruction scheduling and fix for
unaligned unsigned load by me -- Ralf]

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/lib/csum_partial.S b/arch/mips/lib/csum_partial.S
index 8d77841..edac989 100644 (file)
--- a/arch/mips/lib/csum_partial.S
+++ b/arch/mips/lib/csum_partial.S
@@ -39,12 +39,14 @@
 #ifdef USE_DOUBLE
 
 #define LOAD   ld
+#define LOAD32 lwu
 #define ADD    daddu
 #define NBYTES 8
 
 #else
 
 #define LOAD   lw
+#define LOAD32 lw
 #define ADD    addu
 #define NBYTES 4
 
@@ -60,6 +62,14 @@
        ADD     sum, v1;                                        \
        .set    pop
 
+#define ADDC32(sum,reg)                                                \
+       .set    push;                                           \
+       .set    noat;                                           \
+       addu    sum, reg;                                       \
+       sltu    v1, sum, reg;                                   \
+       addu    sum, v1;                                        \
+       .set    pop
+
 #define CSUM_BIGCHUNK1(src, offset, sum, _t0, _t1, _t2, _t3)   \
        LOAD    _t0, (offset + UNIT(0))(src);                   \
        LOAD    _t1, (offset + UNIT(1))(src);                   \
@@ -132,7 +142,7 @@ LEAF(csum_partial)
        beqz    t8, .Lqword_align
         andi   t8, src, 0x8
 
-       lw      t0, 0x00(src)
+       LOAD32  t0, 0x00(src)
        LONG_SUBU       a1, a1, 0x4
        ADDC(sum, t0)
        PTR_ADDU        src, src, 0x4
@@ -211,7 +221,7 @@ LEAF(csum_partial)
        LONG_SRL        t8, t8, 0x2
 
 .Lend_words:
-       lw      t0, (src)
+       LOAD32  t0, (src)
        LONG_SUBU       t8, t8, 0x1
        ADDC(sum, t0)
        .set    reorder                         /* DADDI_WAR */
@@ -230,6 +240,9 @@ LEAF(csum_partial)
        /* Still a full word to go  */
        ulw     t1, (src)
        PTR_ADDIU       src, 4
+#ifdef USE_DOUBLE
+       dsll    t1, t1, 32                      /* clear lower 32bit */
+#endif
        ADDC(sum, t1)
 
 1:     move    t1, zero
@@ -280,7 +293,7 @@ LEAF(csum_partial)
 1:
        .set    reorder
        /* Add the passed partial csum.  */
-       ADDC(sum, a2)
+       ADDC32(sum, a2)
        jr      ra
        .set    noreorder
        END(csum_partial)
@@ -681,7 +694,7 @@ EXC(        sb      t0, NBYTES-2(dst), .Ls_exc)
        .set    pop
 1:
        .set reorder
-       ADDC(sum, psum)
+       ADDC32(sum, psum)
        jr      ra
        .set noreorder