x86/vdso: Enforce 64bit clocksource

All VDSO clock sources are TSC based and use CLOCKSOURCE_MASK(64). There is
no point in masking with all FF. Get rid of it and enforce the mask in the
sanity checker.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20180917130707.151963007@linutronix.de

diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index e48ca3afa0912cc8bb03bd6dba84b0999abe1982..6a950854034fd2ec952aa6fb47d23d256c12d995 100644 (file)
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -201,7 +201,7 @@ notrace static inline u64 vgetsns(int *mode)
 #endif
        else
                return 0;
-       v = (cycles - gtod->cycle_last) & gtod->mask;
+       v = cycles - gtod->cycle_last;
        return v * gtod->mult;
 }
 

diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c
index 1fa632e0829f64b9fe01d28c40d523039229d595..b23f5420b26a244d0406e06494719851b4ce3ad7 100644 (file)
--- a/arch/x86/kernel/time.c
+++ b/arch/x86/kernel/time.c
@@ -120,4 +120,10 @@ void clocksource_arch_init(struct clocksource *cs)
                        cs->name, cs->archdata.vclock_mode);
                cs->archdata.vclock_mode = VCLOCK_NONE;
        }
+
+       if (cs->mask != CLOCKSOURCE_MASK(64)) {
+               pr_warn("clocksource %s registered with invalid mask %016llx. Disabling vclock.\n",
+                       cs->name, cs->mask);
+               cs->archdata.vclock_mode = VCLOCK_NONE;
+       }
 }