usr/src/cmd/mdb/common/kmdb/kmdb_context.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 /*
  30  * Debugger co-routine context support.  kmdb co-routines are essentially the
  31  * same as the ones used by mdb, with the exception that we allocate the stack
  32  * for the co-routine from our heap.
  33  */
  34
  35 #include <kmdb/kmdb_context_impl.h>
  36 #include <mdb/mdb_modapi.h>
  37 #include <mdb/mdb_debug.h>
  38 #include <mdb/mdb_err.h>
  39 #include <mdb/mdb_umem.h>
  40 #include <mdb/mdb.h>
  41
  42 #include <sys/types.h>
  43
  44 #include <ucontext.h>
  45 #include <setjmp.h>
  46
  47 static void
  48 context_init(mdb_context_t *volatile c)
  49 {
  50         c->ctx_status = c->ctx_func();
  51         ASSERT(c->ctx_resumes > 0);
  52         longjmp(c->ctx_pcb, 1);
  53 }
  54
  55 mdb_context_t *
  56 mdb_context_create(int (*func)(void))
  57 {
  58         mdb_context_t *c = mdb_zalloc(sizeof (mdb_context_t), UM_NOSLEEP);
  59         size_t pagesize = mdb.m_pagesize;
  60
  61         if (c == NULL)
  62                 return (NULL);
  63
  64         c->ctx_func = func;
  65         c->ctx_stacksize = pagesize * 4;
  66         c->ctx_stack = mdb_alloc_align(c->ctx_stacksize, pagesize, UM_NOSLEEP);
  67
  68         if (c->ctx_stack == NULL) {
  69                 mdb_free(c, sizeof (mdb_context_t));
  70                 return (NULL);
  71         }
  72
  73         kmdb_makecontext(&c->ctx_uc, (void (*)(void *))context_init, c,
  74             c->ctx_stack, c->ctx_stacksize);
  75
  76         return (c);
  77 }
  78
  79 void
  80 mdb_context_destroy(mdb_context_t *c)
  81 {
  82         mdb_free_align(c->ctx_stack, c->ctx_stacksize);
  83         mdb_free(c, sizeof (mdb_context_t));
  84 }
  85
  86 void
  87 mdb_context_switch(mdb_context_t *c)
  88 {
  89         if (setjmp(c->ctx_pcb) == 0 && kmdb_setcontext(&c->ctx_uc) == -1)
  90                 fail("failed to change context to %p", (void *)c);
  91         else
  92                 fail("unexpectedly returned from context %p", (void *)c);
  93 }
  94
  95 jmp_buf *
  96 mdb_context_getpcb(mdb_context_t *c)
  97 {
  98         c->ctx_resumes++;
  99         return (&c->ctx_pcb);
 100 }