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SubjectRe: [PATCH 05/19] x86/dumpstack: fix function graph tracing stack dump reliability issues
On Tue, 2 Aug 2016 21:50:12 -0500
Josh Poimboeuf <jpoimboe@redhat.com> wrote:


> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index 1e814ae..fc508a7 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -795,7 +795,9 @@ struct ftrace_ret_stack {
> unsigned long func;
> unsigned long long calltime;
> unsigned long long subtime;
> +#if defined(CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST) && !defined(CC_USING_FENTRY)

We need to make a new defined in ftrace.h:

#if defined(CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST) && !defined(CC_USING_FENTRY)
# define HAVE_FUNCTION_GRAPH_FP_TEST
#endif

And use that instead of this && complexity.

Or better yet, get rid of the CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST define
and only have HAVE_FUNCTION_GRAPH_FP_TEST defined in the asm/ftrace.h
in each arch. Then, x86 could just do;

#ifndef CC_USING_FENTRY
# define HAVE_FUNCTION_GRAPH_FP_TEST
#endif


-- Steve

> unsigned long fp;
> +#endif
> };
>
> /*
> diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> index 9caa9b2..86b2719 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c
> @@ -171,7 +171,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
> current->ret_stack[index].func = func;
> current->ret_stack[index].calltime = calltime;
> current->ret_stack[index].subtime = 0;
> +#if defined(CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST) && !defined(CC_USING_FENTRY)
> current->ret_stack[index].fp = frame_pointer;
> +#endif
> *depth = current->curr_ret_stack;
>
> return 0;

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