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/*
* Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Hyra nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/sched.h>
#include <sys/schedvar.h>
#include <sys/sched_state.h>
#include <sys/types.h>
#include <sys/timer.h>
#include <sys/cdefs.h>
#include <sys/spinlock.h>
#include <vm/dynalloc.h>
#include <assert.h>
#include <string.h>
/*
* Thread ready queue - all threads ready to be
* scheduled should be added to this queue.
*/
static TAILQ_HEAD(, proc) td_queue;
static size_t nthread = 0;
/*
* Thread queue lock - all operations to `td_queue'
* must be done with this lock acquired.
*/
static struct spinlock tdq_lock = {0};
/* In sys/<machine>/<machine>/switch.S */
void __sched_switch_to(struct trapframe *tf);
static inline void
sched_oneshot(void)
{
struct timer timer;
tmrr_status_t tmr_status;
tmr_status = req_timer(TIMER_SCHED, &timer);
__assert(tmr_status == TMRR_SUCCESS);
timer.oneshot_us(DEFAULT_TIMESLICE_USEC);
}
/*
* Push a thread into the thread ready queue
* allowing it to be eventually dequeued
* and ran.
*/
static void
sched_enqueue_td(struct proc *td)
{
/* Sanity check */
if (td == NULL)
return;
spinlock_acquire(&tdq_lock);
td->pid = nthread++;
TAILQ_INSERT_TAIL(&td_queue, td, link);
spinlock_release(&tdq_lock);
}
/*
* Dequeue the first thread in the thread ready
* queue.
*/
static struct proc *
sched_dequeue_td(void)
{
struct proc *td = NULL;
spinlock_acquire(&tdq_lock);
if (TAILQ_EMPTY(&td_queue)) {
goto done;
}
td = TAILQ_FIRST(&td_queue);
TAILQ_REMOVE(&td_queue, td, link);
done:
spinlock_release(&tdq_lock);
return td;
}
/*
* Processor awaiting tasks to be assigned will be here spinning.
*/
__noreturn static void
sched_enter(void)
{
sched_oneshot();
for (;;) {
hint_spinwait();
}
}
static struct proc *
sched_create_td(uintptr_t rip)
{
const size_t STACK_SIZE = 0x100000; /* 1 MiB */
struct proc *td;
void *stack;
struct trapframe *tf;
tf = dynalloc(sizeof(struct trapframe));
if (tf == NULL) {
return NULL;
}
stack = dynalloc(STACK_SIZE);
if (stack == NULL) {
dynfree(tf);
return NULL;
}
td = dynalloc(sizeof(struct proc));
if (td == NULL) {
dynfree(tf);
dynfree(stack);
return NULL;
}
memset(tf, 0, sizeof(struct trapframe));
memset(stack, 0, STACK_SIZE);
/* Setup process itself */
td->pid = 0; /* Don't assign PID until enqueued */
td->cpu = NULL; /* Not yet assigned a core */
td->tf = tf;
/* Setup trapframe */
init_frame(tf, rip, (uintptr_t)stack + STACK_SIZE - 1);
return td;
}
/*
* Thread context switch routine
*/
void
sched_context_switch(struct trapframe *tf)
{
struct cpu_info *ci = this_cpu();
struct sched_state *state = &ci->sched_state;
struct proc *td, *next_td;
/*
* If we only have one thread or even no threads, there is
* no point in preempting.
*/
if (nthread == 1 || nthread == 0) {
goto done;
} else if ((next_td = sched_dequeue_td()) == NULL) {
/* Empty */
goto done;
}
if (state->td != NULL) {
/* Save our trapframe */
td = state->td;
memcpy(td->tf, tf, sizeof(struct trapframe));
}
/* Copy to stack */
memcpy(tf, next_td->tf, sizeof(struct trapframe));
td = state->td;
state->td = next_td;
if (td != NULL) {
sched_enqueue_td(td);
}
done:
sched_oneshot();
}
void
sched_init(void)
{
TAILQ_INIT(&td_queue);
/*
* TODO: Create init with sched_create_td()
* and enqueue with sched_enqueue_td()
*/
(void)sched_create_td;
(void)sched_enqueue_td;
}
/*
* Setup scheduler related things and enqueue AP.
*/
void
sched_init_processor(struct cpu_info *ci)
{
struct sched_state *sched_state = &ci->sched_state;
(void)sched_state; /* TODO */
sched_enter();
__builtin_unreachable();
}
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