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