Place assembler functions in separate sections

This extends the --gc-sections behaviour to the many assembler
support functions in the firmware images by placing each function
into its own code section. This is achieved by creating a 'func'
macro used to declare each function label.

Fixes ARM-software/tf-issues#80

Change-Id: I301937b630add292d2dec6d2561a7fcfa6fec690
diff --git a/bl31/aarch64/runtime_exceptions.S b/bl31/aarch64/runtime_exceptions.S
index 223514e..e16d8d9 100644
--- a/bl31/aarch64/runtime_exceptions.S
+++ b/bl31/aarch64/runtime_exceptions.S
@@ -203,7 +203,6 @@
 
 	.align	7
 
-	.section	.text, "ax"
 	/* -----------------------------------------------------
 	 * The following code handles secure monitor calls.
 	 * Depending upon the execution state from where the SMC
@@ -217,6 +216,7 @@
 	 * used here
 	 * -----------------------------------------------------
 	 */
+func smc_handler
 smc_handler32:
 	/* Check whether aarch32 issued an SMC64 */
 	tbnz	x0, #FUNCID_CC_SHIFT, smc_prohibited
@@ -330,6 +330,9 @@
 	 * This routine assumes that the SP_EL3 is pointing to
 	 * a valid context structure from where the gp regs and
 	 * other special registers can be retrieved.
+	 *
+	 * Keep it in the same section as smc_handler as this
+	 * function uses a fall-through to el3_exit
 	 * -----------------------------------------------------
 	 */
 el3_exit: ; .type el3_exit, %function
@@ -383,7 +386,7 @@
 	 * within the 32 instructions per exception vector.
 	 * -----------------------------------------------------
 	 */
-save_scratch_registers: ; .type save_scratch_registers, %function
+func save_scratch_registers
 	stp	x0, x1, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X0]
 	stp	x2, x3, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X2]
 	stp	x4, x5, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X4]
@@ -397,7 +400,7 @@
 	stp	x18, x17, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X18]
 	ret
 
-restore_scratch_registers: ; .type restore_scratch_registers, %function
+func restore_scratch_registers
 	ldp	x0, x1, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X0]
 	ldp	x2, x3, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X2]
 
@@ -430,7 +433,7 @@
 	 * reporting unhandled exceptions
 	 * -----------------------------------------------------
 	 */
-get_exception_stack: ; .type get_exception_stack, %function
+func get_exception_stack
 	mov	x10, x30 // lr
 	bl	platform_get_core_pos
 	add	x0, x0, #1