1 /*
2 * symbols.c: in-kernel printing of symbolic oopses and stack traces.
3 *
4 * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
5 *
6 * ChangeLog:
7 *
8 * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
9 * Changed the compression method from stem compression to "table lookup"
10 * compression (see tools/symbols.c for a more complete description)
11 */
12
13 #include <xen/symbols.h>
14 #include <xen/kernel.h>
15 #include <xen/init.h>
16 #include <xen/lib.h>
17 #include <xen/string.h>
18 #include <xen/spinlock.h>
19 #include <xen/virtual_region.h>
20 #include <public/platform.h>
21 #include <xen/guest_access.h>
22
23 #ifdef SYMBOLS_ORIGIN
24 extern const unsigned int symbols_offsets[];
25 #define symbols_address(n) (SYMBOLS_ORIGIN + symbols_offsets[n])
26 #else
27 extern const unsigned long symbols_addresses[];
28 #define symbols_address(n) symbols_addresses[n]
29 #endif
30 extern const unsigned int symbols_num_syms;
31 extern const u8 symbols_names[];
32
33 extern const struct symbol_offset symbols_sorted_offsets[];
34
35 extern const u8 symbols_token_table[];
36 extern const u16 symbols_token_index[];
37
38 extern const unsigned int symbols_markers[];
39
40 /* expand a compressed symbol data into the resulting uncompressed string,
41 given the offset to where the symbol is in the compressed stream */
symbols_expand_symbol(unsigned int off,char * result)42 static unsigned int symbols_expand_symbol(unsigned int off, char *result)
43 {
44 int len, skipped_first = 0;
45 const u8 *tptr, *data;
46
47 /* get the compressed symbol length from the first symbol byte */
48 data = &symbols_names[off];
49 len = *data;
50 data++;
51
52 /* update the offset to return the offset for the next symbol on
53 * the compressed stream */
54 off += len + 1;
55
56 /* for every byte on the compressed symbol data, copy the table
57 entry for that byte */
58 while(len) {
59 tptr = &symbols_token_table[ symbols_token_index[*data] ];
60 data++;
61 len--;
62
63 while (*tptr) {
64 if(skipped_first) {
65 *result = *tptr;
66 result++;
67 } else
68 skipped_first = 1;
69 tptr++;
70 }
71 }
72
73 *result = '\0';
74
75 /* return to offset to the next symbol */
76 return off;
77 }
78
79 /* find the offset on the compressed stream given and index in the
80 * symbols array */
get_symbol_offset(unsigned long pos)81 static unsigned int get_symbol_offset(unsigned long pos)
82 {
83 const u8 *name;
84 int i;
85
86 /* use the closest marker we have. We have markers every 256 positions,
87 * so that should be close enough */
88 name = &symbols_names[ symbols_markers[pos>>8] ];
89
90 /* sequentially scan all the symbols up to the point we're searching for.
91 * Every symbol is stored in a [<len>][<len> bytes of data] format, so we
92 * just need to add the len to the current pointer for every symbol we
93 * wish to skip */
94 for(i = 0; i < (pos&0xFF); i++)
95 name = name + (*name) + 1;
96
97 return name - symbols_names;
98 }
99
is_active_kernel_text(unsigned long addr)100 bool_t is_active_kernel_text(unsigned long addr)
101 {
102 return !!find_text_region(addr);
103 }
104
symbols_lookup(unsigned long addr,unsigned long * symbolsize,unsigned long * offset,char * namebuf)105 const char *symbols_lookup(unsigned long addr,
106 unsigned long *symbolsize,
107 unsigned long *offset,
108 char *namebuf)
109 {
110 unsigned long i, low, high, mid;
111 unsigned long symbol_end = 0;
112 const struct virtual_region *region;
113
114 namebuf[KSYM_NAME_LEN] = 0;
115 namebuf[0] = 0;
116
117 region = find_text_region(addr);
118 if (!region)
119 return NULL;
120
121 if (region->symbols_lookup)
122 return region->symbols_lookup(addr, symbolsize, offset, namebuf);
123
124 /* do a binary search on the sorted symbols_addresses array */
125 low = 0;
126 high = symbols_num_syms;
127
128 while (high-low > 1) {
129 mid = (low + high) / 2;
130 if (symbols_address(mid) <= addr) low = mid;
131 else high = mid;
132 }
133
134 /* search for the first aliased symbol. Aliased symbols are
135 symbols with the same address */
136 while (low && symbols_address(low - 1) == symbols_address(low))
137 --low;
138
139 /* Grab name */
140 symbols_expand_symbol(get_symbol_offset(low), namebuf);
141
142 /* Search for next non-aliased symbol */
143 for (i = low + 1; i < symbols_num_syms; i++) {
144 if (symbols_address(i) > symbols_address(low)) {
145 symbol_end = symbols_address(i);
146 break;
147 }
148 }
149
150 /* if we found no next symbol, we use the end of the section */
151 if (!symbol_end)
152 symbol_end = is_kernel_inittext(addr) ?
153 (unsigned long)_einittext : (unsigned long)_etext;
154
155 *symbolsize = symbol_end - symbols_address(low);
156 *offset = addr - symbols_address(low);
157 return namebuf;
158 }
159
160 /*
161 * Get symbol type information. This is encoded as a single char at the
162 * beginning of the symbol name.
163 */
symbols_get_symbol_type(unsigned int off)164 static char symbols_get_symbol_type(unsigned int off)
165 {
166 /*
167 * Get just the first code, look it up in the token table,
168 * and return the first char from this token.
169 */
170 return symbols_token_table[symbols_token_index[symbols_names[off + 1]]];
171 }
172
xensyms_read(uint32_t * symnum,char * type,unsigned long * address,char * name)173 int xensyms_read(uint32_t *symnum, char *type,
174 unsigned long *address, char *name)
175 {
176 /*
177 * Symbols are most likely accessed sequentially so we remember position
178 * from previous read. This can help us avoid the extra call to
179 * get_symbol_offset().
180 */
181 static uint64_t next_symbol, next_offset;
182 static DEFINE_SPINLOCK(symbols_mutex);
183
184 if ( *symnum > symbols_num_syms )
185 return -ERANGE;
186 if ( *symnum == symbols_num_syms )
187 {
188 /* No more symbols */
189 name[0] = '\0';
190 return 0;
191 }
192
193 spin_lock(&symbols_mutex);
194
195 if ( *symnum == 0 )
196 next_offset = next_symbol = 0;
197 if ( next_symbol != *symnum )
198 /* Non-sequential access */
199 next_offset = get_symbol_offset(*symnum);
200
201 *type = symbols_get_symbol_type(next_offset);
202 next_offset = symbols_expand_symbol(next_offset, name);
203 *address = symbols_address(*symnum);
204
205 next_symbol = ++*symnum;
206
207 spin_unlock(&symbols_mutex);
208
209 return 0;
210 }
211
symbols_lookup_by_name(const char * symname)212 unsigned long symbols_lookup_by_name(const char *symname)
213 {
214 char name[KSYM_NAME_LEN + 1];
215 #ifdef CONFIG_FAST_SYMBOL_LOOKUP
216 unsigned long low, high;
217 #else
218 uint32_t symnum = 0;
219 char type;
220 unsigned long addr;
221 int rc;
222 #endif
223
224 if ( *symname == '\0' )
225 return 0;
226
227 #ifdef CONFIG_FAST_SYMBOL_LOOKUP
228 low = 0;
229 high = symbols_num_syms;
230 while ( low < high )
231 {
232 unsigned long mid = low + ((high - low) / 2);
233 const struct symbol_offset *s;
234 int rc;
235
236 s = &symbols_sorted_offsets[mid];
237 (void)symbols_expand_symbol(s->stream, name);
238 /* Format is: [filename]#<symbol>. symbols_expand_symbol eats type.*/
239 rc = strcmp(symname, name);
240 if ( rc < 0 )
241 high = mid;
242 else if ( rc > 0 )
243 low = mid + 1;
244 else
245 return symbols_address(s->addr);
246 }
247 #else
248 do {
249 rc = xensyms_read(&symnum, &type, &addr, name);
250 if ( rc )
251 break;
252
253 if ( !strcmp(name, symname) )
254 return addr;
255
256 } while ( name[0] != '\0' );
257
258 #endif
259 return 0;
260 }
261
262 /*
263 * Local variables:
264 * mode: C
265 * c-file-style: "BSD"
266 * c-basic-offset: 4
267 * tab-width: 4
268 * indent-tabs-mode: nil
269 * End:
270 */
271