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
17static struct ksym syms[MAX_SYMS];
18static int sym_cnt;
19
20static int ksym_cmp(const void *p1, const void *p2)
21{
22	return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
23}
24
25int 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
51struct 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
81long 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 */
96int 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
115out:
116	fclose(f);
117	return err;
118}
119
120void 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