Commit c620677d authored Aug 01, 2019 by Qian Cai Committed by Alistair Delva Oct 23, 2019

UPSTREAM: arm64/mm: fix variable 'tag' set but not used



(Upstream commit 7732d20a160c76006c7fe7bca5178aea6af1d2e8).

When CONFIG_KASAN_SW_TAGS=n, set_tag() is compiled away. GCC throws a
warning,

mm/kasan/common.c: In function '__kasan_kmalloc':
mm/kasan/common.c:464:5: warning: variable 'tag' set but not used
[-Wunused-but-set-variable]
  u8 tag = 0xff;
     ^~~

Fix it by making __tag_set() a static inline function the same as
arch_kasan_set_tag() in mm/kasan/kasan.h for consistency because there
is a macro in arch/arm64/include/asm/kasan.h,

 #define arch_kasan_set_tag(addr, tag) __tag_set(addr, tag)

However, when CONFIG_DEBUG_VIRTUAL=n and CONFIG_SPARSEMEM_VMEMMAP=y,
page_to_virt() will call __tag_set() with incorrect type of a
parameter, so fix that as well. Also, still let page_to_virt() return
"void *" instead of "const void *", so will not need to add a similar
cast in lowmem_page_address().

Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Bug: 135692346
Change-Id: Iec54d8b8f0c986d7767b700c31be44066243c68f

parent 74e86642

arch/arm64/include/asm/memory.h

+7 −3

Original line number	Diff line number	Diff line
		@@ -226,7 +226,11 @@ static inline unsigned long kaslr_offset(void)
		#define __tag_reset(addr) untagged_addr(addr)
		#define __tag_get(addr) (__u8)((u64)(addr) >> 56)
		#else
		#define __tag_set(addr, tag) (addr)
		static inline const void __tag_set(const void addr, u8 tag)
		{
		return addr;
		}

		#define __tag_reset(addr) (addr)
		#define __tag_get(addr) 0
		#endif
		@@ -317,8 +321,8 @@ static inline void *phys_to_virt(phys_addr_t x)
		#define page_to_virt(page) ({ \
		unsigned long __addr = \
		((__page_to_voff(page)) \| PAGE_OFFSET); \
		unsigned long __addr_tag = \
		__tag_set(__addr, page_kasan_tag(page)); \
		const void *__addr_tag = \
		__tag_set((void *)__addr, page_kasan_tag(page)); \
		((void *)__addr_tag); \
		})