<feed xmlns='http://www.w3.org/2005/Atom'>
<title>user/sven/linux.git/kernel/trace, branch v6.1.148</title>
<subtitle>Linux Kernel
</subtitle>
<id>https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v6.1.148</id>
<link rel='self' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v6.1.148'/>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/'/>
<updated>2025-08-15T10:05:02Z</updated>
<entry>
<title>kernel: trace: preemptirq_delay_test: use offstack cpu mask</title>
<updated>2025-08-15T10:05:02Z</updated>
<author>
<name>Arnd Bergmann</name>
<email>arnd@arndb.de</email>
</author>
<published>2025-06-20T11:12:12Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=0425e67b95432f5bb575e7796a6f8420a425b35b'/>
<id>urn:sha1:0425e67b95432f5bb575e7796a6f8420a425b35b</id>
<content type='text'>
[ Upstream commit adc353c0bfb243ebfd29b6222fa3bf149169a6de ]

A CPU mask on the stack is broken for large values of CONFIG_NR_CPUS:

kernel/trace/preemptirq_delay_test.c: In function ‘preemptirq_delay_run’:
kernel/trace/preemptirq_delay_test.c:143:1: error: the frame size of 8512 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]

Fall back to dynamic allocation here.

Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Song Chen &lt;chensong_2000@189.cn&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Link: https://lore.kernel.org/20250620111215.3365305-1-arnd@kernel.org
Fixes: 4b9091e1c194 ("kernel: trace: preemptirq_delay_test: add cpu affinity")
Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tracing: Add down_write(trace_event_sem) when adding trace event</title>
<updated>2025-07-24T06:51:48Z</updated>
<author>
<name>Steven Rostedt</name>
<email>rostedt@goodmis.org</email>
</author>
<published>2025-07-19T02:31:58Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=7803b28c9aa8d8bd4e19ebcf5f0db9612b0f333b'/>
<id>urn:sha1:7803b28c9aa8d8bd4e19ebcf5f0db9612b0f333b</id>
<content type='text'>
commit b5e8acc14dcb314a9b61ff19dcd9fdd0d88f70df upstream.

When a module is loaded, it adds trace events defined by the module. It
may also need to modify the modules trace printk formats to replace enum
names with their values.

If two modules are loaded at the same time, the adding of the event to the
ftrace_events list can corrupt the walking of the list in the code that is
modifying the printk format strings and crash the kernel.

The addition of the event should take the trace_event_sem for write while
it adds the new event.

Also add a lockdep_assert_held() on that semaphore in
__trace_add_event_dirs() as it iterates the list.

Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Acked-by: Masami Hiramatsu (Google) &lt;mhiramat@kernel.org&gt;
Link: https://lore.kernel.org/20250718223158.799bfc0c@batman.local.home
Reported-by: Fusheng Huang(黄富生)  &lt;Fusheng.Huang@luxshare-ict.com&gt;
Closes: https://lore.kernel.org/all/20250717105007.46ccd18f@batman.local.home/
Fixes: 110bf2b764eb6 ("tracing: add protection around module events unload")
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>ftrace: Fix UAF when lookup kallsym after ftrace disabled</title>
<updated>2025-06-27T10:07:30Z</updated>
<author>
<name>Ye Bin</name>
<email>yebin10@huawei.com</email>
</author>
<published>2025-05-29T11:19:54Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=03a162933c4a03b9f1a84f7d8482903c7e1e11bb'/>
<id>urn:sha1:03a162933c4a03b9f1a84f7d8482903c7e1e11bb</id>
<content type='text'>
commit f914b52c379c12288b7623bb814d0508dbe7481d upstream.

The following issue happens with a buggy module:

BUG: unable to handle page fault for address: ffffffffc05d0218
PGD 1bd66f067 P4D 1bd66f067 PUD 1bd671067 PMD 101808067 PTE 0
Oops: Oops: 0000 [#1] SMP KASAN PTI
Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
RIP: 0010:sized_strscpy+0x81/0x2f0
RSP: 0018:ffff88812d76fa08 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffffc0601010 RCX: dffffc0000000000
RDX: 0000000000000038 RSI: dffffc0000000000 RDI: ffff88812608da2d
RBP: 8080808080808080 R08: ffff88812608da2d R09: ffff88812608da68
R10: ffff88812608d82d R11: ffff88812608d810 R12: 0000000000000038
R13: ffff88812608da2d R14: ffffffffc05d0218 R15: fefefefefefefeff
FS:  00007fef552de740(0000) GS:ffff8884251c7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffc05d0218 CR3: 00000001146f0000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 &lt;TASK&gt;
 ftrace_mod_get_kallsym+0x1ac/0x590
 update_iter_mod+0x239/0x5b0
 s_next+0x5b/0xa0
 seq_read_iter+0x8c9/0x1070
 seq_read+0x249/0x3b0
 proc_reg_read+0x1b0/0x280
 vfs_read+0x17f/0x920
 ksys_read+0xf3/0x1c0
 do_syscall_64+0x5f/0x2e0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

The above issue may happen as follows:
(1) Add kprobe tracepoint;
(2) insmod test.ko;
(3)  Module triggers ftrace disabled;
(4) rmmod test.ko;
(5) cat /proc/kallsyms; --&gt; Will trigger UAF as test.ko already removed;
ftrace_mod_get_kallsym()
...
strscpy(module_name, mod_map-&gt;mod-&gt;name, MODULE_NAME_LEN);
...

The problem is when a module triggers an issue with ftrace and
sets ftrace_disable. The ftrace_disable is set when an anomaly is
discovered and to prevent any more damage, ftrace stops all text
modification. The issue that happened was that the ftrace_disable stops
more than just the text modification.

When a module is loaded, its init functions can also be traced. Because
kallsyms deletes the init functions after a module has loaded, ftrace
saves them when the module is loaded and function tracing is enabled. This
allows the output of the function trace to show the init function names
instead of just their raw memory addresses.

When a module is removed, ftrace_release_mod() is called, and if
ftrace_disable is set, it just returns without doing anything more. The
problem here is that it leaves the mod_list still around and if kallsyms
is called, it will call into this code and access the module memory that
has already been freed as it will return:

  strscpy(module_name, mod_map-&gt;mod-&gt;name, MODULE_NAME_LEN);

Where the "mod" no longer exists and triggers a UAF bug.

Link: https://lore.kernel.org/all/20250523135452.626d8dcd@gandalf.local.home/

Cc: stable@vger.kernel.org
Fixes: aba4b5c22cba ("ftrace: Save module init functions kallsyms symbols for tracing")
Link: https://lore.kernel.org/20250529111955.2349189-2-yebin@huaweicloud.com
Signed-off-by: Ye Bin &lt;yebin10@huawei.com&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>bpf: Fix WARN() in get_bpf_raw_tp_regs</title>
<updated>2025-06-27T10:07:11Z</updated>
<author>
<name>Tao Chen</name>
<email>chen.dylane@linux.dev</email>
</author>
<published>2025-05-13T04:27:47Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=e167414beabb1e941fe563a96becc98627d5bdf6'/>
<id>urn:sha1:e167414beabb1e941fe563a96becc98627d5bdf6</id>
<content type='text'>
[ Upstream commit 3880cdbed1c4607e378f58fa924c5d6df900d1d3 ]

syzkaller reported an issue:

WARNING: CPU: 3 PID: 5971 at kernel/trace/bpf_trace.c:1861 get_bpf_raw_tp_regs+0xa4/0x100 kernel/trace/bpf_trace.c:1861
Modules linked in:
CPU: 3 UID: 0 PID: 5971 Comm: syz-executor205 Not tainted 6.15.0-rc5-syzkaller-00038-g707df3375124 #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:get_bpf_raw_tp_regs+0xa4/0x100 kernel/trace/bpf_trace.c:1861
RSP: 0018:ffffc90003636fa8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000003 RCX: ffffffff81c6bc4c
RDX: ffff888032efc880 RSI: ffffffff81c6bc83 RDI: 0000000000000005
RBP: ffff88806a730860 R08: 0000000000000005 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000000 R12: 0000000000000004
R13: 0000000000000001 R14: ffffc90003637008 R15: 0000000000000900
FS:  0000000000000000(0000) GS:ffff8880d6cdf000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7baee09130 CR3: 0000000029f5a000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 &lt;TASK&gt;
 ____bpf_get_stack_raw_tp kernel/trace/bpf_trace.c:1934 [inline]
 bpf_get_stack_raw_tp+0x24/0x160 kernel/trace/bpf_trace.c:1931
 bpf_prog_ec3b2eefa702d8d3+0x43/0x47
 bpf_dispatcher_nop_func include/linux/bpf.h:1316 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2363 [inline]
 bpf_trace_run3+0x23f/0x5a0 kernel/trace/bpf_trace.c:2405
 __bpf_trace_mmap_lock_acquire_returned+0xfc/0x140 include/trace/events/mmap_lock.h:47
 __traceiter_mmap_lock_acquire_returned+0x79/0xc0 include/trace/events/mmap_lock.h:47
 __do_trace_mmap_lock_acquire_returned include/trace/events/mmap_lock.h:47 [inline]
 trace_mmap_lock_acquire_returned include/trace/events/mmap_lock.h:47 [inline]
 __mmap_lock_do_trace_acquire_returned+0x138/0x1f0 mm/mmap_lock.c:35
 __mmap_lock_trace_acquire_returned include/linux/mmap_lock.h:36 [inline]
 mmap_read_trylock include/linux/mmap_lock.h:204 [inline]
 stack_map_get_build_id_offset+0x535/0x6f0 kernel/bpf/stackmap.c:157
 __bpf_get_stack+0x307/0xa10 kernel/bpf/stackmap.c:483
 ____bpf_get_stack kernel/bpf/stackmap.c:499 [inline]
 bpf_get_stack+0x32/0x40 kernel/bpf/stackmap.c:496
 ____bpf_get_stack_raw_tp kernel/trace/bpf_trace.c:1941 [inline]
 bpf_get_stack_raw_tp+0x124/0x160 kernel/trace/bpf_trace.c:1931
 bpf_prog_ec3b2eefa702d8d3+0x43/0x47

Tracepoint like trace_mmap_lock_acquire_returned may cause nested call
as the corner case show above, which will be resolved with more general
method in the future. As a result, WARN_ON_ONCE will be triggered. As
Alexei suggested, remove the WARN_ON_ONCE first.

Fixes: 9594dc3c7e71 ("bpf: fix nested bpf tracepoints with per-cpu data")
Reported-by: syzbot+45b0c89a0fc7ae8dbadc@syzkaller.appspotmail.com
Suggested-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Tao Chen &lt;chen.dylane@linux.dev&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Link: https://lore.kernel.org/bpf/20250513042747.757042-1-chen.dylane@linux.dev

Closes: https://lore.kernel.org/bpf/8bc2554d-1052-4922-8832-e0078a033e1d@gmail.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tracing: Fix error handling in event_trigger_parse()</title>
<updated>2025-06-27T10:07:10Z</updated>
<author>
<name>Miaoqian Lin</name>
<email>linmq006@gmail.com</email>
</author>
<published>2025-05-07T14:53:07Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=f6007590cc7642c635bcf51a2cc0d83edb756dc3'/>
<id>urn:sha1:f6007590cc7642c635bcf51a2cc0d83edb756dc3</id>
<content type='text'>
[ Upstream commit c5dd28e7fb4f63475b50df4f58311df92939d011 ]

According to trigger_data_alloc() doc, trigger_data_free() should be
used to free an event_trigger_data object. This fixes a mismatch introduced
when kzalloc was replaced with trigger_data_alloc without updating
the corresponding deallocation calls.

Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Tom Zanussi &lt;zanussi@kernel.org&gt;
Link: https://lore.kernel.org/20250507145455.944453325@goodmis.org
Link: https://lore.kernel.org/20250318112737.4174-1-linmq006@gmail.com
Fixes: e1f187d09e11 ("tracing: Have existing event_command.parse() implementations use helpers")
Signed-off-by: Miaoqian Lin &lt;linmq006@gmail.com&gt;
[ SDR: Changed event_trigger_alloc/free() to trigger_data_alloc/free() ]
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tracing: Rename event_trigger_alloc() to trigger_data_alloc()</title>
<updated>2025-06-27T10:07:10Z</updated>
<author>
<name>Steven Rostedt</name>
<email>rostedt@goodmis.org</email>
</author>
<published>2025-05-07T14:53:06Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=535760629970add51f30a87cacb2db42aa0cb79c'/>
<id>urn:sha1:535760629970add51f30a87cacb2db42aa0cb79c</id>
<content type='text'>
[ Upstream commit f2947c4b7d0f235621c5daf78aecfbd6e22c05e5 ]

The function event_trigger_alloc() creates an event_trigger_data
descriptor and states that it needs to be freed via event_trigger_free().
This is incorrect, it needs to be freed by trigger_data_free() as
event_trigger_free() adds ref counting.

Rename event_trigger_alloc() to trigger_data_alloc() and state that it
needs to be freed via trigger_data_free(). This naming convention
was introducing bugs.

Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Tom Zanussi &lt;zanussi@kernel.org&gt;
Link: https://lore.kernel.org/20250507145455.776436410@goodmis.org
Fixes: 86599dbe2c527 ("tracing: Add helper functions to simplify event_command.parse() callback handling")
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tracing: Fix compilation warning on arm32</title>
<updated>2025-06-27T10:07:04Z</updated>
<author>
<name>Pan Taixi</name>
<email>pantaixi@huaweicloud.com</email>
</author>
<published>2025-05-26T01:37:31Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=df1ff1abf3cddb4717fa219a092152f28f45af3d'/>
<id>urn:sha1:df1ff1abf3cddb4717fa219a092152f28f45af3d</id>
<content type='text'>
commit 2fbdb6d8e03b70668c0876e635506540ae92ab05 upstream.

On arm32, size_t is defined to be unsigned int, while PAGE_SIZE is
unsigned long. This hence triggers a compilation warning as min()
asserts the type of two operands to be equal. Casting PAGE_SIZE to size_t
solves this issue and works on other target architectures as well.

Compilation warning details:

kernel/trace/trace.c: In function 'tracing_splice_read_pipe':
./include/linux/minmax.h:20:28: warning: comparison of distinct pointer types lacks a cast
  (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                            ^
./include/linux/minmax.h:26:4: note: in expansion of macro '__typecheck'
   (__typecheck(x, y) &amp;&amp; __no_side_effects(x, y))
    ^~~~~~~~~~~

...

kernel/trace/trace.c:6771:8: note: in expansion of macro 'min'
        min((size_t)trace_seq_used(&amp;iter-&gt;seq),
        ^~~

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20250526013731.1198030-1-pantaixi@huaweicloud.com
Fixes: f5178c41bb43 ("tracing: Fix oob write in trace_seq_to_buffer()")
Reviewed-by: Jeongjun Park &lt;aha310510@gmail.com&gt;
Signed-off-by: Pan Taixi &lt;pantaixi@huaweicloud.com&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>tracing: Mark binary printing functions with __printf() attribute</title>
<updated>2025-06-04T12:40:03Z</updated>
<author>
<name>Andy Shevchenko</name>
<email>andriy.shevchenko@linux.intel.com</email>
</author>
<published>2025-03-21T14:40:49Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=6707f9749deb9d804cf64b3027480d698424f4fd'/>
<id>urn:sha1:6707f9749deb9d804cf64b3027480d698424f4fd</id>
<content type='text'>
[ Upstream commit 196a062641fe68d9bfe0ad36b6cd7628c99ad22c ]

Binary printing functions are using printf() type of format, and compiler
is not happy about them as is:

kernel/trace/trace.c:3292:9: error: function ‘trace_vbprintk’ might be a candidate for ‘gnu_printf’ format attribute [-Werror=suggest-attribute=format]
kernel/trace/trace_seq.c:182:9: error: function ‘trace_seq_bprintf’ might be a candidate for ‘gnu_printf’ format attribute [-Werror=suggest-attribute=format]

Fix the compilation errors by adding __printf() attribute.

While at it, move existing __printf() attributes from the implementations
to the declarations. IT also fixes incorrect attribute parameters that are
used for trace_array_printk().

Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Reviewed-by: Kees Cook &lt;kees@kernel.org&gt;
Reviewed-by: Petr Mladek &lt;pmladek@suse.com&gt;
Link: https://lore.kernel.org/r/20250321144822.324050-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Petr Mladek &lt;pmladek@suse.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>ftrace: Fix preemption accounting for stacktrace filter command</title>
<updated>2025-05-22T12:10:05Z</updated>
<author>
<name>pengdonglin</name>
<email>pengdonglin@xiaomi.com</email>
</author>
<published>2025-05-12T09:42:46Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=cbe20c2c83313ecc48b3011866b2bfe002a74f79'/>
<id>urn:sha1:cbe20c2c83313ecc48b3011866b2bfe002a74f79</id>
<content type='text'>
commit 11aff32439df6ca5b3b891b43032faf88f4a6a29 upstream.

The preemption count of the stacktrace filter command to trace ksys_read
is consistently incorrect:

$ echo ksys_read:stacktrace &gt; set_ftrace_filter

   &lt;...&gt;-453     [004] ...1.    38.308956: &lt;stack trace&gt;
=&gt; ksys_read
=&gt; do_syscall_64
=&gt; entry_SYSCALL_64_after_hwframe

The root cause is that the trace framework disables preemption when
invoking the filter command callback in function_trace_probe_call:

   preempt_disable_notrace();
   probe_ops-&gt;func(ip, parent_ip, probe_opsbe-&gt;tr, probe_ops, probe-&gt;data);
   preempt_enable_notrace();

Use tracing_gen_ctx_dec() to account for the preempt_disable_notrace(),
which will output the correct preemption count:

$ echo ksys_read:stacktrace &gt; set_ftrace_filter

   &lt;...&gt;-410     [006] .....    31.420396: &lt;stack trace&gt;
=&gt; ksys_read
=&gt; do_syscall_64
=&gt; entry_SYSCALL_64_after_hwframe

Cc: stable@vger.kernel.org
Fixes: 36590c50b2d07 ("tracing: Merge irqflags + preempt counter.")
Link: https://lore.kernel.org/20250512094246.1167956-2-dolinux.peng@gmail.com
Signed-off-by: pengdonglin &lt;dolinux.peng@gmail.com&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>ftrace: Fix preemption accounting for stacktrace trigger command</title>
<updated>2025-05-22T12:10:05Z</updated>
<author>
<name>pengdonglin</name>
<email>pengdonglin@xiaomi.com</email>
</author>
<published>2025-05-12T09:42:45Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=c4edc834d2c0bba168cc5dbd0e0943f47856f7c6'/>
<id>urn:sha1:c4edc834d2c0bba168cc5dbd0e0943f47856f7c6</id>
<content type='text'>
commit e333332657f615ac2b55aa35565c4a882018bbe9 upstream.

When using the stacktrace trigger command to trace syscalls, the
preemption count was consistently reported as 1 when the system call
event itself had 0 (".").

For example:

root@ubuntu22-vm:/sys/kernel/tracing/events/syscalls/sys_enter_read
$ echo stacktrace &gt; trigger
$ echo 1 &gt; enable

    sshd-416     [002] .....   232.864910: sys_read(fd: a, buf: 556b1f3221d0, count: 8000)
    sshd-416     [002] ...1.   232.864913: &lt;stack trace&gt;
 =&gt; ftrace_syscall_enter
 =&gt; syscall_trace_enter
 =&gt; do_syscall_64
 =&gt; entry_SYSCALL_64_after_hwframe

The root cause is that the trace framework disables preemption in __DO_TRACE before
invoking the trigger callback.

Use the tracing_gen_ctx_dec() that will accommodate for the increase of
the preemption count in __DO_TRACE when calling the callback. The result
is the accurate reporting of:

    sshd-410     [004] .....   210.117660: sys_read(fd: 4, buf: 559b725ba130, count: 40000)
    sshd-410     [004] .....   210.117662: &lt;stack trace&gt;
 =&gt; ftrace_syscall_enter
 =&gt; syscall_trace_enter
 =&gt; do_syscall_64
 =&gt; entry_SYSCALL_64_after_hwframe

Cc: stable@vger.kernel.org
Fixes: ce33c845b030c ("tracing: Dump stacktrace trigger to the corresponding instance")
Link: https://lore.kernel.org/20250512094246.1167956-1-dolinux.peng@gmail.com
Signed-off-by: pengdonglin &lt;dolinux.peng@gmail.com&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
</feed>
