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);
153 * Dummy function that defines unimplemented scheduler class methods.
155 INLINE void __proc_noop(void)
159 #if CONFIG_KERN_PREEMPT
161 * Preemptive scheduler public methods.
163 #define preempt_yield proc_yield
164 #define preempt_needPreempt proc_needPreempt
165 #define preempt_preempt proc_preempt
167 * Preemptive scheduler: private methods.
169 #define preempt_switch proc_switch
172 * Co-operative scheduler: public methods.
174 #define coop_yield proc_yield
175 #define proc_needPreempt __proc_noop
176 #define proc_preempt __proc_noop
178 * Co-operative scheduler: private methods.
180 #define coop_switch proc_switch
183 void proc_rename(struct Process *proc, const char *name);
184 const char *proc_name(struct Process *proc);
185 const char *proc_currentName(void);
188 * Return a pointer to the user data of the current process.
190 * To obtain user data, just call this function inside the process. Remember to cast
191 * the returned pointer to the correct type.
192 * \return Pointer to the user data of the current process.
194 iptr_t proc_currentUserData(void);
196 int proc_testSetup(void);
197 int proc_testRun(void);
198 int proc_testTearDown(void);
201 * Return the context structure of the currently running process.
203 * The details of the Process structure are private to the scheduler.
204 * The address returned by this function is an opaque pointer that can
205 * be passed as an argument to other process-related functions.
207 INLINE struct Process *proc_current(void)
209 extern struct Process *current_process;
210 return current_process;
214 void proc_setPri(struct Process *proc, int pri);
216 INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
221 #if CONFIG_KERN_PREEMPT
224 * Disable preemptive task switching.
226 * The scheduler maintains a global nesting counter. Task switching is
227 * effectively re-enabled only when the number of calls to proc_permit()
228 * matches the number of calls to proc_forbid().
230 * \note Calling functions that could sleep while task switching is disabled
231 * is dangerous and unsupported.
233 * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
234 * very efficient locking primitive in simple but performance-critical
235 * situations. In all other cases, semaphores offer a more flexible and
236 * fine-grained locking primitive.
240 INLINE void proc_forbid(void)
242 extern cpu_atomic_t preempt_count;
244 * We don't need to protect the counter against other processes.
245 * The reason why is a bit subtle.
247 * If a process gets here, preempt_forbid_cnt can be either 0,
248 * or != 0. In the latter case, preemption is already disabled
249 * and no concurrency issues can occur.
251 * In the former case, we could be preempted just after reading the
252 * value 0 from memory, and a concurrent process might, in fact,
253 * bump the value of preempt_forbid_cnt under our nose!
255 * BUT: if this ever happens, then we won't get another chance to
256 * run until the other process calls proc_permit() to re-enable
257 * preemption. At this point, the value of preempt_forbid_cnt
258 * must be back to 0, and thus what we had originally read from
259 * memory happens to be valid.
261 * No matter how hard you think about it, and how complicated you
262 * make your scenario, the above holds true as long as
263 * "preempt_forbid_cnt != 0" means that no task switching is
269 * Make sure preempt_count is flushed to memory so the preemption
270 * softirq will see the correct value from now on.
276 * Re-enable preemptive task switching.
280 INLINE void proc_permit(void)
282 extern cpu_atomic_t preempt_count;
285 * This is to ensure any global state changed by the process gets
286 * flushed to memory before task switching is re-enabled.
289 /* No need to protect against interrupts here. */
290 ASSERT(preempt_count > 0);
293 * This ensures preempt_count is flushed to memory immediately so the
294 * preemption interrupt sees the correct value.
300 * \return true if preemptive task switching is allowed.
301 * \note This accessor is needed because preempt_count
302 * must be absoultely private.
304 INLINE bool proc_preemptAllowed(void)
306 extern cpu_atomic_t preempt_count;
307 return (preempt_count == 0);
309 #else /* CONFIG_KERN_PREEMPT */
310 #define proc_forbid() /* NOP */
311 #define proc_permit() /* NOP */
312 #define proc_preemptAllowed() (true)
313 #endif /* CONFIG_KERN_PREEMPT */
315 /** Deprecated, use the proc_preemptAllowed() macro. */
316 #define proc_allowed() proc_preemptAllowed()
319 * Execute a block of \a CODE atomically with respect to task scheduling.
321 #define PROC_ATOMIC(CODE) \
329 * Default stack size for each thread, in bytes.
331 * The goal here is to allow a minimal task to save all of its
332 * registers twice, plus push a maximum of 32 variables on the
333 * stack. We add also struct Process size since we save it into the process'
336 * The actual size computed by the default formula greatly depends on what
337 * options are active and on the architecture.
339 * Note that on most 16bit architectures, interrupts will also
340 * run on the stack of the currently running process. Nested
341 * interrupts will greatly increases the amount of stack space
342 * required per process. Use irqmanager to minimize stack
346 #if (ARCH & ARCH_EMUL)
347 /* We need a large stack because system libraries are bloated */
348 #define KERN_MINSTACKSIZE 65536
350 #if CONFIG_KERN_PREEMPT
352 * A preemptible kernel needs a larger stack compared to the
353 * cooperative case. A task can be interrupted anytime in each
354 * node of the call graph, at any level of depth. This may
355 * result in a higher stack consumption, to call the ISR, save
356 * the current user context and to execute the kernel
357 * preemption routines implemented as ISR prologue and
358 * epilogue. All these calls are nested into the process stack.
360 * So, to reduce the risk of stack overflow/underflow problems
361 * add a x2 to the portion stack reserved to the user process.
363 #define KERN_MINSTACKSIZE \
364 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
365 + 32 * sizeof(int) * 2)
367 #define KERN_MINSTACKSIZE \
368 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
370 #endif /* CONFIG_KERN_PREEMPT */
374 #ifndef CONFIG_KERN_MINSTACKSIZE
375 /* For backward compatibility */
376 #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
378 #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
382 * Utility macro to allocate a stack of size \a size.
384 * This macro define a static stack for one process and do
385 * check if given stack size is enough to run process.
386 * \note If you plan to use kprintf() and similar functions, you will need
387 * at least KERN_MINSTACKSIZE * 2 bytes.
389 * \param name Variable name for the stack.
390 * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
392 #define PROC_DEFINE_STACK(name, size) \
393 cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \
394 STATIC_ASSERT((size) >= KERN_MINSTACKSIZE);
396 /* Memory fill codes to help debugging */
397 #if CONFIG_KERN_MONITOR
398 #include <cpu/types.h>
399 #if (SIZEOF_CPUSTACK_T == 1)
400 /* 8bit cpu_stack_t */
401 #define CONFIG_KERN_STACKFILLCODE 0xA5
402 #define CONFIG_KERN_MEMFILLCODE 0xDB
403 #elif (SIZEOF_CPUSTACK_T == 2)
404 /* 16bit cpu_stack_t */
405 #define CONFIG_KERN_STACKFILLCODE 0xA5A5
406 #define CONFIG_KERN_MEMFILLCODE 0xDBDB
407 #elif (SIZEOF_CPUSTACK_T == 4)
408 /* 32bit cpu_stack_t */
409 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
410 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
411 #elif (SIZEOF_CPUSTACK_T == 8)
412 /* 64bit cpu_stack_t */
413 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
414 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
416 #error No cpu_stack_t size supported!
420 #endif /* KERN_PROC_H */