perf parse-events: Remove BPF event support

New features like the BPF --filter support in perf record have made the
BPF event functionality somewhat redundant. As shown by commit
fcb027c1a4f6 ("perf tools: Revert enable indices setting syntax for BPF
map") and commit 14e4b9f4289a ("perf trace: Raw augmented syscalls fix
libbpf 1.0+ compatibility") the BPF event support hasn't been well
maintained and it adds considerable complexity in areas like event
parsing, not least as '/' is a separator for event modifiers as well as
in paths.

This patch removes support in the event parser for BPF events and then
the associated functions are removed. This leads to the removal of whole
source files like bpf-loader.c.  Removing support means that augmented
syscalls in perf trace is broken, this will be fixed in a later commit
adding support using BPF skeletons.

The removal of BPF events causes an unused label warning from flex
generated code, so update build to ignore it:

  ```
  util/parse-events-flex.c:2704:1: error: label ‘find_rule’ defined but not used [-Werror=unused-label]
  2704 | find_rule: /* we branch to this label when backing up */
  ```

Committer notes:

Extracted from a larger patch that was also removing the support for
linking with libllvm and libclang, that were an alternative to using an
external clang execution to compile the .c event source code into BPF
bytecode.

Testing it:

  # perf trace -e /home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.c
  event syntax error: '/home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.c'
                        \___ Bad event or PMU

  Unabled to find PMU or event on a PMU of 'home'

  Initial error:
  event syntax error: '/home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.c'
                        \___ Cannot find PMU `home'. Missing kernel support?
  Run 'perf list' for a list of valid events

   Usage: perf trace [<options>] [<command>]
      or: perf trace [<options>] -- <command> [<options>]
      or: perf trace record [<options>] [<command>]
      or: perf trace record [<options>] -- <command> [<options>]

      -e, --event <event>   event/syscall selector. use 'perf list' to list available events
  #

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Carsten Haitzler <carsten.haitzler@arm.com>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Fangrui Song <maskray@google.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Tom Rix <trix@redhat.com>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Wang ShaoBo <bobo.shaobowang@huawei.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Cc: bpf@vger.kernel.org
Cc: llvm@lists.linux.dev
Link: https://lore.kernel.org/r/20230810184853.2860737-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 0 insertions, 612 deletions

diff --git a/tools/perf/util/llvm-utils.c b/tools/perf/util/llvm-utils.c
deleted file mode 100644
index c6c9c2228578..000000000000
--- a/tools/perf/util/llvm-utils.c
+++ /dev/null
@@ -1,612 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Copyright (C) 2015, Wang Nan <wangnan0@huawei.com>
- * Copyright (C) 2015, Huawei Inc.
- */
-
-#include <errno.h>
-#include <limits.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <linux/err.h>
-#include <linux/string.h>
-#include <linux/zalloc.h>
-#include "debug.h"
-#include "llvm-utils.h"
-#include "config.h"
-#include "util.h"
-#include <sys/wait.h>
-#include <subcmd/exec-cmd.h>
-
-#define CLANG_BPF_CMD_DEFAULT_TEMPLATE				\
-		"$CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS "\
-		"-DLINUX_VERSION_CODE=$LINUX_VERSION_CODE "	\
-		"$CLANG_OPTIONS $PERF_BPF_INC_OPTIONS $KERNEL_INC_OPTIONS " \
-		"-Wno-unused-value -Wno-pointer-sign "		\
-		"-working-directory $WORKING_DIR "		\
-		"-c \"$CLANG_SOURCE\" --target=bpf $CLANG_EMIT_LLVM -g -O2 -o - $LLVM_OPTIONS_PIPE"
-
-struct llvm_param llvm_param = {
-	.clang_path = "clang",
-	.llc_path = "llc",
-	.clang_bpf_cmd_template = CLANG_BPF_CMD_DEFAULT_TEMPLATE,
-	.clang_opt = NULL,
-	.opts = NULL,
-	.kbuild_dir = NULL,
-	.kbuild_opts = NULL,
-	.user_set_param = false,
-};
-
-static void version_notice(void);
-
-int perf_llvm_config(const char *var, const char *value)
-{
-	if (!strstarts(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 if (!strcmp(var, "dump-obj"))
-		llvm_param.dump_obj = !!perf_config_bool(var, value);
-	else if (!strcmp(var, "opts"))
-		llvm_param.opts = strdup(value);
-	else {
-		pr_debug("Invalid LLVM config option: %s\n", value);
-		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;
-}
-
-static int search_program_and_warn(const char *def, const char *name,
-				   char *output)
-{
-	int ret = search_program(def, name, output);
-
-	if (ret) {
-		pr_err("ERROR:\tunable to find %s.\n"
-		       "Hint:\tTry to install latest clang/llvm to support BPF. Check your $PATH\n"
-		       "     \tand '%s-path' option in [llvm] section of ~/.perfconfig.\n",
-		       name, name);
-		version_notice();
-	}
-	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;
-	char serr[STRERR_BUFSIZE];
-
-	file = popen(cmd, "r");
-	if (!file) {
-		pr_err("ERROR: unable to popen cmd: %s\n",
-		       str_error_r(errno, serr, sizeof(serr)));
-		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",
-		       str_error_r(errno, serr, sizeof(serr)));
-		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\thttps://apt.llvm.org/\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 $PERF_BPF_INC_OPTIONS \\\n"
-"     \t     -working-directory $WORKING_DIR -c $CLANG_SOURCE \\\n"
-"     \t     -emit-llvm -o - | /path/to/llc -march=bpf -filetype=obj -o -\"\n"
-"     \t(Replace /path/to/llc with path to your llc)\n\n"
-);
-}
-
-static int detect_kbuild_dir(char **kbuild_dir)
-{
-	const char *test_dir = llvm_param.kbuild_dir;
-	const char *prefix_dir = "";
-	const char *suffix_dir = "";
-
-	/* _UTSNAME_LENGTH is 65 */
-	char release[128];
-
-	char *autoconf_path;
-
-	int err;
-
-	if (!test_dir) {
-		err = fetch_kernel_version(NULL, release,
-					   sizeof(release));
-		if (err)
-			return -EINVAL;
-
-		test_dir = release;
-		prefix_dir = "/lib/modules/";
-		suffix_dir = "/build";
-	}
-
-	err = asprintf(&autoconf_path, "%s%s%s/include/generated/autoconf.h",
-		       prefix_dir, test_dir, suffix_dir);
-	if (err < 0)
-		return -ENOMEM;
-
-	if (access(autoconf_path, R_OK) == 0) {
-		free(autoconf_path);
-
-		err = asprintf(kbuild_dir, "%s%s%s", prefix_dir, test_dir,
-			       suffix_dir);
-		if (err < 0)
-			return -ENOMEM;
-		return 0;
-	}
-	pr_debug("%s: Couldn't find \"%s\", missing kernel-devel package?.\n",
-		 __func__, autoconf_path);
-	free(autoconf_path);
-	return -ENOENT;
-}
-
-static const char *kinc_fetch_script =
-"#!/usr/bin/env sh\n"
-"if ! test -d \"$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"
-"\t\\$(CC) -c -o \\$@ \\$<\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";
-
-void llvm__get_kbuild_opts(char **kbuild_dir, char **kbuild_include_opts)
-{
-	static char *saved_kbuild_dir;
-	static char *saved_kbuild_include_opts;
-	int err;
-
-	if (!kbuild_dir || !kbuild_include_opts)
-		return;
-
-	*kbuild_dir = NULL;
-	*kbuild_include_opts = NULL;
-
-	if (saved_kbuild_dir && saved_kbuild_include_opts &&
-	    !IS_ERR(saved_kbuild_dir) && !IS_ERR(saved_kbuild_include_opts)) {
-		*kbuild_dir = strdup(saved_kbuild_dir);
-		*kbuild_include_opts = strdup(saved_kbuild_include_opts);
-
-		if (*kbuild_dir && *kbuild_include_opts)
-			return;
-
-		zfree(kbuild_dir);
-		zfree(kbuild_include_opts);
-		/*
-		 * Don't fall through: it may breaks saved_kbuild_dir and
-		 * saved_kbuild_include_opts if detect them again when
-		 * memory is low.
-		 */
-		return;
-	}
-
-	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");
-		goto errout;
-	}
-
-	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");
-		goto errout;
-	}
-
-	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);
-
-		zfree(kbuild_dir);
-		goto errout;
-	}
-
-	pr_debug("include option is set to %s\n", *kbuild_include_opts);
-
-	saved_kbuild_dir = strdup(*kbuild_dir);
-	saved_kbuild_include_opts = strdup(*kbuild_include_opts);
-
-	if (!saved_kbuild_dir || !saved_kbuild_include_opts) {
-		zfree(&saved_kbuild_dir);
-		zfree(&saved_kbuild_include_opts);
-	}
-	return;
-errout:
-	saved_kbuild_dir = ERR_PTR(-EINVAL);
-	saved_kbuild_include_opts = ERR_PTR(-EINVAL);
-}
-
-int llvm__get_nr_cpus(void)
-{
-	static int nr_cpus_avail = 0;
-	char serr[STRERR_BUFSIZE];
-
-	if (nr_cpus_avail > 0)
-		return nr_cpus_avail;
-
-	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", str_error_r(errno, serr, sizeof(serr)));
-		nr_cpus_avail = 128;
-	}
-	return nr_cpus_avail;
-}
-
-void llvm__dump_obj(const char *path, void *obj_buf, size_t size)
-{
-	char *obj_path = strdup(path);
-	FILE *fp;
-	char *p;
-
-	if (!obj_path) {
-		pr_warning("WARNING: Not enough memory, skip object dumping\n");
-		return;
-	}
-
-	p = strrchr(obj_path, '.');
-	if (!p || (strcmp(p, ".c") != 0)) {
-		pr_warning("WARNING: invalid llvm source path: '%s', skip object dumping\n",
-			   obj_path);
-		goto out;
-	}
-
-	p[1] = 'o';
-	fp = fopen(obj_path, "wb");
-	if (!fp) {
-		pr_warning("WARNING: failed to open '%s': %s, skip object dumping\n",
-			   obj_path, strerror(errno));
-		goto out;
-	}
-
-	pr_debug("LLVM: dumping %s\n", obj_path);
-	if (fwrite(obj_buf, size, 1, fp) != 1)
-		pr_debug("WARNING: failed to write to file '%s': %s, skip object dumping\n", obj_path, strerror(errno));
-	fclose(fp);
-out:
-	free(obj_path);
-}
-
-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], llc_path[PATH_MAX], abspath[PATH_MAX], nr_cpus_avail_str[64];
-	char serr[STRERR_BUFSIZE];
-	char *kbuild_dir = NULL, *kbuild_include_opts = NULL,
-	     *perf_bpf_include_opts = NULL;
-	const char *template = llvm_param.clang_bpf_cmd_template;
-	char *pipe_template = NULL;
-	const char *opts = llvm_param.opts;
-	char *command_echo = NULL, *command_out;
-	char *libbpf_include_dir = system_path(LIBBPF_INCLUDE_DIR);
-
-	if (path[0] != '-' && realpath(path, abspath) == NULL) {
-		err = errno;
-		pr_err("ERROR: problems with path %s: %s\n",
-		       path, str_error_r(err, serr, sizeof(serr)));
-		return -err;
-	}
-
-	if (!template)
-		template = CLANG_BPF_CMD_DEFAULT_TEMPLATE;
-
-	err = search_program_and_warn(llvm_param.clang_path,
-			     "clang", clang_path);
-	if (err)
-		return -ENOENT;
-
-	/*
-	 * This is an optional work. Even it fail we can continue our
-	 * work. Needn't check error return.
-	 */
-	llvm__get_kbuild_opts(&kbuild_dir, &kbuild_include_opts);
-
-	nr_cpus_avail = llvm__get_nr_cpus();
-	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);
-	if (asprintf(&perf_bpf_include_opts, "-I%s/", libbpf_include_dir) < 0)
-		goto errout;
-	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("PERF_BPF_INC_OPTIONS", perf_bpf_include_opts);
-	force_set_env("WORKING_DIR", kbuild_dir ? : ".");
-
-	if (opts) {
-		err = search_program_and_warn(llvm_param.llc_path, "llc", llc_path);
-		if (err)
-			goto errout;
-
-		err = -ENOMEM;
-		if (asprintf(&pipe_template, "%s -emit-llvm | %s -march=bpf %s -filetype=obj -o -",
-			      template, llc_path, opts) < 0) {
-			pr_err("ERROR:\tnot enough memory to setup command line\n");
-			goto errout;
-		}
-
-		template = pipe_template;
-
-	}
-
-	/*
-	 * 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 : abspath);
-
-	pr_debug("llvm compiling command template: %s\n", template);
-
-	/*
-	 * Below, substitute control characters for values that can cause the
-	 * echo to misbehave, then substitute the values back.
-	 */
-	err = -ENOMEM;
-	if (asprintf(&command_echo, "echo -n \a%s\a", template) < 0)
-		goto errout;
-
-#define SWAP_CHAR(a, b) do { if (*p == a) *p = b; } while (0)
-	for (char *p = command_echo; *p; p++) {
-		SWAP_CHAR('<', '\001');
-		SWAP_CHAR('>', '\002');
-		SWAP_CHAR('"', '\003');
-		SWAP_CHAR('\'', '\004');
-		SWAP_CHAR('|', '\005');
-		SWAP_CHAR('&', '\006');
-		SWAP_CHAR('\a', '"');
-	}
-	err = read_from_pipe(command_echo, (void **) &command_out, NULL);
-	if (err)
-		goto errout;
-
-	for (char *p = command_out; *p; p++) {
-		SWAP_CHAR('\001', '<');
-		SWAP_CHAR('\002', '>');
-		SWAP_CHAR('\003', '"');
-		SWAP_CHAR('\004', '\'');
-		SWAP_CHAR('\005', '|');
-		SWAP_CHAR('\006', '&');
-	}
-#undef SWAP_CHAR
-	pr_debug("llvm compiling command : %s\n", command_out);
-
-	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(command_echo);
-	free(command_out);
-	free(kbuild_dir);
-	free(kbuild_include_opts);
-	free(perf_bpf_include_opts);
-	free(libbpf_include_dir);
-
-	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(command_echo);
-	free(kbuild_dir);
-	free(kbuild_include_opts);
-	free(obj_buf);
-	free(perf_bpf_include_opts);
-	free(libbpf_include_dir);
-	free(pipe_template);
-	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_and_warn(llvm_param.clang_path, "clang", clang_path);
-}