This reverts commit e5b8d92189.
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>
In copy_highpage() the `kto` and `kfrom` local variables are pointers to
struct page, but these are used to hold arbitrary pointers to kernel memory
. Each call to page_address() returns a void pointer to memory associated
with the relevant page, and copy_page() expects void pointers to this
memory.
This inconsistency was introduced in commit 2563776b41 ("arm64: mte:
Tags-aware copy_{user_,}highpage() implementations") and while this
doesn't appear to be harmful in practice it is clearly wrong.
Correct this by making `kto` and `kfrom` void pointers.
Fixes: 2563776b41 ("arm64: mte: Tags-aware copy_{user_,}highpage() implementations")
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Link: https://lore.kernel.org/r/20220420030418.3189040-3-tongtiangen@huawei.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The hardware tag-based KASAN for compatibility with the other modes stores
the tag associated to a page in page->flags. Due to this the kernel
faults on access when it allocates a page with an initial tag and the user
changes the tags.
Reset the tag associated by the kernel to a page in all the meaningful
places to prevent kernel faults on access.
Note: An alternative to this approach could be to modify page_to_virt().
This though could end up being racy, in fact if a CPU checks the
PG_mte_tagged bit and decides that the page is not tagged but another CPU
maps the same with PROT_MTE and becomes tagged the subsequent kernel
access would fail.
Link: https://lkml.kernel.org/r/9073d4e973747a6f78d5bdd7ebe17f290d087096.1606161801.git.andreyknvl@google.com
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When the Memory Tagging Extension is enabled, the tags need to be
preserved across page copy (e.g. for copy-on-write, page migration).
Introduce MTE-aware copy_{user_,}highpage() functions to copy tags to
the destination if the source page has the PG_mte_tagged flag set.
copy_user_page() does not need to handle tag copying since, with this
patch, it is only called by the DAX code where there is no source page
structure (and no source tags).
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Based on 1 normalized pattern(s):
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 this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program if not see http www gnu org
licenses
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 503 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The __cpu_clear_user_page() and __cpu_copy_user_page() functions
are not currently exported. This prevents modules from using
clear_user_page() and copy_user_page().
Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This patch adds support for the handling of the MMU faults (exception
entry code introduced by a previous patch) and page table management.
The user translation table is pointed to by TTBR0 and the kernel one
(swapper_pg_dir) by TTBR1. There is no translation information shared or
address space overlapping between user and kernel page tables.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
