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