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5584e2db IL |
1 | /* |
2 | * Linux perf perf-<pid>.map and jit-<pid>.dump integration. | |
3 | * | |
4 | * The jitdump spec can be found at [1]. | |
5 | * | |
6 | * [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/tools/perf/Documentation/jitdump-specification.txt | |
7 | * | |
8 | * SPDX-License-Identifier: GPL-2.0-or-later | |
9 | */ | |
10 | ||
11 | #include "qemu/osdep.h" | |
12 | #include "elf.h" | |
13 | #include "exec/exec-all.h" | |
14 | #include "qemu/timer.h" | |
15 | #include "tcg/tcg.h" | |
16 | ||
17 | #include "debuginfo.h" | |
18 | #include "perf.h" | |
19 | ||
20 | static FILE *safe_fopen_w(const char *path) | |
21 | { | |
22 | int saved_errno; | |
23 | FILE *f; | |
24 | int fd; | |
25 | ||
26 | /* Delete the old file, if any. */ | |
27 | unlink(path); | |
28 | ||
29 | /* Avoid symlink attacks by using O_CREAT | O_EXCL. */ | |
30 | fd = open(path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); | |
31 | if (fd == -1) { | |
32 | return NULL; | |
33 | } | |
34 | ||
35 | /* Convert fd to FILE*. */ | |
36 | f = fdopen(fd, "w"); | |
37 | if (f == NULL) { | |
38 | saved_errno = errno; | |
39 | close(fd); | |
40 | errno = saved_errno; | |
41 | return NULL; | |
42 | } | |
43 | ||
44 | return f; | |
45 | } | |
46 | ||
47 | static FILE *perfmap; | |
48 | ||
49 | void perf_enable_perfmap(void) | |
50 | { | |
51 | char map_file[32]; | |
52 | ||
53 | snprintf(map_file, sizeof(map_file), "/tmp/perf-%d.map", getpid()); | |
54 | perfmap = safe_fopen_w(map_file); | |
55 | if (perfmap == NULL) { | |
56 | warn_report("Could not open %s: %s, proceeding without perfmap", | |
57 | map_file, strerror(errno)); | |
58 | } | |
59 | } | |
60 | ||
61 | /* Get PC and size of code JITed for guest instruction #INSN. */ | |
62 | static void get_host_pc_size(uintptr_t *host_pc, uint16_t *host_size, | |
63 | const void *start, size_t insn) | |
64 | { | |
65 | uint16_t start_off = insn ? tcg_ctx->gen_insn_end_off[insn - 1] : 0; | |
66 | ||
67 | if (host_pc) { | |
68 | *host_pc = (uintptr_t)start + start_off; | |
69 | } | |
70 | if (host_size) { | |
71 | *host_size = tcg_ctx->gen_insn_end_off[insn] - start_off; | |
72 | } | |
73 | } | |
74 | ||
75 | static const char *pretty_symbol(const struct debuginfo_query *q, size_t *len) | |
76 | { | |
77 | static __thread char buf[64]; | |
78 | int tmp; | |
79 | ||
80 | if (!q->symbol) { | |
81 | tmp = snprintf(buf, sizeof(buf), "guest-0x%"PRIx64, q->address); | |
82 | if (len) { | |
83 | *len = MIN(tmp + 1, sizeof(buf)); | |
84 | } | |
85 | return buf; | |
86 | } | |
87 | ||
88 | if (!q->offset) { | |
89 | if (len) { | |
90 | *len = strlen(q->symbol) + 1; | |
91 | } | |
92 | return q->symbol; | |
93 | } | |
94 | ||
95 | tmp = snprintf(buf, sizeof(buf), "%s+0x%"PRIx64, q->symbol, q->offset); | |
96 | if (len) { | |
97 | *len = MIN(tmp + 1, sizeof(buf)); | |
98 | } | |
99 | return buf; | |
100 | } | |
101 | ||
102 | static void write_perfmap_entry(const void *start, size_t insn, | |
103 | const struct debuginfo_query *q) | |
104 | { | |
105 | uint16_t host_size; | |
106 | uintptr_t host_pc; | |
107 | ||
108 | get_host_pc_size(&host_pc, &host_size, start, insn); | |
109 | fprintf(perfmap, "%"PRIxPTR" %"PRIx16" %s\n", | |
110 | host_pc, host_size, pretty_symbol(q, NULL)); | |
111 | } | |
112 | ||
113 | static FILE *jitdump; | |
114 | ||
115 | #define JITHEADER_MAGIC 0x4A695444 | |
116 | #define JITHEADER_VERSION 1 | |
117 | ||
118 | struct jitheader { | |
119 | uint32_t magic; | |
120 | uint32_t version; | |
121 | uint32_t total_size; | |
122 | uint32_t elf_mach; | |
123 | uint32_t pad1; | |
124 | uint32_t pid; | |
125 | uint64_t timestamp; | |
126 | uint64_t flags; | |
127 | }; | |
128 | ||
129 | enum jit_record_type { | |
130 | JIT_CODE_LOAD = 0, | |
131 | JIT_CODE_DEBUG_INFO = 2, | |
132 | }; | |
133 | ||
134 | struct jr_prefix { | |
135 | uint32_t id; | |
136 | uint32_t total_size; | |
137 | uint64_t timestamp; | |
138 | }; | |
139 | ||
140 | struct jr_code_load { | |
141 | struct jr_prefix p; | |
142 | ||
143 | uint32_t pid; | |
144 | uint32_t tid; | |
145 | uint64_t vma; | |
146 | uint64_t code_addr; | |
147 | uint64_t code_size; | |
148 | uint64_t code_index; | |
149 | }; | |
150 | ||
151 | struct debug_entry { | |
152 | uint64_t addr; | |
153 | int lineno; | |
154 | int discrim; | |
155 | const char name[]; | |
156 | }; | |
157 | ||
158 | struct jr_code_debug_info { | |
159 | struct jr_prefix p; | |
160 | ||
161 | uint64_t code_addr; | |
162 | uint64_t nr_entry; | |
163 | struct debug_entry entries[]; | |
164 | }; | |
165 | ||
166 | static uint32_t get_e_machine(void) | |
167 | { | |
168 | Elf64_Ehdr elf_header; | |
169 | FILE *exe; | |
170 | size_t n; | |
171 | ||
172 | QEMU_BUILD_BUG_ON(offsetof(Elf32_Ehdr, e_machine) != | |
173 | offsetof(Elf64_Ehdr, e_machine)); | |
174 | ||
175 | exe = fopen("/proc/self/exe", "r"); | |
176 | if (exe == NULL) { | |
177 | return EM_NONE; | |
178 | } | |
179 | ||
180 | n = fread(&elf_header, sizeof(elf_header), 1, exe); | |
181 | fclose(exe); | |
182 | if (n != 1) { | |
183 | return EM_NONE; | |
184 | } | |
185 | ||
186 | return elf_header.e_machine; | |
187 | } | |
188 | ||
189 | void perf_enable_jitdump(void) | |
190 | { | |
191 | struct jitheader header; | |
192 | char jitdump_file[32]; | |
193 | void *perf_marker; | |
194 | ||
195 | if (!use_rt_clock) { | |
196 | warn_report("CLOCK_MONOTONIC is not available, proceeding without jitdump"); | |
197 | return; | |
198 | } | |
199 | ||
200 | snprintf(jitdump_file, sizeof(jitdump_file), "jit-%d.dump", getpid()); | |
201 | jitdump = safe_fopen_w(jitdump_file); | |
202 | if (jitdump == NULL) { | |
203 | warn_report("Could not open %s: %s, proceeding without jitdump", | |
204 | jitdump_file, strerror(errno)); | |
205 | return; | |
206 | } | |
207 | ||
208 | /* | |
209 | * `perf inject` will see that the mapped file name in the corresponding | |
210 | * PERF_RECORD_MMAP or PERF_RECORD_MMAP2 event is of the form jit-%d.dump | |
211 | * and will process it as a jitdump file. | |
212 | */ | |
213 | perf_marker = mmap(NULL, qemu_real_host_page_size(), PROT_READ | PROT_EXEC, | |
214 | MAP_PRIVATE, fileno(jitdump), 0); | |
215 | if (perf_marker == MAP_FAILED) { | |
216 | warn_report("Could not map %s: %s, proceeding without jitdump", | |
217 | jitdump_file, strerror(errno)); | |
218 | fclose(jitdump); | |
219 | jitdump = NULL; | |
220 | return; | |
221 | } | |
222 | ||
223 | header.magic = JITHEADER_MAGIC; | |
224 | header.version = JITHEADER_VERSION; | |
225 | header.total_size = sizeof(header); | |
226 | header.elf_mach = get_e_machine(); | |
227 | header.pad1 = 0; | |
228 | header.pid = getpid(); | |
229 | header.timestamp = get_clock(); | |
230 | header.flags = 0; | |
231 | fwrite(&header, sizeof(header), 1, jitdump); | |
232 | } | |
233 | ||
234 | void perf_report_prologue(const void *start, size_t size) | |
235 | { | |
236 | if (perfmap) { | |
237 | fprintf(perfmap, "%"PRIxPTR" %zx tcg-prologue-buffer\n", | |
238 | (uintptr_t)start, size); | |
239 | } | |
240 | } | |
241 | ||
242 | /* Write a JIT_CODE_DEBUG_INFO jitdump entry. */ | |
243 | static void write_jr_code_debug_info(const void *start, | |
244 | const struct debuginfo_query *q, | |
245 | size_t icount) | |
246 | { | |
247 | struct jr_code_debug_info rec; | |
248 | struct debug_entry ent; | |
249 | uintptr_t host_pc; | |
250 | int insn; | |
251 | ||
252 | /* Write the header. */ | |
253 | rec.p.id = JIT_CODE_DEBUG_INFO; | |
254 | rec.p.total_size = sizeof(rec) + sizeof(ent) + 1; | |
255 | rec.p.timestamp = get_clock(); | |
256 | rec.code_addr = (uintptr_t)start; | |
257 | rec.nr_entry = 1; | |
258 | for (insn = 0; insn < icount; insn++) { | |
259 | if (q[insn].file) { | |
260 | rec.p.total_size += sizeof(ent) + strlen(q[insn].file) + 1; | |
261 | rec.nr_entry++; | |
262 | } | |
263 | } | |
264 | fwrite(&rec, sizeof(rec), 1, jitdump); | |
265 | ||
266 | /* Write the main debug entries. */ | |
267 | for (insn = 0; insn < icount; insn++) { | |
268 | if (q[insn].file) { | |
269 | get_host_pc_size(&host_pc, NULL, start, insn); | |
270 | ent.addr = host_pc; | |
271 | ent.lineno = q[insn].line; | |
272 | ent.discrim = 0; | |
273 | fwrite(&ent, sizeof(ent), 1, jitdump); | |
274 | fwrite(q[insn].file, strlen(q[insn].file) + 1, 1, jitdump); | |
275 | } | |
276 | } | |
277 | ||
278 | /* Write the trailing debug_entry. */ | |
279 | ent.addr = (uintptr_t)start + tcg_ctx->gen_insn_end_off[icount - 1]; | |
280 | ent.lineno = 0; | |
281 | ent.discrim = 0; | |
282 | fwrite(&ent, sizeof(ent), 1, jitdump); | |
283 | fwrite("", 1, 1, jitdump); | |
284 | } | |
285 | ||
286 | /* Write a JIT_CODE_LOAD jitdump entry. */ | |
287 | static void write_jr_code_load(const void *start, uint16_t host_size, | |
288 | const struct debuginfo_query *q) | |
289 | { | |
290 | static uint64_t code_index; | |
291 | struct jr_code_load rec; | |
292 | const char *symbol; | |
293 | size_t symbol_size; | |
294 | ||
295 | symbol = pretty_symbol(q, &symbol_size); | |
296 | rec.p.id = JIT_CODE_LOAD; | |
297 | rec.p.total_size = sizeof(rec) + symbol_size + host_size; | |
298 | rec.p.timestamp = get_clock(); | |
299 | rec.pid = getpid(); | |
300 | rec.tid = qemu_get_thread_id(); | |
301 | rec.vma = (uintptr_t)start; | |
302 | rec.code_addr = (uintptr_t)start; | |
303 | rec.code_size = host_size; | |
304 | rec.code_index = code_index++; | |
305 | fwrite(&rec, sizeof(rec), 1, jitdump); | |
306 | fwrite(symbol, symbol_size, 1, jitdump); | |
307 | fwrite(start, host_size, 1, jitdump); | |
308 | } | |
309 | ||
310 | void perf_report_code(uint64_t guest_pc, TranslationBlock *tb, | |
311 | const void *start) | |
312 | { | |
313 | struct debuginfo_query *q; | |
314 | size_t insn; | |
315 | ||
316 | if (!perfmap && !jitdump) { | |
317 | return; | |
318 | } | |
319 | ||
320 | q = g_try_malloc0_n(tb->icount, sizeof(*q)); | |
321 | if (!q) { | |
322 | return; | |
323 | } | |
324 | ||
325 | debuginfo_lock(); | |
326 | ||
327 | /* Query debuginfo for each guest instruction. */ | |
328 | for (insn = 0; insn < tb->icount; insn++) { | |
329 | /* FIXME: This replicates the restore_state_to_opc() logic. */ | |
330 | q[insn].address = tcg_ctx->gen_insn_data[insn][0]; | |
331 | if (TARGET_TB_PCREL) { | |
332 | q[insn].address |= (guest_pc & TARGET_PAGE_MASK); | |
333 | } else { | |
334 | #if defined(TARGET_I386) | |
335 | q[insn].address -= tb->cs_base; | |
336 | #endif | |
337 | } | |
338 | q[insn].flags = DEBUGINFO_SYMBOL | (jitdump ? DEBUGINFO_LINE : 0); | |
339 | } | |
340 | debuginfo_query(q, tb->icount); | |
341 | ||
342 | /* Emit perfmap entries if needed. */ | |
343 | if (perfmap) { | |
344 | flockfile(perfmap); | |
345 | for (insn = 0; insn < tb->icount; insn++) { | |
346 | write_perfmap_entry(start, insn, &q[insn]); | |
347 | } | |
348 | funlockfile(perfmap); | |
349 | } | |
350 | ||
351 | /* Emit jitdump entries if needed. */ | |
352 | if (jitdump) { | |
353 | flockfile(jitdump); | |
354 | write_jr_code_debug_info(start, q, tb->icount); | |
355 | write_jr_code_load(start, tcg_ctx->gen_insn_end_off[tb->icount - 1], | |
356 | q); | |
357 | funlockfile(jitdump); | |
358 | } | |
359 | ||
360 | debuginfo_unlock(); | |
361 | g_free(q); | |
362 | } | |
363 | ||
364 | void perf_exit(void) | |
365 | { | |
366 | if (perfmap) { | |
367 | fclose(perfmap); | |
368 | perfmap = NULL; | |
369 | } | |
370 | ||
371 | if (jitdump) { | |
372 | fclose(jitdump); | |
373 | jitdump = NULL; | |
374 | } | |
375 | } |