Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 589 insertions, 0 deletions

diff --git a/tools/perf/util/llvm-utils.c b/tools/perf/util/llvm-utils.c
new file mode 100644
index 000000000..650ffe336
--- /dev/null
+++ b/tools/perf/util/llvm-utils.c
@@ -0,0 +1,589 @@
+// 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);
+
+	err = -ENOMEM;
+	if (asprintf(&command_echo, "echo -n \"%s\"", template) < 0)
+		goto errout;
+
+	err = read_from_pipe(command_echo, (void **) &command_out, NULL);
+	if (err)
+		goto errout;
+
+	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);
+}