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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /kernel/trace/trace_functions.c
downloadlinux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz
linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip
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(). ...
Diffstat (limited to 'kernel/trace/trace_functions.c')
-rw-r--r--kernel/trace/trace_functions.c974
1 files changed, 974 insertions, 0 deletions
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
new file mode 100644
index 000000000..9f1bfbe10
--- /dev/null
+++ b/kernel/trace/trace_functions.c
@@ -0,0 +1,974 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ring buffer based function tracer
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
+ *
+ * Based on code from the latency_tracer, that is:
+ *
+ * Copyright (C) 2004-2006 Ingo Molnar
+ * Copyright (C) 2004 Nadia Yvette Chambers
+ */
+#include <linux/ring_buffer.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+
+#include "trace.h"
+
+static void tracing_start_function_trace(struct trace_array *tr);
+static void tracing_stop_function_trace(struct trace_array *tr);
+static void
+function_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct ftrace_regs *fregs);
+static void
+function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct ftrace_regs *fregs);
+static void
+function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct ftrace_regs *fregs);
+static void
+function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op,
+ struct ftrace_regs *fregs);
+static struct tracer_flags func_flags;
+
+/* Our option */
+enum {
+
+ TRACE_FUNC_NO_OPTS = 0x0, /* No flags set. */
+ TRACE_FUNC_OPT_STACK = 0x1,
+ TRACE_FUNC_OPT_NO_REPEATS = 0x2,
+
+ /* Update this to next highest bit. */
+ TRACE_FUNC_OPT_HIGHEST_BIT = 0x4
+};
+
+#define TRACE_FUNC_OPT_MASK (TRACE_FUNC_OPT_HIGHEST_BIT - 1)
+
+int ftrace_allocate_ftrace_ops(struct trace_array *tr)
+{
+ struct ftrace_ops *ops;
+
+ /* The top level array uses the "global_ops" */
+ if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
+ return 0;
+
+ ops = kzalloc(sizeof(*ops), GFP_KERNEL);
+ if (!ops)
+ return -ENOMEM;
+
+ /* Currently only the non stack version is supported */
+ ops->func = function_trace_call;
+ ops->flags = FTRACE_OPS_FL_PID;
+
+ tr->ops = ops;
+ ops->private = tr;
+
+ return 0;
+}
+
+void ftrace_free_ftrace_ops(struct trace_array *tr)
+{
+ kfree(tr->ops);
+ tr->ops = NULL;
+}
+
+int ftrace_create_function_files(struct trace_array *tr,
+ struct dentry *parent)
+{
+ /*
+ * The top level array uses the "global_ops", and the files are
+ * created on boot up.
+ */
+ if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
+ return 0;
+
+ if (!tr->ops)
+ return -EINVAL;
+
+ ftrace_create_filter_files(tr->ops, parent);
+
+ return 0;
+}
+
+void ftrace_destroy_function_files(struct trace_array *tr)
+{
+ ftrace_destroy_filter_files(tr->ops);
+ ftrace_free_ftrace_ops(tr);
+}
+
+static ftrace_func_t select_trace_function(u32 flags_val)
+{
+ switch (flags_val & TRACE_FUNC_OPT_MASK) {
+ case TRACE_FUNC_NO_OPTS:
+ return function_trace_call;
+ case TRACE_FUNC_OPT_STACK:
+ return function_stack_trace_call;
+ case TRACE_FUNC_OPT_NO_REPEATS:
+ return function_no_repeats_trace_call;
+ case TRACE_FUNC_OPT_STACK | TRACE_FUNC_OPT_NO_REPEATS:
+ return function_stack_no_repeats_trace_call;
+ default:
+ return NULL;
+ }
+}
+
+static bool handle_func_repeats(struct trace_array *tr, u32 flags_val)
+{
+ if (!tr->last_func_repeats &&
+ (flags_val & TRACE_FUNC_OPT_NO_REPEATS)) {
+ tr->last_func_repeats = alloc_percpu(struct trace_func_repeats);
+ if (!tr->last_func_repeats)
+ return false;
+ }
+
+ return true;
+}
+
+static int function_trace_init(struct trace_array *tr)
+{
+ ftrace_func_t func;
+ /*
+ * Instance trace_arrays get their ops allocated
+ * at instance creation. Unless it failed
+ * the allocation.
+ */
+ if (!tr->ops)
+ return -ENOMEM;
+
+ func = select_trace_function(func_flags.val);
+ if (!func)
+ return -EINVAL;
+
+ if (!handle_func_repeats(tr, func_flags.val))
+ return -ENOMEM;
+
+ ftrace_init_array_ops(tr, func);
+
+ tr->array_buffer.cpu = raw_smp_processor_id();
+
+ tracing_start_cmdline_record();
+ tracing_start_function_trace(tr);
+ return 0;
+}
+
+static void function_trace_reset(struct trace_array *tr)
+{
+ tracing_stop_function_trace(tr);
+ tracing_stop_cmdline_record();
+ ftrace_reset_array_ops(tr);
+}
+
+static void function_trace_start(struct trace_array *tr)
+{
+ tracing_reset_online_cpus(&tr->array_buffer);
+}
+
+static void
+function_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct ftrace_regs *fregs)
+{
+ struct trace_array *tr = op->private;
+ struct trace_array_cpu *data;
+ unsigned int trace_ctx;
+ int bit;
+ int cpu;
+
+ if (unlikely(!tr->function_enabled))
+ return;
+
+ bit = ftrace_test_recursion_trylock(ip, parent_ip);
+ if (bit < 0)
+ return;
+
+ trace_ctx = tracing_gen_ctx();
+
+ cpu = smp_processor_id();
+ data = per_cpu_ptr(tr->array_buffer.data, cpu);
+ if (!atomic_read(&data->disabled))
+ trace_function(tr, ip, parent_ip, trace_ctx);
+
+ ftrace_test_recursion_unlock(bit);
+}
+
+#ifdef CONFIG_UNWINDER_ORC
+/*
+ * Skip 2:
+ *
+ * function_stack_trace_call()
+ * ftrace_call()
+ */
+#define STACK_SKIP 2
+#else
+/*
+ * Skip 3:
+ * __trace_stack()
+ * function_stack_trace_call()
+ * ftrace_call()
+ */
+#define STACK_SKIP 3
+#endif
+
+static void
+function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct ftrace_regs *fregs)
+{
+ struct trace_array *tr = op->private;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+ long disabled;
+ int cpu;
+ unsigned int trace_ctx;
+
+ if (unlikely(!tr->function_enabled))
+ return;
+
+ /*
+ * Need to use raw, since this must be called before the
+ * recursive protection is performed.
+ */
+ local_irq_save(flags);
+ cpu = raw_smp_processor_id();
+ data = per_cpu_ptr(tr->array_buffer.data, cpu);
+ disabled = atomic_inc_return(&data->disabled);
+
+ if (likely(disabled == 1)) {
+ trace_ctx = tracing_gen_ctx_flags(flags);
+ trace_function(tr, ip, parent_ip, trace_ctx);
+ __trace_stack(tr, trace_ctx, STACK_SKIP);
+ }
+
+ atomic_dec(&data->disabled);
+ local_irq_restore(flags);
+}
+
+static inline bool is_repeat_check(struct trace_array *tr,
+ struct trace_func_repeats *last_info,
+ unsigned long ip, unsigned long parent_ip)
+{
+ if (last_info->ip == ip &&
+ last_info->parent_ip == parent_ip &&
+ last_info->count < U16_MAX) {
+ last_info->ts_last_call =
+ ring_buffer_time_stamp(tr->array_buffer.buffer);
+ last_info->count++;
+ return true;
+ }
+
+ return false;
+}
+
+static inline void process_repeats(struct trace_array *tr,
+ unsigned long ip, unsigned long parent_ip,
+ struct trace_func_repeats *last_info,
+ unsigned int trace_ctx)
+{
+ if (last_info->count) {
+ trace_last_func_repeats(tr, last_info, trace_ctx);
+ last_info->count = 0;
+ }
+
+ last_info->ip = ip;
+ last_info->parent_ip = parent_ip;
+}
+
+static void
+function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op,
+ struct ftrace_regs *fregs)
+{
+ struct trace_func_repeats *last_info;
+ struct trace_array *tr = op->private;
+ struct trace_array_cpu *data;
+ unsigned int trace_ctx;
+ unsigned long flags;
+ int bit;
+ int cpu;
+
+ if (unlikely(!tr->function_enabled))
+ return;
+
+ bit = ftrace_test_recursion_trylock(ip, parent_ip);
+ if (bit < 0)
+ return;
+
+ cpu = smp_processor_id();
+ data = per_cpu_ptr(tr->array_buffer.data, cpu);
+ if (atomic_read(&data->disabled))
+ goto out;
+
+ /*
+ * An interrupt may happen at any place here. But as far as I can see,
+ * the only damage that this can cause is to mess up the repetition
+ * counter without valuable data being lost.
+ * TODO: think about a solution that is better than just hoping to be
+ * lucky.
+ */
+ last_info = per_cpu_ptr(tr->last_func_repeats, cpu);
+ if (is_repeat_check(tr, last_info, ip, parent_ip))
+ goto out;
+
+ local_save_flags(flags);
+ trace_ctx = tracing_gen_ctx_flags(flags);
+ process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
+
+ trace_function(tr, ip, parent_ip, trace_ctx);
+
+out:
+ ftrace_test_recursion_unlock(bit);
+}
+
+static void
+function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op,
+ struct ftrace_regs *fregs)
+{
+ struct trace_func_repeats *last_info;
+ struct trace_array *tr = op->private;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+ long disabled;
+ int cpu;
+ unsigned int trace_ctx;
+
+ if (unlikely(!tr->function_enabled))
+ return;
+
+ /*
+ * Need to use raw, since this must be called before the
+ * recursive protection is performed.
+ */
+ local_irq_save(flags);
+ cpu = raw_smp_processor_id();
+ data = per_cpu_ptr(tr->array_buffer.data, cpu);
+ disabled = atomic_inc_return(&data->disabled);
+
+ if (likely(disabled == 1)) {
+ last_info = per_cpu_ptr(tr->last_func_repeats, cpu);
+ if (is_repeat_check(tr, last_info, ip, parent_ip))
+ goto out;
+
+ trace_ctx = tracing_gen_ctx_flags(flags);
+ process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
+
+ trace_function(tr, ip, parent_ip, trace_ctx);
+ __trace_stack(tr, trace_ctx, STACK_SKIP);
+ }
+
+ out:
+ atomic_dec(&data->disabled);
+ local_irq_restore(flags);
+}
+
+static struct tracer_opt func_opts[] = {
+#ifdef CONFIG_STACKTRACE
+ { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
+#endif
+ { TRACER_OPT(func-no-repeats, TRACE_FUNC_OPT_NO_REPEATS) },
+ { } /* Always set a last empty entry */
+};
+
+static struct tracer_flags func_flags = {
+ .val = TRACE_FUNC_NO_OPTS, /* By default: all flags disabled */
+ .opts = func_opts
+};
+
+static void tracing_start_function_trace(struct trace_array *tr)
+{
+ tr->function_enabled = 0;
+ register_ftrace_function(tr->ops);
+ tr->function_enabled = 1;
+}
+
+static void tracing_stop_function_trace(struct trace_array *tr)
+{
+ tr->function_enabled = 0;
+ unregister_ftrace_function(tr->ops);
+}
+
+static struct tracer function_trace;
+
+static int
+func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
+{
+ ftrace_func_t func;
+ u32 new_flags;
+
+ /* Do nothing if already set. */
+ if (!!set == !!(func_flags.val & bit))
+ return 0;
+
+ /* We can change this flag only when not running. */
+ if (tr->current_trace != &function_trace)
+ return 0;
+
+ new_flags = (func_flags.val & ~bit) | (set ? bit : 0);
+ func = select_trace_function(new_flags);
+ if (!func)
+ return -EINVAL;
+
+ /* Check if there's anything to change. */
+ if (tr->ops->func == func)
+ return 0;
+
+ if (!handle_func_repeats(tr, new_flags))
+ return -ENOMEM;
+
+ unregister_ftrace_function(tr->ops);
+ tr->ops->func = func;
+ register_ftrace_function(tr->ops);
+
+ return 0;
+}
+
+static struct tracer function_trace __tracer_data =
+{
+ .name = "function",
+ .init = function_trace_init,
+ .reset = function_trace_reset,
+ .start = function_trace_start,
+ .flags = &func_flags,
+ .set_flag = func_set_flag,
+ .allow_instances = true,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_function,
+#endif
+};
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+static void update_traceon_count(struct ftrace_probe_ops *ops,
+ unsigned long ip,
+ struct trace_array *tr, bool on,
+ void *data)
+{
+ struct ftrace_func_mapper *mapper = data;
+ long *count;
+ long old_count;
+
+ /*
+ * Tracing gets disabled (or enabled) once per count.
+ * This function can be called at the same time on multiple CPUs.
+ * It is fine if both disable (or enable) tracing, as disabling
+ * (or enabling) the second time doesn't do anything as the
+ * state of the tracer is already disabled (or enabled).
+ * What needs to be synchronized in this case is that the count
+ * only gets decremented once, even if the tracer is disabled
+ * (or enabled) twice, as the second one is really a nop.
+ *
+ * The memory barriers guarantee that we only decrement the
+ * counter once. First the count is read to a local variable
+ * and a read barrier is used to make sure that it is loaded
+ * before checking if the tracer is in the state we want.
+ * If the tracer is not in the state we want, then the count
+ * is guaranteed to be the old count.
+ *
+ * Next the tracer is set to the state we want (disabled or enabled)
+ * then a write memory barrier is used to make sure that
+ * the new state is visible before changing the counter by
+ * one minus the old counter. This guarantees that another CPU
+ * executing this code will see the new state before seeing
+ * the new counter value, and would not do anything if the new
+ * counter is seen.
+ *
+ * Note, there is no synchronization between this and a user
+ * setting the tracing_on file. But we currently don't care
+ * about that.
+ */
+ count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
+ old_count = *count;
+
+ if (old_count <= 0)
+ return;
+
+ /* Make sure we see count before checking tracing state */
+ smp_rmb();
+
+ if (on == !!tracer_tracing_is_on(tr))
+ return;
+
+ if (on)
+ tracer_tracing_on(tr);
+ else
+ tracer_tracing_off(tr);
+
+ /* Make sure tracing state is visible before updating count */
+ smp_wmb();
+
+ *count = old_count - 1;
+}
+
+static void
+ftrace_traceon_count(unsigned long ip, unsigned long parent_ip,
+ struct trace_array *tr, struct ftrace_probe_ops *ops,
+ void *data)
+{
+ update_traceon_count(ops, ip, tr, 1, data);
+}
+
+static void
+ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip,
+ struct trace_array *tr, struct ftrace_probe_ops *ops,
+ void *data)
+{
+ update_traceon_count(ops, ip, tr, 0, data);
+}
+
+static void
+ftrace_traceon(unsigned long ip, unsigned long parent_ip,
+ struct trace_array *tr, struct ftrace_probe_ops *ops,
+ void *data)
+{
+ if (tracer_tracing_is_on(tr))
+ return;
+
+ tracer_tracing_on(tr);
+}
+
+static void
+ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
+ struct trace_array *tr, struct ftrace_probe_ops *ops,
+ void *data)
+{
+ if (!tracer_tracing_is_on(tr))
+ return;
+
+ tracer_tracing_off(tr);
+}
+
+#ifdef CONFIG_UNWINDER_ORC
+/*
+ * Skip 3:
+ *
+ * function_trace_probe_call()
+ * ftrace_ops_assist_func()
+ * ftrace_call()
+ */
+#define FTRACE_STACK_SKIP 3
+#else
+/*
+ * Skip 5:
+ *
+ * __trace_stack()
+ * ftrace_stacktrace()
+ * function_trace_probe_call()
+ * ftrace_ops_assist_func()
+ * ftrace_call()
+ */
+#define FTRACE_STACK_SKIP 5
+#endif
+
+static __always_inline void trace_stack(struct trace_array *tr)
+{
+ unsigned int trace_ctx;
+
+ trace_ctx = tracing_gen_ctx();
+
+ __trace_stack(tr, trace_ctx, FTRACE_STACK_SKIP);
+}
+
+static void
+ftrace_stacktrace(unsigned long ip, unsigned long parent_ip,
+ struct trace_array *tr, struct ftrace_probe_ops *ops,
+ void *data)
+{
+ trace_stack(tr);
+}
+
+static void
+ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
+ struct trace_array *tr, struct ftrace_probe_ops *ops,
+ void *data)
+{
+ struct ftrace_func_mapper *mapper = data;
+ long *count;
+ long old_count;
+ long new_count;
+
+ if (!tracing_is_on())
+ return;
+
+ /* unlimited? */
+ if (!mapper) {
+ trace_stack(tr);
+ return;
+ }
+
+ count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
+
+ /*
+ * Stack traces should only execute the number of times the
+ * user specified in the counter.
+ */
+ do {
+ old_count = *count;
+
+ if (!old_count)
+ return;
+
+ new_count = old_count - 1;
+ new_count = cmpxchg(count, old_count, new_count);
+ if (new_count == old_count)
+ trace_stack(tr);
+
+ if (!tracing_is_on())
+ return;
+
+ } while (new_count != old_count);
+}
+
+static int update_count(struct ftrace_probe_ops *ops, unsigned long ip,
+ void *data)
+{
+ struct ftrace_func_mapper *mapper = data;
+ long *count = NULL;
+
+ if (mapper)
+ count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
+
+ if (count) {
+ if (*count <= 0)
+ return 0;
+ (*count)--;
+ }
+
+ return 1;
+}
+
+static void
+ftrace_dump_probe(unsigned long ip, unsigned long parent_ip,
+ struct trace_array *tr, struct ftrace_probe_ops *ops,
+ void *data)
+{
+ if (update_count(ops, ip, data))
+ ftrace_dump(DUMP_ALL);
+}
+
+/* Only dump the current CPU buffer. */
+static void
+ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip,
+ struct trace_array *tr, struct ftrace_probe_ops *ops,
+ void *data)
+{
+ if (update_count(ops, ip, data))
+ ftrace_dump(DUMP_ORIG);
+}
+
+static int
+ftrace_probe_print(const char *name, struct seq_file *m,
+ unsigned long ip, struct ftrace_probe_ops *ops,
+ void *data)
+{
+ struct ftrace_func_mapper *mapper = data;
+ long *count = NULL;
+
+ seq_printf(m, "%ps:%s", (void *)ip, name);
+
+ if (mapper)
+ count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
+
+ if (count)
+ seq_printf(m, ":count=%ld\n", *count);
+ else
+ seq_puts(m, ":unlimited\n");
+
+ return 0;
+}
+
+static int
+ftrace_traceon_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops,
+ void *data)
+{
+ return ftrace_probe_print("traceon", m, ip, ops, data);
+}
+
+static int
+ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops, void *data)
+{
+ return ftrace_probe_print("traceoff", m, ip, ops, data);
+}
+
+static int
+ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops, void *data)
+{
+ return ftrace_probe_print("stacktrace", m, ip, ops, data);
+}
+
+static int
+ftrace_dump_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops, void *data)
+{
+ return ftrace_probe_print("dump", m, ip, ops, data);
+}
+
+static int
+ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops, void *data)
+{
+ return ftrace_probe_print("cpudump", m, ip, ops, data);
+}
+
+
+static int
+ftrace_count_init(struct ftrace_probe_ops *ops, struct trace_array *tr,
+ unsigned long ip, void *init_data, void **data)
+{
+ struct ftrace_func_mapper *mapper = *data;
+
+ if (!mapper) {
+ mapper = allocate_ftrace_func_mapper();
+ if (!mapper)
+ return -ENOMEM;
+ *data = mapper;
+ }
+
+ return ftrace_func_mapper_add_ip(mapper, ip, init_data);
+}
+
+static void
+ftrace_count_free(struct ftrace_probe_ops *ops, struct trace_array *tr,
+ unsigned long ip, void *data)
+{
+ struct ftrace_func_mapper *mapper = data;
+
+ if (!ip) {
+ free_ftrace_func_mapper(mapper, NULL);
+ return;
+ }
+
+ ftrace_func_mapper_remove_ip(mapper, ip);
+}
+
+static struct ftrace_probe_ops traceon_count_probe_ops = {
+ .func = ftrace_traceon_count,
+ .print = ftrace_traceon_print,
+ .init = ftrace_count_init,
+ .free = ftrace_count_free,
+};
+
+static struct ftrace_probe_ops traceoff_count_probe_ops = {
+ .func = ftrace_traceoff_count,
+ .print = ftrace_traceoff_print,
+ .init = ftrace_count_init,
+ .free = ftrace_count_free,
+};
+
+static struct ftrace_probe_ops stacktrace_count_probe_ops = {
+ .func = ftrace_stacktrace_count,
+ .print = ftrace_stacktrace_print,
+ .init = ftrace_count_init,
+ .free = ftrace_count_free,
+};
+
+static struct ftrace_probe_ops dump_probe_ops = {
+ .func = ftrace_dump_probe,
+ .print = ftrace_dump_print,
+ .init = ftrace_count_init,
+ .free = ftrace_count_free,
+};
+
+static struct ftrace_probe_ops cpudump_probe_ops = {
+ .func = ftrace_cpudump_probe,
+ .print = ftrace_cpudump_print,
+};
+
+static struct ftrace_probe_ops traceon_probe_ops = {
+ .func = ftrace_traceon,
+ .print = ftrace_traceon_print,
+};
+
+static struct ftrace_probe_ops traceoff_probe_ops = {
+ .func = ftrace_traceoff,
+ .print = ftrace_traceoff_print,
+};
+
+static struct ftrace_probe_ops stacktrace_probe_ops = {
+ .func = ftrace_stacktrace,
+ .print = ftrace_stacktrace_print,
+};
+
+static int
+ftrace_trace_probe_callback(struct trace_array *tr,
+ struct ftrace_probe_ops *ops,
+ struct ftrace_hash *hash, char *glob,
+ char *cmd, char *param, int enable)
+{
+ void *count = (void *)-1;
+ char *number;
+ int ret;
+
+ /* hash funcs only work with set_ftrace_filter */
+ if (!enable)
+ return -EINVAL;
+
+ if (glob[0] == '!')
+ return unregister_ftrace_function_probe_func(glob+1, tr, ops);
+
+ if (!param)
+ goto out_reg;
+
+ number = strsep(&param, ":");
+
+ if (!strlen(number))
+ goto out_reg;
+
+ /*
+ * We use the callback data field (which is a pointer)
+ * as our counter.
+ */
+ ret = kstrtoul(number, 0, (unsigned long *)&count);
+ if (ret)
+ return ret;
+
+ out_reg:
+ ret = register_ftrace_function_probe(glob, tr, ops, count);
+
+ return ret < 0 ? ret : 0;
+}
+
+static int
+ftrace_trace_onoff_callback(struct trace_array *tr, struct ftrace_hash *hash,
+ char *glob, char *cmd, char *param, int enable)
+{
+ struct ftrace_probe_ops *ops;
+
+ if (!tr)
+ return -ENODEV;
+
+ /* we register both traceon and traceoff to this callback */
+ if (strcmp(cmd, "traceon") == 0)
+ ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
+ else
+ ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
+
+ return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
+ param, enable);
+}
+
+static int
+ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash,
+ char *glob, char *cmd, char *param, int enable)
+{
+ struct ftrace_probe_ops *ops;
+
+ if (!tr)
+ return -ENODEV;
+
+ ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
+
+ return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
+ param, enable);
+}
+
+static int
+ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash,
+ char *glob, char *cmd, char *param, int enable)
+{
+ struct ftrace_probe_ops *ops;
+
+ if (!tr)
+ return -ENODEV;
+
+ ops = &dump_probe_ops;
+
+ /* Only dump once. */
+ return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
+ "1", enable);
+}
+
+static int
+ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash,
+ char *glob, char *cmd, char *param, int enable)
+{
+ struct ftrace_probe_ops *ops;
+
+ if (!tr)
+ return -ENODEV;
+
+ ops = &cpudump_probe_ops;
+
+ /* Only dump once. */
+ return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
+ "1", enable);
+}
+
+static struct ftrace_func_command ftrace_traceon_cmd = {
+ .name = "traceon",
+ .func = ftrace_trace_onoff_callback,
+};
+
+static struct ftrace_func_command ftrace_traceoff_cmd = {
+ .name = "traceoff",
+ .func = ftrace_trace_onoff_callback,
+};
+
+static struct ftrace_func_command ftrace_stacktrace_cmd = {
+ .name = "stacktrace",
+ .func = ftrace_stacktrace_callback,
+};
+
+static struct ftrace_func_command ftrace_dump_cmd = {
+ .name = "dump",
+ .func = ftrace_dump_callback,
+};
+
+static struct ftrace_func_command ftrace_cpudump_cmd = {
+ .name = "cpudump",
+ .func = ftrace_cpudump_callback,
+};
+
+static int __init init_func_cmd_traceon(void)
+{
+ int ret;
+
+ ret = register_ftrace_command(&ftrace_traceoff_cmd);
+ if (ret)
+ return ret;
+
+ ret = register_ftrace_command(&ftrace_traceon_cmd);
+ if (ret)
+ goto out_free_traceoff;
+
+ ret = register_ftrace_command(&ftrace_stacktrace_cmd);
+ if (ret)
+ goto out_free_traceon;
+
+ ret = register_ftrace_command(&ftrace_dump_cmd);
+ if (ret)
+ goto out_free_stacktrace;
+
+ ret = register_ftrace_command(&ftrace_cpudump_cmd);
+ if (ret)
+ goto out_free_dump;
+
+ return 0;
+
+ out_free_dump:
+ unregister_ftrace_command(&ftrace_dump_cmd);
+ out_free_stacktrace:
+ unregister_ftrace_command(&ftrace_stacktrace_cmd);
+ out_free_traceon:
+ unregister_ftrace_command(&ftrace_traceon_cmd);
+ out_free_traceoff:
+ unregister_ftrace_command(&ftrace_traceoff_cmd);
+
+ return ret;
+}
+#else
+static inline int init_func_cmd_traceon(void)
+{
+ return 0;
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+__init int init_function_trace(void)
+{
+ init_func_cmd_traceon();
+ return register_tracer(&function_trace);
+}