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      1 /*	$NetBSD: db_access.c,v 1.28 2026/02/25 05:34:42 skrll Exp $	*/
      2 
      3 /*
      4  * Mach Operating System
      5  * Copyright (c) 1991,1990 Carnegie Mellon University
      6  * All Rights Reserved.
      7  *
      8  * Permission to use, copy, modify and distribute this software and its
      9  * documentation is hereby granted, provided that both the copyright
     10  * notice and this permission notice appear in all copies of the
     11  * software, derivative works or modified versions, and any portions
     12  * thereof, and that both notices appear in supporting documentation.
     13  *
     14  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     15  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
     16  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     17  *
     18  * Carnegie Mellon requests users of this software to return to
     19  *
     20  *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
     21  *  School of Computer Science
     22  *  Carnegie Mellon University
     23  *  Pittsburgh PA 15213-3890
     24  *
     25  * any improvements or extensions that they make and grant Carnegie the
     26  * rights to redistribute these changes.
     27  *
     28  *	Author: David B. Golub, Carnegie Mellon University
     29  *	Date:	7/90
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: db_access.c,v 1.28 2026/02/25 05:34:42 skrll Exp $");
     34 
     35 #if defined(_KERNEL_OPT)
     36 #include "opt_kgdb.h"
     37 #endif
     38 
     39 #include <sys/param.h>
     40 #include <sys/proc.h>
     41 #include <sys/endian.h>
     42 
     43 #include <ddb/ddb.h>
     44 
     45 /*
     46  * Access unaligned data items on aligned (longword)
     47  * boundaries.
     48  *
     49  * This file is shared by ddb, kgdb and crash(8).
     50  */
     51 
     52 #if defined(DDB) || !defined(DDB) && !defined(KGDB)
     53 #define	_COMPILE_THIS
     54 #endif
     55 
     56 #if defined(_COMPILE_THIS) || defined(KGDB) && defined(SOFTWARE_SSTEP)
     57 
     58 db_expr_t
     59 db_get_value(db_addr_t addr, size_t size, bool is_signed)
     60 {
     61 	char data[sizeof(db_expr_t)] __aligned(sizeof(db_expr_t));
     62 	uintmax_t uvalue;
     63 	db_expr_t value;
     64 	size_t i;
     65 
     66 	db_read_bytes(addr, size, data);
     67 
     68 	uvalue = 0;
     69 #if BYTE_ORDER == LITTLE_ENDIAN
     70 	for (i = size; i-- > 0;)
     71 #else /* BYTE_ORDER == BIG_ENDIAN */
     72 	for (i = 0; i < size; i++)
     73 #endif /* BYTE_ORDER */
     74 		uvalue = (uvalue << 8) + (data[i] & 0xFF);
     75 
     76 	value = (db_expr_t)uvalue;
     77 
     78 	if (size < sizeof(db_expr_t) && is_signed
     79 	    && (value & ((db_expr_t)1 << (8*size - 1)))) {
     80 		value |= (unsigned long)~(db_expr_t)0 << (8*size - 1);
     81 	}
     82 	return (value);
     83 }
     84 
     85 #if defined DDB || defined _KMEMUSER
     86 quad_t
     87 db_get_qvalue(db_addr_t addr, size_t size, bool is_signed)
     88 {
     89 	uint64_t data;
     90 
     91 	if (size < sizeof(uint64_t)) {
     92 		if (is_signed)
     93 			return db_get_value(addr, size, true);
     94 		return (uint32_t)db_get_value(addr, size, false);
     95 	}
     96 
     97 	if (size != sizeof(data)) {
     98 		db_error("unsupported size\n");
     99 		/*NOTREACHED*/
    100 	}
    101 
    102 	db_read_bytes(addr, sizeof(data), (char *)&data);
    103 	return data;
    104 }
    105 #endif
    106 
    107 void
    108 db_put_value(db_addr_t addr, size_t size, db_expr_t value)
    109 {
    110 	char data[sizeof(db_expr_t)] __aligned(sizeof(db_expr_t));
    111 	size_t i;
    112 
    113 #if BYTE_ORDER == LITTLE_ENDIAN
    114 	for (i = 0; i < size; i++)
    115 #else /* BYTE_ORDER == BIG_ENDIAN */
    116 	for (i = size; i-- > 0;)
    117 #endif /* BYTE_ORDER */
    118 	{
    119 		data[i] = value & 0xFF;
    120 		value >>= 8;
    121 	}
    122 
    123 	db_write_bytes(addr, size, data);
    124 }
    125 
    126 #endif	/* _COMPILE_THIS || KGDB && SOFTWARE_SSTEP */
    127 
    128 #ifdef	_COMPILE_THIS
    129 
    130 void *
    131 db_read_ptr(const char *name)
    132 {
    133 	db_expr_t val;
    134 	void *p;
    135 
    136 	if (!db_value_of_name(name, &val)) {
    137 		db_printf("db_read_ptr: cannot find `%s'\n", name);
    138 		db_error(NULL);
    139 		/* NOTREACHED */
    140 	}
    141 	db_read_bytes((db_addr_t)val, sizeof(p), (char *)&p);
    142 	return p;
    143 }
    144 
    145 int
    146 db_read_int(const char *name)
    147 {
    148 	db_expr_t val;
    149 	int p;
    150 
    151 	if (!db_value_of_name(name, &val)) {
    152 		db_printf("db_read_int: cannot find `%s'\n", name);
    153 		db_error(NULL);
    154 		/* NOTREACHED */
    155 	}
    156 	db_read_bytes((db_addr_t)val, sizeof(p), (char *)&p);
    157 	return p;
    158 }
    159 
    160 #endif	/* _COMPILE_THIS */
    161