x86/vdso: Replace the clockid switch case

[thirdparty/kernel/stable.git] / arch / x86 / entry / vdso / vclock_gettime.c

diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index b27dea0e23af058d599466849235e03ad36a3231..672e50e35d6c277d889915f1fe0ca2ea2b5dc563 100644 (file)
--- 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")));