1 // SPDX-License-Identifier: GPL-2.0
2 #include <stdio.h>
3 #include <stdlib.h>
4 #include <string.h>
5 #include <assert.h>
6 #include <errno.h>
7 #include <fcntl.h>
8 #include <poll.h>
9 #include <unistd.h>
10 #include <linux/perf_event.h>
11 #include <sys/mman.h>
12 #include "trace_helpers.h"
13
14 #define DEBUGFS "/sys/kernel/debug/tracing/"
15
16 #define MAX_SYMS 300000
17 static struct ksym syms[MAX_SYMS];
18 static int sym_cnt;
19
ksym_cmp(const void * p1,const void * p2)20 static int ksym_cmp(const void *p1, const void *p2)
21 {
22 return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
23 }
24
load_kallsyms(void)25 int load_kallsyms(void)
26 {
27 FILE *f = fopen("/proc/kallsyms", "r");
28 char func[256], buf[256];
29 char symbol;
30 void *addr;
31 int i = 0;
32
33 if (!f)
34 return -ENOENT;
35
36 while (fgets(buf, sizeof(buf), f)) {
37 if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
38 break;
39 if (!addr)
40 continue;
41 syms[i].addr = (long) addr;
42 syms[i].name = strdup(func);
43 i++;
44 }
45 fclose(f);
46 sym_cnt = i;
47 qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
48 return 0;
49 }
50
ksym_search(long key)51 struct ksym *ksym_search(long key)
52 {
53 int start = 0, end = sym_cnt;
54 int result;
55
56 /* kallsyms not loaded. return NULL */
57 if (sym_cnt <= 0)
58 return NULL;
59
60 while (start < end) {
61 size_t mid = start + (end - start) / 2;
62
63 result = key - syms[mid].addr;
64 if (result < 0)
65 end = mid;
66 else if (result > 0)
67 start = mid + 1;
68 else
69 return &syms[mid];
70 }
71
72 if (start >= 1 && syms[start - 1].addr < key &&
73 key < syms[start].addr)
74 /* valid ksym */
75 return &syms[start - 1];
76
77 /* out of range. return _stext */
78 return &syms[0];
79 }
80
ksym_get_addr(const char * name)81 long ksym_get_addr(const char *name)
82 {
83 int i;
84
85 for (i = 0; i < sym_cnt; i++) {
86 if (strcmp(syms[i].name, name) == 0)
87 return syms[i].addr;
88 }
89
90 return 0;
91 }
92
93 /* open kallsyms and read symbol addresses on the fly. Without caching all symbols,
94 * this is faster than load + find.
95 */
kallsyms_find(const char * sym,unsigned long long * addr)96 int kallsyms_find(const char *sym, unsigned long long *addr)
97 {
98 char type, name[500];
99 unsigned long long value;
100 int err = 0;
101 FILE *f;
102
103 f = fopen("/proc/kallsyms", "r");
104 if (!f)
105 return -EINVAL;
106
107 while (fscanf(f, "%llx %c %499s%*[^\n]\n", &value, &type, name) > 0) {
108 if (strcmp(name, sym) == 0) {
109 *addr = value;
110 goto out;
111 }
112 }
113 err = -ENOENT;
114
115 out:
116 fclose(f);
117 return err;
118 }
119
read_trace_pipe(void)120 void read_trace_pipe(void)
121 {
122 int trace_fd;
123
124 trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
125 if (trace_fd < 0)
126 return;
127
128 while (1) {
129 static char buf[4096];
130 ssize_t sz;
131
132 sz = read(trace_fd, buf, sizeof(buf) - 1);
133 if (sz > 0) {
134 buf[sz] = 0;
135 puts(buf);
136 }
137 }
138 }
139
