source: trunk/kernel/syscalls/sys_fork.c @ 558

Last change on this file since 558 was 506, checked in by viala@…, 6 years ago

[syscalls] add interface in implementation.

Add const where possible, fix protoypes to follow interface.

File size: 6.4 KB
RevLine 
[1]1/*
[409]2 * sys_fork.c - Kernel function implementing the "fork" system call.
[1]3 *
[23]4 * Authors  Alain Greiner  (2016,2017)
[1]5 *
6 * Copyright (c) UPMC Sorbonne Universites
7 *
8 * This file is part of ALMOS-MKH.
9 *
10 * ALMOS-MKH.is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; version 2.0 of the License.
13 *
14 * ALMOS-MKH.is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with ALMOS-MKH.; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
[23]24#include <kernel_config.h>
[457]25#include <hal_kernel_types.h>
[407]26#include <hal_context.h>
27#include <hal_switch.h>
[23]28#include <hal_atomic.h>
[1]29#include <errno.h>
[23]30#include <printk.h>
31#include <core.h>
[1]32#include <cluster.h>
33#include <list.h>
34#include <thread.h>
35#include <scheduler.h>
36#include <kmem.h>
37#include <dqdt.h>
38#include <process.h>
39
[506]40#include <syscalls.h>
41
[23]42//////////////
[479]43int sys_fork( void )
[1]44{
[408]45        process_t       * parent_process_ptr;   // pointer on local parent process descriptor
46    xptr_t            parent_thread_xp;     // extended pointer on parent thread descriptor
47    pid_t             parent_pid;           // parent process identifier
48    thread_t        * parent_thread_ptr;    // local pointer on local parent thread descriptor
[438]49    cxy_t             parent_cxy;           // parent thread cluster
[1]50
[408]51    pid_t             child_pid;            // child process identifier
52    thread_t        * child_thread_ptr;     // local pointer on remote child thread descriptor
[438]53    cxy_t             child_cxy;            // target cluster for forked child process
[408]54 
55    xptr_t            ref_process_xp;       // extended pointer on reference parent process
56    cxy_t             ref_process_cxy;      // cluster of reference parent process
57    process_t       * ref_process_ptr;      // local pointer on reference parent process
[407]58
[408]59        error_t           error;
60   
61
62    // get pointers on local parent process and thread
63        parent_thread_ptr  = CURRENT_THREAD;
64    parent_thread_xp   = XPTR( local_cxy , parent_thread_ptr );
65        parent_process_ptr = parent_thread_ptr->process;
66    parent_pid         = parent_process_ptr->pid;
[438]67    parent_cxy         = local_cxy;
[1]68
[438]69#if DEBUG_SYS_FORK
[416]70uint64_t          tm_start;
71uint64_t          tm_end;
72tm_start = hal_get_cycles();
[438]73if( DEBUG_SYS_FORK < tm_start )
[457]74printk("\n[DBG] %s : thread %x in process %x enter / cycle =  %d\n",
75__FUNCTION__, parent_thread_ptr->trdid, parent_pid, (uint32_t)tm_start );
[416]76#endif
[407]77
[438]78    // get infos on reference parent process
[408]79    ref_process_xp  = parent_process_ptr->ref_xp;
80    ref_process_cxy = GET_CXY( ref_process_xp );
[440]81    ref_process_ptr = GET_PTR( ref_process_xp );
[408]82
83    // check parent process children number from reference
84    xptr_t   children_xp = XPTR( ref_process_cxy , &ref_process_ptr->children_nr );
85    if( hal_remote_atomic_add( children_xp , 1 ) >= CONFIG_PROCESS_MAX_CHILDREN )
[1]86        {
[435]87
[438]88#if DEBUG_SYSCALLS_ERROR
[435]89printk("\n[ERROR] in %s : too much children processes\n", __FUNCTION__);
90#endif
[408]91            hal_remote_atomic_add ( children_xp , -1 );
92        parent_thread_ptr->errno = EAGAIN;
93        return -1;
[1]94        }
95
[408]96    // Select target cluster for child process and main thread.
[438]97    // If placement is not user-defined, it is defined by the DQDT.
98        if( parent_thread_ptr->fork_user )
[1]99        {
[438]100        child_cxy = parent_thread_ptr->fork_cxy;
[408]101        parent_thread_ptr->fork_user = false;
[1]102        }
[408]103        else                                  // DQDT placement
[1]104        {
[438]105                child_cxy = dqdt_get_cluster_for_process();
[1]106        }
107
[440]108#if (DEBUG_SYS_FORK & 1 )
[438]109if( DEBUG_SYS_FORK < tm_start )
[457]110printk("\n[DBG] %s : thread %x in process %x selected cluster %x\n",
111__FUNCTION__, parent_thread_ptr->trdid, parent_pid, child_cxy );
[438]112#endif
113
[408]114    // call process_make_fork in target cluster
[438]115    if( child_cxy == local_cxy )
[1]116    {
[408]117        error = process_make_fork( ref_process_xp,
118                                   parent_thread_xp,
119                                   &child_pid,
120                                   &child_thread_ptr );
[1]121    }
[408]122    else
[1]123    {
[438]124        rpc_process_make_fork_client( child_cxy,
[408]125                                      ref_process_xp,
126                                      parent_thread_xp,
127                                      &child_pid,
128                                      &child_thread_ptr,
129                                      &error );
[1]130    }
[23]131
[1]132    if( error )
133    {
[435]134
[438]135#if DEBUG_SYSCALLS_ERROR
[435]136printk("\n[ERROR] in %s : cannot fork process %x in cluster %x\n",
137__FUNCTION__, parent_pid, local_cxy );
138#endif
[408]139        parent_thread_ptr->errno = EAGAIN;
140        return -1;
[1]141    }
142
[408]143    // set remote child FPU_context from parent_thread register values
144    // only when the parent thread is the FPU owner
145        if( CURRENT_THREAD->core->fpu_owner == parent_thread_ptr )
[407]146        {
[438]147                hal_fpu_context_save( XPTR( child_cxy , child_thread_ptr ) );
[407]148        }
[1]149
[438]150    // set remote child CPU context from parent_thread register values
151    hal_cpu_context_fork( XPTR( child_cxy , child_thread_ptr ) );
[1]152
[438]153    // From this point, both parent and child threads execute the following code,
154    // but they can be distinguished by the (CURRENT_THREAD,local_cxy) values.
[408]155    // - parent unblock child, and return child PID to user application.
156    // - child thread does nothing, and return 0 to user pplication
[438]157    // The child thread will only execute it when it is unblocked by parent thread.
[1]158
[407]159    thread_t * current = CURRENT_THREAD;
[1]160
[438]161    if( (current == parent_thread_ptr) && (local_cxy == parent_cxy) )   // parent thread
[407]162    {
163        // parent_thread unblock child_thread
[438]164        thread_unblock( XPTR( child_cxy , child_thread_ptr ) , THREAD_BLOCKED_GLOBAL );
[1]165
[438]166#if DEBUG_SYS_FORK
[416]167tm_end = hal_get_cycles();
[438]168if( DEBUG_SYS_FORK < tm_end )
[457]169printk("\n[DBG] %s : process %x exit / cost = %d / cycle %d\n",
170__FUNCTION__, parent_pid, (uint32_t)(tm_end - tm_start), (uint32_t)tm_end );
[416]171#endif
[407]172        return child_pid;
173    }
[438]174        else                                                               // child_thread
[407]175    {
176
[438]177#if DEBUG_SYS_FORK
[416]178tm_end = hal_get_cycles();
[438]179if( DEBUG_SYS_FORK < tm_end )
[457]180printk("\n[DBG] %s : process %x exit / cost = %d / cycle %d\n",
181__FUNCTION__, child_pid, (uint32_t)(tm_end - tm_start), (uint32_t)tm_end );
[416]182#endif
[407]183        return 0;
184    }
185
[1]186}  // end sys_fork()
187
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