src/side.c

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * Copyright 2022 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  */
   5
   6 #include <side/trace.h>
   7 #include "tracer.h"
   8 #include "rcu.h"
   9
  10 /* Top 8 bits reserved for kernel tracer use. */
  11 #define SIDE_EVENT_ENABLED_KERNEL_MASK                  0xFF000000
  12 #define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK       0x80000000
  13
  14 /* Allow 2^24 tracers to be registered on an event. */
  15 #define SIDE_EVENT_ENABLED_USER_MASK                    0x00FFFFFF
  16
  17 struct side_rcu_gp_state rcu_gp;
  18
  19 /*
  20  * Lazy initialization for early use within library constructors.
  21  */
  22 static bool initialized;
  23
  24 static
  25 void side_init(void)
  26         __attribute__((constructor));
  27
  28 const struct side_callback side_empty_callback;
  29
  30 void side_call(const struct side_event_description *desc, const struct side_arg_vec_description *sav_desc)
  31 {
  32         const struct side_callback *side_cb;
  33         unsigned int rcu_period;
  34
  35         if (side_unlikely(!initialized))
  36                 side_init();
  37         if (side_unlikely(desc->flags & SIDE_EVENT_FLAG_VARIADIC)) {
  38                 printf("ERROR: unexpected variadic event description\n");
  39                 abort();
  40         }
  41         if (side_unlikely(*desc->enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
  42                 // TODO: call kernel write.
  43         }
  44         if (side_unlikely(!(*desc->enabled & SIDE_EVENT_ENABLED_USER_MASK)))
  45                 return;
  46
  47         //TODO: replace tracer_call by rcu iteration on list of registered callbacks
  48         tracer_call(desc, sav_desc, NULL);
  49
  50         rcu_period = side_rcu_read_begin(&rcu_gp);
  51         for (side_cb = side_rcu_dereference(desc->callbacks); side_cb->u.call != NULL; side_cb++)
  52                 side_cb->u.call(desc, sav_desc, side_cb->priv);
  53         side_rcu_read_end(&rcu_gp, rcu_period);
  54 }
  55
  56 void side_call_variadic(const struct side_event_description *desc,
  57         const struct side_arg_vec_description *sav_desc,
  58         const struct side_arg_dynamic_event_struct *var_struct)
  59 {
  60         const struct side_callback *side_cb;
  61         unsigned int rcu_period;
  62
  63         if (side_unlikely(!initialized))
  64                 side_init();
  65         if (side_unlikely(*desc->enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
  66                 // TODO: call kernel write.
  67         }
  68         if (side_unlikely(!(*desc->enabled & SIDE_EVENT_ENABLED_USER_MASK)))
  69                 return;
  70
  71         //TODO: replace tracer_call by rcu iteration on list of registered callbacks
  72         tracer_call_variadic(desc, sav_desc, var_struct, NULL);
  73
  74         rcu_period = side_rcu_read_begin(&rcu_gp);
  75         for (side_cb = side_rcu_dereference(desc->callbacks); side_cb->u.call_variadic != NULL; side_cb++)
  76                 side_cb->u.call_variadic(desc, sav_desc, var_struct, side_cb->priv);
  77         side_rcu_read_end(&rcu_gp, rcu_period);
  78 }
  79
  80 void side_init(void)
  81 {
  82         if (initialized)
  83                 return;
  84         side_rcu_gp_init(&rcu_gp);
  85         initialized = true;
  86 }