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"
99 #include <struct/list.h> // Node, PriNode
101 #include <cfg/compiler.h>
102 #include <cfg/debug.h> // ASSERT()
104 #include <cpu/types.h> // cpu_stack_t
105 #include <cpu/frame.h> // CPU_SAVED_REGS_CNT
108 * WARNING: struct Process is considered private, so its definition can change any time
109 * without notice. DO NOT RELY on any field defined here, use only the interface
112 * You have been warned.
114 typedef struct Process
117 PriNode link; /**< Link Process into scheduler lists */
119 Node link; /**< Link Process into scheduler lists */
121 cpu_stack_t *stack; /**< Per-process SP */
122 iptr_t user_data; /**< Custom data passed to the process */
124 #if CONFIG_KERN_SIGNALS
129 uint16_t flags; /**< Flags */
132 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR
133 cpu_stack_t *stack_base; /**< Base of process stack */
134 size_t stack_size; /**< Size of process stack */
137 /* The actual process entry point */
138 void (*user_entry)(void);
140 #if CONFIG_KERN_MONITOR
151 * Initialize the process subsystem (kernel).
152 * It must be called before using any process related function.
154 void proc_init(void);
156 struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
158 #if !CONFIG_KERN_MONITOR
160 * Create a new named process and schedules it for execution.
162 * When defining the stacksize take into account that you may want at least:
163 * \li save all the registers for each nested function call;
164 * \li have memory for the struct Process, which is positioned at the bottom
166 * \li have some memory for temporary variables inside called functions.
168 * The value given by KERN_MINSTACKSIZE is rather safe to use in the first place.
170 * \param entry Function that the process will execute.
171 * \param data Pointer to user data.
172 * \param size Length of the stack.
173 * \param stack Pointer to the memory area to be used as a stack.
175 * \return Process structure of new created process
176 * if successful, NULL otherwise.
178 #define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
180 #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
184 * Terminate the execution of the current process.
186 void proc_exit(void);
189 * Public scheduling class methods.
191 void proc_yield(void);
193 #if CONFIG_KERN_PREEMPT
194 bool proc_needPreempt(void);
195 void proc_preempt(void);
197 INLINE bool proc_needPreempt(void)
202 INLINE void proc_preempt(void)
207 void proc_rename(struct Process *proc, const char *name);
208 const char *proc_name(struct Process *proc);
209 const char *proc_currentName(void);
212 * Return a pointer to the user data of the current process.
214 * To obtain user data, just call this function inside the process. Remember to cast
215 * the returned pointer to the correct type.
216 * \return Pointer to the user data of the current process.
218 INLINE iptr_t proc_currentUserData(void)
220 extern struct Process *current_process;
221 return current_process->user_data;
224 int proc_testSetup(void);
225 int proc_testRun(void);
226 int proc_testTearDown(void);
229 * Return the context structure of the currently running process.
231 * The details of the Process structure are private to the scheduler.
232 * The address returned by this function is an opaque pointer that can
233 * be passed as an argument to other process-related functions.
235 INLINE struct Process *proc_current(void)
237 extern struct Process *current_process;
238 return current_process;
242 void proc_setPri(struct Process *proc, int pri);
244 INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
249 #if CONFIG_KERN_PREEMPT
252 * Disable preemptive task switching.
254 * The scheduler maintains a global nesting counter. Task switching is
255 * effectively re-enabled only when the number of calls to proc_permit()
256 * matches the number of calls to proc_forbid().
258 * \note Calling functions that could sleep while task switching is disabled
259 * is dangerous and unsupported.
261 * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
262 * very efficient locking primitive in simple but performance-critical
263 * situations. In all other cases, semaphores offer a more flexible and
264 * fine-grained locking primitive.
268 INLINE void proc_forbid(void)
270 extern cpu_atomic_t preempt_count;
272 * We don't need to protect the counter against other processes.
273 * The reason why is a bit subtle.
275 * If a process gets here, preempt_forbid_cnt can be either 0,
276 * or != 0. In the latter case, preemption is already disabled
277 * and no concurrency issues can occur.
279 * In the former case, we could be preempted just after reading the
280 * value 0 from memory, and a concurrent process might, in fact,
281 * bump the value of preempt_forbid_cnt under our nose!
283 * BUT: if this ever happens, then we won't get another chance to
284 * run until the other process calls proc_permit() to re-enable
285 * preemption. At this point, the value of preempt_forbid_cnt
286 * must be back to 0, and thus what we had originally read from
287 * memory happens to be valid.
289 * No matter how hard you think about it, and how complicated you
290 * make your scenario, the above holds true as long as
291 * "preempt_forbid_cnt != 0" means that no task switching is
297 * Make sure preempt_count is flushed to memory so the preemption
298 * softirq will see the correct value from now on.
304 * Re-enable preemptive task switching.
308 INLINE void proc_permit(void)
310 extern cpu_atomic_t preempt_count;
313 * This is to ensure any global state changed by the process gets
314 * flushed to memory before task switching is re-enabled.
317 /* No need to protect against interrupts here. */
318 ASSERT(preempt_count > 0);
321 * This ensures preempt_count is flushed to memory immediately so the
322 * preemption interrupt sees the correct value.
328 * \return true if preemptive task switching is allowed.
329 * \note This accessor is needed because preempt_count
330 * must be absoultely private.
332 INLINE bool proc_preemptAllowed(void)
334 extern cpu_atomic_t preempt_count;
335 return (preempt_count == 0);
337 #else /* CONFIG_KERN_PREEMPT */
338 #define proc_forbid() /* NOP */
339 #define proc_permit() /* NOP */
340 #define proc_preemptAllowed() (true)
341 #endif /* CONFIG_KERN_PREEMPT */
343 /** Deprecated, use the proc_preemptAllowed() macro. */
344 #define proc_allowed() proc_preemptAllowed()
347 * Execute a block of \a CODE atomically with respect to task scheduling.
349 #define PROC_ATOMIC(CODE) \
357 * Default stack size for each thread, in bytes.
359 * The goal here is to allow a minimal task to save all of its
360 * registers twice, plus push a maximum of 32 variables on the
361 * stack. We add also struct Process size since we save it into the process'
364 * The actual size computed by the default formula greatly depends on what
365 * options are active and on the architecture.
367 * Note that on most 16bit architectures, interrupts will also
368 * run on the stack of the currently running process. Nested
369 * interrupts will greatly increases the amount of stack space
370 * required per process. Use irqmanager to minimize stack
374 #if (ARCH & ARCH_EMUL)
375 /* We need a large stack because system libraries are bloated */
376 #define KERN_MINSTACKSIZE 65536
378 #if CONFIG_KERN_PREEMPT
380 * A preemptible kernel needs a larger stack compared to the
381 * cooperative case. A task can be interrupted anytime in each
382 * node of the call graph, at any level of depth. This may
383 * result in a higher stack consumption, to call the ISR, save
384 * the current user context and to execute the kernel
385 * preemption routines implemented as ISR prologue and
386 * epilogue. All these calls are nested into the process stack.
388 * So, to reduce the risk of stack overflow/underflow problems
389 * add a x2 to the portion stack reserved to the user process.
391 #define KERN_MINSTACKSIZE \
392 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
393 + 32 * sizeof(int) * 2)
395 #define KERN_MINSTACKSIZE \
396 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
398 #endif /* CONFIG_KERN_PREEMPT */
402 #ifndef CONFIG_KERN_MINSTACKSIZE
403 /* For backward compatibility */
404 #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
406 #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
410 * Utility macro to allocate a stack of size \a size.
412 * This macro define a static stack for one process and do
413 * check if given stack size is enough to run process.
414 * \note If you plan to use kprintf() and similar functions, you will need
415 * at least KERN_MINSTACKSIZE * 2 bytes.
417 * \param name Variable name for the stack.
418 * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
420 #define PROC_DEFINE_STACK(name, size) \
421 cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \
422 STATIC_ASSERT((size) >= KERN_MINSTACKSIZE);
424 /* Memory fill codes to help debugging */
425 #if CONFIG_KERN_MONITOR
426 #include <cpu/types.h>
427 #if (SIZEOF_CPUSTACK_T == 1)
428 /* 8bit cpu_stack_t */
429 #define CONFIG_KERN_STACKFILLCODE 0xA5
430 #define CONFIG_KERN_MEMFILLCODE 0xDB
431 #elif (SIZEOF_CPUSTACK_T == 2)
432 /* 16bit cpu_stack_t */
433 #define CONFIG_KERN_STACKFILLCODE 0xA5A5
434 #define CONFIG_KERN_MEMFILLCODE 0xDBDB
435 #elif (SIZEOF_CPUSTACK_T == 4)
436 /* 32bit cpu_stack_t */
437 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
438 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
439 #elif (SIZEOF_CPUSTACK_T == 8)
440 /* 64bit cpu_stack_t */
441 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
442 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
444 #error No cpu_stack_t size supported!
447 /** \} */ //defgroup kern_proc
449 #endif /* KERN_PROC_H */