linux-kernel - Re: [PATCH mm v4 00/39] kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW

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Date:   Thu, 30 Dec 2021 20:11:46 +0100
From:   Andrey Konovalov <andreyknvl@...il.com>
To:     Marco Elver <elver@...gle.com>
Cc:     andrey.konovalov@...ux.dev,
        Alexander Potapenko <glider@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: Re: [PATCH mm v4 00/39] kasan, vmalloc, arm64: add vmalloc tagging
 support for SW/HW_TAGS

On Wed, Dec 22, 2021 at 8:01 AM Marco Elver <elver@...gle.com> wrote:
>
> On Mon, 20 Dec 2021 at 22:58, <andrey.konovalov@...ux.dev> wrote:
> >
> > From: Andrey Konovalov <andreyknvl@...gle.com>
> >
> > Hi,
> >
> > This patchset adds vmalloc tagging support for SW_TAGS and HW_TAGS
> > KASAN modes.
> >
> > The tree with patches is available here:
> >
> > https://github.com/xairy/linux/tree/up-kasan-vmalloc-tags-v4-akpm
> >
> > About half of patches are cleanups I went for along the way. None of
> > them seem to be important enough to go through stable, so I decided
> > not to split them out into separate patches/series.
> >
> > The patchset is partially based on an early version of the HW_TAGS
> > patchset by Vincenzo that had vmalloc support. Thus, I added a
> > Co-developed-by tag into a few patches.
> >
> > SW_TAGS vmalloc tagging support is straightforward. It reuses all of
> > the generic KASAN machinery, but uses shadow memory to store tags
> > instead of magic values. Naturally, vmalloc tagging requires adding
> > a few kasan_reset_tag() annotations to the vmalloc code.
> >
> > HW_TAGS vmalloc tagging support stands out. HW_TAGS KASAN is based on
> > Arm MTE, which can only assigns tags to physical memory. As a result,
> > HW_TAGS KASAN only tags vmalloc() allocations, which are backed by
> > page_alloc memory. It ignores vmap() and others.
> >
> > Changes in v3->v4:
> [...]
> > Andrey Konovalov (39):
> >   kasan, page_alloc: deduplicate should_skip_kasan_poison
> >   kasan, page_alloc: move tag_clear_highpage out of
> >     kernel_init_free_pages
> >   kasan, page_alloc: merge kasan_free_pages into free_pages_prepare
> >   kasan, page_alloc: simplify kasan_poison_pages call site
> >   kasan, page_alloc: init memory of skipped pages on free
> >   kasan: drop skip_kasan_poison variable in free_pages_prepare
> >   mm: clarify __GFP_ZEROTAGS comment
> >   kasan: only apply __GFP_ZEROTAGS when memory is zeroed
> >   kasan, page_alloc: refactor init checks in post_alloc_hook
> >   kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook
> >   kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook
> >   kasan, page_alloc: move SetPageSkipKASanPoison in post_alloc_hook
> >   kasan, page_alloc: move kernel_init_free_pages in post_alloc_hook
> >   kasan, page_alloc: rework kasan_unpoison_pages call site
> >   kasan: clean up metadata byte definitions
> >   kasan: define KASAN_VMALLOC_INVALID for SW_TAGS
> >   kasan, x86, arm64, s390: rename functions for modules shadow
> >   kasan, vmalloc: drop outdated VM_KASAN comment
> >   kasan: reorder vmalloc hooks
> >   kasan: add wrappers for vmalloc hooks
> >   kasan, vmalloc: reset tags in vmalloc functions
> >   kasan, fork: reset pointer tags of vmapped stacks
> >   kasan, arm64: reset pointer tags of vmapped stacks
> >   kasan, vmalloc: add vmalloc tagging for SW_TAGS
> >   kasan, vmalloc, arm64: mark vmalloc mappings as pgprot_tagged
> >   kasan, vmalloc: unpoison VM_ALLOC pages after mapping
> >   kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS
> >   kasan, page_alloc: allow skipping unpoisoning for HW_TAGS
> >   kasan, page_alloc: allow skipping memory init for HW_TAGS
> >   kasan, vmalloc: add vmalloc tagging for HW_TAGS
> >   kasan, vmalloc: only tag normal vmalloc allocations
> >   kasan, arm64: don't tag executable vmalloc allocations
> >   kasan: mark kasan_arg_stacktrace as __initdata
> >   kasan: simplify kasan_init_hw_tags
> >   kasan: add kasan.vmalloc command line flag
> >   kasan: allow enabling KASAN_VMALLOC and SW/HW_TAGS
> >   arm64: select KASAN_VMALLOC for SW/HW_TAGS modes
> >   kasan: documentation updates
> >   kasan: improve vmalloc tests
>
> Functionally it all looks good. So rather than acking every patch, for
> the whole series:
>
> Acked-by: Marco Elver <elver@...gle.com>
>
> ... and in case you do a v5, I've left some minor comments.

I will, thanks!

> Happy holidays!

Happy holidays to you too!