1 files changed, 18 insertions, 20 deletions

diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index b27dea0e23af..672e50e35d6c 100644
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -241,29 +241,27 @@ notrace static void do_coarse(clockid_t clk, struct timespec *ts)
 
 notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
 {
-        switch (clock) {
-        case CLOCK_REALTIME:
-                if (do_hres(CLOCK_REALTIME, ts) == VCLOCK_NONE)
-                        goto fallback;
-                break;
-        case CLOCK_MONOTONIC:
-                if (do_hres(CLOCK_MONOTONIC, ts) == VCLOCK_NONE)
-                        goto fallback;
-                break;
-        case CLOCK_REALTIME_COARSE:
-                do_coarse(CLOCK_REALTIME_COARSE, ts);
-                break;
-        case CLOCK_MONOTONIC_COARSE:
-                do_coarse(CLOCK_MONOTONIC_COARSE, ts);
-                break;
-        default:
-                goto fallback;
-        }
+        unsigned int msk;
 
-        return 0;
-fallback:
+        /* Sort out negative (CPU/FD) and invalid clocks */
+        if (unlikely((unsigned int) clock >= MAX_CLOCKS))
+                return vdso_fallback_gettime(clock, ts);
+
+        /*
+         * Convert the clockid to a bitmask and use it to check which
+         * clocks are handled in the VDSO directly.
+         */
+        msk = 1U << clock;
+        if (likely(msk & VGTOD_HRES)) {
+                if (do_hres(clock, ts) != VCLOCK_NONE)
+                        return 0;
+        } else if (msk & VGTOD_COARSE) {
+                do_coarse(clock, ts);
+                return 0;
+        }
         return vdso_fallback_gettime(clock, ts);
 }
+
 int clock_gettime(clockid_t, struct timespec *)
         __attribute__((weak, alias("__vdso_clock_gettime")));