cca24d06d8
kernel (sys task). The main reason is that these would have to become cpu local variables on SMP. Once the system task is not a task but a genuine part of the kernel there is even less reason to have these extra variables as proc_ptr will already contain all neccessary information. In addition converting who_e to the process pointer and back again all the time will be avoided. Although proc_ptr will contain all important information, accessing it as a cpu local variable will be fairly expensive, hence the value would be assigned to some on stack local variable. Therefore it is better to add the 'caller' argument to the syscall handlers to pass the value on stack anyway. It also clearly denotes on who's behalf is the syscall being executed. This patch also ANSIfies the syscall function headers. Last but not least, it also fixes a potential bug in virtual_copy_f() in case the check is disabled. So far the function in case of a failure could possible reuse an old who_p in case this function had not been called from the system task. virtual_copy_f() takes the caller as a parameter too. In case the checking is disabled, the caller must be NULL and non NULL if it is enabled as we must be able to suspend the caller.
114 lines
4 KiB
C
114 lines
4 KiB
C
/* The kernel call implemented in this file:
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* m_type: SYS_VTIMER
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*
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* The parameters for this kernel call are:
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* m2_i1: VT_WHICH (the timer: VT_VIRTUAL or VT_PROF)
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* m2_i2: VT_SET (whether to set, or just retrieve)
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* m2_l1: VT_VALUE (new/old expiration time, in ticks)
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* m2_l2: VT_ENDPT (process to which the timer belongs)
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*/
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#include "../system.h"
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#include <signal.h>
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#include <minix/endpoint.h>
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#if USE_VTIMER
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/*===========================================================================*
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* do_vtimer *
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*===========================================================================*/
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PUBLIC int do_vtimer(struct proc * caller, message * m_ptr)
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{
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/* Set and/or retrieve the value of one of a process' virtual timers. */
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struct proc *rp; /* pointer to process the timer belongs to */
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register int pt_flag; /* the misc on/off flag for the req.d timer */
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register clock_t *pt_left; /* pointer to the process' ticks-left field */
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clock_t old_value; /* the previous number of ticks left */
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int proc_nr, proc_nr_e;
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/* The requesting process must be privileged. */
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if (! (priv(caller)->s_flags & SYS_PROC)) return(EPERM);
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if (m_ptr->VT_WHICH != VT_VIRTUAL && m_ptr->VT_WHICH != VT_PROF)
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return(EINVAL);
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/* The target process must be valid. */
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proc_nr_e = (m_ptr->VT_ENDPT == SELF) ? m_ptr->m_source : m_ptr->VT_ENDPT;
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if (!isokendpt(proc_nr_e, &proc_nr)) return(EINVAL);
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rp = proc_addr(proc_nr);
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/* Determine which flag and which field in the proc structure we want to
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* retrieve and/or modify. This saves us having to differentiate between
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* VT_VIRTUAL and VT_PROF multiple times below.
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*/
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if (m_ptr->VT_WHICH == VT_VIRTUAL) {
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pt_flag = MF_VIRT_TIMER;
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pt_left = &rp->p_virt_left;
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} else { /* VT_PROF */
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pt_flag = MF_PROF_TIMER;
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pt_left = &rp->p_prof_left;
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}
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/* Retrieve the old value. */
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if (rp->p_misc_flags & pt_flag) {
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old_value = *pt_left;
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if (old_value < 0) old_value = 0;
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} else {
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old_value = 0;
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}
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/* Set the new value, if requested. This is called from the system task, so
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* we can be interrupted by the clock interrupt, but not by the clock task.
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* Therefore we only have to protect against interference from clock.c's
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* clock_handler(). We can do this without disabling interrupts, by removing
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* the timer's flag before changing the ticks-left field; in that case the
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* clock interrupt will not touch the latter anymore.
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*/
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if (m_ptr->VT_SET) {
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rp->p_misc_flags &= ~pt_flag; /* disable virtual timer */
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if (m_ptr->VT_VALUE > 0) {
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*pt_left = m_ptr->VT_VALUE; /* set new timer value */
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rp->p_misc_flags |= pt_flag; /* (re)enable virtual timer */
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} else {
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*pt_left = 0; /* clear timer value */
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}
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}
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m_ptr->VT_VALUE = old_value;
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return(OK);
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}
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#endif /* USE_VTIMER */
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/*===========================================================================*
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* vtimer_check *
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*===========================================================================*/
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PUBLIC void vtimer_check(rp)
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struct proc *rp; /* pointer to the process */
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{
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/* This is called from the clock task, so we can be interrupted by the clock
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* interrupt, but not by the system task. Therefore we only have to protect
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* against interference from the clock handler. We can safely perform the
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* following actions without locking as well though, as the clock handler
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* never alters p_misc_flags, and only decreases p_virt_left/p_prof_left.
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*/
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/* Check if the virtual timer expired. If so, send a SIGVTALRM signal. */
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if ((rp->p_misc_flags & MF_VIRT_TIMER) && rp->p_virt_left <= 0) {
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rp->p_misc_flags &= ~MF_VIRT_TIMER;
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rp->p_virt_left = 0;
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cause_sig(rp->p_nr, SIGVTALRM);
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}
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/* Check if the profile timer expired. If so, send a SIGPROF signal. */
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if ((rp->p_misc_flags & MF_PROF_TIMER) && rp->p_prof_left <= 0) {
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rp->p_misc_flags &= ~MF_PROF_TIMER;
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rp->p_prof_left = 0;
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cause_sig(rp->p_nr, SIGPROF);
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}
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}
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