critical.c

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    1 /*-
    2  * Copyright (c) 2001 Matthew Dillon.  This code is distributed under
    3  * the BSD copyright, /usr/src/COPYRIGHT.
    4  *
    5  * $FreeBSD: releng/5.0/sys/i386/i386/critical.c 99742 2002-07-10 20:15:58Z dillon $
    6  */
    7 
    8 #include <sys/param.h>
    9 #include <sys/systm.h>
   10 #include <sys/signalvar.h>
   11 #include <sys/kernel.h>
   12 #include <sys/lock.h>
   13 #include <sys/mutex.h>
   14 #include <sys/pcpu.h>
   15 #include <sys/proc.h>
   16 #include <sys/sysctl.h>
   17 #include <sys/ucontext.h>
   18 #include <machine/critical.h>
   19 
   20 #ifdef SMP
   21 #include <machine/privatespace.h>
   22 #include <machine/smp.h>
   23 #else
   24 /*
   25  * XXX this mess to get sched_ithd() and call_fast_unpend()
   26  */
   27 #include <sys/bus.h>
   28 #include <machine/apic.h>
   29 #include <machine/frame.h>
   30 #include <i386/isa/icu.h>
   31 #include <i386/isa/intr_machdep.h>
   32 #endif
   33 
   34 void i386_unpend(void);         /* NOTE: not static, called from assembly */
   35 
   36 /*
   37  * cpu_unpend() -       called from critical_exit() inline after quick
   38  *                      interrupt-pending check.
   39  */
   40 void
   41 cpu_unpend(void)
   42 {
   43         register_t eflags;
   44         struct thread *td;
   45 
   46         td = curthread;
   47         eflags = intr_disable();
   48         if (PCPU_GET(int_pending)) {
   49                 ++td->td_intr_nesting_level;
   50                 i386_unpend();
   51                 --td->td_intr_nesting_level;
   52         }
   53         intr_restore(eflags);
   54 }
   55 
   56 /*
   57  * cpu_critical_fork_exit() - cleanup after fork
   58  *
   59  *      For i386 we do not have to do anything, td_critnest is
   60  *      handled by the fork trampoline code.
   61  */
   62 void
   63 cpu_critical_fork_exit(void)
   64 {
   65 }
   66 
   67 /*
   68  * cpu_thread_link() - thread linkup, initialize machine-dependant fields
   69  *
   70  *      There are currently no machine-dependant fields that require 
   71  *      initialization.
   72  */
   73 void
   74 cpu_thread_link(struct thread *td)
   75 {
   76 }
   77 
   78 /*
   79  * Called from cpu_unpend or called from the assembly vector code
   80  * to process any interrupts which may have occured while we were in
   81  * a critical section.
   82  *
   83  *      - interrupts must be disabled
   84  *      - td_critnest must be 0
   85  *      - td_intr_nesting_level must be incremented by the caller
   86  *
   87  * NOT STATIC (called from assembly)
   88  */
   89 void
   90 i386_unpend(void)
   91 {
   92         KASSERT(curthread->td_critnest == 0, ("unpend critnest != 0"));
   93         KASSERT((read_eflags() & PSL_I) == 0, ("unpend interrupts enabled1"));
   94         curthread->td_critnest = 1;
   95         for (;;) {
   96                 u_int32_t mask;
   97                 int irq;
   98 
   99                 /*
  100                  * Fast interrupts have priority
  101                  */
  102                 if ((mask = PCPU_GET(fpending)) != 0) {
  103                         irq = bsfl(mask);
  104                         PCPU_SET(fpending, mask & ~(1 << irq));
  105                         call_fast_unpend(irq);
  106                         KASSERT((read_eflags() & PSL_I) == 0,
  107                             ("unpend interrupts enabled2 %d", irq));
  108                         continue;
  109                 }
  110 
  111                 /*
  112                  * Threaded interrupts come next
  113                  */
  114                 if ((mask = PCPU_GET(ipending)) != 0) {
  115                         irq = bsfl(mask);
  116                         PCPU_SET(ipending, mask & ~(1 << irq));
  117                         sched_ithd((void *)irq);
  118                         KASSERT((read_eflags() & PSL_I) == 0,
  119                             ("unpend interrupts enabled3 %d", irq));
  120                         continue;
  121                 }
  122 
  123                 /*
  124                  * Software interrupts and delayed IPIs are last
  125                  *
  126                  * XXX give the bits #defined names.  see also
  127                  * isa/xxx_vector.s
  128                  */
  129                 if ((mask = PCPU_GET(spending)) != 0) {
  130                         irq = bsfl(mask);
  131                         PCPU_SET(spending, mask & ~(1 << irq));
  132                         switch(irq) {
  133                         case 0:         /* bit 0 - hardclock */
  134                                 mtx_lock_spin(&sched_lock);
  135                                 hardclock_process(curthread, 0);
  136                                 mtx_unlock_spin(&sched_lock);
  137                                 break;
  138                         case 1:         /* bit 1 - statclock */
  139                                 mtx_lock_spin(&sched_lock);
  140                                 statclock_process(curthread->td_kse,
  141                                     (register_t)i386_unpend, 0);
  142                                 mtx_unlock_spin(&sched_lock);
  143                                 break;
  144                         }
  145                         KASSERT((read_eflags() & PSL_I) == 0,
  146                             ("unpend interrupts enabled4 %d", irq));
  147                         continue;
  148                 }
  149                 break;
  150         }
  151         /*
  152          * Interrupts are still disabled, we can safely clear int_pending 
  153          * and td_critnest.
  154          */
  155         KASSERT((read_eflags() & PSL_I) == 0, ("unpend interrupts enabled5"));
  156         PCPU_SET(int_pending, 0);
  157         curthread->td_critnest = 0;
  158 }

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FreeBSD/Linux Kernel Cross Reference sys/i386/i386/critical.c

FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/critical.c