On Mon, Dec 6, 2021 at 10:22 PM [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-v2

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.

I'll keep the patchset based on the mainline for now. Once the
high-level issues are resolved, I'll rebase onto mm - there might be
a few conflicts right now.

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 v1->v2:
- Move memory init for vmalloc() into vmalloc code for HW_TAGS KASAN.
- Minor fixes and code reshuffling, see patches for lists of changes.

Thanks!

FTR, I found a few issues with a tag propagating to PC (in BPF JIT and
a few other places). Will address them in v3.

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