/* Copyright (C) 2004,2005 David Decotigny
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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.
*/
#include <sos/physmem.h>
#include <sos/kmem_slab.h>
#include <sos/kmalloc.h>
#include <sos/klibc.h>
#include <sos/list.h>
#include <sos/assert.h>
#include <hwcore/irq.h>
#include "thread.h"
/**
* The size of the stack of a kernel thread
*/
#define SOS_THREAD_KERNEL_STACK_SIZE (1*SOS_PAGE_SIZE)
/**
* The identifier of the thread currently running on CPU.
*
* We only support a SINGLE processor, ie a SINGLE thread
* running at any time in the system. This greatly simplifies the
* implementation of the system, since we don't have to complicate
* things in order to retrieve the identifier of the threads running
* on the CPU. On multiprocessor systems the current_thread below is
* an array indexed by the id of the CPU, so that the challenge is to
* retrieve the identifier of the CPU. This is usually done based on
* the stack address (Linux implementation) or on some form of TLS
* ("Thread Local Storage": can be implemented by way of LDTs for the
* processes, accessed through the fs or gs registers).
*/
static volatile struct sos_thread *current_thread = NULL;
/*
* The list of threads currently in the system.
*
* @note We could have used current_thread for that...
*/
static struct sos_thread *thread_list = NULL;
/**
* The Cache of thread structures
*/
static struct sos_kslab_cache *cache_thread;
struct sos_thread *sos_thread_get_current()
{
SOS_ASSERT_FATAL(current_thread->state == SOS_THR_RUNNING);
return (struct sos_thread*)current_thread;
}
inline static sos_ret_t _set_current(struct sos_thread *thr)
{
SOS_ASSERT_FATAL(thr->state == SOS_THR_READY);
current_thread = thr;
current_thread->state = SOS_THR_RUNNING;
return SOS_OK;
}
sos_ret_t sos_thread_subsystem_setup(sos_vaddr_t init_thread_stack_base_addr,
sos_size_t init_thread_stack_size)
{
struct sos_thread *myself;
/* Allocate the cache of threads */
cache_thread = sos_kmem_cache_create("thread",
sizeof(struct sos_thread),
2,
0,
SOS_KSLAB_CREATE_MAP
| SOS_KSLAB_CREATE_ZERO);
if (! cache_thread)
return -SOS_ENOMEM;
/* Allocate a new thread structure for the current running thread */
myself = (struct sos_thread*) sos_kmem_cache_alloc(cache_thread,
SOS_KSLAB_ALLOC_ATOMIC);
if (! myself)
return -SOS_ENOMEM;
/* Initialize the thread attributes */
strzcpy(myself->name, "[kinit]", SOS_THR_MAX_NAMELEN);
myself->state = SOS_THR_CREATED;
myself->kernel_stack_base_addr = init_thread_stack_base_addr;
myself->kernel_stack_size = init_thread_stack_size;
/* Do some stack poisoning on the bottom of the stack, if needed */
sos_cpu_state_prepare_detect_kernel_stack_overflow(myself->cpu_state,
myself->kernel_stack_base_addr,
myself->kernel_stack_size);
/* Add the thread in the global list */
list_singleton_named(thread_list, myself, gbl_prev, gbl_next);
/* Ok, now pretend that the running thread is ourselves */
myself->state = SOS_THR_READY;
_set_current(myself);
return SOS_OK;
}
struct sos_thread *
sos_create_kernel_thread(const char *name,
sos_kernel_thread_start_routine_t start_func,
void *start_arg)
{
__label__ undo_creation;
sos_ui32_t flags;
struct sos_thread *new_thread;
if (! start_func)
return NULL;
/* Allocate a new thread structure for the current running thread */
new_thread
= (struct sos_thread*) sos_kmem_cache_alloc(cache_thread,
SOS_KSLAB_ALLOC_ATOMIC);
if (! new_thread)
return NULL;
/* Initialize the thread attributes */
strzcpy(new_thread->name, ((name)?name:"[NONAME]"), SOS_THR_MAX_NAMELEN);
new_thread->state = SOS_THR_CREATED;
/* Allocate the stack for the new thread */
new_thread->kernel_stack_base_addr = sos_kmalloc(SOS_THREAD_KERNEL_STACK_SIZE, 0);
new_thread->kernel_stack_size = SOS_THREAD_KERNEL_STACK_SIZE;
if (! new_thread->kernel_stack_base_addr)
goto undo_creation;
/* Initialize the CPU context of the new thread */
if (SOS_OK
!= sos_cpu_kstate_init(& new_thread->cpu_state,
(sos_cpu_kstate_function_arg1_t*) start_func,
(sos_ui32_t) start_arg,
new_thread->kernel_stack_base_addr,
new_thread->kernel_stack_size,
(sos_cpu_kstate_function_arg1_t*) sos_thread_exit,
(sos_ui32_t) NULL))
goto undo_creation;
/* Add the thread in the global list */
sos_disable_IRQs(flags);
list_add_tail_named(thread_list, new_thread, gbl_prev, gbl_next);
sos_restore_IRQs(flags);
/* Mark the thread ready */
if (SOS_OK != sos_sched_set_ready(new_thread))
goto undo_creation;
/* Normal non-erroneous end of function */
return new_thread;
undo_creation:
if (new_thread->kernel_stack_base_addr)
sos_kfree((sos_vaddr_t) new_thread->kernel_stack_base_addr);
sos_kmem_cache_free((sos_vaddr_t) new_thread);
return NULL;
}
/** Function called after thr has terminated. Called from inside the context
of another thread, interrupts disabled */
static void delete_thread(struct sos_thread *thr)
{
sos_ui32_t flags;
sos_disable_IRQs(flags);
list_delete_named(thread_list, thr, gbl_prev, gbl_next);
sos_restore_IRQs(flags);
sos_kfree((sos_vaddr_t) thr->kernel_stack_base_addr);
memset(thr, 0x0, sizeof(struct sos_thread));
sos_kmem_cache_free((sos_vaddr_t) thr);
}
void sos_thread_exit()
{
sos_ui32_t flags;
struct sos_thread *myself, *next_thread;
/* Interrupt handlers are NOT allowed to exit the current thread ! */
SOS_ASSERT_FATAL(! sos_servicing_irq());
myself = sos_thread_get_current();
/* Refuse to end the current executing thread if it still holds a
resource ! */
SOS_ASSERT_FATAL(list_is_empty_named(myself->kwaitq_list,
prev_entry_for_thread,
next_entry_for_thread));
/* Prepare to run the next thread */
sos_disable_IRQs(flags);
myself->state = SOS_THR_ZOMBIE;
next_thread = sos_reschedule(myself, FALSE);
/* Make sure that the next_thread is valid */
sos_cpu_state_detect_kernel_stack_overflow(next_thread->cpu_state,
next_thread->kernel_stack_base_addr,
next_thread->kernel_stack_size);
/* No need for sos_restore_IRQs() here because the IRQ flag will be
restored to that of the next thread upon context switch */
/* Immediate switch to next thread */
_set_current(next_thread);
sos_cpu_context_exit_to(next_thread->cpu_state,
(sos_cpu_kstate_function_arg1_t*) delete_thread,
(sos_ui32_t) myself);
}
sos_thread_state_t sos_thread_get_state(struct sos_thread *thr)
{
if (! thr)
thr = (struct sos_thread*)current_thread;
return thr->state;
}
typedef enum { YIELD_MYSELF, BLOCK_MYSELF } switch_type_t;
/**
* Helper function to initiate a context switch in case the current
* thread becomes blocked, waiting for a timeout, or calls yield.
*/
static sos_ret_t _switch_to_next_thread(switch_type_t operation)
{
struct sos_thread *myself, *next_thread;
SOS_ASSERT_FATAL(current_thread->state == SOS_THR_RUNNING);
/* Interrupt handlers are NOT allowed to block ! */
SOS_ASSERT_FATAL(! sos_servicing_irq());
myself = (struct sos_thread*)current_thread;
/* Make sure that if we are to be marked "BLOCKED", we have any
reason of effectively being blocked */
if (BLOCK_MYSELF == operation)
{
myself->state = SOS_THR_BLOCKED;
}
/* Identify the next thread */
next_thread = sos_reschedule(myself, YIELD_MYSELF == operation);
/* Avoid context switch if the context does not change */
if (myself != next_thread)
{
/* Sanity checks for the next thread */
sos_cpu_state_detect_kernel_stack_overflow(next_thread->cpu_state,
next_thread->kernel_stack_base_addr,
next_thread->kernel_stack_size);
/*
* Actual CPU context switch
*/
_set_current(next_thread);
sos_cpu_context_switch(& myself->cpu_state, next_thread->cpu_state);
/* Back here ! */
SOS_ASSERT_FATAL(current_thread == myself);
SOS_ASSERT_FATAL(current_thread->state == SOS_THR_RUNNING);
}
else
{
/* No context switch but still update ID of current thread */
_set_current(next_thread);
}
return SOS_OK;
}
sos_ret_t sos_thread_yield()
{
sos_ui32_t flags;
sos_ret_t retval;
sos_disable_IRQs(flags);
retval = _switch_to_next_thread(YIELD_MYSELF);
sos_restore_IRQs(flags);
return retval;
}
/**
* Internal sleep timeout management
*/
struct sleep_timeout_params
{
struct sos_thread *thread_to_wakeup;
sos_bool_t timeout_triggered;
};
/**
* Callback called when a timeout happened
*/
static void sleep_timeout(struct sos_timeout_action *act)
{
struct sleep_timeout_params *sleep_timeout_params
= (struct sleep_timeout_params*) act->routine_data;
/* Signal that we have been woken up by the timeout */
sleep_timeout_params->timeout_triggered = TRUE;
/* Mark the thread ready */
SOS_ASSERT_FATAL(SOS_OK ==
sos_thread_force_unblock(sleep_timeout_params
->thread_to_wakeup));
}
sos_ret_t sos_thread_sleep(struct sos_time *timeout)
{
sos_ui32_t flags;
struct sleep_timeout_params sleep_timeout_params;
struct sos_timeout_action timeout_action;
sos_ret_t retval;
/* Block forever if no timeout is given */
if (NULL == timeout)
{
sos_disable_IRQs(flags);
retval = _switch_to_next_thread(BLOCK_MYSELF);
sos_restore_IRQs(flags);
return retval;
}
/* Initialize the timeout action */
sos_time_init_action(& timeout_action);
/* Prepare parameters used by the sleep timeout callback */
sleep_timeout_params.thread_to_wakeup
= (struct sos_thread*)current_thread;
sleep_timeout_params.timeout_triggered = FALSE;
sos_disable_IRQs(flags);
/* Now program the timeout ! */
SOS_ASSERT_FATAL(SOS_OK ==
sos_time_register_action_relative(& timeout_action,
timeout,
sleep_timeout,
& sleep_timeout_params));
/* Prepare to block: wait for sleep_timeout() to wakeup us in the
timeout kwaitq, or for someone to wake us up in any other
waitq */
retval = _switch_to_next_thread(BLOCK_MYSELF);
/* Unblocked by something ! */
/* Unblocked by timeout ? */
if (sleep_timeout_params.timeout_triggered)
{
/* Yes */
SOS_ASSERT_FATAL(sos_time_is_zero(& timeout_action.timeout));
retval = SOS_OK;
}
else
{
/* No: We have probably been woken up while in some other
kwaitq */
SOS_ASSERT_FATAL(SOS_OK == sos_time_unregister_action(& timeout_action));
retval = -SOS_EINTR;
}
sos_restore_IRQs(flags);
/* Update the remaining timeout */
memcpy(timeout, & timeout_action.timeout, sizeof(struct sos_time));
return retval;
}
sos_ret_t sos_thread_force_unblock(struct sos_thread *thread)
{
sos_ret_t retval;
sos_ui32_t flags;
if (! thread)
return -SOS_EINVAL;
sos_disable_IRQs(flags);
/* Thread already woken up ? */
retval = SOS_OK;
switch(sos_thread_get_state(thread))
{
case SOS_THR_RUNNING:
case SOS_THR_READY:
/* Do nothing */
break;
case SOS_THR_ZOMBIE:
retval = -SOS_EFATAL;
break;
default:
retval = sos_sched_set_ready(thread);
break;
}
sos_restore_IRQs(flags);
return retval;
}
