390 lines
12 KiB
C
390 lines
12 KiB
C
/* Copyright (C) 2004,2005 David Decotigny
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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USA.
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*/
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#ifndef _SOS_THREAD_H_
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#define _SOS_THREAD_H_
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/**
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* @file thread.h
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*
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* SOS Thread management API
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*/
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#include <sos/errno.h>
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/* Forward declaration */
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struct sos_thread;
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#include <hwcore/cpu_context.h>
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#include <sos/sched.h>
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#include <sos/kwaitq.h>
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#include <sos/time.h>
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#include <sos/process.h>
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/**
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* The possible states of a valid thread
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*/
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typedef enum { SOS_THR_CREATED, /**< Thread created, not fully initialized */
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SOS_THR_READY, /**< Thread fully initialized or
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waiting for CPU after having been
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blocked or preempted */
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SOS_THR_RUNNING, /**< Thread currently running on CPU */
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SOS_THR_BLOCKED, /**< Thread waiting for I/O (+ in at LEAST
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one kwaitq) and/or sleeping (+ in NO
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kwaitq) */
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SOS_THR_ZOMBIE, /**< Thread terminated execution, waiting to
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be deleted by kernel */
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} sos_thread_state_t;
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/**
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* TCB (Thread Control Block): structure describing a thread. Don't
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* access these fields directly: prefer using the accessor functions
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* below.
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*/
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struct sos_thread
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{
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#define SOS_THR_MAX_NAMELEN 32
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char name[SOS_THR_MAX_NAMELEN];
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sos_thread_state_t state;
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sos_sched_priority_t priority;
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/**
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* The hardware context of the thread.
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*
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* It will reflect the CPU state of the thread:
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* - From an interrupt handler: the state of the thread at the time
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* of the OUTERMOST irq. An IRQ is not allowed to make context
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* switches, so this context will remain valid from the begining of
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* the outermost IRQ handler to the end of it, no matter if there
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* are other IRQ handlers nesting in one another. You may safely
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* use it from IRQ handlers to query the state of the interrupted
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* thread, no matter if there has been other IRQ handlers
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* executing meanwhile.
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* - From normal kernel code, exceptions and syscall: the state of
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* the thread the last time there was a context switch from this
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* thread to another one. Thus this field WON'T reflect the
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* current's thread cpu_state in these cases. So, in these cases,
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* simply DO NOT USE IT outside thread.c ! Note: for syscall and
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* exception handlers, the VALID state of the interrupted thread is
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* passed as an argument to the handlers.
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*/
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struct sos_cpu_state *cpu_state;
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/* Kernel stack parameters */
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sos_vaddr_t kernel_stack_base_addr;
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sos_size_t kernel_stack_size;
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/* Process this thread belongs to. Always NULL for a kernel
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thread */
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struct sos_process *process;
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/**
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* Address space currently "squatted" by the thread, or used to be
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* active when the thread was interrupted/preempted. This is the MMU
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* configuration expected before the cpu_state of the thread is
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* restored on CPU.
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* - For kernel threads: should normally be NULL, meaning that the
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* thread will squat the current mm_context currently set in the
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* MMU. Might be NON NULL when a kernel thread squats a given
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* process to manipulate its address space.
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* - For user threads: should normally be NULL. More precisely:
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* - in user mode: the thread->process.mm_context is ALWAYS
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* set on MMU. squatted_mm_context is ALWAYS NULL in this
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* situation, meaning that the thread in user mode uses its
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* process-space as expected
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* - in kernel mode: NULL means that we keep on using the
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* mm_context currently set on MMU, which might be the
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* mm_context of another process. This is natural since a
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* thread in kernel mode normally only uses data in kernel
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* space. BTW, this limits the number of TLB flushes. However,
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* there are exceptions where this squatted_mm_context will
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* NOT be NULL. One is the copy_from/to_user API, which can
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* force the effective mm_context so that the MMU will be
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* (re)configured upon every context to the thread to match
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* the squatted_mm_context. Another exception is when a parent
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* thread creates the address space of a child process, in
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* which case the parent thread might temporarilly decide to
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* switch to the child's process space.
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*
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* This is the SOS implementation of the Linux "Lazy TLB" and
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* address-space loaning.
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*/
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struct sos_mm_context *squatted_mm_context;
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/* Data specific to each state */
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union
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{
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struct
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{
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struct sos_sched_queue *rdy_queue;
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struct sos_thread *rdy_prev, *rdy_next;
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} ready;
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struct
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{
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struct sos_time user_time_spent_in_slice;
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} running;
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}; /* Anonymous union (gcc extenion) */
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/*
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* Data used by the kwaitq subsystem: list of kwaitqueues the thread
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* is waiting for.
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*
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* @note: a RUNNING or READY thread might be in one or more
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* waitqueues ! The only property we have is that, among these
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* waitqueues (if any), _at least_ one has woken the thread.
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*/
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struct sos_kwaitq_entry *kwaitq_list;
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/**
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* Some statistics
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*/
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struct rusage
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{
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/* Updated by sched.c */
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struct sos_time ru_utime; /* Time spent in user mode */
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struct sos_time ru_stime; /* Time spent in kernel mode */
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} rusage;
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/**
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* Chaining pointers for the list of threads in the parent process
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*/
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struct sos_thread *prev_in_process, *next_in_process;
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/**
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* Chaining pointers for global ("gbl") list of threads (debug)
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*/
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struct sos_thread *gbl_prev, *gbl_next;
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};
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/**
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* Definition of the function executed by a kernel thread
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*/
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typedef void (*sos_kernel_thread_start_routine_t)(void *arg);
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/**
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* Initialize the subsystem responsible for thread management
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*
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* Initialize the primary kernel thread so that it can be handled the
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* same way as an ordinary thread created by sos_thread_create().
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*/
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sos_ret_t sos_thread_subsystem_setup(sos_vaddr_t init_thread_stack_base_addr,
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sos_size_t init_thread_stack_size);
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/**
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* Create a new kernel thread
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*/
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struct sos_thread *
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sos_create_kernel_thread(const char *name,
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sos_kernel_thread_start_routine_t start_func,
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void *start_arg,
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sos_sched_priority_t priority);
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/**
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* Create a new user thread
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*/
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struct sos_thread *
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sos_create_user_thread(const char *name,
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struct sos_process *process,
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sos_uaddr_t user_initial_PC,
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sos_ui32_t user_start_arg1,
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sos_ui32_t user_start_arg2,
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sos_uaddr_t user_initial_SP,
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sos_sched_priority_t priority);
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/**
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* Terminate the execution of the current thread. For kernel threads,
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* it is called by default when the start routine returns.
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*/
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void sos_thread_exit() __attribute__((noreturn));
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/**
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* Get the identifier of the thread currently running on CPU. Trivial
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* function.
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*/
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struct sos_thread *sos_thread_get_current();
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/**
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* If thr == NULL, set the priority of the current thread. Trivial
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* function.
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*
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* @note NOT protected against interrupts
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*/
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sos_sched_priority_t sos_thread_get_priority(struct sos_thread *thr);
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/**
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* If thr == NULL, get the state of the current thread. Trivial
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* function.
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*
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* @note NOT protected against interrupts
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*/
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sos_thread_state_t sos_thread_get_state(struct sos_thread *thr);
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/**
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* If thr == NULL, set the priority of the current thread
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*
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* @note NO context-switch ever occurs in this function !
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*/
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sos_ret_t sos_thread_set_priority(struct sos_thread *thr,
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sos_sched_priority_t priority);
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/**
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* Yield CPU to another ready thread.
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*
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* @note This is a BLOCKING FUNCTION
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*/
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sos_ret_t sos_thread_yield();
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/**
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* Release the CPU for (at least) the given delay.
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*
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* @param delay The delay to wait for. If delay == NULL then wait
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* forever that any event occurs.
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*
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* @return SOS_OK when delay expired (and delay is reset to zero),
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* -SOS_EINTR otherwise (and delay contains the amount of time
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* remaining).
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*
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* @note This is a BLOCKING FUNCTION
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*/
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sos_ret_t sos_thread_sleep(/* in/out */struct sos_time *delay);
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/**
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* Mark the given thread as READY (if not already ready) even if it is
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* blocked in a kwaitq or in a sleep ! As a result, the interrupted
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* kwaitq/sleep function call of the thread will return with
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* -SOS_EINTR.
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*
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* @return -SOS_EINVAL if thread does not exist, or -SOS_EFATAL if
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* marked ZOMBIE.
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*
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* @note As a result, the semaphore/mutex/conditions/... functions
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* return values SHOULD ALWAYS be checked ! If they are != SOS_OK,
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* then the caller should consider that the resource is not aquired
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* because somebody woke the thread by some way.
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*/
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sos_ret_t sos_thread_force_unblock(struct sos_thread *thread);
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/**
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* Dump the backtrace of the current thread to console and/or bochs
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*/
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void sos_thread_dump_backtrace(sos_bool_t on_console,
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sos_bool_t on_bochs);
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/* **********************************************
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* Restricted functions
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*/
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/**
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* Restricted function to change the current mm_context AND the
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* squatted_mm_context of the current thread in order to access the data
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* in this context
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*
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* @param mm_ctxt The mm_ctxt to restore. Might be NULL, meaning that:
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* - for a Kernel thread: the current MMU configuration is never
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* modified. The address space to use is limited to the kernel
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* space, user space might change due to preemptions to other
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* processes
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* - for a User thread in kernel mode: same as for kernel threads
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* - when a User thread will go back in user context: the MMU will
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* be reconfigured to match the mm_context of the thread's
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* process
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*
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* @note A non NULL parameter is allowed only if the
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* squatted_mm_context is not already set. A NULL parameter is allowed
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* only if the squatted_mm_context was already set.
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*
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* @note The use of this function is RESERVED to the syscall handler
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* and the copy_from/to_user functions
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*/
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sos_ret_t
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sos_thread_change_current_mm_context(struct sos_mm_context *mm_ctxt);
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/**
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* Restricted callback called when a syscall goes back in user mode,
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* to reconfigure the MMU to match that of the current thread's
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* process MMU context.
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*
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* @note The use of this function is RESERVED to the syscall wrapper
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*/
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void sos_thread_prepare_syscall_switch_back(struct sos_cpu_state *cpu_state);
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/**
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* Restricted callback called when an exception handler goes back to
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* the interrupted thread to reconfigure the MMU to match that of the
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* current thread's process MMU context.
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*
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* @note The use of this function is RESERVED to the exception wrappers
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*/
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void sos_thread_prepare_exception_switch_back(struct sos_cpu_state *cpu_state);
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/**
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* Restricted callback called when an IRQ is entered while the CPU was
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* NOT already servicing any other IRQ (ie the outermost IRQ handler
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* is entered). This callback simply updates the "cpu_state" field so
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* that IRQ handlers always know the state of the interrupted thread,
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* even if they are imbricated in other IRQ handlers.
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*
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* @note The use of this function is RESERVED to the irq wrappers
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*/
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void
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sos_thread_prepare_irq_servicing(struct sos_cpu_state *interrupted_state);
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/**
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* Restricted callback called when the outermost IRQ handler returns,
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* to select the thread to return to. This callbacks implements:
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* - preemption of user threads in user mode (time sharing / FIFO)
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* - non-preemption of user threads in kernel mode (interrupted thread
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* is restored on CPU "as is")
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* - non-preemption of kernel threads (same remark)
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* The MMU is reconfigured correctly to match the address space of the
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* selected thread.
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*
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* @return The CPU context of the thread to return to
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*
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* @note The use of this function is RESERVED to the irq wrappers
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*/
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struct sos_cpu_state *
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sos_thread_prepare_irq_switch_back(void);
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#endif /* _SOS_THREAD_H_ */
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