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minix/kernel/proc.c
Ben Gras fe35879325 - panic if there's no runnable process 
- more basic sanity check before recursive enter check (data segment)
 - try to jump to boot monitor instantly on recursive panic
2009-10-03 11:30:35 +00:00

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/* This file contains essentially all of the process and message handling.
* Together with "mpx.s" it forms the lowest layer of the MINIX kernel.
* There is one entry point from the outside:
*
* sys_call: a system call, i.e., the kernel is trapped with an INT
*
* As well as several entry points used from the interrupt and task level:
*
* lock_send: send a message to a process
*
* Changes:
* Aug 19, 2005 rewrote scheduling code (Jorrit N. Herder)
* Jul 25, 2005 rewrote system call handling (Jorrit N. Herder)
* May 26, 2005 rewrote message passing functions (Jorrit N. Herder)
* May 24, 2005 new notification system call (Jorrit N. Herder)
* Oct 28, 2004 nonblocking send and receive calls (Jorrit N. Herder)
*
* The code here is critical to make everything work and is important for the
* overall performance of the system. A large fraction of the code deals with
* list manipulation. To make this both easy to understand and fast to execute
* pointer pointers are used throughout the code. Pointer pointers prevent
* exceptions for the head or tail of a linked list.
*
* node_t *queue, *new_node; // assume these as global variables
* node_t **xpp = &queue; // get pointer pointer to head of queue
* while (*xpp != NULL) // find last pointer of the linked list
* xpp = &(*xpp)->next; // get pointer to next pointer
* *xpp = new_node; // now replace the end (the NULL pointer)
* new_node->next = NULL; // and mark the new end of the list
*
* For example, when adding a new node to the end of the list, one normally
* makes an exception for an empty list and looks up the end of the list for
* nonempty lists. As shown above, this is not required with pointer pointers.
*/
#include <minix/com.h>
#include <minix/callnr.h>
#include <minix/endpoint.h>
#include <stddef.h>
#include <signal.h>
#include <minix/portio.h>
#include <minix/u64.h>
#include "debug.h"
#include "kernel.h"
#include "proc.h"
#include "vm.h"
/* Scheduling and message passing functions. The functions are available to
* other parts of the kernel through lock_...(). The lock temporarily disables
* interrupts to prevent race conditions.
*/
FORWARD _PROTOTYPE( int mini_send, (struct proc *caller_ptr, int dst_e,
message *m_ptr, int flags));
FORWARD _PROTOTYPE( int mini_receive, (struct proc *caller_ptr, int src,
message *m_ptr, int flags));
FORWARD _PROTOTYPE( int mini_senda, (struct proc *caller_ptr,
asynmsg_t *table, size_t size));
FORWARD _PROTOTYPE( int deadlock, (int function,
register struct proc *caller, int src_dst));
FORWARD _PROTOTYPE( int try_async, (struct proc *caller_ptr));
FORWARD _PROTOTYPE( int try_one, (struct proc *src_ptr, struct proc *dst_ptr,
int *postponed));
FORWARD _PROTOTYPE( void sched, (struct proc *rp, int *queue, int *front));
FORWARD _PROTOTYPE( void pick_proc, (void));
#define PICK_ANY 1
#define PICK_HIGHERONLY 2
#define BuildNotifyMessage(m_ptr, src, dst_ptr) \
(m_ptr)->m_type = NOTIFY_FROM(src); \
(m_ptr)->NOTIFY_TIMESTAMP = get_uptime(); \
switch (src) { \
case HARDWARE: \
(m_ptr)->NOTIFY_ARG = priv(dst_ptr)->s_int_pending; \
priv(dst_ptr)->s_int_pending = 0; \
break; \
case SYSTEM: \
(m_ptr)->NOTIFY_ARG = priv(dst_ptr)->s_sig_pending; \
priv(dst_ptr)->s_sig_pending = 0; \
break; \
}
/*===========================================================================*
* QueueMess *
*===========================================================================*/
PRIVATE int QueueMess(endpoint_t ep, vir_bytes msg_lin, struct proc *dst)
{
int k;
phys_bytes addr;
NOREC_ENTER(queuemess);
/* Queue a message from the src process (in memory) to the dst
* process (using dst process table entry). Do actual copy to
* kernel here; it's an error if the copy fails into kernel.
*/
vmassert(!(dst->p_misc_flags & MF_DELIVERMSG));
vmassert(dst->p_delivermsg_lin);
vmassert(isokendpt(ep, &k));
#if 0
if(INMEMORY(dst)) {
PHYS_COPY_CATCH(msg_lin, dst->p_delivermsg_lin,
sizeof(message), addr);
if(!addr) {
PHYS_COPY_CATCH(vir2phys(&ep), dst->p_delivermsg_lin,
sizeof(ep), addr);
if(!addr) {
NOREC_RETURN(queuemess, OK);
}
}
}
#endif
PHYS_COPY_CATCH(msg_lin, vir2phys(&dst->p_delivermsg), sizeof(message), addr);
if(addr) {
NOREC_RETURN(queuemess, EFAULT);
}
dst->p_delivermsg.m_source = ep;
dst->p_misc_flags |= MF_DELIVERMSG;
NOREC_RETURN(queuemess, OK);
}
/*===========================================================================*
* schedcheck *
*===========================================================================*/
PUBLIC void schedcheck(void)
{
/* This function is called an instant before proc_ptr is
* to be scheduled again.
*/
NOREC_ENTER(schedch);
vmassert(intr_disabled());
if(next_ptr) {
proc_ptr = next_ptr;
next_ptr = NULL;
}
vmassert(proc_ptr);
vmassert(!proc_ptr->p_rts_flags);
while (proc_ptr->p_misc_flags &
(MF_DELIVERMSG | MF_SC_DEFER | MF_SC_TRACE | MF_SC_ACTIVE)) {
vmassert(!next_ptr);
vmassert(!proc_ptr->p_rts_flags);
if (proc_ptr->p_misc_flags & MF_DELIVERMSG) {
TRACE(VF_SCHEDULING, printf("delivering to %s / %d\n",
proc_ptr->p_name, proc_ptr->p_endpoint););
if(delivermsg(proc_ptr) == VMSUSPEND) {
vmassert(next_ptr);
TRACE(VF_SCHEDULING,
printf("suspending %s / %d\n",
proc_ptr->p_name,
proc_ptr->p_endpoint););
vmassert(proc_ptr->p_rts_flags);
vmassert(next_ptr != proc_ptr);
}
}
else if (proc_ptr->p_misc_flags & MF_SC_DEFER) {
/* Perform the system call that we deferred earlier. */
#if DEBUG_SCHED_CHECK
if (proc_ptr->p_misc_flags & MF_SC_ACTIVE)
minix_panic("MF_SC_ACTIVE and MF_SC_DEFER set",
NO_NUM);
#endif
arch_do_syscall(proc_ptr);
/* If the process is stopped for signal delivery, and
* not blocked sending a message after the system call,
* inform PM.
*/
if ((proc_ptr->p_misc_flags & MF_SIG_DELAY) &&
!RTS_ISSET(proc_ptr, SENDING))
sig_delay_done(proc_ptr);
}
else if (proc_ptr->p_misc_flags & MF_SC_TRACE) {
/* Trigger a system call leave event if this was a
* system call. We must do this after processing the
* other flags above, both for tracing correctness and
* to be able to use 'break'.
*/
if (!(proc_ptr->p_misc_flags & MF_SC_ACTIVE))
break;
proc_ptr->p_misc_flags &=
~(MF_SC_TRACE | MF_SC_ACTIVE);
/* Signal the "leave system call" event.
* Block the process.
*/
cause_sig(proc_nr(proc_ptr), SIGTRAP);
}
else if (proc_ptr->p_misc_flags & MF_SC_ACTIVE) {
/* If MF_SC_ACTIVE was set, remove it now:
* we're leaving the system call.
*/
proc_ptr->p_misc_flags &= ~MF_SC_ACTIVE;
break;
}
/* If proc_ptr is now descheduled,
* continue with another process.
*/
if (next_ptr) {
proc_ptr = next_ptr;
next_ptr = NULL;
}
}
TRACE(VF_SCHEDULING, printf("starting %s / %d\n",
proc_ptr->p_name, proc_ptr->p_endpoint););
#if DEBUG_TRACE
proc_ptr->p_schedules++;
#endif
NOREC_RETURN(schedch, );
}
/*===========================================================================*
* sys_call *
*===========================================================================*/
PUBLIC int sys_call(call_nr, src_dst_e, m_ptr, bit_map)
int call_nr; /* system call number and flags */
int src_dst_e; /* src to receive from or dst to send to */
message *m_ptr; /* pointer to message in the caller's space */
long bit_map; /* notification event set or flags */
{
/* System calls are done by trapping to the kernel with an INT instruction.
* The trap is caught and sys_call() is called to send or receive a message
* (or both). The caller is always given by 'proc_ptr'.
*/
register struct proc *caller_ptr = proc_ptr; /* get pointer to caller */
int mask_entry; /* bit to check in send mask */
int group_size; /* used for deadlock check */
int result; /* the system call's result */
int src_dst_p; /* Process slot number */
size_t msg_size;
/* If this process is subject to system call tracing, handle that first. */
if (caller_ptr->p_misc_flags & (MF_SC_TRACE | MF_SC_DEFER)) {
/* Are we tracing this process, and is it the first sys_call entry? */
if ((caller_ptr->p_misc_flags & (MF_SC_TRACE | MF_SC_DEFER)) ==
MF_SC_TRACE) {
/* We must notify the tracer before processing the actual
* system call. If we don't, the tracer could not obtain the
* input message. Postpone the entire system call.
*/
caller_ptr->p_misc_flags &= ~MF_SC_TRACE;
caller_ptr->p_misc_flags |= MF_SC_DEFER;
/* Signal the "enter system call" event. Block the process. */
cause_sig(proc_nr(caller_ptr), SIGTRAP);
/* Preserve the return register's value. */
return caller_ptr->p_reg.retreg;
}
/* If the MF_SC_DEFER flag is set, the syscall is now being resumed. */
caller_ptr->p_misc_flags &= ~MF_SC_DEFER;
#if DEBUG_SCHED_CHECK
if (caller_ptr->p_misc_flags & MF_SC_ACTIVE)
minix_panic("MF_SC_ACTIVE already set", NO_NUM);
#endif
/* Set a flag to allow reliable tracing of leaving the system call. */
caller_ptr->p_misc_flags |= MF_SC_ACTIVE;
}
#if DEBUG_SCHED_CHECK
if(caller_ptr->p_misc_flags & MF_DELIVERMSG) {
kprintf("sys_call: MF_DELIVERMSG on for %s / %d\n",
caller_ptr->p_name, caller_ptr->p_endpoint);
minix_panic("MF_DELIVERMSG on", NO_NUM);
}
#endif
#if 0
if(src_dst_e != 4 && src_dst_e != 5 &&
caller_ptr->p_endpoint != 4 && caller_ptr->p_endpoint != 5) {
if(call_nr == SEND)
kprintf("(%d SEND to %d) ", caller_ptr->p_endpoint, src_dst_e);
else if(call_nr == RECEIVE)
kprintf("(%d RECEIVE from %d) ", caller_ptr->p_endpoint, src_dst_e);
else if(call_nr == SENDREC)
kprintf("(%d SENDREC to %d) ", caller_ptr->p_endpoint, src_dst_e);
else
kprintf("(%d %d to/from %d) ", caller_ptr->p_endpoint, call_nr, src_dst_e);
}
#endif
#if DEBUG_SCHED_CHECK
if (RTS_ISSET(caller_ptr, SLOT_FREE))
{
kprintf("called by the dead?!?\n");
return EINVAL;
}
#endif
/* Check destination. SENDA is special because its argument is a table and
* not a single destination. RECEIVE is the only call that accepts ANY (in
* addition to a real endpoint). The other calls (SEND, SENDREC,
* and NOTIFY) require an endpoint to corresponds to a process. In addition,
* it is necessary to check whether a process is allowed to send to a given
* destination.
*/
if (call_nr == SENDA)
{
/* No destination argument */
}
else if (src_dst_e == ANY)
{
if (call_nr != RECEIVE)
{
#if 0
kprintf("sys_call: trap %d by %d with bad endpoint %d\n",
call_nr, proc_nr(caller_ptr), src_dst_e);
#endif
return EINVAL;
}
src_dst_p = src_dst_e;
}
else
{
/* Require a valid source and/or destination process. */
if(!isokendpt(src_dst_e, &src_dst_p)) {
#if 0
kprintf("sys_call: trap %d by %d with bad endpoint %d\n",
call_nr, proc_nr(caller_ptr), src_dst_e);
#endif
return EDEADSRCDST;
}
/* If the call is to send to a process, i.e., for SEND, SENDNB,
* SENDREC or NOTIFY, verify that the caller is allowed to send to
* the given destination.
*/
if (call_nr != RECEIVE)
{
if (!may_send_to(caller_ptr, src_dst_p)) {
#if DEBUG_ENABLE_IPC_WARNINGS
kprintf(
"sys_call: ipc mask denied trap %d from %d to %d\n",
call_nr, caller_ptr->p_endpoint, src_dst_e);
#endif
return(ECALLDENIED); /* call denied by ipc mask */
}
}
}
/* Only allow non-negative call_nr values less than 32 */
if (call_nr < 0 || call_nr >= 32)
{
#if DEBUG_ENABLE_IPC_WARNINGS
kprintf("sys_call: trap %d not allowed, caller %d, src_dst %d\n",
call_nr, proc_nr(caller_ptr), src_dst_p);
#endif
return(ETRAPDENIED); /* trap denied by mask or kernel */
}
/* Check if the process has privileges for the requested call. Calls to the
* kernel may only be SENDREC, because tasks always reply and may not block
* if the caller doesn't do receive().
*/
if (!(priv(caller_ptr)->s_trap_mask & (1 << call_nr))) {
#if DEBUG_ENABLE_IPC_WARNINGS
kprintf("sys_call: trap %d not allowed, caller %d, src_dst %d\n",
call_nr, proc_nr(caller_ptr), src_dst_p);
#endif
return(ETRAPDENIED); /* trap denied by mask or kernel */
}
if ((iskerneln(src_dst_p) && call_nr != SENDREC && call_nr != RECEIVE)) {
#if DEBUG_ENABLE_IPC_WARNINGS
kprintf("sys_call: trap %d not allowed, caller %d, src_dst %d\n",
call_nr, proc_nr(caller_ptr), src_dst_e);
#endif
return(ETRAPDENIED); /* trap denied by mask or kernel */
}
/* Get and check the size of the argument in bytes.
* Normally this is just the size of a regular message, but in the
* case of SENDA the argument is a table.
*/
if(call_nr == SENDA) {
msg_size = (size_t) src_dst_e;
/* Limit size to something reasonable. An arbitrary choice is 16
* times the number of process table entries.
*/
if (msg_size > 16*(NR_TASKS + NR_PROCS))
return EDOM;
msg_size *= sizeof(asynmsg_t); /* convert to bytes */
} else {
msg_size = sizeof(*m_ptr);
}
/* Check for a possible deadlock for blocking SEND(REC) and RECEIVE. */
if (call_nr == SEND || call_nr == SENDREC || call_nr == RECEIVE) {
if (group_size = deadlock(call_nr, caller_ptr, src_dst_p)) {
#if 0
kprintf("sys_call: trap %d from %d to %d deadlocked, group size %d\n",
call_nr, proc_nr(caller_ptr), src_dst_p, group_size);
#endif
return(ELOCKED);
}
}
/* Now check if the call is known and try to perform the request. The only
* system calls that exist in MINIX are sending and receiving messages.
* - SENDREC: combines SEND and RECEIVE in a single system call
* - SEND: sender blocks until its message has been delivered
* - RECEIVE: receiver blocks until an acceptable message has arrived
* - NOTIFY: asynchronous call; deliver notification or mark pending
* - SENDA: list of asynchronous send requests
*/
switch(call_nr) {
case SENDREC:
/* A flag is set so that notifications cannot interrupt SENDREC. */
caller_ptr->p_misc_flags |= MF_REPLY_PEND;
/* fall through */
case SEND:
result = mini_send(caller_ptr, src_dst_e, m_ptr, 0);
if (call_nr == SEND || result != OK)
break; /* done, or SEND failed */
/* fall through for SENDREC */
case RECEIVE:
if (call_nr == RECEIVE)
caller_ptr->p_misc_flags &= ~MF_REPLY_PEND;
result = mini_receive(caller_ptr, src_dst_e, m_ptr, 0);
break;
case NOTIFY:
result = mini_notify(caller_ptr, src_dst_e);
break;
case SENDNB:
result = mini_send(caller_ptr, src_dst_e, m_ptr, NON_BLOCKING);
break;
case SENDA:
result = mini_senda(caller_ptr, (asynmsg_t *)m_ptr, (size_t)src_dst_e);
break;
default:
result = EBADCALL; /* illegal system call */
}
/* Now, return the result of the system call to the caller. */
return(result);
}
/*===========================================================================*
* deadlock *
*===========================================================================*/
PRIVATE int deadlock(function, cp, src_dst)
int function; /* trap number */
register struct proc *cp; /* pointer to caller */
int src_dst; /* src or dst process */
{
/* Check for deadlock. This can happen if 'caller_ptr' and 'src_dst' have
* a cyclic dependency of blocking send and receive calls. The only cyclic
* depency that is not fatal is if the caller and target directly SEND(REC)
* and RECEIVE to each other. If a deadlock is found, the group size is
* returned. Otherwise zero is returned.
*/
register struct proc *xp; /* process pointer */
int group_size = 1; /* start with only caller */
int trap_flags;
#if DEBUG_ENABLE_IPC_WARNINGS
static struct proc *processes[NR_PROCS + NR_TASKS];
processes[0] = cp;
#endif
while (src_dst != ANY) { /* check while process nr */
int src_dst_e;
xp = proc_addr(src_dst); /* follow chain of processes */
#if DEBUG_ENABLE_IPC_WARNINGS
processes[group_size] = xp;
#endif
group_size ++; /* extra process in group */
/* Check whether the last process in the chain has a dependency. If it
* has not, the cycle cannot be closed and we are done.
*/
if (RTS_ISSET(xp, RECEIVING)) { /* xp has dependency */
if(xp->p_getfrom_e == ANY) src_dst = ANY;
else okendpt(xp->p_getfrom_e, &src_dst);
} else if (RTS_ISSET(xp, SENDING)) { /* xp has dependency */
okendpt(xp->p_sendto_e, &src_dst);
} else {
return(0); /* not a deadlock */
}
/* Now check if there is a cyclic dependency. For group sizes of two,
* a combination of SEND(REC) and RECEIVE is not fatal. Larger groups
* or other combinations indicate a deadlock.
*/
if (src_dst == proc_nr(cp)) { /* possible deadlock */
if (group_size == 2) { /* caller and src_dst */
/* The function number is magically converted to flags. */
if ((xp->p_rts_flags ^ (function << 2)) & SENDING) {
return(0); /* not a deadlock */
}
}
#if DEBUG_ENABLE_IPC_WARNINGS
{
int i;
kprintf("deadlock between these processes:\n");
for(i = 0; i < group_size; i++) {
kprintf(" %10s ", processes[i]->p_name);
proc_stacktrace(processes[i]);
}
}
#endif
return(group_size); /* deadlock found */
}
}
return(0); /* not a deadlock */
}
/*===========================================================================*
* mini_send *
*===========================================================================*/
PRIVATE int mini_send(caller_ptr, dst_e, m_ptr, flags)
register struct proc *caller_ptr; /* who is trying to send a message? */
int dst_e; /* to whom is message being sent? */
message *m_ptr; /* pointer to message buffer */
int flags;
{
/* Send a message from 'caller_ptr' to 'dst'. If 'dst' is blocked waiting
* for this message, copy the message to it and unblock 'dst'. If 'dst' is
* not waiting at all, or is waiting for another source, queue 'caller_ptr'.
*/
register struct proc *dst_ptr;
register struct proc **xpp;
int dst_p;
phys_bytes linaddr;
vir_bytes addr;
int r;
if(!(linaddr = umap_local(caller_ptr, D, (vir_bytes) m_ptr,
sizeof(message)))) {
return EFAULT;
}
dst_p = _ENDPOINT_P(dst_e);
dst_ptr = proc_addr(dst_p);
if (RTS_ISSET(dst_ptr, NO_ENDPOINT))
{
return EDSTDIED;
}
/* Check if 'dst' is blocked waiting for this message. The destination's
* SENDING flag may be set when its SENDREC call blocked while sending.
*/
if (WILLRECEIVE(dst_ptr, caller_ptr->p_endpoint)) {
/* Destination is indeed waiting for this message. */
vmassert(!(dst_ptr->p_misc_flags & MF_DELIVERMSG));
if((r=QueueMess(caller_ptr->p_endpoint, linaddr, dst_ptr)) != OK)
return r;
RTS_UNSET(dst_ptr, RECEIVING);
} else {
if(flags & NON_BLOCKING) {
return(ENOTREADY);
}
/* Destination is not waiting. Block and dequeue caller. */
PHYS_COPY_CATCH(linaddr, vir2phys(&caller_ptr->p_sendmsg),
sizeof(message), addr);
if(addr) { return EFAULT; }
RTS_SET(caller_ptr, SENDING);
caller_ptr->p_sendto_e = dst_e;
/* Process is now blocked. Put in on the destination's queue. */
xpp = &dst_ptr->p_caller_q; /* find end of list */
while (*xpp != NIL_PROC) xpp = &(*xpp)->p_q_link;
*xpp = caller_ptr; /* add caller to end */
caller_ptr->p_q_link = NIL_PROC; /* mark new end of list */
}
return(OK);
}
/*===========================================================================*
* mini_receive *
*===========================================================================*/
PRIVATE int mini_receive(caller_ptr, src_e, m_ptr, flags)
register struct proc *caller_ptr; /* process trying to get message */
int src_e; /* which message source is wanted */
message *m_ptr; /* pointer to message buffer */
int flags;
{
/* A process or task wants to get a message. If a message is already queued,
* acquire it and deblock the sender. If no message from the desired source
* is available block the caller.
*/
register struct proc **xpp;
register struct notification **ntf_q_pp;
message m;
int bit_nr;
sys_map_t *map;
bitchunk_t *chunk;
int i, r, src_id, src_proc_nr, src_p;
phys_bytes linaddr;
vmassert(!(caller_ptr->p_misc_flags & MF_DELIVERMSG));
if(!(linaddr = umap_local(caller_ptr, D, (vir_bytes) m_ptr,
sizeof(message)))) {
return EFAULT;
}
/* This is where we want our message. */
caller_ptr->p_delivermsg_lin = linaddr;
caller_ptr->p_delivermsg_vir = (vir_bytes) m_ptr;
if(src_e == ANY) src_p = ANY;
else
{
okendpt(src_e, &src_p);
if (RTS_ISSET(proc_addr(src_p), NO_ENDPOINT))
{
return ESRCDIED;
}
}
/* Check to see if a message from desired source is already available.
* The caller's SENDING flag may be set if SENDREC couldn't send. If it is
* set, the process should be blocked.
*/
if (!RTS_ISSET(caller_ptr, SENDING)) {
/* Check if there are pending notifications, except for SENDREC. */
if (! (caller_ptr->p_misc_flags & MF_REPLY_PEND)) {
map = &priv(caller_ptr)->s_notify_pending;
for (chunk=&map->chunk[0]; chunk<&map->chunk[NR_SYS_CHUNKS]; chunk++) {
endpoint_t hisep;
/* Find a pending notification from the requested source. */
if (! *chunk) continue; /* no bits in chunk */
for (i=0; ! (*chunk & (1<<i)); ++i) {} /* look up the bit */
src_id = (chunk - &map->chunk[0]) * BITCHUNK_BITS + i;
if (src_id >= NR_SYS_PROCS) break; /* out of range */
src_proc_nr = id_to_nr(src_id); /* get source proc */
#if DEBUG_ENABLE_IPC_WARNINGS
if(src_proc_nr == NONE) {
kprintf("mini_receive: sending notify from NONE\n");
}
#endif
if (src_e!=ANY && src_p != src_proc_nr) continue;/* source not ok */
*chunk &= ~(1 << i); /* no longer pending */
/* Found a suitable source, deliver the notification message. */
BuildNotifyMessage(&m, src_proc_nr, caller_ptr); /* assemble message */
hisep = proc_addr(src_proc_nr)->p_endpoint;
vmassert(!(caller_ptr->p_misc_flags & MF_DELIVERMSG));
vmassert(src_e == ANY || hisep == src_e);
if((r=QueueMess(hisep, vir2phys(&m), caller_ptr)) != OK) {
minix_panic("mini_receive: local QueueMess failed", NO_NUM);
}
return(OK); /* report success */
}
}
/* Check caller queue. Use pointer pointers to keep code simple. */
xpp = &caller_ptr->p_caller_q;
while (*xpp != NIL_PROC) {
if (src_e == ANY || src_p == proc_nr(*xpp)) {
#if DEBUG_SCHED_CHECK
if (RTS_ISSET(*xpp, SLOT_FREE) || RTS_ISSET(*xpp, NO_ENDPOINT))
{
kprintf("%d: receive from %d; found dead %d (%s)?\n",
caller_ptr->p_endpoint, src_e, (*xpp)->p_endpoint,
(*xpp)->p_name);
return EINVAL;
}
#endif
/* Found acceptable message. Copy it and update status. */
vmassert(!(caller_ptr->p_misc_flags & MF_DELIVERMSG));
QueueMess((*xpp)->p_endpoint,
vir2phys(&(*xpp)->p_sendmsg), caller_ptr);
if ((*xpp)->p_misc_flags & MF_SIG_DELAY)
sig_delay_done(*xpp);
RTS_UNSET(*xpp, SENDING);
*xpp = (*xpp)->p_q_link; /* remove from queue */
return(OK); /* report success */
}
xpp = &(*xpp)->p_q_link; /* proceed to next */
}
if (caller_ptr->p_misc_flags & MF_ASYNMSG)
{
if (src_e != ANY)
r= try_one(proc_addr(src_p), caller_ptr, NULL);
else
r= try_async(caller_ptr);
if (r == OK)
return OK; /* Got a message */
}
}
/* No suitable message is available or the caller couldn't send in SENDREC.
* Block the process trying to receive, unless the flags tell otherwise.
*/
if ( ! (flags & NON_BLOCKING)) {
caller_ptr->p_getfrom_e = src_e;
RTS_SET(caller_ptr, RECEIVING);
return(OK);
} else {
return(ENOTREADY);
}
}
/*===========================================================================*
* mini_notify *
*===========================================================================*/
PUBLIC int mini_notify(caller_ptr, dst_e)
register struct proc *caller_ptr; /* sender of the notification */
endpoint_t dst_e; /* which process to notify */
{
register struct proc *dst_ptr;
int src_id; /* source id for late delivery */
message m; /* the notification message */
int r;
int proc_nr;
int dst_p;
vmassert(intr_disabled());
if (!isokendpt(dst_e, &dst_p)) {
util_stacktrace();
kprintf("mini_notify: bogus endpoint %d\n", dst_e);
return EDEADSRCDST;
}
dst_ptr = proc_addr(dst_p);
/* Check to see if target is blocked waiting for this message. A process
* can be both sending and receiving during a SENDREC system call.
*/
if (WILLRECEIVE(dst_ptr, caller_ptr->p_endpoint) &&
! (dst_ptr->p_misc_flags & MF_REPLY_PEND)) {
/* Destination is indeed waiting for a message. Assemble a notification
* message and deliver it. Copy from pseudo-source HARDWARE, since the
* message is in the kernel's address space.
*/
BuildNotifyMessage(&m, proc_nr(caller_ptr), dst_ptr);
vmassert(!(dst_ptr->p_misc_flags & MF_DELIVERMSG));
if((r=QueueMess(caller_ptr->p_endpoint, vir2phys(&m), dst_ptr)) != OK) {
minix_panic("mini_notify: local QueueMess failed", NO_NUM);
}
RTS_UNSET(dst_ptr, RECEIVING);
return(OK);
}
/* Destination is not ready to receive the notification. Add it to the
* bit map with pending notifications. Note the indirectness: the system id
* instead of the process number is used in the pending bit map.
*/
src_id = priv(caller_ptr)->s_id;
set_sys_bit(priv(dst_ptr)->s_notify_pending, src_id);
return(OK);
}
#define ASCOMPLAIN(caller, entry, field) \
kprintf("kernel:%s:%d: asyn failed for %s in %s " \
"(%d/%d, tab 0x%lx)\n",__FILE__,__LINE__, \
field, caller->p_name, entry, priv(caller)->s_asynsize, priv(caller)->s_asyntab)
#define A_RETRIEVE(entry, field) \
if(data_copy(caller_ptr->p_endpoint, \
table_v + (entry)*sizeof(asynmsg_t) + offsetof(struct asynmsg,field),\
SYSTEM, (vir_bytes) &tabent.field, \
sizeof(tabent.field)) != OK) {\
ASCOMPLAIN(caller_ptr, entry, #field); \
return EFAULT; \
}
#define A_INSERT(entry, field) \
if(data_copy(SYSTEM, (vir_bytes) &tabent.field, \
caller_ptr->p_endpoint, \
table_v + (entry)*sizeof(asynmsg_t) + offsetof(struct asynmsg,field),\
sizeof(tabent.field)) != OK) {\
ASCOMPLAIN(caller_ptr, entry, #field); \
return EFAULT; \
}
/*===========================================================================*
* mini_senda *
*===========================================================================*/
PRIVATE int mini_senda(caller_ptr, table, size)
struct proc *caller_ptr;
asynmsg_t *table;
size_t size;
{
int i, dst_p, done, do_notify, r;
unsigned flags;
struct proc *dst_ptr;
struct priv *privp;
message *m_ptr;
asynmsg_t tabent;
vir_bytes table_v = (vir_bytes) table;
vir_bytes linaddr;
privp= priv(caller_ptr);
if (!(privp->s_flags & SYS_PROC))
{
kprintf(
"mini_senda: warning caller has no privilege structure\n");
return EPERM;
}
/* Clear table */
privp->s_asyntab= -1;
privp->s_asynsize= 0;
if (size == 0)
{
/* Nothing to do, just return */
return OK;
}
if(!(linaddr = umap_local(caller_ptr, D, (vir_bytes) table,
size * sizeof(*table)))) {
printf("mini_senda: umap_local failed; 0x%lx len 0x%lx\n",
table, size * sizeof(*table));
return EFAULT;
}
/* Limit size to something reasonable. An arbitrary choice is 16
* times the number of process table entries.
*
* (this check has been duplicated in sys_call but is left here
* as a sanity check)
*/
if (size > 16*(NR_TASKS + NR_PROCS))
{
return EDOM;
}
/* Scan the table */
do_notify= FALSE;
done= TRUE;
for (i= 0; i<size; i++)
{
/* Read status word */
A_RETRIEVE(i, flags);
flags= tabent.flags;
/* Skip empty entries */
if (flags == 0)
continue;
/* Check for reserved bits in the flags field */
if (flags & ~(AMF_VALID|AMF_DONE|AMF_NOTIFY|AMF_NOREPLY) ||
!(flags & AMF_VALID))
{
return EINVAL;
}
/* Skip entry if AMF_DONE is already set */
if (flags & AMF_DONE)
continue;
/* Get destination */
A_RETRIEVE(i, dst);
if (!isokendpt(tabent.dst, &dst_p))
{
/* Bad destination, report the error */
tabent.result= EDEADSRCDST;
A_INSERT(i, result);
tabent.flags= flags | AMF_DONE;
A_INSERT(i, flags);
if (flags & AMF_NOTIFY)
do_notify= 1;
continue;
}
if (!may_send_to(caller_ptr, dst_p))
{
/* Send denied by IPC mask */
tabent.result= ECALLDENIED;
A_INSERT(i, result);
tabent.flags= flags | AMF_DONE;
A_INSERT(i, flags);
if (flags & AMF_NOTIFY)
do_notify= 1;
continue;
}
#if 0
kprintf("mini_senda: entry[%d]: flags 0x%x dst %d/%d\n",
i, tabent.flags, tabent.dst, dst_p);
#endif
dst_ptr = proc_addr(dst_p);
/* NO_ENDPOINT should be removed */
if (dst_ptr->p_rts_flags & NO_ENDPOINT)
{
tabent.result= EDSTDIED;
A_INSERT(i, result);
tabent.flags= flags | AMF_DONE;
A_INSERT(i, flags);
if (flags & AMF_NOTIFY)
do_notify= TRUE;
continue;
}
/* Check if 'dst' is blocked waiting for this message.
* If AMF_NOREPLY is set, do not satisfy the receiving part of
* a SENDREC.
*/
if (WILLRECEIVE(dst_ptr, caller_ptr->p_endpoint) &&
(!(flags & AMF_NOREPLY) ||
!(dst_ptr->p_misc_flags & MF_REPLY_PEND)))
{
/* Destination is indeed waiting for this message. */
m_ptr= &table[i].msg; /* Note: pointer in the
* caller's address space.
*/
/* Copy message from sender. */
tabent.result= QueueMess(caller_ptr->p_endpoint,
linaddr + (vir_bytes) &table[i].msg -
(vir_bytes) table, dst_ptr);
if(tabent.result == OK)
RTS_UNSET(dst_ptr, RECEIVING);
A_INSERT(i, result);
tabent.flags= flags | AMF_DONE;
A_INSERT(i, flags);
if (flags & AMF_NOTIFY)
do_notify= 1;
continue;
}
else
{
/* Should inform receiver that something is pending */
dst_ptr->p_misc_flags |= MF_ASYNMSG;
done= FALSE;
continue;
}
}
if (do_notify)
kprintf("mini_senda: should notify caller\n");
if (!done)
{
privp->s_asyntab= (vir_bytes)table;
privp->s_asynsize= size;
}
return OK;
}
/*===========================================================================*
* try_async *
*===========================================================================*/
PRIVATE int try_async(caller_ptr)
struct proc *caller_ptr;
{
int r;
struct priv *privp;
struct proc *src_ptr;
int postponed = FALSE;
/* Try all privilege structures */
for (privp = BEG_PRIV_ADDR; privp < END_PRIV_ADDR; ++privp)
{
if (privp->s_proc_nr == NONE)
continue;
src_ptr= proc_addr(privp->s_proc_nr);
vmassert(!(caller_ptr->p_misc_flags & MF_DELIVERMSG));
r= try_one(src_ptr, caller_ptr, &postponed);
if (r == OK)
return r;
}
/* Nothing found, clear MF_ASYNMSG unless messages were postponed */
if (postponed == FALSE)
caller_ptr->p_misc_flags &= ~MF_ASYNMSG;
return ESRCH;
}
/*===========================================================================*
* try_one *
*===========================================================================*/
PRIVATE int try_one(src_ptr, dst_ptr, postponed)
struct proc *src_ptr;
struct proc *dst_ptr;
int *postponed;
{
int i, do_notify, done;
unsigned flags;
size_t size;
endpoint_t dst_e;
asynmsg_t *table_ptr;
message *m_ptr;
struct priv *privp;
asynmsg_t tabent;
vir_bytes table_v;
struct proc *caller_ptr;
int r;
privp= priv(src_ptr);
/* Basic validity checks */
if (privp->s_id == USER_PRIV_ID) return EAGAIN;
if (privp->s_asynsize == 0) return EAGAIN;
if (!may_send_to(src_ptr, proc_nr(dst_ptr))) return EAGAIN;
size= privp->s_asynsize;
table_v = privp->s_asyntab;
caller_ptr = src_ptr;
dst_e= dst_ptr->p_endpoint;
/* Scan the table */
do_notify= FALSE;
done= TRUE;
for (i= 0; i<size; i++)
{
/* Read status word */
A_RETRIEVE(i, flags);
flags= tabent.flags;
/* Skip empty entries */
if (flags == 0)
{
continue;
}
/* Check for reserved bits in the flags field */
if (flags & ~(AMF_VALID|AMF_DONE|AMF_NOTIFY|AMF_NOREPLY) ||
!(flags & AMF_VALID))
{
kprintf("try_one: bad bits in table\n");
privp->s_asynsize= 0;
return EINVAL;
}
/* Skip entry is AMF_DONE is already set */
if (flags & AMF_DONE)
{
continue;
}
/* Clear done. We are done when all entries are either empty
* or done at the start of the call.
*/
done= FALSE;
/* Get destination */
A_RETRIEVE(i, dst);
if (tabent.dst != dst_e)
{
continue;
}
/* If AMF_NOREPLY is set, do not satisfy the receiving part of
* a SENDREC. Do not unset MF_ASYNMSG later because of this,
* though: this message is still to be delivered later.
*/
if ((flags & AMF_NOREPLY) &&
(dst_ptr->p_misc_flags & MF_REPLY_PEND))
{
if (postponed != NULL)
*postponed = TRUE;
continue;
}
/* Deliver message */
table_ptr= (asynmsg_t *)privp->s_asyntab;
m_ptr= &table_ptr[i].msg; /* Note: pointer in the
* caller's address space.
*/
A_RETRIEVE(i, msg);
r = QueueMess(src_ptr->p_endpoint, vir2phys(&tabent.msg),
dst_ptr);
tabent.result= r;
A_INSERT(i, result);
tabent.flags= flags | AMF_DONE;
A_INSERT(i, flags);
if (flags & AMF_NOTIFY)
{
kprintf("try_one: should notify caller\n");
}
return OK;
}
if (done)
privp->s_asynsize= 0;
return EAGAIN;
}
/*===========================================================================*
* lock_notify *
*===========================================================================*/
PUBLIC int lock_notify(src_e, dst_e)
int src_e; /* (endpoint) sender of the notification */
int dst_e; /* (endpoint) who is to be notified */
{
/* Safe gateway to mini_notify() for tasks and interrupt handlers. The sender
* is explicitely given to prevent confusion where the call comes from. MINIX
* kernel is not reentrant, which means to interrupts are disabled after
* the first kernel entry (hardware interrupt, trap, or exception). Locking
* is done by temporarily disabling interrupts.
*/
int result, src_p;
vmassert(!intr_disabled());
if (!isokendpt(src_e, &src_p)) {
kprintf("lock_notify: bogus src: %d\n", src_e);
return EDEADSRCDST;
}
lock;
vmassert(intr_disabled());
result = mini_notify(proc_addr(src_p), dst_e);
vmassert(intr_disabled());
unlock;
vmassert(!intr_disabled());
return(result);
}
/*===========================================================================*
* enqueue *
*===========================================================================*/
PUBLIC void enqueue(rp)
register struct proc *rp; /* this process is now runnable */
{
/* Add 'rp' to one of the queues of runnable processes. This function is
* responsible for inserting a process into one of the scheduling queues.
* The mechanism is implemented here. The actual scheduling policy is
* defined in sched() and pick_proc().
*/
int q; /* scheduling queue to use */
int front; /* add to front or back */
NOREC_ENTER(enqueuefunc);
#if DEBUG_SCHED_CHECK
if(!intr_disabled()) { minix_panic("enqueue with interrupts enabled", NO_NUM); }
if (rp->p_ready) minix_panic("enqueue already ready process", NO_NUM);
#endif
/* Determine where to insert to process. */
sched(rp, &q, &front);
vmassert(q >= 0);
vmassert(q < IDLE_Q || rp->p_endpoint == IDLE);
/* Now add the process to the queue. */
if (rdy_head[q] == NIL_PROC) { /* add to empty queue */
rdy_head[q] = rdy_tail[q] = rp; /* create a new queue */
rp->p_nextready = NIL_PROC; /* mark new end */
}
else if (front) { /* add to head of queue */
rp->p_nextready = rdy_head[q]; /* chain head of queue */
rdy_head[q] = rp; /* set new queue head */
}
else { /* add to tail of queue */
rdy_tail[q]->p_nextready = rp; /* chain tail of queue */
rdy_tail[q] = rp; /* set new queue tail */
rp->p_nextready = NIL_PROC; /* mark new end */
}
#if DEBUG_SCHED_CHECK
rp->p_ready = 1;
CHECK_RUNQUEUES;
#endif
/* Now select the next process to run, if there isn't a current
* process yet or current process isn't ready any more, or
* it's PREEMPTIBLE.
*/
vmassert(proc_ptr);
if((proc_ptr->p_priority > rp->p_priority) &&
(priv(proc_ptr)->s_flags & PREEMPTIBLE))
pick_proc();
#if DEBUG_SCHED_CHECK
CHECK_RUNQUEUES;
#endif
NOREC_RETURN(enqueuefunc, );
}
/*===========================================================================*
* dequeue *
*===========================================================================*/
PUBLIC void dequeue(rp)
register struct proc *rp; /* this process is no longer runnable */
{
/* A process must be removed from the scheduling queues, for example, because
* it has blocked. If the currently active process is removed, a new process
* is picked to run by calling pick_proc().
*/
register int q = rp->p_priority; /* queue to use */
register struct proc **xpp; /* iterate over queue */
register struct proc *prev_xp;
NOREC_ENTER(dequeuefunc);
#if DEBUG_STACK_CHECK
/* Side-effect for kernel: check if the task's stack still is ok? */
if (iskernelp(rp)) {
if (*priv(rp)->s_stack_guard != STACK_GUARD)
minix_panic("stack overrun by task", proc_nr(rp));
}
#endif
#if DEBUG_SCHED_CHECK
if(!intr_disabled()) { minix_panic("dequeue with interrupts enabled", NO_NUM); }
if (! rp->p_ready) minix_panic("dequeue() already unready process", NO_NUM);
#endif
/* Now make sure that the process is not in its ready queue. Remove the
* process if it is found. A process can be made unready even if it is not
* running by being sent a signal that kills it.
*/
prev_xp = NIL_PROC;
for (xpp = &rdy_head[q]; *xpp != NIL_PROC; xpp = &(*xpp)->p_nextready) {
if (*xpp == rp) { /* found process to remove */
*xpp = (*xpp)->p_nextready; /* replace with next chain */
if (rp == rdy_tail[q]) /* queue tail removed */
rdy_tail[q] = prev_xp; /* set new tail */
#if DEBUG_SCHED_CHECK
rp->p_ready = 0;
CHECK_RUNQUEUES;
#endif
if (rp == proc_ptr || rp == next_ptr) /* active process removed */
pick_proc(); /* pick new process to run */
break;
}
prev_xp = *xpp; /* save previous in chain */
}
#if DEBUG_SCHED_CHECK
CHECK_RUNQUEUES;
#endif
NOREC_RETURN(dequeuefunc, );
}
/*===========================================================================*
* sched *
*===========================================================================*/
PRIVATE void sched(rp, queue, front)
register struct proc *rp; /* process to be scheduled */
int *queue; /* return: queue to use */
int *front; /* return: front or back */
{
/* This function determines the scheduling policy. It is called whenever a
* process must be added to one of the scheduling queues to decide where to
* insert it. As a side-effect the process' priority may be updated.
*/
int time_left = (rp->p_ticks_left > 0); /* quantum fully consumed */
/* Check whether the process has time left. Otherwise give a new quantum
* and lower the process' priority, unless the process already is in the
* lowest queue.
*/
if (! time_left) { /* quantum consumed ? */
rp->p_ticks_left = rp->p_quantum_size; /* give new quantum */
if (rp->p_priority < (IDLE_Q-1)) {
rp->p_priority += 1; /* lower priority */
}
}
/* If there is time left, the process is added to the front of its queue,
* so that it can immediately run. The queue to use simply is always the
* process' current priority.
*/
*queue = rp->p_priority;
*front = time_left;
}
/*===========================================================================*
* pick_proc *
*===========================================================================*/
PRIVATE void pick_proc()
{
/* Decide who to run now. A new process is selected by setting 'next_ptr'.
* When a billable process is selected, record it in 'bill_ptr', so that the
* clock task can tell who to bill for system time.
*/
register struct proc *rp; /* process to run */
int q; /* iterate over queues */
NOREC_ENTER(pick);
/* Check each of the scheduling queues for ready processes. The number of
* queues is defined in proc.h, and priorities are set in the task table.
* The lowest queue contains IDLE, which is always ready.
*/
for (q=0; q < NR_SCHED_QUEUES; q++) {
int found = 0;
if(!(rp = rdy_head[q])) {
TRACE(VF_PICKPROC, printf("queue %d empty\n", q););
continue;
}
TRACE(VF_PICKPROC, printf("found %s / %d on queue %d\n",
rp->p_name, rp->p_endpoint, q););
next_ptr = rp; /* run process 'rp' next */
vmassert(proc_ptr != next_ptr);
vmassert(!next_ptr->p_rts_flags);
if (priv(rp)->s_flags & BILLABLE)
bill_ptr = rp; /* bill for system time */
NOREC_RETURN(pick, );
}
minix_panic("no runnable processes", NO_NUM);
}
/*===========================================================================*
* balance_queues *
*===========================================================================*/
#define Q_BALANCE_TICKS 100
PUBLIC void balance_queues(tp)
timer_t *tp; /* watchdog timer pointer */
{
/* Check entire process table and give all process a higher priority. This
* effectively means giving a new quantum. If a process already is at its
* maximum priority, its quantum will be renewed.
*/
static timer_t queue_timer; /* timer structure to use */
register struct proc* rp; /* process table pointer */
clock_t next_period; /* time of next period */
int ticks_added = 0; /* total time added */
vmassert(!intr_disabled());
lock;
for (rp=BEG_PROC_ADDR; rp<END_PROC_ADDR; rp++) {
if (! isemptyp(rp)) { /* check slot use */
if (rp->p_priority > rp->p_max_priority) { /* update priority? */
if (rp->p_rts_flags == 0) dequeue(rp); /* take off queue */
ticks_added += rp->p_quantum_size; /* do accounting */
rp->p_priority -= 1; /* raise priority */
if (rp->p_rts_flags == 0) enqueue(rp); /* put on queue */
}
else {
ticks_added += rp->p_quantum_size - rp->p_ticks_left;
rp->p_ticks_left = rp->p_quantum_size; /* give new quantum */
}
}
}
unlock;
/* Now schedule a new watchdog timer to balance the queues again. The
* period depends on the total amount of quantum ticks added.
*/
next_period = MAX(Q_BALANCE_TICKS, ticks_added); /* calculate next */
set_timer(&queue_timer, get_uptime() + next_period, balance_queues);
}
/*===========================================================================*
* lock_send *
*===========================================================================*/
PUBLIC int lock_send(dst_e, m_ptr)
int dst_e; /* to whom is message being sent? */
message *m_ptr; /* pointer to message buffer */
{
/* Safe gateway to mini_send() for tasks. */
int result;
lock;
result = mini_send(proc_ptr, dst_e, m_ptr, 0);
unlock;
return(result);
}
/*===========================================================================*
* endpoint_lookup *
*===========================================================================*/
PUBLIC struct proc *endpoint_lookup(endpoint_t e)
{
int n;
if(!isokendpt(e, &n)) return NULL;
return proc_addr(n);
}
/*===========================================================================*
* isokendpt_f *
*===========================================================================*/
#if DEBUG_ENABLE_IPC_WARNINGS
PUBLIC int isokendpt_f(file, line, e, p, fatalflag)
char *file;
int line;
#else
PUBLIC int isokendpt_f(e, p, fatalflag)
#endif
endpoint_t e;
int *p, fatalflag;
{
int ok = 0;
/* Convert an endpoint number into a process number.
* Return nonzero if the process is alive with the corresponding
* generation number, zero otherwise.
*
* This function is called with file and line number by the
* isokendpt_d macro if DEBUG_ENABLE_IPC_WARNINGS is defined,
* otherwise without. This allows us to print the where the
* conversion was attempted, making the errors verbose without
* adding code for that at every call.
*
* If fatalflag is nonzero, we must panic if the conversion doesn't
* succeed.
*/
*p = _ENDPOINT_P(e);
if(!isokprocn(*p)) {
#if DEBUG_ENABLE_IPC_WARNINGS
kprintf("kernel:%s:%d: bad endpoint %d: proc %d out of range\n",
file, line, e, *p);
#endif
} else if(isemptyn(*p)) {
#if 0
kprintf("kernel:%s:%d: bad endpoint %d: proc %d empty\n", file, line, e, *p);
#endif
} else if(proc_addr(*p)->p_endpoint != e) {
#if DEBUG_ENABLE_IPC_WARNINGS
kprintf("kernel:%s:%d: bad endpoint %d: proc %d has ept %d (generation %d vs. %d)\n", file, line,
e, *p, proc_addr(*p)->p_endpoint,
_ENDPOINT_G(e), _ENDPOINT_G(proc_addr(*p)->p_endpoint));
#endif
} else ok = 1;
if(!ok && fatalflag) {
minix_panic("invalid endpoint ", e);
}
return ok;
}
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