diff mbox series

[v5,4/6] lib/vdso: Allow fixed clock mode

Message ID 47500ae9aa628aead4c5b5a71d5279268cdddb48.1580399657.git.christophe.leroy@c-s.fr (mailing list archive)
State New, archived
Headers show
Series powerpc: switch VDSO to C implementation. | expand

Commit Message

Christophe Leroy Jan. 30, 2020, 4:08 p.m. UTC 
Some architectures have a fixed clocksource which is known at compile
time and cannot be replaced or disabled at runtime, e.g. timebase on
PowerPC. For such cases the clock mode check in the VDSO code is
pointless.

Therefore, give architectures the opportunity to redefine the way
clock_mode is checked by moving the check into an
__arch_vdso_capable() macro.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 lib/vdso/gettimeofday.c | 6 ++++++
 1 file changed, 6 insertions(+)
diff mbox series

Patch

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 72d65dd50cb4..0b4b71880f22 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -120,12 +120,18 @@  static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
 			cpu_relax();
 		}
 		smp_rmb();
+#ifdef __arch_vdso_capable
+		if (unlikely(!__arch_vdso_capable(vd->clock_mode)))
+			return -1;
+#endif
 
 		cycles = __arch_get_hw_counter(vd->clock_mode);
 		ns = vdso_ts->nsec;
 		last = vd->cycle_last;
+#ifndef __arch_vdso_capable
 		if (unlikely((s64)cycles < 0))
 			return -1;
+#endif
 
 		ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
 		ns >>= vd->shift;