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authorLinus Torvalds <torvalds@linux-foundation.org>2022-04-03 12:26:01 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-04-03 12:26:01 -0700
commit09bb8856d4a7cf3128dedd79cd07d75bbf4a9f04 (patch)
treed0ae1e3042793fe397ad65f5fdb05bde32de31e9 /Documentation
parent34a53ff911eb30629baad788fbed892f711bdd3e (diff)
parent5cfff569cab8bf544bab62c911c5d6efd5af5e05 (diff)
Merge tag 'trace-v5.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull more tracing updates from Steven Rostedt: - Rename the staging files to give them some meaning. Just stage1,stag2,etc, does not show what they are for - Check for NULL from allocation in bootconfig - Hold event mutex for dyn_event call in user events - Mark user events to broken (to work on the API) - Remove eBPF updates from user events - Remove user events from uapi header to keep it from being installed. - Move ftrace_graph_is_dead() into inline as it is called from hot paths and also convert it into a static branch. * tag 'trace-v5.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Move user_events.h temporarily out of include/uapi ftrace: Make ftrace_graph_is_dead() a static branch tracing: Set user_events to BROKEN tracing/user_events: Remove eBPF interfaces tracing/user_events: Hold event_mutex during dyn_event_add proc: bootconfig: Add null pointer check tracing: Rename the staging files for trace_events
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/trace/user_events.rst14
1 files changed, 3 insertions, 11 deletions
diff --git a/Documentation/trace/user_events.rst b/Documentation/trace/user_events.rst
index bddedabaca80..c180936f49fc 100644
--- a/Documentation/trace/user_events.rst
+++ b/Documentation/trace/user_events.rst
@@ -7,7 +7,7 @@ user_events: User-based Event Tracing
Overview
--------
User based trace events allow user processes to create events and trace data
-that can be viewed via existing tools, such as ftrace, perf and eBPF.
+that can be viewed via existing tools, such as ftrace and perf.
To enable this feature, build your kernel with CONFIG_USER_EVENTS=y.
Programs can view status of the events via
@@ -67,8 +67,7 @@ The command string format is as follows::
Supported Flags
^^^^^^^^^^^^^^^
-**BPF_ITER** - EBPF programs attached to this event will get the raw iovec
-struct instead of any data copies for max performance.
+None yet
Field Format
^^^^^^^^^^^^
@@ -160,7 +159,7 @@ The following values are defined to aid in checking what has been attached:
**EVENT_STATUS_FTRACE** - Bit set if ftrace has been attached (Bit 0).
-**EVENT_STATUS_PERF** - Bit set if perf/eBPF has been attached (Bit 1).
+**EVENT_STATUS_PERF** - Bit set if perf has been attached (Bit 1).
Writing Data
------------
@@ -204,13 +203,6 @@ It's advised for user programs to do the following::
**NOTE:** *The write_index is not emitted out into the trace being recorded.*
-EBPF
-----
-EBPF programs that attach to a user-based event tracepoint are given a pointer
-to a struct user_bpf_context. The bpf context contains the data type (which can
-be a user or kernel buffer, or can be a pointer to the iovec) and the data
-length that was emitted (minus the write_index).
-
Example Code
------------
See sample code in samples/user_events.