[for-next][PATCH 14/21] tracing: Make tp_printk work on syscall tracepoints

Steven Rostedt
2022-04-27T19:38:44Z

From: Jeff Xie <xiehuan09@gmail.com>

Currently the tp_printk option has no effect on syscall tracepoint.
When adding the kernel option parameter tp_printk, then:

echo 1 > /sys/kernel/debug/tracing/events/syscalls/enable

When running any application, no trace information is printed on the
terminal.

Now added printk for syscall tracepoints.

Link: https://lkml.kernel.org/r/20220410145025.681144-1-xiehuan09@gmail.com

Signed-off-by: Jeff Xie <xiehuan09@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace_syscalls.c | 35 +++++++++++------------------------
1 file changed, 11 insertions(+), 24 deletions(-)

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index f755bde42fd0..b69e207012c9 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -154,7 +154,7 @@ print_syscall_enter(struct trace_iterator *iter, int flags,
goto end;

/* parameter types */
- if (tr->trace_flags & TRACE_ITER_VERBOSE)
+ if (tr && tr->trace_flags & TRACE_ITER_VERBOSE)
trace_seq_printf(s, "%s ", entry->types[i]);

/* parameter values */
@@ -296,9 +296,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
struct trace_event_file *trace_file;
struct syscall_trace_enter *entry;
struct syscall_metadata *sys_data;
- struct ring_buffer_event *event;
- struct trace_buffer *buffer;
- unsigned int trace_ctx;
+ struct trace_event_buffer fbuffer;
unsigned long args[6];
int syscall_nr;
int size;
@@ -321,20 +319,16 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)

size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;

- trace_ctx = tracing_gen_ctx();
-
- event = trace_event_buffer_lock_reserve(&buffer, trace_file,
- sys_data->enter_event->event.type, size, trace_ctx);
- if (!event)
+ entry = trace_event_buffer_reserve(&fbuffer, trace_file, size);
+ if (!entry)
return;

- entry = ring_buffer_event_data(event);
+ entry = ring_buffer_event_data(fbuffer.event);
entry->nr = syscall_nr;
syscall_get_arguments(current, regs, args);
memcpy(entry->args, args, sizeof(unsigned long) * sys_data->nb_args);

- event_trigger_unlock_commit(trace_file, buffer, event, entry,
- trace_ctx);
+ trace_event_buffer_commit(&fbuffer);
}

static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
@@ -343,9 +337,7 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
struct trace_event_file *trace_file;
struct syscall_trace_exit *entry;
struct syscall_metadata *sys_data;
- struct ring_buffer_event *event;
- struct trace_buffer *buffer;
- unsigned int trace_ctx;
+ struct trace_event_buffer fbuffer;
int syscall_nr;

syscall_nr = trace_get_syscall_nr(current, regs);
@@ -364,20 +356,15 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
if (!sys_data)
return;

- trace_ctx = tracing_gen_ctx();
-
- event = trace_event_buffer_lock_reserve(&buffer, trace_file,
- sys_data->exit_event->event.type, sizeof(*entry),
- trace_ctx);
- if (!event)
+ entry = trace_event_buffer_reserve(&fbuffer, trace_file, sizeof(*entry));
+ if (!entry)
return;

- entry = ring_buffer_event_data(event);
+ entry = ring_buffer_event_data(fbuffer.event);
entry->nr = syscall_nr;
entry->ret = syscall_get_return_value(current, regs);

- event_trigger_unlock_commit(trace_file, buffer, event, entry,
- trace_ctx);
+ trace_event_buffer_commit(&fbuffer);
}

static int reg_event_syscall_enter(struct trace_event_file *file,
--
2.35.1