wireguard-linux/kernel/trace/trace_events_synth.c, branch jd/orphan-parallel

tracing: support "bool" type in synthetic trace events

2020-10-15T16:01:14Z

It's common [1] to define tracepoint fields as "bool" when they contain a true / false value. Currently, defining a synthetic event with a "bool" field yields EINVAL. It's possible to work around this by using e.g. u8 (assuming sizeof(bool) is 1, and bool is unsigned; if either of these properties don't match, you get EINVAL [2]). Supporting "bool" explicitly makes hooking this up easier and more portable for userspace. [1]: grep -r "bool" include/trace/events/ [2]: check_synth_field() in kernel/trace/trace_events_hist.c Link: https://lkml.kernel.org/r/20201009220524.485102-2-axelrasmussen@google.com Acked-by: Michel Lespinasse Acked-by: David Rientjes Signed-off-by: Axel Rasmussen Signed-off-by: Steven Rostedt (VMware)

tracing: Handle synthetic event array field type checking correctly

2020-10-15T16:01:13Z

Since synthetic event array types are derived from the field name, there may be a semicolon at the end of the type which should be stripped off. If there are more characters following that, normal type string checking will result in an invalid type. Without this patch, you can end up with an invalid field type string that gets displayed in both the synthetic event description and the event format: Before: # echo 'myevent char str[16]; int v' >> synthetic_events # cat synthetic_events myevent char[16]; str; int v name: myevent ID: 1936 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:char str[16];; offset:8; size:16; signed:1; field:int v; offset:40; size:4; signed:1; print fmt: "str=%s, v=%d", REC->str, REC->v After: # echo 'myevent char str[16]; int v' >> synthetic_events # cat synthetic_events myevent char[16] str; int v # cat events/synthetic/myevent/format name: myevent ID: 1936 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:char str[16]; offset:8; size:16; signed:1; field:int v; offset:40; size:4; signed:1; print fmt: "str=%s, v=%d", REC->str, REC->v Link: https://lkml.kernel.org/r/6587663b56c2d45ab9d8c8472a2110713cdec97d.1602598160.git.zanussi@kernel.org [ : wrote parse_synth_field() snippet. ] Fixes: 4b147936fa50 (tracing: Add support for 'synthetic' events) Reported-by: Masami Hiramatsu Tested-by: Masami Hiramatsu Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware)

tracing: Add synthetic event error logging

2020-10-15T16:01:13Z

Add support for synthetic event error logging, which entails adding a logging function for it, a way to save the synthetic event command, and a set of specific synthetic event parse error strings and handling. Link: https://lkml.kernel.org/r/ed099c66df13b40cfc633aaeb17f66c37a923066.1602598160.git.zanussi@kernel.org [ : wrote save_cmdstr() seq_buf implementation. ] Tested-by: Masami Hiramatsu Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware)

tracing: Check that the synthetic event and field names are legal

2020-10-15T16:01:13Z

Call the is_good_name() function used by probe events to make sure synthetic event and field names don't contain illegal characters and cause unexpected parsing of synthetic event commands. Link: https://lkml.kernel.org/r/c4d4bb59d3ac39bcbd70fba0cf837d6b1cedb015.1602598160.git.zanussi@kernel.org Fixes: 4b147936fa50 (tracing: Add support for 'synthetic' events) Reported-by: Masami Hiramatsu Reviewed-by: Masami Hiramatsu Tested-by: Masami Hiramatsu Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware)

tracing: Don't show dynamic string internals in synthetic event description

2020-10-15T16:01:13Z

For synthetic event dynamic fields, the type contains "__data_loc", which is basically an internal part of the type which is only meant to be displayed in the format, not in the event description itself, which is confusing to users since they can't use __data_loc on the command-line to define an event field, which printing it would lead them to believe. So filter it out from the description, while leaving it in the type. Link: https://lkml.kernel.org/r/b3b7baf7813298a5ede4ff02e2e837b91c05a724.1602598160.git.zanussi@kernel.org Reported-by: Masami Hiramatsu Tested-by: Masami Hiramatsu Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware)

tracing: Fix synthetic print fmt check for use of __get_str()

2020-10-08T19:29:07Z

A cut and paste error had the check to use __get_str() test "is_dynamic" twice, instead of checking "is_string && is_dynamic". Link: https://lore.kernel.org/r/d34dccd5-96ba-a2d9-46ea-de8807525deb@canonical.com Reported-by: Colin Ian King Acked-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware)

tracing: Change synthetic event string format to limit printed length

2020-10-08T19:29:06Z

Change the format for printing synthetic field strings to limit the length of the string printed even if it's not correctly terminated. Link: https://lore.kernel.org/r/20201002210036.0200371b@oasis.local.home Link: https://lkml.kernel.org/r/b6bdb34e70d970e8026daa3503db6b8e5cdad524.1601848695.git.zanussi@kernel.org Signed-off-by: Steven Rostedt (VMware)

tracing: Add support for dynamic strings to synthetic events

2020-10-05T23:32:18Z

Currently, sythetic events only support static string fields such as: # echo 'test_latency u64 lat; char somename[32]' > /sys/kernel/debug/tracing/synthetic_events Which is fine, but wastes a lot of space in the event. It also prevents the most commonly-defined strings in the existing trace events e.g. those defined using __string(), from being passed to synthetic events via the trace() action. With this change, synthetic events with dynamic fields can be defined: # echo 'test_latency u64 lat; char somename[]' > /sys/kernel/debug/tracing/synthetic_events And the trace() action can be used to generate events using either dynamic or static strings: # echo 'hist:keys=name:lat=common_timestamp.usecs-$ts0:onmatch(sys.event).test_latency($lat,name)' > /sys/kernel/debug/tracing/events The synthetic event dynamic strings are implemented in the same way as the existing __data_loc strings and appear as such in the format file. [ : added __set_synth_event_print_fmt() changes: I added the following to make it work with trace-cmd. Dynamic strings must have __get_str() for events in the print_fmt otherwise it can't be parsed correctly. ] Link: https://lore.kernel.org/r/cover.1601588066.git.zanussi@kernel.org Link: https://lkml.kernel.org/r/3ed35b6d0e390f5b94cb4a9ba1cc18f5982ab277.1601848695.git.zanussi@kernel.org Tested-by: Axel Rasmussen Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware)

tracing: Fix parse_synth_field() error handling

2020-10-05T22:13:53Z

synth_field_size() returns either a positive size or an error (zero or a negative value). However, the existing code assumes the only error value is 0. It doesn't handle negative error codes, as it assigns directly to field->size (a size_t; unsigned), thereby interpreting the error code as a valid size instead. Do the test before assignment to field->size. [ axelrasmussen@google.com: changelog addition, first paragraph above ] Link: https://lkml.kernel.org/r/9b6946d9776b2eeb43227678158196de1c3c6e1d.1601848695.git.zanussi@kernel.org Fixes: 4b147936fa50 (tracing: Add support for 'synthetic' events) Reviewed-by: Masami Hiramatsu Tested-by: Axel Rasmussen Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware)

tracing/boot, kprobe, synth: Initialize boot-time tracing earlier

2020-09-22T01:06:04Z

Initialize boot-time tracing in core_initcall_sync instead of fs_initcall, and initialize required tracers (kprobes and synth) in core_initcall. This will allow the boot-time tracing to trace __init code from the beginning of postcore_initcall stage. Link: https://lkml.kernel.org/r/159974155727.478751.7486926132902849578.stgit@devnote2 Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)