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 Kernel facilities
36 * \defgroup kern_proc Process (Threads) management
39 * \brief BeRTOS Kernel core (Process scheduler).
41 * \author Bernie Innocenti <bernie@codewiz.org>
43 * $WIZ$ module_name = "kernel"
44 * $WIZ$ module_configuration = "bertos/cfg/cfg_proc.h"
45 * $WIZ$ module_depends = "switch_ctx"
46 * $WIZ$ module_supports = "not atmega103"
52 #include "cfg/cfg_proc.h"
53 #include "cfg/cfg_signal.h"
54 #include "cfg/cfg_monitor.h"
56 #include <struct/list.h> // Node, PriNode
58 #include <cfg/compiler.h>
59 #include <cfg/debug.h> // ASSERT()
61 #include <cpu/types.h> // cpu_stack_t
62 #include <cpu/frame.h> // CPU_SAVED_REGS_CNT
65 * WARNING: struct Process is considered private, so its definition can change any time
66 * without notice. DO NOT RELY on any field defined here, use only the interface
69 * You have been warned.
71 typedef struct Process
74 PriNode link; /**< Link Process into scheduler lists */
76 Node link; /**< Link Process into scheduler lists */
78 cpu_stack_t *stack; /**< Per-process SP */
79 iptr_t user_data; /**< Custom data passed to the process */
81 #if CONFIG_KERN_SIGNALS
82 sigmask_t sig_wait; /**< Signals the process is waiting for */
83 sigmask_t sig_recv; /**< Received signals */
87 uint16_t flags; /**< Flags */
90 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR
91 cpu_stack_t *stack_base; /**< Base of process stack */
92 size_t stack_size; /**< Size of process stack */
95 /* The actual process entry point */
96 void (*user_entry)(void);
98 #if CONFIG_KERN_MONITOR
109 * Initialize the process subsystem (kernel).
110 * It must be called before using any process related function.
112 void proc_init(void);
114 struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
116 #if !CONFIG_KERN_MONITOR
118 * Create a new named process and schedules it for execution.
120 * When defining the stacksize take into account that you may want at least:
121 * \li save all the registers for each nested function call;
122 * \li have memory for the struct Process, which is positioned at the bottom
124 * \li have some memory for temporary variables inside called functions.
126 * The value given by KERN_MINSTACKSIZE is rather safe to use in the first place.
128 * \param entry Function that the process will execute.
129 * \param data Pointer to user data.
130 * \param size Length of the stack.
131 * \param stack Pointer to the memory area to be used as a stack.
133 * \return Process structure of new created process
134 * if successful, NULL otherwise.
136 #define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
138 #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
142 * Terminate the execution of the current process.
144 void proc_exit(void);
147 * Public scheduling class methods.
149 void proc_yield(void);
151 #if CONFIG_KERN_PREEMPT
152 bool proc_needPreempt(void);
153 void proc_preempt(void);
155 INLINE bool proc_needPreempt(void)
160 INLINE void proc_preempt(void)
165 void proc_rename(struct Process *proc, const char *name);
166 const char *proc_name(struct Process *proc);
167 const char *proc_currentName(void);
170 * Return a pointer to the user data of the current process.
172 * To obtain user data, just call this function inside the process. Remember to cast
173 * the returned pointer to the correct type.
174 * \return Pointer to the user data of the current process.
176 INLINE iptr_t proc_currentUserData(void)
178 extern struct Process *current_process;
179 return current_process->user_data;
182 int proc_testSetup(void);
183 int proc_testRun(void);
184 int proc_testTearDown(void);
187 * Return the context structure of the currently running process.
189 * The details of the Process structure are private to the scheduler.
190 * The address returned by this function is an opaque pointer that can
191 * be passed as an argument to other process-related functions.
193 INLINE struct Process *proc_current(void)
195 extern struct Process *current_process;
196 return current_process;
200 void proc_setPri(struct Process *proc, int pri);
202 INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
207 #if CONFIG_KERN_PREEMPT
210 * Disable preemptive task switching.
212 * The scheduler maintains a global nesting counter. Task switching is
213 * effectively re-enabled only when the number of calls to proc_permit()
214 * matches the number of calls to proc_forbid().
216 * \note Calling functions that could sleep while task switching is disabled
217 * is dangerous and unsupported.
219 * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
220 * very efficient locking primitive in simple but performance-critical
221 * situations. In all other cases, semaphores offer a more flexible and
222 * fine-grained locking primitive.
226 INLINE void proc_forbid(void)
228 extern cpu_atomic_t preempt_count;
230 * We don't need to protect the counter against other processes.
231 * The reason why is a bit subtle.
233 * If a process gets here, preempt_forbid_cnt can be either 0,
234 * or != 0. In the latter case, preemption is already disabled
235 * and no concurrency issues can occur.
237 * In the former case, we could be preempted just after reading the
238 * value 0 from memory, and a concurrent process might, in fact,
239 * bump the value of preempt_forbid_cnt under our nose!
241 * BUT: if this ever happens, then we won't get another chance to
242 * run until the other process calls proc_permit() to re-enable
243 * preemption. At this point, the value of preempt_forbid_cnt
244 * must be back to 0, and thus what we had originally read from
245 * memory happens to be valid.
247 * No matter how hard you think about it, and how complicated you
248 * make your scenario, the above holds true as long as
249 * "preempt_forbid_cnt != 0" means that no task switching is
255 * Make sure preempt_count is flushed to memory so the preemption
256 * softirq will see the correct value from now on.
262 * Re-enable preemptive task switching.
266 INLINE void proc_permit(void)
268 extern cpu_atomic_t preempt_count;
271 * This is to ensure any global state changed by the process gets
272 * flushed to memory before task switching is re-enabled.
275 /* No need to protect against interrupts here. */
276 ASSERT(preempt_count > 0);
279 * This ensures preempt_count is flushed to memory immediately so the
280 * preemption interrupt sees the correct value.
286 * \return true if preemptive task switching is allowed.
287 * \note This accessor is needed because preempt_count
288 * must be absoultely private.
290 INLINE bool proc_preemptAllowed(void)
292 extern cpu_atomic_t preempt_count;
293 return (preempt_count == 0);
295 #else /* CONFIG_KERN_PREEMPT */
296 #define proc_forbid() /* NOP */
297 #define proc_permit() /* NOP */
298 #define proc_preemptAllowed() (true)
299 #endif /* CONFIG_KERN_PREEMPT */
301 /** Deprecated, use the proc_preemptAllowed() macro. */
302 #define proc_allowed() proc_preemptAllowed()
305 * Execute a block of \a CODE atomically with respect to task scheduling.
307 #define PROC_ATOMIC(CODE) \
315 * Default stack size for each thread, in bytes.
317 * The goal here is to allow a minimal task to save all of its
318 * registers twice, plus push a maximum of 32 variables on the
319 * stack. We add also struct Process size since we save it into the process'
322 * The actual size computed by the default formula greatly depends on what
323 * options are active and on the architecture.
325 * Note that on most 16bit architectures, interrupts will also
326 * run on the stack of the currently running process. Nested
327 * interrupts will greatly increases the amount of stack space
328 * required per process. Use irqmanager to minimize stack
332 #if (ARCH & ARCH_EMUL)
333 /* We need a large stack because system libraries are bloated */
334 #define KERN_MINSTACKSIZE 65536
336 #if CONFIG_KERN_PREEMPT
338 * A preemptible kernel needs a larger stack compared to the
339 * cooperative case. A task can be interrupted anytime in each
340 * node of the call graph, at any level of depth. This may
341 * result in a higher stack consumption, to call the ISR, save
342 * the current user context and to execute the kernel
343 * preemption routines implemented as ISR prologue and
344 * epilogue. All these calls are nested into the process stack.
346 * So, to reduce the risk of stack overflow/underflow problems
347 * add a x2 to the portion stack reserved to the user process.
349 #define KERN_MINSTACKSIZE \
350 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
351 + 32 * sizeof(int) * 2)
353 #define KERN_MINSTACKSIZE \
354 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
356 #endif /* CONFIG_KERN_PREEMPT */
360 #ifndef CONFIG_KERN_MINSTACKSIZE
361 /* For backward compatibility */
362 #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
364 #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
368 * Utility macro to allocate a stack of size \a size.
370 * This macro define a static stack for one process and do
371 * check if given stack size is enough to run process.
372 * \note If you plan to use kprintf() and similar functions, you will need
373 * at least KERN_MINSTACKSIZE * 2 bytes.
375 * \param name Variable name for the stack.
376 * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
378 #define PROC_DEFINE_STACK(name, size) \
379 cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \
380 STATIC_ASSERT((size) >= KERN_MINSTACKSIZE);
382 /* Memory fill codes to help debugging */
383 #if CONFIG_KERN_MONITOR
384 #include <cpu/types.h>
385 #if (SIZEOF_CPUSTACK_T == 1)
386 /* 8bit cpu_stack_t */
387 #define CONFIG_KERN_STACKFILLCODE 0xA5
388 #define CONFIG_KERN_MEMFILLCODE 0xDB
389 #elif (SIZEOF_CPUSTACK_T == 2)
390 /* 16bit cpu_stack_t */
391 #define CONFIG_KERN_STACKFILLCODE 0xA5A5
392 #define CONFIG_KERN_MEMFILLCODE 0xDBDB
393 #elif (SIZEOF_CPUSTACK_T == 4)
394 /* 32bit cpu_stack_t */
395 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
396 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
397 #elif (SIZEOF_CPUSTACK_T == 8)
398 /* 64bit cpu_stack_t */
399 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
400 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
402 #error No cpu_stack_t size supported!
405 /** \} */ //defgroup kern_proc
406 /** \} */ //defgroup kern
408 #endif /* KERN_PROC_H */