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_proc.h"
45 #include "cfg/cfg_monitor.h"
46 #include <cfg/macros.h> // ROUND_UP2
47 #include <cfg/module.h>
48 #include <cfg/depend.h> // CONFIG_DEPEND()
51 #include <cpu/types.h>
53 #include <cpu/frame.h>
56 #include <struct/heap.h>
59 #include <string.h> /* memset() */
62 * The scheduer tracks ready processes by enqueuing them in the
65 * \note Access to the list must occur while interrupts are disabled.
67 REGISTER List ProcReadyList;
70 * Holds a pointer to the TCB of the currently running process.
72 * \note User applications should use proc_current() to retrieve this value.
74 REGISTER Process *CurrentProcess;
76 #if (ARCH & ARCH_EMUL)
78 * In some hosted environments, we must emulate the stack on the real
79 * process stack to satisfy consistency checks in system libraries and
80 * because some ABIs place trampolines on the stack.
82 * Access to this list must be protected by PROC_ATOMIC().
87 cpu_stack_t proc_stacks[NPROC][(64 * 1024) / sizeof(cpu_stack_t)];
90 /** The main process (the one that executes main()). */
91 struct Process MainProcess;
94 static void proc_init_struct(Process *proc)
96 /* Avoid warning for unused argument. */
99 #if CONFIG_KERN_SIGNALS
118 LIST_INIT(&ProcReadyList);
121 LIST_INIT(&StackFreeList);
122 for (int i = 0; i < NPROC; i++)
123 ADDTAIL(&StackFreeList, (Node *)proc_stacks[i]);
127 * We "promote" the current context into a real process. The only thing we have
128 * to do is create a PCB and make it current. We don't need to setup the stack
129 * pointer because it will be written the first time we switch to another process.
131 proc_init_struct(&MainProcess);
132 CurrentProcess = &MainProcess;
134 #if CONFIG_KERN_MONITOR
136 monitor_add(CurrentProcess, "main");
139 #if CONFIG_KERN_PREEMPT
147 * Create a new process, starting at the provided entry point.
149 * \return Process structure of new created process
150 * if successful, NULL otherwise.
152 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)
155 const size_t PROC_SIZE_WORDS = ROUND_UP2(sizeof(Process), sizeof(cpu_stack_t)) / sizeof(cpu_stack_t);
157 bool free_stack = false;
159 TRACEMSG("name=%s", name);
161 #if (ARCH & ARCH_EMUL)
162 /* Ignore stack provided by caller and use the large enough default instead. */
163 PROC_ATOMIC(stack_base = (cpu_stack_t *)list_remHead(&StackFreeList));
166 stack_size = CONFIG_KERN_MINSTACKSIZE;
167 #elif CONFIG_KERN_HEAP
168 /* Did the caller provide a stack for us? */
171 /* Did the caller specify the desired stack size? */
173 stack_size = CONFIG_KERN_MINSTACKSIZE;
175 /* Allocate stack dinamically */
176 if (!(stack_base = heap_alloc(stack_size)))
182 #else // !ARCH_EMUL && !CONFIG_KERN_HEAP
184 /* Stack must have been provided by the user */
185 ASSERT_VALID_PTR(stack_base);
188 #endif // !ARCH_EMUL && !CONFIG_KERN_HEAP
190 #if CONFIG_KERN_MONITOR
192 * Fill-in the stack with a special marker to help debugging.
193 * On 64bit platforms, CONFIG_KERN_STACKFILLCODE is larger
194 * than an int, so the (int) cast is required to silence the
195 * warning for truncating its size.
197 memset(stack_base, (int)CONFIG_KERN_STACKFILLCODE, stack_size);
200 /* Initialize the process control block */
201 if (CPU_STACK_GROWS_UPWARD)
203 proc = (Process *)stack_base;
204 proc->stack = stack_base + PROC_SIZE_WORDS;
205 // On some architecture stack should be aligned, so we do it.
206 proc->stack = (cpu_stack_t *)((uintptr_t)proc->stack + (sizeof(cpu_aligned_stack_t) - ((uintptr_t)proc->stack % sizeof(cpu_aligned_stack_t))));
207 if (CPU_SP_ON_EMPTY_SLOT)
212 proc = (Process *)(stack_base + stack_size / sizeof(cpu_stack_t) - PROC_SIZE_WORDS);
213 // On some architecture stack should be aligned, so we do it.
214 proc->stack = (cpu_stack_t *)((uintptr_t)proc - ((uintptr_t)proc % sizeof(cpu_aligned_stack_t)));
215 if (CPU_SP_ON_EMPTY_SLOT)
218 /* Ensure stack is aligned */
219 ASSERT((uintptr_t)proc->stack % sizeof(cpu_aligned_stack_t) == 0);
221 stack_size -= PROC_SIZE_WORDS * sizeof(cpu_stack_t);
222 proc_init_struct(proc);
223 proc->user_data = data;
225 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR | (ARCH & ARCH_EMUL)
226 proc->stack_base = stack_base;
227 proc->stack_size = stack_size;
230 proc->flags |= PF_FREESTACK;
234 #if CONFIG_KERN_PREEMPT
236 getcontext(&proc->context);
237 proc->context.uc_stack.ss_sp = proc->stack;
238 proc->context.uc_stack.ss_size = stack_size - 1;
239 proc->context.uc_link = NULL;
240 makecontext(&proc->context, (void (*)(void))proc_entry, 1, entry);
242 #else // !CONFIG_KERN_PREEMPT
244 CPU_CREATE_NEW_STACK(proc->stack, entry, proc_exit);
246 #endif // CONFIG_KERN_PREEMPT
248 #if CONFIG_KERN_MONITOR
249 monitor_add(proc, name);
252 /* Add to ready list */
253 ATOMIC(SCHED_ENQUEUE(proc));
259 * Return the name of the specified process.
261 * NULL is a legal argument and will return the name "<NULL>".
263 const char *proc_name(struct Process *proc)
265 #if CONFIG_KERN_MONITOR
266 return proc ? proc->monitor.name : "<NULL>";
273 /// Return the name of the currently running process
274 const char *proc_currentName(void)
276 return proc_name(proc_current());
280 void proc_rename(struct Process *proc, const char *name)
282 #if CONFIG_KERN_MONITOR
283 monitor_rename(proc, name);
285 (void)proc; (void)name;
292 * Change the scheduling priority of a process.
294 * Process piorities are signed ints, whereas a larger integer value means
295 * higher scheduling priority. The default priority for new processes is 0.
296 * The idle process runs with the lowest possible priority: INT_MIN.
298 * A process with a higher priority always preempts lower priority processes.
299 * Processes of equal priority share the CPU time according to a simple
300 * round-robin policy.
302 * As a general rule to maximize responsiveness, compute-bound processes
303 * should be assigned negative priorities and tight, interactive processes
304 * should be assigned positive priorities.
306 * To avoid interfering with system background activities such as input
307 * processing, application processes should remain within the range -10
310 void proc_setPri(struct Process *proc, int pri)
312 if (proc->link.pri == pri)
315 proc->link.pri = pri;
317 if (proc != CurrentProcess)
320 ATOMIC(sched_reenqueue(proc));
324 #endif // CONFIG_KERN_PRI
327 * Terminate the current process
331 TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
333 #if CONFIG_KERN_MONITOR
334 monitor_remove(CurrentProcess);
339 * The following code is BROKEN.
340 * We are freeing our own stack before entering proc_schedule()
341 * BAJO: A correct fix would be to rearrange the scheduler with
342 * an additional parameter which frees the old stack/process
343 * after a context switch.
345 if (CurrentProcess->flags & PF_FREESTACK)
346 heap_free(CurrentProcess->stack_base, CurrentProcess->stack_size);
347 heap_free(CurrentProcess);
350 #if (ARCH & ARCH_EMUL)
351 /* Reinsert process stack in free list */
352 PROC_ATOMIC(ADDHEAD(&StackFreeList, (Node *)CurrentProcess->stack_base));
355 * NOTE: At this point the first two words of what used
356 * to be our stack contain a list node. From now on, we
357 * rely on the compiler not reading/writing the stack.
359 #endif /* ARCH_EMUL */
361 CurrentProcess = NULL;
368 * Get the pointer to the user data of the current process
370 iptr_t proc_currentUserData(void)
372 return CurrentProcess->user_data;