1 // SPDX-License-Identifier: GPL-2.0
2 #include <ctype.h>
3 #include <stdio.h>
4 #include <stdlib.h>
5 #include <string.h>
6 #include <assert.h>
7 #include <errno.h>
8 #include <fcntl.h>
9 #include <poll.h>
10 #include <unistd.h>
11 #include <linux/perf_event.h>
12 #include <sys/mman.h>
13 #include "trace_helpers.h"
14
15 #define DEBUGFS "/sys/kernel/debug/tracing/"
16
17 #define MAX_SYMS 300000
18 static struct ksym syms[MAX_SYMS];
19 static int sym_cnt;
20
ksym_cmp(const void * p1,const void * p2)21 static int ksym_cmp(const void *p1, const void *p2)
22 {
23 return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
24 }
25
load_kallsyms_refresh(void)26 int load_kallsyms_refresh(void)
27 {
28 FILE *f;
29 char func[256], buf[256];
30 char symbol;
31 void *addr;
32 int i = 0;
33
34 sym_cnt = 0;
35
36 f = fopen("/proc/kallsyms", "r");
37 if (!f)
38 return -ENOENT;
39
40 while (fgets(buf, sizeof(buf), f)) {
41 if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
42 break;
43 if (!addr)
44 continue;
45 syms[i].addr = (long) addr;
46 syms[i].name = strdup(func);
47 i++;
48 }
49 fclose(f);
50 sym_cnt = i;
51 qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
52 return 0;
53 }
54
load_kallsyms(void)55 int load_kallsyms(void)
56 {
57 /*
58 * This is called/used from multiplace places,
59 * load symbols just once.
60 */
61 if (sym_cnt)
62 return 0;
63 return load_kallsyms_refresh();
64 }
65
ksym_search(long key)66 struct ksym *ksym_search(long key)
67 {
68 int start = 0, end = sym_cnt;
69 int result;
70
71 /* kallsyms not loaded. return NULL */
72 if (sym_cnt <= 0)
73 return NULL;
74
75 while (start < end) {
76 size_t mid = start + (end - start) / 2;
77
78 result = key - syms[mid].addr;
79 if (result < 0)
80 end = mid;
81 else if (result > 0)
82 start = mid + 1;
83 else
84 return &syms[mid];
85 }
86
87 if (start >= 1 && syms[start - 1].addr < key &&
88 key < syms[start].addr)
89 /* valid ksym */
90 return &syms[start - 1];
91
92 /* out of range. return _stext */
93 return &syms[0];
94 }
95
ksym_get_addr(const char * name)96 long ksym_get_addr(const char *name)
97 {
98 int i;
99
100 for (i = 0; i < sym_cnt; i++) {
101 if (strcmp(syms[i].name, name) == 0)
102 return syms[i].addr;
103 }
104
105 return 0;
106 }
107
108 /* open kallsyms and read symbol addresses on the fly. Without caching all symbols,
109 * this is faster than load + find.
110 */
kallsyms_find(const char * sym,unsigned long long * addr)111 int kallsyms_find(const char *sym, unsigned long long *addr)
112 {
113 char type, name[500];
114 unsigned long long value;
115 int err = 0;
116 FILE *f;
117
118 f = fopen("/proc/kallsyms", "r");
119 if (!f)
120 return -EINVAL;
121
122 while (fscanf(f, "%llx %c %499s%*[^\n]\n", &value, &type, name) > 0) {
123 if (strcmp(name, sym) == 0) {
124 *addr = value;
125 goto out;
126 }
127 }
128 err = -ENOENT;
129
130 out:
131 fclose(f);
132 return err;
133 }
134
read_trace_pipe(void)135 void read_trace_pipe(void)
136 {
137 int trace_fd;
138
139 trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
140 if (trace_fd < 0)
141 return;
142
143 while (1) {
144 static char buf[4096];
145 ssize_t sz;
146
147 sz = read(trace_fd, buf, sizeof(buf) - 1);
148 if (sz > 0) {
149 buf[sz] = 0;
150 puts(buf);
151 }
152 }
153 }
154
get_uprobe_offset(const void * addr)155 ssize_t get_uprobe_offset(const void *addr)
156 {
157 size_t start, end, base;
158 char buf[256];
159 bool found = false;
160 FILE *f;
161
162 f = fopen("/proc/self/maps", "r");
163 if (!f)
164 return -errno;
165
166 while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &base) == 4) {
167 if (buf[2] == 'x' && (uintptr_t)addr >= start && (uintptr_t)addr < end) {
168 found = true;
169 break;
170 }
171 }
172
173 fclose(f);
174
175 if (!found)
176 return -ESRCH;
177
178 #if defined(__powerpc64__) && defined(_CALL_ELF) && _CALL_ELF == 2
179
180 #define OP_RT_RA_MASK 0xffff0000UL
181 #define LIS_R2 0x3c400000UL
182 #define ADDIS_R2_R12 0x3c4c0000UL
183 #define ADDI_R2_R2 0x38420000UL
184
185 /*
186 * A PPC64 ABIv2 function may have a local and a global entry
187 * point. We need to use the local entry point when patching
188 * functions, so identify and step over the global entry point
189 * sequence.
190 *
191 * The global entry point sequence is always of the form:
192 *
193 * addis r2,r12,XXXX
194 * addi r2,r2,XXXX
195 *
196 * A linker optimisation may convert the addis to lis:
197 *
198 * lis r2,XXXX
199 * addi r2,r2,XXXX
200 */
201 {
202 const u32 *insn = (const u32 *)(uintptr_t)addr;
203
204 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
205 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
206 ((*(insn + 1) & OP_RT_RA_MASK) == ADDI_R2_R2))
207 return (uintptr_t)(insn + 2) - start + base;
208 }
209 #endif
210 return (uintptr_t)addr - start + base;
211 }
212
get_rel_offset(uintptr_t addr)213 ssize_t get_rel_offset(uintptr_t addr)
214 {
215 size_t start, end, offset;
216 char buf[256];
217 FILE *f;
218
219 f = fopen("/proc/self/maps", "r");
220 if (!f)
221 return -errno;
222
223 while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &offset) == 4) {
224 if (addr >= start && addr < end) {
225 fclose(f);
226 return (size_t)addr - start + offset;
227 }
228 }
229
230 fclose(f);
231 return -EINVAL;
232 }
233