/** * \file * * * \defgroup kern_proc Process (Threads) management * \ingroup kern * \{ * * \brief BeRTOS Kernel core (Process scheduler). * * This is the core kernel module. It allows you to create new processes * (which are called \b threads in other systems) and set the priority of * each process. * * A process needs a work area (called \b stack) to run. To create a process, * you need to declare a stack area, then create the process. * You may also pass NULL for the stack area, if you have enabled kernel heap: * in this case the stack will be automatically allocated. * * Example: * \code * PROC_DEFINE_STACK(stack1, 200); * * void NORETURN proc1_run(void) * { * while (1) * { * LOG_INFO("I'm alive!\n"); * timer_delay(1000); * } * } * * * int main() * { * Process *p1 = proc_new(proc1_run, NULL, stack1, sizeof(stack1)); * // here the process is already running * proc_setPri(p1, 2); * // ... * } * \endcode * * The Process struct must be regarded as an opaque data type, do not access * any of its members directly. * * The entry point function should be declared as NORETURN, because it will * remove a warning and enable compiler optimizations. * * You can temporarily disable preemption calling proc_forbid(); remember * to enable it again calling proc_permit(). * * \note You should hardly need to manually release the CPU; however you * can do it using the cpu_relax() function. It is illegal to release * the CPU with preemption disabled. * * \author Bernie Innocenti * * $WIZ$ module_name = "kernel" * $WIZ$ module_configuration = "bertos/cfg/cfg_proc.h" * $WIZ$ module_depends = "switch_ctx" * $WIZ$ module_supports = "not atmega103" */ #ifndef KERN_PROC_H #define KERN_PROC_H #include "cfg/cfg_proc.h" #include "cfg/cfg_signal.h" #include "cfg/cfg_monitor.h" #include "sem.h" #include // Node, PriNode #include #include // ASSERT() #include // cpu_stack_t #include // CPU_SAVED_REGS_CNT /* The following silents warnings on nightly tests. We need to regenerate * all the projects before this can be removed. */ #ifndef CONFIG_KERN_PRI_INHERIT #define CONFIG_KERN_PRI_INHERIT 0 #endif /* * WARNING: struct Process is considered private, so its definition can change any time * without notice. DO NOT RELY on any field defined here, use only the interface * functions below. * * You have been warned. */ typedef struct Process { #if CONFIG_KERN_PRI PriNode link; /**< Link Process into scheduler lists */ # if CONFIG_KERN_PRI_INHERIT PriNode inh_link; /**< Link Process into priority inheritance lists */ List inh_list; /**< Priority inheritance list for this Process */ Semaphore *inh_blocked_by; /**< Semaphore blocking this Process */ int orig_pri; /**< Process priority without considering inheritance */ # endif #else Node link; /**< Link Process into scheduler lists */ #endif cpu_stack_t *stack; /**< Per-process SP */ iptr_t user_data; /**< Custom data passed to the process */ #if CONFIG_KERN_SIGNALS Signal sig; #endif #if CONFIG_KERN_HEAP uint16_t flags; /**< Flags */ #endif #if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR cpu_stack_t *stack_base; /**< Base of process stack */ size_t stack_size; /**< Size of process stack */ #endif /* The actual process entry point */ void (*user_entry)(void); #if CONFIG_KERN_MONITOR struct ProcMonitor { Node link; const char *name; } monitor; #endif } Process; /** * Initialize the process subsystem (kernel). * It must be called before using any process related function. */ void proc_init(void); struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack); #if !CONFIG_KERN_MONITOR /** * Create a new named process and schedules it for execution. * * When defining the stacksize take into account that you may want at least: * \li save all the registers for each nested function call; * \li have memory for the struct Process, which is positioned at the bottom * of the stack; * \li have some memory for temporary variables inside called functions. * * The value given by KERN_MINSTACKSIZE is rather safe to use in the first place. * * \param entry Function that the process will execute. * \param data Pointer to user data. * \param size Length of the stack. * \param stack Pointer to the memory area to be used as a stack. * * \return Process structure of new created process * if successful, NULL otherwise. */ #define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack)) #else #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack)) #endif /** * Terminate the execution of the current process. */ void proc_exit(void); /* * Public scheduling class methods. */ void proc_yield(void); #if CONFIG_KERN_PREEMPT bool proc_needPreempt(void); void proc_preempt(void); #else INLINE bool proc_needPreempt(void) { return false; } INLINE void proc_preempt(void) { } #endif void proc_rename(struct Process *proc, const char *name); const char *proc_name(struct Process *proc); const char *proc_currentName(void); /** * Return a pointer to the user data of the current process. * * To obtain user data, just call this function inside the process. Remember to cast * the returned pointer to the correct type. * \return Pointer to the user data of the current process. */ INLINE iptr_t proc_currentUserData(void) { extern struct Process *current_process; return current_process->user_data; } int proc_testSetup(void); int proc_testRun(void); int proc_testTearDown(void); /** * Return the context structure of the currently running process. * * The details of the Process structure are private to the scheduler. * The address returned by this function is an opaque pointer that can * be passed as an argument to other process-related functions. */ INLINE struct Process *proc_current(void) { extern struct Process *current_process; return current_process; } #if CONFIG_KERN_PRI void proc_setPri(struct Process *proc, int pri); #else INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri)) { } #endif #if CONFIG_KERN_PREEMPT /** * Disable preemptive task switching. * * The scheduler maintains a global nesting counter. Task switching is * effectively re-enabled only when the number of calls to proc_permit() * matches the number of calls to proc_forbid(). * * \note Calling functions that could sleep while task switching is disabled * is dangerous and unsupported. * * \note proc_permit() expands inline to 1-2 asm instructions, so it's a * very efficient locking primitive in simple but performance-critical * situations. In all other cases, semaphores offer a more flexible and * fine-grained locking primitive. * * \sa proc_permit() */ INLINE void proc_forbid(void) { extern cpu_atomic_t preempt_count; /* * We don't need to protect the counter against other processes. * The reason why is a bit subtle. * * If a process gets here, preempt_forbid_cnt can be either 0, * or != 0. In the latter case, preemption is already disabled * and no concurrency issues can occur. * * In the former case, we could be preempted just after reading the * value 0 from memory, and a concurrent process might, in fact, * bump the value of preempt_forbid_cnt under our nose! * * BUT: if this ever happens, then we won't get another chance to * run until the other process calls proc_permit() to re-enable * preemption. At this point, the value of preempt_forbid_cnt * must be back to 0, and thus what we had originally read from * memory happens to be valid. * * No matter how hard you think about it, and how complicated you * make your scenario, the above holds true as long as * "preempt_forbid_cnt != 0" means that no task switching is * possible. */ ++preempt_count; /* * Make sure preempt_count is flushed to memory so the preemption * softirq will see the correct value from now on. */ MEMORY_BARRIER; } /** * Re-enable preemptive task switching. * * \sa proc_forbid() */ INLINE void proc_permit(void) { extern cpu_atomic_t preempt_count; /* * This is to ensure any global state changed by the process gets * flushed to memory before task switching is re-enabled. */ MEMORY_BARRIER; /* No need to protect against interrupts here. */ ASSERT(preempt_count > 0); --preempt_count; /* * This ensures preempt_count is flushed to memory immediately so the * preemption interrupt sees the correct value. */ MEMORY_BARRIER; } /** * \return true if preemptive task switching is allowed. * \note This accessor is needed because preempt_count * must be absoultely private. */ INLINE bool proc_preemptAllowed(void) { extern cpu_atomic_t preempt_count; return (preempt_count == 0); } #else /* CONFIG_KERN_PREEMPT */ #define proc_forbid() /* NOP */ #define proc_permit() /* NOP */ #define proc_preemptAllowed() (true) #endif /* CONFIG_KERN_PREEMPT */ /** Deprecated, use the proc_preemptAllowed() macro. */ #define proc_allowed() proc_preemptAllowed() /** * Execute a block of \a CODE atomically with respect to task scheduling. */ #define PROC_ATOMIC(CODE) \ do { \ proc_forbid(); \ CODE; \ proc_permit(); \ } while(0) /** * Default stack size for each thread, in bytes. * * The goal here is to allow a minimal task to save all of its * registers twice, plus push a maximum of 32 variables on the * stack. We add also struct Process size since we save it into the process' * stack. * * The actual size computed by the default formula greatly depends on what * options are active and on the architecture. * * Note that on most 16bit architectures, interrupts will also * run on the stack of the currently running process. Nested * interrupts will greatly increases the amount of stack space * required per process. Use irqmanager to minimize stack * usage. */ #if (ARCH & ARCH_EMUL) /* We need a large stack because system libraries are bloated */ #define KERN_MINSTACKSIZE 65536 #else #if CONFIG_KERN_PREEMPT /* * A preemptible kernel needs a larger stack compared to the * cooperative case. A task can be interrupted anytime in each * node of the call graph, at any level of depth. This may * result in a higher stack consumption, to call the ISR, save * the current user context and to execute the kernel * preemption routines implemented as ISR prologue and * epilogue. All these calls are nested into the process stack. * * So, to reduce the risk of stack overflow/underflow problems * add a x2 to the portion stack reserved to the user process. */ #define KERN_MINSTACKSIZE \ (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \ + 32 * sizeof(int) * 2) #else #define KERN_MINSTACKSIZE \ (sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \ + 32 * sizeof(int)) #endif /* CONFIG_KERN_PREEMPT */ #endif #ifndef CONFIG_KERN_MINSTACKSIZE /* For backward compatibility */ #define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE #else #warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead #endif /** * Utility macro to allocate a stack of size \a size. * * This macro define a static stack for one process and do * check if given stack size is enough to run process. * \note If you plan to use kprintf() and similar functions, you will need * at least KERN_MINSTACKSIZE * 2 bytes. * * \param name Variable name for the stack. * \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE. */ #define PROC_DEFINE_STACK(name, size) \ cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \ STATIC_ASSERT((size) >= KERN_MINSTACKSIZE); /* Memory fill codes to help debugging */ #if CONFIG_KERN_MONITOR #include #if (SIZEOF_CPUSTACK_T == 1) /* 8bit cpu_stack_t */ #define CONFIG_KERN_STACKFILLCODE 0xA5 #define CONFIG_KERN_MEMFILLCODE 0xDB #elif (SIZEOF_CPUSTACK_T == 2) /* 16bit cpu_stack_t */ #define CONFIG_KERN_STACKFILLCODE 0xA5A5 #define CONFIG_KERN_MEMFILLCODE 0xDBDB #elif (SIZEOF_CPUSTACK_T == 4) /* 32bit cpu_stack_t */ #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL #elif (SIZEOF_CPUSTACK_T == 8) /* 64bit cpu_stack_t */ #define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL #define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL #else #error No cpu_stack_t size supported! #endif #endif /** \} */ //defgroup kern_proc #endif /* KERN_PROC_H */