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Catalin Marinas 20794545c1 arm64: kasan: Revert "arm64: mte: reset the page tag in page->flags"

This reverts commit e5b8d9218951e59df986f627ec93569a0d22149b.

Pages mapped in user-space with PROT_MTE have the allocation tags either
zeroed or copied/restored to some user values. In order for the kernel
to access such pages via page_address(), resetting the tag in
page->flags was necessary. This tag resetting was deferred to
set_pte_at() -> mte_sync_page_tags() but it can race with another CPU
reading the flags (via page_to_virt()):

P0 (mte_sync_page_tags):	P1 (memcpy from virt_to_page):
				  Rflags!=0xff
  Wflags=0xff
  DMB (doesn't help)
  Wtags=0
				  Rtags=0   // fault

Since now the post_alloc_hook() function resets the page->flags tag when
unpoisoning is skipped for user pages (including the __GFP_ZEROTAGS
case), revert the arm64 commit calling page_kasan_tag_reset().

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Peter Collingbourne <pcc@google.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20220610152141.2148929-5-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

2022-07-07 10:48:37 +01:00

cache.S

arm64: mm: Don't invalidate FROM_DEVICE buffers at start of DMA transfer

2022-06-17 19:06:06 +01:00

context.c

arm64: mm: Use asid feature macro for cheanup

2021-12-10 18:24:20 +00:00

copypage.c

arm64: kasan: Revert "arm64: mte: reset the page tag in page->flags"

2022-07-07 10:48:37 +01:00

dma-mapping.c

arm/xen: Introduce xen_setup_dma_ops()