[PATCH] ppc64: Fix v_regs pointer setup

During some signal test, we found that v_regs pointer was not setup
correctly.  v_regs was made to point to itself, as a result of which the
pointer was corrupted when vec registers were copied over.  When the signal
handler returned, restore_sigcontext tried derefering the invalid pointer
and in the process killed the app with SIGSEGV.
Signed-off-by: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/kernel/signal.c

@@ -127,7 +127,7 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 	 * v_regs pointer or not
 	 */
 #ifdef CONFIG_ALTIVEC
-	elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve) & ~0xful);
+	elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful);
 #endif
 	long err = 0;