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.
35 * \author Bernie Innocenti <bernie@codewiz.org>
36 * \author Stefano Fedrigo <aleph@develer.com>
42 #include "cfg/cfg_proc.h"
43 #define LOG_LEVEL KERN_LOG_LEVEL
44 #define LOG_FORMAT KERN_LOG_FORMAT
47 #include "cfg/cfg_arch.h" // ARCH_EMUL
48 #include "cfg/cfg_monitor.h"
49 #include <cfg/macros.h> // ROUND_UP2
50 #include <cfg/module.h>
51 #include <cfg/depend.h> // CONFIG_DEPEND()
54 #include <cpu/types.h>
56 #include <cpu/frame.h>
59 #include <struct/heap.h>
62 #include <string.h> /* memset() */
65 * The scheduer tracks ready processes by enqueuing them in the
68 * \note Access to the list must occur while interrupts are disabled.
70 REGISTER List ProcReadyList;
73 * Holds a pointer to the TCB of the currently running process.
75 * \note User applications should use proc_current() to retrieve this value.
77 REGISTER Process *CurrentProcess;
79 #if (ARCH & ARCH_EMUL)
81 * In some hosted environments, we must emulate the stack on the real
82 * process stack to satisfy consistency checks in system libraries and
83 * because some ABIs place trampolines on the stack.
85 * Access to this list must be protected by PROC_ATOMIC().
90 cpu_stack_t proc_stacks[NPROC][(64 * 1024) / sizeof(cpu_stack_t)];
93 /** The main process (the one that executes main()). */
94 struct Process MainProcess;
97 static void proc_init_struct(Process *proc)
99 /* Avoid warning for unused argument. */
102 #if CONFIG_KERN_SIGNALS
121 LIST_INIT(&ProcReadyList);
124 LIST_INIT(&StackFreeList);
125 for (int i = 0; i < NPROC; i++)
126 ADDTAIL(&StackFreeList, (Node *)proc_stacks[i]);
130 * We "promote" the current context into a real process. The only thing we have
131 * to do is create a PCB and make it current. We don't need to setup the stack
132 * pointer because it will be written the first time we switch to another process.
134 proc_init_struct(&MainProcess);
135 CurrentProcess = &MainProcess;
137 #if CONFIG_KERN_MONITOR
139 monitor_add(CurrentProcess, "main");
142 #if CONFIG_KERN_PREEMPT
150 * Create a new process, starting at the provided entry point.
155 * proc_new(entry, data, stacksize, stack)
157 * is a more convenient way to create a process, as you don't have to specify
160 * \return Process structure of new created process
161 * if successful, NULL otherwise.
163 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)
166 const size_t PROC_SIZE_WORDS = ROUND_UP2(sizeof(Process), sizeof(cpu_stack_t)) / sizeof(cpu_stack_t);
168 bool free_stack = false;
170 LOG_INFO("name=%s", name);
172 #if (ARCH & ARCH_EMUL)
173 /* Ignore stack provided by caller and use the large enough default instead. */
174 PROC_ATOMIC(stack_base = (cpu_stack_t *)list_remHead(&StackFreeList));
177 stack_size = KERN_MINSTACKSIZE;
178 #elif CONFIG_KERN_HEAP
179 /* Did the caller provide a stack for us? */
182 /* Did the caller specify the desired stack size? */
184 stack_size = KERN_MINSTACKSIZE;
186 /* Allocate stack dinamically */
187 if (!(stack_base = heap_alloc(stack_size)))
193 #else // !ARCH_EMUL && !CONFIG_KERN_HEAP
195 /* Stack must have been provided by the user */
196 ASSERT_VALID_PTR(stack_base);
199 #endif // !ARCH_EMUL && !CONFIG_KERN_HEAP
201 #if CONFIG_KERN_MONITOR
203 * Fill-in the stack with a special marker to help debugging.
204 * On 64bit platforms, CONFIG_KERN_STACKFILLCODE is larger
205 * than an int, so the (int) cast is required to silence the
206 * warning for truncating its size.
208 memset(stack_base, (int)CONFIG_KERN_STACKFILLCODE, stack_size);
211 /* Initialize the process control block */
212 if (CPU_STACK_GROWS_UPWARD)
214 proc = (Process *)stack_base;
215 proc->stack = stack_base + PROC_SIZE_WORDS;
216 // On some architecture stack should be aligned, so we do it.
217 proc->stack = (cpu_stack_t *)((uintptr_t)proc->stack + (sizeof(cpu_aligned_stack_t) - ((uintptr_t)proc->stack % sizeof(cpu_aligned_stack_t))));
218 if (CPU_SP_ON_EMPTY_SLOT)
223 proc = (Process *)(stack_base + stack_size / sizeof(cpu_stack_t) - PROC_SIZE_WORDS);
224 // On some architecture stack should be aligned, so we do it.
225 proc->stack = (cpu_stack_t *)((uintptr_t)proc - ((uintptr_t)proc % sizeof(cpu_aligned_stack_t)));
226 if (CPU_SP_ON_EMPTY_SLOT)
229 /* Ensure stack is aligned */
230 ASSERT((uintptr_t)proc->stack % sizeof(cpu_aligned_stack_t) == 0);
232 stack_size -= PROC_SIZE_WORDS * sizeof(cpu_stack_t);
233 proc_init_struct(proc);
234 proc->user_data = data;
236 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR | (ARCH & ARCH_EMUL)
237 proc->stack_base = stack_base;
238 proc->stack_size = stack_size;
241 proc->flags |= PF_FREESTACK;
245 #if CONFIG_KERN_PREEMPT
247 getcontext(&proc->context);
248 proc->context.uc_stack.ss_sp = proc->stack;
249 proc->context.uc_stack.ss_size = stack_size - 1;
250 proc->context.uc_link = NULL;
251 makecontext(&proc->context, (void (*)(void))proc_entry, 1, entry);
253 #else // !CONFIG_KERN_PREEMPT
255 CPU_CREATE_NEW_STACK(proc->stack, entry, proc_exit);
257 #endif // CONFIG_KERN_PREEMPT
259 #if CONFIG_KERN_MONITOR
260 monitor_add(proc, name);
263 /* Add to ready list */
264 ATOMIC(SCHED_ENQUEUE(proc));
270 * Return the name of the specified process.
272 * NULL is a legal argument and will return the name "<NULL>".
274 const char *proc_name(struct Process *proc)
276 #if CONFIG_KERN_MONITOR
277 return proc ? proc->monitor.name : "<NULL>";
284 /// Return the name of the currently running process
285 const char *proc_currentName(void)
287 return proc_name(proc_current());
291 void proc_rename(struct Process *proc, const char *name)
293 #if CONFIG_KERN_MONITOR
294 monitor_rename(proc, name);
296 (void)proc; (void)name;
303 * Change the scheduling priority of a process.
305 * Process piorities are signed ints, whereas a larger integer value means
306 * higher scheduling priority. The default priority for new processes is 0.
307 * The idle process runs with the lowest possible priority: INT_MIN.
309 * A process with a higher priority always preempts lower priority processes.
310 * Processes of equal priority share the CPU time according to a simple
311 * round-robin policy.
313 * As a general rule to maximize responsiveness, compute-bound processes
314 * should be assigned negative priorities and tight, interactive processes
315 * should be assigned positive priorities.
317 * To avoid interfering with system background activities such as input
318 * processing, application processes should remain within the range -10
321 void proc_setPri(struct Process *proc, int pri)
323 if (proc->link.pri == pri)
326 proc->link.pri = pri;
328 if (proc != CurrentProcess)
331 ATOMIC(sched_reenqueue(proc));
335 #endif // CONFIG_KERN_PRI
338 * Terminate the current process
342 LOG_INFO("%p:%s", CurrentProcess, proc_currentName());
344 #if CONFIG_KERN_MONITOR
345 monitor_remove(CurrentProcess);
350 * The following code is BROKEN.
351 * We are freeing our own stack before entering proc_schedule()
352 * BAJO: A correct fix would be to rearrange the scheduler with
353 * an additional parameter which frees the old stack/process
354 * after a context switch.
356 if (CurrentProcess->flags & PF_FREESTACK)
357 heap_free(CurrentProcess->stack_base, CurrentProcess->stack_size);
358 heap_free(CurrentProcess);
361 #if (ARCH & ARCH_EMUL)
362 /* Reinsert process stack in free list */
363 PROC_ATOMIC(ADDHEAD(&StackFreeList, (Node *)CurrentProcess->stack_base));
366 * NOTE: At this point the first two words of what used
367 * to be our stack contain a list node. From now on, we
368 * rely on the compiler not reading/writing the stack.
370 #endif /* ARCH_EMUL */
372 CurrentProcess = NULL;
379 * Get the pointer to the user data of the current process
381 iptr_t proc_currentUserData(void)
383 return CurrentProcess->user_data;