sys/kern/kern_upcall.c

   1 /*
   2  * Copyright (c) 2003,2004,2006 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/kern/kern_upcall.c,v 1.11 2006/09/10 21:35:10 dillon Exp $
  35  */
  36
  37 /*
  38  * Implement upcall registration and dispatch.
  39  */
  40
  41 #include <sys/param.h>
  42 #include <sys/systm.h>
  43 #include <sys/kernel.h>
  44 #include <sys/proc.h>
  45 #include <sys/upcall.h>
  46 #include <sys/thread2.h>
  47 #include <sys/upcall.h>
  48 #include <sys/malloc.h>
  49 #include <sys/sysproto.h>
  50 #include <sys/lock.h>
  51 #include <sys/signalvar.h>
  52
  53 #include <vm/vm.h>
  54 #include <vm/vm_param.h>
  55 #include <vm/vm_kern.h>
  56 #include <vm/pmap.h>
  57 #include <vm/vm_map.h>
  58
  59 #include <machine/cpu.h>
  60
  61 MALLOC_DEFINE(M_UPCALL, "upcalls", "upcall registration structures");
  62
  63 #ifdef SMP
  64
  65 static void
  66 sigupcall_remote(void *arg)
  67 {
  68         struct lwp *lp = arg;
  69         if (lp == lwkt_preempted_proc())
  70                 sigupcall();
  71 }
  72
  73 #endif
  74
  75 /*
  76  * upc_register:
  77  *
  78  *      Register an upcall context wrapper and procedure.  Note that the
  79  *      upcall context is set globally for the process, not for each upcall.
  80  *
  81  * ARGS(struct upcall *upc, upcall_func_t ctx, upcall_func_t func, void *data)
  82  */
  83 int
  84 sys_upc_register(struct upc_register_args *uap)
  85 {
  86     struct lwp *lp = curthread->td_lwp;
  87     struct vmspace *vm = curproc->p_vmspace;
  88     struct vmupcall *vu;
  89
  90     if (vm->vm_upccount >= UPCALL_MAXCOUNT)
  91         return(EFBIG);
  92
  93     vu = kmalloc(sizeof(struct vmupcall), M_UPCALL, M_WAITOK|M_ZERO);
  94     vu->vu_ctx = uap->ctxfunc;
  95     vu->vu_func = uap->func;
  96     vu->vu_data = uap->data;
  97     vu->vu_lwp = lp;
  98     lp->lwp_upcall = uap->upc;
  99
 100     if (vm->vm_upcalls != NULL)
 101         vu->vu_id = vm->vm_upcalls->vu_id + 1;
 102     else
 103         vu->vu_id = UPC_RESERVED;
 104     vu->vu_next = vm->vm_upcalls;
 105     vm->vm_upcalls = vu;
 106     ++vm->vm_upccount;
 107     uap->sysmsg_result = vu->vu_id;
 108     return(0);
 109 }
 110
 111 /*
 112  * upc_control:
 113  *
 114  * ARGS(int cmd, int upcid, void *data)
 115  */
 116 int
 117 sys_upc_control(struct upc_control_args *uap)
 118 {
 119     struct lwp *lp = curthread->td_lwp;
 120     struct lwp *targlp;
 121     struct vmspace *vms = curproc->p_vmspace;
 122     struct vmupcall *vu;
 123     struct vmupcall *vu_send;
 124     struct vmupcall **vupp;
 125     int error;
 126
 127     switch(uap->cmd) {
 128     case UPC_CONTROL_DISPATCH:
 129         /*
 130          * Dispatch the specified upcall id or the next pending id if -1.
 131          * the upcall will be marked pending but an actual upcall will only
 132          * occur if userland is not in a critical section and the userland
 133          * pending bit is not set.
 134          *
 135          * You can dispatch an upcall associated with your process or another
 136          * process sharing the same VM space.
 137          */
 138         error = (uap->upcid == -1) ? 0 : ENOENT;
 139         for (vu = vms->vm_upcalls; vu; vu = vu->vu_next) {
 140             if (vu->vu_id == uap->upcid ||
 141                 (uap->upcid == -1 && vu->vu_pending >= (int)uap->data && vu->vu_lwp == lp)
 142             ) {
 143                 if (vu->vu_pending < (int)uap->data)
 144                     vu->vu_pending = (int)uap->data;
 145                 error = 0;
 146                 targlp = vu->vu_lwp;
 147                 targlp->lwp_proc->p_flag |= P_UPCALLPEND;       /* XXX lwp flags */
 148                 if (targlp->lwp_proc->p_flag & P_UPCALLWAIT)
 149                     wakeup(&targlp->lwp_upcall);
 150 #ifdef SMP
 151                 if (targlp->lwp_thread->td_gd != mycpu)
 152                     lwkt_send_ipiq(targlp->lwp_thread->td_gd, sigupcall_remote, targlp);
 153                 else
 154                     sigupcall();
 155 #else
 156                 sigupcall();
 157 #endif
 158                 break;
 159             }
 160         }
 161         break;
 162     case UPC_CONTROL_NEXT:
 163         /*
 164          * This is used by the context code to fetch the next pending upcall.
 165          * The context code has two choices:  (A) it can drop
 166          * upcall->crit_count and set upcall->pending then make this call
 167          * unconditionally or * (B) it can drop upcall->crit_count and then
 168          * test upcall->pending and only make this call if upcall->pending
 169          * is set.  If upcall->pending is clear the context code can pop
 170          * the upcall stack itself and return without entering into the kernel
 171          * again.  (B) is more efficient but leaves a small window of
 172          * opportunity where multiple upcalls can pushdown the stack.
 173          *
 174          * If another upcall is pending the crit_count will be bumped and
 175          * the function, data, and context pointers will be returned in
 176          * registers (C cannot call this routine).  If no more upcalls are
 177          * pending the pending bit will be cleared and the 'data' argument
 178          * is expected to be pointing at the upcall context which we will
 179          * then pop, returning to the original code that was interrupted
 180          * (NOT the context code).
 181          */
 182         vu_send = NULL;
 183         for (vu = vms->vm_upcalls; vu; vu = vu->vu_next) {
 184             if (vu->vu_lwp == lp && vu->vu_pending) {
 185                 if (vu_send)
 186                     break;
 187                 vu_send = vu;
 188             }
 189         }
 190         /*
 191          * vu_send may be NULL, indicating that no more upcalls are pending
 192          * for this cpu.  We set the userland pending bit based on whether
 193          * additional upcalls are pending or not.
 194          */
 195         error = fetchupcall(vu_send, vu != NULL, uap->data);
 196         break;
 197     case UPC_CONTROL_DELETE:
 198         /*
 199          * Delete the specified upcall id.  If the upcall id is -1, delete
 200          * all upcall id's associated with the current process.
 201          */
 202         error = (uap->upcid == -1) ? 0 : ENOENT;
 203         vupp = &vms->vm_upcalls;
 204         while ((vu = *vupp) != NULL) {
 205             if (vu->vu_id == uap->upcid ||
 206                 (uap->upcid == -1 && vu->vu_lwp == lp)
 207             ) {
 208                 *vupp = vu->vu_next;
 209                 error = 0;
 210                 kfree(vu, M_UPCALL);
 211             } else {
 212                 vupp = &vu->vu_next;
 213             }
 214         }
 215         break;
 216     case UPC_CONTROL_POLL:
 217     case UPC_CONTROL_POLLANDCLEAR:
 218     case UPC_CONTROL_WAIT:
 219         /*
 220          * If upcid is -1 poll for the first pending upcall and return the
 221          * id or 0 if no upcalls are pending.
 222          *
 223          * If upcid is a particular upcall then poll that upcall and return
 224          * its pending status (0 or 1).  For POLLANDCLEAR, also clear the
 225          * pending status.  The userland pending bit is not modified by
 226          * this call (maybe we should modify it for poll-and-clear).
 227          */
 228         error = (uap->upcid == -1) ? 0 : ENOENT;
 229         for (vu = vms->vm_upcalls; vu; vu = vu->vu_next) {
 230             if (vu->vu_id == uap->upcid ||
 231                 (uap->upcid == -1 && vu->vu_pending >= (int)uap->data && vu->vu_lwp == lp)
 232             ) {
 233                 error = 0;
 234                 if (uap->upcid == -1)
 235                     uap->sysmsg_result = vu->vu_id;
 236                 else
 237                     uap->sysmsg_result = vu->vu_pending;
 238                 if (uap->cmd == UPC_CONTROL_POLLANDCLEAR)
 239                     vu->vu_pending = 0;
 240                 break;
 241             }
 242         }
 243         if (uap->cmd == UPC_CONTROL_WAIT && vu == NULL) {
 244             lp->lwp_proc->p_flag |= P_UPCALLWAIT;       /* XXX lwp flags */
 245             tsleep(&lp->lwp_upcall, PCATCH, "wupcall", 0);
 246             lp->lwp_proc->p_flag &= ~P_UPCALLWAIT;      /* XXX lwp flags */
 247         }
 248         break;
 249     default:
 250         error = EINVAL;
 251         break;
 252     }
 253     return(error);
 254 }
 255
 256 void
 257 upc_release(struct vmspace *vm, struct lwp *lp)
 258 {
 259     struct vmupcall **vupp;
 260     struct vmupcall *vu;
 261
 262     vupp = &vm->vm_upcalls;
 263     while ((vu = *vupp) != NULL) {
 264         if (vu->vu_lwp == lp) {
 265             *vupp = vu->vu_next;
 266             kfree(vu, M_UPCALL);
 267             --vm->vm_upccount;
 268         } else {
 269             vupp = &vu->vu_next;
 270         }
 271     }
 272 }
 273
 274 /*
 275  * XXX eventually we should sort by vu_pending priority and dispatch
 276  * the highest priority upcall first.
 277  */
 278 void
 279 postupcall(struct lwp *lp)
 280 {
 281     struct vmspace *vm = lp->lwp_proc->p_vmspace;
 282     struct vmupcall *vu;
 283     struct vmupcall *vu_send = NULL;
 284
 285     for (vu = vm->vm_upcalls; vu; vu = vu->vu_next) {
 286         if (vu->vu_lwp == lp && vu->vu_pending) {
 287             if (vu_send) {
 288                 sendupcall(vu, 1);
 289                 return;
 290             }
 291             vu_send = vu;
 292         }
 293     }
 294     if (vu_send)
 295         sendupcall(vu_send, 0);
 296 }
 297