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 * \defgroup kern_proc Process (Threads) management
37 * \brief BeRTOS Kernel core (Process scheduler).
39 * This is the core kernel module. It allows you to create new processes
40 * (which are called \b threads in other systems) and set the priority of
43 * A process needs a work area (called \b stack) to run. To create a process,
44 * you need to declare a stack area, then create the process.
45 * You may also pass NULL for the stack area, if you have enabled kernel heap:
46 * in this case the stack will be automatically allocated.
50 * PROC_DEFINE_STACK(stack1, 200);
52 * void NORETURN proc1_run(void)
56 * LOG_INFO("I'm alive!\n");
64 * Process *p1 = proc_new(proc1_run, NULL, stack1, sizeof(stack1));
65 * // here the process is already running
71 * The Process struct must be regarded as an opaque data type, do not access
72 * any of its members directly.
74 * The entry point function should be declared as NORETURN, because it will
75 * remove a warning and enable compiler optimizations.
77 * You can temporarily disable preemption calling proc_forbid(); remember
78 * to enable it again calling proc_permit().
80 * \note You should hardly need to manually release the CPU; however you
81 * can do it using the cpu_relax() function. It is illegal to release
82 * the CPU with preemption disabled.
84 * \author Bernie Innocenti <bernie@codewiz.org>
86 * $WIZ$ module_name = "kernel"
87 * $WIZ$ module_configuration = "bertos/cfg/cfg_proc.h"
88 * $WIZ$ module_depends = "switch_ctx"
89 * $WIZ$ module_supports = "not atmega103"
95 #include "cfg/cfg_proc.h"
96 #include "cfg/cfg_signal.h"
97 #include "cfg/cfg_monitor.h"
100 #include <struct/list.h> // Node, PriNode
102 #include <cfg/compiler.h>
103 #include <cfg/debug.h> // ASSERT()
105 #include <cpu/types.h> // cpu_stack_t
106 #include <cpu/frame.h> // CPU_SAVED_REGS_CNT
108 /* The following silents warnings on nightly tests. We need to regenerate
109 * all the projects before this can be removed.
111 #ifndef CONFIG_KERN_PRI_INHERIT
112 #define CONFIG_KERN_PRI_INHERIT 0
116 * WARNING: struct Process is considered private, so its definition can change any time
117 * without notice. DO NOT RELY on any field defined here, use only the interface
120 * You have been warned.
122 typedef struct Process
125 PriNode link; /**< Link Process into scheduler lists */
126 # if CONFIG_KERN_PRI_INHERIT
127 PriNode inh_link; /**< Link Process into priority inheritance lists */
128 List inh_list; /**< Priority inheritance list for this Process */
129 Semaphore *inh_blocked_by; /**< Semaphore blocking this Process */
130 int orig_pri; /**< Process priority without considering inheritance */
133 Node link; /**< Link Process into scheduler lists */
135 cpu_stack_t *stack; /**< Per-process SP */
136 iptr_t user_data; /**< Custom data passed to the process */
138 #if CONFIG_KERN_SIGNALS
143 uint16_t flags; /**< Flags */
146 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR
147 cpu_stack_t *stack_base; /**< Base of process stack */
148 size_t stack_size; /**< Size of process stack */
151 /* The actual process entry point */
152 void (*user_entry)(void);
154 #if CONFIG_KERN_MONITOR
165 * Initialize the process subsystem (kernel).
166 * It must be called before using any process related function.
168 void proc_init(void);
170 struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
172 #if !CONFIG_KERN_MONITOR
174 * Create a new named process and schedules it for execution.
176 * When defining the stacksize take into account that you may want at least:
177 * \li save all the registers for each nested function call;
178 * \li have memory for the struct Process, which is positioned at the bottom
180 * \li have some memory for temporary variables inside called functions.
182 * The value given by KERN_MINSTACKSIZE is rather safe to use in the first place.
184 * \param entry Function that the process will execute.
185 * \param data Pointer to user data.
186 * \param size Length of the stack.
187 * \param stack Pointer to the memory area to be used as a stack.
189 * \return Process structure of new created process
190 * if successful, NULL otherwise.
192 #define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
194 #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
198 * Terminate the execution of the current process.
200 void proc_exit(void);
203 * Public scheduling class methods.
205 void proc_yield(void);
207 #if CONFIG_KERN_PREEMPT
208 bool proc_needPreempt(void);
209 void proc_preempt(void);
211 INLINE bool proc_needPreempt(void)
216 INLINE void proc_preempt(void)
221 void proc_rename(struct Process *proc, const char *name);
222 const char *proc_name(struct Process *proc);
223 const char *proc_currentName(void);
226 * Return a pointer to the user data of the current process.
228 * To obtain user data, just call this function inside the process. Remember to cast
229 * the returned pointer to the correct type.
230 * \return Pointer to the user data of the current process.
232 INLINE iptr_t proc_currentUserData(void)
234 extern struct Process *current_process;
235 return current_process->user_data;
238 int proc_testSetup(void);
239 int proc_testRun(void);
240 int proc_testTearDown(void);
243 * Return the context structure of the currently running process.
245 * The details of the Process structure are private to the scheduler.
246 * The address returned by this function is an opaque pointer that can
247 * be passed as an argument to other process-related functions.
249 INLINE struct Process *proc_current(void)
251 extern struct Process *current_process;
252 return current_process;
256 void proc_setPri(struct Process *proc, int pri);
258 INLINE int proc_pri(struct Process *proc)
260 return proc->link.pri;
263 INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
267 INLINE int proc_pri(UNUSED_ARG(struct Process *, proc))
273 #if CONFIG_KERN_PREEMPT
276 * Disable preemptive task switching.
278 * The scheduler maintains a global nesting counter. Task switching is
279 * effectively re-enabled only when the number of calls to proc_permit()
280 * matches the number of calls to proc_forbid().
282 * \note Calling functions that could sleep while task switching is disabled
283 * is dangerous and unsupported.
285 * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
286 * very efficient locking primitive in simple but performance-critical
287 * situations. In all other cases, semaphores offer a more flexible and
288 * fine-grained locking primitive.
292 INLINE void proc_forbid(void)
294 extern cpu_atomic_t preempt_count;
296 * We don't need to protect the counter against other processes.
297 * The reason why is a bit subtle.
299 * If a process gets here, preempt_forbid_cnt can be either 0,
300 * or != 0. In the latter case, preemption is already disabled
301 * and no concurrency issues can occur.
303 * In the former case, we could be preempted just after reading the
304 * value 0 from memory, and a concurrent process might, in fact,
305 * bump the value of preempt_forbid_cnt under our nose!
307 * BUT: if this ever happens, then we won't get another chance to
308 * run until the other process calls proc_permit() to re-enable
309 * preemption. At this point, the value of preempt_forbid_cnt
310 * must be back to 0, and thus what we had originally read from
311 * memory happens to be valid.
313 * No matter how hard you think about it, and how complicated you
314 * make your scenario, the above holds true as long as
315 * "preempt_forbid_cnt != 0" means that no task switching is
321 * Make sure preempt_count is flushed to memory so the preemption
322 * softirq will see the correct value from now on.
328 * Re-enable preemptive task switching.
332 INLINE void proc_permit(void)
334 extern cpu_atomic_t preempt_count;
337 * This is to ensure any global state changed by the process gets
338 * flushed to memory before task switching is re-enabled.
341 /* No need to protect against interrupts here. */
342 ASSERT(preempt_count > 0);
345 * This ensures preempt_count is flushed to memory immediately so the
346 * preemption interrupt sees the correct value.
352 * \return true if preemptive task switching is allowed.
353 * \note This accessor is needed because preempt_count
354 * must be absoultely private.
356 INLINE bool proc_preemptAllowed(void)
358 extern cpu_atomic_t preempt_count;
359 return (preempt_count == 0);
361 #else /* CONFIG_KERN_PREEMPT */
362 #define proc_forbid() /* NOP */
363 #define proc_permit() /* NOP */
364 #define proc_preemptAllowed() (true)
365 #endif /* CONFIG_KERN_PREEMPT */
367 /** Deprecated, use the proc_preemptAllowed() macro. */
368 #define proc_allowed() proc_preemptAllowed()
371 * Execute a block of \a CODE atomically with respect to task scheduling.
373 #define PROC_ATOMIC(CODE) \
381 * Default stack size for each thread, in bytes.
383 * The goal here is to allow a minimal task to save all of its
384 * registers twice, plus push a maximum of 32 variables on the
385 * stack. We add also struct Process size since we save it into the process'
388 * The actual size computed by the default formula greatly depends on what
389 * options are active and on the architecture.
391 * Note that on most 16bit architectures, interrupts will also
392 * run on the stack of the currently running process. Nested
393 * interrupts will greatly increases the amount of stack space
394 * required per process. Use irqmanager to minimize stack
398 #if (ARCH & ARCH_EMUL)
399 /* We need a large stack because system libraries are bloated */
400 #define KERN_MINSTACKSIZE 65536
402 #if CONFIG_KERN_PREEMPT
404 * A preemptible kernel needs a larger stack compared to the
405 * cooperative case. A task can be interrupted anytime in each
406 * node of the call graph, at any level of depth. This may
407 * result in a higher stack consumption, to call the ISR, save
408 * the current user context and to execute the kernel
409 * preemption routines implemented as ISR prologue and
410 * epilogue. All these calls are nested into the process stack.
412 * So, to reduce the risk of stack overflow/underflow problems
413 * add a x2 to the portion stack reserved to the user process.
415 #define KERN_MINSTACKSIZE \
416 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
417 + 32 * sizeof(int) * 2)
419 #define KERN_MINSTACKSIZE \
420 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
422 #endif /* CONFIG_KERN_PREEMPT */
426 #ifndef CONFIG_KERN_MINSTACKSIZE
427 /* For backward compatibility */
428 #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
430 #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
434 * Utility macro to allocate a stack of size \a size.
436 * This macro define a static stack for one process and do
437 * check if given stack size is enough to run process.
438 * \note If you plan to use kprintf() and similar functions, you will need
439 * at least KERN_MINSTACKSIZE * 2 bytes.
441 * \param name Variable name for the stack.
442 * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
444 #define PROC_DEFINE_STACK(name, size) \
445 cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \
446 STATIC_ASSERT((size) >= KERN_MINSTACKSIZE);
448 /* Memory fill codes to help debugging */
449 #if CONFIG_KERN_MONITOR
450 #include <cpu/types.h>
451 #if (SIZEOF_CPUSTACK_T == 1)
452 /* 8bit cpu_stack_t */
453 #define CONFIG_KERN_STACKFILLCODE 0xA5
454 #define CONFIG_KERN_MEMFILLCODE 0xDB
455 #elif (SIZEOF_CPUSTACK_T == 2)
456 /* 16bit cpu_stack_t */
457 #define CONFIG_KERN_STACKFILLCODE 0xA5A5
458 #define CONFIG_KERN_MEMFILLCODE 0xDBDB
459 #elif (SIZEOF_CPUSTACK_T == 4)
460 /* 32bit cpu_stack_t */
461 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
462 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
463 #elif (SIZEOF_CPUSTACK_T == 8)
464 /* 64bit cpu_stack_t */
465 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
466 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
468 #error No cpu_stack_t size supported!
471 /** \} */ //defgroup kern_proc
473 #endif /* KERN_PROC_H */