Commit e49dc19c authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

ftrace: function graph return for function entry 



Impact: feature, let entry function decide to trace or not

This patch lets the graph tracer entry function decide if the tracing
should be done at the end as well. This requires all function graph
entry functions return 1 if it should trace, or 0 if the return should
not be traced.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7ee991fb

arch/x86/kernel/entry_32.S

+3 −0
Original line number Diff line number Diff line
@@ -1196,6 +1196,9 @@ ENTRY(mcount) 
#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	cmpl $ftrace_stub, ftrace_graph_return

	jnz ftrace_graph_caller



	cmpl $ftrace_graph_entry_stub, ftrace_graph_entry

	jnz ftrace_graph_caller

#endif

.globl ftrace_stub

ftrace_stub:

arch/x86/kernel/entry_64.S

+3 −0
Original line number Diff line number Diff line
@@ -120,6 +120,9 @@ ENTRY(mcount) 
#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	cmpq $ftrace_stub, ftrace_graph_return

	jnz ftrace_graph_caller



	cmpq $ftrace_graph_entry_stub, ftrace_graph_entry

	jnz ftrace_graph_caller

#endif



.globl ftrace_stub

arch/x86/kernel/ftrace.c

+6 −1
Original line number Diff line number Diff line
@@ -425,6 +425,7 @@ static void pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret) 
	trace->calltime = current->ret_stack[index].calltime;

	trace->overrun = atomic_read(&current->trace_overrun);

	trace->depth = index;

	barrier();

	current->curr_ret_stack--;

}
@@ -506,7 +507,11 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) 
	}



	trace.func = self_addr;

	ftrace_graph_entry(&trace);



	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace)) {

		current->curr_ret_stack--;

		*parent = old;

	}

}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

include/linux/ftrace.h

+1 −1
Original line number Diff line number Diff line
@@ -371,7 +371,7 @@ struct ftrace_graph_ret { 
#define FTRACE_RETSTACK_ALLOC_SIZE 32

/* Type of the callback handlers for tracing function graph*/

typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *); /* return */

typedef void (*trace_func_graph_ent_t)(struct ftrace_graph_ent *); /* entry */

typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *); /* entry */



extern int register_ftrace_graph(trace_func_graph_ret_t retfunc,

				trace_func_graph_ent_t entryfunc);

kernel/trace/ftrace.c

+7 −3
Original line number Diff line number Diff line
@@ -1636,11 +1636,15 @@ ftrace_enable_sysctl(struct ctl_table *table, int write, 


static atomic_t ftrace_graph_active;



int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)

{

	return 0;

}



/* The callbacks that hook a function */

trace_func_graph_ret_t ftrace_graph_return =

			(trace_func_graph_ret_t)ftrace_stub;

trace_func_graph_ent_t ftrace_graph_entry =

			(trace_func_graph_ent_t)ftrace_stub;

trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;



/* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */

static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
@@ -1738,7 +1742,7 @@ void unregister_ftrace_graph(void) 


	atomic_dec(&ftrace_graph_active);

	ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;

	ftrace_graph_entry = (trace_func_graph_ent_t)ftrace_stub;

	ftrace_graph_entry = ftrace_graph_entry_stub;

	ftrace_shutdown(FTRACE_STOP_FUNC_RET);



	mutex_unlock(&ftrace_sysctl_lock);

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