uaccess: add noop untagged_addr definition
authorAndrey Konovalov <andreyknvl@google.com>
Tue, 4 Jun 2019 12:04:47 +0000 (14:04 +0200)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 7 Jun 2019 20:09:06 +0000 (13:09 -0700)
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>
include/linux/mm.h

index 0e8834ac32b76c74c965abec1a84b54a55e9e8f5..dd0b5f4e1e45acaad867296c3fd28bf2215af581 100644 (file)
@@ -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