/* This task handles the interface between file system and kernel as well as * between memory manager and kernel. System services are obtained by sending * sys_task() a message specifying what is needed. To make life easier for * MM and FS, a library is provided with routines whose names are of the * form sys_xxx, e.g. sys_xit sends the SYS_XIT message to sys_task. The * message types and parameters are: * * SYS_FORK informs kernel that a process has forked * SYS_NEWMAP allows MM to set up a process memory map * SYS_EXEC sets program counter and stack pointer after EXEC * SYS_XIT informs kernel that a process has exited * SYS_GETSP caller wants to read out some process' stack pointer * SYS_TIMES caller wants to get accounting times for a process * SYS_ABORT MM or FS cannot go on; abort MINIX * SYS_SIG send a signal to a process * SYS_COPY requests a block of data to be copied between processes * * Message type m1 is used for all except SYS_SIG and SYS_COPY, both of * which need special parameter types. * * m_type PROC1 PROC2 PID MEM_PTR * ------------------------------------------------------ * | SYS_FORK | parent | child | pid | | * |------------+---------+---------+---------+---------| * | SYS_NEWMAP | proc nr | | | map ptr | * |------------+---------+---------+---------+---------| * | SYS_EXEC | proc nr | | new sp | | * |------------+---------+---------+---------+---------| * | SYS_XIT | parent | exitee | | | * |------------+---------+---------+---------+---------| * | SYS_GETSP | proc nr | | | | * |------------+---------+---------+---------+---------| * | SYS_TIMES | proc nr | | buf ptr | | * |------------+---------+---------+---------+---------| * | SYS_ABORT | | | | | * ------------------------------------------------------ * * * m_type m6_i1 m6_i2 m6_i3 m6_f1 * ------------------------------------------------------ * | SYS_SIG | proc_nr | sig | | handler | * ------------------------------------------------------ * * * m_type m5_c1 m5_i1 m5_l1 m5_c2 m5_i2 m5_l2 m5_l3 * -------------------------------------------------------------------------- * | SYS_COPY |src seg|src proc|src vir|dst seg|dst proc|dst vir| byte ct | * -------------------------------------------------------------------------- * * In addition to the main sys_task() entry point, there are three other minor * entry points: * cause_sig: take action to cause a signal to occur, sooner or later * inform: tell MM about pending signals * umap: compute the physical address for a given virtual address */ #include "../h/const.h" #include "../h/type.h" #include "../h/callnr.h" #include "../h/com.h" #include "../h/error.h" #include "../h/signal.h" #include "const.h" #include "type.h" #include "glo.h" #include "proc.h" #define COPY_UNIT 65534L /* max bytes to copy at once */ extern phys_bytes umap(); PRIVATE message m; PRIVATE char sig_stuff[SIG_PUSH_BYTES]; /* used to send signals to processes */ /*===========================================================================* * sys_task * *===========================================================================*/ PUBLIC sys_task() { /* Main entry point of sys_task. Get the message and dispatch on type. */ register int r; while (TRUE) { receive(ANY, &m); switch (m.m_type) { /* which system call */ case SYS_FORK: r = do_fork(&m); break; case SYS_NEWMAP: r = do_newmap(&m); break; case SYS_EXEC: r = do_exec(&m); break; case SYS_XIT: r = do_xit(&m); break; case SYS_GETSP: r = do_getsp(&m); break; case SYS_TIMES: r = do_times(&m); break; case SYS_ABORT: r = do_abort(&m); break; case SYS_SIG: r = do_sig(&m); break; case SYS_COPY: r = do_copy(&m); break; default: r = E_BAD_FCN; } m.m_type = r; /* 'r' reports status of call */ send(m.m_source, &m); /* send reply to caller */ } } /*===========================================================================* * do_fork * *===========================================================================*/ PRIVATE int do_fork(m_ptr) message *m_ptr; /* pointer to request message */ { /* Handle sys_fork(). 'k1' has forked. The child is 'k2'. */ register struct proc *rpc; register char *sptr, *dptr; /* pointers for copying proc struct */ int k1; /* number of parent process */ int k2; /* number of child process */ int pid; /* process id of child */ int bytes; /* counter for copying proc struct */ k1 = m_ptr->PROC1; /* extract parent slot number from msg */ k2 = m_ptr->PROC2; /* extract child slot number */ pid = m_ptr->PID; /* extract child process id */ if (k1 < 0 || k1 >= NR_PROCS || k2 < 0 || k2 >= NR_PROCS)return(E_BAD_PROC); rpc = proc_addr(k2); /* Copy parent 'proc' struct to child. */ sptr = (char *) proc_addr(k1); /* parent pointer */ dptr = (char *) proc_addr(k2); /* child pointer */ bytes = sizeof(struct proc); /* # bytes to copy */ while (bytes--) *dptr++ = *sptr++; /* copy parent struct to child */ rpc->p_flags |= NO_MAP; /* inhibit the process from running */ rpc->p_pid = pid; /* install child's pid */ rpc->p_reg[RET_REG] = 0; /* child sees pid = 0 to know it is child */ rpc->user_time = 0; /* set all the accounting times to 0 */ rpc->sys_time = 0; rpc->child_utime = 0; rpc->child_stime = 0; return(OK); } /*===========================================================================* * do_newmap * *===========================================================================*/ PRIVATE int do_newmap(m_ptr) message *m_ptr; /* pointer to request message */ { /* Handle sys_newmap(). Fetch the memory map from MM. */ register struct proc *rp, *rsrc; phys_bytes src_phys, dst_phys, pn; vir_bytes vmm, vsys, vn; int caller; /* whose space has the new map (usually MM) */ int k; /* process whose map is to be loaded */ int old_flags; /* value of flags before modification */ struct mem_map *map_ptr; /* virtual address of map inside caller (MM) */ /* Extract message parameters and copy new memory map from MM. */ caller = m_ptr->m_source; k = m_ptr->PROC1; map_ptr = (struct mem_map *) m_ptr->MEM_PTR; if (k < -NR_TASKS || k >= NR_PROCS) return(E_BAD_PROC); rp = proc_addr(k); /* ptr to entry of user getting new map */ rsrc = proc_addr(caller); /* ptr to MM's proc entry */ vn = NR_SEGS * sizeof(struct mem_map); pn = vn; vmm = (vir_bytes) map_ptr; /* careful about sign extension */ vsys = (vir_bytes) rp->p_map; /* again, careful about sign extension */ if ( (src_phys = umap(rsrc, D, vmm, vn)) == 0) panic("bad call to sys_newmap (src)", NO_NUM); if ( (dst_phys = umap(proc_addr(SYSTASK), D, vsys, vn)) == 0) panic("bad call to sys_newmap (dst)", NO_NUM); phys_copy(src_phys, dst_phys, pn); #ifdef i8088 /* On 8088, set segment registers. */ rp->p_reg[CS_REG] = rp->p_map[T].mem_phys; /* set cs */ rp->p_reg[DS_REG] = rp->p_map[D].mem_phys; /* set ds */ rp->p_reg[SS_REG] = rp->p_map[D].mem_phys; /* set ss */ rp->p_reg[ES_REG] = rp->p_map[D].mem_phys; /* set es */ #endif old_flags = rp->p_flags; /* save the previous value of the flags */ rp->p_flags &= ~NO_MAP; if (old_flags != 0 && rp->p_flags == 0) ready(rp); return(OK); } /*===========================================================================* * do_exec * *===========================================================================*/ PRIVATE int do_exec(m_ptr) message *m_ptr; /* pointer to request message */ { /* Handle sys_exec(). A process has done a successful EXEC. Patch it up. */ register struct proc *rp; int k; /* which process */ int *sp; /* new sp */ k = m_ptr->PROC1; /* 'k' tells which process did EXEC */ sp = (int *) m_ptr->STACK_PTR; if (k < 0 || k >= NR_PROCS) return(E_BAD_PROC); rp = proc_addr(k); rp->p_sp = sp; /* set the stack pointer */ rp->p_pcpsw.pc = (int (*)()) 0; /* reset pc */ rp->p_alarm = 0; /* reset alarm timer */ rp->p_flags &= ~RECEIVING; /* MM does not reply to EXEC call */ if (rp->p_flags == 0) ready(rp); set_name(k, sp); /* save command string for F1 display */ return(OK); } /*===========================================================================* * do_xit * *===========================================================================*/ PRIVATE int do_xit(m_ptr) message *m_ptr; /* pointer to request message */ { /* Handle sys_xit(). A process has exited. */ register struct proc *rp, *rc; struct proc *np, *xp; int parent; /* number of exiting proc's parent */ int proc_nr; /* number of process doing the exit */ parent = m_ptr->PROC1; /* slot number of parent process */ proc_nr = m_ptr->PROC2; /* slot number of exiting process */ if (parent < 0 || parent >= NR_PROCS || proc_nr < 0 || proc_nr >= NR_PROCS) return(E_BAD_PROC); rp = proc_addr(parent); rc = proc_addr(proc_nr); rp->child_utime += rc->user_time + rc->child_utime; /* accum child times */ rp->child_stime += rc->sys_time + rc->child_stime; unready(rc); rc->p_alarm = 0; /* turn off alarm timer */ set_name(proc_nr, (char *) 0); /* disable command printing for F1 */ /* If the process being terminated happens to be queued trying to send a * message (i.e., the process was killed by a signal, rather than it doing an * EXIT), then it must be removed from the message queues. */ if (rc->p_flags & SENDING) { /* Check all proc slots to see if the exiting process is queued. */ for (rp = &proc[0]; rp < &proc[NR_TASKS + NR_PROCS]; rp++) { if (rp->p_callerq == NIL_PROC) continue; if (rp->p_callerq == rc) { /* Exiting process is on front of this queue. */ rp->p_callerq = rc->p_sendlink; break; } else { /* See if exiting process is in middle of queue. */ np = rp->p_callerq; while ( ( xp = np->p_sendlink) != NIL_PROC) if (xp == rc) { np->p_sendlink = xp->p_sendlink; break; } else { np = xp; } } } } rc->p_flags = P_SLOT_FREE; return(OK); } /*===========================================================================* * do_getsp * *===========================================================================*/ PRIVATE int do_getsp(m_ptr) message *m_ptr; /* pointer to request message */ { /* Handle sys_getsp(). MM wants to know what sp is. */ register struct proc *rp; int k; /* whose stack pointer is wanted? */ k = m_ptr->PROC1; if (k < 0 || k >= NR_PROCS) return(E_BAD_PROC); rp = proc_addr(k); m.STACK_PTR = (char *) rp->p_sp; /* return sp here */ return(OK); } /*===========================================================================* * do_times * *===========================================================================*/ PRIVATE int do_times(m_ptr) message *m_ptr; /* pointer to request message */ { /* Handle sys_times(). Retrieve the accounting information. */ register struct proc *rp; int k; k = m_ptr->PROC1; /* k tells whose times are wanted */ if (k < 0 || k >= NR_PROCS) return(E_BAD_PROC); rp = proc_addr(k); /* Insert the four times needed by the TIMES system call in the message. */ m_ptr->USER_TIME = rp->user_time; m_ptr->SYSTEM_TIME = rp->sys_time; m_ptr->CHILD_UTIME = rp->child_utime; m_ptr->CHILD_STIME = rp->child_stime; return(OK); } /*===========================================================================* * do_abort * *===========================================================================*/ PRIVATE int do_abort(m_ptr) message *m_ptr; /* pointer to request message */ { /* Handle sys_abort. MINIX is unable to continue. Terminate operation. */ panic("", NO_NUM); } /*===========================================================================* * do_sig * *===========================================================================*/ PRIVATE int do_sig(m_ptr) message *m_ptr; /* pointer to request message */ { /* Handle sys_sig(). Signal a process. The stack is known to be big enough. */ register struct proc *rp; phys_bytes src_phys, dst_phys; vir_bytes vir_addr, sig_size, new_sp; int proc_nr; /* process number */ int sig; /* signal number 1-16 */ int (*sig_handler)(); /* pointer to the signal handler */ /* Extract parameters and prepare to build the words that get pushed. */ proc_nr = m_ptr->PR; /* process being signalled */ sig = m_ptr->SIGNUM; /* signal number, 1 to 16 */ sig_handler = m_ptr->FUNC; /* run time system addr for catching sigs */ if (proc_nr < LOW_USER || proc_nr >= NR_PROCS) return(E_BAD_PROC); rp = proc_addr(proc_nr); vir_addr = (vir_bytes) sig_stuff; /* info to be pushed is in 'sig_stuff' */ new_sp = (vir_bytes) rp->p_sp; /* Actually build the block of words to push onto the stack. */ build_sig(sig_stuff, rp, sig); /* build up the info to be pushed */ /* Prepare to do the push, and do it. */ sig_size = SIG_PUSH_BYTES; new_sp -= sig_size; src_phys = umap(proc_addr(SYSTASK), D, vir_addr, sig_size); dst_phys = umap(rp, S, new_sp, sig_size); if (dst_phys == 0) panic("do_sig can't signal; SP bad", NO_NUM); phys_copy(src_phys, dst_phys, (phys_bytes) sig_size); /* push pc, psw */ /* Change process' sp and pc to reflect the interrupt. */ rp->p_sp = (int *) new_sp; rp->p_pcpsw.pc = sig_handler; return(OK); } /*===========================================================================* * do_copy * *===========================================================================*/ PRIVATE int do_copy(m_ptr) message *m_ptr; /* pointer to request message */ { /* Handle sys_copy(). Copy data for MM or FS. */ int src_proc, dst_proc, src_space, dst_space; vir_bytes src_vir, dst_vir; phys_bytes src_phys, dst_phys, bytes; /* Dismember the command message. */ src_proc = m_ptr->SRC_PROC_NR; dst_proc = m_ptr->DST_PROC_NR; src_space = m_ptr->SRC_SPACE; dst_space = m_ptr->DST_SPACE; src_vir = (vir_bytes) m_ptr->SRC_BUFFER; dst_vir = (vir_bytes) m_ptr->DST_BUFFER; bytes = (phys_bytes) m_ptr->COPY_BYTES; /* Compute the source and destination addresses and do the copy. */ if (src_proc == ABS) src_phys = (phys_bytes) m_ptr->SRC_BUFFER; else src_phys = umap(proc_addr(src_proc),src_space,src_vir,(vir_bytes)bytes); if (dst_proc == ABS) dst_phys = (phys_bytes) m_ptr->DST_BUFFER; else dst_phys = umap(proc_addr(dst_proc),dst_space,dst_vir,(vir_bytes)bytes); if (src_phys == 0 || dst_phys == 0) return(EFAULT); phys_copy(src_phys, dst_phys, bytes); return(OK); } /*===========================================================================* * cause_sig * *===========================================================================*/ PUBLIC cause_sig(proc_nr, sig_nr) int proc_nr; /* process to be signalled */ int sig_nr; /* signal to be sent in range 1 - 16 */ { /* A task wants to send a signal to a process. Examples of such tasks are: * TTY wanting to cause SIGINT upon getting a DEL * CLOCK wanting to cause SIGALRM when timer expires * Signals are handled by sending a message to MM. The tasks don't dare do * that directly, for fear of what would happen if MM were busy. Instead they * call cause_sig, which sets bits in p_pending, and then carefully checks to * see if MM is free. If so, a message is sent to it. If not, when it becomes * free, a message is sent. The calling task always gets control back from * cause_sig() immediately. */ register struct proc *rp; rp = proc_addr(proc_nr); if (rp->p_pending == 0) sig_procs++; /* incr if a new proc is now pending */ rp->p_pending |= 1 << (sig_nr - 1); inform(MM_PROC_NR); /* see if MM is free */ } /*===========================================================================* * inform * *===========================================================================*/ PUBLIC inform(proc_nr) int proc_nr; /* MM_PROC_NR or FS_PROC_NR */ { /* When a signal is detected by the kernel (e.g., DEL), or generated by a task * (e.g. clock task for SIGALRM), cause_sig() is called to set a bit in the * p_pending field of the process to signal. Then inform() is called to see * if MM is idle and can be told about it. Whenever MM blocks, a check is * made to see if 'sig_procs' is nonzero; if so, inform() is called. */ register struct proc *rp, *mmp; /* If MM is not waiting for new input, forget it. */ mmp = proc_addr(proc_nr); if ( ((mmp->p_flags & RECEIVING) == 0) || mmp->p_getfrom != ANY) return; /* MM is waiting for new input. Find a process with pending signals. */ for (rp = proc_addr(0); rp < proc_addr(NR_PROCS); rp++) if (rp->p_pending != 0) { m.m_type = KSIG; m.PROC1 = rp - proc - NR_TASKS; m.SIG_MAP = rp->p_pending; sig_procs--; if (mini_send(HARDWARE, proc_nr, &m) != OK) panic("can't inform MM", NO_NUM); rp->p_pending = 0; /* the ball is now in MM's court */ return; } } /*===========================================================================* * umap * *===========================================================================*/ PUBLIC phys_bytes umap(rp, seg, vir_addr, bytes) register struct proc *rp; /* pointer to proc table entry for process */ int seg; /* T, D, or S segment */ vir_bytes vir_addr; /* virtual address in bytes within the seg */ vir_bytes bytes; /* # of bytes to be copied */ { /* Calculate the physical memory address for a given virtual address. */ vir_clicks vc; /* the virtual address in clicks */ phys_bytes seg_base, pa; /* intermediate variables as phys_bytes */ /* If 'seg' is D it could really be S and vice versa. T really means T. * If the virtual address falls in the gap, it causes a problem. On the * 8088 it is probably a legal stack reference, since "stackfaults" are * not detected by the hardware. On 8088s, the gap is called S and * accepted, but on other machines it is called D and rejected. */ if (bytes <= 0) return( (phys_bytes) 0); vc = (vir_addr + bytes - 1) >> CLICK_SHIFT; /* last click of data */ #ifdef i8088 if (seg != T) seg = (vc < rp->p_map[D].mem_vir + rp->p_map[D].mem_len ? D : S); #else if (seg != T) seg = (vc < rp->p_map[S].mem_vir ? D : S); #endif if((vir_addr>>CLICK_SHIFT) >= rp->p_map[seg].mem_vir + rp->p_map[seg].mem_len) return( (phys_bytes) 0 ); seg_base = (phys_bytes) rp->p_map[seg].mem_phys; seg_base = seg_base << CLICK_SHIFT; /* segment orgin in bytes */ pa = (phys_bytes) vir_addr; pa -= rp->p_map[seg].mem_vir << CLICK_SHIFT; return(seg_base + pa); }