linux/kernel/trace/trace_events_trigger.c, branch v5.17

tracing: Uninline trace_trigger_soft_disabled() partly

2022-02-25T17:07:01Z

On a powerpc32 build with CONFIG_CC_OPTIMISE_FOR_SIZE, the inline keyword is not honored and trace_trigger_soft_disabled() appears approx 50 times in vmlinux. Adding -Winline to the build, the following message appears: ./include/linux/trace_events.h:712:1: error: inlining failed in call to 'trace_trigger_soft_disabled': call is unlikely and code size would grow [-Werror=inline] That function is rather big for an inlined function: c003df60 : c003df60: 94 21 ff f0 stwu r1,-16(r1) c003df64: 7c 08 02 a6 mflr r0 c003df68: 90 01 00 14 stw r0,20(r1) c003df6c: bf c1 00 08 stmw r30,8(r1) c003df70: 83 e3 00 24 lwz r31,36(r3) c003df74: 73 e9 01 00 andi. r9,r31,256 c003df78: 41 82 00 10 beq c003df88 c003df7c: 38 60 00 00 li r3,0 c003df80: 39 61 00 10 addi r11,r1,16 c003df84: 4b fd 60 ac b c0014030 <_rest32gpr_30_x> c003df88: 73 e9 00 80 andi. r9,r31,128 c003df8c: 7c 7e 1b 78 mr r30,r3 c003df90: 41 a2 00 14 beq c003dfa4 c003df94: 38 c0 00 00 li r6,0 c003df98: 38 a0 00 00 li r5,0 c003df9c: 38 80 00 00 li r4,0 c003dfa0: 48 05 c5 f1 bl c009a590 c003dfa4: 73 e9 00 40 andi. r9,r31,64 c003dfa8: 40 82 00 28 bne c003dfd0 c003dfac: 73 ff 02 00 andi. r31,r31,512 c003dfb0: 41 82 ff cc beq c003df7c c003dfb4: 80 01 00 14 lwz r0,20(r1) c003dfb8: 83 e1 00 0c lwz r31,12(r1) c003dfbc: 7f c3 f3 78 mr r3,r30 c003dfc0: 83 c1 00 08 lwz r30,8(r1) c003dfc4: 7c 08 03 a6 mtlr r0 c003dfc8: 38 21 00 10 addi r1,r1,16 c003dfcc: 48 05 6f 6c b c0094f38 c003dfd0: 38 60 00 01 li r3,1 c003dfd4: 4b ff ff ac b c003df80 However it is located in a hot path so inlining it is important. But forcing inlining of the entire function by using __always_inline leads to increasing the text size by approx 20 kbytes. Instead, split the fonction in two parts, one part with the likely fast path, flagged __always_inline, and a second part out of line. With this change, on a powerpc32 with CONFIG_CC_OPTIMISE_FOR_SIZE vmlinux text increases by only 1,4 kbytes, which is partly compensated by a decrease of vmlinux data by 7 kbytes. On ppc64_defconfig which has CONFIG_CC_OPTIMISE_FOR_SPEED, this change reduces vmlinux text by more than 30 kbytes. Link: https://lkml.kernel.org/r/69ce0986a52d026d381d612801d978aa4f977460.1644563295.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy Signed-off-by: Steven Rostedt (Google)

tracing: Have traceon and traceoff trigger honor the instance

2022-02-25T17:06:45Z

If a trigger is set on an event to disable or enable tracing within an instance, then tracing should be disabled or enabled in the instance and not at the top level, which is confusing to users. Link: https://lkml.kernel.org/r/20220223223837.14f94ec3@rorschach.local.home Cc: stable@vger.kernel.org Fixes: ae63b31e4d0e2 ("tracing: Separate out trace events from global variables") Tested-by: Daniel Bristot de Oliveira Reviewed-by: Tom Zanussi Signed-off-by: Steven Rostedt (Google)

tracing: Dump stacktrace trigger to the corresponding instance

2022-02-25T03:07:03Z

The stacktrace event trigger is not dumping the stacktrace to the instance where it was enabled, but to the global "instance." Use the private_data, pointing to the trigger file, to figure out the corresponding trace instance, and use it in the trigger action, like snapshot_trigger does. Link: https://lkml.kernel.org/r/afbb0b4f18ba92c276865bc97204d438473f4ebc.1645396236.git.bristot@kernel.org Cc: stable@vger.kernel.org Fixes: ae63b31e4d0e2 ("tracing: Separate out trace events from global variables") Reviewed-by: Tom Zanussi Tested-by: Tom Zanussi Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google)

tracing: Add helper functions to simplify event_command.parse() callback handling

2022-01-10T16:09:11Z

The event_command.parse() callback is responsible for parsing and registering triggers. The existing command implementions for this callback duplicate a lot of the same code, so to clean up and consolidate those implementations, introduce a handful of helper functions for implementors to use. This also makes it easier for new commands to be implemented and allows them to focus more on the customizations they provide rather than obscuring and complicating it with boilerplate code. Link: https://lkml.kernel.org/r/c1ff71f594d45177706571132bd3119491097221.1641823001.git.zanussi@kernel.org Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt

tracing: Remove ops param from event_command reg()/unreg() callbacks

2022-01-10T16:09:11Z

The event_trigger_ops for an event_command are already accessible via event_trigger_data.ops so remove the redundant ops from the callback. Link: https://lkml.kernel.org/r/4c6f2a41820452f9cacddc7634ad442928aa2aa6.1641823001.git.zanussi@kernel.org Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt

tracing: Change event_trigger_ops func() to trigger()

2022-01-10T16:09:10Z

The name of the func() callback on event_trigger_ops is too generic and is easily confused with other callbacks with that name, so change it to something that reflects its actual purpose. In this case, the main purpose of the callback is to implement an event trigger, so call it trigger() instead. Also add some more documentation to event_trigger_ops describing the callbacks a bit better. Link: https://lkml.kernel.org/r/36ab812e3ee74ee03ae0043fda41a858ee728c00.1641823001.git.zanussi@kernel.org Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt

tracing: Change event_command func() to parse()

2022-01-10T16:09:10Z

The name of the func() callback on event_command is too generic and is easily confused with other callbacks with that name, so change it to something that reflects its actual purpose. In this case, the main purpose of the callback is to parse an event command, so call it parse() instead. Link: https://lkml.kernel.org/r/7784e321840752ed88aac0b349c0c685fc9247b1.1641823001.git.zanussi@kernel.org Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt

tracing: Add a probe that attaches to trace events

2021-08-20T18:18:40Z

A new dynamic event is introduced: event probe. The event is attached to an existing tracepoint and uses its fields as arguments. The user can specify custom format string of the new event, select what tracepoint arguments will be printed and how to print them. An event probe is created by writing configuration string in 'dynamic_events' ftrace file: e[:[SNAME/]ENAME] SYSTEM/EVENT [FETCHARGS] - Set an event probe -:SNAME/ENAME - Delete an event probe Where: SNAME - System name, if omitted 'eprobes' is used. ENAME - Name of the new event in SNAME, if omitted the SYSTEM_EVENT is used. SYSTEM - Name of the system, where the tracepoint is defined, mandatory. EVENT - Name of the tracepoint event in SYSTEM, mandatory. FETCHARGS - Arguments: =$[:TYPE] - Fetch given filed of the tracepoint and print it as given TYPE with given name. Supported types are: (u8/u16/u32/u64/s8/s16/s32/s64), basic type (x8/x16/x32/x64), hexadecimal types "string", "ustring" and bitfield. Example, attach an event probe on openat system call and print name of the file that will be opened: echo "e:esys/eopen syscalls/sys_enter_openat file=\$filename:string" >> dynamic_events A new dynamic event is created in events/esys/eopen/ directory. It can be deleted with: echo "-:esys/eopen" >> dynamic_events Filters, triggers and histograms can be attached to the new event, it can be matched in synthetic events. There is one limitation - an event probe can not be attached to kprobe, uprobe or another event probe. Link: https://lkml.kernel.org/r/20210812145805.2292326-1-tz.stoyanov@gmail.com Link: https://lkml.kernel.org/r/20210819152825.142428383@goodmis.org Acked-by: Masami Hiramatsu Co-developed-by: Steven Rostedt (VMware) Signed-off-by: Tzvetomir Stoyanov (VMware) Signed-off-by: Steven Rostedt (VMware)

tracing: Have dynamic events have a ref counter

2021-08-18T22:13:47Z

As dynamic events are not created by modules, if something is attached to one, calling "try_module_get()" on its "mod" field, is not going to keep the dynamic event from going away. Since dynamic events do not need the "mod" pointer of the event structure, make a union out of it in order to save memory (there's one structure for each of the thousand+ events in the kernel), and have any event with the DYNAMIC flag set to use a ref counter instead. Link: https://lore.kernel.org/linux-trace-devel/20210813004448.51c7de69ce432d338f4d226b@kernel.org/ Link: https://lkml.kernel.org/r/20210817035027.174869074@goodmis.org Suggested-by: Masami Hiramatsu Acked-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing: Fix set_named_trigger_data() kernel-doc comment

2021-06-10T15:16:20Z

Fix the description of the parameters. Link: https://lkml.kernel.org/r/20210515105735.52785-1-hqjagain@gmail.com Signed-off-by: Qiujun Huang Signed-off-by: Steven Rostedt (VMware)