aboutsummaryrefslogtreecommitdiff
path: root/samples/trace_events/trace-events-sample.h
diff options
context:
space:
mode:
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 /samples/trace_events/trace-events-sample.h
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 'samples/trace_events/trace-events-sample.h')
-rw-r--r--samples/trace_events/trace-events-sample.h626
1 files changed, 626 insertions, 0 deletions
diff --git a/samples/trace_events/trace-events-sample.h b/samples/trace_events/trace-events-sample.h
new file mode 100644
index 000000000..1c6b843b8
--- /dev/null
+++ b/samples/trace_events/trace-events-sample.h
@@ -0,0 +1,626 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * If TRACE_SYSTEM is defined, that will be the directory created
+ * in the ftrace directory under /sys/kernel/tracing/events/<system>
+ *
+ * The define_trace.h below will also look for a file name of
+ * TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here.
+ * In this case, it would look for sample-trace.h
+ *
+ * If the header name will be different than the system name
+ * (as in this case), then you can override the header name that
+ * define_trace.h will look up by defining TRACE_INCLUDE_FILE
+ *
+ * This file is called trace-events-sample.h but we want the system
+ * to be called "sample-trace". Therefore we must define the name of this
+ * file:
+ *
+ * #define TRACE_INCLUDE_FILE trace-events-sample
+ *
+ * As we do an the bottom of this file.
+ *
+ * Notice that TRACE_SYSTEM should be defined outside of #if
+ * protection, just like TRACE_INCLUDE_FILE.
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sample-trace
+
+/*
+ * TRACE_SYSTEM is expected to be a C valid variable (alpha-numeric
+ * and underscore), although it may start with numbers. If for some
+ * reason it is not, you need to add the following lines:
+ */
+#undef TRACE_SYSTEM_VAR
+#define TRACE_SYSTEM_VAR sample_trace
+/*
+ * But the above is only needed if TRACE_SYSTEM is not alpha-numeric
+ * and underscored. By default, TRACE_SYSTEM_VAR will be equal to
+ * TRACE_SYSTEM. As TRACE_SYSTEM_VAR must be alpha-numeric, if
+ * TRACE_SYSTEM is not, then TRACE_SYSTEM_VAR must be defined with
+ * only alpha-numeric and underscores.
+ *
+ * The TRACE_SYSTEM_VAR is only used internally and not visible to
+ * user space.
+ */
+
+/*
+ * Notice that this file is not protected like a normal header.
+ * We also must allow for rereading of this file. The
+ *
+ * || defined(TRACE_HEADER_MULTI_READ)
+ *
+ * serves this purpose.
+ */
+#if !defined(_TRACE_EVENT_SAMPLE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_EVENT_SAMPLE_H
+
+/*
+ * All trace headers should include tracepoint.h, until we finally
+ * make it into a standard header.
+ */
+#include <linux/tracepoint.h>
+
+/*
+ * The TRACE_EVENT macro is broken up into 5 parts.
+ *
+ * name: name of the trace point. This is also how to enable the tracepoint.
+ * A function called trace_foo_bar() will be created.
+ *
+ * proto: the prototype of the function trace_foo_bar()
+ * Here it is trace_foo_bar(char *foo, int bar).
+ *
+ * args: must match the arguments in the prototype.
+ * Here it is simply "foo, bar".
+ *
+ * struct: This defines the way the data will be stored in the ring buffer.
+ * The items declared here become part of a special structure
+ * called "__entry", which can be used in the fast_assign part of the
+ * TRACE_EVENT macro.
+ *
+ * Here are the currently defined types you can use:
+ *
+ * __field : Is broken up into type and name. Where type can be any
+ * primitive type (integer, long or pointer).
+ *
+ * __field(int, foo)
+ *
+ * __entry->foo = 5;
+ *
+ * __field_struct : This can be any static complex data type (struct, union
+ * but not an array). Be careful using complex types, as each
+ * event is limited in size, and copying large amounts of data
+ * into the ring buffer can slow things down.
+ *
+ * __field_struct(struct bar, foo)
+ *
+ * __entry->bar.x = y;
+
+ * __array: There are three fields (type, name, size). The type is the
+ * type of elements in the array, the name is the name of the array.
+ * size is the number of items in the array (not the total size).
+ *
+ * __array( char, foo, 10) is the same as saying: char foo[10];
+ *
+ * Assigning arrays can be done like any array:
+ *
+ * __entry->foo[0] = 'a';
+ *
+ * memcpy(__entry->foo, bar, 10);
+ *
+ * __dynamic_array: This is similar to array, but can vary its size from
+ * instance to instance of the tracepoint being called.
+ * Like __array, this too has three elements (type, name, size);
+ * type is the type of the element, name is the name of the array.
+ * The size is different than __array. It is not a static number,
+ * but the algorithm to figure out the length of the array for the
+ * specific instance of tracepoint. Again, size is the number of
+ * items in the array, not the total length in bytes.
+ *
+ * __dynamic_array( int, foo, bar) is similar to: int foo[bar];
+ *
+ * Note, unlike arrays, you must use the __get_dynamic_array() macro
+ * to access the array.
+ *
+ * memcpy(__get_dynamic_array(foo), bar, 10);
+ *
+ * Notice, that "__entry" is not needed here.
+ *
+ * __string: This is a special kind of __dynamic_array. It expects to
+ * have a null terminated character array passed to it (it allows
+ * for NULL too, which would be converted into "(null)"). __string
+ * takes two parameter (name, src), where name is the name of
+ * the string saved, and src is the string to copy into the
+ * ring buffer.
+ *
+ * __string(foo, bar) is similar to: strcpy(foo, bar)
+ *
+ * To assign a string, use the helper macro __assign_str().
+ *
+ * __assign_str(foo, bar);
+ *
+ * In most cases, the __assign_str() macro will take the same
+ * parameters as the __string() macro had to declare the string.
+ *
+ * __vstring: This is similar to __string() but instead of taking a
+ * dynamic length, it takes a variable list va_list 'va' variable.
+ * Some event callers already have a message from parameters saved
+ * in a va_list. Passing in the format and the va_list variable
+ * will save just enough on the ring buffer for that string.
+ * Note, the va variable used is a pointer to a va_list, not
+ * to the va_list directly.
+ *
+ * (va_list *va)
+ *
+ * __vstring(foo, fmt, va) is similar to: vsnprintf(foo, fmt, va)
+ *
+ * To assign the string, use the helper macro __assign_vstr().
+ *
+ * __assign_vstr(foo, fmt, va);
+ *
+ * In most cases, the __assign_vstr() macro will take the same
+ * parameters as the __vstring() macro had to declare the string.
+ * Use __get_str() to retrieve the __vstring() just like it would for
+ * __string().
+ *
+ * __string_len: This is a helper to a __dynamic_array, but it understands
+ * that the array has characters in it, and with the combined
+ * use of __assign_str_len(), it will allocate 'len' + 1 bytes
+ * in the ring buffer and add a '\0' to the string. This is
+ * useful if the string being saved has no terminating '\0' byte.
+ * It requires that the length of the string is known as it acts
+ * like a memcpy().
+ *
+ * Declared with:
+ *
+ * __string_len(foo, bar, len)
+ *
+ * To assign this string, use the helper macro __assign_str_len().
+ *
+ * __assign_str_len(foo, bar, len);
+ *
+ * Then len + 1 is allocated to the ring buffer, and a nul terminating
+ * byte is added. This is similar to:
+ *
+ * memcpy(__get_str(foo), bar, len);
+ * __get_str(foo)[len] = 0;
+ *
+ * The advantage of using this over __dynamic_array, is that it
+ * takes care of allocating the extra byte on the ring buffer
+ * for the '\0' terminating byte, and __get_str(foo) can be used
+ * in the TP_printk().
+ *
+ * __bitmask: This is another kind of __dynamic_array, but it expects
+ * an array of longs, and the number of bits to parse. It takes
+ * two parameters (name, nr_bits), where name is the name of the
+ * bitmask to save, and the nr_bits is the number of bits to record.
+ *
+ * __bitmask(target_cpu, nr_cpumask_bits)
+ *
+ * To assign a bitmask, use the __assign_bitmask() helper macro.
+ *
+ * __assign_bitmask(target_cpus, cpumask_bits(bar), nr_cpumask_bits);
+ *
+ * __cpumask: This is pretty much the same as __bitmask but is specific for
+ * CPU masks. The type displayed to the user via the format files will
+ * be "cpumaks_t" such that user space may deal with them differently
+ * if they choose to do so, and the bits is always set to nr_cpumask_bits.
+ *
+ * __cpumask(target_cpu)
+ *
+ * To assign a cpumask, use the __assign_cpumask() helper macro.
+ *
+ * __assign_cpumask(target_cpus, cpumask_bits(bar));
+ *
+ * fast_assign: This is a C like function that is used to store the items
+ * into the ring buffer. A special variable called "__entry" will be the
+ * structure that points into the ring buffer and has the same fields as
+ * described by the struct part of TRACE_EVENT above.
+ *
+ * printk: This is a way to print out the data in pretty print. This is
+ * useful if the system crashes and you are logging via a serial line,
+ * the data can be printed to the console using this "printk" method.
+ * This is also used to print out the data from the trace files.
+ * Again, the __entry macro is used to access the data from the ring buffer.
+ *
+ * Note, __dynamic_array, __string, __bitmask and __cpumask require special
+ * helpers to access the data.
+ *
+ * For __dynamic_array(int, foo, bar) use __get_dynamic_array(foo)
+ * Use __get_dynamic_array_len(foo) to get the length of the array
+ * saved. Note, __get_dynamic_array_len() returns the total allocated
+ * length of the dynamic array; __print_array() expects the second
+ * parameter to be the number of elements. To get that, the array length
+ * needs to be divided by the element size.
+ *
+ * For __string(foo, bar) use __get_str(foo)
+ *
+ * For __bitmask(target_cpus, nr_cpumask_bits) use __get_bitmask(target_cpus)
+ *
+ * For __cpumask(target_cpus) use __get_cpumask(target_cpus)
+ *
+ *
+ * Note, that for both the assign and the printk, __entry is the handler
+ * to the data structure in the ring buffer, and is defined by the
+ * TP_STRUCT__entry.
+ */
+
+/*
+ * It is OK to have helper functions in the file, but they need to be protected
+ * from being defined more than once. Remember, this file gets included more
+ * than once.
+ */
+#ifndef __TRACE_EVENT_SAMPLE_HELPER_FUNCTIONS
+#define __TRACE_EVENT_SAMPLE_HELPER_FUNCTIONS
+static inline int __length_of(const int *list)
+{
+ int i;
+
+ if (!list)
+ return 0;
+
+ for (i = 0; list[i]; i++)
+ ;
+ return i;
+}
+
+enum {
+ TRACE_SAMPLE_FOO = 2,
+ TRACE_SAMPLE_BAR = 4,
+ TRACE_SAMPLE_ZOO = 8,
+};
+#endif
+
+/*
+ * If enums are used in the TP_printk(), their names will be shown in
+ * format files and not their values. This can cause problems with user
+ * space programs that parse the format files to know how to translate
+ * the raw binary trace output into human readable text.
+ *
+ * To help out user space programs, any enum that is used in the TP_printk()
+ * should be defined by TRACE_DEFINE_ENUM() macro. All that is needed to
+ * be done is to add this macro with the enum within it in the trace
+ * header file, and it will be converted in the output.
+ */
+
+TRACE_DEFINE_ENUM(TRACE_SAMPLE_FOO);
+TRACE_DEFINE_ENUM(TRACE_SAMPLE_BAR);
+TRACE_DEFINE_ENUM(TRACE_SAMPLE_ZOO);
+
+TRACE_EVENT(foo_bar,
+
+ TP_PROTO(const char *foo, int bar, const int *lst,
+ const char *string, const struct cpumask *mask,
+ const char *fmt, va_list *va),
+
+ TP_ARGS(foo, bar, lst, string, mask, fmt, va),
+
+ TP_STRUCT__entry(
+ __array( char, foo, 10 )
+ __field( int, bar )
+ __dynamic_array(int, list, __length_of(lst))
+ __string( str, string )
+ __bitmask( cpus, num_possible_cpus() )
+ __cpumask( cpum )
+ __vstring( vstr, fmt, va )
+ ),
+
+ TP_fast_assign(
+ strlcpy(__entry->foo, foo, 10);
+ __entry->bar = bar;
+ memcpy(__get_dynamic_array(list), lst,
+ __length_of(lst) * sizeof(int));
+ __assign_str(str, string);
+ __assign_vstr(vstr, fmt, va);
+ __assign_bitmask(cpus, cpumask_bits(mask), num_possible_cpus());
+ __assign_cpumask(cpum, cpumask_bits(mask));
+ ),
+
+ TP_printk("foo %s %d %s %s %s %s (%s) (%s) %s", __entry->foo, __entry->bar,
+
+/*
+ * Notice here the use of some helper functions. This includes:
+ *
+ * __print_symbolic( variable, { value, "string" }, ... ),
+ *
+ * The variable is tested against each value of the { } pair. If
+ * the variable matches one of the values, then it will print the
+ * string in that pair. If non are matched, it returns a string
+ * version of the number (if __entry->bar == 7 then "7" is returned).
+ */
+ __print_symbolic(__entry->bar,
+ { 0, "zero" },
+ { TRACE_SAMPLE_FOO, "TWO" },
+ { TRACE_SAMPLE_BAR, "FOUR" },
+ { TRACE_SAMPLE_ZOO, "EIGHT" },
+ { 10, "TEN" }
+ ),
+
+/*
+ * __print_flags( variable, "delim", { value, "flag" }, ... ),
+ *
+ * This is similar to __print_symbolic, except that it tests the bits
+ * of the value. If ((FLAG & variable) == FLAG) then the string is
+ * printed. If more than one flag matches, then each one that does is
+ * also printed with delim in between them.
+ * If not all bits are accounted for, then the not found bits will be
+ * added in hex format: 0x506 will show BIT2|BIT4|0x500
+ */
+ __print_flags(__entry->bar, "|",
+ { 1, "BIT1" },
+ { 2, "BIT2" },
+ { 4, "BIT3" },
+ { 8, "BIT4" }
+ ),
+/*
+ * __print_array( array, len, element_size )
+ *
+ * This prints out the array that is defined by __array in a nice format.
+ */
+ __print_array(__get_dynamic_array(list),
+ __get_dynamic_array_len(list) / sizeof(int),
+ sizeof(int)),
+ __get_str(str), __get_bitmask(cpus), __get_cpumask(cpum),
+ __get_str(vstr))
+);
+
+/*
+ * There may be a case where a tracepoint should only be called if
+ * some condition is set. Otherwise the tracepoint should not be called.
+ * But to do something like:
+ *
+ * if (cond)
+ * trace_foo();
+ *
+ * Would cause a little overhead when tracing is not enabled, and that
+ * overhead, even if small, is not something we want. As tracepoints
+ * use static branch (aka jump_labels), where no branch is taken to
+ * skip the tracepoint when not enabled, and a jmp is placed to jump
+ * to the tracepoint code when it is enabled, having a if statement
+ * nullifies that optimization. It would be nice to place that
+ * condition within the static branch. This is where TRACE_EVENT_CONDITION
+ * comes in.
+ *
+ * TRACE_EVENT_CONDITION() is just like TRACE_EVENT, except it adds another
+ * parameter just after args. Where TRACE_EVENT has:
+ *
+ * TRACE_EVENT(name, proto, args, struct, assign, printk)
+ *
+ * the CONDITION version has:
+ *
+ * TRACE_EVENT_CONDITION(name, proto, args, cond, struct, assign, printk)
+ *
+ * Everything is the same as TRACE_EVENT except for the new cond. Think
+ * of the cond variable as:
+ *
+ * if (cond)
+ * trace_foo_bar_with_cond();
+ *
+ * Except that the logic for the if branch is placed after the static branch.
+ * That is, the if statement that processes the condition will not be
+ * executed unless that traecpoint is enabled. Otherwise it still remains
+ * a nop.
+ */
+TRACE_EVENT_CONDITION(foo_bar_with_cond,
+
+ TP_PROTO(const char *foo, int bar),
+
+ TP_ARGS(foo, bar),
+
+ TP_CONDITION(!(bar % 10)),
+
+ TP_STRUCT__entry(
+ __string( foo, foo )
+ __field( int, bar )
+ ),
+
+ TP_fast_assign(
+ __assign_str(foo, foo);
+ __entry->bar = bar;
+ ),
+
+ TP_printk("foo %s %d", __get_str(foo), __entry->bar)
+);
+
+int foo_bar_reg(void);
+void foo_bar_unreg(void);
+
+/*
+ * Now in the case that some function needs to be called when the
+ * tracepoint is enabled and/or when it is disabled, the
+ * TRACE_EVENT_FN() serves this purpose. This is just like TRACE_EVENT()
+ * but adds two more parameters at the end:
+ *
+ * TRACE_EVENT_FN( name, proto, args, struct, assign, printk, reg, unreg)
+ *
+ * reg and unreg are functions with the prototype of:
+ *
+ * void reg(void)
+ *
+ * The reg function gets called before the tracepoint is enabled, and
+ * the unreg function gets called after the tracepoint is disabled.
+ *
+ * Note, reg and unreg are allowed to be NULL. If you only need to
+ * call a function before enabling, or after disabling, just set one
+ * function and pass in NULL for the other parameter.
+ */
+TRACE_EVENT_FN(foo_bar_with_fn,
+
+ TP_PROTO(const char *foo, int bar),
+
+ TP_ARGS(foo, bar),
+
+ TP_STRUCT__entry(
+ __string( foo, foo )
+ __field( int, bar )
+ ),
+
+ TP_fast_assign(
+ __assign_str(foo, foo);
+ __entry->bar = bar;
+ ),
+
+ TP_printk("foo %s %d", __get_str(foo), __entry->bar),
+
+ foo_bar_reg, foo_bar_unreg
+);
+
+/*
+ * Each TRACE_EVENT macro creates several helper functions to produce
+ * the code to add the tracepoint, create the files in the trace
+ * directory, hook it to perf, assign the values and to print out
+ * the raw data from the ring buffer. To prevent too much bloat,
+ * if there are more than one tracepoint that uses the same format
+ * for the proto, args, struct, assign and printk, and only the name
+ * is different, it is highly recommended to use the DECLARE_EVENT_CLASS
+ *
+ * DECLARE_EVENT_CLASS() macro creates most of the functions for the
+ * tracepoint. Then DEFINE_EVENT() is use to hook a tracepoint to those
+ * functions. This DEFINE_EVENT() is an instance of the class and can
+ * be enabled and disabled separately from other events (either TRACE_EVENT
+ * or other DEFINE_EVENT()s).
+ *
+ * Note, TRACE_EVENT() itself is simply defined as:
+ *
+ * #define TRACE_EVENT(name, proto, args, tstruct, assign, printk) \
+ * DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, printk); \
+ * DEFINE_EVENT(name, name, proto, args)
+ *
+ * The DEFINE_EVENT() also can be declared with conditions and reg functions:
+ *
+ * DEFINE_EVENT_CONDITION(template, name, proto, args, cond);
+ * DEFINE_EVENT_FN(template, name, proto, args, reg, unreg);
+ */
+DECLARE_EVENT_CLASS(foo_template,
+
+ TP_PROTO(const char *foo, int bar),
+
+ TP_ARGS(foo, bar),
+
+ TP_STRUCT__entry(
+ __string( foo, foo )
+ __field( int, bar )
+ ),
+
+ TP_fast_assign(
+ __assign_str(foo, foo);
+ __entry->bar = bar;
+ ),
+
+ TP_printk("foo %s %d", __get_str(foo), __entry->bar)
+);
+
+/*
+ * Here's a better way for the previous samples (except, the first
+ * example had more fields and could not be used here).
+ */
+DEFINE_EVENT(foo_template, foo_with_template_simple,
+ TP_PROTO(const char *foo, int bar),
+ TP_ARGS(foo, bar));
+
+DEFINE_EVENT_CONDITION(foo_template, foo_with_template_cond,
+ TP_PROTO(const char *foo, int bar),
+ TP_ARGS(foo, bar),
+ TP_CONDITION(!(bar % 8)));
+
+
+DEFINE_EVENT_FN(foo_template, foo_with_template_fn,
+ TP_PROTO(const char *foo, int bar),
+ TP_ARGS(foo, bar),
+ foo_bar_reg, foo_bar_unreg);
+
+/*
+ * Anytime two events share basically the same values and have
+ * the same output, use the DECLARE_EVENT_CLASS() and DEFINE_EVENT()
+ * when ever possible.
+ */
+
+/*
+ * If the event is similar to the DECLARE_EVENT_CLASS, but you need
+ * to have a different output, then use DEFINE_EVENT_PRINT() which
+ * lets you override the TP_printk() of the class.
+ */
+
+DEFINE_EVENT_PRINT(foo_template, foo_with_template_print,
+ TP_PROTO(const char *foo, int bar),
+ TP_ARGS(foo, bar),
+ TP_printk("bar %s %d", __get_str(foo), __entry->bar));
+
+/*
+ * There are yet another __rel_loc dynamic data attribute. If you
+ * use __rel_dynamic_array() and __rel_string() etc. macros, you
+ * can use this attribute. There is no difference from the viewpoint
+ * of functionality with/without 'rel' but the encoding is a bit
+ * different. This is expected to be used with user-space event,
+ * there is no reason that the kernel event use this, but only for
+ * testing.
+ */
+
+TRACE_EVENT(foo_rel_loc,
+
+ TP_PROTO(const char *foo, int bar, unsigned long *mask, const cpumask_t *cpus),
+
+ TP_ARGS(foo, bar, mask, cpus),
+
+ TP_STRUCT__entry(
+ __rel_string( foo, foo )
+ __field( int, bar )
+ __rel_bitmask( bitmask,
+ BITS_PER_BYTE * sizeof(unsigned long) )
+ __rel_cpumask( cpumask )
+ ),
+
+ TP_fast_assign(
+ __assign_rel_str(foo, foo);
+ __entry->bar = bar;
+ __assign_rel_bitmask(bitmask, mask,
+ BITS_PER_BYTE * sizeof(unsigned long));
+ __assign_rel_cpumask(cpumask, cpus);
+ ),
+
+ TP_printk("foo_rel_loc %s, %d, %s, %s", __get_rel_str(foo), __entry->bar,
+ __get_rel_bitmask(bitmask),
+ __get_rel_cpumask(cpumask))
+);
+#endif
+
+/***** NOTICE! The #if protection ends here. *****/
+
+
+/*
+ * There are several ways I could have done this. If I left out the
+ * TRACE_INCLUDE_PATH, then it would default to the kernel source
+ * include/trace/events directory.
+ *
+ * I could specify a path from the define_trace.h file back to this
+ * file.
+ *
+ * #define TRACE_INCLUDE_PATH ../../samples/trace_events
+ *
+ * But the safest and easiest way to simply make it use the directory
+ * that the file is in is to add in the Makefile:
+ *
+ * CFLAGS_trace-events-sample.o := -I$(src)
+ *
+ * This will make sure the current path is part of the include
+ * structure for our file so that define_trace.h can find it.
+ *
+ * I could have made only the top level directory the include:
+ *
+ * CFLAGS_trace-events-sample.o := -I$(PWD)
+ *
+ * And then let the path to this directory be the TRACE_INCLUDE_PATH:
+ *
+ * #define TRACE_INCLUDE_PATH samples/trace_events
+ *
+ * But then if something defines "samples" or "trace_events" as a macro
+ * then we could risk that being converted too, and give us an unexpected
+ * result.
+ */
+#undef TRACE_INCLUDE_PATH
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_PATH .
+/*
+ * TRACE_INCLUDE_FILE is not needed if the filename and TRACE_SYSTEM are equal
+ */
+#define TRACE_INCLUDE_FILE trace-events-sample
+#include <trace/define_trace.h>