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Fix a typo ("Invalid $-variable") in a log message.
Link: https://lore.kernel.org/all/20260507081041.885781-4-martin@kaiser.cx/
Fixes: ab105a4fb894 ("tracing: Use tracing error_log with probe events")
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Add syntax to the parsing of eprobes to be able to typecast a trace event
field that is a pointer to a structure.
Currently, a dereference must be a number, where the user has to figure
out manually the offset of a member of a structure that they want to
dereference.
But for event probes that records a field that happens to be a pointer to
a structure, it cannot dereference these values with BTF naming, but
must use numerical offsets.
For example, to find out what device a sk_buff is pointing to in the
net_dev_xmit trace event, one must first use gdb to find the offsets of the
members of the structures:
(gdb) p &((struct sk_buff *)0)->dev
$1 = (struct net_device **) 0x10
(gdb) p &((struct net_device *)0)->name
$2 = (char (*)[16]) 0x118
And then use the raw numbers to dereference:
# echo 'e:xmit net.net_dev_xmit +0x118(+0x10($skbaddr)):string' >> dynamic_events
If BTF is in the kernel, then instead, the skbaddr can be typecast to
sk_buff and use the normal dereference logic.
# echo 'e:xmit net.net_dev_xmit (sk_buff)skbaddr->dev->name:string' >> dynamic_events
# echo 1 > events/eprobes/xmit/enable
# cat trace
[..]
sshd-session-1022 [000] b..2. 860.249343: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.250061: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.250142: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.263553: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.283820: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.302716: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.322905: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.342828: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.362268: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.382335: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.400856: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.419893: xmit: (net.net_dev_xmit) arg1="enp7s0"
The syntax is simply: (STRUCT)(FIELD)->MEMBER[->MEMBER..]
Also add comments around the #else and #endif of #ifdef CONFIG_PROBE_EVENTS_BTF_ARGS
to know what they are for.
Link: https://lore.kernel.org/all/20260601130746.2139d926@gandalf.local.home/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Store probe entry fetch instructions in the probe_entry_arg
allocation instead of allocating a separate instruction array.
This keeps the entry fetch code tied to the entry argument lifetime while
leaving regular probe_arg instruction arrays separately allocated and
freed.
Assisted-by: Codex:GPT-5.5
Link: https://lore.kernel.org/all/20260520215817.16560-1-rosenp@gmail.com/
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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There currently isn't a max limit an event probe can be. One could make an
event greater than PAGE_SIZE, which makes the event useless because if
it's bigger than the max event that can be recorded into the ring buffer,
then it will never be recorded.
A event probe should never need to be greater than 3K, so make that the
max size. As long as the max is less than the max that can be recorded
onto the ring buffer, it should be fine.
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes: 93ccae7a22274 ("tracing/kprobes: Support basic types on dynamic events")
Link: https://patch.msgid.link/20260428122302.706610ba@gandalf.local.home
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Use __free() for trace_probe_log_clear() to cleanup error log interface.
Link: https://lore.kernel.org/all/175509538609.193596.16646724647358218778.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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dereference
There is a critical race condition in kprobe initialization that can lead to
NULL pointer dereference and kernel crash.
[1135630.084782] Unable to handle kernel paging request at virtual address 0000710a04630000
...
[1135630.260314] pstate: 404003c9 (nZcv DAIF +PAN -UAO)
[1135630.269239] pc : kprobe_perf_func+0x30/0x260
[1135630.277643] lr : kprobe_dispatcher+0x44/0x60
[1135630.286041] sp : ffffaeff4977fa40
[1135630.293441] x29: ffffaeff4977fa40 x28: ffffaf015340e400
[1135630.302837] x27: 0000000000000000 x26: 0000000000000000
[1135630.312257] x25: ffffaf029ed108a8 x24: ffffaf015340e528
[1135630.321705] x23: ffffaeff4977fc50 x22: ffffaeff4977fc50
[1135630.331154] x21: 0000000000000000 x20: ffffaeff4977fc50
[1135630.340586] x19: ffffaf015340e400 x18: 0000000000000000
[1135630.349985] x17: 0000000000000000 x16: 0000000000000000
[1135630.359285] x15: 0000000000000000 x14: 0000000000000000
[1135630.368445] x13: 0000000000000000 x12: 0000000000000000
[1135630.377473] x11: 0000000000000000 x10: 0000000000000000
[1135630.386411] x9 : 0000000000000000 x8 : 0000000000000000
[1135630.395252] x7 : 0000000000000000 x6 : 0000000000000000
[1135630.403963] x5 : 0000000000000000 x4 : 0000000000000000
[1135630.412545] x3 : 0000710a04630000 x2 : 0000000000000006
[1135630.421021] x1 : ffffaeff4977fc50 x0 : 0000710a04630000
[1135630.429410] Call trace:
[1135630.434828] kprobe_perf_func+0x30/0x260
[1135630.441661] kprobe_dispatcher+0x44/0x60
[1135630.448396] aggr_pre_handler+0x70/0xc8
[1135630.454959] kprobe_breakpoint_handler+0x140/0x1e0
[1135630.462435] brk_handler+0xbc/0xd8
[1135630.468437] do_debug_exception+0x84/0x138
[1135630.475074] el1_dbg+0x18/0x8c
[1135630.480582] security_file_permission+0x0/0xd0
[1135630.487426] vfs_write+0x70/0x1c0
[1135630.493059] ksys_write+0x5c/0xc8
[1135630.498638] __arm64_sys_write+0x24/0x30
[1135630.504821] el0_svc_common+0x78/0x130
[1135630.510838] el0_svc_handler+0x38/0x78
[1135630.516834] el0_svc+0x8/0x1b0
kernel/trace/trace_kprobe.c: 1308
0xffff3df8995039ec <kprobe_perf_func+0x2c>: ldr x21, [x24,#120]
include/linux/compiler.h: 294
0xffff3df8995039f0 <kprobe_perf_func+0x30>: ldr x1, [x21,x0]
kernel/trace/trace_kprobe.c
1308: head = this_cpu_ptr(call->perf_events);
1309: if (hlist_empty(head))
1310: return 0;
crash> struct trace_event_call -o
struct trace_event_call {
...
[120] struct hlist_head *perf_events; //(call->perf_event)
...
}
crash> struct trace_event_call ffffaf015340e528
struct trace_event_call {
...
perf_events = 0xffff0ad5fa89f088, //this value is correct, but x21 = 0
...
}
Race Condition Analysis:
The race occurs between kprobe activation and perf_events initialization:
CPU0 CPU1
==== ====
perf_kprobe_init
perf_trace_event_init
tp_event->perf_events = list;(1)
tp_event->class->reg (2)← KPROBE ACTIVE
Debug exception triggers
...
kprobe_dispatcher
kprobe_perf_func (tk->tp.flags & TP_FLAG_PROFILE)
head = this_cpu_ptr(call->perf_events)(3)
(perf_events is still NULL)
Problem:
1. CPU0 executes (1) assigning tp_event->perf_events = list
2. CPU0 executes (2) enabling kprobe functionality via class->reg()
3. CPU1 triggers and reaches kprobe_dispatcher
4. CPU1 checks TP_FLAG_PROFILE - condition passes (step 2 completed)
5. CPU1 calls kprobe_perf_func() and crashes at (3) because
call->perf_events is still NULL
CPU1 sees that kprobe functionality is enabled but does not see that
perf_events has been assigned.
Add pairing read and write memory barriers to guarantee that if CPU1
sees that kprobe functionality is enabled, it must also see that
perf_events has been assigned.
Link: https://lore.kernel.org/all/20251001022025.44626-1-chenyuan_fl@163.com/
Fixes: 50d780560785 ("tracing/kprobes: Add probe handler dispatcher to support perf and ftrace concurrent use")
Cc: stable@vger.kernel.org
Signed-off-by: Yuan Chen <chenyuan@kylinos.cn>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Instead of allocating traceprobe_parse_context on stack, allocate it
dynamically from heap (slab).
This change is likely intended to prevent potential stack overflow
issues, which can be a concern in the kernel environment where stack
space is limited.
Link: https://lore.kernel.org/all/175323425650.57270.280750740753792504.stgit@devnote2/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202506240416.nZIhDXoO-lkp@intel.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Sort the #include directives in trace_probe* files alphabetically for
easier maintenance and avoid double includes.
This also groups headers as linux-generic, asm-generic, and local
headers.
Link: https://lore.kernel.org/all/175323424678.57270.11975372127870059007.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Add error message when the number of arguments exceeds the limitation.
Link: https://lore.kernel.org/all/174055075075.4079315.10916648136898316476.stgit@mhiramat.tok.corp.google.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Commit 18b1e870a496 ("tracing/probes: Add $arg* meta argument for all
function args") introduced MAX_ARG_BUF_LEN but it is not used.
Remove it.
Link: https://lore.kernel.org/all/174055075876.4079315.8805416872155957588.stgit@mhiramat.tok.corp.google.com/
Fixes: 18b1e870a496 ("tracing/probes: Add $arg* meta argument for all function args")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Add error message when the number of entry argument exceeds the
maximum size of entry data.
This is currently checked when registering fprobe, but in this case
no error message is shown in the error_log file.
Link: https://lore.kernel.org/all/174055074269.4079315.17809232650360988538.stgit@mhiramat.tok.corp.google.com/
Fixes: 25f00e40ce79 ("tracing/probes: Support $argN in return probe (kprobe and fprobe)")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Commit 57a7e6de9e30 ("tracing/fprobe: Support raw tracepoints on
future loaded modules") allows user to set a tprobe on non-exist
tracepoint but it does not check the tracepoint name is acceptable.
So it leads tprobe has a wrong character for events (e.g. with
subsystem prefix). In this case, the event is not shown in the
events directory.
Reject such invalid tracepoint name.
The tracepoint name must consist of alphabet or digit or '_'.
Link: https://lore.kernel.org/all/174055073461.4079315.15875502830565214255.stgit@mhiramat.tok.corp.google.com/
Fixes: 57a7e6de9e30 ("tracing/fprobe: Support raw tracepoints on future loaded modules")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: stable@vger.kernel.org
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During fault locating, the file name needs to be printed based on the
dentry address. The offset needs to be calculated each time, which
is troublesome. Similar to printk, kprobe support print type '%pd' for
print dentry's name. For example "name=$arg1:%pd" casts the `$arg1`
as (struct dentry *), dereferences the "d_name.name" field and stores
it to "name" argument as a kernel string.
Here is an example:
[tracing]# echo 'p:testprobe dput name=$arg1:%pd' > kprobe_events
[tracing]# echo 1 > events/kprobes/testprobe/enable
[tracing]# grep -q "1" events/kprobes/testprobe/enable
[tracing]# echo 0 > events/kprobes/testprobe/enable
[tracing]# cat trace | grep "enable"
bash-14844 [002] ..... 16912.889543: testprobe: (dput+0x4/0x30) name="enable"
grep-15389 [003] ..... 16922.834182: testprobe: (dput+0x4/0x30) name="enable"
grep-15389 [003] ..... 16922.836103: testprobe: (dput+0x4/0x30) name="enable"
bash-14844 [001] ..... 16931.820909: testprobe: (dput+0x4/0x30) name="enable"
Note that this expects the given argument (e.g. $arg1) is an address of struct
dentry. User must ensure it.
Link: https://lore.kernel.org/all/20240322064308.284457-2-yebin10@huawei.com/
Signed-off-by: Ye Bin <yebin10@huawei.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Support accessing $argN in the return probe events. This will help users to
record entry data in function return (exit) event for simplfing the function
entry/exit information in one event, and record the result values (e.g.
allocated object/initialized object) at function exit.
For example, if we have a function `int init_foo(struct foo *obj, int param)`
sometimes we want to check how `obj` is initialized. In such case, we can
define a new return event like below;
# echo 'r init_foo retval=$retval param=$arg2 field1=+0($arg1)' >> kprobe_events
Thus it records the function parameter `param` and its result `obj->field1`
(the dereference will be done in the function exit timing) value at once.
This also support fprobe, BTF args and'$arg*'. So if CONFIG_DEBUG_INFO_BTF
is enabled, we can trace both function parameters and the return value
by following command.
# echo 'f target_function%return $arg* $retval' >> dynamic_events
Link: https://lore.kernel.org/all/170952365552.229804.224112990211602895.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Instead of incrementing the trace_probe::nr_args, init it at
trace_probe_init(). Without this change, there is no way to get the number
of trace_probe arguments while parsing it.
This is a cleanup, so the behavior is not changed.
Link: https://lore.kernel.org/all/170952363585.229804.13060759900346411951.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Fix to show a parse error for bad type (non-string) for $comm/$COMM and
immediate-string. With this fix, error_log file shows appropriate error
message as below.
/sys/kernel/tracing # echo 'p vfs_read $comm:u32' >> kprobe_events
sh: write error: Invalid argument
/sys/kernel/tracing # echo 'p vfs_read \"hoge":u32' >> kprobe_events
sh: write error: Invalid argument
/sys/kernel/tracing # cat error_log
[ 30.144183] trace_kprobe: error: $comm and immediate-string only accepts string type
Command: p vfs_read $comm:u32
^
[ 62.618500] trace_kprobe: error: $comm and immediate-string only accepts string type
Command: p vfs_read \"hoge":u32
^
Link: https://lore.kernel.org/all/170602215411.215583.2238016352271091852.stgit@devnote2/
Fixes: 3dd1f7f24f8c ("tracing: probeevent: Fix to make the type of $comm string")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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When a kprobe is attached to a function that's name is not unique (is
static and shares the name with other functions in the kernel), the
kprobe is attached to the first function it finds. This is a bug as the
function that it is attaching to is not necessarily the one that the
user wants to attach to.
Instead of blindly picking a function to attach to what is ambiguous,
error with EADDRNOTAVAIL to let the user know that this function is not
unique, and that the user must use another unique function with an
address offset to get to the function they want to attach to.
Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft.com/
Cc: stable@vger.kernel.org
Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kernel.org/
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull probes updates from Masami Hiramatsu:
- kprobes: use struct_size() for variable size kretprobe_instance data
structure.
- eprobe: Simplify trace_eprobe list iteration.
- probe events: Data structure field access support on BTF argument.
- Update BTF argument support on the functions in the kernel
loadable modules (only loaded modules are supported).
- Move generic BTF access function (search function prototype and
get function parameters) to a separated file.
- Add a function to search a member of data structure in BTF.
- Support accessing BTF data structure member from probe args by
C-like arrow('->') and dot('.') operators. e.g.
't sched_switch next=next->pid vruntime=next->se.vruntime'
- Support accessing BTF data structure member from $retval. e.g.
'f getname_flags%return +0($retval->name):string'
- Add string type checking if BTF type info is available. This will
reject if user specify ":string" type for non "char pointer"
type.
- Automatically assume the fprobe event as a function return event
if $retval is used.
- selftests/ftrace: Add BTF data field access test cases.
- Documentation: Update fprobe event example with BTF data field.
* tag 'probes-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
Documentation: tracing: Update fprobe event example with BTF field
selftests/ftrace: Add BTF fields access testcases
tracing/fprobe-event: Assume fprobe is a return event by $retval
tracing/probes: Add string type check with BTF
tracing/probes: Support BTF field access from $retval
tracing/probes: Support BTF based data structure field access
tracing/probes: Add a function to search a member of a struct/union
tracing/probes: Move finding func-proto API and getting func-param API to trace_btf
tracing/probes: Support BTF argument on module functions
tracing/eprobe: Iterate trace_eprobe directly
kernel: kprobes: Use struct_size()
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Add a string type checking with BTF information if possible.
This will check whether the given BTF argument (and field) is
signed char array or pointer to signed char. If not, it reject
the 'string' type. If it is pointer to signed char, it adds
a dereference opration so that it can correctly fetch the
string data from memory.
# echo 'f getname_flags%return retval->name:string' >> dynamic_events
# echo 't sched_switch next->comm:string' >> dynamic_events
The above cases, 'struct filename::name' is 'char *' and
'struct task_struct::comm' is 'char []'. But in both case,
user can specify ':string' to fetch the string data.
Link: https://lore.kernel.org/all/169272159250.160970.1881112937198526188.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Support BTF argument on '$retval' for function return events including
kretprobe and fprobe for accessing the return value.
This also allows user to access its fields if the return value is a
pointer of a data structure.
E.g.
# echo 'f getname_flags%return +0($retval->name):string' \
> dynamic_events
# echo 1 > events/fprobes/getname_flags__exit/enable
# ls > /dev/null
# head -n 40 trace | tail
ls-87 [000] ...1. 8067.616101: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./function_profile_enabled"
ls-87 [000] ...1. 8067.616108: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./trace_stat"
ls-87 [000] ...1. 8067.616115: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./set_graph_notrace"
ls-87 [000] ...1. 8067.616122: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./set_graph_function"
ls-87 [000] ...1. 8067.616129: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./set_ftrace_notrace"
ls-87 [000] ...1. 8067.616135: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./set_ftrace_filter"
ls-87 [000] ...1. 8067.616143: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./touched_functions"
ls-87 [000] ...1. 8067.616237: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./enabled_functions"
ls-87 [000] ...1. 8067.616245: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./available_filter_functions"
ls-87 [000] ...1. 8067.616253: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./set_ftrace_notrace_pid"
Link: https://lore.kernel.org/all/169272158234.160970.2446691104240645205.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Using BTF to access the fields of a data structure. You can use this
for accessing the field with '->' or '.' operation with BTF argument.
# echo 't sched_switch next=next->pid vruntime=next->se.vruntime' \
> dynamic_events
# echo 1 > events/tracepoints/sched_switch/enable
# head -n 40 trace | tail
<idle>-0 [000] d..3. 272.565382: sched_switch: (__probestub_sched_switch+0x4/0x10) next=26 vruntime=956533179
kcompactd0-26 [000] d..3. 272.565406: sched_switch: (__probestub_sched_switch+0x4/0x10) next=0 vruntime=0
<idle>-0 [000] d..3. 273.069441: sched_switch: (__probestub_sched_switch+0x4/0x10) next=9 vruntime=956533179
kworker/0:1-9 [000] d..3. 273.069464: sched_switch: (__probestub_sched_switch+0x4/0x10) next=26 vruntime=956579181
kcompactd0-26 [000] d..3. 273.069480: sched_switch: (__probestub_sched_switch+0x4/0x10) next=0 vruntime=0
<idle>-0 [000] d..3. 273.141434: sched_switch: (__probestub_sched_switch+0x4/0x10) next=22 vruntime=956533179
kworker/u2:1-22 [000] d..3. 273.141461: sched_switch: (__probestub_sched_switch+0x4/0x10) next=0 vruntime=0
<idle>-0 [000] d..3. 273.480872: sched_switch: (__probestub_sched_switch+0x4/0x10) next=22 vruntime=956585857
kworker/u2:1-22 [000] d..3. 273.480905: sched_switch: (__probestub_sched_switch+0x4/0x10) next=70 vruntime=959533179
sh-70 [000] d..3. 273.481102: sched_switch: (__probestub_sched_switch+0x4/0x10) next=0 vruntime=0
Link: https://lore.kernel.org/all/169272157251.160970.9318175874130965571.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Since the btf returned from bpf_get_btf_vmlinux() only covers functions in
the vmlinux, BTF argument is not available on the functions in the modules.
Use bpf_find_btf_id() instead of bpf_get_btf_vmlinux()+btf_find_name_kind()
so that BTF argument can find the correct struct btf and btf_type in it.
With this fix, fprobe events can use `$arg*` on module functions as below
# grep nf_log_ip_packet /proc/kallsyms
ffffffffa0005c00 t nf_log_ip_packet [nf_log_syslog]
ffffffffa0005bf0 t __pfx_nf_log_ip_packet [nf_log_syslog]
# echo 'f nf_log_ip_packet $arg*' > dynamic_events
# cat dynamic_events
f:fprobes/nf_log_ip_packet__entry nf_log_ip_packet net=net pf=pf hooknum=hooknum skb=skb in=in out=out loginfo=loginfo prefix=prefix
To support the module's btf which is removable, the struct btf needs to be
ref-counted. So this also records the btf in the traceprobe_parse_context
and returns the refcount when the parse has done.
Link: https://lore.kernel.org/all/169272154223.160970.3507930084247934031.stgit@devnote2/
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Adding support for bpf_get_func_ip helper for uprobe program to return
probed address for both uprobe and return uprobe.
We discussed this in [1] and agreed that uprobe can have special use
of bpf_get_func_ip helper that differs from kprobe.
The kprobe bpf_get_func_ip returns:
- address of the function if probe is attach on function entry
for both kprobe and return kprobe
- 0 if the probe is not attach on function entry
The uprobe bpf_get_func_ip returns:
- address of the probe for both uprobe and return uprobe
The reason for this semantic change is that kernel can't really tell
if the probe user space address is function entry.
The uprobe program is actually kprobe type program attached as uprobe.
One of the consequences of this design is that uprobes do not have its
own set of helpers, but share them with kprobes.
As we need different functionality for bpf_get_func_ip helper for uprobe,
I'm adding the bool value to the bpf_trace_run_ctx, so the helper can
detect that it's executed in uprobe context and call specific code.
The is_uprobe bool is set as true in bpf_prog_run_array_sleepable, which
is currently used only for executing bpf programs in uprobe.
Renaming bpf_prog_run_array_sleepable to bpf_prog_run_array_uprobe
to address that it's only used for uprobes and that it sets the
run_ctx.is_uprobe as suggested by Yafang Shao.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
[1] https://lore.kernel.org/bpf/CAEf4BzZ=xLVkG5eurEuvLU79wAMtwho7ReR+XJAgwhFF4M-7Cg@mail.gmail.com/
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Viktor Malik <vmalik@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230807085956.2344866-2-jolsa@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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Check the target function has non-void retval type and set the correct
fetch type if user doesn't specify it.
If the function returns void, $retval is rejected as below;
# echo 'f unregister_kprobes%return $retval' >> dynamic_events
sh: write error: No such file or directory
# cat error_log
[ 37.488397] trace_fprobe: error: This function returns 'void' type
Command: f unregister_kprobes%return $retval
^
Link: https://lore.kernel.org/all/168507476195.913472.16290308831790216609.stgit@mhiramat.roam.corp.google.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Add the '$arg*' meta fetch argument for function-entry probe events. This
will be expanded to the all arguments of the function and the tracepoint
using BTF function argument information.
e.g.
# echo 'p vfs_read $arg*' >> dynamic_events
# echo 'f vfs_write $arg*' >> dynamic_events
# echo 't sched_overutilized_tp $arg*' >> dynamic_events
# cat dynamic_events
p:kprobes/p_vfs_read_0 vfs_read file=file buf=buf count=count pos=pos
f:fprobes/vfs_write__entry vfs_write file=file buf=buf count=count pos=pos
t:tracepoints/sched_overutilized_tp sched_overutilized_tp rd=rd overutilized=overutilized
Also, single '$arg[0-9]*' will be converted to the BTF function argument.
NOTE: This seems like a wildcard, but a fake one at this moment. This
is just for telling user that this can be expanded to several arguments.
And it is not like other $-vars, you can not use this $arg* as a part of
fetch args, e.g. specifying name "foo=$arg*" and using it in dereferences
"+0($arg*)" will lead a parse error.
Link: https://lore.kernel.org/all/168507475126.913472.18329684401466211816.stgit@mhiramat.roam.corp.google.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Support function or tracepoint parameters by name if BTF support is enabled
and the event is for function entry (this feature can be used with kprobe-
events, fprobe-events and tracepoint probe events.)
Note that the BTF variable syntax does not require a prefix. If it starts
with an alphabetic character or an underscore ('_') without a prefix like
'$' and '%', it is considered as a BTF variable.
If you specify only the BTF variable name, the argument name will also
be the same name instead of 'arg*'.
# echo 'p vfs_read count pos' >> dynamic_events
# echo 'f vfs_write count pos' >> dynamic_events
# echo 't sched_overutilized_tp rd overutilized' >> dynamic_events
# cat dynamic_events
p:kprobes/p_vfs_read_0 vfs_read count=count pos=pos
f:fprobes/vfs_write__entry vfs_write count=count pos=pos
t:tracepoints/sched_overutilized_tp sched_overutilized_tp rd=rd overutilized=overutilized
Link: https://lore.kernel.org/all/168507474014.913472.16963996883278039183.stgit@mhiramat.roam.corp.google.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
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Move trace event parameter fetching code to common parser in
trace_probe.c. This simplifies eprobe's trace-event variable fetching
code by introducing a parse context data structure.
Link: https://lore.kernel.org/all/168507472950.913472.2812253181558471278.stgit@mhiramat.roam.corp.google.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Allow fprobe_events to trace raw tracepoints so that user can trace
tracepoints which don't have traceevent wrappers. This new event is
always available if the fprobe_events is enabled (thus no kconfig),
because the fprobe_events depends on the trace-event and traceporint.
e.g.
# echo 't sched_overutilized_tp' >> dynamic_events
# echo 't 9p_client_req' >> dynamic_events
# cat dynamic_events
t:tracepoints/sched_overutilized_tp sched_overutilized_tp
t:tracepoints/_9p_client_req 9p_client_req
The event name is based on the tracepoint name, but if it is started
with digit character, an underscore '_' will be added.
NOTE: to avoid further confusion, this renames TPARG_FL_TPOINT to
TPARG_FL_TEVENT because this flag is used for eprobe (trace-event probe).
And reuse TPARG_FL_TPOINT for this raw tracepoint probe.
Link: https://lore.kernel.org/all/168507471874.913472.17214624519622959593.stgit@mhiramat.roam.corp.google.com/
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202305020453.afTJ3VVp-lkp@intel.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Add fprobe events for tracing function entry and exit instead of kprobe
events. With this change, we can continue to trace function entry/exit
even if the CONFIG_KPROBES_ON_FTRACE is not available. Since
CONFIG_KPROBES_ON_FTRACE requires the CONFIG_DYNAMIC_FTRACE_WITH_REGS,
it is not available if the architecture only supports
CONFIG_DYNAMIC_FTRACE_WITH_ARGS. And that means kprobe events can not
probe function entry/exit effectively on such architecture.
But this can be solved if the dynamic events supports fprobe events.
The fprobe event is a new dynamic events which is only for the function
(symbol) entry and exit. This event accepts non register fetch arguments
so that user can trace the function arguments and return values.
The fprobe events syntax is here;
f[:[GRP/][EVENT]] FUNCTION [FETCHARGS]
f[MAXACTIVE][:[GRP/][EVENT]] FUNCTION%return [FETCHARGS]
E.g.
# echo 'f vfs_read $arg1' >> dynamic_events
# echo 'f vfs_read%return $retval' >> dynamic_events
# cat dynamic_events
f:fprobes/vfs_read__entry vfs_read arg1=$arg1
f:fprobes/vfs_read__exit vfs_read%return arg1=$retval
# echo 1 > events/fprobes/enable
# head -n 20 trace | tail
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
sh-142 [005] ...1. 448.386420: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.386436: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
sh-142 [005] ...1. 448.386451: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.386458: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
sh-142 [005] ...1. 448.386469: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.386476: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
sh-142 [005] ...1. 448.602073: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.602089: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
Link: https://lore.kernel.org/all/168507469754.913472.6112857614708350210.stgit@mhiramat.roam.corp.google.com/
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/all/202302011530.7vm4O8Ro-lkp@intel.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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When parsing a kprobe event, the return probe always sets both
TPARG_FL_RETURN and TPARG_FL_FENTRY, but this is not useful because
some fetchargs are only for return probe and some others only for
function entry. Make it obviously mutual exclusive.
Link: https://lore.kernel.org/all/168507468731.913472.11354553441385410734.stgit@mhiramat.roam.corp.google.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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All callers of trace_probe_primary_from_call() check the return
value to be non NULL. However, the function returns
list_first_entry(&tpe->probes, ...) which can never be NULL.
Additionally, it does not check for the list being possibly empty,
possibly causing a type confusion on empty lists.
Use list_first_entry_or_null() which solves both problems.
Link: https://lore.kernel.org/linux-trace-kernel/20230128-list-entry-null-check-v1-1-8bde6a3da2ef@diag.uniroma1.it/
Fixes: 60d53e2c3b75 ("tracing/probe: Split trace_event related data from trace_probe")
Signed-off-by: Pietro Borrello <borrello@diag.uniroma1.it>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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print_probe_args is currently inplemented in trace_probe_tmpl.h and
included by *probes, as a result, each probe has an identical copy.
This patch will move it to trace_probe.c as an new API, each probe
calls it to print their args in trace file.
Link: https://lore.kernel.org/all/1672382000-18304-1-git-send-email-chensong_2000@189.cn/
Signed-off-by: Song Chen <chensong_2000@189.cn>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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There are scenes that we want to show the character value of traced
arguments other than a decimal or hexadecimal or string value for debug
convinience. I add a new type named 'char' to do it and a new test case
file named 'kprobe_args_char.tc' to do selftest for char type.
For example:
The to be traced function is 'void demo_func(char type, char *name);', we
can add a kprobe event as follows to show argument values as we want:
echo 'p:myprobe demo_func $arg1:char +0($arg2):char[5]' > kprobe_events
we will get the following trace log:
... myprobe: (demo_func+0x0/0x29) arg1='A' arg2={'b','p','f','1',''}
Link: https://lore.kernel.org/all/20221219110613.367098-1-dolinux.peng@gmail.com/
Signed-off-by: Donglin Peng <dolinux.peng@gmail.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Since uprobe's argument must contain the user-space data, that
should not be converted to kernel symbols. Reject if user
specifies these types on uprobe events. e.g.
/sys/kernel/debug/tracing # echo 'p /bin/sh:10 %ax:symbol' >> uprobe_events
sh: write error: Invalid argument
/sys/kernel/debug/tracing # echo 'p /bin/sh:10 %ax:symstr' >> uprobe_events
sh: write error: Invalid argument
/sys/kernel/debug/tracing # cat error_log
[ 1783.134883] trace_uprobe: error: Unknown type is specified
Command: p /bin/sh:10 %ax:symbol
^
[ 1792.201120] trace_uprobe: error: Unknown type is specified
Command: p /bin/sh:10 %ax:symstr
^
Link: https://lore.kernel.org/all/166679931679.1528100.15540755370726009882.stgit@devnote3/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Add 'symstr' type for storing the kernel symbol as a string data
instead of the symbol address. This allows us to filter the
events by wildcard symbol name.
e.g.
# echo 'e:wqfunc workqueue.workqueue_execute_start symname=$function:symstr' >> dynamic_events
# cat events/eprobes/wqfunc/format
name: wqfunc
ID: 2110
format:
field:unsigned short common_type; offset:0; size:2; signed:0;
field:unsigned char common_flags; offset:2; size:1; signed:0;
field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
field:int common_pid; offset:4; size:4; signed:1;
field:__data_loc char[] symname; offset:8; size:4; signed:1;
print fmt: " symname=\"%s\"", __get_str(symname)
Note that there is already 'symbol' type which just change the
print format (so it still stores the symbol address in the tracing
ring buffer.) On the other hand, 'symstr' type stores the actual
"symbol+offset/size" data as a string.
Link: https://lore.kernel.org/all/166679930847.1528100.4124308529180235965.stgit@devnote3/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
|
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Add the filter option to the event probe. This is useful if user wants
to derive a new event based on the condition of the original event.
E.g.
echo 'e:egroup/stat_runtime_4core sched/sched_stat_runtime \
runtime=$runtime:u32 if cpu < 4' >> ../dynamic_events
Then it can filter the events only on first 4 cores.
Note that the fields used for 'if' must be the fields in the original
events, not eprobe events.
Link: https://lkml.kernel.org/r/165932114513.2850673.2592206685744598080.stgit@devnote2
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
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Show the syntax errors for event probes in error_log file as same as
other dynamic events, so that user can understand what is the problem.
Link: https://lkml.kernel.org/r/165932113556.2850673.3483079297896607612.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Currently, the event probes save the type of the event they are attached
to when recording the event. For example:
# echo 'e:switch sched/sched_switch prev_state=$prev_state prev_prio=$prev_prio next_pid=$next_pid next_prio=$next_prio' > dynamic_events
# cat events/eprobes/switch/format
name: switch
ID: 1717
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:unsigned int __probe_type; offset:8; size:4; signed:0;
field:u64 prev_state; offset:12; size:8; signed:0;
field:u64 prev_prio; offset:20; size:8; signed:0;
field:u64 next_pid; offset:28; size:8; signed:0;
field:u64 next_prio; offset:36; size:8; signed:0;
print fmt: "(%u) prev_state=0x%Lx prev_prio=0x%Lx next_pid=0x%Lx next_prio=0x%Lx", REC->__probe_type, REC->prev_state, REC->prev_prio, REC->next_pid, REC->next_prio
The __probe_type adds 4 bytes to every event.
One of the reasons for creating eprobes is to limit what is traced in an
event to be able to limit what is written into the ring buffer. Having
this redundant 4 bytes to every event takes away from this.
The event that is recorded can be retrieved from the event probe itself,
that is available when the trace is happening. For user space tools, it
could simply read the dynamic_event file to find the event they are for.
So there is really no reason to write this information into the ring
buffer for every event.
Link: https://lkml.kernel.org/r/20220218190057.2f5a19a8@gandalf.local.home
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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