minix/lib/libsys/sef_signal.c
Cristiano Giuffrida cb176df60f New RS and new signal handling for system processes.
UPDATING INFO:
20100317:
        /usr/src/etc/system.conf updated to ignore default kernel calls: copy
        it (or merge it) to /etc/system.conf.
        The hello driver (/dev/hello) added to the distribution:
        # cd /usr/src/commands/scripts && make clean install
        # cd /dev && MAKEDEV hello

KERNEL CHANGES:
- Generic signal handling support. The kernel no longer assumes PM as a signal
manager for every process. The signal manager of a given process can now be
specified in its privilege slot. When a signal has to be delivered, the kernel
performs the lookup and forwards the signal to the appropriate signal manager.
PM is the default signal manager for user processes, RS is the default signal
manager for system processes. To enable ptrace()ing for system processes, it
is sufficient to change the default signal manager to PM. This will temporarily
disable crash recovery, though.
- sys_exit() is now split into sys_exit() (i.e. exit() for system processes,
which generates a self-termination signal), and sys_clear() (i.e. used by PM
to ask the kernel to clear a process slot when a process exits).
- Added a new kernel call (i.e. sys_update()) to swap two process slots and
implement live update.

PM CHANGES:
- Posix signal handling is no longer allowed for system processes. System
signals are split into two fixed categories: termination and non-termination
signals. When a non-termination signaled is processed, PM transforms the signal
into an IPC message and delivers the message to the system process. When a
termination signal is processed, PM terminates the process.
- PM no longer assumes itself as the signal manager for system processes. It now
makes sure that every system signal goes through the kernel before being
actually processes. The kernel will then dispatch the signal to the appropriate
signal manager which may or may not be PM.

SYSLIB CHANGES:
- Simplified SEF init and LU callbacks.
- Added additional predefined SEF callbacks to debug crash recovery and
live update.
- Fixed a temporary ack in the SEF init protocol. SEF init reply is now
completely synchronous.
- Added SEF signal event type to provide a uniform interface for system
processes to deal with signals. A sef_cb_signal_handler() callback is
available for system processes to handle every received signal. A
sef_cb_signal_manager() callback is used by signal managers to process
system signals on behalf of the kernel.
- Fixed a few bugs with memory mapping and DS.

VM CHANGES:
- Page faults and memory requests coming from the kernel are now implemented
using signals.
- Added a new VM call to swap two process slots and implement live update.
- The call is used by RS at update time and in turn invokes the kernel call
sys_update().

RS CHANGES:
- RS has been reworked with a better functional decomposition.
- Better kernel call masks. com.h now defines the set of very basic kernel calls
every system service is allowed to use. This makes system.conf simpler and
easier to maintain. In addition, this guarantees a higher level of isolation
for system libraries that use one or more kernel calls internally (e.g. printf).
- RS is the default signal manager for system processes. By default, RS
intercepts every signal delivered to every system process. This makes crash
recovery possible before bringing PM and friends in the loop.
- RS now supports fast rollback when something goes wrong while initializing
the new version during a live update.
- Live update is now implemented by keeping the two versions side-by-side and
swapping the process slots when the old version is ready to update.
- Crash recovery is now implemented by keeping the two versions side-by-side
and cleaning up the old version only when the recovery process is complete.

DS CHANGES:
- Fixed a bug when the process doing ds_publish() or ds_delete() is not known
by DS.
- Fixed the completely broken support for strings. String publishing is now
implemented in the system library and simply wraps publishing of memory ranges.
Ideally, we should adopt a similar approach for other data types as well.
- Test suite fixed.

DRIVER CHANGES:
- The hello driver has been added to the Minix distribution to demonstrate basic
live update and crash recovery functionalities.
- Other drivers have been adapted to conform the new SEF interface.
2010-03-17 01:15:29 +00:00

196 lines
6.4 KiB
C

#include "syslib.h"
#include <assert.h>
#include <signal.h>
#include <minix/sysutil.h>
/* SEF Signal callbacks. */
PRIVATE struct sef_cbs {
sef_cb_signal_handler_t sef_cb_signal_handler;
sef_cb_signal_manager_t sef_cb_signal_manager;
} sef_cbs = {
SEF_CB_SIGNAL_HANDLER_DEFAULT,
SEF_CB_SIGNAL_MANAGER_DEFAULT
};
/* SEF Signal prototypes for sef_receive(). */
PUBLIC _PROTOTYPE( int do_sef_signal_request, (message *m_ptr) );
/* Debug. */
EXTERN _PROTOTYPE( char* sef_debug_header, (void) );
/* Information about SELF. */
EXTERN endpoint_t sef_self_endpoint;
/*===========================================================================*
* process_sigmgr_signals *
*===========================================================================*/
PRIVATE void process_sigmgr_signals(void)
{
/* A signal manager has pending signals in the kernel. Process them. */
endpoint_t target;
sigset_t sigset;
int signo, r;
while (TRUE) {
/* Get an arbitrary pending signal. */
if((r=sys_getksig(&target, &sigset)) != OK)
panic("SEF", "sys_getksig failed", r);
if (target == NONE) {
/* Stop if there are no more pending signals. */
break;
} else {
/* Process every signal in the signal set. */
r = OK;
for(signo = 1; signo < _NSIG; signo++) {
if(sigismember(&sigset, signo)) {
/* Let the callback code process the signal. */
r = sef_cbs.sef_cb_signal_manager(target, signo);
/* Stop if process is gone. */
if(r == EDEADSRCDST) {
break;
}
}
}
/* Tell the kernel we are done if the target is still alive. */
if(r == OK) {
if((r=sys_endksig(target)) != OK)
panic("SEF","sys_endksig failed", r);
}
}
}
}
/*===========================================================================*
* process_sigmgr_self_signals *
*===========================================================================*/
PRIVATE void process_sigmgr_self_signals(sigset_t sigset)
{
/* A signal manager has pending signals for itself. Process them. */
int signo;
for(signo = 1; signo < _NSIG; signo++) {
if(sigismember(&sigset, signo)) {
/* Let the callback code process the signal. */
sef_cbs.sef_cb_signal_handler(signo);
}
}
}
/*===========================================================================*
* do_sef_signal_request *
*===========================================================================*/
PUBLIC int do_sef_signal_request(message *m_ptr)
{
/* Handle a SEF Signal request. */
int signo;
sigset_t sigset;
if(m_ptr->m_source == SYSTEM) {
/* Handle kernel signals. */
sigset = m_ptr->NOTIFY_ARG;
for (signo = SIGK_FIRST; signo <= SIGK_LAST; signo++) {
if (sigismember(&sigset, signo)) {
/* Let the callback code handle the kernel signal. */
sef_cbs.sef_cb_signal_handler(signo);
/* Handle SIGKSIG for a signal manager. */
if(signo == SIGKSIG) {
process_sigmgr_signals();
}
/* Handle SIGKSIGSM for a signal manager. */
else if(signo == SIGKSIGSM) {
process_sigmgr_self_signals(sigset);
}
}
}
}
else {
/* Handle system signals from a signal manager. */
signo = m_ptr->SIGS_SIG_NUM;
/* Debug. */
#if SEF_SIGNAL_DEBUG
sef_signal_debug_begin();
sef_signal_dprint("%s. Got a SEF Signal request for signal %d! About to handle signal.\n",
sef_debug_header(), signo);
sef_signal_debug_end();
#endif
/* Let the callback code handle the signal. */
sef_cbs.sef_cb_signal_handler(signo);
}
/* Return OK not to let anybody else intercept the request. */
return OK;
}
/*===========================================================================*
* sef_setcb_signal_handler *
*===========================================================================*/
PUBLIC void sef_setcb_signal_handler(sef_cb_signal_handler_t cb)
{
assert(cb != NULL);
sef_cbs.sef_cb_signal_handler = cb;
}
/*===========================================================================*
* sef_setcb_signal_manager *
*===========================================================================*/
PUBLIC void sef_setcb_signal_manager(sef_cb_signal_manager_t cb)
{
assert(cb != NULL);
sef_cbs.sef_cb_signal_manager = cb;
}
/*===========================================================================*
* sef_cb_signal_handler_null *
*===========================================================================*/
PUBLIC void sef_cb_signal_handler_null(int signo)
{
}
/*===========================================================================*
* sef_cb_signal_manager_null *
*===========================================================================*/
PUBLIC int sef_cb_signal_manager_null(endpoint_t target, int signo)
{
return OK;
}
/*===========================================================================*
* sef_cb_signal_handler_term *
*===========================================================================*/
PUBLIC void sef_cb_signal_handler_term(int signo)
{
/* Terminate in case of SIGTERM, ignore other signals. */
if(signo == SIGTERM) {
sef_exit(1);
}
}
/*===========================================================================*
* sef_cb_signal_handler_posix_default *
*===========================================================================*/
PUBLIC void sef_cb_signal_handler_posix_default(int signo)
{
switch(signo) {
/* Ignore when possible. */
case SIGCHLD:
case SIGWINCH:
case SIGCONT:
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
break;
/* Terminate in any other case unless it is a kernel signal. */
default:
if(!IS_SIGK(signo)) {
sef_exit(1);
}
break;
}
}