1335d5d700
instance numbers, encoded and decoded using macros in <minix/endpoint.h>.
proc number -> endpoint migration
. proc_nr in the interrupt hook is now an endpoint, proc_nr_e.
. m_source for messages and notifies is now an endpoint, instead of
proc number.
. isokendpt() converts an endpoint to a process number, returns
success (but fails if the process number is out of range, the
process slot is not a living process, or the given endpoint
number does not match the endpoint number in the process slot,
indicating an old process).
. okendpt() is the same as isokendpt(), but panic()s if the conversion
fails. This is mainly used for decoding message.m_source endpoints,
and other endpoint numbers in kernel data structures, which should
always be correct.
. if DEBUG_ENABLE_IPC_WARNINGS is enabled, isokendpt() and okendpt()
get passed the __FILE__ and __LINE__ of the calling lines, and
print messages about what is wrong with the endpoint number
(out of range proc, empty proc, or inconsistent endpoint number),
with the caller, making finding where the conversion failed easy
without having to include code for every call to print where things
went wrong. Sometimes this is harmless (wrong arg to a kernel call),
sometimes it's a fatal internal inconsistency (bogus m_source).
. some process table fields have been appended an _e to indicate it's
become and endpoint.
. process endpoint is stored in p_endpoint, without generation number.
it turns out the kernel never needs the generation number, except
when fork()ing, so it's decoded then.
. kernel calls all take endpoints as arguments, not proc numbers.
the one exception is sys_fork(), which needs to know in which slot
to put the child.
87 lines
2.8 KiB
C
87 lines
2.8 KiB
C
/* The kernel call implemented in this file:
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* m_type: SYS_FORK
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*
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* The parameters for this kernel call are:
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* m1_i1: PR_SLOT (child's process table slot)
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* m1_i2: PR_ENDPT (parent, process that forked)
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*/
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#include "../system.h"
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#include <signal.h>
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#if (CHIP == INTEL)
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#include "../protect.h"
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#endif
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#include <minix/endpoint.h>
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#if USE_FORK
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/*===========================================================================*
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* do_fork *
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*===========================================================================*/
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PUBLIC int do_fork(m_ptr)
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register message *m_ptr; /* pointer to request message */
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{
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/* Handle sys_fork(). PR_ENDPT has forked. The child is PR_SLOT. */
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#if (CHIP == INTEL)
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reg_t old_ldt_sel;
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#endif
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register struct proc *rpc; /* child process pointer */
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struct proc *rpp; /* parent process pointer */
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int i, gen;
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int p_proc;
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if(!isokendpt(m_ptr->PR_ENDPT, &p_proc))
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return EINVAL;
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rpp = proc_addr(p_proc);
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rpc = proc_addr(m_ptr->PR_SLOT);
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if (isemptyp(rpp) || ! isemptyp(rpc)) return(EINVAL);
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/* Copy parent 'proc' struct to child. And reinitialize some fields. */
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gen = _ENDPOINT_G(rpc->p_endpoint);
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#if (CHIP == INTEL)
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old_ldt_sel = rpc->p_ldt_sel; /* backup local descriptors */
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*rpc = *rpp; /* copy 'proc' struct */
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rpc->p_ldt_sel = old_ldt_sel; /* restore descriptors */
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#else
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*rpc = *rpp; /* copy 'proc' struct */
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#endif
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if(++gen >= _ENDPOINT_MAX_GENERATION) /* increase generation */
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gen = 1; /* generation number wraparound */
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rpc->p_nr = m_ptr->PR_SLOT; /* this was obliterated by copy */
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rpc->p_endpoint = _ENDPOINT(gen, rpc->p_nr); /* new endpoint of slot */
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/* Only one in group should have SIGNALED, child doesn't inherit tracing. */
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rpc->p_rts_flags |= NO_MAP; /* inhibit process from running */
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rpc->p_rts_flags &= ~(SIGNALED | SIG_PENDING | P_STOP);
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sigemptyset(&rpc->p_pending);
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rpc->p_reg.retreg = 0; /* child sees pid = 0 to know it is child */
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rpc->p_user_time = 0; /* set all the accounting times to 0 */
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rpc->p_sys_time = 0;
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/* Parent and child have to share the quantum that the forked process had,
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* so that queued processes do not have to wait longer because of the fork.
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* If the time left is odd, the child gets an extra tick.
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*/
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rpc->p_ticks_left = (rpc->p_ticks_left + 1) / 2;
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rpp->p_ticks_left = rpp->p_ticks_left / 2;
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/* If the parent is a privileged process, take away the privileges from the
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* child process and inhibit it from running by setting the NO_PRIV flag.
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* The caller should explicitely set the new privileges before executing.
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*/
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if (priv(rpp)->s_flags & SYS_PROC) {
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rpc->p_priv = priv_addr(USER_PRIV_ID);
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rpc->p_rts_flags |= NO_PRIV;
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}
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/* Calculate endpoint identifier, so caller knows what it is. */
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m_ptr->PR_ENDPT = rpc->p_endpoint;
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return(OK);
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}
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#endif /* USE_FORK */
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