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
17static int has_line_numbers;
18void *jvmti_agent;
19
20static 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
34static jvmtiError
35do_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
72static jvmtiError
73get_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
129static jvmtiError
130get_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
137static void
138copy_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
165static jvmtiError
166get_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
204free_class_sign_error:
205	(*jvmti)->Deallocate(jvmti, (unsigned char *)class_sign);
206free_file_name_error:
207	(*jvmti)->Deallocate(jvmti, (unsigned char *)file_name);
208
209	return ret;
210}
211
212static jvmtiError
213fill_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
229static void JNICALL
230compiled_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	}
309error:
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
323static void JNICALL
324code_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
337JNIEXPORT jint JNICALL
338Agent_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
412JNIEXPORT void JNICALL
413Agent_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