[for-next][PATCH 0/5] tracing: last minute changes before pushing

[for-next][PATCH 0/5] tracing: last minute changes before pushing

[Steven Rostedt]

Bah, I had this tested last week before going on PTO and forgot to push
it to my for-next branch. But it's for this merge window.

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
for-next

Head SHA1: f86a1152e15c6b5913f9ec03a2bd97ca70c1ed82


Cong Wang (3):
      tracing: Pass type into tracing_generic_entry_update()
      tracing: Let filter_assign_type() detect FILTER_PTR_STRING
      tracing: Make trace_get_fields() global

Steven Rostedt (VMware) (2):
      ftrace/selftests: Return the skip code when tracing directory not configured in kernel
      ftrace/selftest: Test if set_event/ftrace_pid exists before writing

----
 include/linux/trace_events.h                    |  9 ++++++
 kernel/trace/trace.c                            |  8 +++---
 kernel/trace/trace_event_perf.c                 |  3 +-
 kernel/trace/trace_events.c                     |  8 ------
 kernel/trace/trace_events_filter.c              |  3 ++
 tools/testing/selftests/ftrace/ftracetest       | 38 +++++++++++++++++++++----
 tools/testing/selftests/ftrace/test.d/functions |  4 +--
 7 files changed, 51 insertions(+), 22 deletions(-)

[for-next][PATCH 1/5] ftrace/selftests: Return the skip code when tracing directory not configured in kernel

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

If the kernel is not configured with ftrace enabled, the ftracetest
selftests should return the error code of "4" as that is the kselftests
"skip" code, and not "1" which means an error.

To determine if ftrace is enabled, first the newer "tracefs" is searched for
in /proc/mounts. If it is not found, then "debugfs" is searched for (as old
kernels do not have tracefs). If that is not found, an attempt to mount the
tracefs or debugfs is performed. This is done by seeing first if the
/sys/kernel/tracing directory exists. If it does than tracefs is configured
in the kernel and an attempt to mount it is performed.

If /sys/kernel/tracing does not exist, then /sys/kernel/debug is tested to
see if that directory exists. If it does, then an attempt to mount debugfs
on that directory is performed. If it does not exist, then debugfs is not
configured in the running kernel and the test exits with the skip code.

If either mount fails, then a normal error is returned as they do exist in
the kernel but something went wrong to mount them.

This changes the test to always try the tracefs file system first as it has
been in the kernel for some time now and it is better to test it if it is
available instead of always testing debugfs.

Link: http://lkml.kernel.org/r/20190702062358.7330-1-po-hsu.lin@canonical.com

Reported-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 tools/testing/selftests/ftrace/ftracetest | 38 +++++++++++++++++++----
 1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/ftrace/ftracetest b/tools/testing/selftests/ftrace/ftracetest
index 136387422b00..edf5ea35d2a7 100755
--- a/tools/testing/selftests/ftrace/ftracetest
+++ b/tools/testing/selftests/ftrace/ftracetest
@@ -23,9 +23,15 @@ echo "		            If <dir> is -, all logs output in console only"
 exit $1
 }
 
+# default error
+err_ret=1
+
+# kselftest skip code is 4
+err_skip=4
+
 errexit() { # message
   echo "Error: $1" 1>&2
-  exit 1
+  exit $err_ret
 }
 
 # Ensuring user privilege
@@ -116,11 +122,31 @@ parse_opts() { # opts
 }
 
 # Parameters
-DEBUGFS_DIR=`grep debugfs /proc/mounts | cut -f2 -d' ' | head -1`
-if [ -z "$DEBUGFS_DIR" ]; then
-    TRACING_DIR=`grep tracefs /proc/mounts | cut -f2 -d' ' | head -1`
-else
-    TRACING_DIR=$DEBUGFS_DIR/tracing
+TRACING_DIR=`grep tracefs /proc/mounts | cut -f2 -d' ' | head -1`
+if [ -z "$TRACING_DIR" ]; then
+    DEBUGFS_DIR=`grep debugfs /proc/mounts | cut -f2 -d' ' | head -1`
+    if [ -z "$DEBUGFS_DIR" ]; then
+	# If tracefs exists, then so does /sys/kernel/tracing
+	if [ -d "/sys/kernel/tracing" ]; then
+	    mount -t tracefs nodev /sys/kernel/tracing ||
+	      errexit "Failed to mount /sys/kernel/tracing"
+	    TRACING_DIR="/sys/kernel/tracing"
+	# If debugfs exists, then so does /sys/kernel/debug
+	elif [ -d "/sys/kernel/debug" ]; then
+	    mount -t debugfs nodev /sys/kernel/debug ||
+	      errexit "Failed to mount /sys/kernel/debug"
+	    TRACING_DIR="/sys/kernel/debug/tracing"
+	else
+	    err_ret=$err_skip
+	    errexit "debugfs and tracefs are not configured in this kernel"
+	fi
+    else
+	TRACING_DIR="$DEBUGFS_DIR/tracing"
+    fi
+fi
+if [ ! -d "$TRACING_DIR" ]; then
+    err_ret=$err_skip
+    errexit "ftrace is not configured in this kernel"
 fi
 
 TOP_DIR=`absdir $0`
-- 
2.20.1

[for-next][PATCH 2/5] ftrace/selftest: Test if set_event/ftrace_pid exists before writing

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

While testing on a very old kernel (3.5), the tests failed because the write
to set_event_pid in the setup code, did not exist. The tests themselves
could pass, but the setup failed causing an error.

Other files test for existance before writing to them. Do the same for
set_event_pid and set_ftrace_pid.

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 tools/testing/selftests/ftrace/test.d/functions | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/ftrace/test.d/functions b/tools/testing/selftests/ftrace/test.d/functions
index 779ec11f61bd..1d96c5f7e402 100644
--- a/tools/testing/selftests/ftrace/test.d/functions
+++ b/tools/testing/selftests/ftrace/test.d/functions
@@ -91,8 +91,8 @@ initialize_ftrace() { # Reset ftrace to initial-state
     reset_events_filter
     reset_ftrace_filter
     disable_events
-    echo > set_event_pid	# event tracer is always on
-    echo > set_ftrace_pid
+    [ -f set_event_pid ] && echo > set_event_pid
+    [ -f set_ftrace_pid ] && echo > set_ftrace_pid
     [ -f set_ftrace_filter ] && echo | tee set_ftrace_*
     [ -f set_graph_function ] && echo | tee set_graph_*
     [ -f stack_trace_filter ] && echo > stack_trace_filter
-- 
2.20.1

[for-next][PATCH 3/5] tracing: Pass type into tracing_generic_entry_update()

[Steven Rostedt]

From: Cong Wang <xiyou.wangcong@gmail.com>

All callers of tracing_generic_entry_update() have to initialize
entry->type, so let's just simply move it inside.
Link: http://lkml.kernel.org/r/20190525165802.25944-2-xiyou.wangcong@gmail.com

Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/linux/trace_events.h    | 1 +
 kernel/trace/trace.c            | 8 ++++----
 kernel/trace/trace_event_perf.c | 3 +--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 8a62731673f7..5c6f2a6c8cd2 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -142,6 +142,7 @@ enum print_line_t {
 enum print_line_t trace_handle_return(struct trace_seq *s);
 
 void tracing_generic_entry_update(struct trace_entry *entry,
+				  unsigned short type,
 				  unsigned long flags,
 				  int pc);
 struct trace_event_file;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 77b9c4ca5faa..6b62e1718548 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -743,8 +743,7 @@ trace_event_setup(struct ring_buffer_event *event,
 {
 	struct trace_entry *ent = ring_buffer_event_data(event);
 
-	tracing_generic_entry_update(ent, flags, pc);
-	ent->type = type;
+	tracing_generic_entry_update(ent, type, flags, pc);
 }
 
 static __always_inline struct ring_buffer_event *
@@ -2312,13 +2311,14 @@ enum print_line_t trace_handle_return(struct trace_seq *s)
 EXPORT_SYMBOL_GPL(trace_handle_return);
 
 void
-tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
-			     int pc)
+tracing_generic_entry_update(struct trace_entry *entry, unsigned short type,
+			     unsigned long flags, int pc)
 {
 	struct task_struct *tsk = current;
 
 	entry->preempt_count		= pc & 0xff;
 	entry->pid			= (tsk) ? tsk->pid : 0;
+	entry->type			= type;
 	entry->flags =
 #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
 		(irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 4629a6104474..0892e38ed6fb 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -416,8 +416,7 @@ void perf_trace_buf_update(void *record, u16 type)
 	unsigned long flags;
 
 	local_save_flags(flags);
-	tracing_generic_entry_update(entry, flags, pc);
-	entry->type = type;
+	tracing_generic_entry_update(entry, type, flags, pc);
 }
 NOKPROBE_SYMBOL(perf_trace_buf_update);
 
-- 
2.20.1

[for-next][PATCH 4/5] tracing: Let filter_assign_type() detect FILTER_PTR_STRING

[Steven Rostedt]

From: Cong Wang <xiyou.wangcong@gmail.com>

filter_assign_type() could detect dynamic string and static
string, but not string pointers. Teach filter_assign_type()
to detect string pointers, and this will be needed by trace
event injection code.

BTW, trace event hist uses FILTER_PTR_STRING too.
Link: http://lkml.kernel.org/r/20190525165802.25944-3-xiyou.wangcong@gmail.com

Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_events_filter.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index d3e59312ef40..550e8a0d048a 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1080,6 +1080,9 @@ int filter_assign_type(const char *type)
 	if (strchr(type, '[') && strstr(type, "char"))
 		return FILTER_STATIC_STRING;
 
+	if (strcmp(type, "char *") == 0 || strcmp(type, "const char *") == 0)
+		return FILTER_PTR_STRING;
+
 	return FILTER_OTHER;
 }
 
-- 
2.20.1

[for-next][PATCH 5/5] tracing: Make trace_get_fields() global

[Steven Rostedt]

From: Cong Wang <xiyou.wangcong@gmail.com>

trace_get_fields() is the only way to read tracepoint fields at
run time, as their fields are defined at compile-time with macros.
Make this function visible to all users and it will be used by
trace event injection code to calculate the size of a tracepoint
entry.
Link: http://lkml.kernel.org/r/20190525165802.25944-4-xiyou.wangcong@gmail.com

Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/linux/trace_events.h | 8 ++++++++
 kernel/trace/trace_events.c  | 8 --------
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 5c6f2a6c8cd2..5150436783e8 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -318,6 +318,14 @@ trace_event_name(struct trace_event_call *call)
 		return call->name;
 }
 
+static inline struct list_head *
+trace_get_fields(struct trace_event_call *event_call)
+{
+	if (!event_call->class->get_fields)
+		return &event_call->class->fields;
+	return event_call->class->get_fields(event_call);
+}
+
 struct trace_array;
 struct trace_subsystem_dir;
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index edc72f3b080c..c7506bc81b75 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -70,14 +70,6 @@ static int system_refcount_dec(struct event_subsystem *system)
 #define while_for_each_event_file()		\
 	}
 
-static struct list_head *
-trace_get_fields(struct trace_event_call *event_call)
-{
-	if (!event_call->class->get_fields)
-		return &event_call->class->fields;
-	return event_call->class->get_fields(event_call);
-}
-
 static struct ftrace_event_field *
 __find_event_field(struct list_head *head, char *name)
 {
-- 
2.20.1