The arm_arch_timer requires that VDSO_CLOCKMODE_ARCHTIMER to be
defined to compile correctly. On arm the vDSO can be disabled and when
this is the case the compilation ends prematurely with an error:

 $ make ARCH=arm multi_v7_defconfig
 $ ./scripts/config -d VDSO
 $ make

drivers/clocksource/arm_arch_timer.c:73:44: error:
‘VDSO_CLOCKMODE_ARCHTIMER’ undeclared here (not in a function)
  static enum vdso_clock_mode vdso_default = VDSO_CLOCKMODE_ARCHTIMER;
                                             ^
scripts/Makefile.build:267: recipe for target
'drivers/clocksource/arm_arch_timer.o' failed
make[2]: *** [drivers/clocksource/arm_arch_timer.o] Error 1
make[2]: *** Waiting for unfinished jobs....
scripts/Makefile.build:505: recipe for target 'drivers/clocksource' 
failed
make[1]: *** [drivers/clocksource] Error 2
make[1]: *** Waiting for unfinished jobs....
Makefile:1683: recipe for target 'drivers' failed
make: *** [drivers] Error 2

Define VDSO_CLOCKMODE_ARCHTIMER as VDSO_CLOCKMODE_NONE when the vDSOs 
are
not enabled to address the issue.

Fixes: 5e3c6a312a09 ("ARM/arm64: vdso: Use common vdso clock mode 
storage")
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <redacted>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 drivers/clocksource/arm_arch_timer.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/clocksource/arm_arch_timer.c

b/drivers/clocksource/arm_arch_timer.c
index ee2420d56f67..619839221f94 100644

--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c

@@ -49,6 +49,11 @@
 #define CNTV_TVAL	0x38
 #define CNTV_CTL	0x3c

+#ifndef CONFIG_GENERIC_GETTIMEOFDAY
+/* The define below is required because on arm the VDSOs can be 

disabled */
+#define VDSO_CLOCKMODE_ARCHTIMER	VDSO_CLOCKMODE_NONE
+#endif /* CONFIG_GENERIC_GETTIMEOFDAY */