| Age | Commit message (Collapse) | Author | Files | Lines |
|---|
|
commit 327e28664307d49ce3fa71ba30dcc0007c270974 upstream.
When setting the funcgraph-args option when function graph tracer is net
enabled, it incorrectly enables it. Worse, it unregisters itself when it
was never registered. Then when it gets enabled again, it will register
itself a second time causing a WARNing.
~# echo 1 > /sys/kernel/tracing/options/funcgraph-args
~# head -20 /sys/kernel/tracing/trace
# tracer: nop
#
# entries-in-buffer/entries-written: 813/26317372 #P:8
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
<idle>-0 [007] d..4. 358.966010: 7) 1.692 us | fetch_next_timer_interrupt(basej=4294981640, basem=357956000000, base_local=0xffff88823c3ae040, base_global=0xffff88823c3af300, tevt=0xffff888100e47cb8);
<idle>-0 [007] d..4. 358.966012: 7) | tmigr_cpu_deactivate(nextexp=357988000000) {
<idle>-0 [007] d..4. 358.966013: 7) | _raw_spin_lock(lock=0xffff88823c3b2320) {
<idle>-0 [007] d..4. 358.966014: 7) 0.981 us | preempt_count_add(val=1);
<idle>-0 [007] d..5. 358.966017: 7) 1.058 us | do_raw_spin_lock(lock=0xffff88823c3b2320);
<idle>-0 [007] d..4. 358.966019: 7) 5.824 us | }
<idle>-0 [007] d..5. 358.966021: 7) | tmigr_inactive_up(group=0xffff888100cb9000, child=0x0, data=0xffff888100e47bc0) {
<idle>-0 [007] d..5. 358.966022: 7) | tmigr_update_events(group=0xffff888100cb9000, child=0x0, data=0xffff888100e47bc0) {
Notice the "tracer: nop" at the top there. The current tracer is the "nop"
tracer, but the content is obviously the function graph tracer.
Enabling function graph tracing will cause it to register again and
trigger a warning in the accounting:
~# echo function_graph > /sys/kernel/tracing/current_tracer
-bash: echo: write error: Device or resource busy
With the dmesg of:
------------[ cut here ]------------
WARNING: CPU: 7 PID: 1095 at kernel/trace/ftrace.c:3509 ftrace_startup_subops+0xc1e/0x1000
Modules linked in: kvm_intel kvm irqbypass
CPU: 7 UID: 0 PID: 1095 Comm: bash Not tainted 6.16.0-rc2-test-00006-gea03de4105d3 #24 PREEMPT
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:ftrace_startup_subops+0xc1e/0x1000
Code: 48 b8 22 01 00 00 00 00 ad de 49 89 84 24 88 01 00 00 8b 44 24 08 89 04 24 e9 c3 f7 ff ff c7 04 24 ed ff ff ff e9 b7 f7 ff ff <0f> 0b c7 04 24 f0 ff ff ff e9 a9 f7 ff ff c7 04 24 f4 ff ff ff e9
RSP: 0018:ffff888133cff948 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 1ffff1102679ff31 RCX: 0000000000000000
RDX: 1ffffffff0b27a60 RSI: ffffffff8593d2f0 RDI: ffffffff85941140
RBP: 00000000000c2041 R08: ffffffffffffffff R09: ffffed1020240221
R10: ffff88810120110f R11: ffffed1020240214 R12: ffffffff8593d2f0
R13: ffffffff8593d300 R14: ffffffff85941140 R15: ffffffff85631100
FS: 00007f7ec6f28740(0000) GS:ffff8882b5251000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7ec6f181c0 CR3: 000000012f1d0005 CR4: 0000000000172ef0
Call Trace:
<TASK>
? __pfx_ftrace_startup_subops+0x10/0x10
? find_held_lock+0x2b/0x80
? ftrace_stub_direct_tramp+0x10/0x10
? ftrace_stub_direct_tramp+0x10/0x10
? trace_preempt_on+0xd0/0x110
? __pfx_trace_graph_entry_args+0x10/0x10
register_ftrace_graph+0x4d2/0x1020
? tracing_reset_online_cpus+0x14b/0x1e0
? __pfx_register_ftrace_graph+0x10/0x10
? ring_buffer_record_enable+0x16/0x20
? tracing_reset_online_cpus+0x153/0x1e0
? __pfx_tracing_reset_online_cpus+0x10/0x10
? __pfx_trace_graph_return+0x10/0x10
graph_trace_init+0xfd/0x160
tracing_set_tracer+0x500/0xa80
? __pfx_tracing_set_tracer+0x10/0x10
? lock_release+0x181/0x2d0
? _copy_from_user+0x26/0xa0
tracing_set_trace_write+0x132/0x1e0
? __pfx_tracing_set_trace_write+0x10/0x10
? ftrace_graph_func+0xcc/0x140
? ftrace_stub_direct_tramp+0x10/0x10
? ftrace_stub_direct_tramp+0x10/0x10
? ftrace_stub_direct_tramp+0x10/0x10
vfs_write+0x1d0/0xe90
? __pfx_vfs_write+0x10/0x10
Have the setting of the funcgraph-args check if function_graph tracer is
the current tracer of the instance, and if not, do nothing, as there's
nothing to do (the option is checked when function_graph tracing starts).
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/20250618073801.057ea636@gandalf.local.home
Fixes: c7a60a733c373 ("ftrace: Have funcgraph-args take affect during tracing")
Closes: https://lore.kernel.org/all/4ab1a7bdd0174ab09c7b0d68cdbff9a4@huawei.com/
Reported-by: Changbin Du <changbin.du@huawei.com>
Tested-by: Changbin Du <changbin.du@huawei.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
The retval and retaddr options for function_graph tracer will add a
comment at the end of a function for both leaf and non leaf functions that
looks like:
__wake_up_common(); /* ret=0x1 */
} /* pick_next_task_fair ret=0x0 */
The function print_graph_retval() adds a newline after the "*/". But if
that's not called, the caller function needs to make sure there's a
newline added.
This is confusing and when the function parameters code was added, it
added a newline even when calling print_graph_retval() as the fact that
the print_graph_retval() function prints a newline isn't obvious.
This caused an extra newline to be printed and that made it fail the
selftests when the retval option was set, as the selftests were not
expecting blank lines being injected into the trace.
Instead of having print_graph_retval() print a newline, just have the
caller always print the newline regardless if it calls print_graph_retval()
or not. This not only fixes this bug, but it also simplifies the code.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250411133015.015ca393@gandalf.local.home
Reported-by: Mark Brown <broonie@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/all/ccc40f2b-4b9e-4abd-8daf-d22fce2a86f0@sirena.org.uk/
Fixes: ff5c9c576e754 ("ftrace: Add support for function argument to graph tracer")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
switching
Kairui reported a UAF issue in print_graph_function_flags() during
ftrace stress testing [1]. This issue can be reproduced if puting a
'mdelay(10)' after 'mutex_unlock(&trace_types_lock)' in s_start(),
and executing the following script:
$ echo function_graph > current_tracer
$ cat trace > /dev/null &
$ sleep 5 # Ensure the 'cat' reaches the 'mdelay(10)' point
$ echo timerlat > current_tracer
The root cause lies in the two calls to print_graph_function_flags
within print_trace_line during each s_show():
* One through 'iter->trace->print_line()';
* Another through 'event->funcs->trace()', which is hidden in
print_trace_fmt() before print_trace_line returns.
Tracer switching only updates the former, while the latter continues
to use the print_line function of the old tracer, which in the script
above is print_graph_function_flags.
Moreover, when switching from the 'function_graph' tracer to the
'timerlat' tracer, s_start only calls graph_trace_close of the
'function_graph' tracer to free 'iter->private', but does not set
it to NULL. This provides an opportunity for 'event->funcs->trace()'
to use an invalid 'iter->private'.
To fix this issue, set 'iter->private' to NULL immediately after
freeing it in graph_trace_close(), ensuring that an invalid pointer
is not passed to other tracers. Additionally, clean up the unnecessary
'iter->private = NULL' during each 'cat trace' when using wakeup and
irqsoff tracers.
[1] https://lore.kernel.org/all/20231112150030.84609-1-ryncsn@gmail.com/
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Zheng Yejian <zhengyejian1@huawei.com>
Link: https://lore.kernel.org/20250320122137.23635-1-wutengda@huaweicloud.com
Fixes: eecb91b9f98d ("tracing: Fix memleak due to race between current_tracer and trace")
Closes: https://lore.kernel.org/all/CAMgjq7BW79KDSCyp+tZHjShSzHsScSiJxn5ffskp-QzVM06fxw@mail.gmail.com/
Reported-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Tengda Wu <wutengda@huaweicloud.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Variable func is not effectively used, so delete it.
kernel/trace/trace_functions_graph.c:925:16: warning: variable ‘func’ set but not used.
This happened because the variable "func" which came from "call->func" was
replaced by "ret_func" coming from "graph_ret->func" but "func" wasn't
removed after the replacement.
Link: https://lore.kernel.org/20250307021412.119107-1-jiapeng.chong@linux.alibaba.com
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=19250
Fixes: ff5c9c576e754 ("ftrace: Add support for function argument to graph tracer")
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Currently, when function_graph is started, it looks at the option
funcgraph-args, and if it is set, it will enable tracing of the arguments.
But if tracing is already running, and the user enables funcgraph-args, it
will have no effect. Instead, it should enable argument tracing when it is
enabled, even if it means disabling the function graph tracing for a short
time in order to do the transition.
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Guo Ren <guoren@kernel.org>
Cc: Donglin Peng <dolinux.peng@gmail.com>
Cc: Zheng Yejian <zhengyejian@huaweicloud.com>
Link: https://lore.kernel.org/20250227185822.978998710@goodmis.org
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Wire up the code to print function arguments in the function graph
tracer. This functionality can be enabled/disabled during runtime with
options/funcgraph-args.
Example usage:
6) | dummy_xmit [dummy](skb = 0x8887c100, dev = 0x872ca000) {
6) | consume_skb(skb = 0x8887c100) {
6) | skb_release_head_state(skb = 0x8887c100) {
6) 0.178 us | sock_wfree(skb = 0x8887c100)
6) 0.627 us | }
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Guo Ren <guoren@kernel.org>
Cc: Donglin Peng <dolinux.peng@gmail.com>
Cc: Zheng Yejian <zhengyejian@huaweicloud.com>
Link: https://lore.kernel.org/20250227185822.810321199@goodmis.org
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Co-developed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
The code was restructured where the function graph notrace code, that
would not trace a function and all its children is done by setting a
NOTRACE flag when the function that is not to be traced is hit.
There's a TRACE_GRAPH_NOTRACE_BIT which defines the bit in the flags and a
TRACE_GRAPH_NOTRACE which is the mask with that bit set. But the
restructuring used TRACE_GRAPH_NOTRACE_BIT when it should have used
TRACE_GRAPH_NOTRACE.
For example:
# cd /sys/kernel/tracing
# echo set_track_prepare stack_trace_save > set_graph_notrace
# echo function_graph > current_tracer
# cat trace
[..]
0) | __slab_free() {
0) | free_to_partial_list() {
0) | arch_stack_walk() {
0) | __unwind_start() {
0) 0.501 us | get_stack_info();
Where a non filter trace looks like:
# echo > set_graph_notrace
# cat trace
0) | free_to_partial_list() {
0) | set_track_prepare() {
0) | stack_trace_save() {
0) | arch_stack_walk() {
0) | __unwind_start() {
Where the filter should look like:
# cat trace
0) | free_to_partial_list() {
0) | _raw_spin_lock_irqsave() {
0) 0.350 us | preempt_count_add();
0) 0.351 us | do_raw_spin_lock();
0) 2.440 us | }
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250208001511.535be150@batman.local.home
Fixes: b84214890a9bc ("function_graph: Move graph notrace bit to shadow stack global var")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
The function graph infrastructure is now generic so that kretprobes,
fprobes and BPF can use it. But there is still some leftover logic that
only the function graph tracer itself uses. This is the calculation of the
calltime and return time of the functions. The calculation of the calltime
has been moved into the function graph tracer and those users that need it
so that it doesn't cause overhead to the other users. But the return
function timestamp was still called.
Instead of just moving the taking of the timestamp into the function graph
trace remove the calltime and rettime completely from the ftrace_graph_ret
structure. Instead, move it into the function graph return entry event
structure and this also moves all the calltime and rettime logic out of
the generic fgraph.c code and into the tracing code that uses it.
This has been reported to decrease the overhead by ~27%.
Link: https://lore.kernel.org/all/Z3aSuql3fnXMVMoM@krava/
Link: https://lore.kernel.org/all/173665959558.1629214.16724136597211810729.stgit@devnote2/
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250121194436.15bdf71a@gandalf.local.home
Reported-by: Jiri Olsa <olsajiri@gmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Pass ftrace_regs to the fgraph_ops::retfunc(). If ftrace_regs is not
available, it passes a NULL instead. User callback function can access
some registers (including return address) via this ftrace_regs.
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/173518992972.391279.14055405490327765506.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Pass ftrace_regs to the fgraph_ops::entryfunc(). If ftrace_regs is not
available, it passes a NULL instead. User callback function can access
some registers (including return address) via this ftrace_regs.
Note that the ftrace_regs can be NULL when the arch does NOT define:
HAVE_DYNAMIC_FTRACE_WITH_ARGS or HAVE_DYNAMIC_FTRACE_WITH_REGS.
More specifically, if HAVE_DYNAMIC_FTRACE_WITH_REGS is defined but
not the HAVE_DYNAMIC_FTRACE_WITH_ARGS, and the ftrace ops used to
register the function callback does not set FTRACE_OPS_FL_SAVE_REGS.
In this case, ftrace_regs can be NULL in user callback.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/173518990044.391279.17406984900626078579.stgit@devnote2
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
The function graph tracer disables interrupts as well as prevents
recursion via NMIs when recording the graph tracer code. There's no reason
to do this today. That disabling goes back to 2008 when the function graph
tracer was first introduced and recursion protection wasn't part of the
code.
Today, there's no reason to disable interrupts or prevent the code from
recursing as the infrastructure can easily handle it.
Before this change:
~# echo function_graph > /sys/kernel/tracing/current_tracer
~# perf stat -r 10 ./hackbench 10
Time: 4.240
Time: 4.236
Time: 4.106
Time: 4.014
Time: 4.314
Time: 3.830
Time: 4.063
Time: 4.323
Time: 3.763
Time: 3.727
Performance counter stats for '/work/c/hackbench 10' (10 runs):
33,937.20 msec task-clock # 7.008 CPUs utilized ( +- 1.85% )
18,220 context-switches # 536.874 /sec ( +- 6.41% )
624 cpu-migrations # 18.387 /sec ( +- 9.07% )
11,319 page-faults # 333.528 /sec ( +- 1.97% )
76,657,643,617 cycles # 2.259 GHz ( +- 0.40% )
141,403,302,768 instructions # 1.84 insn per cycle ( +- 0.37% )
25,518,463,888 branches # 751.932 M/sec ( +- 0.35% )
156,151,050 branch-misses # 0.61% of all branches ( +- 0.63% )
4.8423 +- 0.0892 seconds time elapsed ( +- 1.84% )
After this change:
~# echo function_graph > /sys/kernel/tracing/current_tracer
~# perf stat -r 10 ./hackbench 10
Time: 3.340
Time: 3.192
Time: 3.129
Time: 2.579
Time: 2.589
Time: 2.798
Time: 2.791
Time: 2.955
Time: 3.044
Time: 3.065
Performance counter stats for './hackbench 10' (10 runs):
24,416.30 msec task-clock # 6.996 CPUs utilized ( +- 2.74% )
16,764 context-switches # 686.590 /sec ( +- 5.85% )
469 cpu-migrations # 19.208 /sec ( +- 6.14% )
11,519 page-faults # 471.775 /sec ( +- 1.92% )
53,895,628,450 cycles # 2.207 GHz ( +- 0.52% )
105,552,664,638 instructions # 1.96 insn per cycle ( +- 0.47% )
17,808,672,667 branches # 729.376 M/sec ( +- 0.48% )
133,075,435 branch-misses # 0.75% of all branches ( +- 0.59% )
3.490 +- 0.112 seconds time elapsed ( +- 3.22% )
Also removed unneeded "unlikely()" around the retaddr code.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20241223184941.204074053@goodmis.org
Fixes: 9cd2992f2d6c8 ("fgraph: Have set_graph_notrace only affect function_graph tracer") # Performance only
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing updates from Steven Rostedt:
- Addition of faultable tracepoints
There's a tracepoint attached to both a system call entry and exit.
This location is known to allow page faults. The tracepoints are
called under an rcu_read_lock() which does not allow faults that can
sleep. This limits the ability of tracepoint handlers to page fault
in user space system call parameters. Now these tracepoints have been
made "faultable", allowing the callbacks to fault in user space
parameters and record them.
Note, only the infrastructure has been implemented. The consumers
(perf, ftrace, BPF) now need to have their code modified to allow
faults.
- Fix up of BPF code for the tracepoint faultable logic
- Update tracepoints to use the new static branch API
- Remove trace_*_rcuidle() variants and the SRCU protection they used
- Remove unused TRACE_EVENT_FL_FILTERED logic
- Replace strncpy() with strscpy() and memcpy()
- Use replace per_cpu_ptr(smp_processor_id()) with this_cpu_ptr()
- Fix perf events to not duplicate samples when tracing is enabled
- Replace atomic64_add_return(1, counter) with
atomic64_inc_return(counter)
- Make stack trace buffer 4K instead of PAGE_SIZE
- Remove TRACE_FLAG_IRQS_NOSUPPORT flag as it was never used
- Get the true return address for function tracer when function graph
tracer is also running.
When function_graph trace is running along with function tracer, the
parent function of the function tracer sometimes is
"return_to_handler", which is the function graph trampoline to record
the exit of the function. Use existing logic that calls into the
fgraph infrastructure to find the real return address.
- Remove (un)regfunc pointers out of tracepoint structure
- Added last minute bug fix for setting pending modules in stack
function filter.
echo "write*:mod:ext3" > /sys/kernel/tracing/stack_trace_filter
Would cause a kernel NULL dereference.
- Minor clean ups
* tag 'trace-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (31 commits)
ftrace: Fix regression with module command in stack_trace_filter
tracing: Fix function name for trampoline
ftrace: Get the true parent ip for function tracer
tracing: Remove redundant check on field->field in histograms
bpf: ensure RCU Tasks Trace GP for sleepable raw tracepoint BPF links
bpf: decouple BPF link/attach hook and BPF program sleepable semantics
bpf: put bpf_link's program when link is safe to be deallocated
tracing: Replace strncpy() with strscpy() when copying comm
tracing: Add might_fault() check in __DECLARE_TRACE_SYSCALL
tracing: Fix syscall tracepoint use-after-free
tracing: Introduce tracepoint_is_faultable()
tracing: Introduce tracepoint extended structure
tracing: Remove TRACE_FLAG_IRQS_NOSUPPORT
tracing: Replace multiple deprecated strncpy with memcpy
tracing: Make percpu stack trace buffer invariant to PAGE_SIZE
tracing: Use atomic64_inc_return() in trace_clock_counter()
trace/trace_event_perf: remove duplicate samples on the first tracepoint event
tracing/bpf: Add might_fault check to syscall probes
tracing/perf: Add might_fault check to syscall probes
tracing/ftrace: Add might_fault check to syscall probes
...
|
|
The function call_filter_check_discard() has been removed in the
commit 49e4154f4b16 ("tracing: Remove TRACE_EVENT_FL_FILTERED logic"),
from another topic branch. But when merged together with commit
21e92806d39c6 ("function_graph: Support recording and printing the
function return address") which added another call to
call_filter_check_discard(), it caused the build to fail. Since the
function call_filter_check_discard() is useless, it can simply be removed
regardless of being merged with commit 49e4154f4b16 or not.
Link: https://lore.kernel.org/all/20241010134649.43ed357c@canb.auug.org.au/
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Donglin Peng <dolinux.peng@gmail.com>
Link: https://lore.kernel.org/20241010194020.46192b21@gandalf.local.home
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 21e92806d39c6 ("function_graph: Support recording and printing the function return address")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Simplify return address printing in the function graph tracer by removing
fgraph_extras. Since this feature is only used by the function graph
tracer and the feature flags can directly accessible from the function
graph tracer, fgraph_extras can be removed from the fgraph callback.
Cc: Donglin Peng <dolinux.peng@gmail.com>
Link: https://lore.kernel.org/172857234900.270774.15378354017601069781.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
After commit dcb0b5575d24 ("tracing: Remove TRACE_EVENT_FL_USE_CALL_FILTER
logic"), no one's going to set the TRACE_EVENT_FL_FILTERED or change the
call->filter, so remove related logic.
Link: https://lore.kernel.org/20240911010026.2302849-1-zhengyejian@huaweicloud.com
Signed-off-by: Zheng Yejian <zhengyejian@huaweicloud.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
When using function_graph tracer to analyze the flow of kernel function
execution, it is often necessary to quickly locate the exact line of code
where the call occurs. While this may be easy at times, it can be more
time-consuming when some functions are inlined or the flow is too long.
This feature aims to simplify the process by recording the return address
of traced funcions and printing it when outputing trace logs.
To enhance human readability, the prefix 'ret=' is used for the kernel return
value, while '<-' serves as the prefix for the return address in trace logs to
make it look more like the function tracer.
A new trace option named 'funcgraph-retaddr' has been introduced, and the
existing option 'sym-addr' can be used to control the format of the return
address.
See below logs with both funcgraph-retval and funcgraph-retaddr enabled.
0) | load_elf_binary() { /* <-bprm_execve+0x249/0x600 */
0) | load_elf_phdrs() { /* <-load_elf_binary+0x84/0x1730 */
0) | __kmalloc_noprof() { /* <-load_elf_phdrs+0x4a/0xb0 */
0) 3.657 us | __cond_resched(); /* <-__kmalloc_noprof+0x28c/0x390 ret=0x0 */
0) + 24.335 us | } /* __kmalloc_noprof ret=0xffff8882007f3000 */
0) | kernel_read() { /* <-load_elf_phdrs+0x6c/0xb0 */
0) | rw_verify_area() { /* <-kernel_read+0x2b/0x50 */
0) | security_file_permission() { /* <-kernel_read+0x2b/0x50 */
0) | selinux_file_permission() { /* <-security_file_permission+0x26/0x40 */
0) | __inode_security_revalidate() { /* <-selinux_file_permission+0x6d/0x140 */
0) 2.034 us | __cond_resched(); /* <-__inode_security_revalidate+0x5f/0x80 ret=0x0 */
0) 6.602 us | } /* __inode_security_revalidate ret=0x0 */
0) 2.214 us | avc_policy_seqno(); /* <-selinux_file_permission+0x107/0x140 ret=0x0 */
0) + 16.670 us | } /* selinux_file_permission ret=0x0 */
0) + 20.809 us | } /* security_file_permission ret=0x0 */
0) + 25.217 us | } /* rw_verify_area ret=0x0 */
0) | __kernel_read() { /* <-load_elf_phdrs+0x6c/0xb0 */
0) | ext4_file_read_iter() { /* <-__kernel_read+0x160/0x2e0 */
Then, we can use the faddr2line to locate the source code, for example:
$ ./scripts/faddr2line ./vmlinux load_elf_phdrs+0x6c/0xb0
load_elf_phdrs+0x6c/0xb0:
elf_read at fs/binfmt_elf.c:471
(inlined by) load_elf_phdrs at fs/binfmt_elf.c:531
Link: https://lore.kernel.org/20240915032912.1118397-1-dolinux.peng@gmail.com
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409150605.HgUmU8ea-lkp@intel.com/
Signed-off-by: Donglin Peng <dolinux.peng@gmail.com>
[ Rebased to handle text_delta offsets ]
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
The calltime field in the shadow stack frame is only used by the function
graph tracer and profiler. But now that there's other users of the function
graph infrastructure, this adds overhead and wastes space on the shadow
stack. Move the calltime to the fgraph data storage, where the function
graph and profiler entry functions will save it in its own graph storage and
retrieve it in its exit functions.
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Link: https://lore.kernel.org/20240914214827.096968730@goodmis.org
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
The fgraph "sleep-time" option tells the function graph tracer and the
profiler whether to include the time a function "sleeps" (is scheduled off
the CPU) in its duration for the function. By default it is true, which
means the duration of a function is calculated by the timestamp of when the
function was entered to the timestamp of when it exits.
If the "sleep-time" option is disabled, it needs to remove the time that the
task was not running on the CPU during the function. Currently it is done in
a sched_switch tracepoint probe where it moves the "calltime" (time of entry
of the function) forward by the sleep time calculated. It updates all the
calltime in the shadow stack.
This is time consuming for those users of the function graph tracer that
does not care about the sleep time. Instead, add a "ftrace_sleeptime" to the
task_struct that gets the sleep time added each time the task wakes up. Then
have the function entry save the current "ftrace_sleeptime" and on function
exit, move the calltime forward by the difference of the current
"ftrace_sleeptime" from the saved sleeptime.
This removes one dependency of "calltime" needed to be on the shadow stack.
It also simplifies the code that removes the sleep time of functions.
TODO: Only enable the sched_switch tracepoint when this is needed.
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Link: https://lore.kernel.org/20240914214826.938908568@goodmis.org
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Update the function graph code to modify the function addresses for a
previous boot buffer so that it matches the current kallsyms (note this
does not handle module addresses, yet).
After a reboot, instead of seeing:
# trace-cmd show -B boot_mapped | tail -n30
swapper/0-1 [000] d..2. 56.286470: 0) 0.481 us | 0xffffffff925da5c4();
swapper/0-1 [000] d.... 56.286471: 0) 4.065 us | }
swapper/0-1 [000] d.... 56.286471: 0) 4.920 us | }
swapper/0-1 [000] d..1. 56.286472: 0) | 0xffffffff92536254() {
swapper/0-1 [000] d..1. 56.286472: 0) + 28.974 us | 0xffffffff92534e30();
swapper/0-1 [000] d.... 56.286516: 0) + 43.881 us | }
swapper/0-1 [000] d..1. 56.286517: 0) | 0xffffffff925136c4() {
swapper/0-1 [000] d..1. 56.286518: 0) | 0xffffffff92514a14() {
swapper/0-1 [000] d..1. 56.286518: 0) 6.003 us | 0xffffffff92514200();
swapper/0-1 [000] d.... 56.286529: 0) + 11.510 us | }
swapper/0-1 [000] d.... 56.286529: 0) + 12.895 us | }
swapper/0-1 [000] d.... 56.286530: 0) ! 382.884 us | }
swapper/0-1 [000] d..1. 56.286530: 0) | 0xffffffff92536444() {
swapper/0-1 [000] d..1. 56.286531: 0) | 0xffffffff92536254() {
swapper/0-1 [000] d..1. 56.286531: 0) + 26.335 us | 0xffffffff92534e30();
swapper/0-1 [000] d.... 56.286560: 0) + 29.511 us | }
swapper/0-1 [000] d.... 56.286561: 0) + 30.452 us | }
swapper/0-1 [000] d..1. 56.286562: 0) | 0xffffffff9253c014() {
swapper/0-1 [000] d..1. 56.286562: 0) | 0xffffffff9253bed4() {
swapper/0-1 [000] d..1. 56.286563: 0) + 13.465 us | 0xffffffff92536684();
swapper/0-1 [000] d.... 56.286577: 0) + 14.651 us | }
swapper/0-1 [000] d.... 56.286577: 0) + 15.821 us | }
swapper/0-1 [000] d..1. 56.286578: 0) 0.667 us | 0xffffffff92547074();
swapper/0-1 [000] d..1. 56.286579: 0) 0.453 us | 0xffffffff924f35c4();
swapper/0-1 [000] d.... 56.286580: 0) # 3906.348 us | }
swapper/0-1 [000] d..1. 56.286581: 0) | 0xffffffff92531a14() {
swapper/0-1 [000] d..1. 56.286581: 0) 0.518 us | 0xffffffff92505cb4();
swapper/0-1 [000] d..1. 56.286595: 0) | 0xffffffff92db83c4() {
swapper/0-1 [000] d..1. 56.286596: 0) | 0xffffffff92dec2e4() {
swapper/0-1 [000] d..1. 56.286597: 0) | 0xffffffff92db5304() {
It now shows:
# trace-cmd show -B boot_mapped | tail -n30
swapper/0-1 [000] d..2. 363.079099: 0) 0.483 us | preempt_count_sub();
swapper/0-1 [000] d.... 363.079100: 0) 4.112 us | }
swapper/0-1 [000] d.... 363.079101: 0) 4.979 us | }
swapper/0-1 [000] d..1. 363.079101: 0) | disable_local_APIC() {
swapper/0-1 [000] d..1. 363.079102: 0) + 29.153 us | clear_local_APIC.part.0();
swapper/0-1 [000] d.... 363.079148: 0) + 46.517 us | }
swapper/0-1 [000] d..1. 363.079149: 0) | mcheck_cpu_clear() {
swapper/0-1 [000] d..1. 363.079149: 0) | mce_intel_feature_clear() {
swapper/0-1 [000] d..1. 363.079150: 0) 5.871 us | lmce_supported();
swapper/0-1 [000] d.... 363.079161: 0) + 11.340 us | }
swapper/0-1 [000] d.... 363.079161: 0) + 12.638 us | }
swapper/0-1 [000] d.... 363.079162: 0) ! 383.518 us | }
swapper/0-1 [000] d..1. 363.079162: 0) | lapic_shutdown() {
swapper/0-1 [000] d..1. 363.079163: 0) | disable_local_APIC() {
swapper/0-1 [000] d..1. 363.079163: 0) + 26.144 us | clear_local_APIC.part.0();
swapper/0-1 [000] d.... 363.079192: 0) + 29.424 us | }
swapper/0-1 [000] d.... 363.079192: 0) + 30.376 us | }
swapper/0-1 [000] d..1. 363.079193: 0) | restore_boot_irq_mode() {
swapper/0-1 [000] d..1. 363.079194: 0) | native_restore_boot_irq_mode() {
swapper/0-1 [000] d..1. 363.079194: 0) + 13.863 us | disconnect_bsp_APIC();
swapper/0-1 [000] d.... 363.079209: 0) + 14.933 us | }
swapper/0-1 [000] d.... 363.079209: 0) + 16.009 us | }
swapper/0-1 [000] d..1. 363.079210: 0) 0.694 us | hpet_disable();
swapper/0-1 [000] d..1. 363.079211: 0) 0.511 us | iommu_shutdown_noop();
swapper/0-1 [000] d.... 363.079212: 0) # 3980.260 us | }
swapper/0-1 [000] d..1. 363.079212: 0) | native_machine_emergency_restart() {
swapper/0-1 [000] d..1. 363.079213: 0) 0.495 us | tboot_shutdown();
swapper/0-1 [000] d..1. 363.079230: 0) | acpi_reboot() {
swapper/0-1 [000] d..1. 363.079231: 0) | acpi_reset() {
swapper/0-1 [000] d..1. 363.079232: 0) | acpi_os_write_port() {
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ross Zwisler <zwisler@google.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Link: https://lore.kernel.org/20240813171257.478901820@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
The use of the task->trace_recursion for the logic used for the function
graph no-trace was a bit of an abuse of that variable. Now that there
exists global vars that are per stack for registered graph traces, use
that instead.
Link: https://lore.kernel.org/linux-trace-kernel/171509107907.162236.6564679266777519065.stgit@devnote2
Link: https://lore.kernel.org/linux-trace-kernel/20240603190823.796709456@goodmis.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
The use of the task->trace_recursion for the logic used for the
set_graph_function was a bit of an abuse of that variable. Now that there
exists global vars that are per stack for registered graph traces, use that
instead.
Link: https://lore.kernel.org/linux-trace-kernel/171509105520.162236.10339831553995971290.stgit@devnote2
Link: https://lore.kernel.org/linux-trace-kernel/20240603190823.472955399@goodmis.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Allow for instances to have their own ftrace_ops part of the fgraph_ops
that makes the funtion_graph tracer filter on the set_ftrace_filter file
of the instance and not the top instance.
This uses the new ftrace_startup_subops(), by using graph_ops as the
"manager ops" that defines the callback function and adds the functions
defined by the filters of the ops for each trace instance. The callback
defined by the manager ops will call the registered fgraph ops that were
added to the fgraph_array.
Co-developed with Masami Hiramatsu:
Link: https://lore.kernel.org/linux-trace-kernel/171509102088.162236.15758883237657317789.stgit@devnote2
Link: https://lore.kernel.org/linux-trace-kernel/20240603190822.832946261@goodmis.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Now that function graph tracing can handle more than one user, allow it to
be enabled in the ftrace instances. Note, the filtering of the functions is
still joined by the top level set_ftrace_filter and friends, as well as the
graph and nograph files.
Co-developed with Masami Hiramatsu:
Link: https://lore.kernel.org/linux-trace-kernel/171509099743.162236.1699959255446248163.stgit@devnote2
Link: https://lore.kernel.org/linux-trace-kernel/20240603190822.190630762@goodmis.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Pass the fgraph_ops structure to the function graph callbacks. This will
allow callbacks to add a descriptor to a fgraph_ops private field that wil
be added in the future and use it for the callbacks. This will be useful
when more than one callback can be registered to the function graph tracer.
Co-developed with Masami Hiramatsu:
Link: https://lore.kernel.org/linux-trace-kernel/171509098588.162236.4787930115997357578.stgit@devnote2
Link: https://lore.kernel.org/linux-trace-kernel/20240603190822.035147698@goodmis.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Analyzing system call failures with the function_graph tracer can be a
time-consuming process, particularly when locating the kernel function
that first returns an error in the trace logs. This change aims to
simplify the process by recording the function return value to the
'retval' member of 'ftrace_graph_ret' and printing it when outputting
the trace log.
We have introduced new trace options: funcgraph-retval and
funcgraph-retval-hex. The former controls whether to display the return
value, while the latter controls the display format.
Please note that even if a function's return type is void, a return
value will still be printed. You can simply ignore it.
This patch only establishes the fundamental infrastructure. Subsequent
patches will make this featur |
