powerpc: enable UBSAN support

This hooks up UBSAN support for PowerPC.

So far it's found some interesting cases where we don't properly sanitise
input to shifts, including one in our futex handling.  Nothing critical,
but interesting and worth fixing.

[valentinrothberg@gmail.com: arch/powerpc/Kconfig: fix typo in select statement]
Signed-off-by: Daniel Axtens <dja@axtens.net>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Valentin Rothberg <valentinrothberg@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/powerpc/Kconfig

@@ -158,6 +158,7 @@ config PPC
 	select ARCH_HAS_DMA_SET_COHERENT_MASK
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select HAVE_ARCH_SECCOMP_FILTER
+	select ARCH_HAS_UBSAN_SANITIZE_ALL
 
 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN

arch/powerpc/kernel/Makefile

@@ -136,12 +136,18 @@ endif
 obj-$(CONFIG_EPAPR_PARAVIRT)	+= epapr_paravirt.o epapr_hcalls.o
 obj-$(CONFIG_KVM_GUEST)		+= kvm.o kvm_emul.o
 
-# Disable GCOV in odd or sensitive code
+# Disable GCOV & sanitizers in odd or sensitive code
 GCOV_PROFILE_prom_init.o := n
+UBSAN_SANITIZE_prom_init.o := n
 GCOV_PROFILE_ftrace.o := n
+UBSAN_SANITIZE_ftrace.o := n
 GCOV_PROFILE_machine_kexec_64.o := n
+UBSAN_SANITIZE_machine_kexec_64.o := n
 GCOV_PROFILE_machine_kexec_32.o := n
+UBSAN_SANITIZE_machine_kexec_32.o := n
 GCOV_PROFILE_kprobes.o := n
+UBSAN_SANITIZE_kprobes.o := n
+UBSAN_SANITIZE_vdso.o := n
 
 extra-$(CONFIG_PPC_FPU)		+= fpu.o
 extra-$(CONFIG_ALTIVEC)		+= vector.o

arch/powerpc/kernel/vdso32/Makefile

@@ -15,6 +15,7 @@ targets := $(obj-vdso32) vdso32.so vdso32.so.dbg
 obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
 
 GCOV_PROFILE := n
+UBSAN_SANITIZE := n
 
 ccflags-y := -shared -fno-common -fno-builtin
 ccflags-y += -nostdlib -Wl,-soname=linux-vdso32.so.1 \

arch/powerpc/kernel/vdso64/Makefile

@@ -8,6 +8,7 @@ targets := $(obj-vdso64) vdso64.so vdso64.so.dbg
 obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
 
 GCOV_PROFILE := n
+UBSAN_SANITIZE := n
 
 ccflags-y := -shared -fno-common -fno-builtin
 ccflags-y += -nostdlib -Wl,-soname=linux-vdso64.so.1 \

arch/powerpc/xmon/Makefile

@@ -3,6 +3,7 @@
 subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
 
 GCOV_PROFILE := n
+UBSAN_SANITIZE := n
 
 ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)