ARC: [lib] strchr breakage in Big-endian configuration

For a search buffer, 2 byte aligned, strchr() was returning pointer
outside of buffer (buf - 1)

------------->8----------------
    // Input buffer (default 4 byte aigned)
    char *buffer = "1AA_";

    // actual search start (to mimick 2 byte alignment)
    char *current_line = &(buffer[2]);

    // Character to search for
    char c = 'A';

    char *c_pos = strchr(current_line, c);

    printf("%s\n", c_pos) --> 'AA_' as oppose to 'A_'
------------->8----------------

Reported-by: Anton Kolesov <Anton.Kolesov@synopsys.com>
Debugged-by: Anton Kolesov <Anton.Kolesov@synopsys.com>
Cc: <stable@vger.kernel.org> # [3.9 and 3.10]
Cc: Noam Camus <noamc@ezchip.com>
Signed-off-by: Joern Rennecke  <joern.rennecke@embecosm.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/arc/lib/strchr-700.S b/arch/arc/lib/strchr-700.S
index 99c10475d477..9c548c7cf001 100644
--- a/arch/arc/lib/strchr-700.S
+++ b/arch/arc/lib/strchr-700.S
@@ -39,9 +39,18 @@ ARC_ENTRY strchr
         ld.a    r2,[r0,4]
         sub     r12,r6,r7
         bic     r12,r12,r6
+#ifdef __LITTLE_ENDIAN__
         and     r7,r12,r4
         breq    r7,0,.Loop ; For speed, we want this branch to be unaligned.
         b       .Lfound_char ; Likewise this one.
+#else
+        and     r12,r12,r4
+        breq    r12,0,.Loop ; For speed, we want this branch to be unaligned.
+        lsr_s   r12,r12,7
+        bic     r2,r7,r6
+        b.d     .Lfound_char_b
+        and_s   r2,r2,r12
+#endif
 ; /* We require this code address to be unaligned for speed...  */
 .Laligned:
         ld_s    r2,[r0]
@@ -95,6 +104,7 @@ ARC_ENTRY strchr
         lsr     r7,r7,7
 
         bic     r2,r7,r6
+.Lfound_char_b:
         norm    r2,r2
         sub_s   r0,r0,4
         asr_s   r2,r2,3