Re: powerpc ftrace broken due to "manual merge of the ftrace tree with the arm64 tree"

[Steven Rostedt <rostedt@goodmis.org>]

On Fri, 15 Nov 2019 15:28:52 -0500
Qian Cai <cai@lca.pw> wrote:

> # echo function >/sys/kernel/debug/tracing/current_tracer
> 
> It hangs forever with today's linux-next on powerpc. Reverted the conflict fix
> [1] as below fixes the issue.
> 
> [1] https://lore.kernel.org/linux-next/20191115135357.10386fac@canb.auug.org.au/

What's your config file.

And can you test the two conflicting commits to see which one caused
your error?

Test this commit please: b83b43ffc6e4b514ca034a0fbdee01322e2f7022

And see if the issue is with that one, and not with the one without it.

-- Steve


> 
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-
> generic/vmlinux.lds.h
> index 7d0d03a03d4d..a92222f79b53 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -136,29 +136,20 @@
>  #endif
>  
>  #ifdef CONFIG_FTRACE_MCOUNT_RECORD
> -/*
> - * The ftrace call sites are logged to a section whose name depends on the
> - * compiler option used. A given kernel image will only use one, AKA
> - * FTRACE_CALLSITE_SECTION. We capture all of them here to avoid header
> - * dependencies for FTRACE_CALLSITE_SECTION's definition.
> - */
> -/*
> - * Need to also make ftrace_graph_stub point to ftrace_stub
> - * so that the same stub location may have different protocols
> - * and not mess up with C verifiers.
> - */
> -#define MCOUNT_REC()	. = ALIGN(8);				\
> +#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
> +#define MCOUNT_REC()	. = ALIGN(8)				\
>  			__start_mcount_loc = .;			\
> -			KEEP(*(__mcount_loc))			\
>  			KEEP(*(__patchable_function_entries))	\
>  			__stop_mcount_loc = .;			\
>  			ftrace_graph_stub = ftrace_stub;
>  #else
> -# ifdef CONFIG_FUNCTION_TRACER
> -#  define MCOUNT_REC()	ftrace_graph_stub = ftrace_stub;
> -# else
> -#  define MCOUNT_REC()
> -# endif
> +#define MCOUNT_REC()	. = ALIGN(8);				\
> +			__start_mcount_loc = .;			\
> +			KEEP(*(__mcount_loc))			\
> +			__stop_mcount_loc = .;
> +#endif
> +#else
> +#define MCOUNT_REC()
>  #endif
>  
>  #ifdef CONFIG_TRACE_BRANCH_PROFILING