Subject: [PATCH 3/8] arm64: memory: Rewrite default page_to_virt()/virt_to_page()

From: Will Deacon <[email-masked]>
Date: Tue, 13 Aug 2019 18:01:44 +0100

The default implementations of page_to_virt() and virt_to_page() are
fairly confusing to read and the former evaluates its 'page' parameter
twice in the macro

Rewrite them so that the computation is expressed as 'base + index' in
both cases and the parameter is always evaluated exactly once.

Signed-off-by: Will Deacon <[email-masked]>
---
 arch/arm64/include/asm/memory.h | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 47b4dc73b8bf..77074b3a1025 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -313,19 +313,18 @@ static inline void *phys_to_virt(phys_addr_t x)
 #if !defined(CONFIG_SPARSEMEM_VMEMMAP) || defined(CONFIG_DEBUG_VIRTUAL)
 #define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
 #else
-#define __virt_to_pgoff(kaddr)	(((u64)(kaddr) - PAGE_OFFSET) / PAGE_SIZE * sizeof(struct page))
-#define __page_to_voff(kaddr)	(((u64)(kaddr) - VMEMMAP_START) * PAGE_SIZE / sizeof(struct page))
-
-#define page_to_virt(page)	({					\
-	unsigned long __addr =						\
-		((__page_to_voff(page)) + PAGE_OFFSET);			\
-	const void *__addr_tag =					\
-		__tag_set((void *)__addr, page_kasan_tag(page));	\
-	((void *)__addr_tag);						\
+#define page_to_virt(x)	({						\
+	__typeof__(x) __page = x;					\
+	u64 __idx = ((u64)__page - VMEMMAP_START) / sizeof(struct page);\
+	u64 __addr = PAGE_OFFSET + (__idx * PAGE_SIZE);			\
+	(void *)__tag_set((const void *)__addr, page_kasan_tag(__page));\
 })
 
-#define virt_to_page(vaddr)	\
-	((struct page *)((__virt_to_pgoff(__tag_reset(vaddr))) + VMEMMAP_START))
+#define virt_to_page(x)	({						\
+	u64 __idx = (__tag_reset((u64)x) - PAGE_OFFSET) / PAGE_SIZE;	\
+	u64 __addr = VMEMMAP_START + (__idx * sizeof(struct page));	\
+	(struct page *)__addr;						\
+})
 #endif
 
 #define virt_addr_valid(addr)	({					\
-- 
2.11.0

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