[for-linus][PATCH 0/4] tracing: Fixes for v6.19

[for-linus][PATCH 0/4] tracing: Fixes for v6.19

[Steven Rostedt]

tracing fixes for v6.19:

- Add Documentation/core-api/tracepoint.rst to TRACING in MAINTAINERS file

  Updates to the tracepoint.rst document should be reviewed by the
  tracing maintainers.

- Fix warning triggered by perf attaching to synthetic events

  The synthetic events do not add a function to be registered when
  perf attaches to them. This causes a warning when perf registers
  a synthetic event and passes a NULL pointer to the tracepoint register
  function. Ideally synthetic events should be updated to work with
  perf, but as that's a feature and not a bug fix, simply now return
  -ENODEV when perf tries to register an event that has a NULL pointer
  for its function. This no longer causes a kernel warning and simply
  causes the perf code to fail with an error message.

- Fix 32bit overflow in option flag test

  The option's flags changed from 32 bits in size to 64 bits in size.
  Fix one of the places that shift 1 by the option bit number to
  to be 1ULL.

- Fix the output of printing the direct jmp functions

  The enabled_functions that shows how functions are being attached by
  ftrace wasn't updated to accommodate the new direct jmp trampolines
  that set the LSB of the pointer, and outputs garbage. Update the
  output to handle the direct jmp trampolines.

  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace/fixes

Head SHA1: 39263f986da55c5b7bc328c757fe378a6a41799d


Darrick J. Wong (1):
      tracing: Fix UBSAN warning in __remove_instance()

Lukas Bulwahn (1):
      MAINTAINERS: add tracepoint core-api doc files to TRACING

Menglong Dong (1):
      ftrace: Fix address for jmp mode in t_show()

Steven Rostedt (1):
      tracing: Do not register unsupported perf events

----
 MAINTAINERS                 | 1 +
 kernel/trace/ftrace.c       | 7 +++++--
 kernel/trace/trace.c        | 2 +-
 kernel/trace/trace_events.c | 2 ++
 4 files changed, 9 insertions(+), 3 deletions(-)

[for-linus][PATCH 1/4] MAINTAINERS: add tracepoint core-api doc files to TRACING

[Steven Rostedt]

From: Lukas Bulwahn <lukas.bulwahn@redhat.com>

The files in Documentation/core-api/ are by virtue of their top-level
directory part of the Documentation section in MAINTAINERS. Each file in
Documentation/core-api/ should however also have a further section in
MAINTAINERS it belongs to, which fits to the technical area of the
documented API in that file.

The tracepoint.rst provides some explanation to tracepoints defined in
selected files under include/trace/events/, which itself is part of the
TRACING section.

So, add this core-api document to TRACING.

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251105092428.153378-1-lukas.bulwahn@redhat.com
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 MAINTAINERS | 1 +
 1 file changed, 1 insertion(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 5b11839cba9d..8e90454bb817 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26464,6 +26464,7 @@ L:	linux-trace-kernel@vger.kernel.org
 S:	Maintained
 Q:	https://patchwork.kernel.org/project/linux-trace-kernel/list/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
+F:	Documentation/core-api/tracepoint.rst
 F:	Documentation/trace/*
 F:	fs/tracefs/
 F:	include/linux/trace*.h
-- 
2.51.0

[for-linus][PATCH 2/4] tracing: Do not register unsupported perf events

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

Synthetic events currently do not have a function to register perf events.
This leads to calling the tracepoint register functions with a NULL
function pointer which triggers:

 ------------[ cut here ]------------
 WARNING: kernel/tracepoint.c:175 at tracepoint_add_func+0x357/0x370, CPU#2: perf/2272
 Modules linked in: kvm_intel kvm irqbypass
 CPU: 2 UID: 0 PID: 2272 Comm: perf Not tainted 6.18.0-ftest-11964-ge022764176fc-dirty #323 PREEMPTLAZY
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
 RIP: 0010:tracepoint_add_func+0x357/0x370
 Code: 28 9c e8 4c 0b f5 ff eb 0f 4c 89 f7 48 c7 c6 80 4d 28 9c e8 ab 89 f4 ff 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc <0f> 0b 49 c7 c6 ea ff ff ff e9 ee fe ff ff 0f 0b e9 f9 fe ff ff 0f
 RSP: 0018:ffffabc0c44d3c40 EFLAGS: 00010246
 RAX: 0000000000000001 RBX: ffff9380aa9e4060 RCX: 0000000000000000
 RDX: 000000000000000a RSI: ffffffff9e1d4a98 RDI: ffff937fcf5fd6c8
 RBP: 0000000000000001 R08: 0000000000000007 R09: ffff937fcf5fc780
 R10: 0000000000000003 R11: ffffffff9c193910 R12: 000000000000000a
 R13: ffffffff9e1e5888 R14: 0000000000000000 R15: ffffabc0c44d3c78
 FS:  00007f6202f5f340(0000) GS:ffff93819f00f000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055d3162281a8 CR3: 0000000106a56003 CR4: 0000000000172ef0
 Call Trace:
  <TASK>
  tracepoint_probe_register+0x5d/0x90
  synth_event_reg+0x3c/0x60
  perf_trace_event_init+0x204/0x340
  perf_trace_init+0x85/0xd0
  perf_tp_event_init+0x2e/0x50
  perf_try_init_event+0x6f/0x230
  ? perf_event_alloc+0x4bb/0xdc0
  perf_event_alloc+0x65a/0xdc0
  __se_sys_perf_event_open+0x290/0x9f0
  do_syscall_64+0x93/0x7b0
  ? entry_SYSCALL_64_after_hwframe+0x76/0x7e
  ? trace_hardirqs_off+0x53/0xc0
  entry_SYSCALL_64_after_hwframe+0x76/0x7e

Instead, have the code return -ENODEV, which doesn't warn and has perf
error out with:

 # perf record -e synthetic:futex_wait
Error:
The sys_perf_event_open() syscall returned with 19 (No such device) for event (synthetic:futex_wait).
"dmesg | grep -i perf" may provide additional information.

Ideally perf should support synthetic events, but for now just fix the
warning. The support can come later.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://patch.msgid.link/20251216182440.147e4453@gandalf.local.home
Fixes: 4b147936fa509 ("tracing: Add support for 'synthetic' events")
Reported-by: Ian Rogers <irogers@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_events.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index b16a5a158040..76067529db61 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -700,6 +700,8 @@ int trace_event_reg(struct trace_event_call *call,
 
 #ifdef CONFIG_PERF_EVENTS
 	case TRACE_REG_PERF_REGISTER:
+		if (!call->class->perf_probe)
+			return -ENODEV;
 		return tracepoint_probe_register(call->tp,
 						 call->class->perf_probe,
 						 call);
-- 
2.51.0

[for-linus][PATCH 3/4] tracing: Fix UBSAN warning in __remove_instance()

[Steven Rostedt]

From: "Darrick J. Wong" <djwong@kernel.org>

xfs/558 triggers the following UBSAN warning:

 ------------[ cut here ]------------
 UBSAN: shift-out-of-bounds in kernel/trace/trace.c:10510:10
 shift exponent 32 is too large for 32-bit type 'int'
 CPU: 1 UID: 0 PID: 888674 Comm: rmdir Not tainted 6.19.0-rc1-xfsx #rc1 PREEMPT(lazy)  dbf607ef4c142c563f76d706e71af9731d7b9c90
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-4.module+el8.8.0+21164+ed375313 04/01/2014
 Call Trace:
  <TASK>
  dump_stack_lvl+0x4a/0x70
  ubsan_epilogue+0x5/0x2b
  __ubsan_handle_shift_out_of_bounds.cold+0x5e/0x113
  __remove_instance.part.0.constprop.0.cold+0x18/0x26f
  instance_rmdir+0xf3/0x110
  tracefs_syscall_rmdir+0x4d/0x90
  vfs_rmdir+0x139/0x230
  do_rmdir+0x143/0x230
  __x64_sys_rmdir+0x1d/0x20
  do_syscall_64+0x44/0x230
  entry_SYSCALL_64_after_hwframe+0x4b/0x53
 RIP: 0033:0x7f7ae8e51f17
 Code: f0 ff ff 73 01 c3 48 8b 0d de 2e 0e 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 54 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 b1 2e 0e 00 f7 d8 64 89 02 b8
 RSP: 002b:00007ffd90743f08 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
 RAX: ffffffffffffffda RBX: 00007ffd907440f8 RCX: 00007f7ae8e51f17
 RDX: 00007f7ae8f3c5c0 RSI: 00007ffd90744a21 RDI: 00007ffd90744a21
 RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
 R10: 00007f7ae8f35ac0 R11: 0000000000000246 R12: 00007ffd90744a21
 R13: 0000000000000001 R14: 00007f7ae8f8b000 R15: 000055e5283e6a98
  </TASK>
 ---[ end trace ]---

whilst tearing down an ftrace instance.  TRACE_FLAGS_MAX_SIZE is now 64bit,
so the mask comparison expression must be typecast to a u64 value to
avoid an overflow.  AFAICT, ZEROED_TRACE_FLAGS is already cast to ULL
so this is ok.

Link: https://patch.msgid.link/20251216174950.GA7705@frogsfrogsfrogs
Fixes: bbec8e28cac592 ("tracing: Allow tracer to add more than 32 options")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e575956ef9b5..6f2148df14d9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -10507,7 +10507,7 @@ static int __remove_instance(struct trace_array *tr)
 
 	/* Disable all the flags that were enabled coming in */
 	for (i = 0; i < TRACE_FLAGS_MAX_SIZE; i++) {
-		if ((1 << i) & ZEROED_TRACE_FLAGS)
+		if ((1ULL << i) & ZEROED_TRACE_FLAGS)
 			set_tracer_flag(tr, 1ULL << i, 0);
 	}
 
-- 
2.51.0

[for-linus][PATCH 4/4] ftrace: Fix address for jmp mode in t_show()

[Steven Rostedt]

From: Menglong Dong <menglong8.dong@gmail.com>

The address from ftrace_find_rec_direct() is printed directly in t_show().
This can mislead symbol offsets if it has the "jmp" bit in the last bit.

Fix this by printing the address that returned by ftrace_jmp_get().

Link: https://patch.msgid.link/20251217030053.80343-1-dongml2@chinatelecom.cn
Fixes: 25e4e3565d45 ("ftrace: Introduce FTRACE_OPS_FL_JMP")
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3ec2033c0774..ef2d5dca6f70 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4518,8 +4518,11 @@ static int t_show(struct seq_file *m, void *v)
 			unsigned long direct;
 
 			direct = ftrace_find_rec_direct(rec->ip);
-			if (direct)
-				seq_printf(m, "\n\tdirect-->%pS", (void *)direct);
+			if (direct) {
+				seq_printf(m, "\n\tdirect%s-->%pS",
+					   ftrace_is_jmp(direct) ? "(jmp)" : "",
+					   (void *)ftrace_jmp_get(direct));
+			}
 		}
 	}
 
-- 
2.51.0