Re: [PATCH] make CALLER_ADDRx overwriteable

Ingo Molnar
2009-02-26T03:02:37Z

* Uwe Kleine-König <u.kleine-koenig@pengutronix.de> wrote:

> The current definition of CALLER_ADDRx isn't suitable for all platforms.
> E.g. for ARM __builtin_return_address(N) doesn't work for N > 0 and
> AFAIK for powerpc there are no frame pointers needed to have a working
> __builtin_return_address. This patch allows defining the CALLER_ADDRx
> macros in <asm/ftrace.h> and let these take precedence.
>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
> Hello,
>
> I think I don't break any architecture with this patch:
>
> $ for arch in $(ls arch/); do if test ! -d arch/$arch; then continue; fi; test -f arch/$arch/include/asm/ftrace.h || test -f include/asm-$arch/ftrace.h || { echo -n "$arch: "; git grep FTRACE arch/$arch | wc -l; } done
> alpha: 0
> avr32: 0
> blackfin: 0
> cris: 0
> frv: 0
> h8300: 0
> m32r: 0
> m68k: 0
> m68knommu: 0
> mips: 0
> mn10300: 0
> parisc: 0
> um: 0
> xtensa: 0
>
> So all archs that don't have <asm/ftrace.h> seem not to use FTRACE.
>
> Best regards
> Uwe
>
> include/linux/ftrace.h | 41 +++++++++++++++++++++--------------------
> 1 files changed, 21 insertions(+), 20 deletions(-)
>
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index 847bb3c..9d8d362 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -11,6 +11,8 @@
> #include <linux/bitops.h>
> #include <linux/sched.h>
>
> +#include <asm/ftrace.h>
> +
> #ifdef CONFIG_FUNCTION_TRACER
>
> extern int ftrace_enabled;
> @@ -103,8 +105,6 @@ struct ftrace_func_command {
> };
>
> #ifdef CONFIG_DYNAMIC_FTRACE
> -/* asm/ftrace.h must be defined for archs supporting dynamic ftrace */
> -#include <asm/ftrace.h>
>
> int ftrace_arch_code_modify_prepare(void);
> int ftrace_arch_code_modify_post_process(void);
> @@ -282,24 +282,25 @@ static inline void __ftrace_enabled_restore(int enabled)
> #endif
> }
>
> -#ifdef CONFIG_FRAME_POINTER
> -/* TODO: need to fix this for ARM */
> -# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
> -# define CALLER_ADDR1 ((unsigned long)__builtin_return_address(1))
> -# define CALLER_ADDR2 ((unsigned long)__builtin_return_address(2))
> -# define CALLER_ADDR3 ((unsigned long)__builtin_return_address(3))
> -# define CALLER_ADDR4 ((unsigned long)__builtin_return_address(4))
> -# define CALLER_ADDR5 ((unsigned long)__builtin_return_address(5))
> -# define CALLER_ADDR6 ((unsigned long)__builtin_return_address(6))
> -#else
> -# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
> -# define CALLER_ADDR1 0UL
> -# define CALLER_ADDR2 0UL
> -# define CALLER_ADDR3 0UL
> -# define CALLER_ADDR4 0UL
> -# define CALLER_ADDR5 0UL
> -# define CALLER_ADDR6 0UL
> -#endif
> +#ifndef CALLER_ADDR0
> +# ifdef CONFIG_FRAME_POINTER
> +# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
> +# define CALLER_ADDR1 ((unsigned long)__builtin_return_address(1))
> +# define CALLER_ADDR2 ((unsigned long)__builtin_return_address(2))
> +# define CALLER_ADDR3 ((unsigned long)__builtin_return_address(3))
> +# define CALLER_ADDR4 ((unsigned long)__builtin_return_address(4))
> +# define CALLER_ADDR5 ((unsigned long)__builtin_return_address(5))
> +# define CALLER_ADDR6 ((unsigned long)__builtin_return_address(6))
> +# else
> +# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
> +# define CALLER_ADDR1 0UL
> +# define CALLER_ADDR2 0UL
> +# define CALLER_ADDR3 0UL
> +# define CALLER_ADDR4 0UL
> +# define CALLER_ADDR5 0UL
> +# define CALLER_ADDR6 0UL
> +# endif
> +#endif /* ifndef CALLER_ADDR0 */

Makes sense!

Acked-by: Ingo Molnar <mingo@elte.hu>

Ingo