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powerpc: Fix powerpc32/power7 memchr for large input sizes 

The same error fixed in commit b224637928
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.
This commit is contained in:
Tulio Magno Quites Machado Filho 2016-12-28 11:38:56 -02:00
parent 9314d3545e
commit 5e628dd118
2 changed files with 15 additions and 1 deletions
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5
ChangeLog
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@ -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

11
sysdeps/powerpc/powerpc32/power7/memchr.S
View File

@ -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