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
107 #include <kern/signal.h>
110 * WARNING: struct Process is considered private, so its definition can change any time
111 * without notice. DO NOT RELY on any field defined here, use only the interface
114 * You have been warned.
116 typedef struct Process
119 PriNode link; /**< Link Process into scheduler lists */
121 Node link; /**< Link Process into scheduler lists */
123 cpu_stack_t *stack; /**< Per-process SP */
124 iptr_t user_data; /**< Custom data passed to the process */
126 #if CONFIG_KERN_SIGNALS
131 uint16_t flags; /**< Flags */
134 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR
135 cpu_stack_t *stack_base; /**< Base of process stack */
136 size_t stack_size; /**< Size of process stack */
139 /* The actual process entry point */
140 void (*user_entry)(void);
142 #if CONFIG_KERN_MONITOR
153 * Initialize the process subsystem (kernel).
154 * It must be called before using any process related function.
156 void proc_init(void);
158 struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
160 #if !CONFIG_KERN_MONITOR
162 * Create a new named process and schedules it for execution.
164 * When defining the stacksize take into account that you may want at least:
165 * \li save all the registers for each nested function call;
166 * \li have memory for the struct Process, which is positioned at the bottom
168 * \li have some memory for temporary variables inside called functions.
170 * The value given by KERN_MINSTACKSIZE is rather safe to use in the first place.
172 * \param entry Function that the process will execute.
173 * \param data Pointer to user data.
174 * \param size Length of the stack.
175 * \param stack Pointer to the memory area to be used as a stack.
177 * \return Process structure of new created process
178 * if successful, NULL otherwise.
180 #define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
182 #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
186 * Terminate the execution of the current process.
188 void proc_exit(void);
191 * Public scheduling class methods.
193 void proc_yield(void);
195 #if CONFIG_KERN_PREEMPT
196 bool proc_needPreempt(void);
197 void proc_preempt(void);
199 INLINE bool proc_needPreempt(void)
204 INLINE void proc_preempt(void)
209 void proc_rename(struct Process *proc, const char *name);
210 const char *proc_name(struct Process *proc);
211 const char *proc_currentName(void);
214 * Return a pointer to the user data of the current process.
216 * To obtain user data, just call this function inside the process. Remember to cast
217 * the returned pointer to the correct type.
218 * \return Pointer to the user data of the current process.
220 INLINE iptr_t proc_currentUserData(void)
222 extern struct Process *current_process;
223 return current_process->user_data;
226 int proc_testSetup(void);
227 int proc_testRun(void);
228 int proc_testTearDown(void);
231 * Return the context structure of the currently running process.
233 * The details of the Process structure are private to the scheduler.
234 * The address returned by this function is an opaque pointer that can
235 * be passed as an argument to other process-related functions.
237 INLINE struct Process *proc_current(void)
239 extern struct Process *current_process;
240 return current_process;
244 void proc_setPri(struct Process *proc, int pri);
246 INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
251 #if CONFIG_KERN_PREEMPT
254 * Disable preemptive task switching.
256 * The scheduler maintains a global nesting counter. Task switching is
257 * effectively re-enabled only when the number of calls to proc_permit()
258 * matches the number of calls to proc_forbid().
260 * \note Calling functions that could sleep while task switching is disabled
261 * is dangerous and unsupported.
263 * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
264 * very efficient locking primitive in simple but performance-critical
265 * situations. In all other cases, semaphores offer a more flexible and
266 * fine-grained locking primitive.
270 INLINE void proc_forbid(void)
272 extern cpu_atomic_t preempt_count;
274 * We don't need to protect the counter against other processes.
275 * The reason why is a bit subtle.
277 * If a process gets here, preempt_forbid_cnt can be either 0,
278 * or != 0. In the latter case, preemption is already disabled
279 * and no concurrency issues can occur.
281 * In the former case, we could be preempted just after reading the
282 * value 0 from memory, and a concurrent process might, in fact,
283 * bump the value of preempt_forbid_cnt under our nose!
285 * BUT: if this ever happens, then we won't get another chance to
286 * run until the other process calls proc_permit() to re-enable
287 * preemption. At this point, the value of preempt_forbid_cnt
288 * must be back to 0, and thus what we had originally read from
289 * memory happens to be valid.
291 * No matter how hard you think about it, and how complicated you
292 * make your scenario, the above holds true as long as
293 * "preempt_forbid_cnt != 0" means that no task switching is
299 * Make sure preempt_count is flushed to memory so the preemption
300 * softirq will see the correct value from now on.
306 * Re-enable preemptive task switching.
310 INLINE void proc_permit(void)
312 extern cpu_atomic_t preempt_count;
315 * This is to ensure any global state changed by the process gets
316 * flushed to memory before task switching is re-enabled.
319 /* No need to protect against interrupts here. */
320 ASSERT(preempt_count > 0);
323 * This ensures preempt_count is flushed to memory immediately so the
324 * preemption interrupt sees the correct value.
330 * \return true if preemptive task switching is allowed.
331 * \note This accessor is needed because preempt_count
332 * must be absoultely private.
334 INLINE bool proc_preemptAllowed(void)
336 extern cpu_atomic_t preempt_count;
337 return (preempt_count == 0);
339 #else /* CONFIG_KERN_PREEMPT */
340 #define proc_forbid() /* NOP */
341 #define proc_permit() /* NOP */
342 #define proc_preemptAllowed() (true)
343 #endif /* CONFIG_KERN_PREEMPT */
345 /** Deprecated, use the proc_preemptAllowed() macro. */
346 #define proc_allowed() proc_preemptAllowed()
349 * Execute a block of \a CODE atomically with respect to task scheduling.
351 #define PROC_ATOMIC(CODE) \
359 * Default stack size for each thread, in bytes.
361 * The goal here is to allow a minimal task to save all of its
362 * registers twice, plus push a maximum of 32 variables on the
363 * stack. We add also struct Process size since we save it into the process'
366 * The actual size computed by the default formula greatly depends on what
367 * options are active and on the architecture.
369 * Note that on most 16bit architectures, interrupts will also
370 * run on the stack of the currently running process. Nested
371 * interrupts will greatly increases the amount of stack space
372 * required per process. Use irqmanager to minimize stack
376 #if (ARCH & ARCH_EMUL)
377 /* We need a large stack because system libraries are bloated */
378 #define KERN_MINSTACKSIZE 65536
380 #if CONFIG_KERN_PREEMPT
382 * A preemptible kernel needs a larger stack compared to the
383 * cooperative case. A task can be interrupted anytime in each
384 * node of the call graph, at any level of depth. This may
385 * result in a higher stack consumption, to call the ISR, save
386 * the current user context and to execute the kernel
387 * preemption routines implemented as ISR prologue and
388 * epilogue. All these calls are nested into the process stack.
390 * So, to reduce the risk of stack overflow/underflow problems
391 * add a x2 to the portion stack reserved to the user process.
393 #define KERN_MINSTACKSIZE \
394 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
395 + 32 * sizeof(int) * 2)
397 #define KERN_MINSTACKSIZE \
398 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
400 #endif /* CONFIG_KERN_PREEMPT */
404 #ifndef CONFIG_KERN_MINSTACKSIZE
405 /* For backward compatibility */
406 #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
408 #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
412 * Utility macro to allocate a stack of size \a size.
414 * This macro define a static stack for one process and do
415 * check if given stack size is enough to run process.
416 * \note If you plan to use kprintf() and similar functions, you will need
417 * at least KERN_MINSTACKSIZE * 2 bytes.
419 * \param name Variable name for the stack.
420 * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
422 #define PROC_DEFINE_STACK(name, size) \
423 cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \
424 STATIC_ASSERT((size) >= KERN_MINSTACKSIZE);
426 /* Memory fill codes to help debugging */
427 #if CONFIG_KERN_MONITOR
428 #include <cpu/types.h>
429 #if (SIZEOF_CPUSTACK_T == 1)
430 /* 8bit cpu_stack_t */
431 #define CONFIG_KERN_STACKFILLCODE 0xA5
432 #define CONFIG_KERN_MEMFILLCODE 0xDB
433 #elif (SIZEOF_CPUSTACK_T == 2)
434 /* 16bit cpu_stack_t */
435 #define CONFIG_KERN_STACKFILLCODE 0xA5A5
436 #define CONFIG_KERN_MEMFILLCODE 0xDBDB
437 #elif (SIZEOF_CPUSTACK_T == 4)
438 /* 32bit cpu_stack_t */
439 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
440 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
441 #elif (SIZEOF_CPUSTACK_T == 8)
442 /* 64bit cpu_stack_t */
443 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
444 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
446 #error No cpu_stack_t size supported!
449 /** \} */ //defgroup kern_proc
451 #endif /* KERN_PROC_H */