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).
35 * \author Bernie Innocenti <bernie@codewiz.org>
37 * $WIZ$ module_name = "kernel"
38 * $WIZ$ module_configuration = "bertos/cfg/cfg_proc.h"
39 * $WIZ$ module_depends = "switch_ctx"
40 * $WIZ$ module_supports = "not atmega103"
46 #include "cfg/cfg_proc.h"
47 #include "cfg/cfg_signal.h"
48 #include "cfg/cfg_monitor.h"
50 #include <struct/list.h> // Node, PriNode
52 #include <cfg/compiler.h>
53 #include <cfg/debug.h> // ASSERT()
55 #include <cpu/types.h> // cpu_stack_t
56 #include <cpu/frame.h> // CPU_SAVED_REGS_CNT
59 * WARNING: struct Process is considered private, so its definition can change any time
60 * without notice. DO NOT RELY on any field defined here, use only the interface
63 * You have been warned.
65 typedef struct Process
68 PriNode link; /**< Link Process into scheduler lists */
70 Node link; /**< Link Process into scheduler lists */
72 cpu_stack_t *stack; /**< Per-process SP */
73 iptr_t user_data; /**< Custom data passed to the process */
75 #if CONFIG_KERN_SIGNALS
76 sigmask_t sig_wait; /**< Signals the process is waiting for */
77 sigmask_t sig_recv; /**< Received signals */
81 uint16_t flags; /**< Flags */
84 #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR
85 cpu_stack_t *stack_base; /**< Base of process stack */
86 size_t stack_size; /**< Size of process stack */
89 /* The actual process entry point */
90 void (*user_entry)(void);
92 #if CONFIG_KERN_MONITOR
103 * Initialize the process subsystem (kernel).
104 * It must be called before using any process related function.
106 void proc_init(void);
108 struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
110 #if !CONFIG_KERN_MONITOR
112 * Create a new named process and schedules it for execution.
114 * When defining the stacksize take into account that you may want at least:
115 * \li save all the registers for each nested function call;
116 * \li have memory for the struct Process, which is positioned at the bottom
118 * \li have some memory for temporary variables inside called functions.
120 * The value given by KERN_MINSTACKSIZE is rather safe to use in the first place.
122 * \param entry Function that the process will execute.
123 * \param data Pointer to user data.
124 * \param size Length of the stack.
125 * \param stack Pointer to the memory area to be used as a stack.
127 * \return Process structure of new created process
128 * if successful, NULL otherwise.
130 #define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
132 #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
136 * Terminate the execution of the current process.
138 void proc_exit(void);
141 * Public scheduling class methods.
143 void proc_yield(void);
145 #if CONFIG_KERN_PREEMPT
146 bool proc_needPreempt(void);
147 void proc_preempt(void);
149 INLINE bool proc_needPreempt(void)
154 INLINE void proc_preempt(void)
159 void proc_rename(struct Process *proc, const char *name);
160 const char *proc_name(struct Process *proc);
161 const char *proc_currentName(void);
164 * Return a pointer to the user data of the current process.
166 * To obtain user data, just call this function inside the process. Remember to cast
167 * the returned pointer to the correct type.
168 * \return Pointer to the user data of the current process.
170 INLINE iptr_t proc_currentUserData(void)
172 extern struct Process *current_process;
173 return current_process->user_data;
176 int proc_testSetup(void);
177 int proc_testRun(void);
178 int proc_testTearDown(void);
181 * Return the context structure of the currently running process.
183 * The details of the Process structure are private to the scheduler.
184 * The address returned by this function is an opaque pointer that can
185 * be passed as an argument to other process-related functions.
187 INLINE struct Process *proc_current(void)
189 extern struct Process *current_process;
190 return current_process;
194 void proc_setPri(struct Process *proc, int pri);
196 INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
201 #if CONFIG_KERN_PREEMPT
204 * Disable preemptive task switching.
206 * The scheduler maintains a global nesting counter. Task switching is
207 * effectively re-enabled only when the number of calls to proc_permit()
208 * matches the number of calls to proc_forbid().
210 * \note Calling functions that could sleep while task switching is disabled
211 * is dangerous and unsupported.
213 * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
214 * very efficient locking primitive in simple but performance-critical
215 * situations. In all other cases, semaphores offer a more flexible and
216 * fine-grained locking primitive.
220 INLINE void proc_forbid(void)
222 extern cpu_atomic_t preempt_count;
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
249 * Make sure preempt_count is flushed to memory so the preemption
250 * softirq will see the correct value from now on.
256 * Re-enable preemptive task switching.
260 INLINE void proc_permit(void)
262 extern cpu_atomic_t preempt_count;
265 * This is to ensure any global state changed by the process gets
266 * flushed to memory before task switching is re-enabled.
269 /* No need to protect against interrupts here. */
270 ASSERT(preempt_count > 0);
273 * This ensures preempt_count is flushed to memory immediately so the
274 * preemption interrupt sees the correct value.
280 * \return true if preemptive task switching is allowed.
281 * \note This accessor is needed because preempt_count
282 * must be absoultely private.
284 INLINE bool proc_preemptAllowed(void)
286 extern cpu_atomic_t preempt_count;
287 return (preempt_count == 0);
289 #else /* CONFIG_KERN_PREEMPT */
290 #define proc_forbid() /* NOP */
291 #define proc_permit() /* NOP */
292 #define proc_preemptAllowed() (true)
293 #endif /* CONFIG_KERN_PREEMPT */
295 /** Deprecated, use the proc_preemptAllowed() macro. */
296 #define proc_allowed() proc_preemptAllowed()
299 * Execute a block of \a CODE atomically with respect to task scheduling.
301 #define PROC_ATOMIC(CODE) \
309 * Default stack size for each thread, in bytes.
311 * The goal here is to allow a minimal task to save all of its
312 * registers twice, plus push a maximum of 32 variables on the
313 * stack. We add also struct Process size since we save it into the process'
316 * The actual size computed by the default formula greatly depends on what
317 * options are active and on the architecture.
319 * Note that on most 16bit architectures, interrupts will also
320 * run on the stack of the currently running process. Nested
321 * interrupts will greatly increases the amount of stack space
322 * required per process. Use irqmanager to minimize stack
326 #if (ARCH & ARCH_EMUL)
327 /* We need a large stack because system libraries are bloated */
328 #define KERN_MINSTACKSIZE 65536
330 #if CONFIG_KERN_PREEMPT
332 * A preemptible kernel needs a larger stack compared to the
333 * cooperative case. A task can be interrupted anytime in each
334 * node of the call graph, at any level of depth. This may
335 * result in a higher stack consumption, to call the ISR, save
336 * the current user context and to execute the kernel
337 * preemption routines implemented as ISR prologue and
338 * epilogue. All these calls are nested into the process stack.
340 * So, to reduce the risk of stack overflow/underflow problems
341 * add a x2 to the portion stack reserved to the user process.
343 #define KERN_MINSTACKSIZE \
344 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
345 + 32 * sizeof(int) * 2)
347 #define KERN_MINSTACKSIZE \
348 (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
350 #endif /* CONFIG_KERN_PREEMPT */
354 #ifndef CONFIG_KERN_MINSTACKSIZE
355 /* For backward compatibility */
356 #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
358 #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
362 * Utility macro to allocate a stack of size \a size.
364 * This macro define a static stack for one process and do
365 * check if given stack size is enough to run process.
366 * \note If you plan to use kprintf() and similar functions, you will need
367 * at least KERN_MINSTACKSIZE * 2 bytes.
369 * \param name Variable name for the stack.
370 * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
372 #define PROC_DEFINE_STACK(name, size) \
373 cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \
374 STATIC_ASSERT((size) >= KERN_MINSTACKSIZE);
376 /* Memory fill codes to help debugging */
377 #if CONFIG_KERN_MONITOR
378 #include <cpu/types.h>
379 #if (SIZEOF_CPUSTACK_T == 1)
380 /* 8bit cpu_stack_t */
381 #define CONFIG_KERN_STACKFILLCODE 0xA5
382 #define CONFIG_KERN_MEMFILLCODE 0xDB
383 #elif (SIZEOF_CPUSTACK_T == 2)
384 /* 16bit cpu_stack_t */
385 #define CONFIG_KERN_STACKFILLCODE 0xA5A5
386 #define CONFIG_KERN_MEMFILLCODE 0xDBDB
387 #elif (SIZEOF_CPUSTACK_T == 4)
388 /* 32bit cpu_stack_t */
389 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
390 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
391 #elif (SIZEOF_CPUSTACK_T == 8)
392 /* 64bit cpu_stack_t */
393 #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
394 #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
396 #error No cpu_stack_t size supported!
400 #endif /* KERN_PROC_H */