On Sat, Sep 22, 2012 at 09:16:11PM +1000, Greg Ungerer wrote: > I sent the patch to the m68k-linux list. Its been acked by Geert. > > http://marc.info/?l=linux-m68k&m=134742688015639&w=2 > > I was going to push it through the m68knommu git tree, but I don't mind > if you would rather take it with your changes. Applied. Other changes since the last update: * ppc breakage debugged and fixed * kernel_thread() unified on all converted architectures. An architecture can add select GENERIC_KERNEL_THREAD to its Kconfig if it's ready to handle that in its copy_thread() - regs will be NULL, usp - (unsigned long)fn, stck_size - (unsigned long)arg. It should set things up for ret_from_kernel_thread, so that the sucker would call given function on given argument. See what e.g. m68k does in #experimental-kernel_thread() in its copy_thread() and ret_from_kernel_thread; it's a fairly typical situation if you have enough callee-saved registers to play with. If not, put these values somewhere in childregs and pick them in ret_from_kernel_thread - see i386 for example of that. Eventually I hope to merge all kernel_thread() instances; then CONFIG_GENERIC_KERNEL_THREAD will be gone. Note, BTW, that having killed all in-kernel syscalls-via-trap on given architecture we get a chance to optimize the syscall glue; for instance, on ppc64 we could just go ahead and set stack pointer from %r13->kstack unconditionally, rather than playing with "if we are coming from the kernel mode, push stack pointer down by INT_FRAME_SIZE, otherwise pick it from per-CPU data structure pointed to by r13" as we do now. And that's just the most obvious bit in the very beginning of their system_call_common; there's more. I haven't touched that stuff - this kind of work belongs in architecture trees, not in this series. FWIW, if we do that conversion for all kernel_thread(), we get another nice thing pretty much for free - do_fork() won't need pt_regs passed to it anymore. Note that after that we have two possible values passed there - NULL (for kernel_thread()) and current_pt_regs() (from sys_fork() and friends). I.e. it's 1 bit of information, *and* we already have that bit - it's current->flags & PF_KTHREAD (it's actually a bit more convenient to check its copy in p->flags). Only kernel threads call kernel_thread(); only userland processes call sys_fork/sys_clone/sys_vfork(). IOW, all architectures are converted to generic kernel_thread() implementation, we can * stop passing pt_regs to do_fork() * stop passing pt_regs to copy_process() * stop passing pt_regs to copy_thread() - it can bloody well be calculated there. And it's not used until that point. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
