On Mon, Apr 01, 2019 at 12:51:48PM +0100, Vincenzo Frascino wrote: > diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c > index 2d419006ad43..47ba72345739 100644 > --- a/arch/arm64/kernel/vdso.c > +++ b/arch/arm64/kernel/vdso.c > @@ -245,6 +245,8 @@ void update_vsyscall(struct timekeeper *tk) > vdso_data->cs_shift = tk->tkr_mono.shift; > } > > + vdso_data->hrtimer_res = hrtimer_resolution; > + > smp_wmb(); > ++vdso_data->tb_seq_count; > } > diff --git a/arch/arm64/kernel/vdso/gettimeofday.S > b/arch/arm64/kernel/vdso/gettimeofday.S > index c39872a7b03c..7a2cd2f8e13a 100644 > --- a/arch/arm64/kernel/vdso/gettimeofday.S > +++ b/arch/arm64/kernel/vdso/gettimeofday.S > @@ -296,32 +296,35 @@ ENDPROC(__kernel_clock_gettime) > /* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res); */ > ENTRY(__kernel_clock_getres) > .cfi_startproc > + adr vdso_data, _vdso_data > cmp w0, #CLOCK_REALTIME > ccmp w0, #CLOCK_MONOTONIC, #0x4, ne > ccmp w0, #CLOCK_MONOTONIC_RAW, #0x4, ne > - b.ne 1f > + b.ne 2f > > - ldr x2, 5f > - b 2f > -1: > +1: /* Get hrtimer_res */ > + seqcnt_acquire > + syscall_check fail=5f > + ldr x2, [vdso_data, #CLOCK_REALTIME_RES] > + seqcnt_check fail=1b > + b 3f > +2:
We talked briefly but I'm still confused why we need the fallback to the syscall here if archdata.vdso_direct is false. Is it because if the timer driver code sets vdso_direct to false, we don't don't support highres timers? If my understanding is correct, you may want to move the hrtimer_res setting in update_vsyscall() to the !use_syscall block. -- Catalin
