From cd3557a7618bf5c1935e9f66b58a329f1f1f4b27 Mon Sep 17 00:00:00 2001 From: Thomas Weißschuh Date: Tue, 1 Jul 2025 10:58:06 +0200 Subject: vdso/gettimeofday: Add support for auxiliary clocks MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Expose the auxiliary clocks through the vDSO. Architectures not using the generic vDSO time framework, namely SPARC64, are not supported. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250701-vdso-auxclock-v1-12-df7d9f87b9b8@linutronix.de --- lib/vdso/gettimeofday.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 48 insertions(+), 1 deletion(-) (limited to 'lib') diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c index fc0038e83b5c..02ea19f67164 100644 --- a/lib/vdso/gettimeofday.c +++ b/lib/vdso/gettimeofday.c @@ -2,6 +2,7 @@ /* * Generic userspace implementations of gettimeofday() and similar. */ +#include #include #include @@ -74,7 +75,7 @@ static inline bool vdso_cycles_ok(u64 cycles) static __always_inline bool vdso_clockid_valid(clockid_t clock) { /* Check for negative values or invalid clocks */ - return likely((u32) clock < MAX_CLOCKS); + return likely((u32) clock <= CLOCK_AUX_LAST); } /* @@ -268,6 +269,48 @@ bool do_coarse(const struct vdso_time_data *vd, const struct vdso_clock *vc, return true; } +static __always_inline +bool do_aux(const struct vdso_time_data *vd, clockid_t clock, struct __kernel_timespec *ts) +{ + const struct vdso_clock *vc; + u32 seq, idx; + u64 sec, ns; + + if (!IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS)) + return false; + + idx = clock - CLOCK_AUX; + vc = &vd->aux_clock_data[idx]; + + do { + /* + * Open coded function vdso_read_begin() to handle + * VDSO_CLOCK_TIMENS. See comment in do_hres(). + */ + while ((seq = READ_ONCE(vc->seq)) & 1) { + if (IS_ENABLED(CONFIG_TIME_NS) && vc->clock_mode == VDSO_CLOCKMODE_TIMENS) { + vd = __arch_get_vdso_u_timens_data(vd); + vc = &vd->aux_clock_data[idx]; + /* Re-read from the real time data page */ + continue; + } + cpu_relax(); + } + smp_rmb(); + + /* Auxclock disabled? */ + if (vc->clock_mode == VDSO_CLOCKMODE_NONE) + return false; + + if (!vdso_get_timestamp(vd, vc, VDSO_BASE_AUX, &sec, &ns)) + return false; + } while (unlikely(vdso_read_retry(vc, seq))); + + vdso_set_timespec(ts, sec, ns); + + return true; +} + static __always_inline bool __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock, struct __kernel_timespec *ts) @@ -289,6 +332,8 @@ __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock, return do_coarse(vd, &vc[CS_HRES_COARSE], clock, ts); else if (msk & VDSO_RAW) vc = &vc[CS_RAW]; + else if (msk & VDSO_AUX) + return do_aux(vd, clock, ts); else return false; @@ -433,6 +478,8 @@ bool __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t cloc * Preserves the behaviour of posix_get_coarse_res(). */ ns = LOW_RES_NSEC; + } else if (msk & VDSO_AUX) { + ns = aux_clock_resolution_ns(); } else { return false; } -- cgit v1.2.3