lib/vdso: Avoid highres update if clocksource is not VDSO capable

If the current clocksource is not VDSO capable there is no point in
updating the high resolution parts of the VDSO data.

Replace the architecture specific check with a check for a VDSO capable
clocksource and skip the update if there is none.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lkml.kernel.org/r/20200207124403.563379423@linutronix.de

diff --git a/arch/arm/include/asm/vdso/vsyscall.h b/arch/arm/include/asm/vdso/vsyscall.h
index 002f9edd8a2b37d936076c875fdbc438a921cc4b..47e41ae8ccd0b997b54dda59abea8ae98bbe3c56 100644 (file)
--- a/arch/arm/include/asm/vdso/vsyscall.h
+++ b/arch/arm/include/asm/vdso/vsyscall.h
@@ -21,13 +21,6 @@ struct vdso_data *__arm_get_k_vdso_data(void)
 }
 #define __arch_get_k_vdso_data __arm_get_k_vdso_data
 
-static __always_inline
-bool __arm_update_vdso_data(void)
-{
-       return cntvct_ok;
-}
-#define __arch_update_vdso_data __arm_update_vdso_data
-
 static __always_inline
 void __arm_sync_vdso_data(struct vdso_data *vdata)
 {

diff --git a/include/asm-generic/vdso/vsyscall.h b/include/asm-generic/vdso/vsyscall.h
index 4a28797495d7965753952566d0e3fc56f036a60d..c835607f78ae990e7479878767b05cccd3a99837 100644 (file)
--- a/include/asm-generic/vdso/vsyscall.h
+++ b/include/asm-generic/vdso/vsyscall.h
@@ -11,13 +11,6 @@ static __always_inline struct vdso_data *__arch_get_k_vdso_data(void)
 }
 #endif /* __arch_get_k_vdso_data */
 
-#ifndef __arch_update_vdso_data
-static __always_inline bool __arch_update_vdso_data(void)
-{
-       return true;
-}
-#endif /* __arch_update_vdso_data */
-
 #ifndef __arch_update_vsyscall
 static __always_inline void __arch_update_vsyscall(struct vdso_data *vdata,
                                                   struct timekeeper *tk)

diff --git a/kernel/time/vsyscall.c b/kernel/time/vsyscall.c
index d31a5ef4ade51bfcf3bf446e95f351b3d255c2aa..54ce6eb2ca36db6f34a07ac8dac3ae6f0814a01b 100644 (file)
--- a/kernel/time/vsyscall.c
+++ b/kernel/time/vsyscall.c
@@ -105,10 +105,10 @@ void update_vsyscall(struct timekeeper *tk)
        WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution);
 
        /*
-        * Architectures can opt out of updating the high resolution part
-        * of the VDSO.
+        * If the current clocksource is not VDSO capable, then spare the
+        * update of the high reolution parts.
         */
-       if (__arch_update_vdso_data())
+       if (clock_mode != VDSO_CLOCKMODE_NONE)
                update_vdso_data(vdata, tk);
 
        __arch_update_vsyscall(vdata, tk);