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minix/kernel/proc.c
Tomas Hruby 9e01a83636 SMP - reduced TLB flushing 
- flush TLB of processes only if the page tables has been changed and
  the page tables of this process are already loaded on this cpu which
  means that there might be stale entries in TLB. Until now SMP was
  always flushing TLB to make sure everything is consistent.
2010-10-25 16:21:23 +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
*
* 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/endpoint.h>
#include <minix/ipcconst.h>
#include <stddef.h>
#include <signal.h>
#include <minix/syslib.h>
#include <assert.h>
#include "debug.h"
#include "kernel.h"
#include "proc.h"
#include "vm.h"
#include "clock.h"
#include "spinlock.h"
#include "profile.h"
#include "arch_proto.h"
/* Scheduling and message passing functions */
FORWARD _PROTOTYPE( void idle, (void));
/**
* Made public for use in clock.c (for user-space scheduling)
FORWARD _PROTOTYPE( int mini_send, (struct proc *caller_ptr, endpoint_t dst_e,
message *m_ptr, int flags));
*/
FORWARD _PROTOTYPE( int mini_receive, (struct proc *caller_ptr, endpoint_t 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, endpoint_t src_dst_e));
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( struct proc * pick_proc, (void));
FORWARD _PROTOTYPE( void enqueue_head, (struct proc *rp));
/* all idles share the same idle_priv structure */
PRIVATE struct priv idle_priv;
PRIVATE void set_idle_name(char * name, int n)
{
int i, c;
int p_z = 0;
/*
* P_NAME_LEN limits us to 3 characters for the idle task numer. 999
* should be enough though.
*/
if (n > 999)
n = 999;
name[0] = 'i';
name[1] = 'd';
name[2] = 'l';
name[3] = 'e';
for (i = 4, c = 100; c > 0; c /= 10) {
int digit;
digit = n / c;
n -= digit * c;
if (p_z || digit != 0 || c == 1) {
p_z = 1;
name[i++] = '0' + digit;
}
}
name[i] = '\0';
}
#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; \
}
PUBLIC void proc_init(void)
{
struct proc * rp;
struct priv *sp;
int i;
/* Clear the process table. Anounce each slot as empty and set up
* mappings for proc_addr() and proc_nr() macros. Do the same for the
* table with privilege structures for the system processes.
*/
for (rp = BEG_PROC_ADDR, i = -NR_TASKS; rp < END_PROC_ADDR; ++rp, ++i) {
rp->p_rts_flags = RTS_SLOT_FREE;/* initialize free slot */
rp->p_magic = PMAGIC;
rp->p_nr = i; /* proc number from ptr */
rp->p_endpoint = _ENDPOINT(0, rp->p_nr); /* generation no. 0 */
rp->p_scheduler = NULL; /* no user space scheduler */
rp->p_priority = 0; /* no priority */
rp->p_quantum_size_ms = 0; /* no quantum size */
}
for (sp = BEG_PRIV_ADDR, i = 0; sp < END_PRIV_ADDR; ++sp, ++i) {
sp->s_proc_nr = NONE; /* initialize as free */
sp->s_id = (sys_id_t) i; /* priv structure index */
ppriv_addr[i] = sp; /* priv ptr from number */
sp->s_sig_mgr = NONE; /* clear signal managers */
sp->s_bak_sig_mgr = NONE;
}
idle_priv.s_flags = IDL_F;
/* initialize IDLE structures for every CPU */
for (i = 0; i < CONFIG_MAX_CPUS; i++) {
struct proc * ip = get_cpu_var_ptr(i, idle_proc);
ip->p_endpoint = IDLE;
ip->p_priv = &idle_priv;
/* must not let idle ever get scheduled */
ip->p_rts_flags |= RTS_PROC_STOP;
set_idle_name(ip->p_name, i);
}
for (rp = BEG_PROC_ADDR; rp < END_PROC_ADDR; ++rp) {
/*
* FXSR requires 16-byte alignment of memory image, but
* unfortunately a.out does not preserve the alignment while
* linking. Thus we have to do manual alignment.
*/
phys_bytes aligned_fp_area;
aligned_fp_area =
(phys_bytes) &rp->p_fpu_state.fpu_image;
if(aligned_fp_area % FPUALIGN) {
aligned_fp_area += FPUALIGN -
(aligned_fp_area % FPUALIGN);
}
rp->p_fpu_state.fpu_save_area_p =
(void *) aligned_fp_area;
}
}
PRIVATE void switch_address_space_idle(void)
{
#ifdef CONFIG_SMP
/*
* currently we bet that VM is always alive and its pages available so
* when the CPU wakes up the kernel is mapped and no surprises happen.
* This is only a problem if more than 1 cpus are available
*/
switch_address_space(proc_addr(VM_PROC_NR));
#endif
}
/*===========================================================================*
* idle *
*===========================================================================*/
PRIVATE void idle(void)
{
struct proc * p;
/* This function is called whenever there is no work to do.
* Halt the CPU, and measure how many timestamp counter ticks are
* spent not doing anything. This allows test setups to measure
* the CPU utiliziation of certain workloads with high precision.
*/
p = get_cpulocal_var(proc_ptr) = get_cpulocal_var_ptr(idle_proc);
if (priv(p)->s_flags & BILLABLE)
get_cpulocal_var(bill_ptr) = p;
switch_address_space_idle();
#ifdef CONFIG_SMP
/* we don't need to keep time on APs as it is handled on the BSP */
if (cpuid != bsp_cpu_id)
stop_local_timer();
get_cpulocal_var(cpu_is_idle) = 1;
#endif
/* start accounting for the idle time */
context_stop(proc_addr(KERNEL));
if (!sprofiling)
halt_cpu();
else {
volatile int * v;
v = get_cpulocal_var_ptr(idle_interrupted);
interrupts_enable();
while (!*v)
arch_pause();
interrupts_disable();
*v = 0;
}
/*
* end of accounting for the idle task does not happen here, the kernel
* is handling stuff for quite a while before it gets back here!
*/
}
/*===========================================================================*
* switch_to_user *
*===========================================================================*/
PUBLIC void switch_to_user(void)
{
/* This function is called an instant before proc_ptr is
* to be scheduled again.
*/
struct proc * p;
#ifdef CONFIG_SMP
int tlb_must_refresh = 0;
#endif
p = get_cpulocal_var(proc_ptr);
/*
* if the current process is still runnable check the misc flags and let
* it run unless it becomes not runnable in the meantime
*/
if (proc_is_runnable(p))
goto check_misc_flags;
/*
* if a process becomes not runnable while handling the misc flags, we
* need to pick a new one here and start from scratch. Also if the
* current process wasn' runnable, we pick a new one here
*/
not_runnable_pick_new:
if (proc_is_preempted(p)) {
p->p_rts_flags &= ~RTS_PREEMPTED;
if (proc_is_runnable(p)) {
if (!is_zero64(p->p_cpu_time_left))
enqueue_head(p);
else
enqueue(p);
}
}
/*
* if we have no process to run, set IDLE as the current process for
* time accounting and put the cpu in and idle state. After the next
* timer interrupt the execution resumes here and we can pick another
* process. If there is still nothing runnable we "schedule" IDLE again
*/
while (!(p = pick_proc())) {
idle();
}
/* update the global variable */
get_cpulocal_var(proc_ptr) = p;
#ifdef CONFIG_SMP
if (p->p_misc_flags & MF_FLUSH_TLB && get_cpulocal_var(ptproc) == p)
tlb_must_refresh = 1;
#endif
switch_address_space(p);
check_misc_flags:
assert(p);
assert(proc_is_runnable(p));
while (p->p_misc_flags &
(MF_KCALL_RESUME | MF_DELIVERMSG |
MF_SC_DEFER | MF_SC_TRACE | MF_SC_ACTIVE)) {
assert(proc_is_runnable(p));
if (p->p_misc_flags & MF_KCALL_RESUME) {
kernel_call_resume(p);
}
else if (p->p_misc_flags & MF_DELIVERMSG) {
TRACE(VF_SCHEDULING, printf("delivering to %s / %d\n",
p->p_name, p->p_endpoint););
delivermsg(p);
}
else if (p->p_misc_flags & MF_SC_DEFER) {
/* Perform the system call that we deferred earlier. */
assert (!(p->p_misc_flags & MF_SC_ACTIVE));
arch_do_syscall(p);
/* If the process is stopped for signal delivery, and
* not blocked sending a message after the system call,
* inform PM.
*/
if ((p->p_misc_flags & MF_SIG_DELAY) &&
!RTS_ISSET(p, RTS_SENDING))
sig_delay_done(p);
}
else if (p->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 (!(p->p_misc_flags & MF_SC_ACTIVE))
break;
p->p_misc_flags &=
~(MF_SC_TRACE | MF_SC_ACTIVE);
/* Signal the "leave system call" event.
* Block the process.
*/
cause_sig(proc_nr(p), SIGTRAP);
}
else if (p->p_misc_flags & MF_SC_ACTIVE) {
/* If MF_SC_ACTIVE was set, remove it now:
* we're leaving the system call.
*/
p->p_misc_flags &= ~MF_SC_ACTIVE;
break;
}
/*
* the selected process might not be runnable anymore. We have
* to checkit and schedule another one
*/
if (!proc_is_runnable(p))
goto not_runnable_pick_new;
}
/*
* check the quantum left before it runs again. We must do it only here
* as we are sure that a possible out-of-quantum message to the
* scheduler will not collide with the regular ipc
*/
if (is_zero64(p->p_cpu_time_left))
proc_no_time(p);
/*
* After handling the misc flags the selected process might not be
* runnable anymore. We have to checkit and schedule another one
*/
if (!proc_is_runnable(p))
goto not_runnable_pick_new;
TRACE(VF_SCHEDULING, printf("cpu %d starting %s / %d "
"pc 0x%08x\n",
cpuid, p->p_name, p->p_endpoint, p->p_reg.pc););
#if DEBUG_TRACE
p->p_schedules++;
#endif
p = arch_finish_switch_to_user();
assert(!is_zero64(p->p_cpu_time_left));
context_stop(proc_addr(KERNEL));
/* If the process isn't the owner of FPU, enable the FPU exception */
if(get_cpulocal_var(fpu_owner) != p)
enable_fpu_exception();
else
disable_fpu_exception();
/* If MF_CONTEXT_SET is set, don't clobber process state within
* the kernel. The next kernel entry is OK again though.
*/
p->p_misc_flags &= ~MF_CONTEXT_SET;
assert(!(p->p_misc_flags & MF_FULLVM) || p->p_seg.p_cr3 != 0);
#ifdef CONFIG_SMP
if (p->p_misc_flags & MF_FLUSH_TLB) {
if (tlb_must_refresh)
refresh_tlb();
p->p_misc_flags &= ~MF_FLUSH_TLB;
}
#endif
restart_local_timer();
/*
* restore_user_context() carries out the actual mode switch from kernel
* to userspace. This function does not return
*/
restore_user_context(p);
NOT_REACHABLE;
}
/*
* handler for all synchronous IPC calls
*/
PRIVATE int do_sync_ipc(struct proc * caller_ptr, /* who made the call */
int call_nr, /* system call number and flags */
endpoint_t src_dst_e, /* src or dst of the call */
message *m_ptr) /* users pointer to a message */
{
int result; /* the system call's result */
int src_dst_p; /* Process slot number */
char *callname;
/* Check 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.
*/
assert(call_nr != SENDA);
/* Only allow non-negative call_nr values less than 32 */
if (call_nr < 0 || call_nr > IPCNO_HIGHEST || call_nr >= 32
|| !(callname = ipc_call_names[call_nr])) {
#if DEBUG_ENABLE_IPC_WARNINGS
printf("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 (src_dst_e == ANY)
{
if (call_nr != RECEIVE)
{
#if 0
printf("sys_call: %s by %d with bad endpoint %d\n",
callname,
proc_nr(caller_ptr), src_dst_e);
#endif
return EINVAL;
}
src_dst_p = (int) src_dst_e;
}
else
{
/* Require a valid source and/or destination process. */
if(!isokendpt(src_dst_e, &src_dst_p)) {
#if 0
printf("sys_call: %s by %d with bad endpoint %d\n",
callname,
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
printf(
"sys_call: ipc mask denied %s from %d to %d\n",
callname,
caller_ptr->p_endpoint, src_dst_e);
#endif
return(ECALLDENIED); /* call denied by ipc mask */
}
}
}
/* 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
printf("sys_call: %s not allowed, caller %d, src_dst %d\n",
callname, proc_nr(caller_ptr), src_dst_p);
#endif
return(ETRAPDENIED); /* trap denied by mask or kernel */
}
if (call_nr != SENDREC && call_nr != RECEIVE && iskerneln(src_dst_p)) {
#if DEBUG_ENABLE_IPC_WARNINGS
printf("sys_call: trap %d not allowed, caller %d, src_dst %d\n",
callname, proc_nr(caller_ptr), src_dst_e);
#endif
return(ETRAPDENIED); /* trap denied by mask or kernel */
}
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;
IPC_STATUS_CLEAR(caller_ptr); /* clear IPC status code */
}
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;
default:
result = EBADCALL; /* illegal system call */
}
/* Now, return the result of the system call to the caller. */
return(result);
}
PUBLIC int do_ipc(reg_t r1, reg_t r2, reg_t r3)
{
struct proc *const caller_ptr = get_cpulocal_var(proc_ptr); /* get pointer to caller */
int call_nr = (int) r1;
assert(!RTS_ISSET(caller_ptr, RTS_SLOT_FREE));
/* 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;
assert (!(caller_ptr->p_misc_flags & MF_SC_ACTIVE));
/* Set a flag to allow reliable tracing of leaving the system call. */
caller_ptr->p_misc_flags |= MF_SC_ACTIVE;
}
if(caller_ptr->p_misc_flags & MF_DELIVERMSG) {
panic("sys_call: MF_DELIVERMSG on for %s / %d\n",
caller_ptr->p_name, caller_ptr->p_endpoint);
}
/* 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:
case SEND:
case RECEIVE:
case NOTIFY:
case SENDNB:
{
/* Process accounting for scheduling */
caller_ptr->p_accounting.ipc_sync++;
return do_sync_ipc(caller_ptr, call_nr, (endpoint_t) r2,
(message *) r3);
}
case SENDA:
{
/*
* Get and check the size of the argument in bytes as it is a
* table
*/
size_t msg_size = (size_t) r2;
/* Process accounting for scheduling */
caller_ptr->p_accounting.ipc_async++;
/* 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;
return mini_senda(caller_ptr, (asynmsg_t *) r3, msg_size);
}
default:
return EBADCALL; /* illegal system call */
}
}
/*===========================================================================*
* deadlock *
*===========================================================================*/
PRIVATE int deadlock(function, cp, src_dst_e)
int function; /* trap number */
register struct proc *cp; /* pointer to caller */
endpoint_t src_dst_e; /* 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 */
#if DEBUG_ENABLE_IPC_WARNINGS
static struct proc *processes[NR_PROCS + NR_TASKS];
processes[0] = cp;
#endif
while (src_dst_e != ANY) { /* check while process nr */
int src_dst_slot;
okendpt(src_dst_e, &src_dst_slot);
xp = proc_addr(src_dst_slot); /* follow chain of processes */
assert(proc_ptr_ok(xp));
assert(!RTS_ISSET(xp, RTS_SLOT_FREE));
#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((src_dst_e = P_BLOCKEDON(xp)) == NONE)
return 0;
/* 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_e == cp->p_endpoint) { /* 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)) & RTS_SENDING) {
return(0); /* not a deadlock */
}
}
#if DEBUG_ENABLE_IPC_WARNINGS
{
int i;
printf("deadlock between these processes:\n");
for(i = 0; i < group_size; i++) {
printf(" %10s ", processes[i]->p_name);
}
printf("\n\n");
for(i = 0; i < group_size; i++) {
print_proc(processes[i]);
proc_stacktrace(processes[i]);
}
}
#endif
return(group_size); /* deadlock found */
}
}
return(0); /* not a deadlock */
}
/*===========================================================================*
* mini_send *
*===========================================================================*/
PUBLIC int mini_send(
register struct proc *caller_ptr, /* who is trying to send a message? */
endpoint_t dst_e, /* to whom is message being sent? */
message *m_ptr, /* pointer to message buffer */
const 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;
dst_p = _ENDPOINT_P(dst_e);
dst_ptr = proc_addr(dst_p);
if (RTS_ISSET(dst_ptr, RTS_NO_ENDPOINT))
{
return EDEADSRCDST;
}
/* Check if 'dst' is blocked waiting for this message. The destination's
* RTS_SENDING flag may be set when its SENDREC call blocked while sending.
*/
if (WILLRECEIVE(dst_ptr, caller_ptr->p_endpoint)) {
int call;
/* Destination is indeed waiting for this message. */
assert(!(dst_ptr->p_misc_flags & MF_DELIVERMSG));
if (!(flags & FROM_KERNEL)) {
if(copy_msg_from_user(caller_ptr, m_ptr, &dst_ptr->p_delivermsg))
return EFAULT;
} else {
dst_ptr->p_delivermsg = *m_ptr;
IPC_STATUS_ADD_FLAGS(dst_ptr, IPC_FLG_MSG_FROM_KERNEL);
}
dst_ptr->p_delivermsg.m_source = caller_ptr->p_endpoint;
dst_ptr->p_misc_flags |= MF_DELIVERMSG;
call = (caller_ptr->p_misc_flags & MF_REPLY_PEND ? SENDREC
: (flags & NON_BLOCKING ? SENDNB : SEND));
IPC_STATUS_ADD_CALL(dst_ptr, call);
if (dst_ptr->p_misc_flags & MF_REPLY_PEND)
dst_ptr->p_misc_flags &= ~MF_REPLY_PEND;
RTS_UNSET(dst_ptr, RTS_RECEIVING);
#if DEBUG_DUMPIPC
printmsgsend(&dst_ptr->p_delivermsg, caller_ptr, dst_ptr);
printmsgrecv(&dst_ptr->p_delivermsg, caller_ptr, dst_ptr);
#endif
} else {
if(flags & NON_BLOCKING) {
return(ENOTREADY);
}
/* Check for a possible deadlock before actually blocking. */
if (deadlock(SEND, caller_ptr, dst_e)) {
return(ELOCKED);
}
/* Destination is not waiting. Block and dequeue caller. */
if (!(flags & FROM_KERNEL)) {
if(copy_msg_from_user(caller_ptr, m_ptr, &caller_ptr->p_sendmsg))
return EFAULT;
} else {
caller_ptr->p_sendmsg = *m_ptr;
/*
* we need to remember that this message is from kernel so we
* can set the delivery status flags when the message is
* actually delivered
*/
caller_ptr->p_misc_flags |= MF_SENDING_FROM_KERNEL;
}
RTS_SET(caller_ptr, RTS_SENDING);
caller_ptr->p_sendto_e = dst_e;
/* Process is now blocked. Put in on the destination's queue. */
assert(caller_ptr->p_q_link == NULL);
xpp = &dst_ptr->p_caller_q; /* find end of list */
while (*xpp) xpp = &(*xpp)->p_q_link;
*xpp = caller_ptr; /* add caller to end */
#if DEBUG_DUMPIPC
printmsgsend(&caller_ptr->p_sendmsg, caller_ptr, dst_ptr);
#endif
}
return(OK);
}
/*===========================================================================*
* mini_receive *
*===========================================================================*/
PRIVATE int mini_receive(struct proc * caller_ptr,
endpoint_t src_e, /* which message source is wanted */
message * m_buff_usr, /* pointer to message buffer */
const 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;
sys_map_t *map;
bitchunk_t *chunk;
int i, r, src_id, src_proc_nr, src_p;
assert(!(caller_ptr->p_misc_flags & MF_DELIVERMSG));
/* This is where we want our message. */
caller_ptr->p_delivermsg_vir = (vir_bytes) m_buff_usr;
if(src_e == ANY) src_p = ANY;
else
{
okendpt(src_e, &src_p);
if (RTS_ISSET(proc_addr(src_p), RTS_NO_ENDPOINT))
{
return EDEADSRCDST;
}
}
/* Check to see if a message from desired source is already available. The
* caller's RTS_SENDING flag may be set if SENDREC couldn't send. If it is
* set, the process should be blocked.
*/
if (!RTS_ISSET(caller_ptr, RTS_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) {
printf("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. */
hisep = proc_addr(src_proc_nr)->p_endpoint;
assert(!(caller_ptr->p_misc_flags & MF_DELIVERMSG));
assert(src_e == ANY || hisep == src_e);
/* assemble message */
BuildNotifyMessage(&caller_ptr->p_delivermsg, src_proc_nr, caller_ptr);
caller_ptr->p_delivermsg.m_source = hisep;
caller_ptr->p_misc_flags |= MF_DELIVERMSG;
IPC_STATUS_ADD_CALL(caller_ptr, NOTIFY);
goto receive_done;
}
}
/* Check if there are pending senda(). */
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) {
IPC_STATUS_ADD_CALL(caller_ptr, SENDA);
goto receive_done;
}
}
/* Check caller queue. Use pointer pointers to keep code simple. */
xpp = &caller_ptr->p_caller_q;
while (*xpp) {
struct proc * sender = *xpp;
if (src_e == ANY || src_p == proc_nr(sender)) {
int call;
assert(!RTS_ISSET(sender, RTS_SLOT_FREE));
assert(!RTS_ISSET(sender, RTS_NO_ENDPOINT));
/* Found acceptable message. Copy it and update status. */
assert(!(caller_ptr->p_misc_flags & MF_DELIVERMSG));
caller_ptr->p_delivermsg = sender->p_sendmsg;
caller_ptr->p_delivermsg.m_source = sender->p_endpoint;
caller_ptr->p_misc_flags |= MF_DELIVERMSG;
RTS_UNSET(sender, RTS_SENDING);
call = (sender->p_misc_flags & MF_REPLY_PEND ? SENDREC : SEND);
IPC_STATUS_ADD_CALL(caller_ptr, call);
/*
* if the message is originaly from the kernel on behalf of this
* process, we must send the status flags accordingly
*/
if (sender->p_misc_flags & MF_SENDING_FROM_KERNEL) {
IPC_STATUS_ADD_FLAGS(caller_ptr, IPC_FLG_MSG_FROM_KERNEL);
/* we can clean the flag now, not need anymore */
sender->p_misc_flags &= ~MF_SENDING_FROM_KERNEL;
}
if (sender->p_misc_flags & MF_SIG_DELAY)
sig_delay_done(sender);
#if DEBUG_DUMPIPC
printmsgrecv(&caller_ptr->p_delivermsg, *xpp, caller_ptr);
#endif
*xpp = sender->p_q_link; /* remove from queue */
sender->p_q_link = NULL;
goto receive_done;
}
xpp = &sender->p_q_link; /* proceed to next */
}
}
/* 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)) {
/* Check for a possible deadlock before actually blocking. */
if (deadlock(RECEIVE, caller_ptr, src_e)) {
return(ELOCKED);
}
caller_ptr->p_getfrom_e = src_e;
RTS_SET(caller_ptr, RTS_RECEIVING);
return(OK);
} else {
return(ENOTREADY);
}
receive_done:
if (caller_ptr->p_misc_flags & MF_REPLY_PEND)
caller_ptr->p_misc_flags &= ~MF_REPLY_PEND;
return OK;
}
/*===========================================================================*
* mini_notify *
*===========================================================================*/
PUBLIC int mini_notify(
const 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 */
int dst_p;
if (!isokendpt(dst_e, &dst_p)) {
util_stacktrace();
printf("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.
*/
assert(!(dst_ptr->p_misc_flags & MF_DELIVERMSG));
BuildNotifyMessage(&dst_ptr->p_delivermsg, proc_nr(caller_ptr), dst_ptr);
dst_ptr->p_delivermsg.m_source = caller_ptr->p_endpoint;
dst_ptr->p_misc_flags |= MF_DELIVERMSG;
IPC_STATUS_ADD_CALL(dst_ptr, NOTIFY);
RTS_UNSET(dst_ptr, RTS_RECEIVING);
return(OK);
}
/* Destination is not ready to receive the notification. Add it to the
* bit map with pending notifications. Note the indirectness: the privilege 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) \
printf("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),\
KERNEL, (vir_bytes) &tabent.field, \
sizeof(tabent.field)) != OK) {\
ASCOMPLAIN(caller_ptr, entry, #field); \
return EFAULT; \
}
#define A_INSERT(entry, field) \
if(data_copy(KERNEL, (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(struct proc *caller_ptr, asynmsg_t *table, size_t size)
{
int i, dst_p, done, do_notify;
unsigned flags;
struct proc *dst_ptr;
struct priv *privp;
asynmsg_t tabent;
const vir_bytes table_v = (vir_bytes) table;
privp= priv(caller_ptr);
if (!(privp->s_flags & SYS_PROC))
{
printf(
"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;
}
/* 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 (iskerneln(dst_p))
{
/* Asynchronous sends to the kernel are not allowed */
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 (!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
printf("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);
/* RTS_NO_ENDPOINT should be removed */
if (RTS_ISSET(dst_ptr, RTS_NO_ENDPOINT))
{
tabent.result= EDEADSRCDST;
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. */
/* Copy message from sender. */
if(copy_msg_from_user(caller_ptr, &table[i].msg,
&dst_ptr->p_delivermsg))
tabent.result = EFAULT;
else {
dst_ptr->p_delivermsg.m_source = caller_ptr->p_endpoint;
dst_ptr->p_misc_flags |= MF_DELIVERMSG;
IPC_STATUS_ADD_CALL(dst_ptr, SENDA);
RTS_UNSET(dst_ptr, RTS_RECEIVING);
tabent.result = OK;
}
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)
printf("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);
assert(!(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(struct proc *src_ptr, struct proc *dst_ptr, int *postponed)
{
int i, done;
unsigned flags;
size_t size;
endpoint_t dst_e;
struct priv *privp;
asynmsg_t tabent;
vir_bytes table_v;
struct proc *caller_ptr;
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 */
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))
{
printf("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 */
A_RETRIEVE(i, msg);
dst_ptr->p_delivermsg = tabent.msg;
dst_ptr->p_delivermsg.m_source = src_ptr->p_endpoint;
dst_ptr->p_misc_flags |= MF_DELIVERMSG;
tabent.result = OK;
A_INSERT(i, result);
tabent.flags= flags | AMF_DONE;
A_INSERT(i, flags);
if (flags & AMF_NOTIFY)
{
printf("try_one: should notify caller\n");
}
return OK;
}
if (done)
privp->s_asynsize= 0;
return EAGAIN;
}
/*===========================================================================*
* enqueue *
*===========================================================================*/
PUBLIC void enqueue(
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().
*
* This function can be used x-cpu as it always uses the queues of the cpu the
* process is assigned to.
*/
int q = rp->p_priority; /* scheduling queue to use */
struct proc **rdy_head, **rdy_tail;
assert(proc_is_runnable(rp));
assert(q >= 0);
rdy_head = get_cpu_var(rp->p_cpu, run_q_head);
rdy_tail = get_cpu_var(rp->p_cpu, run_q_tail);
/* Now add the process to the queue. */
if (!rdy_head[q]) { /* add to empty queue */
rdy_head[q] = rdy_tail[q] = rp; /* create a new queue */
rp->p_nextready = NULL; /* mark new end */
}
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 = NULL; /* mark new end */
}
if (cpuid == rp->p_cpu) {
/*
* enqueueing a process with a higher priority than the current one,
* it gets preempted. The current process must be preemptible. Testing
* the priority also makes sure that a process does not preempt itself
*/
struct proc * p;
p = get_cpulocal_var(proc_ptr);
assert(p);
if((p->p_priority > rp->p_priority) &&
(priv(p)->s_flags & PREEMPTIBLE))
RTS_SET(p, RTS_PREEMPTED); /* calls dequeue() */
}
#ifdef CONFIG_SMP
/*
* if the process was enqueued on a different cpu and the cpu is idle, i.e.
* the time is off, we need to wake up that cpu and let it schedule this new
* process
*/
else if (get_cpu_var(rp->p_cpu, cpu_is_idle)) {
smp_schedule(rp->p_cpu);
}
#endif
/* Make note of when this process was added to queue */
read_tsc_64(&(get_cpulocal_var(proc_ptr)->p_accounting.enter_queue));
#if DEBUG_SANITYCHECKS
assert(runqueues_ok_local());
#endif
}
/*===========================================================================*
* enqueue_head *
*===========================================================================*/
/*
* put a process at the front of its run queue. It comes handy when a process is
* preempted and removed from run queue to not to have a currently not-runnable
* process on a run queue. We have to put this process back at the fron to be
* fair
*/
PRIVATE void enqueue_head(struct proc *rp)
{
const int q = rp->p_priority; /* scheduling queue to use */
struct proc **rdy_head, **rdy_tail;
assert(proc_ptr_ok(rp));
assert(proc_is_runnable(rp));
/*
* the process was runnable without its quantum expired when dequeued. A
* process with no time left should vahe been handled else and differently
*/
assert(!is_zero64(rp->p_cpu_time_left));
assert(q >= 0);
rdy_head = get_cpu_var(rp->p_cpu, run_q_head);
rdy_tail = get_cpu_var(rp->p_cpu, run_q_tail);
/* Now add the process to the queue. */
if (!rdy_head[q]) { /* add to empty queue */
rdy_head[q] = rdy_tail[q] = rp; /* create a new queue */
rp->p_nextready = NULL; /* mark new end */
}
else /* add to head of queue */
rp->p_nextready = rdy_head[q]; /* chain head of queue */
rdy_head[q] = rp; /* set new queue head */
/* Make note of when this process was added to queue */
read_tsc_64(&(get_cpulocal_var(proc_ptr->p_accounting.enter_queue)));
/* Process accounting for scheduling */
rp->p_accounting.dequeues--;
rp->p_accounting.preempted++;
#if DEBUG_SANITYCHECKS
assert(runqueues_ok_local());
#endif
}
/*===========================================================================*
* dequeue *
*===========================================================================*/
PUBLIC void dequeue(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().
*
* This function can operate x-cpu as it always removes the process from the
* queue of the cpu the process is currently assigned to.
*/
int q = rp->p_priority; /* queue to use */
struct proc **xpp; /* iterate over queue */
struct proc *prev_xp;
u64_t tsc, tsc_delta;
struct proc **rdy_tail;
assert(proc_ptr_ok(rp));
assert(!proc_is_runnable(rp));
/* Side-effect for kernel: check if the task's stack still is ok? */
assert (!iskernelp(rp) || *priv(rp)->s_stack_guard == STACK_GUARD);
rdy_tail = get_cpu_var(rp->p_cpu, run_q_tail);
/* 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 = NULL;
for (xpp = get_cpu_var_ptr(rp->p_cpu, run_q_head[q]); *xpp;
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 */
}
break;
}
prev_xp = *xpp; /* save previous in chain */
}
/* Process accounting for scheduling */
rp->p_accounting.dequeues++;
/* this is not all that accurate on virtual machines, especially with
IO bound processes that only spend a short amount of time in the queue
at a time. */
if (!is_zero64(rp->p_accounting.enter_queue)) {
read_tsc_64(&tsc);
tsc_delta = sub64(tsc, rp->p_accounting.enter_queue);
rp->p_accounting.time_in_queue = add64(rp->p_accounting.time_in_queue,
tsc_delta);
make_zero64(rp->p_accounting.enter_queue);
}
#if DEBUG_SANITYCHECKS
assert(runqueues_ok_local());
#endif
}
/*===========================================================================*
* pick_proc *
*===========================================================================*/
PRIVATE struct proc * pick_proc(void)
{
/* Decide who to run now. A new process is selected an returned.
* When a billable process is selected, record it in 'bill_ptr', so that the
* clock task can tell who to bill for system time.
*
* This functions always uses the run queues of the local cpu!
*/
register struct proc *rp; /* process to run */
struct proc **rdy_head;
int q; /* iterate over queues */
/* 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.
*/
rdy_head = get_cpulocal_var(run_q_head);
for (q=0; q < NR_SCHED_QUEUES; q++) {
if(!(rp = rdy_head[q])) {
TRACE(VF_PICKPROC, printf("cpu %d queue %d empty\n", cpuid, q););
continue;
}
assert(proc_is_runnable(rp));
if (priv(rp)->s_flags & BILLABLE)
get_cpulocal_var(bill_ptr) = rp; /* bill for system time */
return rp;
}
return NULL;
}
/*===========================================================================*
* 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)
const char *file;
int line;
#else
PUBLIC int isokendpt_f(e, p, fatalflag)
#endif
endpoint_t e;
int *p;
const int 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
printf("kernel:%s:%d: bad endpoint %d: proc %d out of range\n",
file, line, e, *p);
#endif
} else if(isemptyn(*p)) {
#if 0
printf("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
printf("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) {
panic("invalid endpoint: %d", e);
}
return ok;
}
PRIVATE void notify_scheduler(struct proc *p)
{
message m_no_quantum;
int err;
assert(!proc_kernel_scheduler(p));
/* dequeue the process */
RTS_SET(p, RTS_NO_QUANTUM);
/*
* Notify the process's scheduler that it has run out of
* quantum. This is done by sending a message to the scheduler
* on the process's behalf
*/
m_no_quantum.m_source = p->p_endpoint;
m_no_quantum.m_type = SCHEDULING_NO_QUANTUM;
m_no_quantum.SCHEDULING_ACNT_QUEUE = cpu_time_2_ms(p->p_accounting.time_in_queue);
m_no_quantum.SCHEDULING_ACNT_DEQS = p->p_accounting.dequeues;
m_no_quantum.SCHEDULING_ACNT_IPC_SYNC = p->p_accounting.ipc_sync;
m_no_quantum.SCHEDULING_ACNT_IPC_ASYNC = p->p_accounting.ipc_async;
m_no_quantum.SCHEDULING_ACNT_PREEMPT = p->p_accounting.preempted;
m_no_quantum.SCHEDULING_ACNT_CPU = cpuid;
m_no_quantum.SCHEDULING_ACNT_CPU_LOAD = cpu_load();
/* Reset accounting */
reset_proc_accounting(p);
if ((err = mini_send(p, p->p_scheduler->p_endpoint,
&m_no_quantum, FROM_KERNEL))) {
panic("WARNING: Scheduling: mini_send returned %d\n", err);
}
}
PUBLIC void proc_no_time(struct proc * p)
{
if (!proc_kernel_scheduler(p) && priv(p)->s_flags & PREEMPTIBLE) {
/* this dequeues the process */
notify_scheduler(p);
}
else {
/*
* non-preemptible processes only need their quantum to
* be renewed. In fact, they by pass scheduling
*/
p->p_cpu_time_left = ms_2_cpu_time(p->p_quantum_size_ms);
#if DEBUG_RACE
RTS_SET(proc_ptr, RTS_PREEMPTED);
RTS_UNSET(proc_ptr, RTS_PREEMPTED);
#endif
}
}
PUBLIC void reset_proc_accounting(struct proc *p)
{
p->p_accounting.preempted = 0;
p->p_accounting.ipc_sync = 0;
p->p_accounting.ipc_async = 0;
p->p_accounting.dequeues = 0;
make_zero64(p->p_accounting.time_in_queue);
make_zero64(p->p_accounting.enter_queue);
}
PUBLIC void copr_not_available_handler(void)
{
struct proc * p;
struct proc ** local_fpu_owner;
/*
* Disable the FPU exception (both for the kernel and for the process
* once it's scheduled), and initialize or restore the FPU state.
*/
disable_fpu_exception();
p = get_cpulocal_var(proc_ptr);
/* if FPU is not owned by anyone, do not store anything */
local_fpu_owner = get_cpulocal_var_ptr(fpu_owner);
if (*local_fpu_owner != NULL) {
assert(*local_fpu_owner != p);
save_local_fpu(*local_fpu_owner);
}
/*
* restore the current process' state and let it run again, do not
* schedule!
*/
restore_fpu(p);
*local_fpu_owner = p;
context_stop(proc_addr(KERNEL));
restore_user_context(p);
NOT_REACHABLE;
}
PUBLIC void release_fpu(struct proc * p) {
struct proc ** fpu_owner_ptr;
fpu_owner_ptr = get_cpu_var_ptr(p->p_cpu, fpu_owner);
if (*fpu_owner_ptr == p)
*fpu_owner_ptr = NULL;
}
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