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 #include <sys/ksyms.h>
30 #include <sys/systm.h>
31 #include <sys/sysmacros.h>
32 #include <sys/debug.h>
33 #include <sys/cmn_err.h>
34 
35 static const char ksyms_shstrtab[] = "\0.symtab\0.strtab\0.shstrtab\0";
36 
37 #define	KSHDR_NULL	0
38 #define	KSHDR_SYMTAB	1
39 #define	KSHDR_STRTAB	2
40 #define	KSHDR_SHSTRTAB	3
41 #define	KSHDR_NUM	4
42 
43 typedef struct ksyms_header {
44 	Ehdr	elf_hdr;		/* Elf file header */
45 	Phdr	text_phdr;		/* text program header */
46 	Phdr	data_phdr;		/* data program header */
47 	Shdr	shdr[KSHDR_NUM];	/* section headers */
48 	char	shstrings[sizeof (ksyms_shstrtab)];	/* shstrtab strings */
49 } ksyms_header_t;
50 
51 #define	KW_HEADER	0x1
52 #define	KW_LOCALS	0x2
53 #define	KW_GLOBALS	0x4
54 #define	KW_STRINGS	0x8
55 
56 typedef struct ksyms_walkinfo {
57 	void	(*kw_emit)(const void *, void *, size_t);
58 	char	*kw_target;
59 	ssize_t	kw_resid;
60 	ssize_t kw_totalsize;
61 	int	kw_actions;
62 	size_t	kw_size[KW_STRINGS + 1];
63 } ksyms_walkinfo_t;
64 
65 krwlock_t ksyms_lock;
66 vmem_t *ksyms_arena;
67 
68 static void
ksyms_emit(ksyms_walkinfo_t * kwp,void * src,size_t size,int action)69 ksyms_emit(ksyms_walkinfo_t *kwp, void *src, size_t size, int action)
70 {
71 	if (kwp->kw_actions & action) {
72 		if ((kwp->kw_resid -= size) >= 0)
73 			kwp->kw_emit(src, kwp->kw_target, size);
74 		kwp->kw_totalsize += size;
75 	}
76 	kwp->kw_size[action] += size;
77 }
78 
79 /*ARGSUSED*/
80 static void
ksyms_walk_one(void * arg,void * base,size_t size)81 ksyms_walk_one(void *arg, void *base, size_t size)
82 {
83 	ksyms_walkinfo_t *kwp = arg;
84 	Shdr *symhdr = base;
85 	Shdr *strhdr = symhdr + symhdr->sh_link;
86 	size_t symsize = symhdr->sh_entsize;
87 	size_t nsyms = symhdr->sh_size / symsize;
88 	char *strings = (char *)strhdr->sh_addr;
89 	int i;
90 
91 	for (i = 1; i < nsyms; i++) {
92 		Sym *sym = (Sym *)(symhdr->sh_addr + i * symsize);
93 		Sym tmp = *sym;
94 		char *name = strings + sym->st_name;
95 		tmp.st_name = kwp->kw_size[KW_STRINGS];
96 		tmp.st_shndx = SHN_ABS;
97 		ksyms_emit(kwp, &tmp, sizeof (Sym),
98 		    ELF_ST_BIND(sym->st_info) == STB_LOCAL ?
99 		    KW_LOCALS : KW_GLOBALS);
100 		ksyms_emit(kwp, name, strlen(name) + 1, KW_STRINGS);
101 	}
102 }
103 
104 static ssize_t
ksyms_walk(ksyms_walkinfo_t * kwp,void * target,ssize_t resid,void (* emit)(const void *,void *,size_t),void * src,int actions)105 ksyms_walk(ksyms_walkinfo_t *kwp, void *target, ssize_t resid,
106 	void (*emit)(const void *, void *, size_t), void *src, int actions)
107 {
108 	Sym tmp;
109 
110 	bzero(kwp, sizeof (ksyms_walkinfo_t));
111 	kwp->kw_emit = emit;
112 	kwp->kw_target = target;
113 	kwp->kw_resid = resid;
114 	kwp->kw_actions = actions;
115 
116 	ksyms_emit(kwp, src, sizeof (ksyms_header_t), KW_HEADER);
117 	/*
118 	 * The first symbol table entry is all zeroes; it's unused
119 	 * because index 0 marks the end of symbol hash chains.
120 	 */
121 	bzero(&tmp, sizeof (Sym));
122 	ksyms_emit(kwp, &tmp, sizeof (Sym), KW_LOCALS);
123 	ksyms_emit(kwp, &tmp, 1, KW_STRINGS);
124 	vmem_walk(ksyms_arena, VMEM_ALLOC, ksyms_walk_one, kwp);
125 	return (kwp->kw_totalsize);
126 }
127 
128 size_t
ksyms_snapshot(void (* emit)(const void *,void *,size_t),void * buf,size_t len)129 ksyms_snapshot(void (*emit)(const void *, void *, size_t),
130 	void *buf, size_t len)
131 {
132 	ksyms_walkinfo_t kw;
133 	ksyms_header_t hdr;
134 	ssize_t size = 0, bufsize = len;
135 	Shdr *shp;
136 
137 	rw_enter(&ksyms_lock, RW_READER);
138 
139 	/*
140 	 * Compute the size of the header, locals, globals, and strings.
141 	 */
142 	(void) ksyms_walk(&kw, NULL, 0, NULL, NULL,
143 	    KW_HEADER | KW_LOCALS | KW_GLOBALS | KW_STRINGS);
144 
145 	/*
146 	 * Construct the ELF header.
147 	 */
148 	bzero(&hdr, sizeof (hdr));
149 
150 	hdr.elf_hdr = ((struct module *)modules.mod_mp)->hdr;
151 	hdr.elf_hdr.e_phoff = offsetof(ksyms_header_t, text_phdr);
152 	hdr.elf_hdr.e_shoff = offsetof(ksyms_header_t, shdr);
153 	hdr.elf_hdr.e_phnum = 2;
154 	hdr.elf_hdr.e_shnum = KSHDR_NUM;
155 	hdr.elf_hdr.e_shstrndx = KSHDR_SHSTRTAB;
156 
157 	hdr.text_phdr.p_type = PT_LOAD;
158 	hdr.text_phdr.p_vaddr = (Addr)s_text;
159 	hdr.text_phdr.p_memsz = (Word)(e_text - s_text);
160 	hdr.text_phdr.p_flags = PF_R | PF_X;
161 
162 	hdr.data_phdr.p_type = PT_LOAD;
163 	hdr.data_phdr.p_vaddr = (Addr)s_data;
164 	hdr.data_phdr.p_memsz = (Word)(e_data - s_data);
165 	hdr.data_phdr.p_flags = PF_R | PF_W | PF_X;
166 
167 	shp = &hdr.shdr[KSHDR_SYMTAB];
168 	shp->sh_name = 1;	/* ksyms_shstrtab[1] = ".symtab" */
169 	shp->sh_type = SHT_SYMTAB;
170 	shp->sh_offset = kw.kw_size[KW_HEADER];
171 	shp->sh_size = kw.kw_size[KW_LOCALS] + kw.kw_size[KW_GLOBALS];
172 	shp->sh_link = KSHDR_STRTAB;
173 	shp->sh_info = kw.kw_size[KW_LOCALS] / sizeof (Sym);
174 	shp->sh_addralign = sizeof (Addr);
175 	shp->sh_entsize = sizeof (Sym);
176 
177 	shp = &hdr.shdr[KSHDR_STRTAB];
178 	shp->sh_name = 9;	/* ksyms_shstrtab[9] = ".strtab" */
179 	shp->sh_type = SHT_STRTAB;
180 	shp->sh_offset = kw.kw_size[KW_HEADER] +
181 	    kw.kw_size[KW_LOCALS] + kw.kw_size[KW_GLOBALS];
182 	shp->sh_size = kw.kw_size[KW_STRINGS];
183 	shp->sh_addralign = 1;
184 
185 	shp = &hdr.shdr[KSHDR_SHSTRTAB];
186 	shp->sh_name = 17;	/* ksyms_shstrtab[17] = ".shstrtab" */
187 	shp->sh_type = SHT_STRTAB;
188 	shp->sh_offset = offsetof(ksyms_header_t, shstrings);
189 	shp->sh_size = sizeof (ksyms_shstrtab);
190 	shp->sh_addralign = 1;
191 
192 	bcopy(ksyms_shstrtab, hdr.shstrings, sizeof (ksyms_shstrtab));
193 
194 	/*
195 	 * Emit the symbol table.
196 	 */
197 	size += ksyms_walk(&kw, buf, (bufsize - size), emit, &hdr,
198 					    KW_HEADER);
199 	size += ksyms_walk(&kw, buf, (bufsize - size), emit,
200 					    NULL, KW_LOCALS);
201 	size += ksyms_walk(&kw, buf, (bufsize - size), emit,
202 					    NULL, KW_GLOBALS);
203 	size += ksyms_walk(&kw, buf, (bufsize - size), emit, NULL,
204 					    KW_STRINGS);
205 
206 	rw_exit(&ksyms_lock);
207 
208 	return ((size_t)size);
209 }
210