Re: [PATCH v2 00/44] Meta Linux Kernel Port

From: Al Viro
Date: Wed Dec 05 2012 - 13:39:12 EST

On Wed, Dec 05, 2012 at 05:11:32PM +0000, Al Viro wrote:
> On Wed, Dec 05, 2012 at 04:08:18PM +0000, James Hogan wrote:
> > other work not included:
> > * switch to generic kernel_{thread,execve} (will be posted separately to
> > aid review)
> > other changes:
> ...
> > * switch to generic sys_execve
> ... which should've broken your kernel_execve().

BTW, one general note: lose the magical 7th argument. In the few syscalls
that do need pt_regs, you can bloody well use current_pt_regs() instead;
it's what, (register & constant) + constant? Passing it as explicit
argument is saving at most two arithmetical insns on those syscalls.
Moreover, for fork/clone/vfork we really don't need it until copy_thread();
one of the changes in -next kills passing pt_regs * to do_fork() and through
all that call chain (furthermore, if you make that
childregs->ctx.AX[0].U0 = ALIGN(usp, 8);
in copy_thread() conditional on usp != 0, you can go with generic
variants from kernel/fork.c; again, see linux-next for examples of that).
What's left? sigreturn and sigaltstack?

Seriously, drop that struct pt_regs *; it makes things uglier, (slightly)
hurts the syscall overhead and doesn't help the few syscalls that even
look at that argument.
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