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 
21 static int ksym_cmp(const void *p1, const void *p2)
22 {
23 	return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
24 }
25 
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 
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 
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  */
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 
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 
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 
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