Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
/*
 * Copyright (C) 2015, Wang Nan <wangnan0@huawei.com>
 * Copyright (C) 2015, Huawei Inc.
 */

#include <stdio.h>
#include "util.h"
#include "debug.h"
#include "llvm-utils.h"
#include "cache.h"

#define CLANG_BPF_CMD_DEFAULT_TEMPLATE				\
		"$CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS "\
		"-DLINUX_VERSION_CODE=$LINUX_VERSION_CODE "	\
		"$CLANG_OPTIONS $KERNEL_INC_OPTIONS "		\
		"-Wno-unused-value -Wno-pointer-sign "		\
		"-working-directory $WORKING_DIR "		\
		"-c \"$CLANG_SOURCE\" -target bpf -O2 -o -"

struct llvm_param llvm_param = {
	.clang_path = "clang",
	.clang_bpf_cmd_template = CLANG_BPF_CMD_DEFAULT_TEMPLATE,
	.clang_opt = NULL,
	.kbuild_dir = NULL,
	.kbuild_opts = NULL,
	.user_set_param = false,
};

int perf_llvm_config(const char *var, const char *value)
{
	if (prefixcmp(var, "llvm."))
		return 0;
	var += sizeof("llvm.") - 1;

	if (!strcmp(var, "clang-path"))
		llvm_param.clang_path = strdup(value);
	else if (!strcmp(var, "clang-bpf-cmd-template"))
		llvm_param.clang_bpf_cmd_template = strdup(value);
	else if (!strcmp(var, "clang-opt"))
		llvm_param.clang_opt = strdup(value);
	else if (!strcmp(var, "kbuild-dir"))
		llvm_param.kbuild_dir = strdup(value);
	else if (!strcmp(var, "kbuild-opts"))
		llvm_param.kbuild_opts = strdup(value);
	else
		return -1;
	llvm_param.user_set_param = true;
	return 0;
}

static int
search_program(const char *def, const char *name,
	       char *output)
{
	char *env, *path, *tmp = NULL;
	char buf[PATH_MAX];
	int ret;

	output[0] = '\0';
	if (def && def[0] != '\0') {
		if (def[0] == '/') {
			if (access(def, F_OK) == 0) {
				strlcpy(output, def, PATH_MAX);
				return 0;
			}
		} else if (def[0] != '\0')
			name = def;
	}

	env = getenv("PATH");
	if (!env)
		return -1;
	env = strdup(env);
	if (!env)
		return -1;

	ret = -ENOENT;
	path = strtok_r(env, ":",  &tmp);
	while (path) {
		scnprintf(buf, sizeof(buf), "%s/%s", path, name);
		if (access(buf, F_OK) == 0) {
			strlcpy(output, buf, PATH_MAX);
			ret = 0;
			break;
		}
		path = strtok_r(NULL, ":", &tmp);
	}

	free(env);
	return ret;
}

#define READ_SIZE	4096
static int
read_from_pipe(const char *cmd, void **p_buf, size_t *p_read_sz)
{
	int err = 0;
	void *buf = NULL;
	FILE *file = NULL;
	size_t read_sz = 0, buf_sz = 0;

	file = popen(cmd, "r");
	if (!file) {
		pr_err("ERROR: unable to popen cmd: %s\n",
		       strerror(errno));
		return -EINVAL;
	}

	while (!feof(file) && !ferror(file)) {
		/*
		 * Make buf_sz always have obe byte extra space so we
		 * can put '\0' there.
		 */
		if (buf_sz - read_sz < READ_SIZE + 1) {
			void *new_buf;

			buf_sz = read_sz + READ_SIZE + 1;
			new_buf = realloc(buf, buf_sz);

			if (!new_buf) {
				pr_err("ERROR: failed to realloc memory\n");
				err = -ENOMEM;
				goto errout;
			}

			buf = new_buf;
		}
		read_sz += fread(buf + read_sz, 1, READ_SIZE, file);
	}

	if (buf_sz - read_sz < 1) {
		pr_err("ERROR: internal error\n");
		err = -EINVAL;
		goto errout;
	}

	if (ferror(file)) {
		pr_err("ERROR: error occurred when reading from pipe: %s\n",
		       strerror(errno));
		err = -EIO;
		goto errout;
	}

	err = WEXITSTATUS(pclose(file));
	file = NULL;
	if (err) {
		err = -EINVAL;
		goto errout;
	}

	/*
	 * If buf is string, give it terminal '\0' to make our life
	 * easier. If buf is not string, that '\0' is out of space
	 * indicated by read_sz so caller won't even notice it.
	 */
	((char *)buf)[read_sz] = '\0';

	if (!p_buf)
		free(buf);
	else
		*p_buf = buf;

	if (p_read_sz)
		*p_read_sz = read_sz;
	return 0;

errout:
	if (file)
		pclose(file);
	free(buf);
	if (p_buf)
		*p_buf = NULL;
	if (p_read_sz)
		*p_read_sz = 0;
	return err;
}

static inline void
force_set_env(const char *var, const char *value)
{
	if (value) {
		setenv(var, value, 1);
		pr_debug("set env: %s=%s\n", var, value);
	} else {
		unsetenv(var);
		pr_debug("unset env: %s\n", var);
	}
}

static void
version_notice(void)
{
	pr_err(
"     \tLLVM 3.7 or newer is required. Which can be found from http://llvm.org\n"
"     \tYou may want to try git trunk:\n"
"     \t\tgit clone http://llvm.org/git/llvm.git\n"
"     \t\t     and\n"
"     \t\tgit clone http://llvm.org/git/clang.git\n\n"
"     \tOr fetch the latest clang/llvm 3.7 from pre-built llvm packages for\n"
"     \tdebian/ubuntu:\n"
"     \t\thttp://llvm.org/apt\n\n"
"     \tIf you are using old version of clang, change 'clang-bpf-cmd-template'\n"
"     \toption in [llvm] section of ~/.perfconfig to:\n\n"
"     \t  \"$CLANG_EXEC $CLANG_OPTIONS $KERNEL_INC_OPTIONS \\\n"
"     \t     -working-directory $WORKING_DIR -c $CLANG_SOURCE \\\n"
"     \t     -emit-llvm -o - | /path/to/llc -march=bpf -filetype=obj -o -\"\n"
"     \t(Replace /path/to/llc with path to your llc)\n\n"
);
}

static int detect_kbuild_dir(char **kbuild_dir)
{
	const char *test_dir = llvm_param.kbuild_dir;
	const char *prefix_dir = "";
	const char *suffix_dir = "";

	char *autoconf_path;

	int err;

	if (!test_dir) {
		/* _UTSNAME_LENGTH is 65 */
		char release[128];

		err = fetch_kernel_version(NULL, release,
					   sizeof(release));
		if (err)
			return -EINVAL;

		test_dir = release;
		prefix_dir = "/lib/modules/";
		suffix_dir = "/build";
	}

	err = asprintf(&autoconf_path, "%s%s%s/include/generated/autoconf.h",
		       prefix_dir, test_dir, suffix_dir);
	if (err < 0)
		return -ENOMEM;

	if (access(autoconf_path, R_OK) == 0) {
		free(autoconf_path);

		err = asprintf(kbuild_dir, "%s%s%s", prefix_dir, test_dir,
			       suffix_dir);
		if (err < 0)
			return -ENOMEM;
		return 0;
	}
	free(autoconf_path);
	return -ENOENT;
}

static const char *kinc_fetch_script =
"#!/usr/bin/env sh\n"
"if ! test -d \"$KBUILD_DIR\"\n"
"then\n"
"	exit -1\n"
"fi\n"
"if ! test -f \"$KBUILD_DIR/include/generated/autoconf.h\"\n"
"then\n"
"	exit -1\n"
"fi\n"
"TMPDIR=`mktemp -d`\n"
"if test -z \"$TMPDIR\"\n"
"then\n"
"    exit -1\n"
"fi\n"
"cat << EOF > $TMPDIR/Makefile\n"
"obj-y := dummy.o\n"
"\\$(obj)/%.o: \\$(src)/%.c\n"
"\t@echo -n \"\\$(NOSTDINC_FLAGS) \\$(LINUXINCLUDE) \\$(EXTRA_CFLAGS)\"\n"
"EOF\n"
"touch $TMPDIR/dummy.c\n"
"make -s -C $KBUILD_DIR M=$TMPDIR $KBUILD_OPTS dummy.o 2>/dev/null\n"
"RET=$?\n"
"rm -rf $TMPDIR\n"
"exit $RET\n";

static inline void
get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
{
	int err;

	if (!kbuild_dir || !kbuild_include_opts)
		return;

	*kbuild_dir = NULL;
	*kbuild_include_opts = NULL;

	if (llvm_param.kbuild_dir && !llvm_param.kbuild_dir[0]) {
		pr_debug("[llvm.kbuild-dir] is set to \"\" deliberately.\n");
		pr_debug("Skip kbuild options detection.\n");
		return;
	}

	err = detect_kbuild_dir(kbuild_dir);
	if (err) {
		pr_warning(
"WARNING:\tunable to get correct kernel building directory.\n"
"Hint:\tSet correct kbuild directory using 'kbuild-dir' option in [llvm]\n"
"     \tsection of ~/.perfconfig or set it to \"\" to suppress kbuild\n"
"     \tdetection.\n\n");
		return;
	}

	pr_debug("Kernel build dir is set to %s\n", *kbuild_dir);
	force_set_env("KBUILD_DIR", *kbuild_dir);
	force_set_env("KBUILD_OPTS", llvm_param.kbuild_opts);
	err = read_from_pipe(kinc_fetch_script,
			     (void **)kbuild_include_opts,
			     NULL);
	if (err) {
		pr_warning(
"WARNING:\tunable to get kernel include directories from '%s'\n"
"Hint:\tTry set clang include options using 'clang-bpf-cmd-template'\n"
"     \toption in [llvm] section of ~/.perfconfig and set 'kbuild-dir'\n"
"     \toption in [llvm] to \"\" to suppress this detection.\n\n",
			*kbuild_dir);

		free(*kbuild_dir);
		*kbuild_dir = NULL;
		return;
	}

	pr_debug("include option is set to %s\n", *kbuild_include_opts);
}

int llvm__compile_bpf(const char *path, void **p_obj_buf,
		      size_t *p_obj_buf_sz)
{
	size_t obj_buf_sz;
	void *obj_buf = NULL;
	int err, nr_cpus_avail;
	unsigned int kernel_version;
	char linux_version_code_str[64];
	const char *clang_opt = llvm_param.clang_opt;
	char clang_path[PATH_MAX], nr_cpus_avail_str[64];
	char *kbuild_dir = NULL, *kbuild_include_opts = NULL;
	const char *template = llvm_param.clang_bpf_cmd_template;

	if (!template)
		template = CLANG_BPF_CMD_DEFAULT_TEMPLATE;

	err = search_program(llvm_param.clang_path,
			     "clang", clang_path);
	if (err) {
		pr_err(
"ERROR:\tunable to find clang.\n"
"Hint:\tTry to install latest clang/llvm to support BPF. Check your $PATH\n"
"     \tand 'clang-path' option in [llvm] section of ~/.perfconfig.\n");
		version_notice();
		return -ENOENT;
	}

	/*
	 * This is an optional work. Even it fail we can continue our
	 * work. Needn't to check error return.
	 */
	get_kbuild_opts(&kbuild_dir, &kbuild_include_opts);

	nr_cpus_avail = sysconf(_SC_NPROCESSORS_CONF);
	if (nr_cpus_avail <= 0) {
		pr_err(
"WARNING:\tunable to get available CPUs in this system: %s\n"
"        \tUse 128 instead.\n", strerror(errno));
		nr_cpus_avail = 128;
	}
	snprintf(nr_cpus_avail_str, sizeof(nr_cpus_avail_str), "%d",
		 nr_cpus_avail);

	if (fetch_kernel_version(&kernel_version, NULL, 0))
		kernel_version = 0;

	snprintf(linux_version_code_str, sizeof(linux_version_code_str),
		 "0x%x", kernel_version);

	force_set_env("NR_CPUS", nr_cpus_avail_str);
	force_set_env("LINUX_VERSION_CODE", linux_version_code_str);
	force_set_env("CLANG_EXEC", clang_path);
	force_set_env("CLANG_OPTIONS", clang_opt);
	force_set_env("KERNEL_INC_OPTIONS", kbuild_include_opts);
	force_set_env("WORKING_DIR", kbuild_dir ? : ".");

	/*
	 * Since we may reset clang's working dir, path of source file
	 * should be transferred into absolute path, except we want
	 * stdin to be source file (testing).
	 */
	force_set_env("CLANG_SOURCE",
		      (path[0] == '-') ? path :
		      make_nonrelative_path(path));

	pr_debug("llvm compiling command template: %s\n", template);
	err = read_from_pipe(template, &obj_buf, &obj_buf_sz);
	if (err) {
		pr_err("ERROR:\tunable to compile %s\n", path);
		pr_err("Hint:\tCheck error message shown above.\n");
		pr_err("Hint:\tYou can also pre-compile it into .o using:\n");
		pr_err("     \t\tclang -target bpf -O2 -c %s\n", path);
		pr_err("     \twith proper -I and -D options.\n");
		goto errout;
	}

	free(kbuild_dir);
	free(kbuild_include_opts);
	if (!p_obj_buf)
		free(obj_buf);
	else
		*p_obj_buf = obj_buf;

	if (p_obj_buf_sz)
		*p_obj_buf_sz = obj_buf_sz;
	return 0;
errout:
	free(kbuild_dir);
	free(kbuild_include_opts);
	free(obj_buf);
	if (p_obj_buf)
		*p_obj_buf = NULL;
	if (p_obj_buf_sz)
		*p_obj_buf_sz = 0;
	return err;
}

int llvm__search_clang(void)
{
	char clang_path[PATH_MAX];

	return search_program(llvm_param.clang_path, "clang", clang_path);
}