/*

 * Support for initialising programs in new tasks and threads.

 *

 * Copyright (C) 2022, 2023 Paul Boddie <paul@boddie.org.uk>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License as

 * published by the Free Software Foundation; either version 2 of

 * the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor,

 * Boston, MA  02110-1301, USA

 */

#include <l4/sys/err.h>

#include <l4/sys/scheduler.h>

#include <exec/process.h>

#include <ipc/cap_alloc.h>

#include <ipc/map.h>

#include <mem/memory_utils.h>

/* Obtain a flexpage defining the UTCB area location and size in a new task. */

static l4_fpage_t get_utcb_fpage(unsigned int page, unsigned int pages)

{

  /* UTCB location and size. */

  int utcb_log2size = page_order(Default_max_threads * L4_UTCB_OFFSET);

  /* Round up to at least one page. */

  if (utcb_log2size < L4_PAGESHIFT)

    utcb_log2size = L4_PAGESHIFT;

  utcb_log2size = page_order(pages * (1UL << utcb_log2size));

  return l4_fpage(Utcb_area_start + page * (1UL << utcb_log2size), utcb_log2size, 0);

}

/* Initialise a new process, this being an abstraction for a new task with some

   threads. */

Process::Process()

{

  reset();

}

void Process::reset()

{

  _thread_number = 0;

  /* Populate the common initial environment for the threads. */

  _env.factory          = L4_BASE_FACTORY_CAP;

  _env.log              = L4_BASE_LOG_CAP;

  _env.scheduler        = L4_BASE_SCHEDULER_CAP;

  _env.mem_alloc        = L4_EXEC_MA_CAP;

  _env.parent           = L4_EXEC_PARENT_CAP;

  /* Capability details that are updated for each thread. Note that the region

     mapper is redefined, but it would traditionally employ the given index. */

  _env.main_thread      = L4_BASE_THREAD_CAP;

  _env.rm               = L4_EXEC_RM_CAP;

  _env.first_free_cap   = L4_EXEC_FIRST_FREE_CAP_INDEX;

  /* Populate auxiliary information. */

  _aux.kip_ds           = L4_EXEC_KIP_CAP;

  _aux.dbg_lvl          = 0;

  _aux.ldr_flags        = 0;

}

/* Capability index allocation. */

l4_cap_idx_t Process::allocate_cap()

{

  return (_env.first_free_cap++ << L4_CAP_SHIFT);

}

/* Task and thread initialisation. */

long Process::create_task(unsigned int threads)

{

  /* Reset the process if it has already been used. */

  if (_thread_number)

    reset();

  _task = ipc_cap_alloc();

  if (l4_is_invalid_cap(_task))

    return -L4_ENOMEM;

  return l4_error(l4_factory_create_task(l4re_env()->factory, _task, get_utcb_fpage(0, threads)));

}

long Process::create_thread(l4_cap_idx_t *thread)

{

  *thread = ipc_cap_alloc();

  if (l4_is_invalid_cap(*thread))

    return -L4_ENOMEM;

  return l4_error(l4_factory_create_thread(l4re_env()->factory, *thread));

}

/* Configure the task environment. */

long Process::configure_task(l4_cap_idx_t *task, l4_cap_idx_t *mapped_task, unsigned int threads)

{

  long err = create_task(threads);

  if (err)

    return err;

  /* Map the KIP into the task. */

  l4_addr_t kip_start = (l4_addr_t) l4re_kip();

  err = l4_error(l4_task_map(_task, L4RE_THIS_TASK_CAP,

                             l4_fpage(kip_start, L4_PAGESHIFT, L4_FPAGE_RX),

                             kip_start));

  if (err)

    return err;

  /* Define capability mappings for the new task. */

  struct ipc_mapped_cap mapped_caps[] = {

    {L4_BASE_TASK_CAP,  _task,                  L4_CAP_FPAGE_RWS, 0},

    {_env.factory,      l4re_env()->factory,    L4_CAP_FPAGE_RWS, 0},

    {_env.log,          l4re_env()->log,        L4_CAP_FPAGE_RWS, 0},

    {_env.scheduler,    l4re_env()->scheduler,  L4_CAP_FPAGE_RWS, 0},

    {_env.mem_alloc,    l4re_env()->mem_alloc,  L4_CAP_FPAGE_RWS, 0},

    {0,                 L4_INVALID_CAP,         0,                0},

    };

  /* Return the capability details for the task. */

  *task = _task;

  *mapped_task = L4_BASE_TASK_CAP;

  return map_capabilities(mapped_caps, false);

}

/* Configure the thread environment, employing the given capability for the

   region mapper, returning its capability details in the new task. */

long Process::configure_thread(l4_cap_idx_t rm, l4_cap_idx_t *mapped_rm)

{

  /* Employ a distinct region mapper for each thread's environment, this acting

     as pager. */

  if ((mapped_rm != NULL) && l4_is_valid_cap(*mapped_rm))

  {

    _env.rm = *mapped_rm;

    return L4_EOK;

  }

  else

  {

    _env.rm = allocate_cap();

    *mapped_rm = _env.rm;

    return ipc_map_capability(_task, (struct ipc_mapped_cap) {_env.rm, rm, L4_CAP_FPAGE_RWS, 0});

  }

}

/* Set the parent of the new thread. */

long Process::set_parent(l4_cap_idx_t parent, l4_cap_idx_t *mapped_parent)

{

  *mapped_parent = _env.parent;

  return ipc_map_capability(_task, (struct ipc_mapped_cap) {_env.parent, parent, L4_CAP_FPAGE_RWS, 0});

}

/* Map capabilities into the task, counting them if indicated. If capability

   indexes are obtained using the allocate_cap method, then they do not need to

   be counted again. */

long Process::map_capabilities(struct ipc_mapped_cap mapped_caps[],

                               bool to_count)

{

  unsigned int num_mapped_caps;

  long err = ipc_map_capabilities(_task, mapped_caps, to_count ? &num_mapped_caps : NULL);

  if (to_count)

    _env.first_free_cap += num_mapped_caps;

  return err;

}

/* Create, initialise and start a thread. */

long Process::thread_start(l4_addr_t program_start, Stack &st,

                           l4_cap_idx_t *thread, l4_cap_idx_t *mapped_thread)

{

  long err;

  err = create_thread(thread);

  if (err)

    return err;

  /* Obtain UTCB area details for the thread. */

  l4_fpage_t utcb_fpage = get_utcb_fpage(_thread_number, 1);

  _env.utcb_area       = utcb_fpage;

  _env.first_free_utcb = l4_fpage_memaddr(utcb_fpage) + L4_UTCB_OFFSET;

  /* Initialise the thread with pager, UTCB and task details. */

  l4_thread_control_start();

  l4_thread_control_pager(_env.rm);

  l4_thread_control_exc_handler(_env.rm);

  l4_thread_control_bind((l4_utcb_t *) l4_fpage_memaddr(_env.utcb_area), _task);

  err = l4_error(l4_thread_control_commit(*thread));

  if (err)

  {

    ipc_cap_free(*thread);

    return err;

  }

  /* Map the thread capability to the task using a distinct capability index. */

  _env.main_thread = allocate_cap();

  ipc_map_capability(_task, (struct ipc_mapped_cap) {_env.main_thread, *thread, L4_CAP_FPAGE_RWS, 0});

  /* Populate the initial environment in the thread. */

  st.set_l4re_aux(&_aux);

  st.set_l4re_env(&_env);

  /* Reserve some extra space for capabilities used by this thread.

     NOTE: Surely the capability allocator should be able to avoid conflicts,

           but concurrency issues have been observed before, leading to various

           measures in libipc. */

  _env.first_free_cap += 0x20;

  /* Set the start details. */

  err = l4_error(l4_thread_ex_regs(*thread, program_start, st.start_address(), 0));

  if (err)

    return err;

  /* Select a new thread. */

  _thread_number++;

  /* Start the thread. */

  l4_sched_param_t sp = l4_sched_param(L4RE_MAIN_THREAD_PRIO);

  *mapped_thread = _env.main_thread;

  return l4_error(l4_scheduler_run_thread(l4re_env()->scheduler, *thread, &sp));

}

/* vim: tabstop=2 expandtab shiftwidth=2

*/