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uaccess: add noop untagged_addr definition

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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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2019-06-04 14:04:47 +02:00 committed by Linus Torvalds
parent d18c7e9d6e
commit d93445225c
1 changed files with 11 additions and 0 deletions
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11
include/linux/mm.h
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@ -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