Re: [PATCH 1/7] tracing/function-graph-tracer: make arch genericpush pop functions

[Steven Rostedt]

Ingo,

This patch is to make function graph arch generic. But since the PowerPC 
changes depend on it, we want to push it through the PowerPC tree. But 
since it touches x86 code, can you give an Acked-by to it?

Thanks,

-- Steve


On Fri, 13 Feb 2009, Steven Rostedt wrote:

> From: Steven Rostedt <srostedt@xxxxxxxxxx>
> 
> There is nothing really arch specific of the push and pop functions
> used by the function graph tracer. This patch moves them to generic
> code.
> 
> Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> Signed-off-by: Steven Rostedt <srostedt@xxxxxxxxxx>
> ---
>  arch/x86/include/asm/ftrace.h        |   25 -----------
>  arch/x86/kernel/ftrace.c             |   75 +---------------------------------
>  include/linux/ftrace.h               |   24 +++++++++++
>  kernel/trace/trace_functions_graph.c |   75 ++++++++++++++++++++++++++++++++++
>  4 files changed, 100 insertions(+), 99 deletions(-)
> 
> diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
> index b55b4a7..db24c22 100644
> --- a/arch/x86/include/asm/ftrace.h
> +++ b/arch/x86/include/asm/ftrace.h
> @@ -55,29 +55,4 @@ struct dyn_arch_ftrace {
>  #endif /* __ASSEMBLY__ */
>  #endif /* CONFIG_FUNCTION_TRACER */
>  
> -#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> -
> -#ifndef __ASSEMBLY__
> -
> -/*
> - * Stack of return addresses for functions
> - * of a thread.
> - * Used in struct thread_info
> - */
> -struct ftrace_ret_stack {
> -	unsigned long ret;
> -	unsigned long func;
> -	unsigned long long calltime;
> -};
> -
> -/*
> - * Primary handler of a function return.
> - * It relays on ftrace_return_to_handler.
> - * Defined in entry_32/64.S
> - */
> -extern void return_to_handler(void);
> -
> -#endif /* __ASSEMBLY__ */
> -#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> -
>  #endif /* _ASM_X86_FTRACE_H */
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index 1b43086..258c8d5 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -389,79 +389,6 @@ void ftrace_nmi_exit(void)
>  
>  #endif /* !CONFIG_DYNAMIC_FTRACE */
>  
> -/* Add a function return address to the trace stack on thread info.*/
> -static int push_return_trace(unsigned long ret, unsigned long long time,
> -				unsigned long func, int *depth)
> -{
> -	int index;
> -
> -	if (!current->ret_stack)
> -		return -EBUSY;
> -
> -	/* The return trace stack is full */
> -	if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
> -		atomic_inc(&current->trace_overrun);
> -		return -EBUSY;
> -	}
> -
> -	index = ++current->curr_ret_stack;
> -	barrier();
> -	current->ret_stack[index].ret = ret;
> -	current->ret_stack[index].func = func;
> -	current->ret_stack[index].calltime = time;
> -	*depth = index;
> -
> -	return 0;
> -}
> -
> -/* Retrieve a function return address to the trace stack on thread info.*/
> -static void pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
> -{
> -	int index;
> -
> -	index = current->curr_ret_stack;
> -
> -	if (unlikely(index < 0)) {
> -		ftrace_graph_stop();
> -		WARN_ON(1);
> -		/* Might as well panic, otherwise we have no where to go */
> -		*ret = (unsigned long)panic;
> -		return;
> -	}
> -
> -	*ret = current->ret_stack[index].ret;
> -	trace->func = current->ret_stack[index].func;
> -	trace->calltime = current->ret_stack[index].calltime;
> -	trace->overrun = atomic_read(&current->trace_overrun);
> -	trace->depth = index;
> -	barrier();
> -	current->curr_ret_stack--;
> -
> -}
> -
> -/*
> - * Send the trace to the ring-buffer.
> - * @return the original return address.
> - */
> -unsigned long ftrace_return_to_handler(void)
> -{
> -	struct ftrace_graph_ret trace;
> -	unsigned long ret;
> -
> -	pop_return_trace(&trace, &ret);
> -	trace.rettime = cpu_clock(raw_smp_processor_id());
> -	ftrace_graph_return(&trace);
> -
> -	if (unlikely(!ret)) {
> -		ftrace_graph_stop();
> -		WARN_ON(1);
> -		/* Might as well panic. What else to do? */
> -		ret = (unsigned long)panic;
> -	}
> -
> -	return ret;
> -}
> -
>  /*
>   * Hook the return address and push it in the stack of return addrs
>   * in current thread info.
> @@ -520,7 +447,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
>  
>  	calltime = cpu_clock(raw_smp_processor_id());
>  
> -	if (push_return_trace(old, calltime,
> +	if (ftrace_push_return_trace(old, calltime,
>  				self_addr, &trace.depth) == -EBUSY) {
>  		*parent = old;
>  		return;
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index 677432b..a7f8134 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -380,6 +380,30 @@ struct ftrace_graph_ret {
>  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
>  
>  /*
> + * Stack of return addresses for functions
> + * of a thread.
> + * Used in struct thread_info
> + */
> +struct ftrace_ret_stack {
> +	unsigned long ret;
> +	unsigned long func;
> +	unsigned long long calltime;
> +};
> +
> +/*
> + * Primary handler of a function return.
> + * It relays on ftrace_return_to_handler.
> + * Defined in entry_32/64.S
> + */
> +extern void return_to_handler(void);
> +
> +extern int
> +ftrace_push_return_trace(unsigned long ret, unsigned long long time,
> +			 unsigned long func, int *depth);
> +extern void
> +ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret);
> +
> +/*
>   * Sometimes we don't want to trace a function with the function
>   * graph tracer but we want them to keep traced by the usual function
>   * tracer if the function graph tracer is not configured.
> diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> index 930c08e..dce71a5 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c
> @@ -42,6 +42,81 @@ static struct tracer_flags tracer_flags = {
>  /* pid on the last trace processed */
>  static pid_t last_pid[NR_CPUS] = { [0 ... NR_CPUS-1] = -1 };
>  
> +/* Add a function return address to the trace stack on thread info.*/
> +int
> +ftrace_push_return_trace(unsigned long ret, unsigned long long time,
> +			 unsigned long func, int *depth)
> +{
> +	int index;
> +
> +	if (!current->ret_stack)
> +		return -EBUSY;
> +
> +	/* The return trace stack is full */
> +	if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
> +		atomic_inc(&current->trace_overrun);
> +		return -EBUSY;
> +	}
> +
> +	index = ++current->curr_ret_stack;
> +	barrier();
> +	current->ret_stack[index].ret = ret;
> +	current->ret_stack[index].func = func;
> +	current->ret_stack[index].calltime = time;
> +	*depth = index;
> +
> +	return 0;
> +}
> +
> +/* Retrieve a function return address to the trace stack on thread info.*/
> +void
> +ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
> +{
> +	int index;
> +
> +	index = current->curr_ret_stack;
> +
> +	if (unlikely(index < 0)) {
> +		ftrace_graph_stop();
> +		WARN_ON(1);
> +		/* Might as well panic, otherwise we have no where to go */
> +		*ret = (unsigned long)panic;
> +		return;
> +	}
> +
> +	*ret = current->ret_stack[index].ret;
> +	trace->func = current->ret_stack[index].func;
> +	trace->calltime = current->ret_stack[index].calltime;
> +	trace->overrun = atomic_read(&current->trace_overrun);
> +	trace->depth = index;
> +	barrier();
> +	current->curr_ret_stack--;
> +
> +}
> +
> +/*
> + * Send the trace to the ring-buffer.
> + * @return the original return address.
> + */
> +unsigned long ftrace_return_to_handler(void)
> +{
> +	struct ftrace_graph_ret trace;
> +	unsigned long ret;
> +
> +	ftrace_pop_return_trace(&trace, &ret);
> +	trace.rettime = cpu_clock(raw_smp_processor_id());
> +	ftrace_graph_return(&trace);
> +
> +	if (unlikely(!ret)) {
> +		ftrace_graph_stop();
> +		WARN_ON(1);
> +		/* Might as well panic. What else to do? */
> +		ret = (unsigned long)panic;
> +	}
> +
> +	return ret;
> +}
> +
>  static int graph_trace_init(struct trace_array *tr)
>  {
>  	int cpu, ret;
> -- 
> 1.5.6.5
> 
> -- 
> 
> 
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