Re: [PATCH 02/14] x86: add arch_compat_syscall_addr()

[Frederic Weisbecker <fweisbec@gmail.com>]

On Tue, Mar 16, 2010 at 01:46:17PM -0400, Jason Baron wrote:
> Add arch_compat_syscall_addr(int nr) for x86_64. This is in preparation for adding
> compat syscall support to the event tracer.
> 
> Signed-off-by: Jason Baron <jbaron@redhat.com>
> ---
>  arch/x86/include/asm/syscall.h |    5 +++++
>  arch/x86/kernel/ftrace.c       |    8 ++++++++
>  2 files changed, 13 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
> index c4a348f..4e462cc 100644
> --- a/arch/x86/include/asm/syscall.h
> +++ b/arch/x86/include/asm/syscall.h
> @@ -16,7 +16,12 @@
>  #include <linux/sched.h>
>  #include <linux/err.h>
>  
> +#if defined(CONFIG_COMPAT) && defined(CONFIG_FTRACE_SYSCALLS)
> + #define __HAVE_ARCH_FTRACE_COMPAT_SYSCALLS
> +#endif
> +



A config would be better:

arch/Kconfig:

	config HAVE_COMPAT_FTRACE_SYSCALLS
		bool

	config COMPAT_FTRACE_SYSCALLS
		def_bool y
		depends on COMPAT && FTRACE_SYSCALLS && HAVE_COMPAT_FTRACE_SYSCALLS

arch/x86/Kconfig:

	config X86
		[...]
		select HAVE_COMPAT_FTRACE_SYSCALLS
		[...]

So that we centralize the definition of COMPAT_FTRACE_SYSCALLS and
we don't need every archs to redefine the dependency and to stay sync
with potential dependency changes.

Thanks.



>  extern const unsigned long sys_call_table[];
> +extern const unsigned long *ia32_sys_call_table;
>  
>  /*
>   * Only the low 32 bits of orig_ax are meaningful, so we return int.
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index cd37469..4b36a0b 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -26,6 +26,7 @@
>  #include <asm/ftrace.h>
>  #include <asm/nops.h>
>  #include <asm/nmi.h>
> +#include <asm/syscall.h>
>  
>  
>  #ifdef CONFIG_DYNAMIC_FTRACE
> @@ -510,3 +511,10 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
>  	}
>  }
>  #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> +
> +#ifdef __HAVE_ARCH_FTRACE_COMPAT_SYSCALLS
> +unsigned long __init arch_compat_syscall_addr(int nr)
> +{
> +	return (unsigned long)(&ia32_sys_call_table)[nr];
> +}
> +#endif
> -- 
> 1.6.5.1
>