ARM: Keep exit text/data around for SMP_ON_UP

When SMP_ON_UP is used and the spinlocks are inlined, we end up with
inline spinlocks in the exit code, with references from the SMP
alternatives section to the exit sections. This causes link time
errors. Avoid this by placing the exit sections in the init-discarded
region.

Cc: <[e-mail]>
Tested-by: Dave Martin <[e-mail]>
Signed-off-by: Russell King <[e-mail]>

arch/arm/kernel/vmlinux.lds.S

···
 #define ARM_CPU_KEEP(x)
 #endif
 
+#if defined(CONFIG_SMP_ON_UP) && !defined(CONFIG_DEBUG_SPINLOCK)
+#define ARM_EXIT_KEEP(x)	x
+#else
+#define ARM_EXIT_KEEP(x)
+#endif
+
 OUTPUT_ARCH(arm)
 ENTRY(stext)
 
···
 		_sinittext = .;
 			HEAD_TEXT
 			INIT_TEXT
+			ARM_EXIT_KEEP(EXIT_TEXT)
 		_einittext = .;
 		ARM_CPU_DISCARD(PROC_INFO)
 		__arch_info_begin = .;
···
 #ifndef CONFIG_XIP_KERNEL
 		__init_begin = _stext;
 		INIT_DATA
+		ARM_EXIT_KEEP(EXIT_DATA)
 #endif
 	}
 
···
 		. = ALIGN(PAGE_SIZE);
 		__init_begin = .;
 		INIT_DATA
+		ARM_EXIT_KEEP(EXIT_DATA)
 		. = ALIGN(PAGE_SIZE);
 		__init_end = .;
 #endif