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
140 #if defined(__powerpc64__) && defined(_CALL_ELF) && _CALL_ELF == 2
141
142 #define OP_RT_RA_MASK 0xffff0000UL
143 #define LIS_R2 0x3c400000UL
144 #define ADDIS_R2_R12 0x3c4c0000UL
145 #define ADDI_R2_R2 0x38420000UL
146
get_uprobe_offset(const void * addr,ssize_t base)147 ssize_t get_uprobe_offset(const void *addr, ssize_t base)
148 {
149 u32 *insn = (u32 *)(uintptr_t)addr;
150
151 /*
152 * A PPC64 ABIv2 function may have a local and a global entry
153 * point. We need to use the local entry point when patching
154 * functions, so identify and step over the global entry point
155 * sequence.
156 *
157 * The global entry point sequence is always of the form:
158 *
159 * addis r2,r12,XXXX
160 * addi r2,r2,XXXX
161 *
162 * A linker optimisation may convert the addis to lis:
163 *
164 * lis r2,XXXX
165 * addi r2,r2,XXXX
166 */
167 if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
168 ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
169 ((*(insn + 1) & OP_RT_RA_MASK) == ADDI_R2_R2))
170 return (ssize_t)(insn + 2) - base;
171 else
172 return (uintptr_t)addr - base;
173 }
174
175 #else
176
get_uprobe_offset(const void * addr,ssize_t base)177 ssize_t get_uprobe_offset(const void *addr, ssize_t base)
178 {
179 return (uintptr_t)addr - base;
180 }
181
182 #endif
183
get_base_addr(void)184 ssize_t get_base_addr(void)
185 {
186 size_t start, offset;
187 char buf[256];
188 FILE *f;
189
190 f = fopen("/proc/self/maps", "r");
191 if (!f)
192 return -errno;
193
194 while (fscanf(f, "%zx-%*x %s %zx %*[^\n]\n",
195 &start, buf, &offset) == 3) {
196 if (strcmp(buf, "r-xp") == 0) {
197 fclose(f);
198 return start - offset;
199 }
200 }
201
202 fclose(f);
203 return -EINVAL;
204 }
205
get_rel_offset(uintptr_t addr)206 ssize_t get_rel_offset(uintptr_t addr)
207 {
208 size_t start, end, offset;
209 char buf[256];
210 FILE *f;
211
212 f = fopen("/proc/self/maps", "r");
213 if (!f)
214 return -errno;
215
216 while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &offset) == 4) {
217 if (addr >= start && addr < end) {
218 fclose(f);
219 return (size_t)addr - start + offset;
220 }
221 }
222
223 fclose(f);
224 return -EINVAL;
225 }
226