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

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