Re: [PATCH] Add FUTEX_CMP_REQUEUE futex op

[Pete Zaitcev <zaitcev@redhat.com>]

On Mon, 7 Jun 2004 18:03:49 +0200
Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:

> --- linux-2.6/arch/s390/kernel/compat_wrapper.S	Mon Jun  7 16:07:24 2004
> +++ linux-2.6-s390/arch/s390/kernel/compat_wrapper.S	Mon Jun  7 16:07:53 2004
> @@ -1097,6 +1097,8 @@
>  	lgfr	%r4,%r4			# int
>  	llgtr	%r5,%r5			# struct compat_timespec *
>  	llgtr	%r6,%r6			# u32 *
> +	lgf	%r0,164(%r15)		# int
> +	stg	%r0,160(%r15)
>  	jg	compat_sys_futex	# branch to system call
>  
>  	.globl	sys32_setxattr_wrapper

Is it just me, or this could he above stand a use of STACK_FRAME_OVERHEAD
instead of 160? I envision a time when Ulrich Weigand comes out with
a gcc -fkernel, and at that time we'll need all such references
configurable.

> diff -urN linux-2.6/include/asm-s390/ptrace.h linux-2.6-s390/include/asm-s390/ptrace.h
> --- linux-2.6/include/asm-s390/ptrace.h	Mon May 10 04:32:54 2004
> +++ linux-2.6-s390/include/asm-s390/ptrace.h	Mon Jun  7 16:07:53 2004
> @@ -303,6 +303,7 @@
>   */
>  struct pt_regs 
>  {
> +	unsigned long args[1];
>  	psw_t psw;

This worries me, together with
   (__u32*)((addr_t) &__KSTK_PTREGS(child)->psw

Why not to place the necessary word outside of the struct?
It just logically doesn't belong. Might be just as easy to
do that mvc to other place.

I think I'll try to scope such an implemenation.

-- Pete