Take an effort to recode the arm64 vdso code from assembler to C previously submitted by Andrew Pinski <[email protected]>, rework it for use in both arm and arm64, overlapping any optimizations for each architecture. But instead of landing it in arm64, land the result into lib/vdso and unify both implementations to simplify future maintenance.
Add a case for CLOCK_BOOTTIME as it is popular for measuring relative time on systems expected to suspend() or hibernate(). Android uses CLOCK_BOOTTIME for all relative time measurements and timeouts. Switching to vdso reduced CPU utilization and improves accuracy. There is also a desire by some partners to switch all logging over to CLOCK_BOOTTIME, and thus this operation alone would contribute to a near percentile CPU load. Signed-off-by: Mark Salyzyn <[email protected]> Cc: James Morse <[email protected]> Cc: Russell King <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Will Deacon <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Dmitry Safonov <[email protected]> Cc: John Stultz <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Laura Abbott <[email protected]> Cc: Kees Cook <[email protected]> Cc: Ard Biesheuvel <[email protected]> Cc: Andy Gross <[email protected]> Cc: Kevin Brodsky <[email protected]> Cc: Andrew Pinski <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] v2: - rebased and changed from 3/3 to 10/10, fortified commit message. v3: - move arch/arm/vdso/vgettimeofday.c to lib/vdso/vgettimeofday.c. v4: - update commit message to reflect specific, and overall reasoning of patch series. - drop forced inline operations. - switch typeof() with __kernel_time_t. --- arch/arm/include/asm/vdso_datapage.h | 1 + arch/arm/kernel/vdso.c | 1 + arch/arm64/include/asm/vdso_datapage.h | 1 + arch/arm64/kernel/vdso.c | 1 + lib/vdso/vgettimeofday.c | 54 ++++++++++++++++++++++++++++++++++ 5 files changed, 58 insertions(+) diff --git a/arch/arm/include/asm/vdso_datapage.h b/arch/arm/include/asm/vdso_datapage.h index 1c6e6a5d5d9d..1adfb2daac3a 100644 --- a/arch/arm/include/asm/vdso_datapage.h +++ b/arch/arm/include/asm/vdso_datapage.h @@ -64,6 +64,7 @@ struct vdso_data { u32 tz_minuteswest; /* timezone info for gettimeofday(2) */ u32 tz_dsttime; + u64 btm_nsec; /* monotonic to boot time */ /* Raw clocksource multipler */ u32 cs_raw_mult; /* Raw time */ diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c index 287424541f3a..9370ab4b2734 100644 --- a/arch/arm/kernel/vdso.c +++ b/arch/arm/kernel/vdso.c @@ -347,6 +347,7 @@ void update_vsyscall(struct timekeeper *tk) /* tkr_mono.shift == tkr_raw.shift */ vdso_data->cs_shift = tk->tkr_mono.shift; vdso_data->cs_mask = tk->tkr_mono.mask; + vdso_data->btm_nsec = ktime_to_ns(tk->offs_boot); } vdso_write_end(vdso_data); diff --git a/arch/arm64/include/asm/vdso_datapage.h b/arch/arm64/include/asm/vdso_datapage.h index 95f4a7abab80..e4fa5e054708 100644 --- a/arch/arm64/include/asm/vdso_datapage.h +++ b/arch/arm64/include/asm/vdso_datapage.h @@ -45,6 +45,7 @@ struct vdso_data { __u64 xtime_coarse_nsec; __u64 wtm_clock_sec; /* Wall to monotonic time */ vdso_wtm_clock_nsec_t wtm_clock_nsec; + __u64 btm_nsec; /* monotonic to boot time */ __u32 tb_seq_count; /* Timebase sequence counter */ /* cs_* members must be adjacent and in this order (ldp accesses) */ __u32 cs_mono_mult; /* NTP-adjusted clocksource multiplier */ diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index 59f150c25889..0710edd8bedc 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -243,6 +243,7 @@ void update_vsyscall(struct timekeeper *tk) vdso_data->cs_raw_mult = tk->tkr_raw.mult; /* tkr_mono.shift == tkr_raw.shift */ vdso_data->cs_shift = tk->tkr_mono.shift; + vdso_data->btm_nsec = ktime_to_ns(tk->offs_boot); } smp_wmb(); diff --git a/lib/vdso/vgettimeofday.c b/lib/vdso/vgettimeofday.c index 0b585081f4de..4f500aba7e60 100644 --- a/lib/vdso/vgettimeofday.c +++ b/lib/vdso/vgettimeofday.c @@ -242,6 +242,49 @@ static notrace int do_monotonic_raw(const struct vdso_data *vd, return 0; } +static notrace int do_boottime(const struct vdso_data *vd, struct timespec *ts) +{ + u32 seq, mult, shift; + u64 nsec, cycle_last, wtm_nsec; +#ifdef ARCH_CLOCK_FIXED_MASK + static const u64 mask = ARCH_CLOCK_FIXED_MASK; +#else + u64 mask; +#endif + __kernel_time_t sec; + + do { + seq = vdso_read_begin(vd); + + if (vd->use_syscall) + return -1; + + cycle_last = vd->cs_cycle_last; + + mult = vd->cs_mono_mult; + shift = vd->cs_shift; +#ifndef ARCH_CLOCK_FIXED_MASK + mask = vd->cs_mask; +#endif + + sec = vd->xtime_clock_sec; + nsec = vd->xtime_clock_snsec; + + sec += vd->wtm_clock_sec; + wtm_nsec = vd->wtm_clock_nsec + vd->btm_nsec; + + } while (unlikely(vdso_read_retry(vd, seq))); + + nsec += get_clock_shifted_nsec(cycle_last, mult, mask); + nsec >>= shift; + nsec += wtm_nsec; + + ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec); + ts->tv_nsec = nsec; + + return 0; +} + #else /* ARCH_PROVIDES_TIMER */ static notrace int do_realtime(const struct vdso_data *vd, struct timespec *ts) @@ -260,6 +303,12 @@ static notrace int do_monotonic_raw(const struct vdso_data *vd, return -1; } +static notrace int do_boottime(const struct vdso_data *vd, + struct timespec *ts) +{ + return -1; +} + #endif /* ARCH_PROVIDES_TIMER */ notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts) @@ -285,6 +334,10 @@ notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts) if (do_monotonic_raw(vd, ts)) goto fallback; break; + case CLOCK_BOOTTIME: + if (do_boottime(vd, ts)) + goto fallback; + break; default: goto fallback; } @@ -321,6 +374,7 @@ int __vdso_clock_getres(clockid_t clock, struct timespec *res) long nsec; if (clock == CLOCK_REALTIME || + clock == CLOCK_BOOTTIME || clock == CLOCK_MONOTONIC || clock == CLOCK_MONOTONIC_RAW) nsec = MONOTONIC_RES_NSEC; -- 2.15.0.rc2.357.g7e34df9404-goog
