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 BeRTOS Kernel core (Process scheduler).
36 * \author Bernie Innocenti <bernie@codewiz.org>
38 * $WIZ$ module_name = "kernel"
39 * $WIZ$ module_configuration = "bertos/cfg/cfg_proc.h"
40 * $WIZ$ module_depends = "switch_ctx", "mtask"
41 * $WIZ$ module_supports = "not atmega103"
47 #include "cfg/cfg_proc.h"
48 #include "cfg/cfg_signal.h"
49 #include "cfg/cfg_monitor.h"
51 #include <struct/list.h> // Node, PriNode
53 #include <cfg/compiler.h>
55 #if CONFIG_KERN_PREEMPT
56 #include <cfg/debug.h> // ASSERT()
59 #include <cpu/types.h> // cpu_stack_t
60 #include <cpu/frame.h> // CPU_SAVED_REGS_CNT
63 * WARNING: struct Process is considered private, so its definition can change any time
64 * without notice. DO NOT RELY on any field defined here, use only the interface
67 * You have been warned.
69 typedef struct Process
72 PriNode link; /**< Link Process into scheduler lists */
74 Node link; /**< Link Process into scheduler lists */
76 cpu_stack_t *stack; /**< Per-process SP */
77 iptr_t user_data; /**< Custom data passed to the process */
79 #if CONFIG_KERN_SIGNALS
80 sigmask_t sig_wait; /**< Signals the process is waiting for */
81 sigmask_t sig_recv; /**< Received signals */
85 uint16_t flags; /**< Flags */
88 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR
89 cpu_stack_t *stack_base; /**< Base of process stack */
90 size_t stack_size; /**< Size of process stack */
93 /* The actual process entry point */
94 void (*user_entry)(void);
96 #if CONFIG_KERN_MONITOR
107 * Initialize the process subsystem (kernel).
108 * It must be called before using any process related function.
110 void proc_init(void);
112 struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
114 #if !CONFIG_KERN_MONITOR
116 * Create a new named process and schedules it for execution.
118 * When defining the stacksize take into account that you may want at least:
119 * \li save all the registers for each nested function call;
120 * \li have memory for the struct Process, which is positioned at the bottom
122 * \li have some memory for temporary variables inside called functions.
124 * The value given by KERN_MINSTACKSIZE is rather safe to use in the first place.
126 * \param entry Function that the process will execute.
127 * \param data Pointer to user data.
128 * \param size Length of the stack.
129 * \param stack Pointer to the memory area to be used as a stack.
131 * \return Process structure of new created process
132 * if successful, NULL otherwise.
134 #define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
136 #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
140 * Terminate the execution of the current process.
142 void proc_exit(void);
145 * Co-operative context switch.
147 * The process that calls this function will release the CPU before its cpu quantum
148 * expires, the scheduler will run to select the next process that will take control
150 * \note This function is available only if CONFIG_KERN is enabled
151 * \sa cpu_relax(), which is the recommended method to release the cpu.
153 void proc_yield(void);
155 void proc_rename(struct Process *proc, const char *name);
156 const char *proc_name(struct Process *proc);
157 const char *proc_currentName(void);
160 * Return a pointer to the user data of the current process.
162 * To obtain user data, just call this function inside the process. Remember to cast
163 * the returned pointer to the correct type.
164 * \return Pointer to the user data of the current process.
166 iptr_t proc_currentUserData(void);
168 int proc_testSetup(void);
169 int proc_testRun(void);
170 int proc_testTearDown(void);
173 * Return the context structure of the currently running process.
175 * The details of the Process structure are private to the scheduler.
176 * The address returned by this function is an opaque pointer that can
177 * be passed as an argument to other process-related functions.
179 INLINE struct Process *proc_current(void)
181 extern struct Process *current_process;
182 return current_process;
186 void proc_setPri(struct Process *proc, int pri);
188 INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
193 #if CONFIG_KERN_PREEMPT
196 * Disable preemptive task switching.
198 * The scheduler maintains a global nesting counter. Task switching is
199 * effectively re-enabled only when the number of calls to proc_permit()
200 * matches the number of calls to proc_forbid().
202 * \note Calling functions that could sleep while task switching is disabled
203 * is dangerous and unsupported.
205 * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
206 * very efficient locking primitive in simple but performance-critical
207 * situations. In all other cases, semaphores offer a more flexible and
208 * fine-grained locking primitive.
212 INLINE void proc_forbid(void)
214 extern cpu_atomic_t preempt_count;
216 * We don't need to protect the counter against other processes.
217 * The reason why is a bit subtle.
219 * If a process gets here, preempt_forbid_cnt can be either 0,
220 * or != 0. In the latter case, preemption is already disabled
221 * and no concurrency issues can occur.
223 * In the former case, we could be preempted just after reading the
224 * value 0 from memory, and a concurrent process might, in fact,
225 * bump the value of preempt_forbid_cnt under our nose!
227 * BUT: if this ever happens, then we won't get another chance to
228 * run until the other process calls proc_permit() to re-enable
229 * preemption. At this point, the value of preempt_forbid_cnt
230 * must be back to 0, and thus what we had originally read from
231 * memory happens to be valid.
233 * No matter how hard you think about it, and how complicated you
234 * make your scenario, the above holds true as long as
235 * "preempt_forbid_cnt != 0" means that no task switching is
241 * Make sure preempt_count is flushed to memory so the preemption
242 * softirq will see the correct value from now on.
248 * Re-enable preemptive task switching.
252 INLINE void proc_permit(void)
254 extern cpu_atomic_t preempt_count;
257 * This is to ensure any global state changed by the process gets
258 * flushed to memory before task switching is re-enabled.
261 /* No need to protect against interrupts here. */
262 ASSERT(preempt_count > 0);
265 * This ensures preempt_count is flushed to memory immediately so the
266 * preemption interrupt sees the correct value.
272 * \return true if preemptive task switching is allowed.
273 * \note This accessor is needed because preempt_count
274 * must be absoultely private.
276 INLINE bool proc_preemptAllowed(void)
278 extern cpu_atomic_t preempt_count;
279 return (preempt_count == 0);
281 #else /* CONFIG_KERN_PREEMPT */
282 #define proc_forbid() /* NOP */
283 #define proc_permit() /* NOP */
284 #define proc_preemptAllowed() (true)
285 #endif /* CONFIG_KERN_PREEMPT */
287 /** Deprecated, use the proc_preemptAllowed() macro. */
288 #define proc_allowed() proc_preemptAllowed()
291 * Execute a block of \a CODE atomically with respect to task scheduling.
293 #define PROC_ATOMIC(CODE) \
301 * Default stack size for each thread, in bytes.
303 * The goal here is to allow a minimal task to save all of its
304 * registers twice, plus push a maximum of 32 variables on the
305 * stack. We add also struct Process size since we save it into the process'
308 * The actual size computed by the default formula greatly depends on what
309 * options are active and on the architecture.
311 * Note that on most 16bit architectures, interrupts will also
312 * run on the stack of the currently running process. Nested
313 * interrupts will greatly increases the amount of stack space
314 * required per process. Use irqmanager to minimize stack
318 #if (ARCH & ARCH_EMUL)
319 /* We need a large stack because system libraries are bloated */
320 #define KERN_MINSTACKSIZE 65536
322 #if CONFIG_KERN_PREEMPT
324 * A preemptible kernel needs a larger stack compared to the
325 * cooperative case. A task can be interrupted anytime in each
326 * node of the call graph, at any level of depth. This may
327 * result in a higher stack consumption, to call the ISR, save
328 * the current user context and to execute the kernel
329 * preemption routines implemented as ISR prologue and
330 * epilogue. All these calls are nested into the process stack.
332 * So, to reduce the risk of stack overflow/underflow problems
333 * add a x2 to the portion stack reserved to the user process.
335 #define KERN_MINSTACKSIZE \
336 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
337 + 32 * sizeof(int) * 2)
339 #define KERN_MINSTACKSIZE \
340 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
342 #endif /* CONFIG_KERN_PREEMPT */
346 #ifndef CONFIG_KERN_MINSTACKSIZE
347 /* For backward compatibility */
348 #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
350 #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
354 * Utility macro to allocate a stack of size \a size.
356 * This macro define a static stack for one process and do
357 * check if given stack size is enough to run process.
358 * \note If you plan to use kprintf() and similar functions, you will need
359 * at least KERN_MINSTACKSIZE * 2 bytes.
361 * \param name Variable name for the stack.
362 * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
364 #define PROC_DEFINE_STACK(name, size) \
365 cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \
366 STATIC_ASSERT((size) >= KERN_MINSTACKSIZE);
368 /* Memory fill codes to help debugging */
369 #if CONFIG_KERN_MONITOR
370 #include <cpu/types.h>
371 #if (SIZEOF_CPUSTACK_T == 1)
372 /* 8bit cpu_stack_t */
373 #define CONFIG_KERN_STACKFILLCODE 0xA5
374 #define CONFIG_KERN_MEMFILLCODE 0xDB
375 #elif (SIZEOF_CPUSTACK_T == 2)
376 /* 16bit cpu_stack_t */
377 #define CONFIG_KERN_STACKFILLCODE 0xA5A5
378 #define CONFIG_KERN_MEMFILLCODE 0xDBDB
379 #elif (SIZEOF_CPUSTACK_T == 4)
380 /* 32bit cpu_stack_t */
381 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
382 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
383 #elif (SIZEOF_CPUSTACK_T == 8)
384 /* 64bit cpu_stack_t */
385 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
386 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
388 #error No cpu_stack_t size supported!
392 #endif /* KERN_PROC_H */