timekeeping: Prepare do_adtimex() for auxiliary clocks

Exclude ADJ_TAI, leap seconds and PPS functionality as they make no sense
in the context of auxiliary clocks and provide a time stamp based on the
actual clock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183758.253203783@linutronix.de

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 0de61315b40c3ce69c8d3ec8c3bd5c42c3494257..6770544f8c0e568c6f0ab904b690616916630044 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -58,6 +58,17 @@ static struct tk_data timekeeper_data[TIMEKEEPERS_MAX];
 /* The core timekeeper */
 #define tk_core                (timekeeper_data[TIMEKEEPER_CORE])
 
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+static inline bool tk_get_aux_ts64(unsigned int tkid, struct timespec64 *ts)
+{
+       return ktime_get_aux_ts64(CLOCK_AUX + tkid - TIMEKEEPER_AUX_FIRST, ts);
+}
+#else
+static inline bool tk_get_aux_ts64(unsigned int tkid, struct timespec64 *ts)
+{
+       return false;
+}
+#endif
 
 /* flag for if timekeeping is suspended */
 int __read_mostly timekeeping_suspended;
@@ -2508,7 +2519,7 @@ ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
 /*
  * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
  */
-static int timekeeping_validate_timex(const struct __kernel_timex *txc)
+static int timekeeping_validate_timex(const struct __kernel_timex *txc, bool aux_clock)
 {
        if (txc->modes & ADJ_ADJTIME) {
                /* singleshot must not be used with any other mode bits */
@@ -2567,6 +2578,20 @@ static int timekeeping_validate_timex(const struct __kernel_timex *txc)
                        return -EINVAL;
        }
 
+       if (aux_clock) {
+               /* Auxiliary clocks are similar to TAI and do not have leap seconds */
+               if (txc->status & (STA_INS | STA_DEL))
+                       return -EINVAL;
+
+               /* No TAI offset setting */
+               if (txc->modes & ADJ_TAI)
+                       return -EINVAL;
+
+               /* No PPS support either */
+               if (txc->status & (STA_PPSFREQ | STA_PPSTIME))
+                       return -EINVAL;
+       }
+
        return 0;
 }
 
@@ -2595,17 +2620,22 @@ static int __do_adjtimex(struct tk_data *tkd, struct __kernel_timex *txc,
                         struct adjtimex_result *result)
 {
        struct timekeeper *tks = &tkd->shadow_timekeeper;
+       bool aux_clock = !timekeeper_is_core_tk(tks);
        struct timespec64 ts;
        s32 orig_tai, tai;
        int ret;
 
        /* Validate the data before disabling interrupts */
-       ret = timekeeping_validate_timex(txc);
+       ret = timekeeping_validate_timex(txc, aux_clock);
        if (ret)
                return ret;
        add_device_randomness(txc, sizeof(*txc));
 
-       ktime_get_real_ts64(&ts);
+       if (!aux_clock)
+               ktime_get_real_ts64(&ts);
+       else
+               tk_get_aux_ts64(tkd->timekeeper.id, &ts);
+
        add_device_randomness(&ts, sizeof(ts));
 
        guard(raw_spinlock_irqsave)(&tkd->lock);