zircon/kernel/top/init.cc

// Copyright 2016 The Fuchsia Authors
// Copyright (c) 2013 Travis Geiselbrecht
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

/*
 * Global init hook mechanism. Allows code anywhere in the system to define
 * a init hook that is called at increasing init levels as the system is
 * initialized.
 */
#include "lk/init.h"

#include <assert.h>
#include <debug.h>
#include <trace.h>
#include <zircon/compiler.h>

#include <arch/ops.h>

#define LOCAL_TRACE 0

extern const struct lk_init_struct __start_lk_init[];
extern const struct lk_init_struct __stop_lk_init[];

void lk_init_level(enum lk_init_flags required_flag, uint start_level, uint stop_level) {
  LTRACEF("flags %#x, start_level %#x, stop_level %#x\n", (uint)required_flag, start_level,
          stop_level);

  ASSERT(start_level > 0);
  uint last_called_level = start_level - 1;
  const struct lk_init_struct* last = NULL;
  for (;;) {
    /* search for the lowest uncalled hook to call */
    LTRACEF("last %p, last_called_level %#x\n", last, last_called_level);

    const struct lk_init_struct* found = NULL;
    bool seen_last = false;
    for (const struct lk_init_struct* ptr = __start_lk_init; ptr != __stop_lk_init; ptr++) {
      LTRACEF("looking at %p (%s) level %#x, flags %#x, seen_last %d\n", ptr, ptr->name, ptr->level,
              ptr->flags, seen_last);

      if (ptr == last)
        seen_last = true;

      /* reject the easy ones */
      if (!(ptr->flags & required_flag))
        continue;
      if (ptr->level > stop_level)
        continue;
      if (ptr->level < last_called_level)
        continue;
      if (found && found->level <= ptr->level)
        continue;

      /* keep the lowest one we haven't called yet */
      if (ptr->level >= start_level && ptr->level > last_called_level) {
        found = ptr;
        continue;
      }

      /* if we're at the same level as the last one we called and we've
       * already passed over it this time around, we can mark this one
       * and early terminate the loop.
       */
      if (ptr->level == last_called_level && ptr != last && seen_last) {
        found = ptr;
        break;
      }
    }

    if (!found)
      break;

    dprintf(INFO, "INIT: cpu %u, calling hook %p (%s) at level %#x, flags %#x\n", arch_curr_cpu_num(),
           found->hook, found->name, found->level, found->flags);

    found->hook(found->level);
    last_called_level = found->level;
    last = found;
  }
}