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.

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

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tracing: mark user_events as BROKEN

After being merged, user_events become more visible to a wider audience
that have concerns with the current API.

It is too late to fix this for this release, but

tracing: mark user_events as BROKEN

After being merged, user_events become more visible to a wider audience
that have concerns with the current API.

It is too late to fix this for this release, but instead of a full
revert, just mark it as BROKEN (which prevents it from being selected in
make config). Then we can work finding a better API. If that fails,
then it will need to be completely reverted.

To not have the code silently bitrot, still allow building it with
COMPILE_TEST.

And to prevent the uapi header from being installed, then later changed,
and then have an old distro user space see the old version, move the
header file out of the uapi directory.

Surround the include with CONFIG_COMPILE_TEST to the current location,
but when the BROKEN tag is taken off, it will use the uapi directory,
and fail to compile. This is a good way to remind us to move the header
back.

Link: https://lore.kernel.org/all/20220330155835.5e1f6669@gandalf.local.home
Link: https://lkml.kernel.org/r/20220330201755.29319-1-mathieu.desnoyers@efficios.com
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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tracing: Move user_events.h temporarily out of include/uapi

While user_events API is under development and has been marked for broken
to not let the API become fixed, move the header file out of the

tracing: Move user_events.h temporarily out of include/uapi

While user_events API is under development and has been marked for broken
to not let the API become fixed, move the header file out of the uapi
directory. This is to prevent it from being installed, then later changed,
and then have an old distro user space update with a new kernel, where
applications see the user_events being available, but the old header is in
place, and then they get compiled incorrectly.

Also, surround the include with CONFIG_COMPILE_TEST to the current
location, but when the BROKEN tag is taken off, it will use the uapi
directory, and fail to compile. This is a good way to remind us to move
the header back.

Link: https://lore.kernel.org/all/20220330155835.5e1f6669@gandalf.local.home
Link: https://lkml.kernel.org/r/20220330201755.29319-1-mathieu.desnoyers@efficios.com
Link: https://lkml.kernel.org/r/20220401143903.188384f3@gandalf.local.home

Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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tracing/user_events: Remove eBPF interfaces

Remove eBPF interfaces within user_events to ensure they are fully
reviewed.

Link: https://lore.kernel.org/all/20220329165718.GA10381@kbox/
Link: https:/

tracing/user_events: Remove eBPF interfaces

Remove eBPF interfaces within user_events to ensure they are fully
reviewed.

Link: https://lore.kernel.org/all/20220329165718.GA10381@kbox/
Link: https://lkml.kernel.org/r/20220329173051.10087-1-beaub@linux.microsoft.com

Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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tracing/user_events: Hold event_mutex during dyn_event_add

Make sure the event_mutex is properly held during dyn_event_add call.
This is required when adding dynamic events.

Link: https://lkml.kern

tracing/user_events: Hold event_mutex during dyn_event_add

Make sure the event_mutex is properly held during dyn_event_add call.
This is required when adding dynamic events.

Link: https://lkml.kernel.org/r/20220328223225.1992-1-beaub@linux.microsoft.com

Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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Merge tag 'trace-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

- New user_events interface. User space can register an event

Merge tag 'trace-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

- New user_events interface. User space can register an event with the
kernel describing the format of the event. Then it will receive a
byte in a page mapping that it can check against. A privileged task
can then enable that event like any other event, which will change
the mapped byte to true, telling the user space application to start
writing the event to the tracing buffer.

- Add new "ftrace_boot_snapshot" kernel command line parameter. When
set, the tracing buffer will be saved in the snapshot buffer at boot
up when the kernel hands things over to user space. This will keep
the traces that happened at boot up available even if user space boot
up has tracing as well.

- Have TRACE_EVENT_ENUM() also update trace event field type
descriptions. Thus if a static array defines its size with an enum,
the user space trace event parsers can still know how to parse that
array.

- Add new TRACE_CUSTOM_EVENT() macro. This acts the same as the
TRACE_EVENT() macro, but will attach to an existing tracepoint. This
will make one tracepoint be able to trace different content and not
be stuck at only what the original TRACE_EVENT() macro exports.

- Fixes to tracing error logging.

- Better saving of cmdlines to PIDs when tracing (use the wakeup events
for mapping).

* tag 'trace-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (30 commits)
tracing: Have type enum modifications copy the strings
user_events: Add trace event call as root for low permission cases
tracing/user_events: Use alloc_pages instead of kzalloc() for register pages
tracing: Add snapshot at end of kernel boot up
tracing: Have TRACE_DEFINE_ENUM affect trace event types as well
tracing: Fix strncpy warning in trace_events_synth.c
user_events: Prevent dyn_event delete racing with ioctl add/delete
tracing: Add TRACE_CUSTOM_EVENT() macro
tracing: Move the defines to create TRACE_EVENTS into their own files
tracing: Add sample code for custom trace events
tracing: Allow custom events to be added to the tracefs directory
tracing: Fix last_cmd_set() string management in histogram code
user_events: Fix potential uninitialized pointer while parsing field
tracing: Fix allocation of last_cmd in last_cmd_set()
user_events: Add documentation file
user_events: Add sample code for typical usage
user_events: Add self-test for validator boundaries
user_events: Add self-test for perf_event integration
user_events: Add self-test for dynamic_events integration
user_events: Add self-test for ftrace integration
...

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user_events: Add trace event call as root for low permission cases

Tracefs by default is locked down heavily. System operators can open up
some files, such as user_events to a broader set of users.

user_events: Add trace event call as root for low permission cases

Tracefs by default is locked down heavily. System operators can open up
some files, such as user_events to a broader set of users. These users
do not have access within tracefs beyond just the user_event files. Due
to this restriction the trace_add_event_call/remove calls will silently
fail since the caller does not have permissions to create directories.

To fix this trace_add_event_call/remove calls will be issued with
override creds of the global root UID. Creds are reverted immediately
afterward.

Link: https://lkml.kernel.org/r/20220308222807.2040-1-beaub@linux.microsoft.com

Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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tracing/user_events: Use alloc_pages instead of kzalloc() for register pages

kzalloc virtual addresses do not work with SetPageReserved, use the actual
page virtual addresses instead via alloc_pages

tracing/user_events: Use alloc_pages instead of kzalloc() for register pages

kzalloc virtual addresses do not work with SetPageReserved, use the actual
page virtual addresses instead via alloc_pages.

The issue is reported when booting with user_events and
DEBUG_VM_PGFLAGS=y.

Also make the number of events based on the ORDER.

Link: https://lore.kernel.org/all/CADYN=9+xY5Vku3Ws5E9S60SM5dCFfeGeRBkmDFbcxX0ZMoFing@mail.gmail.com/
Link: https://lore.kernel.org/all/20220311223028.1865-1-beaub@linux.microsoft.com/

Cc: Beau Belgrave <beaub@linux.microsoft.com>
Reported-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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user_events: Prevent dyn_event delete racing with ioctl add/delete

Find user_events always while under the event_mutex and before leaving
the lock, add a ref count to the user_event. This ensures th

user_events: Prevent dyn_event delete racing with ioctl add/delete

Find user_events always while under the event_mutex and before leaving
the lock, add a ref count to the user_event. This ensures that all paths
under the event_mutex that check the ref counts will be synchronized.

The ioctl add/delete paths are protected by the reg_mutex. However,
dyn_event is only protected by the event_mutex. The dyn_event delete
path cannot acquire reg_mutex, since that could cause a deadlock between
the ioctl delete case acquiring event_mutex after acquiring the reg_mutex.

Link: https://lkml.kernel.org/r/20220310001141.1660-1-beaub@linux.microsoft.com

Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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user_events: Fix potential uninitialized pointer while parsing field

Ensure name is initialized by default to NULL to prevent possible edge
cases that could lead to it being left uninitialized. Add

user_events: Fix potential uninitialized pointer while parsing field

Ensure name is initialized by default to NULL to prevent possible edge
cases that could lead to it being left uninitialized. Add an explicit
check for NULL name to ensure edge boundaries.

Link: https://lore.kernel.org/bpf/20220224105334.GA2248@kili/
Link: https://lore.kernel.org/linux-trace-devel/20220224181637.2129-1-beaub@linux.microsoft.com

Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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user_events: Validate user payloads for size and null termination

Add validation to ensure data is at or greater than the min size for the
fields of the event. If a dynamic array is used and is a ty

user_events: Validate user payloads for size and null termination

Add validation to ensure data is at or greater than the min size for the
fields of the event. If a dynamic array is used and is a type of char,
ensure null termination of the array exists.

Link: https://lkml.kernel.org/r/20220118204326.2169-7-beaub@linux.microsoft.com

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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user_events: Optimize writing events by only copying data once

Pass iterator through to probes to allow copying data directly to the
probe buffers instead of taking multiple copies. Enables eBPF use

user_events: Optimize writing events by only copying data once

Pass iterator through to probes to allow copying data directly to the
probe buffers instead of taking multiple copies. Enables eBPF user and
raw iterator types out to programs for no-copy scenarios.

Link: https://lkml.kernel.org/r/20220118204326.2169-6-beaub@linux.microsoft.com

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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user_events: Add basic perf and eBPF support

Adds support to write out user_event data to perf_probe/perf files as
well as to any attached eBPF program.

Link: https://lkml.kernel.org/r/202201182043

user_events: Add basic perf and eBPF support

Adds support to write out user_event data to perf_probe/perf files as
well as to any attached eBPF program.

Link: https://lkml.kernel.org/r/20220118204326.2169-5-beaub@linux.microsoft.com

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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user_events: Handle matching arguments from dyn_events

Ensures that when dynamic events requests a match with arguments that
they match what is in the user_event.

Link: https://lkml.kernel.org/r/20

user_events: Handle matching arguments from dyn_events

Ensures that when dynamic events requests a match with arguments that
they match what is in the user_event.

Link: https://lkml.kernel.org/r/20220118204326.2169-4-beaub@linux.microsoft.com

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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user_events: Add print_fmt generation support for basic types

Addes print_fmt format generation for basic types that are supported for
user processes. Only supports sizes that are the same on 32 and

user_events: Add print_fmt generation support for basic types

Addes print_fmt format generation for basic types that are supported for
user processes. Only supports sizes that are the same on 32 and 64 bit.

Link: https://lkml.kernel.org/r/20220118204326.2169-3-beaub@linux.microsoft.com

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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user_events: Add minimal support for trace_event into ftrace

Minimal support for interacting with dynamic events, trace_event and
ftrace. Core outline of flow between user process, ioctl and trace_e

user_events: Add minimal support for trace_event into ftrace

Minimal support for interacting with dynamic events, trace_event and
ftrace. Core outline of flow between user process, ioctl and trace_event
APIs.

User mode processes that wish to use trace events to get data into
ftrace, perf, eBPF, etc are limited to uprobes today. The user events
features enables an ABI for user mode processes to create and write to
trace events that are isolated from kernel level trace events. This
enables a faster path for tracing from user mode data as well as opens
managed code to participate in trace events, where stub locations are
dynamic.

User processes often want to trace only when it's useful. To enable this
a set of pages are mapped into the user process space that indicate the
current state of the user events that have been registered. User
processes can check if their event is hooked to a trace/probe, and if it
is, emit the event data out via the write() syscall.

Two new files are introduced into tracefs to accomplish this:
user_events_status - This file is mmap'd into participating user mode
processes to indicate event status.

user_events_data - This file is opened and register/delete ioctl's are
issued to create/open/delete trace events that can be used for tracing.

The typical scenario is on process start to mmap user_events_status. Processes
then register the events they plan to use via the REG ioctl. The ioctl reads
and updates the passed in user_reg struct. The status_index of the struct is
used to know the byte in the status page to check for that event. The
write_index of the struct is used to describe that event when writing out to
the fd that was used for the ioctl call. The data must always include this
index first when writing out data for an event. Data can be written either by
write() or by writev().

For example, in memory:
int index;
char data[];

Psuedo code example of typical usage:
struct user_reg reg;

int page_fd = open("user_events_status", O_RDWR);
char *page_data = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_SHARED, page_fd, 0);
close(page_fd);

int data_fd = open("user_events_data", O_RDWR);

reg.size = sizeof(reg);
reg.name_args = (__u64)"test";

ioctl(data_fd, DIAG_IOCSREG, &reg);
int status_id = reg.status_index;
int write_id = reg.write_index;

struct iovec io[2];
io[0].iov_base = &write_id;
io[0].iov_len = sizeof(write_id);
io[1].iov_base = payload;
io[1].iov_len = sizeof(payload);

if (page_data[status_id])
writev(data_fd, io, 2);

User events are also exposed via the dynamic_events tracefs file for
both create and delete. Current status is exposed via the user_events_status
tracefs file.

Simple example to register a user event via dynamic_events:
echo u:test >> dynamic_events
cat dynamic_events
u:test

If an event is hooked to a probe, the probe hooked shows up:
echo 1 > events/user_events/test/enable
cat user_events_status
1:test # Used by ftrace

Active: 1
Busy: 1
Max: 4096

If an event is not hooked to a probe, no probe status shows up:
echo 0 > events/user_events/test/enable
cat user_events_status
1:test

Active: 1
Busy: 0
Max: 4096

Users can describe the trace event format via the following format:
name[:FLAG1[,FLAG2...] [field1[;field2...]]

Each field has the following format:
type name

Example for char array with a size of 20 named msg:
echo 'u:detailed char[20] msg' >> dynamic_events
cat dynamic_events
u:detailed char[20] msg

Data offsets are based on the data written out via write() and will be
updated to reflect the correct offset in the trace_event fields. For dynamic
data it is recommended to use the new __rel_loc data type. This type will be
the same as __data_loc, but the offset is relative to this entry. This allows
user_events to not worry about what common fields are being inserted before
the data.

The above format is valid for both the ioctl and the dynamic_events file.

Link: https://lkml.kernel.org/r/20220118204326.2169-2-beaub@linux.microsoft.com

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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