Re: system gets stuck in a lock during boot

[Steven Rostedt]

On Fri, 2009-10-02 at 17:12 -0400, Jason Baron wrote:

> hi Justin,
> 
> I've been playing around with gcc '4.5' as well and hit a panic that
> looks very similar to what you've seen with stock 2.6.31 - I haven't
> seen it anywhere else. Anyways, it seems to be some sort of alignment
> issue with the 'struct ftrace_event_call'. I'm not sure yet if this is a
> compiler or kernel issue. But the following kernel patch fixes the issue
> for me. It would be interesting to verify if the patch also resolves the
> issue for you.
> 
> thanks,
> 
> -Jason
> 
> 
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 6ad76bf..0029af4 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -164,6 +164,7 @@
>  	LIKELY_PROFILE()		       				\
>  	BRANCH_PROFILE()						\
>  	TRACE_PRINTKS()							\
> +	. = ALIGN(32);							\
>  	FTRACE_EVENTS()							\
>  	TRACE_SYSCALLS()
>  
> diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
> index a81170d..43f9f1e 100644
> --- a/include/linux/ftrace_event.h
> +++ b/include/linux/ftrace_event.h
> @@ -124,7 +124,7 @@ struct ftrace_event_call {
>  	atomic_t		profile_count;
>  	int			(*profile_enable)(struct ftrace_event_call *);
>  	void			(*profile_disable)(struct ftrace_event_call *);
> -};
> +} __attribute__((aligned(32)));
>  
>  #define MAX_FILTER_PRED		32
>  #define MAX_FILTER_STR_VAL	128
> diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
> index f64fbaa..4697fb6 100644
> --- a/include/trace/ftrace.h
> +++ b/include/trace/ftrace.h
> @@ -600,7 +600,7 @@ static int ftrace_raw_init_event_##call(void)				\
>  }									\
>  									\
>  static struct ftrace_event_call __used					\
> -__attribute__((__aligned__(4)))						\
> +__attribute__((__aligned__(32)))					\
>  __attribute__((section("_ftrace_events"))) event_##call = {		\
>  	.name			= #call,				\
>  	.system			= __stringify(TRACE_SYSTEM),		\

Are all alignments needed? Or just adding one might help. Or removing
the one directly above?

-- Steve


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