On Mon, 20 Dec 2021 at 22:58, [off-list ref] wrote:

From: Andrey Konovalov <redacted>

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  kasan, vmalloc: drop outdated VM_KASAN comment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@google.com>

... and in case you do a v5, I've left some minor comments.

Happy holidays!

Thanks,
-- Marco