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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 <unistd.h>
 12 #include <linux/err.h>
 13 #include <linux/string.h>
 14 #include <linux/zalloc.h>
 15 #include "debug.h"
 16 #include "llvm-utils.h"
 17 #include "config.h"
 18 #include "util.h"
 19 #include <sys/wait.h>
 20 #include <subcmd/exec-cmd.h>
 21 
 22 #define CLANG_BPF_CMD_DEFAULT_TEMPLATE                          \
 23                 "$CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS "\
 24                 "-DLINUX_VERSION_CODE=$LINUX_VERSION_CODE "     \
 25                 "$CLANG_OPTIONS $PERF_BPF_INC_OPTIONS $KERNEL_INC_OPTIONS " \
 26                 "-Wno-unused-value -Wno-pointer-sign "          \
 27                 "-working-directory $WORKING_DIR "              \
 28                 "-c \"$CLANG_SOURCE\" -target bpf $CLANG_EMIT_LLVM -O2 -o - $LLVM_OPTIONS_PIPE"
 29 
 30 struct llvm_param llvm_param = {
 31         .clang_path = "clang",
 32         .llc_path = "llc",
 33         .clang_bpf_cmd_template = CLANG_BPF_CMD_DEFAULT_TEMPLATE,
 34         .clang_opt = NULL,
 35         .opts = NULL,
 36         .kbuild_dir = NULL,
 37         .kbuild_opts = NULL,
 38         .user_set_param = false,
 39 };
 40 
 41 int perf_llvm_config(const char *var, const char *value)
 42 {
 43         if (!strstarts(var, "llvm."))
 44                 return 0;
 45         var += sizeof("llvm.") - 1;
 46 
 47         if (!strcmp(var, "clang-path"))
 48                 llvm_param.clang_path = strdup(value);
 49         else if (!strcmp(var, "clang-bpf-cmd-template"))
 50                 llvm_param.clang_bpf_cmd_template = strdup(value);
 51         else if (!strcmp(var, "clang-opt"))
 52                 llvm_param.clang_opt = strdup(value);
 53         else if (!strcmp(var, "kbuild-dir"))
 54                 llvm_param.kbuild_dir = strdup(value);
 55         else if (!strcmp(var, "kbuild-opts"))
 56                 llvm_param.kbuild_opts = strdup(value);
 57         else if (!strcmp(var, "dump-obj"))
 58                 llvm_param.dump_obj = !!perf_config_bool(var, value);
 59         else if (!strcmp(var, "opts"))
 60                 llvm_param.opts = strdup(value);
 61         else {
 62                 pr_debug("Invalid LLVM config option: %s\n", value);
 63                 return -1;
 64         }
 65         llvm_param.user_set_param = true;
 66         return 0;
 67 }
 68 
 69 static int
 70 search_program(const char *def, const char *name,
 71                char *output)
 72 {
 73         char *env, *path, *tmp = NULL;
 74         char buf[PATH_MAX];
 75         int ret;
 76 
 77         output[0] = '\0';
 78         if (def && def[0] != '\0') {
 79                 if (def[0] == '/') {
 80                         if (access(def, F_OK) == 0) {
 81                                 strlcpy(output, def, PATH_MAX);
 82                                 return 0;
 83                         }
 84                 } else if (def[0] != '\0')
 85                         name = def;
 86         }
 87 
 88         env = getenv("PATH");
 89         if (!env)
 90                 return -1;
 91         env = strdup(env);
 92         if (!env)
 93                 return -1;
 94 
 95         ret = -ENOENT;
 96         path = strtok_r(env, ":",  &tmp);
 97         while (path) {
 98                 scnprintf(buf, sizeof(buf), "%s/%s", path, name);
 99                 if (access(buf, F_OK) == 0) {
100                         strlcpy(output, buf, PATH_MAX);
101                         ret = 0;
102                         break;
103                 }
104                 path = strtok_r(NULL, ":", &tmp);
105         }
106 
107         free(env);
108         return ret;
109 }
110 
111 #define READ_SIZE       4096
112 static int
113 read_from_pipe(const char *cmd, void **p_buf, size_t *p_read_sz)
114 {
115         int err = 0;
116         void *buf = NULL;
117         FILE *file = NULL;
118         size_t read_sz = 0, buf_sz = 0;
119         char serr[STRERR_BUFSIZE];
120 
121         file = popen(cmd, "r");
122         if (!file) {
123                 pr_err("ERROR: unable to popen cmd: %s\n",
124                        str_error_r(errno, serr, sizeof(serr)));
125                 return -EINVAL;
126         }
127 
128         while (!feof(file) && !ferror(file)) {
129                 /*
130                  * Make buf_sz always have obe byte extra space so we
131                  * can put '\0' there.
132                  */
133                 if (buf_sz - read_sz < READ_SIZE + 1) {
134                         void *new_buf;
135 
136                         buf_sz = read_sz + READ_SIZE + 1;
137                         new_buf = realloc(buf, buf_sz);
138 
139                         if (!new_buf) {
140                                 pr_err("ERROR: failed to realloc memory\n");
141                                 err = -ENOMEM;
142                                 goto errout;
143                         }
144 
145                         buf = new_buf;
146                 }
147                 read_sz += fread(buf + read_sz, 1, READ_SIZE, file);
148         }
149 
150         if (buf_sz - read_sz < 1) {
151                 pr_err("ERROR: internal error\n");
152                 err = -EINVAL;
153                 goto errout;
154         }
155 
156         if (ferror(file)) {
157                 pr_err("ERROR: error occurred when reading from pipe: %s\n",
158                        str_error_r(errno, serr, sizeof(serr)));
159                 err = -EIO;
160                 goto errout;
161         }
162 
163         err = WEXITSTATUS(pclose(file));
164         file = NULL;
165         if (err) {
166                 err = -EINVAL;
167                 goto errout;
168         }
169 
170         /*
171          * If buf is string, give it terminal '\0' to make our life
172          * easier. If buf is not string, that '\0' is out of space
173          * indicated by read_sz so caller won't even notice it.
174          */
175         ((char *)buf)[read_sz] = '\0';
176 
177         if (!p_buf)
178                 free(buf);
179         else
180                 *p_buf = buf;
181 
182         if (p_read_sz)
183                 *p_read_sz = read_sz;
184         return 0;
185 
186 errout:
187         if (file)
188                 pclose(file);
189         free(buf);
190         if (p_buf)
191                 *p_buf = NULL;
192         if (p_read_sz)
193                 *p_read_sz = 0;
194         return err;
195 }
196 
197 static inline void
198 force_set_env(const char *var, const char *value)
199 {
200         if (value) {
201                 setenv(var, value, 1);
202                 pr_debug("set env: %s=%s\n", var, value);
203         } else {
204                 unsetenv(var);
205                 pr_debug("unset env: %s\n", var);
206         }
207 }
208 
209 static void
210 version_notice(void)
211 {
212         pr_err(
213 "     \tLLVM 3.7 or newer is required. Which can be found from http://llvm.org\n"
214 "     \tYou may want to try git trunk:\n"
215 "     \t\tgit clone http://llvm.org/git/llvm.git\n"
216 "     \t\t     and\n"
217 "     \t\tgit clone http://llvm.org/git/clang.git\n\n"
218 "     \tOr fetch the latest clang/llvm 3.7 from pre-built llvm packages for\n"
219 "     \tdebian/ubuntu:\n"
220 "     \t\thttp://llvm.org/apt\n\n"
221 "     \tIf you are using old version of clang, change 'clang-bpf-cmd-template'\n"
222 "     \toption in [llvm] section of ~/.perfconfig to:\n\n"
223 "     \t  \"$CLANG_EXEC $CLANG_OPTIONS $KERNEL_INC_OPTIONS $PERF_BPF_INC_OPTIONS \\\n"
224 "     \t     -working-directory $WORKING_DIR -c $CLANG_SOURCE \\\n"
225 "     \t     -emit-llvm -o - | /path/to/llc -march=bpf -filetype=obj -o -\"\n"
226 "     \t(Replace /path/to/llc with path to your llc)\n\n"
227 );
228 }
229 
230 static int detect_kbuild_dir(char **kbuild_dir)
231 {
232         const char *test_dir = llvm_param.kbuild_dir;
233         const char *prefix_dir = "";
234         const char *suffix_dir = "";
235 
236         /* _UTSNAME_LENGTH is 65 */
237         char release[128];
238 
239         char *autoconf_path;
240 
241         int err;
242 
243         if (!test_dir) {
244                 err = fetch_kernel_version(NULL, release,
245                                            sizeof(release));
246                 if (err)
247                         return -EINVAL;
248 
249                 test_dir = release;
250                 prefix_dir = "/lib/modules/";
251                 suffix_dir = "/build";
252         }
253 
254         err = asprintf(&autoconf_path, "%s%s%s/include/generated/autoconf.h",
255                        prefix_dir, test_dir, suffix_dir);
256         if (err < 0)
257                 return -ENOMEM;
258 
259         if (access(autoconf_path, R_OK) == 0) {
260                 free(autoconf_path);
261 
262                 err = asprintf(kbuild_dir, "%s%s%s", prefix_dir, test_dir,
263                                suffix_dir);
264                 if (err < 0)
265                         return -ENOMEM;
266                 return 0;
267         }
268         pr_debug("%s: Couldn't find \"%s\", missing kernel-devel package?.\n",
269                  __func__, autoconf_path);
270         free(autoconf_path);
271         return -ENOENT;
272 }
273 
274 static const char *kinc_fetch_script =
275 "#!/usr/bin/env sh\n"
276 "if ! test -d \"$KBUILD_DIR\"\n"
277 "then\n"
278 "       exit 1\n"
279 "fi\n"
280 "if ! test -f \"$KBUILD_DIR/include/generated/autoconf.h\"\n"
281 "then\n"
282 "       exit 1\n"
283 "fi\n"
284 "TMPDIR=`mktemp -d`\n"
285 "if test -z \"$TMPDIR\"\n"
286 "then\n"
287 "    exit 1\n"
288 "fi\n"
289 "cat << EOF > $TMPDIR/Makefile\n"
290 "obj-y := dummy.o\n"
291 "\\$(obj)/%.o: \\$(src)/%.c\n"
292 "\t@echo -n \"\\$(NOSTDINC_FLAGS) \\$(LINUXINCLUDE) \\$(EXTRA_CFLAGS)\"\n"
293 "\t\\$(CC) -c -o \\$@ \\$<\n"
294 "EOF\n"
295 "touch $TMPDIR/dummy.c\n"
296 "make -s -C $KBUILD_DIR M=$TMPDIR $KBUILD_OPTS dummy.o 2>/dev/null\n"
297 "RET=$?\n"
298 "rm -rf $TMPDIR\n"
299 "exit $RET\n";
300 
301 void llvm__get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
302 {
303         static char *saved_kbuild_dir;
304         static char *saved_kbuild_include_opts;
305         int err;
306 
307         if (!kbuild_dir || !kbuild_include_opts)
308                 return;
309 
310         *kbuild_dir = NULL;
311         *kbuild_include_opts = NULL;
312 
313         if (saved_kbuild_dir && saved_kbuild_include_opts &&
314             !IS_ERR(saved_kbuild_dir) && !IS_ERR(saved_kbuild_include_opts)) {
315                 *kbuild_dir = strdup(saved_kbuild_dir);
316                 *kbuild_include_opts = strdup(saved_kbuild_include_opts);
317 
318                 if (*kbuild_dir && *kbuild_include_opts)
319                         return;
320 
321                 zfree(kbuild_dir);
322                 zfree(kbuild_include_opts);
323                 /*
324                  * Don't fall through: it may breaks saved_kbuild_dir and
325                  * saved_kbuild_include_opts if detect them again when
326                  * memory is low.
327                  */
328                 return;
329         }
330 
331         if (llvm_param.kbuild_dir && !llvm_param.kbuild_dir[0]) {
332                 pr_debug("[llvm.kbuild-dir] is set to \"\" deliberately.\n");
333                 pr_debug("Skip kbuild options detection.\n");
334                 goto errout;
335         }
336 
337         err = detect_kbuild_dir(kbuild_dir);
338         if (err) {
339                 pr_warning(
340 "WARNING:\tunable to get correct kernel building directory.\n"
341 "Hint:\tSet correct kbuild directory using 'kbuild-dir' option in [llvm]\n"
342 "     \tsection of ~/.perfconfig or set it to \"\" to suppress kbuild\n"
343 "     \tdetection.\n\n");
344                 goto errout;
345         }
346 
347         pr_debug("Kernel build dir is set to %s\n", *kbuild_dir);
348         force_set_env("KBUILD_DIR", *kbuild_dir);
349         force_set_env("KBUILD_OPTS", llvm_param.kbuild_opts);
350         err = read_from_pipe(kinc_fetch_script,
351                              (void **)kbuild_include_opts,
352                              NULL);
353         if (err) {
354                 pr_warning(
355 "WARNING:\tunable to get kernel include directories from '%s'\n"
356 "Hint:\tTry set clang include options using 'clang-bpf-cmd-template'\n"
357 "     \toption in [llvm] section of ~/.perfconfig and set 'kbuild-dir'\n"
358 "     \toption in [llvm] to \"\" to suppress this detection.\n\n",
359                         *kbuild_dir);
360 
361                 zfree(kbuild_dir);
362                 goto errout;
363         }
364 
365         pr_debug("include option is set to %s\n", *kbuild_include_opts);
366 
367         saved_kbuild_dir = strdup(*kbuild_dir);
368         saved_kbuild_include_opts = strdup(*kbuild_include_opts);
369 
370         if (!saved_kbuild_dir || !saved_kbuild_include_opts) {
371                 zfree(&saved_kbuild_dir);
372                 zfree(&saved_kbuild_include_opts);
373         }
374         return;
375 errout:
376         saved_kbuild_dir = ERR_PTR(-EINVAL);
377         saved_kbuild_include_opts = ERR_PTR(-EINVAL);
378 }
379 
380 int llvm__get_nr_cpus(void)
381 {
382         static int nr_cpus_avail = 0;
383         char serr[STRERR_BUFSIZE];
384 
385         if (nr_cpus_avail > 0)
386                 return nr_cpus_avail;
387 
388         nr_cpus_avail = sysconf(_SC_NPROCESSORS_CONF);
389         if (nr_cpus_avail <= 0) {
390                 pr_err(
391 "WARNING:\tunable to get available CPUs in this system: %s\n"
392 "        \tUse 128 instead.\n", str_error_r(errno, serr, sizeof(serr)));
393                 nr_cpus_avail = 128;
394         }
395         return nr_cpus_avail;
396 }
397 
398 void llvm__dump_obj(const char *path, void *obj_buf, size_t size)
399 {
400         char *obj_path = strdup(path);
401         FILE *fp;
402         char *p;
403 
404         if (!obj_path) {
405                 pr_warning("WARNING: Not enough memory, skip object dumping\n");
406                 return;
407         }
408 
409         p = strrchr(obj_path, '.');
410         if (!p || (strcmp(p, ".c") != 0)) {
411                 pr_warning("WARNING: invalid llvm source path: '%s', skip object dumping\n",
412                            obj_path);
413                 goto out;
414         }
415 
416         p[1] = 'o';
417         fp = fopen(obj_path, "wb");
418         if (!fp) {
419                 pr_warning("WARNING: failed to open '%s': %s, skip object dumping\n",
420                            obj_path, strerror(errno));
421                 goto out;
422         }
423 
424         pr_debug("LLVM: dumping %s\n", obj_path);
425         if (fwrite(obj_buf, size, 1, fp) != 1)
426                 pr_debug("WARNING: failed to write to file '%s': %s, skip object dumping\n", obj_path, strerror(errno));
427         fclose(fp);
428 out:
429         free(obj_path);
430 }
431 
432 int llvm__compile_bpf(const char *path, void **p_obj_buf,
433                       size_t *p_obj_buf_sz)
434 {
435         size_t obj_buf_sz;
436         void *obj_buf = NULL;
437         int err, nr_cpus_avail;
438         unsigned int kernel_version;
439         char linux_version_code_str[64];
440         const char *clang_opt = llvm_param.clang_opt;
441         char clang_path[PATH_MAX], llc_path[PATH_MAX], abspath[PATH_MAX], nr_cpus_avail_str[64];
442         char serr[STRERR_BUFSIZE];
443         char *kbuild_dir = NULL, *kbuild_include_opts = NULL,
444              *perf_bpf_include_opts = NULL;
445         const char *template = llvm_param.clang_bpf_cmd_template;
446         char *pipe_template = NULL;
447         const char *opts = llvm_param.opts;
448         char *command_echo = NULL, *command_out;
449         char *perf_include_dir = system_path(PERF_INCLUDE_DIR);
450 
451         if (path[0] != '-' && realpath(path, abspath) == NULL) {
452                 err = errno;
453                 pr_err("ERROR: problems with path %s: %s\n",
454                        path, str_error_r(err, serr, sizeof(serr)));
455                 return -err;
456         }
457 
458         if (!template)
459                 template = CLANG_BPF_CMD_DEFAULT_TEMPLATE;
460 
461         err = search_program(llvm_param.clang_path,
462                              "clang", clang_path);
463         if (err) {
464                 pr_err(
465 "ERROR:\tunable to find clang.\n"
466 "Hint:\tTry to install latest clang/llvm to support BPF. Check your $PATH\n"
467 "     \tand 'clang-path' option in [llvm] section of ~/.perfconfig.\n");
468                 version_notice();
469                 return -ENOENT;
470         }
471 
472         /*
473          * This is an optional work. Even it fail we can continue our
474          * work. Needn't check error return.
475          */
476         llvm__get_kbuild_opts(&kbuild_dir, &kbuild_include_opts);
477 
478         nr_cpus_avail = llvm__get_nr_cpus();
479         snprintf(nr_cpus_avail_str, sizeof(nr_cpus_avail_str), "%d",
480                  nr_cpus_avail);
481 
482         if (fetch_kernel_version(&kernel_version, NULL, 0))
483                 kernel_version = 0;
484 
485         snprintf(linux_version_code_str, sizeof(linux_version_code_str),
486                  "0x%x", kernel_version);
487         if (asprintf(&perf_bpf_include_opts, "-I%s/bpf", perf_include_dir) < 0)
488                 goto errout;
489         force_set_env("NR_CPUS", nr_cpus_avail_str);
490         force_set_env("LINUX_VERSION_CODE", linux_version_code_str);
491         force_set_env("CLANG_EXEC", clang_path);
492         force_set_env("CLANG_OPTIONS", clang_opt);
493         force_set_env("KERNEL_INC_OPTIONS", kbuild_include_opts);
494         force_set_env("PERF_BPF_INC_OPTIONS", perf_bpf_include_opts);
495         force_set_env("WORKING_DIR", kbuild_dir ? : ".");
496 
497         if (opts) {
498                 err = search_program(llvm_param.llc_path, "llc", llc_path);
499                 if (err) {
500                         pr_err("ERROR:\tunable to find llc.\n"
501                                "Hint:\tTry to install latest clang/llvm to support BPF. Check your $PATH\n"
502                                "     \tand 'llc-path' option in [llvm] section of ~/.perfconfig.\n");
503                         version_notice();
504                         goto errout;
505                 }
506 
507                 if (asprintf(&pipe_template, "%s -emit-llvm | %s -march=bpf %s -filetype=obj -o -",
508                               template, llc_path, opts) < 0) {
509                         pr_err("ERROR:\tnot enough memory to setup command line\n");
510                         goto errout;
511                 }
512 
513                 template = pipe_template;
514 
515         }
516 
517         /*
518          * Since we may reset clang's working dir, path of source file
519          * should be transferred into absolute path, except we want
520          * stdin to be source file (testing).
521          */
522         force_set_env("CLANG_SOURCE",
523                       (path[0] == '-') ? path : abspath);
524 
525         pr_debug("llvm compiling command template: %s\n", template);
526 
527         if (asprintf(&command_echo, "echo -n \"%s\"", template) < 0)
528                 goto errout;
529 
530         err = read_from_pipe(command_echo, (void **) &command_out, NULL);
531         if (err)
532                 goto errout;
533 
534         pr_debug("llvm compiling command : %s\n", command_out);
535 
536         err = read_from_pipe(template, &obj_buf, &obj_buf_sz);
537         if (err) {
538                 pr_err("ERROR:\tunable to compile %s\n", path);
539                 pr_err("Hint:\tCheck error message shown above.\n");
540                 pr_err("Hint:\tYou can also pre-compile it into .o using:\n");
541                 pr_err("     \t\tclang -target bpf -O2 -c %s\n", path);
542                 pr_err("     \twith proper -I and -D options.\n");
543                 goto errout;
544         }
545 
546         free(command_echo);
547         free(command_out);
548         free(kbuild_dir);
549         free(kbuild_include_opts);
550         free(perf_bpf_include_opts);
551         free(perf_include_dir);
552 
553         if (!p_obj_buf)
554                 free(obj_buf);
555         else
556                 *p_obj_buf = obj_buf;
557 
558         if (p_obj_buf_sz)
559                 *p_obj_buf_sz = obj_buf_sz;
560         return 0;
561 errout:
562         free(command_echo);
563         free(kbuild_dir);
564         free(kbuild_include_opts);
565         free(obj_buf);
566         free(perf_bpf_include_opts);
567         free(perf_include_dir);
568         free(pipe_template);
569         if (p_obj_buf)
570                 *p_obj_buf = NULL;
571         if (p_obj_buf_sz)
572                 *p_obj_buf_sz = 0;
573         return err;
574 }
575 
576 int llvm__search_clang(void)
577 {
578         char clang_path[PATH_MAX];
579 
580         return search_program(llvm_param.clang_path, "clang", clang_path);
581 }
582 

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