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

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>
This commit is contained in:
Qian Cai 2019-08-01 10:47:05 -04:00 committed by Will Deacon
parent 7d4e2dcf31
commit 7732d20a16
1 changed files with 7 additions and 3 deletions
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10
arch/arm64/include/asm/memory.h
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@ -210,7 +210,11 @@ extern u64 vabits_user;
#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
@ -301,8 +305,8 @@ 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); \
})