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

[Qian Cai]

On Mon, 2019-11-18 at 10:16 -0500, Steven Rostedt wrote:
> On Mon, 18 Nov 2019 09:58:42 -0500
> Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> 
> > On Mon, 18 Nov 2019 09:51:04 -0500
> > Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> > 
> > > > > Test this commit please: b83b43ffc6e4b514ca034a0fbdee01322e2f7022      
> > > > 
> > > > # git reset --hard b83b43ffc6e4b514ca034a0fbdee01322e2f7022
> > > > 
> > > > Yes, that one is bad.    
> > > 
> > > Can you see if this patch fixes the issue for you?  
> > 
> > Don't bother. This isn't the right fix, I know see the real issue.
> > 
> > New fix coming shortly.
> > 
> 
> Can you try this?

Yes, it works fine.

> 
> It appears that I picked a name "ftrace_graph_stub", that was already in
> use by powerpc. This just renames the function stub I used.
> 
> -- Steve
> 
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 0f358be551cd..996db32c491b 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -112,7 +112,7 @@
>  #ifdef CONFIG_FTRACE_MCOUNT_RECORD
>  #ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
>  /*
> - * Need to also make ftrace_graph_stub point to ftrace_stub
> + * Need to also make ftrace_stub_graph point to ftrace_stub
>   * so that the same stub location may have different protocols
>   * and not mess up with C verifiers.
>   */
> @@ -120,17 +120,17 @@
>  			__start_mcount_loc = .;			\
>  			KEEP(*(__patchable_function_entries))	\
>  			__stop_mcount_loc = .;			\
> -			ftrace_graph_stub = ftrace_stub;
> +			ftrace_stub_graph = ftrace_stub;
>  #else
>  #define MCOUNT_REC()	. = ALIGN(8);				\
>  			__start_mcount_loc = .;			\
>  			KEEP(*(__mcount_loc))			\
>  			__stop_mcount_loc = .;			\
> -			ftrace_graph_stub = ftrace_stub;
> +			ftrace_stub_graph = ftrace_stub;
>  #endif
>  #else
>  # ifdef CONFIG_FUNCTION_TRACER
> -#  define MCOUNT_REC()	ftrace_graph_stub = ftrace_stub;
> +#  define MCOUNT_REC()	ftrace_stub_graph = ftrace_stub;
>  # else
>  #  define MCOUNT_REC()
>  # endif
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index fa3ce10d0405..67e0c462b059 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -336,10 +336,10 @@ int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
>   * Simply points to ftrace_stub, but with the proper protocol.
>   * Defined by the linker script in linux/vmlinux.lds.h
>   */
> -extern void ftrace_graph_stub(struct ftrace_graph_ret *);
> +extern void ftrace_stub_graph(struct ftrace_graph_ret *);
>  
>  /* The callbacks that hook a function */
> -trace_func_graph_ret_t ftrace_graph_return = ftrace_graph_stub;
> +trace_func_graph_ret_t ftrace_graph_return = ftrace_stub_graph;
>  trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
>  static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub;
>  
> @@ -619,7 +619,7 @@ void unregister_ftrace_graph(struct fgraph_ops *gops)
>  		goto out;
>  
>  	ftrace_graph_active--;
> -	ftrace_graph_return = ftrace_graph_stub;
> +	ftrace_graph_return = ftrace_stub_graph;
>  	ftrace_graph_entry = ftrace_graph_entry_stub;
>  	__ftrace_graph_entry = ftrace_graph_entry_stub;
>  	ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);