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Linux/tools/perf/util/llvm-utils.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Copyright (C) 2015, Wang Nan <wangnan0@huawei.com>
  4  * Copyright (C) 2015, Huawei Inc.
  5  */
  6 
  7 #include <errno.h>
  8 #include <limits.h>
  9 #include <stdio.h>
 10 #include <stdlib.h>
 11 #include <linux/err.h>
 12 #include "debug.h"
 13 #include "llvm-utils.h"
 14 #include "config.h"
 15 #include "util.h"
 16 #include <sys/wait.h>
 17 #include <subcmd/exec-cmd.h>
 18 
 19 #define CLANG_BPF_CMD_DEFAULT_TEMPLATE                          \
 20                 "$CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS "\
 21                 "-DLINUX_VERSION_CODE=$LINUX_VERSION_CODE "     \
 22                 "$CLANG_OPTIONS $PERF_BPF_INC_OPTIONS $KERNEL_INC_OPTIONS " \
 23                 "-Wno-unused-value -Wno-pointer-sign "          \
 24                 "-working-directory $WORKING_DIR "              \
 25                 "-c \"$CLANG_SOURCE\" -target bpf $CLANG_EMIT_LLVM -O2 -o - $LLVM_OPTIONS_PIPE"
 26 
 27 struct llvm_param llvm_param = {
 28         .clang_path = "clang",
 29         .llc_path = "llc",
 30         .clang_bpf_cmd_template = CLANG_BPF_CMD_DEFAULT_TEMPLATE,
 31         .clang_opt = NULL,
 32         .opts = NULL,
 33         .kbuild_dir = NULL,
 34         .kbuild_opts = NULL,
 35         .user_set_param = false,
 36 };
 37 
 38 int perf_llvm_config(const char *var, const char *value)
 39 {
 40         if (!strstarts(var, "llvm."))
 41                 return 0;
 42         var += sizeof("llvm.") - 1;
 43 
 44         if (!strcmp(var, "clang-path"))
 45                 llvm_param.clang_path = strdup(value);
 46         else if (!strcmp(var, "clang-bpf-cmd-template"))
 47                 llvm_param.clang_bpf_cmd_template = strdup(value);
 48         else if (!strcmp(var, "clang-opt"))
 49                 llvm_param.clang_opt = strdup(value);
 50         else if (!strcmp(var, "kbuild-dir"))
 51                 llvm_param.kbuild_dir = strdup(value);
 52         else if (!strcmp(var, "kbuild-opts"))
 53                 llvm_param.kbuild_opts = strdup(value);
 54         else if (!strcmp(var, "dump-obj"))
 55                 llvm_param.dump_obj = !!perf_config_bool(var, value);
 56         else if (!strcmp(var, "opts"))
 57                 llvm_param.opts = strdup(value);
 58         else {
 59                 pr_debug("Invalid LLVM config option: %s\n", value);
 60                 return -1;
 61         }
 62         llvm_param.user_set_param = true;
 63         return 0;
 64 }
 65 
 66 static int
 67 search_program(const char *def, const char *name,
 68                char *output)
 69 {
 70         char *env, *path, *tmp = NULL;
 71         char buf[PATH_MAX];
 72         int ret;
 73 
 74         output[0] = '\0';
 75         if (def && def[0] != '\0') {
 76                 if (def[0] == '/') {
 77                         if (access(def, F_OK) == 0) {
 78                                 strlcpy(output, def, PATH_MAX);
 79                                 return 0;
 80                         }
 81                 } else if (def[0] != '\0')
 82                         name = def;
 83         }
 84 
 85         env = getenv("PATH");
 86         if (!env)
 87                 return -1;
 88         env = strdup(env);
 89         if (!env)
 90                 return -1;
 91 
 92         ret = -ENOENT;
 93         path = strtok_r(env, ":",  &tmp);
 94         while (path) {
 95                 scnprintf(buf, sizeof(buf), "%s/%s", path, name);
 96                 if (access(buf, F_OK) == 0) {
 97                         strlcpy(output, buf, PATH_MAX);
 98                         ret = 0;
 99                         break;
100                 }
101                 path = strtok_r(NULL, ":", &tmp);
102         }
103 
104         free(env);
105         return ret;
106 }
107 
108 #define READ_SIZE       4096
109 static int
110 read_from_pipe(const char *cmd, void **p_buf, size_t *p_read_sz)
111 {
112         int err = 0;
113         void *buf = NULL;
114         FILE *file = NULL;
115         size_t read_sz = 0, buf_sz = 0;
116         char serr[STRERR_BUFSIZE];
117 
118         file = popen(cmd, "r");
119         if (!file) {
120                 pr_err("ERROR: unable to popen cmd: %s\n",
121                        str_error_r(errno, serr, sizeof(serr)));
122                 return -EINVAL;
123         }
124 
125         while (!feof(file) && !ferror(file)) {
126                 /*
127                  * Make buf_sz always have obe byte extra space so we
128                  * can put '\0' there.
129                  */
130                 if (buf_sz - read_sz < READ_SIZE + 1) {
131                         void *new_buf;
132 
133                         buf_sz = read_sz + READ_SIZE + 1;
134                         new_buf = realloc(buf, buf_sz);
135 
136                         if (!new_buf) {
137                                 pr_err("ERROR: failed to realloc memory\n");
138                                 err = -ENOMEM;
139                                 goto errout;
140                         }
141 
142                         buf = new_buf;
143                 }
144                 read_sz += fread(buf + read_sz, 1, READ_SIZE, file);
145         }
146 
147         if (buf_sz - read_sz < 1) {
148                 pr_err("ERROR: internal error\n");
149                 err = -EINVAL;
150                 goto errout;
151         }
152 
153         if (ferror(file)) {
154                 pr_err("ERROR: error occurred when reading from pipe: %s\n",
155                        str_error_r(errno, serr, sizeof(serr)));
156                 err = -EIO;
157                 goto errout;
158         }
159 
160         err = WEXITSTATUS(pclose(file));
161         file = NULL;
162         if (err) {
163                 err = -EINVAL;
164                 goto errout;
165         }
166 
167         /*
168          * If buf is string, give it terminal '\0' to make our life
169          * easier. If buf is not string, that '\0' is out of space
170          * indicated by read_sz so caller won't even notice it.
171          */
172         ((char *)buf)[read_sz] = '\0';
173 
174         if (!p_buf)
175                 free(buf);
176         else
177                 *p_buf = buf;
178 
179         if (p_read_sz)
180                 *p_read_sz = read_sz;
181         return 0;
182 
183 errout:
184         if (file)
185                 pclose(file);
186         free(buf);
187         if (p_buf)
188                 *p_buf = NULL;
189         if (p_read_sz)
190                 *p_read_sz = 0;
191         return err;
192 }
193 
194 static inline void
195 force_set_env(const char *var, const char *value)
196 {
197         if (value) {
198                 setenv(var, value, 1);
199                 pr_debug("set env: %s=%s\n", var, value);
200         } else {
201                 unsetenv(var);
202                 pr_debug("unset env: %s\n", var);
203         }
204 }
205 
206 static void
207 version_notice(void)
208 {
209         pr_err(
210 "     \tLLVM 3.7 or newer is required. Which can be found from http://llvm.org\n"
211 "     \tYou may want to try git trunk:\n"
212 "     \t\tgit clone http://llvm.org/git/llvm.git\n"
213 "     \t\t     and\n"
214 "     \t\tgit clone http://llvm.org/git/clang.git\n\n"
215 "     \tOr fetch the latest clang/llvm 3.7 from pre-built llvm packages for\n"
216 "     \tdebian/ubuntu:\n"
217 "     \t\thttp://llvm.org/apt\n\n"
218 "     \tIf you are using old version of clang, change 'clang-bpf-cmd-template'\n"
219 "     \toption in [llvm] section of ~/.perfconfig to:\n\n"
220 "     \t  \"$CLANG_EXEC $CLANG_OPTIONS $KERNEL_INC_OPTIONS $PERF_BPF_INC_OPTIONS \\\n"
221 "     \t     -working-directory $WORKING_DIR -c $CLANG_SOURCE \\\n"
222 "     \t     -emit-llvm -o - | /path/to/llc -march=bpf -filetype=obj -o -\"\n"
223 "     \t(Replace /path/to/llc with path to your llc)\n\n"
224 );
225 }
226 
227 static int detect_kbuild_dir(char **kbuild_dir)
228 {
229         const char *test_dir = llvm_param.kbuild_dir;
230         const char *prefix_dir = "";
231         const char *suffix_dir = "";
232 
233         char *autoconf_path;
234 
235         int err;
236 
237         if (!test_dir) {
238                 /* _UTSNAME_LENGTH is 65 */
239                 char release[128];
240 
241                 err = fetch_kernel_version(NULL, release,
242                                            sizeof(release));
243                 if (err)
244                         return -EINVAL;
245 
246                 test_dir = release;
247                 prefix_dir = "/lib/modules/";
248                 suffix_dir = "/build";
249         }
250 
251         err = asprintf(&autoconf_path, "%s%s%s/include/generated/autoconf.h",
252                        prefix_dir, test_dir, suffix_dir);
253         if (err < 0)
254                 return -ENOMEM;
255 
256         if (access(autoconf_path, R_OK) == 0) {
257                 free(autoconf_path);
258 
259                 err = asprintf(kbuild_dir, "%s%s%s", prefix_dir, test_dir,
260                                suffix_dir);
261                 if (err < 0)
262                         return -ENOMEM;
263                 return 0;
264         }
265         free(autoconf_path);
266         return -ENOENT;
267 }
268 
269 static const char *kinc_fetch_script =
270 "#!/usr/bin/env sh\n"
271 "if ! test -d \"$KBUILD_DIR\"\n"
272 "then\n"
273 "       exit 1\n"
274 "fi\n"
275 "if ! test -f \"$KBUILD_DIR/include/generated/autoconf.h\"\n"
276 "then\n"
277 "       exit 1\n"
278 "fi\n"
279 "TMPDIR=`mktemp -d`\n"
280 "if test -z \"$TMPDIR\"\n"
281 "then\n"
282 "    exit 1\n"
283 "fi\n"
284 "cat << EOF > $TMPDIR/Makefile\n"
285 "obj-y := dummy.o\n"
286 "\\$(obj)/%.o: \\$(src)/%.c\n"
287 "\t@echo -n \"\\$(NOSTDINC_FLAGS) \\$(LINUXINCLUDE) \\$(EXTRA_CFLAGS)\"\n"
288 "EOF\n"
289 "touch $TMPDIR/dummy.c\n"
290 "make -s -C $KBUILD_DIR M=$TMPDIR $KBUILD_OPTS dummy.o 2>/dev/null\n"
291 "RET=$?\n"
292 "rm -rf $TMPDIR\n"
293 "exit $RET\n";
294 
295 void llvm__get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
296 {
297         static char *saved_kbuild_dir;
298         static char *saved_kbuild_include_opts;
299         int err;
300 
301         if (!kbuild_dir || !kbuild_include_opts)
302                 return;
303 
304         *kbuild_dir = NULL;
305         *kbuild_include_opts = NULL;
306 
307         if (saved_kbuild_dir && saved_kbuild_include_opts &&
308             !IS_ERR(saved_kbuild_dir) && !IS_ERR(saved_kbuild_include_opts)) {
309                 *kbuild_dir = strdup(saved_kbuild_dir);
310                 *kbuild_include_opts = strdup(saved_kbuild_include_opts);
311 
312                 if (*kbuild_dir && *kbuild_include_opts)
313                         return;
314 
315                 zfree(kbuild_dir);
316                 zfree(kbuild_include_opts);
317                 /*
318                  * Don't fall through: it may breaks saved_kbuild_dir and
319                  * saved_kbuild_include_opts if detect them again when
320                  * memory is low.
321                  */
322                 return;
323         }
324 
325         if (llvm_param.kbuild_dir && !llvm_param.kbuild_dir[0]) {
326                 pr_debug("[llvm.kbuild-dir] is set to \"\" deliberately.\n");
327                 pr_debug("Skip kbuild options detection.\n");
328                 goto errout;
329         }
330 
331         err = detect_kbuild_dir(kbuild_dir);
332         if (err) {
333                 pr_warning(
334 "WARNING:\tunable to get correct kernel building directory.\n"
335 "Hint:\tSet correct kbuild directory using 'kbuild-dir' option in [llvm]\n"
336 "     \tsection of ~/.perfconfig or set it to \"\" to suppress kbuild\n"
337 "     \tdetection.\n\n");
338                 goto errout;
339         }
340 
341         pr_debug("Kernel build dir is set to %s\n", *kbuild_dir);
342         force_set_env("KBUILD_DIR", *kbuild_dir);
343         force_set_env("KBUILD_OPTS", llvm_param.kbuild_opts);
344         err = read_from_pipe(kinc_fetch_script,
345                              (void **)kbuild_include_opts,
346                              NULL);
347         if (err) {
348                 pr_warning(
349 "WARNING:\tunable to get kernel include directories from '%s'\n"
350 "Hint:\tTry set clang include options using 'clang-bpf-cmd-template'\n"
351 "     \toption in [llvm] section of ~/.perfconfig and set 'kbuild-dir'\n"
352 "     \toption in [llvm] to \"\" to suppress this detection.\n\n",
353                         *kbuild_dir);
354 
355                 free(*kbuild_dir);
356                 *kbuild_dir = NULL;
357                 goto errout;
358         }
359 
360         pr_debug("include option is set to %s\n", *kbuild_include_opts);
361 
362         saved_kbuild_dir = strdup(*kbuild_dir);
363         saved_kbuild_include_opts = strdup(*kbuild_include_opts);
364 
365         if (!saved_kbuild_dir || !saved_kbuild_include_opts) {
366                 zfree(&saved_kbuild_dir);
367                 zfree(&saved_kbuild_include_opts);
368         }
369         return;
370 errout:
371         saved_kbuild_dir = ERR_PTR(-EINVAL);
372         saved_kbuild_include_opts = ERR_PTR(-EINVAL);
373 }
374 
375 int llvm__get_nr_cpus(void)
376 {
377         static int nr_cpus_avail = 0;
378         char serr[STRERR_BUFSIZE];
379 
380         if (nr_cpus_avail > 0)
381                 return nr_cpus_avail;
382 
383         nr_cpus_avail = sysconf(_SC_NPROCESSORS_CONF);
384         if (nr_cpus_avail <= 0) {
385                 pr_err(
386 "WARNING:\tunable to get available CPUs in this system: %s\n"
387 "        \tUse 128 instead.\n", str_error_r(errno, serr, sizeof(serr)));
388                 nr_cpus_avail = 128;
389         }
390         return nr_cpus_avail;
391 }
392 
393 void llvm__dump_obj(const char *path, void *obj_buf, size_t size)
394 {
395         char *obj_path = strdup(path);
396         FILE *fp;
397         char *p;
398 
399         if (!obj_path) {
400                 pr_warning("WARNING: Not enough memory, skip object dumping\n");
401                 return;
402         }
403 
404         p = strrchr(obj_path, '.');
405         if (!p || (strcmp(p, ".c") != 0)) {
406                 pr_warning("WARNING: invalid llvm source path: '%s', skip object dumping\n",
407                            obj_path);
408                 goto out;
409         }
410 
411         p[1] = 'o';
412         fp = fopen(obj_path, "wb");
413         if (!fp) {
414                 pr_warning("WARNING: failed to open '%s': %s, skip object dumping\n",
415                            obj_path, strerror(errno));
416                 goto out;
417         }
418 
419         pr_info("LLVM: dumping %s\n", obj_path);
420         if (fwrite(obj_buf, size, 1, fp) != 1)
421                 pr_warning("WARNING: failed to write to file '%s': %s, skip object dumping\n",
422                            obj_path, strerror(errno));
423         fclose(fp);
424 out:
425         free(obj_path);
426 }
427 
428 int llvm__compile_bpf(const char *path, void **p_obj_buf,
429                       size_t *p_obj_buf_sz)
430 {
431         size_t obj_buf_sz;
432         void *obj_buf = NULL;
433         int err, nr_cpus_avail;
434         unsigned int kernel_version;
435         char linux_version_code_str[64];
436         const char *clang_opt = llvm_param.clang_opt;
437         char clang_path[PATH_MAX], llc_path[PATH_MAX], abspath[PATH_MAX], nr_cpus_avail_str[64];
438         char serr[STRERR_BUFSIZE];
439         char *kbuild_dir = NULL, *kbuild_include_opts = NULL,
440              *perf_bpf_include_opts = NULL;
441         const char *template = llvm_param.clang_bpf_cmd_template;
442         char *pipe_template = NULL;
443         const char *opts = llvm_param.opts;
444         char *command_echo = NULL, *command_out;
445         char *perf_include_dir = system_path(PERF_INCLUDE_DIR);
446 
447         if (path[0] != '-' && realpath(path, abspath) == NULL) {
448                 err = errno;
449                 pr_err("ERROR: problems with path %s: %s\n",
450                        path, str_error_r(err, serr, sizeof(serr)));
451                 return -err;
452         }
453 
454         if (!template)
455                 template = CLANG_BPF_CMD_DEFAULT_TEMPLATE;
456 
457         err = search_program(llvm_param.clang_path,
458                              "clang", clang_path);
459         if (err) {
460                 pr_err(
461 "ERROR:\tunable to find clang.\n"
462 "Hint:\tTry to install latest clang/llvm to support BPF. Check your $PATH\n"
463 "     \tand 'clang-path' option in [llvm] section of ~/.perfconfig.\n");
464                 version_notice();
465                 return -ENOENT;
466         }
467 
468         /*
469          * This is an optional work. Even it fail we can continue our
470          * work. Needn't to check error return.
471          */
472         llvm__get_kbuild_opts(&kbuild_dir, &kbuild_include_opts);
473 
474         nr_cpus_avail = llvm__get_nr_cpus();
475         snprintf(nr_cpus_avail_str, sizeof(nr_cpus_avail_str), "%d",
476                  nr_cpus_avail);
477 
478         if (fetch_kernel_version(&kernel_version, NULL, 0))
479                 kernel_version = 0;
480 
481         snprintf(linux_version_code_str, sizeof(linux_version_code_str),
482                  "0x%x", kernel_version);
483         if (asprintf(&perf_bpf_include_opts, "-I%s/bpf", perf_include_dir) < 0)
484                 goto errout;
485         force_set_env("NR_CPUS", nr_cpus_avail_str);
486         force_set_env("LINUX_VERSION_CODE", linux_version_code_str);
487         force_set_env("CLANG_EXEC", clang_path);
488         force_set_env("CLANG_OPTIONS", clang_opt);
489         force_set_env("KERNEL_INC_OPTIONS", kbuild_include_opts);
490         force_set_env("PERF_BPF_INC_OPTIONS", perf_bpf_include_opts);
491         force_set_env("WORKING_DIR", kbuild_dir ? : ".");
492 
493         if (opts) {
494                 err = search_program(llvm_param.llc_path, "llc", llc_path);
495                 if (err) {
496                         pr_err("ERROR:\tunable to find llc.\n"
497                                "Hint:\tTry to install latest clang/llvm to support BPF. Check your $PATH\n"
498                                "     \tand 'llc-path' option in [llvm] section of ~/.perfconfig.\n");
499                         version_notice();
500                         goto errout;
501                 }
502 
503                 if (asprintf(&pipe_template, "%s -emit-llvm | %s -march=bpf %s -filetype=obj -o -",
504                               template, llc_path, opts) < 0) {
505                         pr_err("ERROR:\tnot enough memory to setup command line\n");
506                         goto errout;
507                 }
508 
509                 template = pipe_template;
510 
511         }
512 
513         /*
514          * Since we may reset clang's working dir, path of source file
515          * should be transferred into absolute path, except we want
516          * stdin to be source file (testing).
517          */
518         force_set_env("CLANG_SOURCE",
519                       (path[0] == '-') ? path : abspath);
520 
521         pr_debug("llvm compiling command template: %s\n", template);
522 
523         if (asprintf(&command_echo, "echo -n \"%s\"", template) < 0)
524                 goto errout;
525 
526         err = read_from_pipe(command_echo, (void **) &command_out, NULL);
527         if (err)
528                 goto errout;
529 
530         pr_debug("llvm compiling command : %s\n", command_out);
531 
532         err = read_from_pipe(template, &obj_buf, &obj_buf_sz);
533         if (err) {
534                 pr_err("ERROR:\tunable to compile %s\n", path);
535                 pr_err("Hint:\tCheck error message shown above.\n");
536                 pr_err("Hint:\tYou can also pre-compile it into .o using:\n");
537                 pr_err("     \t\tclang -target bpf -O2 -c %s\n", path);
538                 pr_err("     \twith proper -I and -D options.\n");
539                 goto errout;
540         }
541 
542         free(command_echo);
543         free(command_out);
544         free(kbuild_dir);
545         free(kbuild_include_opts);
546         free(perf_bpf_include_opts);
547         free(perf_include_dir);
548 
549         if (!p_obj_buf)
550                 free(obj_buf);
551         else
552                 *p_obj_buf = obj_buf;
553 
554         if (p_obj_buf_sz)
555                 *p_obj_buf_sz = obj_buf_sz;
556         return 0;
557 errout:
558         free(command_echo);
559         free(kbuild_dir);
560         free(kbuild_include_opts);
561         free(obj_buf);
562         free(perf_bpf_include_opts);
563         free(perf_include_dir);
564         free(pipe_template);
565         if (p_obj_buf)
566                 *p_obj_buf = NULL;
567         if (p_obj_buf_sz)
568                 *p_obj_buf_sz = 0;
569         return err;
570 }
571 
572 int llvm__search_clang(void)
573 {
574         char clang_path[PATH_MAX];
575 
576         return search_program(llvm_param.clang_path, "clang", clang_path);
577 }
578 

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