coreboot-kgpe-d16/src/lib/thread.c

375 lines
8.2 KiB
C

/*
* This file is part of the coreboot project.
*
*
* 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; version 2 of the License.
*
* 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.
*/
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <arch/cpu.h>
#include <bootstate.h>
#include <console/console.h>
#include <thread.h>
#include <timer.h>
static void idle_thread_init(void);
/* There needs to be at least one thread to run the ramstate state machine. */
#define TOTAL_NUM_THREADS (CONFIG_NUM_THREADS + 1)
/* Storage space for the thread structs .*/
static struct thread all_threads[TOTAL_NUM_THREADS];
/* All runnable (but not running) and free threads are kept on their
* respective lists. */
static struct thread *runnable_threads;
static struct thread *free_threads;
static inline struct cpu_info *thread_cpu_info(const struct thread *t)
{
return (void *)(t->stack_orig);
}
static inline int thread_can_yield(const struct thread *t)
{
return (t != NULL && t->can_yield);
}
/* Assumes current CPU info can switch. */
static inline struct thread *cpu_info_to_thread(const struct cpu_info *ci)
{
return ci->thread;
}
static inline struct thread *current_thread(void)
{
return cpu_info_to_thread(cpu_info());
}
static inline int thread_list_empty(struct thread **list)
{
return *list == NULL;
}
static inline struct thread *pop_thread(struct thread **list)
{
struct thread *t;
t = *list;
*list = t->next;
t->next = NULL;
return t;
}
static inline void push_thread(struct thread **list, struct thread *t)
{
t->next = *list;
*list = t;
}
static inline void push_runnable(struct thread *t)
{
push_thread(&runnable_threads, t);
}
static inline struct thread *pop_runnable(void)
{
return pop_thread(&runnable_threads);
}
static inline struct thread *get_free_thread(void)
{
struct thread *t;
struct cpu_info *ci;
struct cpu_info *new_ci;
if (thread_list_empty(&free_threads))
return NULL;
t = pop_thread(&free_threads);
ci = cpu_info();
/* Initialize the cpu_info structure on the new stack. */
new_ci = thread_cpu_info(t);
*new_ci = *ci;
new_ci->thread = t;
/* Reset the current stack value to the original. */
t->stack_current = t->stack_orig;
return t;
}
static inline void free_thread(struct thread *t)
{
push_thread(&free_threads, t);
}
/* The idle thread is ran whenever there isn't anything else that is runnable.
* It's sole responsibility is to ensure progress is made by running the timer
* callbacks. */
static void idle_thread(void *unused)
{
/* This thread never voluntarily yields. */
thread_prevent_coop();
while (1)
timers_run();
}
static void schedule(struct thread *t)
{
struct thread *current = current_thread();
/* If t is NULL need to find new runnable thread. */
if (t == NULL) {
if (thread_list_empty(&runnable_threads))
die("Runnable thread list is empty!\n");
t = pop_runnable();
} else {
/* current is still runnable. */
push_runnable(current);
}
switch_to_thread(t->stack_current, &current->stack_current);
}
static void terminate_thread(struct thread *t)
{
free_thread(t);
schedule(NULL);
}
static void asmlinkage call_wrapper(void *unused)
{
struct thread *current = current_thread();
current->entry(current->entry_arg);
terminate_thread(current);
}
/* Block the current state transitions until thread is complete. */
static void asmlinkage call_wrapper_block_current(void *unused)
{
struct thread *current = current_thread();
boot_state_current_block();
current->entry(current->entry_arg);
boot_state_current_unblock();
terminate_thread(current);
}
struct block_boot_state {
boot_state_t state;
boot_state_sequence_t seq;
};
/* Block the provided state until thread is complete. */
static void asmlinkage call_wrapper_block_state(void *arg)
{
struct block_boot_state *bbs = arg;
struct thread *current = current_thread();
boot_state_block(bbs->state, bbs->seq);
current->entry(current->entry_arg);
boot_state_unblock(bbs->state, bbs->seq);
terminate_thread(current);
}
/* Prepare a thread so that it starts by executing thread_entry(thread_arg).
* Within thread_entry() it will call func(arg). */
static void prepare_thread(struct thread *t, void *func, void *arg,
asmlinkage void (*thread_entry)(void *),
void *thread_arg)
{
/* Stash the function and argument to run. */
t->entry = func;
t->entry_arg = arg;
/* All new threads can yield by default. */
t->can_yield = 1;
arch_prepare_thread(t, thread_entry, thread_arg);
}
static void thread_resume_from_timeout(struct timeout_callback *tocb)
{
struct thread *to;
to = tocb->priv;
schedule(to);
}
static void idle_thread_init(void)
{
struct thread *t;
t = get_free_thread();
if (t == NULL)
die("No threads available for idle thread!\n");
/* Queue idle thread to run once all other threads have yielded. */
prepare_thread(t, idle_thread, NULL, call_wrapper, NULL);
push_runnable(t);
/* Mark the currently executing thread to cooperate. */
thread_cooperate();
}
/* Don't inline this function so the timeout_callback won't have its storage
* space on the stack cleaned up before the call to schedule(). */
static int __attribute__((noinline))
thread_yield_timed_callback(struct timeout_callback *tocb,
unsigned int microsecs)
{
tocb->priv = current_thread();
tocb->callback = thread_resume_from_timeout;
if (timer_sched_callback(tocb, microsecs))
return -1;
/* The timer callback will wake up the current thread. */
schedule(NULL);
return 0;
}
static void *thread_alloc_space(struct thread *t, size_t bytes)
{
/* Allocate the amount of space on the stack keeping the stack
* aligned to the pointer size. */
t->stack_current -= ALIGN_UP(bytes, sizeof(uintptr_t));
return (void *)t->stack_current;
}
void threads_initialize(void)
{
int i;
struct thread *t;
u8 *stack_top;
struct cpu_info *ci;
u8 *thread_stacks;
thread_stacks = arch_get_thread_stackbase();
/* Initialize the BSP thread first. The cpu_info structure is assumed
* to be just under the top of the stack. */
t = &all_threads[0];
ci = cpu_info();
ci->thread = t;
t->stack_orig = (uintptr_t)ci;
t->id = 0;
stack_top = &thread_stacks[CONFIG_STACK_SIZE] - sizeof(struct cpu_info);
for (i = 1; i < TOTAL_NUM_THREADS; i++) {
t = &all_threads[i];
t->stack_orig = (uintptr_t)stack_top;
t->id = i;
stack_top += CONFIG_STACK_SIZE;
free_thread(t);
}
idle_thread_init();
}
int thread_run(void (*func)(void *), void *arg)
{
struct thread *current;
struct thread *t;
current = current_thread();
if (!thread_can_yield(current)) {
printk(BIOS_ERR,
"thread_run() called from non-yielding context!\n");
return -1;
}
t = get_free_thread();
if (t == NULL) {
printk(BIOS_ERR, "thread_run() No more threads!\n");
return -1;
}
prepare_thread(t, func, arg, call_wrapper_block_current, NULL);
schedule(t);
return 0;
}
int thread_run_until(void (*func)(void *), void *arg,
boot_state_t state, boot_state_sequence_t seq)
{
struct thread *current;
struct thread *t;
struct block_boot_state *bbs;
current = current_thread();
if (!thread_can_yield(current)) {
printk(BIOS_ERR,
"thread_run() called from non-yielding context!\n");
return -1;
}
t = get_free_thread();
if (t == NULL) {
printk(BIOS_ERR, "thread_run() No more threads!\n");
return -1;
}
bbs = thread_alloc_space(t, sizeof(*bbs));
bbs->state = state;
bbs->seq = seq;
prepare_thread(t, func, arg, call_wrapper_block_state, bbs);
schedule(t);
return 0;
}
int thread_yield_microseconds(unsigned int microsecs)
{
struct thread *current;
struct timeout_callback tocb;
current = current_thread();
if (!thread_can_yield(current))
return -1;
if (thread_yield_timed_callback(&tocb, microsecs))
return -1;
return 0;
}
void thread_cooperate(void)
{
struct thread *current;
current = current_thread();
if (current != NULL)
current->can_yield = 1;
}
void thread_prevent_coop(void)
{
struct thread *current;
current = current_thread();
if (current != NULL)
current->can_yield = 0;
}