1 /* The kernel call implemented in this file: 2 * m_type: SYS_FORK 3 * 4 * The parameters for this kernel call are: 5 * m_lsys_krn_sys_fork.endpt (parent, process that forked) 6 * m_lsys_krn_sys_fork.slot (child's process table slot) 7 * m_lsys_krn_sys_fork.flags (fork flags) 8 * m_krn_lsys_sys_fork.endpt (endpoint of the child) 9 * m_krn_lsys_sys_fork.msgaddr (new memory map for the child) 10 */ 11 12 #include "kernel/system.h" 13 #include "kernel/vm.h" 14 #include <signal.h> 15 #include <string.h> 16 #include <assert.h> 17 18 #include <minix/endpoint.h> 19 #include <minix/u64.h> 20 21 #if USE_FORK 22 23 /*===========================================================================* 24 * do_fork * 25 *===========================================================================*/ 26 int do_fork(struct proc * caller, message * m_ptr) 27 { 28 /* Handle sys_fork(). 29 * m_lsys_krn_sys_fork.endpt has forked. 30 * The child is m_lsys_krn_sys_fork.slot. 31 */ 32 #if defined(__i386__) 33 char *old_fpu_save_area_p; 34 #endif 35 register struct proc *rpc; /* child process pointer */ 36 struct proc *rpp; /* parent process pointer */ 37 int gen; 38 int p_proc; 39 int namelen; 40 41 if(!isokendpt(m_ptr->m_lsys_krn_sys_fork.endpt, &p_proc)) 42 return EINVAL; 43 44 rpp = proc_addr(p_proc); 45 rpc = proc_addr(m_ptr->m_lsys_krn_sys_fork.slot); 46 if (isemptyp(rpp) || ! isemptyp(rpc)) return(EINVAL); 47 48 assert(!(rpp->p_misc_flags & MF_DELIVERMSG)); 49 50 /* needs to be receiving so we know where the message buffer is */ 51 if(!RTS_ISSET(rpp, RTS_RECEIVING)) { 52 printf("kernel: fork not done synchronously?\n"); 53 return EINVAL; 54 } 55 56 /* make sure that the FPU context is saved in parent before copy */ 57 save_fpu(rpp); 58 /* Copy parent 'proc' struct to child. And reinitialize some fields. */ 59 gen = _ENDPOINT_G(rpc->p_endpoint); 60 #if defined(__i386__) 61 old_fpu_save_area_p = rpc->p_seg.fpu_state; 62 #endif 63 *rpc = *rpp; /* copy 'proc' struct */ 64 #if defined(__i386__) 65 rpc->p_seg.fpu_state = old_fpu_save_area_p; 66 if(proc_used_fpu(rpp)) 67 memcpy(rpc->p_seg.fpu_state, rpp->p_seg.fpu_state, FPU_XFP_SIZE); 68 #endif 69 if(++gen >= _ENDPOINT_MAX_GENERATION) /* increase generation */ 70 gen = 1; /* generation number wraparound */ 71 rpc->p_nr = m_ptr->m_lsys_krn_sys_fork.slot; /* this was obliterated by copy */ 72 rpc->p_endpoint = _ENDPOINT(gen, rpc->p_nr); /* new endpoint of slot */ 73 74 rpc->p_reg.retreg = 0; /* child sees pid = 0 to know it is child */ 75 rpc->p_user_time = 0; /* set all the accounting times to 0 */ 76 rpc->p_sys_time = 0; 77 78 rpc->p_misc_flags &= 79 ~(MF_VIRT_TIMER | MF_PROF_TIMER | MF_SC_TRACE | MF_SPROF_SEEN | MF_STEP); 80 rpc->p_virt_left = 0; /* disable, clear the process-virtual timers */ 81 rpc->p_prof_left = 0; 82 83 /* Mark process name as being a forked copy */ 84 namelen = strlen(rpc->p_name); 85 #define FORKSTR "*F" 86 if(namelen+strlen(FORKSTR) < sizeof(rpc->p_name)) 87 strcat(rpc->p_name, FORKSTR); 88 89 /* the child process is not runnable until it's scheduled. */ 90 RTS_SET(rpc, RTS_NO_QUANTUM); 91 reset_proc_accounting(rpc); 92 93 rpc->p_cpu_time_left = 0; 94 rpc->p_cycles = 0; 95 rpc->p_kcall_cycles = 0; 96 rpc->p_kipc_cycles = 0; 97 rpc->p_signal_received = 0; 98 99 /* If the parent is a privileged process, take away the privileges from the 100 * child process and inhibit it from running by setting the NO_PRIV flag. 101 * The caller should explicitly set the new privileges before executing. 102 */ 103 if (priv(rpp)->s_flags & SYS_PROC) { 104 rpc->p_priv = priv_addr(USER_PRIV_ID); 105 rpc->p_rts_flags |= RTS_NO_PRIV; 106 } 107 108 /* Calculate endpoint identifier, so caller knows what it is. */ 109 m_ptr->m_krn_lsys_sys_fork.endpt = rpc->p_endpoint; 110 m_ptr->m_krn_lsys_sys_fork.msgaddr = rpp->p_delivermsg_vir; 111 112 /* Don't schedule process in VM mode until it has a new pagetable. */ 113 if(m_ptr->m_lsys_krn_sys_fork.flags & PFF_VMINHIBIT) { 114 RTS_SET(rpc, RTS_VMINHIBIT); 115 } 116 117 /* 118 * Only one in group should have RTS_SIGNALED, child doesn't inherit tracing. 119 */ 120 RTS_UNSET(rpc, (RTS_SIGNALED | RTS_SIG_PENDING | RTS_P_STOP)); 121 (void) sigemptyset(&rpc->p_pending); 122 123 #if defined(__i386__) 124 rpc->p_seg.p_cr3 = 0; 125 rpc->p_seg.p_cr3_v = NULL; 126 #elif defined(__arm__) 127 rpc->p_seg.p_ttbr = 0; 128 rpc->p_seg.p_ttbr_v = NULL; 129 #endif 130 131 return OK; 132 } 133 134 #endif /* USE_FORK */ 135