xref: /openbsd-src/sys/dev/ksyms.c (revision d13be5d47e4149db2549a9828e244d59dbc43f15)
1 /*	$OpenBSD: ksyms.c,v 1.21 2011/06/23 16:02:33 tedu Exp $	*/
2 /*
3  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
4  * Copyright (c) 2001 Artur Grabowski <art@openbsd.org>
5  * All rights reserved.
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  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
17  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
18  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
19  * THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  */
27 
28 #include <sys/param.h>
29 #include <sys/buf.h>
30 #include <sys/exec.h>
31 #include <sys/systm.h>
32 #include <sys/uio.h>
33 #include <sys/malloc.h>
34 #include <sys/fcntl.h>
35 #include <sys/conf.h>
36 
37 #include <uvm/uvm_extern.h>
38 
39 #ifdef _NLIST_DO_ELF
40 #include <sys/exec_elf.h>
41 #endif
42 
43 #include <machine/cpu.h>
44 
45 extern char *esym;				/* end of symbol table */
46 #if defined(__sparc64__) || defined(__mips__)
47 extern char *ssym;				/* end of kernel */
48 #else
49 extern long end;				/* end of kernel */
50 #endif
51 
52 static caddr_t ksym_head;
53 static caddr_t ksym_syms;
54 static size_t ksym_head_size;
55 static size_t ksym_syms_size;
56 
57 void	ksymsattach(int);
58 
59 /*
60  * We assume __LDPGSZ is a multiple of PAGE_SIZE (it is)
61  */
62 
63 /*ARGSUSED*/
64 void
65 ksymsattach(int num)
66 {
67 
68 #if defined(__sparc64__) || defined(__mips__)
69 	if (esym <= ssym) {
70 		printf("/dev/ksyms: Symbol table not valid.\n");
71 		return;
72 	}
73 #else
74 	if (esym <= (char *)&end) {
75 		printf("/dev/ksyms: Symbol table not valid.\n");
76 		return;
77 	}
78 #endif
79 
80 #ifdef _NLIST_DO_ELF
81 	do {
82 #if defined(__sparc64__) || defined(__mips__)
83 		caddr_t symtab = ssym;
84 #else
85 		caddr_t symtab = (caddr_t)&end;
86 #endif
87 		Elf_Ehdr *elf;
88 		Elf_Shdr *shdr;
89 		int i;
90 
91 		elf = (Elf_Ehdr *)symtab;
92 		if (memcmp(elf->e_ident, ELFMAG, SELFMAG) != 0 ||
93 		    elf->e_ident[EI_CLASS] != ELFCLASS ||
94 		    elf->e_machine != ELF_TARG_MACH)
95 			break;
96 
97 		shdr = (Elf_Shdr *)&symtab[elf->e_shoff];
98 		for (i = 0; i < elf->e_shnum; i++) {
99 			if (shdr[i].sh_type == SHT_SYMTAB) {
100 				break;
101 			}
102 		}
103 
104 		/*
105 		 * No symbol table found.
106 		 */
107 		if (i == elf->e_shnum)
108 			break;
109 
110 		/*
111 		 * No additional header.
112 		 */
113 		ksym_head_size = 0;
114 		ksym_syms = symtab;
115 		ksym_syms_size = (size_t)(esym - symtab);
116 
117 		return;
118 	} while (0);
119 #endif
120 
121 #ifdef _NLIST_DO_AOUT
122 	{
123 		/*
124 		 * a.out header.
125 		 * Fake up a struct exec.
126 		 * We only fill in the following non-zero entries:
127 		 *	a_text - fake text segment (struct exec only)
128 		 *	a_syms - size of symbol table
129 		 */
130 		caddr_t symtab = (char *)(&end + 1);
131 		struct exec *k1;
132 
133 		ksym_head_size = __LDPGSZ;
134 		ksym_head = malloc(ksym_head_size, M_DEVBUF, M_NOWAIT | M_ZERO);
135 		if (ksym_head == NULL) {
136 			printf("failed to allocate memory for /dev/ksyms\n");
137 			return;
138 		}
139 
140 		k1 = (struct exec *)ksym_head;
141 
142 		N_SETMAGIC(*k1, ZMAGIC, MID_MACHINE, 0);
143 		k1->a_text = __LDPGSZ;
144 		k1->a_syms = end;
145 
146 		ksym_syms = symtab;
147 		ksym_syms_size = (size_t)(esym - symtab);
148 	}
149 #endif
150 }
151 
152 /*ARGSUSED*/
153 int
154 ksymsopen(dev_t dev, int flag, int mode, struct proc *p)
155 {
156 
157 	/* There are no non-zero minor devices */
158 	if (minor(dev) != 0)
159 		return (ENXIO);
160 
161 	/* This device is read-only */
162 	if ((flag & FWRITE))
163 		return (EPERM);
164 
165 	/* ksym_syms must be initialized */
166 	if (ksym_syms == NULL)
167 		return (ENXIO);
168 
169 	return (0);
170 }
171 
172 /*ARGSUSED*/
173 int
174 ksymsclose(dev_t dev, int flag, int mode, struct proc *p)
175 {
176 
177 	return (0);
178 }
179 
180 /*ARGSUSED*/
181 int
182 ksymsread(dev_t dev, struct uio *uio, int flags)
183 {
184 	int error;
185 	size_t len;
186 	caddr_t v;
187 	size_t off;
188 
189 	while (uio->uio_resid > 0) {
190 		if (uio->uio_offset >= ksym_head_size + ksym_syms_size)
191 			break;
192 
193 		if (uio->uio_offset < ksym_head_size) {
194 			v = ksym_head + uio->uio_offset;
195 			len = ksym_head_size - uio->uio_offset;
196 		} else {
197 			off = uio->uio_offset - ksym_head_size;
198 			v = ksym_syms + off;
199 			len = ksym_syms_size - off;
200 		}
201 
202 		if (len > uio->uio_resid)
203 			len = uio->uio_resid;
204 
205 		if ((error = uiomove(v, len, uio)) != 0)
206 			return (error);
207 	}
208 
209 	return (0);
210 }
211