ARM: msm: fix compilation flags for MSM_SCM

CONFIG_MSM_SCM uses the smc instruction, which with some
toolchains requires a ".arch_extension" directive.

Cc: David Brown <davidb@codeaurora.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: David Brown <davidb@codeaurora.org>

arch/arm/mach-msm/Makefile

@@ -15,6 +15,8 @@ obj-$(CONFIG_MSM_SMD) += smd.o smd_debug.o
 obj-$(CONFIG_MSM_SMD) += last_radio_log.o
 obj-$(CONFIG_MSM_SCM) += scm.o scm-boot.o
 
+CFLAGS_scm.o :=$(call as-instr,.arch_extension sec,-DREQUIRES_SEC=1)
+
 obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
 obj-$(CONFIG_SMP) += headsmp.o platsmp.o
 

arch/arm/mach-msm/scm.c

@@ -180,6 +180,9 @@ static u32 smc(u32 cmd_addr)
 			__asmeq("%1", "r0")
 			__asmeq("%2", "r1")
 			__asmeq("%3", "r2")
+#ifdef REQUIRES_SEC
+			".arch_extension sec\n"
+#endif
 			"smc	#0	@ switch to secure world\n"
 			: "=r" (r0)
 			: "r" (r0), "r" (r1), "r" (r2)