4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2001, 2004 Develer S.r.l. (http://www.develer.com/)
30 * Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
33 * \brief Simple cooperative multitasking scheduler.
36 * \author Bernie Innocenti <bernie@codewiz.org>
37 * \author Stefano Fedrigo <aleph@develer.com>
43 #include "cfg/cfg_arch.h" // ARCH_EMUL
44 #include "cfg/cfg_kern.h"
45 #include <cfg/macros.h> // ROUND_UP2
46 #include <cfg/module.h>
47 #include <cfg/depend.h> // CONFIG_DEPEND()
50 #include <cpu/types.h>
52 #include <cpu/frame.h>
55 #include <struct/heap.h>
58 #include <string.h> /* memset() */
60 // Check config dependencies
61 CONFIG_DEPEND(CONFIG_KERN_SIGNALS, CONFIG_KERN_SCHED);
62 CONFIG_DEPEND(CONFIG_KERN_SEMAPHORES, CONFIG_KERN_SIGNALS);
63 CONFIG_DEPEND(CONFIG_KERN_MONITOR, CONFIG_KERN_SCHED);
67 * The scheduer tracks ready processes by enqueuing them in the
70 * \note Access to the list must occur while interrupts are disabled.
72 REGISTER List ProcReadyList;
75 * Holds a pointer to the TCB of the currently running process.
77 * \note User applications should use proc_current() to retrieve this value.
79 REGISTER Process *CurrentProcess;
81 #if (ARCH & ARCH_EMUL)
83 * In some hosted environments, we must emulate the stack on the real
84 * process stack to satisfy consistency checks in system libraries and
85 * because some ABIs place trampolines on the stack.
87 * Access to this list must be protected by PROC_ATOMIC().
92 cpu_stack_t proc_stacks[NPROC][(64 * 1024) / sizeof(cpu_stack_t)];
95 /** The main process (the one that executes main()). */
96 struct Process MainProcess;
99 static void proc_init_struct(Process *proc)
101 /* Avoid warning for unused argument. */
104 #if CONFIG_KERN_SIGNALS
123 LIST_INIT(&ProcReadyList);
126 LIST_INIT(&StackFreeList);
127 for (int i = 0; i < NPROC; i++)
128 ADDTAIL(&StackFreeList, (Node *)proc_stacks[i]);
132 * We "promote" the current context into a real process. The only thing we have
133 * to do is create a PCB and make it current. We don't need to setup the stack
134 * pointer because it will be written the first time we switch to another process.
136 proc_init_struct(&MainProcess);
137 CurrentProcess = &MainProcess;
139 #if CONFIG_KERN_MONITOR
141 monitor_add(CurrentProcess, "main");
144 #if CONFIG_KERN_PREEMPT
152 * Create a new process, starting at the provided entry point.
154 * \return Process structure of new created process
155 * if successful, NULL otherwise.
157 struct Process *proc_new_with_name(UNUSED_ARG(const char *, name), void (*entry)(void), iptr_t data, size_t stack_size, cpu_stack_t *stack_base)
160 const size_t PROC_SIZE_WORDS = ROUND_UP2(sizeof(Process), sizeof(cpu_stack_t)) / sizeof(cpu_stack_t);
162 bool free_stack = false;
164 TRACEMSG("name=%s", name);
166 #if (ARCH & ARCH_EMUL)
167 /* Ignore stack provided by caller and use the large enough default instead. */
168 PROC_ATOMIC(stack_base = (cpu_stack_t *)list_remHead(&StackFreeList));
170 stack_size = CONFIG_KERN_MINSTACKSIZE;
171 #elif CONFIG_KERN_HEAP
172 /* Did the caller provide a stack for us? */
175 /* Did the caller specify the desired stack size? */
177 stack_size = CONFIG_KERN_MINSTACKSIZE;
179 /* Allocate stack dinamically */
180 if (!(stack_base = heap_alloc(stack_size)))
186 #else // !ARCH_EMUL && !CONFIG_KERN_HEAP
188 /* Stack must have been provided by the user */
189 ASSERT_VALID_PTR(stack_base);
192 #endif // !ARCH_EMUL && !CONFIG_KERN_HEAP
194 #if CONFIG_KERN_MONITOR
196 * Fill-in the stack with a special marker to help debugging.
197 * On 64bit platforms, CONFIG_KERN_STACKFILLCODE is larger
198 * than an int, so the (int) cast is required to silence the
199 * warning for truncating its size.
201 memset(stack_base, (int)CONFIG_KERN_STACKFILLCODE, stack_size);
204 /* Initialize the process control block */
205 if (CPU_STACK_GROWS_UPWARD)
207 proc = (Process *)stack_base;
208 proc->stack = stack_base + PROC_SIZE_WORDS;
209 if (CPU_SP_ON_EMPTY_SLOT)
214 proc = (Process *)(stack_base + stack_size / sizeof(cpu_stack_t) - PROC_SIZE_WORDS);
215 proc->stack = (cpu_stack_t *)proc;
216 if (CPU_SP_ON_EMPTY_SLOT)
220 proc_init_struct(proc);
221 proc->user_data = data;
223 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR | (ARCH & ARCH_EMUL)
224 proc->stack_base = stack_base;
225 proc->stack_size = stack_size;
228 proc->flags |= PF_FREESTACK;
232 #if CONFIG_KERN_PREEMPT
234 getcontext(&proc->context);
235 proc->context.uc_stack.ss_sp = proc->stack;
236 proc->context.uc_stack.ss_size = stack_size - PROC_SIZE_WORDS - 1;
237 proc->context.uc_link = NULL;
238 makecontext(&proc->context, (void (*)(void))proc_entry, 1, entry);
240 #else // !CONFIG_KERN_PREEMPT
244 /* Initialize process stack frame */
245 CPU_PUSH_CALL_FRAME(proc->stack, proc_exit);
246 CPU_PUSH_CALL_FRAME(proc->stack, entry);
248 /* Push a clean set of CPU registers for asm_switch_context() */
249 for (i = 0; i < CPU_SAVED_REGS_CNT; i++)
250 CPU_PUSH_WORD(proc->stack, CPU_REG_INIT_VALUE(i));
252 #endif // CONFIG_KERN_PREEMPT
254 #if CONFIG_KERN_MONITOR
255 monitor_add(proc, name);
258 /* Add to ready list */
259 ATOMIC(SCHED_ENQUEUE(proc));
265 * Return the name of the specified process.
267 * NULL is a legal argument and will return the name "<NULL>".
269 const char *proc_name(struct Process *proc)
271 #if CONFIG_KERN_MONITOR
272 return proc ? proc->monitor.name : "<NULL>";
279 /// Return the name of the currently running process
280 const char *proc_currentName(void)
282 return proc_name(proc_current());
286 void proc_rename(struct Process *proc, const char *name)
288 #if CONFIG_KERN_MONITOR
289 monitor_rename(proc, name);
291 (void)proc; (void)name;
298 * Change the scheduling priority of a process.
300 * Process piorities are signed ints, whereas a larger integer value means
301 * higher scheduling priority. The default priority for new processes is 0.
302 * The idle process runs with the lowest possible priority: INT_MIN.
304 * A process with a higher priority always preempts lower priority processes.
305 * Processes of equal priority share the CPU time according to a simple
306 * round-robin policy.
308 * As a general rule to maximize responsiveness, compute-bound processes
309 * should be assigned negative priorities and tight, interactive processes
310 * should be assigned positive priorities.
312 * To avoid interfering with system background activities such as input
313 * processing, application processes should remain within the range -10
316 void proc_setPri(struct Process *proc, int pri)
318 if (proc->link.pri == pri)
321 proc->link.pri = pri;
323 if (proc != CurrentProcess)
326 //TODO: re-enqueue process
330 #endif // CONFIG_KERN_PRI
333 * Terminate the current process
337 TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
339 #if CONFIG_KERN_MONITOR
340 monitor_remove(CurrentProcess);
345 * The following code is BROKEN.
346 * We are freeing our own stack before entering proc_schedule()
347 * BAJO: A correct fix would be to rearrange the scheduler with
348 * an additional parameter which frees the old stack/process
349 * after a context switch.
351 if (CurrentProcess->flags & PF_FREESTACK)
352 heap_free(CurrentProcess->stack_base, CurrentProcess->stack_size);
353 heap_free(CurrentProcess);
356 #if (ARCH & ARCH_EMUL)
357 /* Reinsert process stack in free list */
358 PROC_ATOMIC(ADDHEAD(&StackFreeList, (Node *)CurrentProcess->stack_base));
361 * NOTE: At this point the first two words of what used
362 * to be our stack contain a list node. From now on, we
363 * rely on the compiler not reading/writing the stack.
365 #endif /* ARCH_EMUL */
367 CurrentProcess = NULL;
374 * Get the pointer to the user data of the current process
376 iptr_t proc_currentUserData(void)
378 return CurrentProcess->user_data;