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1/*
2 * jvmti_agent.c: JVMTI agent interface
3 *
4 * Adapted from the Oprofile code in opagent.c:
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 *
19 * Copyright 2007 OProfile authors
20 * Jens Wilke
21 * Daniel Hansel
22 * Copyright IBM Corporation 2007
23 */
24#include <sys/types.h>
25#include <sys/stat.h> /* for mkdir() */
26#include <stdio.h>
27#include <errno.h>
28#include <string.h>
29#include <stdlib.h>
30#include <stdint.h>
31#include <limits.h>
32#include <fcntl.h>
33#include <unistd.h>
34#include <time.h>
35#include <sys/mman.h>
36#include <syscall.h> /* for gettid() */
37#include <err.h>
38
39#include "jvmti_agent.h"
40#include "../util/jitdump.h"
41
42#define JIT_LANG "java"
43
44static char jit_path[PATH_MAX];
45static void *marker_addr;
46
47static inline pid_t gettid(void)
48{
49 return (pid_t)syscall(__NR_gettid);
50}
51
52static int get_e_machine(struct jitheader *hdr)
53{
54 ssize_t sret;
55 char id[16];
56 int fd, ret = -1;
57 struct {
58 uint16_t e_type;
59 uint16_t e_machine;
60 } info;
61
62 fd = open("/proc/self/exe", O_RDONLY);
63 if (fd == -1)
64 return -1;
65
66 sret = read(fd, id, sizeof(id));
67 if (sret != sizeof(id))
68 goto error;
69
70 /* check ELF signature */
71 if (id[0] != 0x7f || id[1] != 'E' || id[2] != 'L' || id[3] != 'F')
72 goto error;
73
74 sret = read(fd, &info, sizeof(info));
75 if (sret != sizeof(info))
76 goto error;
77
78 hdr->elf_mach = info.e_machine;
79 ret = 0;
80error:
81 close(fd);
82 return ret;
83}
84
85static int use_arch_timestamp;
86
87static inline uint64_t
88get_arch_timestamp(void)
89{
90#if defined(__i386__) || defined(__x86_64__)
91 unsigned int low, high;
92
93 asm volatile("rdtsc" : "=a" (low), "=d" (high));
94
95 return low | ((uint64_t)high) << 32;
96#else
97 return 0;
98#endif
99}
100
101#define NSEC_PER_SEC 1000000000
102static int perf_clk_id = CLOCK_MONOTONIC;
103
104static inline uint64_t
105timespec_to_ns(const struct timespec *ts)
106{
107 return ((uint64_t) ts->tv_sec * NSEC_PER_SEC) + ts->tv_nsec;
108}
109
110static inline uint64_t
111perf_get_timestamp(void)
112{
113 struct timespec ts;
114 int ret;
115
116 if (use_arch_timestamp)
117 return get_arch_timestamp();
118
119 ret = clock_gettime(perf_clk_id, &ts);
120 if (ret)
121 return 0;
122
123 return timespec_to_ns(&ts);
124}
125
126static int
127debug_cache_init(void)
128{
129 char str[32];
130 char *base, *p;
131 struct tm tm;
132 time_t t;
133 int ret;
134
135 time(&t);
136 localtime_r(&t, &tm);
137
138 base = getenv("JITDUMPDIR");
139 if (!base)
140 base = getenv("HOME");
141 if (!base)
142 base = ".";
143
144 strftime(str, sizeof(str), JIT_LANG"-jit-%Y%m%d", &tm);
145
146 snprintf(jit_path, PATH_MAX - 1, "%s/.debug/", base);
147
148 ret = mkdir(jit_path, 0755);
149 if (ret == -1) {
150 if (errno != EEXIST) {
151 warn("jvmti: cannot create jit cache dir %s", jit_path);
152 return -1;
153 }
154 }
155
156 snprintf(jit_path, PATH_MAX - 1, "%s/.debug/jit", base);
157 ret = mkdir(jit_path, 0755);
158 if (ret == -1) {
159 if (errno != EEXIST) {
160 warn("cannot create jit cache dir %s", jit_path);
161 return -1;
162 }
163 }
164
165 snprintf(jit_path, PATH_MAX - 1, "%s/.debug/jit/%s.XXXXXXXX", base, str);
166
167 p = mkdtemp(jit_path);
168 if (p != jit_path) {
169 warn("cannot create jit cache dir %s", jit_path);
170 return -1;
171 }
172
173 return 0;
174}
175
176static int
177perf_open_marker_file(int fd)
178{
179 long pgsz;
180
181 pgsz = sysconf(_SC_PAGESIZE);
182 if (pgsz == -1)
183 return -1;
184
185 /*
186 * we mmap the jitdump to create an MMAP RECORD in perf.data file.
187 * The mmap is captured either live (perf record running when we mmap)
188 * or in deferred mode, via /proc/PID/maps
189 * the MMAP record is used as a marker of a jitdump file for more meta
190 * data info about the jitted code. Perf report/annotate detect this
191 * special filename and process the jitdump file.
192 *
193 * mapping must be PROT_EXEC to ensure it is captured by perf record
194 * even when not using -d option
195 */
196 marker_addr = mmap(NULL, pgsz, PROT_READ|PROT_EXEC, MAP_PRIVATE, fd, 0);
197 return (marker_addr == MAP_FAILED) ? -1 : 0;
198}
199
200static void
201perf_close_marker_file(void)
202{
203 long pgsz;
204
205 if (!marker_addr)
206 return;
207
208 pgsz = sysconf(_SC_PAGESIZE);
209 if (pgsz == -1)
210 return;
211
212 munmap(marker_addr, pgsz);
213}
214
215static void
216init_arch_timestamp(void)
217{
218 char *str = getenv("JITDUMP_USE_ARCH_TIMESTAMP");
219
220 if (!str || !*str || !strcmp(str, "0"))
221 return;
222
223 use_arch_timestamp = 1;
224}
225
226void *jvmti_open(void)
227{
228 char dump_path[PATH_MAX];
229 struct jitheader header;
230 int fd;
231 FILE *fp;
232
233 init_arch_timestamp();
234
235 /*
236 * check if clockid is supported
237 */
238 if (!perf_get_timestamp()) {
239 if (use_arch_timestamp)
240 warnx("jvmti: arch timestamp not supported");
241 else
242 warnx("jvmti: kernel does not support %d clock id", perf_clk_id);
243 }
244
245 memset(&header, 0, sizeof(header));
246
247 debug_cache_init();
248
249 /*
250 * jitdump file name
251 */
252 snprintf(dump_path, PATH_MAX, "%s/jit-%i.dump", jit_path, getpid());
253
254 fd = open(dump_path, O_CREAT|O_TRUNC|O_RDWR, 0666);
255 if (fd == -1)
256 return NULL;
257
258 /*
259 * create perf.data maker for the jitdump file
260 */
261 if (perf_open_marker_file(fd)) {
262 warnx("jvmti: failed to create marker file");
263 return NULL;
264 }
265
266 fp = fdopen(fd, "w+");
267 if (!fp) {
268 warn("jvmti: cannot create %s", dump_path);
269 close(fd);
270 goto error;
271 }
272
273 warnx("jvmti: jitdump in %s", dump_path);
274
275 if (get_e_machine(&header)) {
276 warn("get_e_machine failed\n");
277 goto error;
278 }
279
280 header.magic = JITHEADER_MAGIC;
281 header.version = JITHEADER_VERSION;
282 header.total_size = sizeof(header);
283 header.pid = getpid();
284
285 header.timestamp = perf_get_timestamp();
286
287 if (use_arch_timestamp)
288 header.flags |= JITDUMP_FLAGS_ARCH_TIMESTAMP;
289
290 if (!fwrite(&header, sizeof(header), 1, fp)) {
291 warn("jvmti: cannot write dumpfile header");
292 goto error;
293 }
294 return fp;
295error:
296 fclose(fp);
297 return NULL;
298}
299
300int
301jvmti_close(void *agent)
302{
303 struct jr_code_close rec;
304 FILE *fp = agent;
305
306 if (!fp) {
307 warnx("jvmti: invalid fd in close_agent");
308 return -1;
309 }
310
311 rec.p.id = JIT_CODE_CLOSE;
312 rec.p.total_size = sizeof(rec);
313
314 rec.p.timestamp = perf_get_timestamp();
315
316 if (!fwrite(&rec, sizeof(rec), 1, fp))
317 return -1;
318
319 fclose(fp);
320
321 fp = NULL;
322
323 perf_close_marker_file();
324
325 return 0;
326}
327
328int
329jvmti_write_code(void *agent, char const *sym,
330 uint64_t vma, void const *code, unsigned int const size)
331{
332 static int code_generation = 1;
333 struct jr_code_load rec;
334 size_t sym_len;
335 FILE *fp = agent;
336 int ret = -1;
337
338 /* don't care about 0 length function, no samples */
339 if (size == 0)
340 return 0;
341
342 if (!fp) {
343 warnx("jvmti: invalid fd in write_native_code");
344 return -1;
345 }
346
347 sym_len = strlen(sym) + 1;
348
349 rec.p.id = JIT_CODE_LOAD;
350 rec.p.total_size = sizeof(rec) + sym_len;
351 rec.p.timestamp = perf_get_timestamp();
352
353 rec.code_size = size;
354 rec.vma = vma;
355 rec.code_addr = vma;
356 rec.pid = getpid();
357 rec.tid = gettid();
358
359 if (code)
360 rec.p.total_size += size;
361
362 /*
363 * If JVM is multi-threaded, nultiple concurrent calls to agent
364 * may be possible, so protect file writes
365 */
366 flockfile(fp);
367
368 /*
369 * get code index inside lock to avoid race condition
370 */
371 rec.code_index = code_generation++;
372
373 ret = fwrite_unlocked(&rec, sizeof(rec), 1, fp);
374 fwrite_unlocked(sym, sym_len, 1, fp);
375
376 if (code)
377 fwrite_unlocked(code, size, 1, fp);
378
379 funlockfile(fp);
380
381 ret = 0;
382
383 return ret;
384}
385
386int
387jvmti_write_debug_info(void *agent, uint64_t code,
388 int nr_lines, jvmti_line_info_t *li,
389 const char * const * file_names)
390{
391 struct jr_code_debug_info rec;
392 size_t sret, len, size, flen = 0;
393 uint64_t addr;
394 FILE *fp = agent;
395 int i;
396
397 /*
398 * no entry to write
399 */
400 if (!nr_lines)
401 return 0;
402
403 if (!fp) {
404 warnx("jvmti: invalid fd in write_debug_info");
405 return -1;
406 }
407
408 for (i = 0; i < nr_lines; ++i) {
409 flen += strlen(file_names[i]) + 1;
410 }
411
412 rec.p.id = JIT_CODE_DEBUG_INFO;
413 size = sizeof(rec);
414 rec.p.timestamp = perf_get_timestamp();
415 rec.code_addr = (uint64_t)(uintptr_t)code;
416 rec.nr_entry = nr_lines;
417
418 /*
419 * on disk source line info layout:
420 * uint64_t : addr
421 * int : line number
422 * int : column discriminator
423 * file[] : source file name
424 */
425 size += nr_lines * sizeof(struct debug_entry);
426 size += flen;
427 rec.p.total_size = size;
428
429 /*
430 * If JVM is multi-threaded, nultiple concurrent calls to agent
431 * may be possible, so protect file writes
432 */
433 flockfile(fp);
434
435 sret = fwrite_unlocked(&rec, sizeof(rec), 1, fp);
436 if (sret != 1)
437 goto error;
438
439 for (i = 0; i < nr_lines; i++) {
440
441 addr = (uint64_t)li[i].pc;
442 len = sizeof(addr);
443 sret = fwrite_unlocked(&addr, len, 1, fp);
444 if (sret != 1)
445 goto error;
446
447 len = sizeof(li[0].line_number);
448 sret = fwrite_unlocked(&li[i].line_number, len, 1, fp);
449 if (sret != 1)
450 goto error;
451
452 len = sizeof(li[0].discrim);
453 sret = fwrite_unlocked(&li[i].discrim, len, 1, fp);
454 if (sret != 1)
455 goto error;
456
457 sret = fwrite_unlocked(file_names[i], strlen(file_names[i]) + 1, 1, fp);
458 if (sret != 1)
459 goto error;
460 }
461 funlockfile(fp);
462 return 0;
463error:
464 funlockfile(fp);
465 return -1;
466}