tracing/synthetic: Fix trace_string() return value

Fix trace_string() by assigning the string length to the return variable
which got lost in commit ddeea494a16f ("tracing/synthetic: Use union
instead of casts") and caused trace_string() to always return 0.

Link: https://lore.kernel.org/linux-trace-kernel/20240214220555.711598-1-thorsten.blum@toblux.com

Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: ddeea494a16f ("tracing/synthetic: Use union instead of casts")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing/synthetic: fix kernel-doc warnings

scripts/kernel-doc warns about using @args: for variadic arguments to
functions. Documentation/doc-guide/kernel-doc.rst says that this should
be written as @...: instead, so update the source code to match that,
preventing the warnings.

trace_events_synth.c:1165: warning: Excess function parameter 'args' description in '__synth_event_gen_cmd_start'
trace_events_synth.c:1714: warning: Excess function parameter 'args' description in 'synth_event_trace'

Link: https://lore.kernel.org/linux-trace-kernel/20231220061226.30962-1-rdunlap@infradead.org

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: 35ca5207c2d11 ("tracing: Add synthetic event command generation functions")
Fixes: 8dcc53ad956d2 ("tracing: Add synth_event_trace() and related functions")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing: Have the user copy of synthetic event address use correct context

A synthetic event is created by the synthetic event interface that can
read both user or kernel address memory. In reality, it reads any
arbitrary memory location from within the kernel. If the address space is
in USER (where CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE is set) then
it uses strncpy_from_user_nofault() to copy strings otherwise it uses
strncpy_from_kernel_nofault().

But since both functions use the same variable there's no annotation to
what that variable is (ie. __user). This makes sparse complain.

Quiet sparse by typecasting the strncpy_from_user_nofault() variable to
a __user pointer.

Link: https://lore.kernel.org/linux-trace-kernel/20231031151033.73c42e23@gandalf.local.home

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: 0934ae9977c2 ("tracing: Fix reading strings from synthetic events");
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311010013.fm8WTxa5-lkp@intel.com/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing/synthetic: Print out u64 values properly

The synth traces incorrectly print pointer to the synthetic event values
instead of the actual value when using u64 type. Fix by addressing the
contents of the union properly.

Link: https://lore.kernel.org/linux-trace-kernel/20230911141704.3585965-1-tero.kristo@linux.intel.com

Fixes: ddeea494a16f ("tracing/synthetic: Use union instead of casts")
Cc: stable@vger.kernel.org
Signed-off-by: Tero Kristo <tero.kristo@linux.intel.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing/synthetic: Allocate one additional element for size

While debugging another issue I noticed that the stack trace contains one
invalid entry at the end:

<idle>-0 [008] d..4. 26.484201: wake_lat: pid=0 delta=2629976084 000000009cc24024 stack=STACK:
=> __schedule+0xac6/0x1a98
=> schedule+0x126/0x2c0
=> schedule_timeout+0x150/0x2c0
=> kcompactd+0x9ca/0xc20
=> kthread+0x2f6/0x3d8
=> __ret_from_fork+0x8a/0xe8
=> 0x6b6b6b6b6b6b6b6b

This is because the code failed to add the one element containing the
number of entries to field_size.

Link: https://lkml.kernel.org/r/20230816154928.4171614-4-svens@linux.ibm.com

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing/synthetic: Skip first entry for stack traces

While debugging another issue I noticed that the stack trace output
contains the number of entries on top:

<idle>-0 [000] d..4. 203.322502: wake_lat: pid=0 delta=2268270616 stack=STACK:
=> 0x10
=> __schedule+0xac6/0x1a98
=> schedule+0x126/0x2c0
=> schedule_timeout+0x242/0x2c0
=> __wait_for_common+0x434/0x680
=> __wait_rcu_gp+0x198/0x3e0
=> synchronize_rcu+0x112/0x138
=> ring_buffer_reset_online_cpus+0x140/0x2e0
=> tracing_reset_online_cpus+0x15c/0x1d0
=> tracing_set_clock+0x180/0x1d8
=> hist_register_trigger+0x486/0x670
=> event_hist_trigger_parse+0x494/0x1318
=> trigger_process_regex+0x1d4/0x258
=> event_trigger_write+0xb4/0x170
=> vfs_write+0x210/0xad0
=> ksys_write+0x122/0x208

Fix this by skipping the first element. Also replace the pointer
logic with an index variable which is easier to read.

Link: https://lkml.kernel.org/r/20230816154928.4171614-3-svens@linux.ibm.com

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing/synthetic: Use union instead of casts

The current code uses a lot of casts to access the fields member in struct
synth_trace_events with different sizes. This makes the code hard to
read, and had already introduced an endianness bug. Use a union and struct
instead.

Link: https://lkml.kernel.org/r/20230816154928.4171614-2-svens@linux.ibm.com

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 00cf3d672a9dd ("tracing: Allow synthetic events to pass around stacktraces")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing/synthetic: Fix kernel-doc warnings in trace_events_synth.c

Fix kernel-doc warning:

kernel/trace/trace_events_synth.c:1257: warning: Function parameter
or member 'mod' not described in 'synth_event_gen_cmd_array_start'

Link: https://lkml.kernel.org/r/20230724140827.1023266-3-cuigaosheng1@huawei.com

Cc: <mhiramat@kernel.org>
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing/synthetic: Make lastcmd_mutex static

The lastcmd_mutex is only used in trace_events_synth.c and should be
static.

Link: https://lore.kernel.org/linux-trace-kernel/202304062033.cRStgOuP-lkp@intel.com/
Link: https://lore.kernel.org/linux-trace-kernel/20230406111033.6e26de93@gandalf.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Tze-nan Wu <Tze-nan.Wu@mediatek.com>
Fixes: 4ccf11c4e8a8e ("tracing/synthetic: Fix races on freeing last_cmd")
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing/synthetic: Fix races on freeing last_cmd

Currently, the "last_cmd" variable can be accessed by multiple processes
asynchronously when multiple users manipulate synthetic_events node
at the same time, it could lead to use-after-free or double-free.

This patch add "lastcmd_mutex" to prevent "last_cmd" from being accessed
asynchronously.

================================================================

It's easy to reproduce in the KASAN environment by running the two
scripts below in different shells.

script 1:
while :
do
echo -n -e '\x88' > /sys/kernel/tracing/synthetic_events
done

script 2:
while :
do
echo -n -e '\xb0' > /sys/kernel/tracing/synthetic_events
done

================================================================
double-free scenario:

process A process B
------------------- ---------------
1.kstrdup last_cmd
2.free last_cmd
3.free last_cmd(double-free)

================================================================
use-after-free scenario:

process A process B
------------------- ---------------
1.kstrdup last_cmd
2.free last_cmd
3.tracing_log_err(use-after-free)

================================================================

Appendix 1. KASAN report double-free:

BUG: KASAN: double-free in kfree+0xdc/0x1d4
Free of addr ***** by task sh/4879
Call trace:
...
kfree+0xdc/0x1d4
create_or_delete_synth_event+0x60/0x1e8
trace_parse_run_command+0x2bc/0x4b8
synth_events_write+0x20/0x30
vfs_write+0x200/0x830
...

Allocated by task 4879:
...
kstrdup+0x5c/0x98
create_or_delete_synth_event+0x6c/0x1e8
trace_parse_run_command+0x2bc/0x4b8
synth_events_write+0x20/0x30
vfs_write+0x200/0x830
...

Freed by task 5464:
...
kfree+0xdc/0x1d4
create_or_delete_synth_event+0x60/0x1e8
trace_parse_run_command+0x2bc/0x4b8
synth_events_write+0x20/0x30
vfs_write+0x200/0x830
...

================================================================
Appendix 2. KASAN report use-after-free:

BUG: KASAN: use-after-free in strlen+0x5c/0x7c
Read of size 1 at addr ***** by task sh/5483
sh: CPU: 7 PID: 5483 Comm: sh
...
__asan_report_load1_noabort+0x34/0x44
strlen+0x5c/0x7c
tracing_log_err+0x60/0x444
create_or_delete_synth_event+0xc4/0x204
trace_parse_run_command+0x2bc/0x4b8
synth_events_write+0x20/0x30
vfs_write+0x200/0x830
...

Allocated by task 5483:
...
kstrdup+0x5c/0x98
create_or_delete_synth_event+0x80/0x204
trace_parse_run_command+0x2bc/0x4b8
synth_events_write+0x20/0x30
vfs_write+0x200/0x830
...

Freed by task 5480:
...
kfree+0xdc/0x1d4
create_or_delete_synth_event+0x74/0x204
trace_parse_run_command+0x2bc/0x4b8
synth_events_write+0x20/0x30
vfs_write+0x200/0x830
...

Link: https://lore.kernel.org/linux-trace-kernel/20230321110444.1587-1-Tze-nan.Wu@mediatek.com

Fixes: 27c888da9867 ("tracing: Remove size restriction on synthetic event cmd error logging")
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: "Tom Zanussi" <zanussi@kernel.org>
Signed-off-by: Tze-nan Wu <Tze-nan.Wu@mediatek.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

kernel/trace: Provide default impelentations defined in trace_probe_tmpl.h

There are 6 function definitions in trace_probe_tmpl.h, they are:

1, fetch_store_strlen
2, fetch_store_string
3, fetch_store_strlen_user
4, fetch_store_string_user
5, probe_mem_read
6, probe_mem_read_user

Every C file which includes trace_probe_tmpl.h has to implement them,
otherwise it gets warnings and errors. However, some of them are identical,
like kprobe and eprobe, as a result, there is a lot redundant code in those
2 files.

This patch would like to provide default behaviors for those functions
which kprobe and eprobe can share by just including trace_probe_kernel.h
with trace_probe_tmpl.h together.

It removes redundant code, increases readability, and more importantly,
makes it easier to introduce a new feature based on trace probe
(it's possible).

Link: https://lore.kernel.org/all/1672382018-18347-1-git-send-email-chensong_2000@189.cn/

Signed-off-by: Song Chen <chensong_2000@189.cn>
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

tracing/histogram: Don't use strlen to find length of stacktrace variables

Because stacktraces are saved in dynamic strings,
trace_event_raw_event_synth() uses strlen to determine the length of
the stack. Stacktraces may contain 0-bytes, though, in the saved
addresses, so the length found and passed to reserve() will be too
small.

Fix this by using the first unsigned long in the stack variables to
store the actual number of elements in the stack and have
trace_event_raw_event_synth() use that to determine the length of the
stack.

Link: https://lkml.kernel.org/r/1ed6906cd9d6477ef2bd8e63c61de20a9ffe64d7.1676063532.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing: Fix trace_event_raw_event_synth() if else statement

The test to check if the field is a stack is to be done if it is not a
string. But the code had:

} if (event->fields[i]->is_stack) {

and not

} else if (event->fields[i]->is_stack) {

which would cause it to always be tested. Worse yet, this also included an
"else" statement that was only to be called if the field was not a string
and a stack, but this code allows it to be called if it was a string (and
not a stack).

Also fixed some whitespace issues.

Link: https://lore.kernel.org/all/202301302110.mEtNwkBD-lkp@intel.com/
Link: https://lore.kernel.org/linux-trace-kernel/20230131095237.63e3ca8d@gandalf.local.home

Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

tracing: Allow synthetic events to pass around stacktraces

Allow a stacktrace from one event to be displayed by the end event of a
synthetic event. This is very useful when looking for the longest latency
of a sleep or something blocked on I/O.

# cd /sys/kernel/tracing/
# echo 's:block_lat pid_t pid; u64 delta; unsigned long[] stack;' > dynamic_events
# echo 'hist:keys=next_pid:ts=common_timestamp.usecs,st=stacktrace if prev_state == 1||prev_state == 2' > events/sched/sched_switch/trigger
# echo 'hist:keys=prev_pid:delta=common_timestamp.usecs-$ts,s=$st:onmax($delta).trace(block_lat,prev_pid,$delta,$s)' >> events/sched/sched_switch/trigger

The above creates a "block_lat" synthetic event that take the stacktrace of
when a task schedules out in either the interruptible or uninterruptible
states, and on a new per process max $delta (the time it was scheduled
out), will print the process id and the stacktrace.

# echo 1 > events/synthetic/block_lat/enable
# cat trace
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
kworker/u16:0-767 [006] d..4. 560.645045: block_lat: pid=767 delta=66 stack=STACK:
=> __schedule
=> schedule
=> pipe_read
=> vfs_read
=> ksys_read
=> do_syscall_64
=> 0x966000aa

<idle>-0 [003] d..4. 561.132117: block_lat: pid=0 delta=413787 stack=STACK:
=> __schedule
=> schedule
=> schedule_hrtimeout_range_clock
=> do_sys_poll
=> __x64_sys_poll
=> do_syscall_64
=> 0x966000aa

<...>-153 [006] d..4. 562.068407: block_lat: pid=153 delta=54 stack=STACK:
=> __schedule
=> schedule
=> io_schedule
=> rq_qos_wait
=> wbt_wait
=> __rq_qos_throttle
=> blk_mq_submit_bio
=> submit_bio_noacct_nocheck
=> ext4_bio_write_page
=> mpage_submit_page
=> mpage_process_page_bufs
=> mpage_prepare_extent_to_map
=> ext4_do_writepages
=> ext4_writepages
=> do_writepages
=> __writeback_single_inode

Link: https://lkml.kernel.org/r/20230117152236.010941267@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Ross Zwisler <zwisler@google.com>
Cc: Ching-lin Yu <chinglinyu@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing: Simplify calculating entry size using struct_size()

When tracing a dynamic string field for a synthetic event, the offset
calculation for where to write the next event can use struct_size() to
find what the current size of the structure is.

This simplifies the code and makes it less error prone.

Link: https://lkml.kernel.org/r/20230117152235.698632147@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Ross Zwisler <zwisler@google.com>
Cc: Ching-lin Yu <chinglinyu@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing: Fix issue of missing one synthetic field

The maximum number of synthetic fields supported is defined as
SYNTH_FIELDS_MAX which value currently is 64, but it actually fails
when try to generate a synthetic event with 64 fields by executing like:

# echo "my_synth_event int v1; int v2; int v3; int v4; int v5; int v6;\
int v7; int v8; int v9; int v10; int v11; int v12; int v13; int v14;\
int v15; int v16; int v17; int v18; int v19; int v20; int v21; int v22;\
int v23; int v24; int v25; int v26; int v27; int v28; int v29; int v30;\
int v31; int v32; int v33; int v34; int v35; int v36; int v37; int v38;\
int v39; int v40; int v41; int v42; int v43; int v44; int v45; int v46;\
int v47; int v48; int v49; int v50; int v51; int v52; int v53; int v54;\
int v55; int v56; int v57; int v58; int v59; int v60; int v61; int v62;\
int v63; int v64" >> /sys/kernel/tracing/synthetic_events

Correct the field counting to fix it.

Link: https://lore.kernel.org/linux-trace-kernel/20221207091557.3137904-1-zhengyejian1@huawei.com

Cc: <mhiramat@kernel.org>
Cc: <zanussi@kernel.org>
Cc: stable@vger.kernel.org
Fixes: c9e759b1e845 ("tracing: Rework synthetic event command parsing")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing: Add tracing_reset_all_online_cpus_unlocked() function

Currently the tracing_reset_all_online_cpus() requires the
trace_types_lock held. But only one caller of this function actually has
that lock held before calling it, and the other just takes the lock so
that it can call it. More users of this function is needed where the lock
is not held.

Add a tracing_reset_all_online_cpus_unlocked() function for the one use
case that calls it without being held, and also add a lockdep_assert to
make sure it is held when called.

Then have tracing_reset_all_online_cpus() take the lock internally, such
that callers do not need to worry about taking it.

Link: https://lkml.kernel.org/r/20221123192741.658273220@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing: Fix wild-memory-access in register_synth_event()

In register_synth_event(), if set_synth_event_print_fmt() failed, then
both trace_remove_event_call() and unregister_trace_event() will be
called, which means the trace_event_call will call
__unregister_trace_event() twice. As the result, the second unregister
will causes the wild-memory-access.

register_synth_event
set_synth_event_print_fmt failed
trace_remove_event_call
event_remove
if call->event.funcs then
__unregister_trace_event (first call)
unregister_trace_event
__unregister_trace_event (second call)

Fix the bug by avoiding to call the second __unregister_trace_event() by
checking if the first one is called.

general protection fault, probably for non-canonical address
0xfbd59c0000000024: 0000 [#1] SMP KASAN PTI
KASAN: maybe wild-memory-access in range
[0xdead000000000120-0xdead000000000127]
CPU: 0 PID: 3807 Comm: modprobe Not tainted
6.1.0-rc1-00186-g76f33a7eedb4 #299
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
RIP: 0010:unregister_trace_event+0x6e/0x280
Code: 00 fc ff df 4c 89 ea 48 c1 ea 03 80 3c 02 00 0f 85 0e 02 00 00 48
b8 00 00 00 00 00 fc ff df 4c 8b 63 08 4c 89 e2 48 c1 ea 03 <80> 3c 02
00 0f 85 e2 01 00 00 49 89 2c 24 48 85 ed 74 28 e8 7a 9b
RSP: 0018:ffff88810413f370 EFLAGS: 00010a06
RAX: dffffc0000000000 RBX: ffff888105d050b0 RCX: 0000000000000000
RDX: 1bd5a00000000024 RSI: ffff888119e276e0 RDI: ffffffff835a8b20
RBP: dead000000000100 R08: 0000000000000000 R09: fffffbfff0913481
R10: ffffffff8489a407 R11: fffffbfff0913480 R12: dead000000000122
R13: ffff888105d050b8 R14: 0000000000000000 R15: ffff888105d05028
FS: 00007f7823e8d540(0000) GS:ffff888119e00000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7823e7ebec CR3: 000000010a058002 CR4: 0000000000330ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__create_synth_event+0x1e37/0x1eb0
create_or_delete_synth_event+0x110/0x250
synth_event_run_command+0x2f/0x110
test_gen_synth_cmd+0x170/0x2eb [synth_event_gen_test]
synth_event_gen_test_init+0x76/0x9bc [synth_event_gen_test]
do_one_initcall+0xdb/0x480
do_init_module+0x1cf/0x680
load_module+0x6a50/0x70a0
__do_sys_finit_module+0x12f/0x1c0
do_syscall_64+0x3f/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Link: https://lkml.kernel.org/r/20221117012346.22647-3-shangxiaojing@huawei.com

Fixes: 4b147936fa50 ("tracing: Add support for 'synthetic' events")
Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
Cc: stable@vger.kernel.org
Cc: <mhiramat@kernel.org>
Cc: <zanussi@kernel.org>
Cc: <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing: Fix reading strings from synthetic events

The follow commands caused a crash:

# cd /sys/kernel/tracing
# echo 's:open char file[]' > dynamic_events
# echo 'hist:keys=common_pid:file=filename:onchange($file).trace(open,$file)' > events/syscalls/sys_enter_openat/trigger'
# echo 1 > events/synthetic/open/enable

BOOM!

The problem is that the synthetic event field "char file[]" will read
the value given to it as a string without any memory checks to make sure
the address is valid. The above example will pass in the user space
address and the sythetic event code will happily call strlen() on it
and then strscpy() where either one will cause an oops when accessing
user space addresses.

Use the helper functions from trace_kprobe and trace_eprobe that can
read strings safely (and actually succeed when the address is from user
space and the memory is mapped in).

Now the above can show:

packagekitd-1721 [000] ...2. 104.597170: open: file=/usr/lib/rpm/fileattrs/cmake.attr
in:imjournal-978 [006] ...2. 104.599642: open: file=/var/lib/rsyslog/imjournal.state.tmp
packagekitd-1721 [000] ...2. 104.626308: open: file=/usr/lib/rpm/fileattrs/debuginfo.attr

Link: https://lkml.kernel.org/r/20221012104534.826549315@goodmis.org

Cc: stable@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Fixes: bd82631d7ccdc ("tracing: Add support for dynamic strings to synthetic events")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing: Fix strncpy warning in trace_events_synth.c

0-day reported the strncpy error below:

../kernel/trace/trace_events_synth.c: In function 'last_cmd_set':
../kernel/trace/trace_events_synth.c:65:9: warning: 'strncpy' specified bound depends on the length o\
f the source argument [-Wstringop-truncation]
65 | strncpy(last_cmd, str, strlen(str) + 1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../kernel/trace/trace_events_synth.c:65:32: note: length computed here
65 | strncpy(last_cmd, str, strlen(str) + 1);
| ^~~~~~~~~~~

There's no reason to use strncpy here, in fact there's no reason to do
anything but a simple kstrdup() (note we don't even need to check for
failure since last_cmod is expected to be either the last cmd string
or NULL, and the containing function is a void return).

Link: https://lkml.kernel.org/r/77deca8cbfd226981b3f1eab203967381e9b5bd9.camel@kernel.org

Fixes: 27c888da9867 ("tracing: Remove size restriction on synthetic event cmd error logging")

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing: Remove size restriction on synthetic event cmd error logging

Currently, synthetic event command error strings are restricted to a
length of MAX_FILTER_STR_VAL (256), which is too short for some
commands already seen in the wild (with cmd strings longer than that
showing up truncated in err_log).

Remove the restriction so that no synthetic event command error string
is ever truncated.

Link: https://lkml.kernel.org/r/0376692396a81d0b795127c66ea92ca5bf60f481.1643399022.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tracing: Do not let synth_events block other dyn_event systems during create

synth_events is returning -EINVAL if the dyn_event create command does
not contain ' \t'. This prevents other systems from getting called back.
synth_events needs to return -ECANCELED in these cases when the command
is not targeting the synth_event system.

Link: https://lore.kernel.org/linux-trace-devel/20210930223821.11025-1-beaub@linux.microsoft.com

Fixes: c9e759b1e8456 ("tracing: Rework synthetic event command parsing")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Fix synth_event_add_val() kernel-doc comment

It's named field here.

Link: https://lkml.kernel.org/r/20210516022410.64271-1-hqjagain@gmail.com

Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Fix possible memory leak in __create_synth_event() error path

There's error paths in __create_synth_event() after the argv is allocated
that fail to free it. Add a jump to free it when necessary.

Link: https://lkml.kernel.org/r/20211209024317.11783-1-linmq006@gmail.com

Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
[ Fixed up the patch and change log ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Disable "other" permission bits in the tracefs files

When building the files in the tracefs file system, do not by default set
any permissions for OTH (other). This will make it easier for admins who
want to define a group for accessing tracefs and not having to first
disable all the permission bits for "other" in the file system.

As tracing can leak sensitive information, it should never by default
allowing all users access. An admin can still set the permission bits for
others to have access, which may be useful for creating a honeypot and
seeing who takes advantage of it and roots the machine.

Link: https://lkml.kernel.org/r/20210818153038.864149276@goodmis.org

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Have dynamic events have a ref counter

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 <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Add DYNAMIC flag for dynamic events

To differentiate between static and dynamic events, add a new flag
DYNAMIC to the event flags that all dynamic events have set. This will
allow to differentiate when attaching to a dynamic event from a static
event.

Static events have a mod pointer that references the module they were
created in (or NULL for core kernel). This can be incremented when the
event has something attached to it. But there exists no such mechanism for
dynamic events. This is dangerous as the dynamic events may now disappear
without the "attachment" knowing that it no longer exists.

To enforce the dynamic flag, change dyn_event_add() to pass the event that
is being created such that it can set the DYNAMIC flag of the event. This
helps make sure that no location that creates a dynamic event misses
setting this flag.

Link: https://lore.kernel.org/linux-trace-devel/20210813004448.51c7de69ce432d338f4d226b@kernel.org/
Link: https://lkml.kernel.org/r/20210817035026.936958254@goodmis.org

Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Clean up alloc_synth_event()

alloc_synth_event() currently has the following code to initialize the
event fields and dynamic_fields:

for (i = 0, j = 0; i < n_fields; i++) {
event->fields[i] = fields[i];

if (fields[i]->is_dynamic) {
event->dynamic_fields[j] = fields[i];
event->dynamic_fields[j]->field_pos = i;
event->dynamic_fields[j++] = fields[i];
event->n_dynamic_fields++;
}
}

1) It would make more sense to have all fields keep track of their
field_pos.

2) event->dynmaic_fields[j] is assigned twice for no reason.

3) We can move updating event->n_dynamic_fields outside the loop, and just
assign it to j.

This combination makes the code much cleaner.

Link: https://lkml.kernel.org/r/20210721195341.29bb0f77@oasis.local.home

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Fix various typos in comments

Fix ~59 single-word typos in the tracing code comments, and fix
the grammar in a handful of places.

Link: https://lore.kernel.org/r/20210322224546.GA1981273@gmail.com
Link: https://lkml.kernel.org/r/20210323174935.GA4176821@gmail.com

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Fix memory leak in __create_synth_event()

kmemleak report:
unreferenced object 0xc5a6f708 (size 8):
comm "ftracetest", pid 1209, jiffies 4294911500 (age 6.816s)
hex dump (first 8 bytes):
00 c1 3d 60 14 83 1f 8a ..=`....
backtrace:
[<f0aa4ac4>] __kmalloc_track_caller+0x2a6/0x460
[<7d3d60a6>] kstrndup+0x37/0x70
[<45a0e739>] argv_split+0x1c/0x120
[<c17982f8>] __create_synth_event+0x192/0xb00
[<0708b8a3>] create_synth_event+0xbb/0x150
[<3d1941e1>] create_dyn_event+0x5c/0xb0
[<5cf8b9e3>] trace_parse_run_command+0xa7/0x140
[<04deb2ef>] dyn_event_write+0x10/0x20
[<8779ac95>] vfs_write+0xa9/0x3c0
[<ed93722a>] ksys_write+0x89/0xc0
[<b9ca0507>] __ia32_sys_write+0x15/0x20
[<7ce02d85>] __do_fast_syscall_32+0x45/0x80
[<cb0ecb35>] do_fast_syscall_32+0x29/0x60
[<2467454a>] do_SYSENTER_32+0x15/0x20
[<9beaa61d>] entry_SYSENTER_32+0xa9/0xfc
unreferenced object 0xc5a6f078 (size 8):
comm "ftracetest", pid 1209, jiffies 4294911500 (age 6.816s)
hex dump (first 8 bytes):
08 f7 a6 c5 00 00 00 00 ........
backtrace:
[<bbac096a>] __kmalloc+0x2b6/0x470
[<aa2624b4>] argv_split+0x82/0x120
[<c17982f8>] __create_synth_event+0x192/0xb00
[<0708b8a3>] create_synth_event+0xbb/0x150
[<3d1941e1>] create_dyn_event+0x5c/0xb0
[<5cf8b9e3>] trace_parse_run_command+0xa7/0x140
[<04deb2ef>] dyn_event_write+0x10/0x20
[<8779ac95>] vfs_write+0xa9/0x3c0
[<ed93722a>] ksys_write+0x89/0xc0
[<b9ca0507>] __ia32_sys_write+0x15/0x20
[<7ce02d85>] __do_fast_syscall_32+0x45/0x80
[<cb0ecb35>] do_fast_syscall_32+0x29/0x60
[<2467454a>] do_SYSENTER_32+0x15/0x20
[<9beaa61d>] entry_SYSENTER_32+0xa9/0xfc

In __create_synth_event(), while iterating field/type arguments, the
argv_split() will return array of atleast 2 elements even when zero
arguments(argc=0) are passed. for e.g. when there is double delimiter
or string ends with delimiter

To fix call argv_free() even when argc=0.

Link: https://lkml.kernel.org/r/20210304094521.GA1826@cosmos

Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Add a backward-compatibility check for synthetic event creation

The synthetic event parsing rework now requires semicolons between
synthetic event fields. That requirement breaks existing users who
might already have used the old synthetic event command format, so
this adds an inner loop that can parse more than one field, if
present, between semicolons. For each field, parse_synth_field()
checks in which version that field was introduced, using
check_field_version(). The caller, __create_synth_event() can then use
that version information to determine whether or not to enforce the
requirement on the command as a whole.

In the future, if/when new features are added, the requirement will be
that any field/string containing the new feature must use semicolons,
and the check_field_version() check can then check for those and
enforce it. Using a version number allows this scheme to be extended
if necessary.

Link: https://lkml.kernel.org/r/74fcc500d561b40ce91c5ee94818c70c6b0c9330.1612208610.git.zanussi@kernel.org

[ zanussi: added check_field_version() comment from rostedt@goodmis.org ]
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Update synth command errors

Since array types are handled differently, errors referencing them
also need to be handled differently. Add and use a new
INVALID_ARRAY_SPEC error. Also add INVALID_CMD and INVALID_DYN_CMD to
catch and display the correct form for badly-formed commands, which
can also be used in place of CMD_INCOMPLETE, which is removed, and
remove CMD_TOO_LONG, since it's no longer used.

Link: https://lkml.kernel.org/r/b9dd434dc6458dcff11adc6ed616fe93a8794770.1612208610.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Rework synthetic event command parsing

Now that command parsing has been delegated to the create functions
and we're no longer constrained by argv_split(), we can modify the
synthetic event command parser to better match the higher-level
structure of the synthetic event commands, which is basically an event
name followed by a set of semicolon-separated fields.

Since we're also now passed the raw command, we can also save it
directly and can get rid of save_cmdstr().

Link: https://lkml.kernel.org/r/cb9e2be92d992ce59f2b4f132264a5d467f3933f.1612208610.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing/dynevent: Delegate parsing to create function

Delegate command parsing to each create function so that the
command syntax can be customized.

This requires changes to the kprobe/uprobe/synthetic event handling,
which are also included here.

Link: https://lkml.kernel.org/r/e488726f49cbdbc01568618f8680584306c4c79f.1612208610.git.zanussi@kernel.org

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
[ zanussi@kernel.org: added synthetic event modifications ]
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Fix some typos in comments

s/detetector/detector/
s/enfoced/enforced/
s/writen/written/
s/actualy/actually/
s/bascially/basically/
s/Regarldess/Regardless/
s/zeroes/zeros/
s/followd/followed/
s/incrememented/incremented/
s/separatelly/separately/
s/accesible/accessible/
s/sythetic/synthetic/
s/enabed/enabled/
s/heurisitc/heuristic/
s/assocated/associated/
s/otherwides/otherwise/
s/specfied/specified/
s/seaching/searching/
s/hierachry/hierarchy/
s/internel/internal/
s/Thise/This/

Link: https://lkml.kernel.org/r/20201029150554.3354-1-hqjagain@gmail.com

Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Make -ENOMEM the default error for parse_synth_field()

parse_synth_field() returns a pointer and requires that errors get
surrounded by ERR_PTR(). The ret variable is initialized to zero, but should
never be used as zero, and if it is, it could cause a false return code and
produce a NULL pointer dereference. It makes no sense to set ret to zero.

Set ret to -ENOMEM (the most common error case), and have any other errors
set it to something else. This removes the need to initialize ret on *every*
error branch.

Fixes: 761a8c58db6b ("tracing, synthetic events: Replace buggy strcat() with seq_buf operations")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing, synthetic events: Replace buggy strcat() with seq_buf operations

There was a memory corruption bug happening while running the synthetic
event selftests:

kmemleak: Cannot insert 0xffff8c196fa2afe5 into the object search tree (overlaps existing)
CPU: 5 PID: 6866 Comm: ftracetest Tainted: G W 5.9.0-rc5-test+ #577
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016
Call Trace:
dump_stack+0x8d/0xc0
create_object.cold+0x3b/0x60
slab_post_alloc_hook+0x57/0x510
? tracing_map_init+0x178/0x340
__kmalloc+0x1b1/0x390
tracing_map_init+0x178/0x340
event_hist_trigger_func+0x523/0xa40
trigger_process_regex+0xc5/0x110
event_trigger_write+0x71/0xd0
vfs_write+0xca/0x210
ksys_write+0x70/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fef0a63a487
Code: 64 89 02 48 c7 c0 ff ff ff ff eb bb 0f 1f 80 00 00 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
RSP: 002b:00007fff76f18398 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000039 RCX: 00007fef0a63a487
RDX: 0000000000000039 RSI: 000055eb3b26d690 RDI: 0000000000000001
RBP: 000055eb3b26d690 R08: 000000000000000a R09: 0000000000000038
R10: 000055eb3b2cdb80 R11: 0000000000000246 R12: 0000000000000039
R13: 00007fef0a70b500 R14: 0000000000000039 R15: 00007fef0a70b700
kmemleak: Kernel memory leak detector disabled
kmemleak: Object 0xffff8c196fa2afe0 (size 8):
kmemleak: comm "ftracetest", pid 6866, jiffies 4295082531
kmemleak: min_count = 1
kmemleak: count = 0
kmemleak: flags = 0x1
kmemleak: checksum = 0
kmemleak: backtrace:
__kmalloc+0x1b1/0x390
tracing_map_init+0x1be/0x340
event_hist_trigger_func+0x523/0xa40
trigger_process_regex+0xc5/0x110
event_trigger_write+0x71/0xd0
vfs_write+0xca/0x210
ksys_write+0x70/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9

The cause came down to a use of strcat() that was adding an string that was
shorten, but the strcat() did not take that into account.

strcat() is extremely dangerous as it does not care how big the buffer is.
Replace it with seq_buf operations that prevent the buffer from being
overwritten if what is being written is bigger than the buffer.

Fixes: 10819e25799a ("tracing: Handle synthetic event array field type checking correctly")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Tested-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: support "bool" type in synthetic trace events

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 <walken@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Handle synthetic event array field type checking correctly

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

[ <rostedt@goodmis.org>: wrote parse_synth_field() snippet. ]
Fixes: 4b147936fa50 (tracing: Add support for 'synthetic' events)
Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Add synthetic event error logging

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

[ <rostedt@goodmis.org>: wrote save_cmdstr() seq_buf implementation. ]
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

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

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 <mhiramat@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

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

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 <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

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

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 <colin.king@canonical.com>
Acked-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Change synthetic event string format to limit printed length

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) <rostedt@goodmis.org>

tracing: Add support for dynamic strings to synthetic events

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.

[ <rostedt@goodmis.org>: 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 <axelrasmussen@google.com>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Fix parse_synth_field() error handling

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 <mhiramat@kernel.org>
Tested-by: Axel Rasmussen <axelrasmussen@google.com>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

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

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 <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Delete repeated words in comments

Drop repeated words in kernel/trace/.
{and, the, not}

Link: https://lkml.kernel.org/r/20200807033259.13778-1-rdunlap@infradead.org

Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer

Current tracing_init_dentry() return a d_entry pointer, while is not
necessary. This function returns NULL on success or error on failure,
which means there is no valid d_entry pointer return.

Let's return 0 on success and negative value for error.

Link: https://lkml.kernel.org/r/20200712011036.70948-5-richard.weiyang@linux.alibaba.com

Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: Move synthetic events to a separate file

With the addition of the in-kernel synthetic event API, synthetic
events are no longer specifically tied to the histogram triggers.

The synthetic event code is also making trace_event_hist.c very
bloated, so for those reasons, move it to a separate file,
trace_events_synth.c, along with a new trace_synth.h header file.

Because synthetic events are now independent from hist triggers, add a
new CONFIG_SYNTH_EVENTS config option, and have CONFIG_HIST_TRIGGERS
select it, and have CONFIG_SYNTH_EVENT_GEN_TEST depend on it.

Link: http://lkml.kernel.org/r/4d1fa1f85ed5982706ac44844ac92451dcb04715.1590693308.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>