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