Re: mm: new mm hook framework

From: Geert Uytterhoeven
Date: Thu Jun 25 2015 - 03:12:53 EST

On Thu, Jun 25, 2015 at 6:08 AM, Linux Kernel Mailing List
<linux-kernel@xxxxxxxxxxxxxxx> wrote:
> Gitweb: http://git.kernel.org/linus/;a=commit;h=2ae416b142b625c58c9ccb039aa3ef48ad0e9bae
> Commit: 2ae416b142b625c58c9ccb039aa3ef48ad0e9bae
> Parent: e81f2d22370f8231cb7f13f454bcc8c0eb4e23f2
> Refname: refs/heads/master
> Author: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx>
> AuthorDate: Wed Jun 24 16:56:16 2015 -0700
> Committer: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> CommitDate: Wed Jun 24 17:49:41 2015 -0700
>
> mm: new mm hook framework
>
> CRIU is recreating the process memory layout by remapping the checkpointee
> memory area on top of the current process (criu). This includes remapping
> the vDSO to the place it has at checkpoint time.
>
> However some architectures like powerpc are keeping a reference to the
> vDSO base address to build the signal return stack frame by calling the
> vDSO sigreturn service. So once the vDSO has been moved, this reference
> is no more valid and the signal frame built later are not usable.
>
> This patch serie is introducing a new mm hook framework, and a new
> arch_remap hook which is called when mremap is done and the mm lock still
> hold. The next patch is adding the vDSO remap and unmap tracking to the
> powerpc architecture.
>
> This patch (of 3):
>
> This patch introduces a new set of header file to manage mm hooks:
> - per architecture empty header file (arch/x/include/asm/mm-arch-hooks.h)
> - a generic header (include/linux/mm-arch-hooks.h)
>
> The architecture which need to overwrite a hook as to redefine it in its
> header file, while architecture which doesn't need have nothing to do.
>
> The default hooks are defined in the generic header and are used in the
> case the architecture is not defining it.
>
> In a next step, mm hooks defined in include/asm-generic/mm_hooks.h should
> be moved here.
>
> Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx>
> Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> Cc: Paul Mackerras <paulus@xxxxxxxxx>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> ---
> arch/alpha/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/arc/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/arm/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/arm64/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/avr32/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/blackfin/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/c6x/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/cris/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/frv/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/hexagon/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/ia64/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/m32r/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/m68k/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/metag/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/microblaze/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/mips/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/mn10300/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/nios2/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/openrisc/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/parisc/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/powerpc/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/s390/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/score/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/sh/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/sparc/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/tile/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/um/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/unicore32/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/x86/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> arch/xtensa/include/asm/mm-arch-hooks.h | 15 +++++++++++++++
> include/linux/mm-arch-hooks.h | 16 ++++++++++++++++

Touching all arch/ directories without a CC to linux-arch?

> 31 files changed, 466 insertions(+)
>
> diff --git a/arch/alpha/include/asm/mm-arch-hooks.h b/arch/alpha/include/asm/mm-arch-hooks.h
> new file mode 100644
> index 0000000..b07fd86
> --- /dev/null
> +++ b/arch/alpha/include/asm/mm-arch-hooks.h
> @@ -0,0 +1,15 @@
> +/*
> + * Architecture specific mm hooks
> + *
> + * Copyright (C) 2015, IBM Corporation
> + * Author: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx>

Cool, copyright on an empty header!

> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#ifndef _ASM_ALPHA_MM_ARCH_HOOKS_H
> +#define _ASM_ALPHA_MM_ARCH_HOOKS_H
> +
> +#endif /* _ASM_ALPHA_MM_ARCH_HOOKS_H */

[...]

IMHO this screams for the generic version in include/asm-generic/,
and "generic-y += mm-arch-hooks.h" in arch/*/include/asm/Kbuild/.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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