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

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

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