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