arm64: memory: Fix virt_addr_valid() using __is_lm_address()

virt_addr_valid() is intended to test whether or not the passed address
is a valid linear map address. Unfortunately, it relies on
_virt_addr_is_linear() which is broken because it assumes the linear
map is at the top of the address space, which it no longer is.

Reimplement virt_addr_valid() using __is_lm_address() and remove
_virt_addr_is_linear() entirely. At the same time, ensure we evaluate
the macro parameter only once and move it within the __ASSEMBLY__ block.

Reported-by: Qian Cai <cai@lca.pw>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Fixes: 14c127c ("arm64: mm: Flip kernel VA space")
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/include/asm/memory.h

@@ -242,11 +242,11 @@ static inline const void *__tag_set(const void *addr, u8 tag)
 
 
 /*
- * The linear kernel range starts in the middle of the virtual adddress
+ * The linear kernel range starts at the bottom of the virtual address
  * space. Testing the top bit for the start of the region is a
- * sufficient check.
+ * sufficient check and avoids having to worry about the tag.
  */
-#define __is_lm_address(addr)	(!((addr) & BIT(vabits_actual - 1)))
+#define __is_lm_address(addr)	(!(((u64)addr) & BIT(vabits_actual - 1)))
 
 #define __lm_to_phys(addr)	(((addr) + physvirt_offset))
 #define __kimg_to_phys(addr)	((addr) - kimage_voffset)
@@ -326,13 +326,13 @@ static inline void *phys_to_virt(phys_addr_t x)
 
 #define virt_to_page(vaddr)	((struct page *)((__virt_to_pgoff(vaddr)) + VMEMMAP_START))
 #endif
-#endif
 
-#define _virt_addr_is_linear(kaddr)	\
-	(__tag_reset((u64)(kaddr)) >= PAGE_OFFSET)
+#define virt_addr_valid(addr)	({					\
+	__typeof__(addr) __addr = addr;					\
+	__is_lm_address(__addr) && pfn_valid(virt_to_pfn(__addr));	\
+})
 
-#define virt_addr_valid(kaddr)		\
-	(_virt_addr_is_linear(kaddr) && pfn_valid(virt_to_pfn(kaddr)))
+#endif
 
 /*
  * Given that the GIC architecture permits ITS implementations that can only be