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minix/servers/pm/main.c
David van Moolenbroek b423d7b477 Merge of David's ptrace branch. Summary: 
o Support for ptrace T_ATTACH/T_DETACH and T_SYSCALL
o PM signal handling logic should now work properly, even with debuggers
  being present
o Asynchronous PM/VFS protocol, full IPC support for senda(), and
  AMF_NOREPLY senda() flag

DETAILS

Process stop and delay call handling of PM:
o Added sys_runctl() kernel call with sys_stop() and sys_resume()
  aliases, for PM to stop and resume a process
o Added exception for sending/syscall-traced processes to sys_runctl(),
  and matching SIGKREADY pseudo-signal to PM
o Fixed PM signal logic to deal with requests from a process after
  stopping it (so-called "delay calls"), using the SIGKREADY facility
o Fixed various PM panics due to race conditions with delay calls versus
  VFS calls
o Removed special PRIO_STOP priority value
o Added SYS_LOCK RTS kernel flag, to stop an individual process from
  running while modifying its process structure

Signal and debugger handling in PM:
o Fixed debugger signals being dropped if a second signal arrives when
  the debugger has not retrieved the first one
o Fixed debugger signals being sent to the debugger more than once
o Fixed debugger signals unpausing process in VFS; removed PM_UNPAUSE_TR
  protocol message
o Detached debugger signals from general signal logic and from being
  blocked on VFS calls, meaning that even VFS can now be traced
o Fixed debugger being unable to receive more than one pending signal in
  one process stop
o Fixed signal delivery being delayed needlessly when multiple signals
  are pending
o Fixed wait test for tracer, which was returning for children that were
  not waited for
o Removed second parallel pending call from PM to VFS for any process
o Fixed process becoming runnable between exec() and debugger trap
o Added support for notifying the debugger before the parent when a
  debugged child exits
o Fixed debugger death causing child to remain stopped forever
o Fixed consistently incorrect use of _NSIG

Extensions to ptrace():
o Added T_ATTACH and T_DETACH ptrace request, to attach and detach a
  debugger to and from a process
o Added T_SYSCALL ptrace request, to trace system calls
o Added T_SETOPT ptrace request, to set trace options
o Added TO_TRACEFORK trace option, to attach automatically to children
  of a traced process
o Added TO_ALTEXEC trace option, to send SIGSTOP instead of SIGTRAP upon
  a successful exec() of the tracee
o Extended T_GETUSER ptrace support to allow retrieving a process's priv
  structure
o Removed T_STOP ptrace request again, as it does not help implementing
  debuggers properly
o Added MINIX3-specific ptrace test (test42)
o Added proper manual page for ptrace(2)

Asynchronous PM/VFS interface:
o Fixed asynchronous messages not being checked when receive() is called
  with an endpoint other than ANY
o Added AMF_NOREPLY senda() flag, preventing such messages from
  satisfying the receive part of a sendrec()
o Added asynsend3() that takes optional flags; asynsend() is now a
  #define passing in 0 as third parameter
o Made PM/VFS protocol asynchronous; reintroduced tell_fs()
o Made PM_BASE request/reply number range unique
o Hacked in a horrible temporary workaround into RS to deal with newly
  revealed RS-PM-VFS race condition triangle until VFS is asynchronous

System signal handling:
o Fixed shutdown logic of device drivers; removed old SIGKSTOP signal
o Removed is-superuser check from PM's do_procstat() (aka getsigset())
o Added sigset macros to allow system processes to deal with the full
  signal set, rather than just the POSIX subset

Miscellaneous PM fixes:
o Split do_getset into do_get and do_set, merging common code and making
  structure clearer
o Fixed setpriority() being able to put to sleep processes using an
  invalid parameter, or revive zombie processes
o Made find_proc() global; removed obsolete proc_from_pid()
o Cleanup here and there

Also included:
o Fixed false-positive boot order kernel warning
o Removed last traces of old NOTIFY_FROM code

THINGS OF POSSIBLE INTEREST

o It should now be possible to run PM at any priority, even lower than
  user processes
o No assumptions are made about communication speed between PM and VFS,
  although communication must be FIFO
o A debugger will now receive incoming debuggee signals at kill time
  only; the process may not yet be fully stopped
o A first step has been made towards making the SYSTEM task preemptible
2009-09-30 09:57:22 +00:00

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/* This file contains the main program of the process manager and some related
* procedures. When MINIX starts up, the kernel runs for a little while,
* initializing itself and its tasks, and then it runs PM and FS. Both PM
* and FS initialize themselves as far as they can. PM asks the kernel for
* all free memory and starts serving requests.
*
* The entry points into this file are:
* main: starts PM running
* setreply: set the reply to be sent to process making an PM system call
*/
#include "pm.h"
#include <minix/keymap.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/ds.h>
#include <minix/type.h>
#include <minix/endpoint.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <minix/vm.h>
#include <minix/crtso.h>
#include <signal.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/resource.h>
#include <sys/utsname.h>
#include <string.h>
#include <archconst.h>
#include <archtypes.h>
#include <env.h>
#include "mproc.h"
#include "param.h"
#include "../../kernel/const.h"
#include "../../kernel/config.h"
#include "../../kernel/proc.h"
#if ENABLE_SYSCALL_STATS
EXTERN unsigned long calls_stats[NCALLS];
#endif
FORWARD _PROTOTYPE( void get_work, (void) );
FORWARD _PROTOTYPE( void pm_init, (void) );
FORWARD _PROTOTYPE( int get_nice_value, (int queue) );
FORWARD _PROTOTYPE( void handle_fs_reply, (void) );
#define click_to_round_k(n) \
((unsigned) ((((unsigned long) (n) << CLICK_SHIFT) + 512) / 1024))
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC int main()
{
/* Main routine of the process manager. */
int result, s, proc_nr;
struct mproc *rmp;
sigset_t sigset;
pm_init(); /* initialize process manager tables */
/* This is PM's main loop- get work and do it, forever and forever. */
while (TRUE) {
get_work(); /* wait for an PM system call */
/* Drop delayed calls from exiting processes. */
if (mp->mp_flags & EXITING)
continue;
/* Check for system notifications first. Special cases. */
if (is_notify(call_nr)) {
switch(who_p) {
case CLOCK:
pm_expire_timers(m_in.NOTIFY_TIMESTAMP);
result = SUSPEND; /* don't reply */
break;
case SYSTEM: /* signals pending */
sigset = m_in.NOTIFY_ARG;
if (sigismember(&sigset, SIGKSIG)) {
(void) ksig_pending();
}
result = SUSPEND; /* don't reply */
break;
default :
result = ENOSYS;
}
/* done, send reply and continue */
goto send_reply;
}
switch(call_nr)
{
case PM_SETUID_REPLY:
case PM_SETGID_REPLY:
case PM_SETSID_REPLY:
case PM_EXEC_REPLY:
case PM_EXIT_REPLY:
case PM_CORE_REPLY:
case PM_FORK_REPLY:
case PM_FORK_NB_REPLY:
case PM_UNPAUSE_REPLY:
case PM_REBOOT_REPLY:
if (who_e == FS_PROC_NR)
{
handle_fs_reply();
result= SUSPEND; /* don't reply */
}
else
result= ENOSYS;
break;
case ALLOCMEM:
result= do_allocmem();
break;
case FORK_NB:
result= do_fork_nb();
break;
case EXEC_NEWMEM:
result= exec_newmem();
break;
case EXEC_RESTART:
result= do_execrestart();
break;
case PROCSTAT:
result= do_procstat();
break;
case GETPROCNR:
result= do_getprocnr();
break;
case GETPUID:
result= do_getpuid();
break;
default:
/* Else, if the system call number is valid, perform the
* call.
*/
if ((unsigned) call_nr >= NCALLS) {
result = ENOSYS;
} else {
#if ENABLE_SYSCALL_STATS
calls_stats[call_nr]++;
#endif
result = (*call_vec[call_nr])();
}
break;
}
send_reply:
/* Send the results back to the user to indicate completion. */
if (result != SUSPEND) setreply(who_p, result);
/* Send out all pending reply messages, including the answer to
* the call just made above.
*/
for (proc_nr=0, rmp=mproc; proc_nr < NR_PROCS; proc_nr++, rmp++) {
/* In the meantime, the process may have been killed by a
* signal (e.g. if a lethal pending signal was unblocked)
* without the PM realizing it. If the slot is no longer in
* use or the process is exiting, don't try to reply.
*/
if ((rmp->mp_flags & (REPLY | IN_USE | EXITING)) ==
(REPLY | IN_USE)) {
s=sendnb(rmp->mp_endpoint, &rmp->mp_reply);
if (s != OK) {
printf("PM can't reply to %d (%s): %d\n",
rmp->mp_endpoint, rmp->mp_name, s);
}
rmp->mp_flags &= ~REPLY;
}
}
}
return(OK);
}
/*===========================================================================*
* get_work *
*===========================================================================*/
PRIVATE void get_work()
{
/* Wait for the next message and extract useful information from it. */
if (receive(ANY, &m_in) != OK)
panic(__FILE__,"PM receive error", NO_NUM);
who_e = m_in.m_source; /* who sent the message */
if(pm_isokendpt(who_e, &who_p) != OK)
panic(__FILE__, "PM got message from invalid endpoint", who_e);
call_nr = m_in.m_type; /* system call number */
/* Process slot of caller. Misuse PM's own process slot if the kernel is
* calling. This can happen in case of synchronous alarms (CLOCK) or or
* event like pending kernel signals (SYSTEM).
*/
mp = &mproc[who_p < 0 ? PM_PROC_NR : who_p];
if(who_p >= 0 && mp->mp_endpoint != who_e) {
panic(__FILE__, "PM endpoint number out of sync with source",
mp->mp_endpoint);
}
}
/*===========================================================================*
* setreply *
*===========================================================================*/
PUBLIC void setreply(proc_nr, result)
int proc_nr; /* process to reply to */
int result; /* result of call (usually OK or error #) */
{
/* Fill in a reply message to be sent later to a user process. System calls
* may occasionally fill in other fields, this is only for the main return
* value, and for setting the "must send reply" flag.
*/
register struct mproc *rmp = &mproc[proc_nr];
if(proc_nr < 0 || proc_nr >= NR_PROCS)
panic(__FILE__,"setreply arg out of range", proc_nr);
rmp->mp_reply.reply_res = result;
rmp->mp_flags |= REPLY; /* reply pending */
}
extern int unmap_ok;
/*===========================================================================*
* pm_init *
*===========================================================================*/
PRIVATE void pm_init()
{
int failed = 0;
int f = 0;
/* Initialize the process manager.
* Memory use info is collected from the boot monitor, the kernel, and
* all processes compiled into the system image. Initially this information
* is put into an array mem_chunks. Elements of mem_chunks are struct memory,
* and hold base, size pairs in units of clicks. This array is small, there
* should be no more than 8 chunks. After the array of chunks has been built
* the contents are used to initialize the hole list. Space for the hole list
* is reserved as an array with twice as many elements as the maximum number
* of processes allowed. It is managed as a linked list, and elements of the
* array are struct hole, which, in addition to storage for a base and size in
* click units also contain space for a link, a pointer to another element.
*/
int s;
static struct boot_image image[NR_BOOT_PROCS];
register struct boot_image *ip;
static char core_sigs[] = { SIGQUIT, SIGILL, SIGTRAP, SIGABRT,
SIGEMT, SIGFPE, SIGBUS, SIGSEGV };
static char ign_sigs[] = { SIGCHLD, SIGWINCH, SIGCONT };
static char mess_sigs[] = { SIGTERM, SIGHUP, SIGABRT, SIGQUIT };
register struct mproc *rmp;
register char *sig_ptr;
message mess;
/* Initialize process table, including timers. */
for (rmp=&mproc[0]; rmp<&mproc[NR_PROCS]; rmp++) {
tmr_inittimer(&rmp->mp_timer);
}
/* Build the set of signals which cause core dumps, and the set of signals
* that are by default ignored.
*/
sigemptyset(&core_sset);
for (sig_ptr = core_sigs; sig_ptr < core_sigs+sizeof(core_sigs); sig_ptr++)
sigaddset(&core_sset, *sig_ptr);
sigemptyset(&ign_sset);
for (sig_ptr = ign_sigs; sig_ptr < ign_sigs+sizeof(ign_sigs); sig_ptr++)
sigaddset(&ign_sset, *sig_ptr);
/* Obtain a copy of the boot monitor parameters and the kernel info struct.
* Parse the list of free memory chunks. This list is what the boot monitor
* reported, but it must be corrected for the kernel and system processes.
*/
if ((s=sys_getmonparams(monitor_params, sizeof(monitor_params))) != OK)
panic(__FILE__,"get monitor params failed",s);
if ((s=sys_getkinfo(&kinfo)) != OK)
panic(__FILE__,"get kernel info failed",s);
/* Initialize PM's process table. Request a copy of the system image table
* that is defined at the kernel level to see which slots to fill in.
*/
if (OK != (s=sys_getimage(image)))
panic(__FILE__,"couldn't get image table: %d\n", s);
procs_in_use = 0; /* start populating table */
for (ip = &image[0]; ip < &image[NR_BOOT_PROCS]; ip++) {
if (ip->proc_nr >= 0) { /* task have negative nrs */
procs_in_use += 1; /* found user process */
/* Set process details found in the image table. */
rmp = &mproc[ip->proc_nr];
strncpy(rmp->mp_name, ip->proc_name, PROC_NAME_LEN);
#if 0
rmp->mp_parent = RS_PROC_NR;
#endif
rmp->mp_nice = get_nice_value(ip->priority);
sigemptyset(&rmp->mp_sig2mess);
sigemptyset(&rmp->mp_ignore);
sigemptyset(&rmp->mp_sigmask);
sigemptyset(&rmp->mp_catch);
if (ip->proc_nr == INIT_PROC_NR) { /* user process */
rmp->mp_procgrp = rmp->mp_pid = INIT_PID;
rmp->mp_flags |= IN_USE;
}
else { /* system process */
rmp->mp_pid = get_free_pid();
rmp->mp_flags |= IN_USE | PRIV_PROC;
for (sig_ptr = mess_sigs;
sig_ptr < mess_sigs+sizeof(mess_sigs);
sig_ptr++)
sigaddset(&rmp->mp_sig2mess, *sig_ptr);
}
/* Get kernel endpoint identifier. */
rmp->mp_endpoint = ip->endpoint;
/* Tell FS about this system process. */
mess.PR_SLOT = ip->proc_nr;
mess.PR_PID = rmp->mp_pid;
mess.PR_ENDPT = rmp->mp_endpoint;
if (OK != (s=send(FS_PROC_NR, &mess)))
panic(__FILE__,"can't sync up with FS", s);
/* Register proces with ds */
s= ds_publish_u32(rmp->mp_name, rmp->mp_endpoint);
if (s != OK)
failed++;
}
}
if(failed > 0)
printf("PM: failed to register %d/%d boot processes\n",
failed, NR_BOOT_PROCS);
/* Override some details. INIT, PM, FS and RS are somewhat special. */
mproc[PM_PROC_NR].mp_pid = PM_PID; /* PM has magic pid */
#if 0
mproc[RS_PROC_NR].mp_parent = INIT_PROC_NR; /* INIT is root */
#endif
sigfillset(&mproc[PM_PROC_NR].mp_ignore); /* guard against signals */
/* Tell FS that no more system processes follow and synchronize. */
mess.PR_ENDPT = NONE;
if (sendrec(FS_PROC_NR, &mess) != OK || mess.m_type != OK)
panic(__FILE__,"can't sync up with FS", NO_NUM);
#if (CHIP == INTEL)
uts_val.machine[0] = 'i';
strcpy(uts_val.machine + 1, itoa(getprocessor()));
#endif
if(f > 0) printf("PM: failed to register %d processes with DS.\n", f);
system_hz = sys_hz();
/* Map out our own text and data. This is normally done in crtso.o
* but PM is an exception - we don't get to talk to VM so early on.
* That's why we override munmap() and munmap_text() in utility.c.
*
* _minix_unmapzero() is the same code in crtso.o that normally does
* it on startup. It's best that it's there as crtso.o knows exactly
* what the ranges are of the filler data.
*/
unmap_ok = 1;
_minix_unmapzero();
}
/*===========================================================================*
* get_nice_value *
*===========================================================================*/
PRIVATE int get_nice_value(queue)
int queue; /* store mem chunks here */
{
/* Processes in the boot image have a priority assigned. The PM doesn't know
* about priorities, but uses 'nice' values instead. The priority is between
* MIN_USER_Q and MAX_USER_Q. We have to scale between PRIO_MIN and PRIO_MAX.
*/
int nice_val = (queue - USER_Q) * (PRIO_MAX-PRIO_MIN+1) /
(MIN_USER_Q-MAX_USER_Q+1);
if (nice_val > PRIO_MAX) nice_val = PRIO_MAX; /* shouldn't happen */
if (nice_val < PRIO_MIN) nice_val = PRIO_MIN; /* shouldn't happen */
return nice_val;
}
void checkme(char *str, int line)
{
struct mproc *trmp;
int boned = 0;
int proc_nr;
for (proc_nr=0, trmp=mproc; proc_nr < NR_PROCS; proc_nr++, trmp++) {
if ((trmp->mp_flags & (REPLY | IN_USE | EXITING)) ==
(REPLY | IN_USE)) {
int tp;
if(pm_isokendpt(trmp->mp_endpoint, &tp) != OK) {
printf("PM: %s:%d: reply %d to %s is bogus endpoint %d after call %d by %d\n",
str, line, trmp->mp_reply.m_type,
trmp->mp_name, trmp->mp_endpoint, call_nr, who_e);
boned=1;
}
}
if(boned) panic(__FILE__, "corrupt mp_endpoint?", NO_NUM);
}
}
/*===========================================================================*
* handle_fs_reply *
*===========================================================================*/
PRIVATE void handle_fs_reply()
{
struct mproc *rmp;
endpoint_t proc_e;
int r, proc_n;
/* PM_REBOOT is the only request not associated with a process.
* Handle its reply first.
*/
if (call_nr == PM_REBOOT_REPLY) {
vir_bytes code_addr;
size_t code_size;
/* Ask the kernel to abort. All system services, including
* the PM, will get a HARD_STOP notification. Await the
* notification in the main loop.
*/
code_addr = (vir_bytes) monitor_code;
code_size = strlen(monitor_code) + 1;
sys_abort(abort_flag, PM_PROC_NR, code_addr, code_size);
return;
}
/* Get the process associated with this call */
proc_e = m_in.PM_PROC;
if (pm_isokendpt(proc_e, &proc_n) != OK) {
panic(__FILE__, "handle_fs_reply: got bad endpoint from FS", proc_e);
}
rmp = &mproc[proc_n];
/* Now that FS replied, mark the process as FS-idle again */
if (!(rmp->mp_flags & FS_CALL))
panic(__FILE__, "handle_fs_reply: reply without request", call_nr);
rmp->mp_flags &= ~FS_CALL;
if (rmp->mp_flags & UNPAUSED)
panic(__FILE__, "handle_fs_reply: UNPAUSED set on entry", call_nr);
/* Call-specific handler code */
switch (call_nr) {
case PM_SETUID_REPLY:
case PM_SETGID_REPLY:
/* Wake up the original caller */
setreply(rmp-mproc, OK);
break;
case PM_SETSID_REPLY:
/* Wake up the original caller */
setreply(rmp-mproc, rmp->mp_procgrp);
break;
case PM_EXEC_REPLY:
exec_restart(rmp, m_in.PM_STATUS);
break;
case PM_EXIT_REPLY:
exit_restart(rmp, FALSE /*dump_core*/);
break;
case PM_CORE_REPLY:
if (m_in.PM_STATUS == OK)
rmp->mp_sigstatus |= DUMPED;
exit_restart(rmp, TRUE /*dump_core*/);
break;
case PM_FORK_REPLY:
/* Wake up the newly created process */
setreply(proc_n, OK);
/* Wake up the parent */
setreply(rmp->mp_parent, rmp->mp_pid);
break;
case PM_FORK_NB_REPLY:
/* Nothing to do */
break;
case PM_UNPAUSE_REPLY:
/* Process is now unpaused */
rmp->mp_flags |= UNPAUSED;
break;
default:
panic(__FILE__, "handle_fs_reply: unknown reply code", call_nr);
}
/* Now that the process is idle again, look at pending signals */
if ((rmp->mp_flags & (IN_USE | EXITING)) == IN_USE)
restart_sigs(rmp);
}
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