powerpc: Fix powerpc32/power7 memchr for large input sizes

The same error fixed in commit b224637928e9fc04e3cef3e10d02ccf042d01584
happens in the 32-bit implementation of memchr for power7.

This patch adopts the same solution, with a minimal change: it
implements a saturated addition where overflows sets the maximum pointer
size to UINTPTR_MAX.

diff --git a/ChangeLog b/ChangeLog
index d9b2c98..1ad6867 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2016-12-28  Tulio Magno Quites Machado Filho  <tuliom@linux.vnet.ibm.com>
+
+       * sysdeps/powerpc/powerpc32/power7/memchr.S (__memchr): Avoid an
+       overflow in pointer addition.
+
 2016-12-28  Rajalakshmi Srinivasaraghavan  <raji@linux.vnet.ibm.com>
 
        * sysdeps/powerpc/powerpc64/multiarch/Makefile

diff --git a/sysdeps/powerpc/powerpc32/power7/memchr.S b/sysdeps/powerpc/powerpc32/power7/memchr.S
index 318168b..5ce2bb0 100644 (file)
--- a/sysdeps/powerpc/powerpc32/power7/memchr.S
+++ b/sysdeps/powerpc/powerpc32/power7/memchr.S
@@ -26,7 +26,16 @@ ENTRY (__memchr)
        dcbt    0,r3
        clrrwi  r8,r3,2
        insrwi  r4,r4,8,16    /* Replicate byte to word.  */
-       add     r7,r3,r5      /* Calculate the last acceptable address.  */
+
+       /* Calculate the last acceptable address and check for possible
+          addition overflow by using satured math:
+          r7 = r3 + r5
+          r7 |= -(r7 < x)  */
+       add     r7,r3,r5
+       subfc   r6,r3,r7
+       subfe   r9,r9,r9
+       or      r7,r7,r9
+
        insrwi  r4,r4,16,0
        cmplwi  r5,16
        li      r9, -1