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", "coop"
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 | (ARCH & ARCH_EMUL)
89 cpu_stack_t *stack_base; /**< Base of process stack */
90 size_t stack_size; /**< Size of process stack */
93 #if CONFIG_KERN_PREEMPT
97 #if CONFIG_KERN_MONITOR
108 * Initialize the process subsystem (kernel).
109 * It must be called before using any process related function.
111 void proc_init(void);
114 * Create a new named process and schedules it for execution.
116 * When defining the stacksize take into account that you may want at least:
117 * \li save all the registers for each nested function call;
118 * \li have memory for the struct Process, which is positioned at the bottom
120 * \li have some memory for temporary variables inside called functions.
122 * The value given by CONFIG_KERN_MINSTACKSIZE is rather safe to use in the first place.
126 * proc_new(entry, data, stacksize, stack)
128 * is a more convenient way to create a process, as you don't have to specify
131 * \param name Name of the process (currently unused).
132 * \param entry Function that the process will execute.
133 * \param data Pointer to user data.
134 * \param stacksize Length of the stack.
135 * \param stack Pointer to the memory area to be used as a stack.
137 struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
139 #if !CONFIG_KERN_MONITOR
140 #define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
142 #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
146 * Terminate the execution of the current process.
148 void proc_exit(void);
151 * Co-operative context switch.
153 * The process that calls this function will release the CPU before its cpu quantum
154 * expires, the scheduler will run to select the next process that will take control
156 * \note This function is available only if CONFIG_KERN is enabled
157 * \sa cpu_relax(), which is the recommended method to release the cpu.
159 void proc_yield(void);
161 void proc_rename(struct Process *proc, const char *name);
162 const char *proc_name(struct Process *proc);
163 const char *proc_currentName(void);
166 * Return a pointer to the user data of the current process.
168 * To obtain user data, just call this function inside the process. Remember to cast
169 * the returned pointer to the correct type.
170 * \return Pointer to the user data of the current process.
172 iptr_t proc_currentUserData(void);
174 int proc_testSetup(void);
175 int proc_testRun(void);
176 int proc_testTearDown(void);
179 * Return the context structure of the currently running process.
181 * The details of the Process structure are private to the scheduler.
182 * The address returned by this function is an opaque pointer that can
183 * be passed as an argument to other process-related functions.
185 INLINE struct Process *proc_current(void)
187 extern struct Process *CurrentProcess;
188 return CurrentProcess;
192 void proc_setPri(struct Process *proc, int pri);
194 INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
200 * Disable preemptive task switching.
202 * The scheduler maintains a global nesting counter. Task switching is
203 * effectively re-enabled only when the number of calls to proc_permit()
204 * matches the number of calls to proc_forbid().
206 * \note Calling functions that could sleep while task switching is disabled
207 * is dangerous and unsupported.
209 * \note calling proc_forbid() from within an interrupt is illegal and
212 * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
213 * very efficient locking primitive in simple but performance-critical
214 * situations. In all other cases, semaphores offer a more flexible and
215 * fine-grained locking primitive.
219 INLINE void proc_forbid(void)
221 #if CONFIG_KERN_PREEMPT
222 extern cpu_atomic_t _preempt_forbid_cnt;
224 * We don't need to protect the counter against other processes.
225 * The reason why is a bit subtle.
227 * If a process gets here, preempt_forbid_cnt can be either 0,
228 * or != 0. In the latter case, preemption is already disabled
229 * and no concurrency issues can occur.
231 * In the former case, we could be preempted just after reading the
232 * value 0 from memory, and a concurrent process might, in fact,
233 * bump the value of preempt_forbid_cnt under our nose!
235 * BUT: if this ever happens, then we won't get another chance to
236 * run until the other process calls proc_permit() to re-enable
237 * preemption. At this point, the value of preempt_forbid_cnt
238 * must be back to 0, and thus what we had originally read from
239 * memory happens to be valid.
241 * No matter how hard you think about it, and how complicated you
242 * make your scenario, the above holds true as long as
243 * "preempt_forbid_cnt != 0" means that no task switching is
246 ++_preempt_forbid_cnt;
249 * Make sure _preempt_forbid_cnt is flushed to memory so the
250 * preemption softirq will see the correct value from now on.
257 * Re-enable preemptive task switching.
261 INLINE void proc_permit(void)
263 #if CONFIG_KERN_PREEMPT
266 * This is to ensure any global state changed by the process gets
267 * flushed to memory before task switching is re-enabled.
270 extern cpu_atomic_t _preempt_forbid_cnt;
271 /* No need to protect against interrupts here. */
272 ASSERT(_preempt_forbid_cnt != 0);
273 --_preempt_forbid_cnt;
276 * This ensures _preempt_forbid_cnt is flushed to memory immediately
277 * so the preemption interrupt sees the correct value.
285 * \return true if preemptive task switching is allowed.
286 * \note This accessor is needed because _preempt_forbid_cnt
287 * must be absoultely private.
289 INLINE bool proc_allowed(void)
291 #if CONFIG_KERN_PREEMPT
292 extern cpu_atomic_t _preempt_forbid_cnt;
293 return (_preempt_forbid_cnt == 0);
300 * Execute a block of \a CODE atomically with respect to task scheduling.
302 #define PROC_ATOMIC(CODE) \
310 * Default stack size for each thread, in bytes.
312 * The goal here is to allow a minimal task to save all of its
313 * registers twice, plus push a maximum of 32 variables on the
314 * stack. We add also struct Process size since we save it into the process'
317 * The actual size computed by the default formula greatly depends on what
318 * options are active and on the architecture.
320 * Note that on most 16bit architectures, interrupts will also
321 * run on the stack of the currently running process. Nested
322 * interrupts will greatly increases the amount of stack space
323 * required per process. Use irqmanager to minimize stack
327 #if (ARCH & ARCH_EMUL)
328 /* We need a large stack because system libraries are bloated */
329 #define KERN_MINSTACKSIZE 65536
331 #define KERN_MINSTACKSIZE \
332 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
336 #ifndef CONFIG_KERN_MINSTACKSIZE
337 /* For backward compatibility */
338 #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
340 #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
344 * Utility macro to allocate a stack of size \a size.
346 * This macro define a static stack for one process and do
347 * check if given stack size is enough to run process.
348 * \note If you plan to use kprintf() and similar functions, you will need
349 * at least KERN_MINSTACKSIZE * 2 bytes.
351 * \param name Variable name for the stack.
352 * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
354 #define PROC_DEFINE_STACK(name, size) \
355 STATIC_ASSERT((size) >= KERN_MINSTACKSIZE); \
356 cpu_stack_t name[(size) / sizeof(cpu_stack_t)];
358 /* Memory fill codes to help debugging */
359 #if CONFIG_KERN_MONITOR
360 #include <cpu/types.h>
361 #if (SIZEOF_CPUSTACK_T == 1)
362 /* 8bit cpu_stack_t */
363 #define CONFIG_KERN_STACKFILLCODE 0xA5
364 #define CONFIG_KERN_MEMFILLCODE 0xDB
365 #elif (SIZEOF_CPUSTACK_T == 2)
366 /* 16bit cpu_stack_t */
367 #define CONFIG_KERN_STACKFILLCODE 0xA5A5
368 #define CONFIG_KERN_MEMFILLCODE 0xDBDB
369 #elif (SIZEOF_CPUSTACK_T == 4)
370 /* 32bit cpu_stack_t */
371 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
372 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
373 #elif (SIZEOF_CPUSTACK_T == 8)
374 /* 64bit cpu_stack_t */
375 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
376 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
378 #error No cpu_stack_t size supported!
382 #endif /* KERN_PROC_H */