[Devel] Re: [PATCH 2/2] clone_with_pids: define the s390 syscall

[Martin Schwidefsky]

Hi Serge,

On Mon, 15 Jun 2009 12:16:45 -0500
"Serge E. Hallyn" <serue at us.ibm.com> wrote:

> diff --git a/arch/s390/kernel/compat_wrapper.S b/arch/s390/kernel/compat_wrapper.S
> index c2228b2..bf13315 100644
> --- a/arch/s390/kernel/compat_wrapper.S
> +++ b/arch/s390/kernel/compat_wrapper.S
> @@ -1837,3 +1837,13 @@ sys_restore_wrapper:
>  	lgfr	%r3,%r3			# int
>  	llgfr	%r4,%r4			# unsigned long
>  	jg	compat_sys_restore
> +
> +	.globl sys_clone_with_pids_wrapper
> +sys_clone_with_pids_wrapper:
> +	llgfr	%r2,%r2			# unsigned long
> +	llgfr	%r3,%r3			# unsigned long
> +	llgtr	%r4,%r4			# int *
> +	llgtr	%r5,%r5			# int *
> +	llgtr	%r6,%r6			# void *
> +	llgtr	%r7,%r7			# void *
> +	jg	compat_sys_clone_with_pids

This is incorrect. If you have a system call that takes 6 parameters
you need to load/store the 6th parameter from the stack. Check out the
futex system call wrapper. But before you do that see the next comment.

> diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
> index a3acd8e..fa187bf 100644
> --- a/arch/s390/kernel/process.c
> +++ b/arch/s390/kernel/process.c
> @@ -246,6 +246,25 @@ SYSCALL_DEFINE0(clone)
>  		       parent_tidptr, child_tidptr);
>  }
> 
> +SYSCALL_DEFINE0(clone_with_pids)
> +{
> +	struct pt_regs *regs = task_pt_regs(current);
> +	unsigned long clone_flags;
> +	unsigned long newsp;
> +	int __user *parent_tidptr, *child_tidptr;
> +	void __user *upid_setp;
> +
> +	clone_flags = regs->gprs[3];
> +	newsp = regs->orig_gpr2;
> +	parent_tidptr = (int __user *) regs->gprs[4];
> +	child_tidptr = (int __user *) regs->gprs[5];
> +	upid_setp = (void __user *) regs->gprs[7];
> +	if (!newsp)
> +		newsp = regs->gprs[15];
> +	return do_fork_with_pids(clone_flags, newsp, regs, 0, parent_tidptr,
> +			child_tidptr, upid_setp);
> +}
> +
>  /*
>   * This is trivial, and on the face of it looks like it
>   * could equally well be done in user mode.

clone_with_pids is declared as system call with no paramters. In this
case the system call wrapper is not needed (empty) and you have to do
the compat conversion inside the system call. See sys32_clone.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

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