1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/compiler.h>
3 #include <linux/string.h>
4 #include <sys/types.h>
5 #include <stdio.h>
6 #include <string.h>
7 #include <stdlib.h>
8 #include <err.h>
9 #include <jvmti.h>
10 #ifdef HAVE_JVMTI_CMLR
11 #include <jvmticmlr.h>
12 #endif
13 #include <limits.h>
14
15 #include "jvmti_agent.h"
16
17 static int has_line_numbers;
18 void *jvmti_agent;
19
print_error(jvmtiEnv * jvmti,const char * msg,jvmtiError ret)20 static void print_error(jvmtiEnv *jvmti, const char *msg, jvmtiError ret)
21 {
22 char *err_msg = NULL;
23 jvmtiError err;
24 err = (*jvmti)->GetErrorName(jvmti, ret, &err_msg);
25 if (err == JVMTI_ERROR_NONE) {
26 warnx("%s failed with %s", msg, err_msg);
27 (*jvmti)->Deallocate(jvmti, (unsigned char *)err_msg);
28 } else {
29 warnx("%s failed with an unknown error %d", msg, ret);
30 }
31 }
32
33 #ifdef HAVE_JVMTI_CMLR
34 static jvmtiError
do_get_line_number(jvmtiEnv * jvmti,void * pc,jmethodID m,jint bci,jvmti_line_info_t * tab)35 do_get_line_number(jvmtiEnv *jvmti, void *pc, jmethodID m, jint bci,
36 jvmti_line_info_t *tab)
37 {
38 jint i, nr_lines = 0;
39 jvmtiLineNumberEntry *loc_tab = NULL;
40 jvmtiError ret;
41 jint src_line = -1;
42
43 ret = (*jvmti)->GetLineNumberTable(jvmti, m, &nr_lines, &loc_tab);
44 if (ret == JVMTI_ERROR_ABSENT_INFORMATION || ret == JVMTI_ERROR_NATIVE_METHOD) {
45 /* No debug information for this method */
46 return ret;
47 } else if (ret != JVMTI_ERROR_NONE) {
48 print_error(jvmti, "GetLineNumberTable", ret);
49 return ret;
50 }
51
52 for (i = 0; i < nr_lines && loc_tab[i].start_location <= bci; i++) {
53 src_line = i;
54 }
55
56 if (src_line != -1) {
57 tab->pc = (unsigned long)pc;
58 tab->line_number = loc_tab[src_line].line_number;
59 tab->discrim = 0; /* not yet used */
60 tab->methodID = m;
61
62 ret = JVMTI_ERROR_NONE;
63 } else {
64 ret = JVMTI_ERROR_ABSENT_INFORMATION;
65 }
66
67 (*jvmti)->Deallocate(jvmti, (unsigned char *)loc_tab);
68
69 return ret;
70 }
71
72 static jvmtiError
get_line_numbers(jvmtiEnv * jvmti,const void * compile_info,jvmti_line_info_t ** tab,int * nr_lines)73 get_line_numbers(jvmtiEnv *jvmti, const void *compile_info, jvmti_line_info_t **tab, int *nr_lines)
74 {
75 const jvmtiCompiledMethodLoadRecordHeader *hdr;
76 jvmtiCompiledMethodLoadInlineRecord *rec;
77 PCStackInfo *c;
78 jint ret;
79 int nr_total = 0;
80 int i, lines_total = 0;
81
82 if (!(tab && nr_lines))
83 return JVMTI_ERROR_NULL_POINTER;
84
85 /*
86 * Phase 1 -- get the number of lines necessary
87 */
88 for (hdr = compile_info; hdr != NULL; hdr = hdr->next) {
89 if (hdr->kind == JVMTI_CMLR_INLINE_INFO) {
90 rec = (jvmtiCompiledMethodLoadInlineRecord *)hdr;
91 nr_total += rec->numpcs;
92 }
93 }
94
95 if (nr_total == 0)
96 return JVMTI_ERROR_NOT_FOUND;
97
98 /*
99 * Phase 2 -- allocate big enough line table
100 */
101 *tab = malloc(nr_total * sizeof(**tab));
102 if (!*tab)
103 return JVMTI_ERROR_OUT_OF_MEMORY;
104
105 for (hdr = compile_info; hdr != NULL; hdr = hdr->next) {
106 if (hdr->kind == JVMTI_CMLR_INLINE_INFO) {
107 rec = (jvmtiCompiledMethodLoadInlineRecord *)hdr;
108 for (i = 0; i < rec->numpcs; i++) {
109 c = rec->pcinfo + i;
110 /*
111 * c->methods is the stack of inlined method calls
112 * at c->pc. [0] is the leaf method. Caller frames
113 * are ignored at the moment.
114 */
115 ret = do_get_line_number(jvmti, c->pc,
116 c->methods[0],
117 c->bcis[0],
118 *tab + lines_total);
119 if (ret == JVMTI_ERROR_NONE)
120 lines_total++;
121 }
122 }
123 }
124 *nr_lines = lines_total;
125 return JVMTI_ERROR_NONE;
126 }
127 #else /* HAVE_JVMTI_CMLR */
128
129 static jvmtiError
get_line_numbers(jvmtiEnv * jvmti __maybe_unused,const void * compile_info __maybe_unused,jvmti_line_info_t ** tab __maybe_unused,int * nr_lines __maybe_unused)130 get_line_numbers(jvmtiEnv *jvmti __maybe_unused, const void *compile_info __maybe_unused,
131 jvmti_line_info_t **tab __maybe_unused, int *nr_lines __maybe_unused)
132 {
133 return JVMTI_ERROR_NONE;
134 }
135 #endif /* HAVE_JVMTI_CMLR */
136
137 static void
copy_class_filename(const char * class_sign,const char * file_name,char * result,size_t max_length)138 copy_class_filename(const char * class_sign, const char * file_name, char * result, size_t max_length)
139 {
140 /*
141 * Assume path name is class hierarchy, this is a common practice with Java programs
142 */
143 if (*class_sign == 'L') {
144 int j, i = 0;
145 char *p = strrchr(class_sign, '/');
146 if (p) {
147 /* drop the 'L' prefix and copy up to the final '/' */
148 for (i = 0; i < (p - class_sign); i++)
149 result[i] = class_sign[i+1];
150 }
151 /*
152 * append file name, we use loops and not string ops to avoid modifying
153 * class_sign which is used later for the symbol name
154 */
155 for (j = 0; i < (max_length - 1) && file_name && j < strlen(file_name); j++, i++)
156 result[i] = file_name[j];
157
158 result[i] = '\0';
159 } else {
160 /* fallback case */
161 strlcpy(result, file_name, max_length);
162 }
163 }
164
165 static jvmtiError
get_source_filename(jvmtiEnv * jvmti,jmethodID methodID,char ** buffer)166 get_source_filename(jvmtiEnv *jvmti, jmethodID methodID, char ** buffer)
167 {
168 jvmtiError ret;
169 jclass decl_class;
170 char *file_name = NULL;
171 char *class_sign = NULL;
172 char fn[PATH_MAX];
173 size_t len;
174
175 ret = (*jvmti)->GetMethodDeclaringClass(jvmti, methodID, &decl_class);
176 if (ret != JVMTI_ERROR_NONE) {
177 print_error(jvmti, "GetMethodDeclaringClass", ret);
178 return ret;
179 }
180
181 ret = (*jvmti)->GetSourceFileName(jvmti, decl_class, &file_name);
182 if (ret != JVMTI_ERROR_NONE) {
183 print_error(jvmti, "GetSourceFileName", ret);
184 return ret;
185 }
186
187 ret = (*jvmti)->GetClassSignature(jvmti, decl_class, &class_sign, NULL);
188 if (ret != JVMTI_ERROR_NONE) {
189 print_error(jvmti, "GetClassSignature", ret);
190 goto free_file_name_error;
191 }
192
193 copy_class_filename(class_sign, file_name, fn, PATH_MAX);
194 len = strlen(fn);
195 *buffer = malloc((len + 1) * sizeof(char));
196 if (!*buffer) {
197 print_error(jvmti, "GetClassSignature", ret);
198 ret = JVMTI_ERROR_OUT_OF_MEMORY;
199 goto free_class_sign_error;
200 }
201 strcpy(*buffer, fn);
202 ret = JVMTI_ERROR_NONE;
203
204 free_class_sign_error:
205 (*jvmti)->Deallocate(jvmti, (unsigned char *)class_sign);
206 free_file_name_error:
207 (*jvmti)->Deallocate(jvmti, (unsigned char *)file_name);
208
209 return ret;
210 }
211
212 static jvmtiError
fill_source_filenames(jvmtiEnv * jvmti,int nr_lines,const jvmti_line_info_t * line_tab,char ** file_names)213 fill_source_filenames(jvmtiEnv *jvmti, int nr_lines,
214 const jvmti_line_info_t * line_tab,
215 char ** file_names)
216 {
217 int index;
218 jvmtiError ret;
219
220 for (index = 0; index < nr_lines; ++index) {
221 ret = get_source_filename(jvmti, line_tab[index].methodID, &(file_names[index]));
222 if (ret != JVMTI_ERROR_NONE)
223 return ret;
224 }
225
226 return JVMTI_ERROR_NONE;
227 }
228
229 static void JNICALL
compiled_method_load_cb(jvmtiEnv * jvmti,jmethodID method,jint code_size,void const * code_addr,jint map_length,jvmtiAddrLocationMap const * map,const void * compile_info)230 compiled_method_load_cb(jvmtiEnv *jvmti,
231 jmethodID method,
232 jint code_size,
233 void const *code_addr,
234 jint map_length,
235 jvmtiAddrLocationMap const *map,
236 const void *compile_info)
237 {
238 jvmti_line_info_t *line_tab = NULL;
239 char ** line_file_names = NULL;
240 jclass decl_class;
241 char *class_sign = NULL;
242 char *func_name = NULL;
243 char *func_sign = NULL;
244 uint64_t addr = (uint64_t)(uintptr_t)code_addr;
245 jvmtiError ret;
246 int nr_lines = 0; /* in line_tab[] */
247 size_t len;
248 int output_debug_info = 0;
249
250 ret = (*jvmti)->GetMethodDeclaringClass(jvmti, method,
251 &decl_class);
252 if (ret != JVMTI_ERROR_NONE) {
253 print_error(jvmti, "GetMethodDeclaringClass", ret);
254 return;
255 }
256
257 if (has_line_numbers && map && map_length) {
258 ret = get_line_numbers(jvmti, compile_info, &line_tab, &nr_lines);
259 if (ret != JVMTI_ERROR_NONE) {
260 if (ret != JVMTI_ERROR_NOT_FOUND) {
261 warnx("jvmti: cannot get line table for method");
262 }
263 nr_lines = 0;
264 } else if (nr_lines > 0) {
265 line_file_names = malloc(sizeof(char*) * nr_lines);
266 if (!line_file_names) {
267 warnx("jvmti: cannot allocate space for line table method names");
268 } else {
269 memset(line_file_names, 0, sizeof(char*) * nr_lines);
270 ret = fill_source_filenames(jvmti, nr_lines, line_tab, line_file_names);
271 if (ret != JVMTI_ERROR_NONE) {
272 warnx("jvmti: fill_source_filenames failed");
273 } else {
274 output_debug_info = 1;
275 }
276 }
277 }
278 }
279
280 ret = (*jvmti)->GetClassSignature(jvmti, decl_class,
281 &class_sign, NULL);
282 if (ret != JVMTI_ERROR_NONE) {
283 print_error(jvmti, "GetClassSignature", ret);
284 goto error;
285 }
286
287 ret = (*jvmti)->GetMethodName(jvmti, method, &func_name,
288 &func_sign, NULL);
289 if (ret != JVMTI_ERROR_NONE) {
290 print_error(jvmti, "GetMethodName", ret);
291 goto error;
292 }
293
294 /*
295 * write source line info record if we have it
296 */
297 if (output_debug_info)
298 if (jvmti_write_debug_info(jvmti_agent, addr, nr_lines, line_tab, (const char * const *) line_file_names))
299 warnx("jvmti: write_debug_info() failed");
300
301 len = strlen(func_name) + strlen(class_sign) + strlen(func_sign) + 2;
302 {
303 char str[len];
304 snprintf(str, len, "%s%s%s", class_sign, func_name, func_sign);
305
306 if (jvmti_write_code(jvmti_agent, str, addr, code_addr, code_size))
307 warnx("jvmti: write_code() failed");
308 }
309 error:
310 (*jvmti)->Deallocate(jvmti, (unsigned char *)func_name);
311 (*jvmti)->Deallocate(jvmti, (unsigned char *)func_sign);
312 (*jvmti)->Deallocate(jvmti, (unsigned char *)class_sign);
313 free(line_tab);
314 while (line_file_names && (nr_lines > 0)) {
315 if (line_file_names[nr_lines - 1]) {
316 free(line_file_names[nr_lines - 1]);
317 }
318 nr_lines -= 1;
319 }
320 free(line_file_names);
321 }
322
323 static void JNICALL
code_generated_cb(jvmtiEnv * jvmti,char const * name,void const * code_addr,jint code_size)324 code_generated_cb(jvmtiEnv *jvmti,
325 char const *name,
326 void const *code_addr,
327 jint code_size)
328 {
329 uint64_t addr = (uint64_t)(unsigned long)code_addr;
330 int ret;
331
332 ret = jvmti_write_code(jvmti_agent, name, addr, code_addr, code_size);
333 if (ret)
334 warnx("jvmti: write_code() failed for code_generated");
335 }
336
337 JNIEXPORT jint JNICALL
Agent_OnLoad(JavaVM * jvm,char * options,void * reserved __maybe_unused)338 Agent_OnLoad(JavaVM *jvm, char *options, void *reserved __maybe_unused)
339 {
340 jvmtiEventCallbacks cb;
341 jvmtiCapabilities caps1;
342 jvmtiJlocationFormat format;
343 jvmtiEnv *jvmti = NULL;
344 jint ret;
345
346 jvmti_agent = jvmti_open();
347 if (!jvmti_agent) {
348 warnx("jvmti: open_agent failed");
349 return -1;
350 }
351
352 /*
353 * Request a JVMTI interface version 1 environment
354 */
355 ret = (*jvm)->GetEnv(jvm, (void *)&jvmti, JVMTI_VERSION_1);
356 if (ret != JNI_OK) {
357 warnx("jvmti: jvmti version 1 not supported");
358 return -1;
359 }
360
361 /*
362 * acquire method_load capability, we require it
363 * request line numbers (optional)
364 */
365 memset(&caps1, 0, sizeof(caps1));
366 caps1.can_generate_compiled_method_load_events = 1;
367
368 ret = (*jvmti)->AddCapabilities(jvmti, &caps1);
369 if (ret != JVMTI_ERROR_NONE) {
370 print_error(jvmti, "AddCapabilities", ret);
371 return -1;
372 }
373 ret = (*jvmti)->GetJLocationFormat(jvmti, &format);
374 if (ret == JVMTI_ERROR_NONE && format == JVMTI_JLOCATION_JVMBCI) {
375 memset(&caps1, 0, sizeof(caps1));
376 caps1.can_get_line_numbers = 1;
377 caps1.can_get_source_file_name = 1;
378 ret = (*jvmti)->AddCapabilities(jvmti, &caps1);
379 if (ret == JVMTI_ERROR_NONE)
380 has_line_numbers = 1;
381 } else if (ret != JVMTI_ERROR_NONE)
382 print_error(jvmti, "GetJLocationFormat", ret);
383
384
385 memset(&cb, 0, sizeof(cb));
386
387 cb.CompiledMethodLoad = compiled_method_load_cb;
388 cb.DynamicCodeGenerated = code_generated_cb;
389
390 ret = (*jvmti)->SetEventCallbacks(jvmti, &cb, sizeof(cb));
391 if (ret != JVMTI_ERROR_NONE) {
392 print_error(jvmti, "SetEventCallbacks", ret);
393 return -1;
394 }
395
396 ret = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
397 JVMTI_EVENT_COMPILED_METHOD_LOAD, NULL);
398 if (ret != JVMTI_ERROR_NONE) {
399 print_error(jvmti, "SetEventNotificationMode(METHOD_LOAD)", ret);
400 return -1;
401 }
402
403 ret = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
404 JVMTI_EVENT_DYNAMIC_CODE_GENERATED, NULL);
405 if (ret != JVMTI_ERROR_NONE) {
406 print_error(jvmti, "SetEventNotificationMode(CODE_GENERATED)", ret);
407 return -1;
408 }
409 return 0;
410 }
411
412 JNIEXPORT void JNICALL
Agent_OnUnload(JavaVM * jvm __maybe_unused)413 Agent_OnUnload(JavaVM *jvm __maybe_unused)
414 {
415 int ret;
416
417 ret = jvmti_close(jvmti_agent);
418 if (ret)
419 errx(1, "Error: op_close_agent()");
420 }
421