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().
  ...

6 files changed, 931 insertions, 0 deletions

diff --git a/tools/lib/api/fs/Build b/tools/lib/api/fs/Build
new file mode 100644
index 000000000..0f75b2865
--- /dev/null
+++ b/tools/lib/api/fs/Build
@@ -0,0 +1,3 @@
+libapi-y += fs.o
+libapi-y += tracing_path.o
+libapi-y += cgroup.o
diff --git a/tools/lib/api/fs/cgroup.c b/tools/lib/api/fs/cgroup.c
new file mode 100644
index 000000000..1573dae42
--- /dev/null
+++ b/tools/lib/api/fs/cgroup.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/stringify.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "fs.h"
+
+struct cgroupfs_cache_entry {
+	char	subsys[32];
+	char	mountpoint[PATH_MAX];
+};
+
+/* just cache last used one */
+static struct cgroupfs_cache_entry cached;
+
+int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys)
+{
+	FILE *fp;
+	char *line = NULL;
+	size_t len = 0;
+	char *p, *path;
+	char mountpoint[PATH_MAX];
+
+	if (!strcmp(cached.subsys, subsys)) {
+		if (strlen(cached.mountpoint) < maxlen) {
+			strcpy(buf, cached.mountpoint);
+			return 0;
+		}
+		return -1;
+	}
+
+	fp = fopen("/proc/mounts", "r");
+	if (!fp)
+		return -1;
+
+	/*
+	 * in order to handle split hierarchy, we need to scan /proc/mounts
+	 * and inspect every cgroupfs mount point to find one that has
+	 * the given subsystem.  If we found v1, just use it.  If not we can
+	 * use v2 path as a fallback.
+	 */
+	mountpoint[0] = '\0';
+
+	/*
+	 * The /proc/mounts has the follow format:
+	 *
+	 *   <devname> <mount point> <fs type> <options> ...
+	 *
+	 */
+	while (getline(&line, &len, fp) != -1) {
+		/* skip devname */
+		p = strchr(line, ' ');
+		if (p == NULL)
+			continue;
+
+		/* save the mount point */
+		path = ++p;
+		p = strchr(p, ' ');
+		if (p == NULL)
+			continue;
+
+		*p++ = '\0';
+
+		/* check filesystem type */
+		if (strncmp(p, "cgroup", 6))
+			continue;
+
+		if (p[6] == '2') {
+			/* save cgroup v2 path */
+			strcpy(mountpoint, path);
+			continue;
+		}
+
+		/* now we have cgroup v1, check the options for subsystem */
+		p += 7;
+
+		p = strstr(p, subsys);
+		if (p == NULL)
+			continue;
+
+		/* sanity check: it should be separated by a space or a comma */
+		if (!strchr(" ,", p[-1]) || !strchr(" ,", p[strlen(subsys)]))
+			continue;
+
+		strcpy(mountpoint, path);
+		break;
+	}
+	free(line);
+	fclose(fp);
+
+	strncpy(cached.subsys, subsys, sizeof(cached.subsys) - 1);
+	strcpy(cached.mountpoint, mountpoint);
+
+	if (mountpoint[0] && strlen(mountpoint) < maxlen) {
+		strcpy(buf, mountpoint);
+		return 0;
+	}
+	return -1;
+}
diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
new file mode 100644
index 000000000..82f53d81a
--- /dev/null
+++ b/tools/lib/api/fs/fs.c
@@ -0,0 +1,558 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/vfs.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/mount.h>
+
+#include "fs.h"
+#include "debug-internal.h"
+
+#define _STR(x) #x
+#define STR(x) _STR(x)
+
+#ifndef SYSFS_MAGIC
+#define SYSFS_MAGIC            0x62656572
+#endif
+
+#ifndef PROC_SUPER_MAGIC
+#define PROC_SUPER_MAGIC       0x9fa0
+#endif
+
+#ifndef DEBUGFS_MAGIC
+#define DEBUGFS_MAGIC          0x64626720
+#endif
+
+#ifndef TRACEFS_MAGIC
+#define TRACEFS_MAGIC          0x74726163
+#endif
+
+#ifndef HUGETLBFS_MAGIC
+#define HUGETLBFS_MAGIC        0x958458f6
+#endif
+
+#ifndef BPF_FS_MAGIC
+#define BPF_FS_MAGIC           0xcafe4a11
+#endif
+
+static const char * const sysfs__fs_known_mountpoints[] = {
+	"/sys",
+	0,
+};
+
+static const char * const procfs__known_mountpoints[] = {
+	"/proc",
+	0,
+};
+
+#ifndef DEBUGFS_DEFAULT_PATH
+#define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
+#endif
+
+static const char * const debugfs__known_mountpoints[] = {
+	DEBUGFS_DEFAULT_PATH,
+	"/debug",
+	0,
+};
+
+
+#ifndef TRACEFS_DEFAULT_PATH
+#define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
+#endif
+
+static const char * const tracefs__known_mountpoints[] = {
+	TRACEFS_DEFAULT_PATH,
+	"/sys/kernel/debug/tracing",
+	"/tracing",
+	"/trace",
+	0,
+};
+
+static const char * const hugetlbfs__known_mountpoints[] = {
+	0,
+};
+
+static const char * const bpf_fs__known_mountpoints[] = {
+	"/sys/fs/bpf",
+	0,
+};
+
+struct fs {
+	const char		*name;
+	const char * const	*mounts;
+	char			 path[PATH_MAX];
+	bool			 found;
+	bool			 checked;
+	long			 magic;
+};
+
+enum {
+	FS__SYSFS   = 0,
+	FS__PROCFS  = 1,
+	FS__DEBUGFS = 2,
+	FS__TRACEFS = 3,
+	FS__HUGETLBFS = 4,
+	FS__BPF_FS = 5,
+};
+
+#ifndef TRACEFS_MAGIC
+#define TRACEFS_MAGIC 0x74726163
+#endif
+
+static struct fs fs__entries[] = {
+	[FS__SYSFS] = {
+		.name	= "sysfs",
+		.mounts	= sysfs__fs_known_mountpoints,
+		.magic	= SYSFS_MAGIC,
+		.checked = false,
+	},
+	[FS__PROCFS] = {
+		.name	= "proc",
+		.mounts	= procfs__known_mountpoints,
+		.magic	= PROC_SUPER_MAGIC,
+		.checked = false,
+	},
+	[FS__DEBUGFS] = {
+		.name	= "debugfs",
+		.mounts	= debugfs__known_mountpoints,
+		.magic	= DEBUGFS_MAGIC,
+		.checked = false,
+	},
+	[FS__TRACEFS] = {
+		.name	= "tracefs",
+		.mounts	= tracefs__known_mountpoints,
+		.magic	= TRACEFS_MAGIC,
+		.checked = false,
+	},
+	[FS__HUGETLBFS] = {
+		.name	= "hugetlbfs",
+		.mounts = hugetlbfs__known_mountpoints,
+		.magic	= HUGETLBFS_MAGIC,
+		.checked = false,
+	},
+	[FS__BPF_FS] = {
+		.name	= "bpf",
+		.mounts = bpf_fs__known_mountpoints,
+		.magic	= BPF_FS_MAGIC,
+		.checked = false,
+	},
+};
+
+static bool fs__read_mounts(struct fs *fs)
+{
+	bool found = false;
+	char type[100];
+	FILE *fp;
+
+	fp = fopen("/proc/mounts", "r");
+	if (fp == NULL)
+		return NULL;
+
+	while (!found &&
+	       fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
+		      fs->path, type) == 2) {
+
+		if (strcmp(type, fs->name) == 0)
+			found = true;
+	}
+
+	fclose(fp);
+	fs->checked = true;
+	return fs->found = found;
+}
+
+static int fs__valid_mount(const char *fs, long magic)
+{
+	struct statfs st_fs;
+
+	if (statfs(fs, &st_fs) < 0)
+		return -ENOENT;
+	else if ((long)st_fs.f_type != magic)
+		return -ENOENT;
+
+	return 0;
+}
+
+static bool fs__check_mounts(struct fs *fs)
+{
+	const char * const *ptr;
+
+	ptr = fs->mounts;
+	while (*ptr) {
+		if (fs__valid_mount(*ptr, fs->magic) == 0) {
+			fs->found = true;
+			strcpy(fs->path, *ptr);
+			return true;
+		}
+		ptr++;
+	}
+
+	return false;
+}
+
+static void mem_toupper(char *f, size_t len)
+{
+	while (len) {
+		*f = toupper(*f);
+		f++;
+		len--;
+	}
+}
+
+/*
+ * Check for "NAME_PATH" environment variable to override fs location (for
+ * testing). This matches the recommendation in Documentation/admin-guide/sysfs-rules.rst
+ * for SYSFS_PATH.
+ */
+static bool fs__env_override(struct fs *fs)
+{
+	char *override_path;
+	size_t name_len = strlen(fs->name);
+	/* name + "_PATH" + '\0' */
+	char upper_name[name_len + 5 + 1];
+
+	memcpy(upper_name, fs->name, name_len);
+	mem_toupper(upper_name, name_len);
+	strcpy(&upper_name[name_len], "_PATH");
+
+	override_path = getenv(upper_name);
+	if (!override_path)
+		return false;
+
+	fs->found = true;
+	fs->checked = true;
+	strncpy(fs->path, override_path, sizeof(fs->path) - 1);
+	fs->path[sizeof(fs->path) - 1] = '\0';
+	return true;
+}
+
+static const char *fs__get_mountpoint(struct fs *fs)
+{
+	if (fs__env_override(fs))
+		return fs->path;
+
+	if (fs__check_mounts(fs))
+		return fs->path;
+
+	if (fs__read_mounts(fs))
+		return fs->path;
+
+	return NULL;
+}
+
+static const char *fs__mountpoint(int idx)
+{
+	struct fs *fs = &fs__entries[idx];
+
+	if (fs->found)
+		return (const char *)fs->path;
+
+	/* the mount point was already checked for the mount point
+	 * but and did not exist, so return NULL to avoid scanning again.
+	 * This makes the found and not found paths cost equivalent
+	 * in case of multiple calls.
+	 */
+	if (fs->checked)
+		return NULL;
+
+	return fs__get_mountpoint(fs);
+}
+
+static const char *mount_overload(struct fs *fs)
+{
+	size_t name_len = strlen(fs->name);
+	/* "PERF_" + name + "_ENVIRONMENT" + '\0' */
+	char upper_name[5 + name_len + 12 + 1];
+
+	snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);
+	mem_toupper(upper_name, name_len);
+
+	return getenv(upper_name) ?: *fs->mounts;
+}
+
+static const char *fs__mount(int idx)
+{
+	struct fs *fs = &fs__entries[idx];
+	const char *mountpoint;
+
+	if (fs__mountpoint(idx))
+		return (const char *)fs->path;
+
+	mountpoint = mount_overload(fs);
+
+	if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)
+		return NULL;
+
+	return fs__check_mounts(fs) ? fs->path : NULL;
+}
+
+#define FS(name, idx)				\
+const char *name##__mountpoint(void)		\
+{						\
+	return fs__mountpoint(idx);		\
+}						\
+						\
+const char *name##__mount(void)			\
+{						\
+	return fs__mount(idx);			\
+}						\
+						\
+bool name##__configured(void)			\
+{						\
+	return name##__mountpoint() != NULL;	\
+}
+
+FS(sysfs,   FS__SYSFS);
+FS(procfs,  FS__PROCFS);
+FS(debugfs, FS__DEBUGFS);
+FS(tracefs, FS__TRACEFS);
+FS(hugetlbfs, FS__HUGETLBFS);
+FS(bpf_fs, FS__BPF_FS);
+
+int filename__read_int(const char *filename, int *value)
+{
+	char line[64];
+	int fd = open(filename, O_RDONLY), err = -1;
+
+	if (fd < 0)
+		return -1;
+
+	if (read(fd, line, sizeof(line)) > 0) {
+		*value = atoi(line);
+		err = 0;
+	}
+
+	close(fd);
+	return err;
+}
+
+static int filename__read_ull_base(const char *filename,
+				   unsigned long long *value, int base)
+{
+	char line[64];
+	int fd = open(filename, O_RDONLY), err = -1;
+
+	if (fd < 0)
+		return -1;
+
+	if (read(fd, line, sizeof(line)) > 0) {
+		*value = strtoull(line, NULL, base);
+		if (*value != ULLONG_MAX)
+			err = 0;
+	}
+
+	close(fd);
+	return err;
+}
+
+/*
+ * Parses @value out of @filename with strtoull.
+ * By using 16 for base to treat the number as hex.
+ */
+int filename__read_xll(const char *filename, unsigned long long *value)
+{
+	return filename__read_ull_base(filename, value, 16);
+}
+
+/*
+ * Parses @value out of @filename with strtoull.
+ * By using 0 for base, the strtoull detects the
+ * base automatically (see man strtoull).
+ */
+int filename__read_ull(const char *filename, unsigned long long *value)
+{
+	return filename__read_ull_base(filename, value, 0);
+}
+
+#define STRERR_BUFSIZE  128     /* For the buffer size of strerror_r */
+
+int filename__read_str(const char *filename, char **buf, size_t *sizep)
+{
+	size_t size = 0, alloc_size = 0;
+	void *bf = NULL, *nbf;
+	int fd, n, err = 0;
+	char sbuf[STRERR_BUFSIZE];
+
+	fd = open(filename, O_RDONLY);
+	if (fd < 0)
+		return -errno;
+
+	do {
+		if (size == alloc_size) {
+			alloc_size += BUFSIZ;
+			nbf = realloc(bf, alloc_size);
+			if (!nbf) {
+				err = -ENOMEM;
+				break;
+			}
+
+			bf = nbf;
+		}
+
+		n = read(fd, bf + size, alloc_size - size);
+		if (n < 0) {
+			if (size) {
+				pr_warn("read failed %d: %s\n", errno,
+					strerror_r(errno, sbuf, sizeof(sbuf)));
+				err = 0;
+			} else
+				err = -errno;
+
+			break;
+		}
+
+		size += n;
+	} while (n > 0);
+
+	if (!err) {
+		*sizep = size;
+		*buf   = bf;
+	} else
+		free(bf);
+
+	close(fd);
+	return err;
+}
+
+int filename__write_int(const char *filename, int value)
+{
+	int fd = open(filename, O_WRONLY), err = -1;
+	char buf[64];
+
+	if (fd < 0)
+		return err;
+
+	sprintf(buf, "%d", value);
+	if (write(fd, buf, sizeof(buf)) == sizeof(buf))
+		err = 0;
+
+	close(fd);
+	return err;
+}
+
+int procfs__read_str(const char *entry, char **buf, size_t *sizep)
+{
+	char path[PATH_MAX];
+	const char *procfs = procfs__mountpoint();
+
+	if (!procfs)
+		return -1;
+
+	snprintf(path, sizeof(path), "%s/%s", procfs, entry);
+
+	return filename__read_str(path, buf, sizep);
+}
+
+static int sysfs__read_ull_base(const char *entry,
+				unsigned long long *value, int base)
+{
+	char path[PATH_MAX];
+	const char *sysfs = sysfs__mountpoint();
+
+	if (!sysfs)
+		return -1;
+
+	snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+	return filename__read_ull_base(path, value, base);
+}
+
+int sysfs__read_xll(const char *entry, unsigned long long *value)
+{
+	return sysfs__read_ull_base(entry, value, 16);
+}
+
+int sysfs__read_ull(const char *entry, unsigned long long *value)
+{
+	return sysfs__read_ull_base(entry, value, 0);
+}
+
+int sysfs__read_int(const char *entry, int *value)
+{
+	char path[PATH_MAX];
+	const char *sysfs = sysfs__mountpoint();
+
+	if (!sysfs)
+		return -1;
+
+	snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+	return filename__read_int(path, value);
+}
+
+int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
+{
+	char path[PATH_MAX];
+	const char *sysfs = sysfs__mountpoint();
+
+	if (!sysfs)
+		return -1;
+
+	snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+	return filename__read_str(path, buf, sizep);
+}
+
+int sysfs__read_bool(const char *entry, bool *value)
+{
+	char *buf;
+	size_t size;
+	int ret;
+
+	ret = sysfs__read_str(entry, &buf, &size);
+	if (ret < 0)
+		return ret;
+
+	switch (buf[0]) {
+	case '1':
+	case 'y':
+	case 'Y':
+		*value = true;
+		break;
+	case '0':
+	case 'n':
+	case 'N':
+		*value = false;
+		break;
+	default:
+		ret = -1;
+	}
+
+	free(buf);
+
+	return ret;
+}
+int sysctl__read_int(const char *sysctl, int *value)
+{
+	char path[PATH_MAX];
+	const char *procfs = procfs__mountpoint();
+
+	if (!procfs)
+		return -1;
+
+	snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
+
+	return filename__read_int(path, value);
+}
+
+int sysfs__write_int(const char *entry, int value)
+{
+	char path[PATH_MAX];
+	const char *sysfs = sysfs__mountpoint();
+
+	if (!sysfs)
+		return -1;
+
+	if (snprintf(path, sizeof(path), "%s/%s", sysfs, entry) >= PATH_MAX)
+		return -1;
+
+	return filename__write_int(path, value);
+}
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
new file mode 100644
index 000000000..aa222ca30
--- /dev/null
+++ b/tools/lib/api/fs/fs.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __API_FS__
+#define __API_FS__
+
+#include <stdbool.h>
+#include <unistd.h>
+
+/*
+ * On most systems <limits.h> would have given us this, but  not on some systems
+ * (e.g. GNU/Hurd).
+ */
+#ifndef PATH_MAX
+#define PATH_MAX 4096
+#endif
+
+#define FS(name)				\
+	const char *name##__mountpoint(void);	\
+	const char *name##__mount(void);	\
+	bool name##__configured(void);		\
+
+/*
+ * The xxxx__mountpoint() entry points find the first match mount point for each
+ * filesystems listed below, where xxxx is the filesystem type.
+ *
+ * The interface is as follows:
+ *
+ * - If a mount point is found on first call, it is cached and used for all
+ *   subsequent calls.
+ *
+ * - If a mount point is not found, NULL is returned on first call and all
+ *   subsequent calls.
+ */
+FS(sysfs)
+FS(procfs)
+FS(debugfs)
+FS(tracefs)
+FS(hugetlbfs)
+FS(bpf_fs)
+
+#undef FS
+
+
+int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys);
+
+int filename__read_int(const char *filename, int *value);
+int filename__read_ull(const char *filename, unsigned long long *value);
+int filename__read_xll(const char *filename, unsigned long long *value);
+int filename__read_str(const char *filename, char **buf, size_t *sizep);
+
+int filename__write_int(const char *filename, int value);
+
+int procfs__read_str(const char *entry, char **buf, size_t *sizep);
+
+int sysctl__read_int(const char *sysctl, int *value);
+int sysfs__read_int(const char *entry, int *value);
+int sysfs__read_ull(const char *entry, unsigned long long *value);
+int sysfs__read_xll(const char *entry, unsigned long long *value);
+int sysfs__read_str(const char *entry, char **buf, size_t *sizep);
+int sysfs__read_bool(const char *entry, bool *value);
+
+int sysfs__write_int(const char *entry, int value);
+#endif /* __API_FS__ */
diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c
new file mode 100644
index 000000000..b8e457c84
--- /dev/null
+++ b/tools/lib/api/fs/tracing_path.c
@@ -0,0 +1,183 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <linux/string.h>
+#include <errno.h>
+#include <unistd.h>
+#include "fs.h"
+
+#include "tracing_path.h"
+
+static char tracing_mnt[PATH_MAX]  = "/sys/kernel/debug";
+static char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
+static char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
+
+static void __tracing_path_set(const char *tracing, const char *mountpoint)
+{
+	snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
+	snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
+		 mountpoint, tracing);
+	snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
+		 mountpoint, tracing, "events");
+}
+
+static const char *tracing_path_tracefs_mount(void)
+{
+	const char *mnt;
+
+	mnt = tracefs__mount();
+	if (!mnt)
+		return NULL;
+
+	__tracing_path_set("", mnt);
+
+	return tracing_path;
+}
+
+static const char *tracing_path_debugfs_mount(void)
+{
+	const char *mnt;
+
+	mnt = debugfs__mount();
+	if (!mnt)
+		return NULL;
+
+	__tracing_path_set("tracing/", mnt);
+
+	return tracing_path;
+}
+
+const char *tracing_path_mount(void)
+{
+	const char *mnt;
+
+	mnt = tracing_path_tracefs_mount();
+	if (mnt)
+		return mnt;
+
+	mnt = tracing_path_debugfs_mount();
+
+	return mnt;
+}
+
+void tracing_path_set(const char *mntpt)
+{
+	__tracing_path_set("tracing/", mntpt);
+}
+
+char *get_tracing_file(const char *name)
+{
+	char *file;
+
+	if (asprintf(&file, "%s/%s", tracing_path_mount(), name) < 0)
+		return NULL;
+
+	return file;
+}
+
+void put_tracing_file(char *file)
+{
+	free(file);
+}
+
+char *get_events_file(const char *name)
+{
+	char *file;
+
+	if (asprintf(&file, "%s/events/%s", tracing_path_mount(), name) < 0)
+		return NULL;
+
+	return file;
+}
+
+void put_events_file(char *file)
+{
+	free(file);
+}
+
+DIR *tracing_events__opendir(void)
+{
+	DIR *dir = NULL;
+	char *path = get_tracing_file("events");
+
+	if (path) {
+		dir = opendir(path);
+		put_events_file(path);
+	}
+
+	return dir;
+}
+
+int tracing_events__scandir_alphasort(struct dirent ***namelist)
+{
+	char *path = get_tracing_file("events");
+	int ret;
+
+	if (!path) {
+		*namelist = NULL;
+		return 0;
+	}
+
+	ret = scandir(path, namelist, NULL, alphasort);
+	put_events_file(path);
+
+	return ret;
+}
+
+int tracing_path__strerror_open_tp(int err, char *buf, size_t size,
+				   const char *sys, const char *name)
+{
+	char sbuf[128];
+	char filename[PATH_MAX];
+
+	snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*");
+
+	switch (err) {
+	case ENOENT:
+		/*
+		 * We will get here if we can't find the tracepoint, but one of
+		 * debugfs or tracefs is configured, which means you probably
+		 * want some tracepoint which wasn't compiled in your kernel.
+		 * - jirka
+		 */
+		if (debugfs__configured() || tracefs__configured()) {
+			/* sdt markers */
+			if (!strncmp(filename, "sdt_", 4)) {
+				snprintf(buf, size,
+					"Error:\tFile %s/%s not found.\n"
+					"Hint:\tSDT event cannot be directly recorded on.\n"
+					"\tPlease first use 'perf probe %s:%s' before recording it.\n",
+					tracing_events_path, filename, sys, name);
+			} else {
+				snprintf(buf, size,
+					 "Error:\tFile %s/%s not found.\n"
+					 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
+					 tracing_events_path, filename);
+			}
+			break;
+		}
+		snprintf(buf, size, "%s",
+			 "Error:\tUnable to find debugfs/tracefs\n"
+			 "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n"
+			 "Hint:\tIs the debugfs/tracefs filesystem mounted?\n"
+			 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
+		break;
+	case EACCES: {
+		snprintf(buf, size,
+			 "Error:\tNo permissions to read %s/%s\n"
+			 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
+			 tracing_events_path, filename, tracing_path_mount());
+	}
+		break;
+	default:
+		snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf)));
+		break;
+	}
+
+	return 0;
+}
diff --git a/tools/lib/api/fs/tracing_path.h b/tools/lib/api/fs/tracing_path.h
new file mode 100644
index 000000000..fc6347c11
--- /dev/null
+++ b/tools/lib/api/fs/tracing_path.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __API_FS_TRACING_PATH_H
+#define __API_FS_TRACING_PATH_H
+
+#include <linux/types.h>
+#include <dirent.h>
+
+DIR *tracing_events__opendir(void);
+int tracing_events__scandir_alphasort(struct dirent ***namelist);
+
+void tracing_path_set(const char *mountpoint);
+const char *tracing_path_mount(void);
+
+char *get_tracing_file(const char *name);
+void put_tracing_file(char *file);
+
+char *get_events_file(const char *name);
+void put_events_file(char *file);
+
+#define zput_events_file(ptr) ({ free(*ptr); *ptr = NULL; })
+
+int tracing_path__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name);
+#endif /* __API_FS_TRACING_PATH_H */