xref: /linux/tools/perf/jvmti/libjvmti.c (revision 4b4193256c8d3bc3a5397b5cd9494c2ad386317d)
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