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", "preempt"
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()
57 #include <kern/preempt.h>
60 #include <cpu/types.h> // cpu_stack_t
61 #include <cpu/frame.h> // CPU_SAVED_REGS_CNT
64 * WARNING: struct Process is considered private, so its definition can change any time
65 * without notice. DO NOT RELY on any field defined here, use only the interface
68 * You have been warned.
70 typedef struct Process
73 PriNode link; /**< Link Process into scheduler lists */
75 Node link; /**< Link Process into scheduler lists */
77 cpu_stack_t *stack; /**< Per-process SP */
78 iptr_t user_data; /**< Custom data passed to the process */
80 #if CONFIG_KERN_SIGNALS
81 sigmask_t sig_wait; /**< Signals the process is waiting for */
82 sigmask_t sig_recv; /**< Received signals */
86 uint16_t flags; /**< Flags */
89 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR
90 cpu_stack_t *stack_base; /**< Base of process stack */
91 size_t stack_size; /**< Size of process stack */
94 /* The actual process entry point */
95 void (*user_entry)(void);
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);
113 struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
115 #if !CONFIG_KERN_MONITOR
117 * Create a new named process and schedules it for execution.
119 * When defining the stacksize take into account that you may want at least:
120 * \li save all the registers for each nested function call;
121 * \li have memory for the struct Process, which is positioned at the bottom
123 * \li have some memory for temporary variables inside called functions.
125 * The value given by KERN_MINSTACKSIZE is rather safe to use in the first place.
127 * \param entry Function that the process will execute.
128 * \param data Pointer to user data.
129 * \param size Length of the stack.
130 * \param stack Pointer to the memory area to be used as a stack.
132 * \return Process structure of new created process
133 * if successful, NULL otherwise.
135 #define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
137 #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
141 * Terminate the execution of the current process.
143 void proc_exit(void);
146 * Public scheduling class methods.
148 void proc_yield(void);
149 void proc_preempt(void);
150 int proc_needPreempt(void);
151 void proc_wakeup(Process *proc);
154 * Dummy function that defines unimplemented scheduler class methods.
156 INLINE void __proc_noop(void)
160 #if CONFIG_KERN_PREEMPT
162 * Preemptive scheduler public methods.
164 #define preempt_yield proc_yield
165 #define preempt_needPreempt proc_needPreempt
166 #define preempt_preempt proc_preempt
168 * Preemptive scheduler: private methods.
170 #define preempt_switch proc_switch
171 #define preempt_wakeup proc_wakeup
174 * Co-operative scheduler: public methods.
176 #define coop_yield proc_yield
177 #define proc_needPreempt __proc_noop
178 #define proc_preempt __proc_noop
180 * Co-operative scheduler: private methods.
182 #define coop_switch proc_switch
183 #define coop_wakeup proc_wakeup
186 void proc_rename(struct Process *proc, const char *name);
187 const char *proc_name(struct Process *proc);
188 const char *proc_currentName(void);
191 * Return a pointer to the user data of the current process.
193 * To obtain user data, just call this function inside the process. Remember to cast
194 * the returned pointer to the correct type.
195 * \return Pointer to the user data of the current process.
197 INLINE iptr_t proc_currentUserData(void)
199 extern struct Process *current_process;
200 return current_process->user_data;
203 int proc_testSetup(void);
204 int proc_testRun(void);
205 int proc_testTearDown(void);
208 * Return the context structure of the currently running process.
210 * The details of the Process structure are private to the scheduler.
211 * The address returned by this function is an opaque pointer that can
212 * be passed as an argument to other process-related functions.
214 INLINE struct Process *proc_current(void)
216 extern struct Process *current_process;
217 return current_process;
221 void proc_setPri(struct Process *proc, int pri);
223 INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
228 #if CONFIG_KERN_PREEMPT
231 * Disable preemptive task switching.
233 * The scheduler maintains a global nesting counter. Task switching is
234 * effectively re-enabled only when the number of calls to proc_permit()
235 * matches the number of calls to proc_forbid().
237 * \note Calling functions that could sleep while task switching is disabled
238 * is dangerous and unsupported.
240 * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
241 * very efficient locking primitive in simple but performance-critical
242 * situations. In all other cases, semaphores offer a more flexible and
243 * fine-grained locking primitive.
247 INLINE void proc_forbid(void)
249 extern cpu_atomic_t preempt_count;
251 * We don't need to protect the counter against other processes.
252 * The reason why is a bit subtle.
254 * If a process gets here, preempt_forbid_cnt can be either 0,
255 * or != 0. In the latter case, preemption is already disabled
256 * and no concurrency issues can occur.
258 * In the former case, we could be preempted just after reading the
259 * value 0 from memory, and a concurrent process might, in fact,
260 * bump the value of preempt_forbid_cnt under our nose!
262 * BUT: if this ever happens, then we won't get another chance to
263 * run until the other process calls proc_permit() to re-enable
264 * preemption. At this point, the value of preempt_forbid_cnt
265 * must be back to 0, and thus what we had originally read from
266 * memory happens to be valid.
268 * No matter how hard you think about it, and how complicated you
269 * make your scenario, the above holds true as long as
270 * "preempt_forbid_cnt != 0" means that no task switching is
276 * Make sure preempt_count is flushed to memory so the preemption
277 * softirq will see the correct value from now on.
283 * Re-enable preemptive task switching.
287 INLINE void proc_permit(void)
289 extern cpu_atomic_t preempt_count;
292 * This is to ensure any global state changed by the process gets
293 * flushed to memory before task switching is re-enabled.
296 /* No need to protect against interrupts here. */
297 ASSERT(preempt_count > 0);
300 * This ensures preempt_count is flushed to memory immediately so the
301 * preemption interrupt sees the correct value.
307 * \return true if preemptive task switching is allowed.
308 * \note This accessor is needed because preempt_count
309 * must be absoultely private.
311 INLINE bool proc_preemptAllowed(void)
313 extern cpu_atomic_t preempt_count;
314 return (preempt_count == 0);
316 #else /* CONFIG_KERN_PREEMPT */
317 #define proc_forbid() /* NOP */
318 #define proc_permit() /* NOP */
319 #define proc_preemptAllowed() (true)
320 #endif /* CONFIG_KERN_PREEMPT */
322 /** Deprecated, use the proc_preemptAllowed() macro. */
323 #define proc_allowed() proc_preemptAllowed()
326 * Execute a block of \a CODE atomically with respect to task scheduling.
328 #define PROC_ATOMIC(CODE) \
336 * Default stack size for each thread, in bytes.
338 * The goal here is to allow a minimal task to save all of its
339 * registers twice, plus push a maximum of 32 variables on the
340 * stack. We add also struct Process size since we save it into the process'
343 * The actual size computed by the default formula greatly depends on what
344 * options are active and on the architecture.
346 * Note that on most 16bit architectures, interrupts will also
347 * run on the stack of the currently running process. Nested
348 * interrupts will greatly increases the amount of stack space
349 * required per process. Use irqmanager to minimize stack
353 #if (ARCH & ARCH_EMUL)
354 /* We need a large stack because system libraries are bloated */
355 #define KERN_MINSTACKSIZE 65536
357 #if CONFIG_KERN_PREEMPT
359 * A preemptible kernel needs a larger stack compared to the
360 * cooperative case. A task can be interrupted anytime in each
361 * node of the call graph, at any level of depth. This may
362 * result in a higher stack consumption, to call the ISR, save
363 * the current user context and to execute the kernel
364 * preemption routines implemented as ISR prologue and
365 * epilogue. All these calls are nested into the process stack.
367 * So, to reduce the risk of stack overflow/underflow problems
368 * add a x2 to the portion stack reserved to the user process.
370 #define KERN_MINSTACKSIZE \
371 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
372 + 32 * sizeof(int) * 2)
374 #define KERN_MINSTACKSIZE \
375 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
377 #endif /* CONFIG_KERN_PREEMPT */
381 #ifndef CONFIG_KERN_MINSTACKSIZE
382 /* For backward compatibility */
383 #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
385 #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
389 * Utility macro to allocate a stack of size \a size.
391 * This macro define a static stack for one process and do
392 * check if given stack size is enough to run process.
393 * \note If you plan to use kprintf() and similar functions, you will need
394 * at least KERN_MINSTACKSIZE * 2 bytes.
396 * \param name Variable name for the stack.
397 * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
399 #define PROC_DEFINE_STACK(name, size) \
400 cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \
401 STATIC_ASSERT((size) >= KERN_MINSTACKSIZE);
403 /* Memory fill codes to help debugging */
404 #if CONFIG_KERN_MONITOR
405 #include <cpu/types.h>
406 #if (SIZEOF_CPUSTACK_T == 1)
407 /* 8bit cpu_stack_t */
408 #define CONFIG_KERN_STACKFILLCODE 0xA5
409 #define CONFIG_KERN_MEMFILLCODE 0xDB
410 #elif (SIZEOF_CPUSTACK_T == 2)
411 /* 16bit cpu_stack_t */
412 #define CONFIG_KERN_STACKFILLCODE 0xA5A5
413 #define CONFIG_KERN_MEMFILLCODE 0xDBDB
414 #elif (SIZEOF_CPUSTACK_T == 4)
415 /* 32bit cpu_stack_t */
416 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
417 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
418 #elif (SIZEOF_CPUSTACK_T == 8)
419 /* 64bit cpu_stack_t */
420 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
421 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
423 #error No cpu_stack_t size supported!
427 #endif /* KERN_PROC_H */