diff --git a/arch/arm64/kernel/vdso/gettimeofday.c b/arch/arm64/kernel/vdso/gettimeofday.c index 12937865bd9534470352a78e02272ef4177c5257..79eaabb4c6fab75773236574f67d55aa809e7edb 100644 --- a/arch/arm64/kernel/vdso/gettimeofday.c +++ b/arch/arm64/kernel/vdso/gettimeofday.c @@ -112,13 +112,24 @@ static notrace u32 vdso_read_retry(const struct vdso_data *vd, u32 start) * Returns the clock delta, in nanoseconds left-shifted by the clock * shift. */ -static notrace u64 get_clock_shifted_nsec(u64 cycle_last, u64 mult) +static notrace u64 get_clock_shifted_nsec(u64 cycle_last, u64 mult, bool vdso_fix) { u64 res; /* Read the virtual counter. */ isb(); asm volatile("mrs %0, cntvct_el0" : "=r" (res) :: "memory"); + if (vdso_fix) { + u64 new; + int retries = 50; + + asm volatile("mrs %0, cntvct_el0" : "=r" (new) :: "memory"); + while (unlikely((new - res) >> 5) && retries) { + asm volatile("mrs %0, cntvct_el0" : "=r" (res) :: "memory"); + asm volatile("mrs %0, cntvct_el0" : "=r" (new) :: "memory"); + retries--; + } + } res = res - cycle_last; /* We can only guarantee 56 bits of precision. */ @@ -150,7 +161,7 @@ static __always_inline notrace int do_realtime(const struct vdso_data *vd, } while (unlikely(vdso_read_retry(vd, seq))); - ns += get_clock_shifted_nsec(cycle_last, cs_mono_mult); + ns += get_clock_shifted_nsec(cycle_last, cs_mono_mult, vd->vdso_fix); ns >>= cs_shift; ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); ts->tv_nsec = ns; @@ -183,7 +194,7 @@ static notrace int do_monotonic(const struct vdso_data *vd, } while (unlikely(vdso_read_retry(vd, seq))); - ns += get_clock_shifted_nsec(cycle_last, cs_mono_mult); + ns += get_clock_shifted_nsec(cycle_last, cs_mono_mult, vd->vdso_fix); ns >>= cs_shift; ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); @@ -214,7 +225,7 @@ static notrace int do_monotonic_raw(const struct vdso_data *vd, } while (unlikely(vdso_read_retry(vd, seq))); - ns += get_clock_shifted_nsec(cycle_last, cs_raw_mult); + ns += get_clock_shifted_nsec(cycle_last, cs_raw_mult, vd->vdso_fix); ns >>= cs_shift; ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); ts->tv_nsec = ns;