Commit d08e4113 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt (VMware)
Browse files

tracing/syscalls: Pass in hardcoded 6 into syscall_get_arguments() 

The only users that calls syscall_get_arguments() with a variable and not a
hard coded '6' is ftrace_syscall_enter(). syscall_get_arguments() can be
optimized by removing a variable input, and always grabbing 6 arguments
regardless of what the system call actually uses.

Change ftrace_syscall_enter() to pass the 6 args into a local stack array
and copy the necessary arguments into the trace event as needed.

This is needed to remove two parameters from syscall_get_arguments().

Link: http://lkml.kernel.org/r/20161107213233.627583542@goodmis.org



Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 631b7aba

kernel/trace/trace_syscalls.c

+6 −3
Original line number Diff line number Diff line
@@ -314,6 +314,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id) 
	struct ring_buffer_event *event;

	struct ring_buffer *buffer;

	unsigned long irq_flags;

	unsigned long args[6];

	int pc;

	int syscall_nr;

	int size;
@@ -347,7 +348,8 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id) 


	entry = ring_buffer_event_data(event);

	entry->nr = syscall_nr;

	syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);

	syscall_get_arguments(current, regs, 0, 6, args);

	memcpy(entry->args, args, sizeof(unsigned long) * sys_data->nb_args);



	event_trigger_unlock_commit(trace_file, buffer, event, entry,

				    irq_flags, pc);
@@ -583,6 +585,7 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id) 
	struct syscall_metadata *sys_data;

	struct syscall_trace_enter *rec;

	struct hlist_head *head;

	unsigned long args[6];

	bool valid_prog_array;

	int syscall_nr;

	int rctx;
@@ -613,8 +616,8 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id) 
		return;



	rec->nr = syscall_nr;

	syscall_get_arguments(current, regs, 0, sys_data->nb_args,

			       (unsigned long *)&rec->args);

	syscall_get_arguments(current, regs, 0, 6, args);

	memcpy(&rec->args, args, sizeof(unsigned long) * sys_data->nb_args);



	if ((valid_prog_array &&

	     !perf_call_bpf_enter(sys_data->enter_event, regs, sys_data, rec)) ||

CRA Git | Maintained and supported by SUSTech CRA and CCSE