X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvppinfra%2Ftime.c;h=d647e670dad52cd5be34d67dfc5c751f7b0cfa7c;hb=df32bc4dee0cfe514a8fca5085ea555211521387;hp=2bdb9da4b3941fc1240e336c444b32ee9c1cc401;hpb=7cd468a3d7dee7d6c92f69a0bb7061ae208ec727;p=vpp.git

diff --git a/src/vppinfra/time.c b/src/vppinfra/time.c
index 2bdb9da4b39..d647e670dad 100644
--- a/src/vppinfra/time.c
+++ b/src/vppinfra/time.c
@@ -91,7 +91,7 @@ clock_frequency_from_proc_filesystem (void)
   if (fd < 0)
     return cpu_freq;
 
-  unformat_init_unix_file (&input, fd);
+  unformat_init_clib_file (&input, fd);
 
   ppc_timebase = 0;
   while (unformat_check_input (&input) != UNFORMAT_END_OF_INPUT)
@@ -130,7 +130,7 @@ clock_frequency_from_sys_filesystem (void)
   if (fd < 0)
     goto done;
 
-  unformat_init_unix_file (&input, fd);
+  unformat_init_clib_file (&input, fd);
   unformat (&input, "%f", &cpu_freq);
   cpu_freq *= 1e3;		/* measured in kHz */
   unformat_free (&input);
@@ -142,6 +142,15 @@ done:
 f64
 os_cpu_clock_frequency (void)
 {
+#if defined (__aarch64__)
+  /* The system counter increments at a fixed frequency. It is distributed
+   * to each core which has registers for reading the current counter value
+   * as well as the clock frequency. The system counter is not clocked at
+   * the same frequency as the core. */
+  u64 hz;
+  asm volatile ("mrs %0, cntfrq_el0":"=r" (hz));
+  return (f64) hz;
+#endif
   f64 cpu_freq;
 
   if (clib_cpu_supports_invariant_tsc ())
@@ -188,6 +197,7 @@ clib_time_verify_frequency (clib_time_t * c)
   f64 dtr = now_reference - c->last_verify_reference_time;
   f64 dtr_max;
   u64 dtc = c->last_cpu_time - c->last_verify_cpu_time;
+  f64 new_clocks_per_second, delta;
   f64 round_units = 100e5;
 
   c->last_verify_cpu_time = c->last_cpu_time;
@@ -208,6 +218,25 @@ clib_time_verify_frequency (clib_time_t * c)
       return;
     }
 
+  /*
+   * Reject large frequency changes, another consequence of
+   * system clock changes particularly with old kernels.
+   */
+  new_clocks_per_second =
+    flt_round_nearest ((f64) dtc / (dtr * round_units)) * round_units;
+
+  delta = new_clocks_per_second - c->clocks_per_second;
+  if (delta < 0.0)
+    delta = -delta;
+
+  if (PREDICT_FALSE ((delta / c->clocks_per_second) > .01))
+    {
+      clib_warning ("Rejecting large frequency change of %.2f%%",
+		    (delta / c->clocks_per_second) * 100.0);
+      c->log2_clocks_per_frequency_verify = c->log2_clocks_per_second;
+      return;
+    }
+
   c->clocks_per_second =
     flt_round_nearest ((f64) dtc / (dtr * round_units)) * round_units;
   c->seconds_per_clock = 1 / c->clocks_per_second;