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Date:   Thu, 22 Nov 2018 19:13:38 -0800
From:   Joel Fernandes <joel@joelfernandes.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>
Subject: Re: [RFC][PATCH 09/14] function_graph: Move ftrace_graph_get_addr()
 to fgraph.c
Message-ID: <20181123031338.GC17060@google.com>
References: <20181122012708.491151844@goodmis.org>
 <20181122012803.843285508@goodmis.org>
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On Wed, Nov 21, 2018 at 08:27:17PM -0500, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
> 
> Move the function function_graph_get_addr() to fgraph.c, as the management
> of the curr_ret_stack is going to change, and all the accesses to ret_stack
> needs to be done in fgraph.c.

s/ftrace_graph_get_addr/ftrace_graph_ret_addr/

thanks,

 - Joel

> 
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> ---
>  kernel/trace/fgraph.c                | 55 ++++++++++++++++++++++++++++
>  kernel/trace/trace_functions_graph.c | 55 ----------------------------
>  2 files changed, 55 insertions(+), 55 deletions(-)
> 
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index f3a89ecac671..c7d612897e33 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -233,6 +233,61 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
>  	return ret;
>  }
>  
> +/**
> + * ftrace_graph_ret_addr - convert a potentially modified stack return address
> + *			   to its original value
> + *
> + * This function can be called by stack unwinding code to convert a found stack
> + * return address ('ret') to its original value, in case the function graph
> + * tracer has modified it to be 'return_to_handler'.  If the address hasn't
> + * been modified, the unchanged value of 'ret' is returned.
> + *
> + * 'idx' is a state variable which should be initialized by the caller to zero
> + * before the first call.
> + *
> + * 'retp' is a pointer to the return address on the stack.  It's ignored if
> + * the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined.
> + */
> +#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
> +unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
> +				    unsigned long ret, unsigned long *retp)
> +{
> +	int index = task->curr_ret_stack;
> +	int i;
> +
> +	if (ret != (unsigned long)return_to_handler)
> +		return ret;
> +
> +	if (index < 0)
> +		return ret;
> +
> +	for (i = 0; i <= index; i++)
> +		if (task->ret_stack[i].retp == retp)
> +			return task->ret_stack[i].ret;
> +
> +	return ret;
> +}
> +#else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
> +unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
> +				    unsigned long ret, unsigned long *retp)
> +{
> +	int task_idx;
> +
> +	if (ret != (unsigned long)return_to_handler)
> +		return ret;
> +
> +	task_idx = task->curr_ret_stack;
> +
> +	if (!task->ret_stack || task_idx < *idx)
> +		return ret;
> +
> +	task_idx -= *idx;
> +	(*idx)++;
> +
> +	return task->ret_stack[task_idx].ret;
> +}
> +#endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
> +
>  static struct ftrace_ops graph_ops = {
>  	.func			= ftrace_stub,
>  	.flags			= FTRACE_OPS_FL_RECURSION_SAFE |
> diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> index 7c7fd13d2373..0f9cbc30645d 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c
> @@ -90,61 +90,6 @@ static void
>  print_graph_duration(struct trace_array *tr, unsigned long long duration,
>  		     struct trace_seq *s, u32 flags);
>  
> -/**
> - * ftrace_graph_ret_addr - convert a potentially modified stack return address
> - *			   to its original value
> - *
> - * This function can be called by stack unwinding code to convert a found stack
> - * return address ('ret') to its original value, in case the function graph
> - * tracer has modified it to be 'return_to_handler'.  If the address hasn't
> - * been modified, the unchanged value of 'ret' is returned.
> - *
> - * 'idx' is a state variable which should be initialized by the caller to zero
> - * before the first call.
> - *
> - * 'retp' is a pointer to the return address on the stack.  It's ignored if
> - * the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined.
> - */
> -#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
> -unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
> -				    unsigned long ret, unsigned long *retp)
> -{
> -	int index = task->curr_ret_stack;
> -	int i;
> -
> -	if (ret != (unsigned long)return_to_handler)
> -		return ret;
> -
> -	if (index < 0)
> -		return ret;
> -
> -	for (i = 0; i <= index; i++)
> -		if (task->ret_stack[i].retp == retp)
> -			return task->ret_stack[i].ret;
> -
> -	return ret;
> -}
> -#else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
> -unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
> -				    unsigned long ret, unsigned long *retp)
> -{
> -	int task_idx;
> -
> -	if (ret != (unsigned long)return_to_handler)
> -		return ret;
> -
> -	task_idx = task->curr_ret_stack;
> -
> -	if (!task->ret_stack || task_idx < *idx)
> -		return ret;
> -
> -	task_idx -= *idx;
> -	(*idx)++;
> -
> -	return task->ret_stack[task_idx].ret;
> -}
> -#endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
> -
>  int __trace_graph_entry(struct trace_array *tr,
>  				struct ftrace_graph_ent *trace,
>  				unsigned long flags,
> -- 
> 2.19.1
> 
>