Re: Bug#609371: linux-image-2.6.37-trunk-sparc64: module scsi_mod: Unknown relocation: 36

[Steven Rostedt <rostedt@goodmis.org>]

On Tue, 2011-01-18 at 11:46 -0500, Mathieu Desnoyers wrote:
> * David Miller (davem@davemloft.net) wrote:
> > From: David Miller <davem@davemloft.net>
> > Date: Mon, 17 Jan 2011 22:00:39 -0800 (PST)
> > 
> > > ftrace: Remove unnecessary alignment tag from ftrace_event_call.
> > > 
> > > It's completely unnecessary and causes problems on platforms
> > > where this tag down-aligns the structure's alignment.
> > > 
> > > Signed-off-by: David S. Miller <davem@davemloft.net>
> >  ...
> > 
> > Ok, unless we can explain why these alignments are needed at all, we
> > should kill all of them:
> 
> ftrace: linker script add missing struct align
> 
> We should add the missing "STRUCT_ALIGN();" in
> include/asm-generic/vmlinux.lds.h as a preliminary step to remove the ftrace
> bogus structure alignments. Moving all STRUCT_ALIGN() for FTRACE_EVENTS()
> and TRACE_SYSCALLS() into the definitions, so the alignment is only done if
> these infrastructures are configured in. 
> 
> Also align TRACE_PRINTKS on 8 bytes to make sure the beginning of the section is
> aligned on pointer size.

If I can make it crash without the alignments and this fixes the issue,
I'll apply both patches.

Thanks,

-- Steve

> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> ---
>  include/asm-generic/vmlinux.lds.h |   19 ++++++++++---------
>  1 file changed, 10 insertions(+), 9 deletions(-)
> 
> Index: linux-2.6-lttng/include/asm-generic/vmlinux.lds.h
> ===================================================================
> --- linux-2.6-lttng.orig/include/asm-generic/vmlinux.lds.h
> +++ linux-2.6-lttng/include/asm-generic/vmlinux.lds.h
> @@ -107,7 +107,8 @@
>  #endif
>  
>  #ifdef CONFIG_TRACE_BRANCH_PROFILING
> -#define LIKELY_PROFILE()	VMLINUX_SYMBOL(__start_annotated_branch_profile) = .; \
> +#define LIKELY_PROFILE()	STRUCT_ALIGN();					      \
> +				VMLINUX_SYMBOL(__start_annotated_branch_profile) = .; \
>  				*(_ftrace_annotated_branch)			      \
>  				VMLINUX_SYMBOL(__stop_annotated_branch_profile) = .;
>  #else
> @@ -115,7 +116,8 @@
>  #endif
>  
>  #ifdef CONFIG_PROFILE_ALL_BRANCHES
> -#define BRANCH_PROFILE()	VMLINUX_SYMBOL(__start_branch_profile) = .;   \
> +#define BRANCH_PROFILE()	STRUCT_ALIGN();				      \
> +				VMLINUX_SYMBOL(__start_branch_profile) = .;   \
>  				*(_ftrace_branch)			      \
>  				VMLINUX_SYMBOL(__stop_branch_profile) = .;
>  #else
> @@ -123,7 +125,8 @@
>  #endif
>  
>  #ifdef CONFIG_EVENT_TRACING
> -#define FTRACE_EVENTS()	VMLINUX_SYMBOL(__start_ftrace_events) = .;	\
> +#define FTRACE_EVENTS()	STRUCT_ALIGN();					\
> +			VMLINUX_SYMBOL(__start_ftrace_events) = .;	\
>  			*(_ftrace_events)				\
>  			VMLINUX_SYMBOL(__stop_ftrace_events) = .;
>  #else
> @@ -131,7 +134,8 @@
>  #endif
>  
>  #ifdef CONFIG_TRACING
> -#define TRACE_PRINTKS() VMLINUX_SYMBOL(__start___trace_bprintk_fmt) = .;      \
> +#define TRACE_PRINTKS()  . = ALIGN(8);					       \
> +			 VMLINUX_SYMBOL(__start___trace_bprintk_fmt) = .;      \
>  			 *(__trace_printk_fmt) /* Trace_printk fmt' pointer */ \
>  			 VMLINUX_SYMBOL(__stop___trace_bprintk_fmt) = .;
>  #else
> @@ -139,7 +143,8 @@
>  #endif
>  
>  #ifdef CONFIG_FTRACE_SYSCALLS
> -#define TRACE_SYSCALLS() VMLINUX_SYMBOL(__start_syscalls_metadata) = .;	\
> +#define TRACE_SYSCALLS() STRUCT_ALIGN();				\
> +			 VMLINUX_SYMBOL(__start_syscalls_metadata) = .;	\
>  			 *(__syscalls_metadata)				\
>  			 VMLINUX_SYMBOL(__stop_syscalls_metadata) = .;
>  #else
> @@ -169,11 +174,7 @@
>  	LIKELY_PROFILE()		       				\
>  	BRANCH_PROFILE()						\
>  	TRACE_PRINTKS()							\
> -									\
> -	STRUCT_ALIGN();							\
>  	FTRACE_EVENTS()							\
> -									\
> -	STRUCT_ALIGN();							\
>  	TRACE_SYSCALLS()
>  
>  /*
> 
> 
>