cond_syscall() and new ABI.

[Christoph Hellwig]

On Tue, Oct 12, 2004 at 02:51:49PM +0100, David Woodhouse wrote:
> This (in linux/asm-ppc64/unistd.h) doesn't work with the new ABI:
> 
> /*
>  * "Conditional" syscalls
>  *
>  * What we want is __attribute__((weak,alias("sys_ni_syscall"))),
>  * but it doesn't work on all toolchains, so we just do it by hand
>  */
> #define cond_syscall(x) asm(".weak\t." #x "\n\t.set\t." #x ",.sys_ni_syscall");
> 
> Two options -- either we ditch older toolchains (before 2002-03-01
> probably), by switching to what we say in the comment, or we introduce
> an ifdef to choose whether to include the '.' in the symbol names...
> 
> Both attached. Someone who cares can choose one :)
> 
> -- 
> dwmw2

> ===== include/asm-ppc64/unistd.h 1.34 vs edited =====
> --- 1.34/include/asm-ppc64/unistd.h	Tue Sep 14 01:23:12 2004
> +++ edited/include/asm-ppc64/unistd.h	Tue Oct 12 14:49:48 2004
> @@ -468,7 +468,11 @@
>   * What we want is __attribute__((weak,alias("sys_ni_syscall"))),
>   * but it doesn't work on all toolchains, so we just do it by hand
>   */
> +#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 3)
> +#define cond_syscall(x) asm(".weak\t" #x "\n\t.set\t" #x ",sys_ni_syscall");
> +#else
>  #define cond_syscall(x) asm(".weak\t." #x "\n\t.set\t." #x ",.sys_ni_syscall");

this is broken.  Gcc 3.4 doesn't even have support for the non-dotted
ABI, nevermind uses it by default.

> ===== include/asm-ppc64/unistd.h 1.34 vs edited =====
> --- 1.34/include/asm-ppc64/unistd.h	Tue Sep 14 01:23:12 2004
> +++ edited/include/asm-ppc64/unistd.h	Tue Oct 12 14:48:08 2004
> @@ -468,7 +468,7 @@
>   * What we want is __attribute__((weak,alias("sys_ni_syscall"))),
>   * but it doesn't work on all toolchains, so we just do it by hand
>   */
> -#define cond_syscall(x) asm(".weak\t." #x "\n\t.set\t." #x ",.sys_ni_syscall");
> +#define cond_syscall(x) void x(void) __attribute__((weak,alias("sys_ni_syscall")));


this one otoh makes lots of sense - it's what most architectures use.