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      1 /*	$NetBSD: subr_spldebug.c,v 1.3 2010/04/25 11:49:22 ad Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2009, 2010 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by David Young.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 /*
     33  * Interrupt priority level debugging code.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 __KERNEL_RCSID(0, "$NetBSD: subr_spldebug.c,v 1.3 2010/04/25 11:49:22 ad Exp $");
     38 
     39 #include <sys/param.h>
     40 #include <sys/spldebug.h>
     41 #include <sys/systm.h>
     42 #include <sys/kernel.h>
     43 #include <sys/cpu.h>
     44 #include <machine/return.h>
     45 
     46 #define SPLRAISE_STACKLEN 32
     47 
     48 void *splraise_retaddrs[MAXCPUS][SPLRAISE_STACKLEN][4];
     49 int splraise_depth[MAXCPUS] = {0};
     50 int spllowered_to[MAXCPUS] = {0};
     51 void *spllowered_from[MAXCPUS][2] = {{0}};
     52 bool spldebug = false;
     53 
     54 void	spldebug_start(void);
     55 void	spldebug_stop(void);
     56 
     57 void
     58 spldebug_start(void)
     59 {
     60 	spldebug = true;
     61 }
     62 
     63 void
     64 spldebug_stop(void)
     65 {
     66 	spldebug = false;
     67 }
     68 
     69 void
     70 spldebug_lower(int ipl)
     71 {
     72 	u_int cidx;
     73 
     74 	if (!spldebug)
     75 		return;
     76 
     77 	if (ipl == IPL_HIGH)
     78 		return;
     79 
     80 	cidx = cpu_index(curcpu());
     81 
     82 	KASSERT(cidx < maxcpus);
     83 
     84 	splraise_depth[cidx] = 0;
     85 	spllowered_to[cidx] = ipl;
     86 #if 0
     87 	spllowered_from[cidx][0] = return_address(0);
     88 	spllowered_from[cidx][1] = return_address(1);
     89 #endif
     90 }
     91 
     92 void
     93 spldebug_raise(int ipl)
     94 {
     95 	int i;
     96 	u_int cidx;
     97 	void **retaddrs;
     98 
     99 	if (!spldebug)
    100 		return;
    101 
    102 	if (ipl != IPL_HIGH)
    103 		return;
    104 
    105 	cidx = cpu_index(curcpu());
    106 
    107 	KASSERT(cidx < maxcpus);
    108 
    109 	if (splraise_depth[cidx] >= SPLRAISE_STACKLEN)
    110 		return;
    111 
    112 	retaddrs = &splraise_retaddrs[cidx][splraise_depth[cidx]++][0];
    113 
    114 	retaddrs[0] = retaddrs[1] = retaddrs[2] = retaddrs[3] = NULL;
    115 
    116 	for (i = 0; i < 4; i++) {
    117 		retaddrs[i] = return_address(i);
    118 
    119 		if (retaddrs[i] == NULL)
    120 			break;
    121 	}
    122 }
    123