[PATCH v2] uaccess: add noop untagged_addr definition

From: Andrey Konovalov <andreyknvl@google.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
	linux-arm-kernel@lists.infradead.org,
	 sparclinux@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Kostya Serebryany <kcc@google.com>,
	Khalid Aziz <khalid.aziz@oracle.com>,
	Felix Kuehling <Felix.Kuehling@amd.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Jacob Bramley <Jacob.Bramley@arm.com>,
	Leon Romanovsky <leon@kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	Jason Gunthorpe <jgg@ziepe.ca>, Dave Martin <Dave.Martin@arm.com>,
	Evgeniy Stepanov <eugenis@google.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Dmitry Vyukov <dvyukov@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Yishai Hadas <yishaih@mellanox.com>,
	Jens Wiklander <jens.wiklander@linaro.org>,
	Lee Smith <Lee.Smith@arm.com>,
	Alexander Deucher <Alexander.Deucher@amd.com>,
	Andrew Morton <akpm@linux-foundation.org>, enh <enh@google.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Christian Koenig <Christian.Koenig@amd.com>,
	Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Subject: [PATCH v2] uaccess: add noop untagged_addr definition
Date: Tue,  4 Jun 2019 14:04:47 +0200	[thread overview]
Message-ID: <c8311f9b759e254308a8e57d9f6eb17728a686a7.1559649879.git.andreyknvl@google.com> (raw)

Architectures that support memory tagging have a need to perform untagging
(stripping the tag) in various parts of the kernel. This patch adds an
untagged_addr() macro, which is defined as noop for architectures that do
not support memory tagging. The oncoming patch series will define it at
least for sparc64 and arm64.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 include/linux/mm.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e8834ac32b7..dd0b5f4e1e45 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -99,6 +99,17 @@ extern int mmap_rnd_compat_bits __read_mostly;
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 
+/*
+ * Architectures that support memory tagging (assigning tags to memory regions,
+ * embedding these tags into addresses that point to these memory regions, and
+ * checking that the memory and the pointer tags match on memory accesses)
+ * redefine this macro to strip tags from pointers.
+ * It's defined as noop for arcitectures that don't support memory tagging.
+ */
+#ifndef untagged_addr
+#define untagged_addr(addr) (addr)
+#endif
+
 #ifndef __pa_symbol
 #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
 #endif
-- 
2.22.0.rc1.311.g5d7573a151-goog


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