x86/mm: Unify __phys_addr_symbol()

There are two implementations on 64-bit, depending on CONFIG_DEBUG_VIRTUAL,
but they differ only regarding the presence of VIRTUAL_BUG_ON, which is
already ifdef'd on CONFIG_DEBUG_VIRTUAL.

To avoid adding a function call on non-LTO non-DEBUG_VIRTUAL builds, move the
function into the header. (Note the function is already only used on 64-bit).

Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://patch.msgid.link/all/20250813-phys-addr-cleanup-v1-1-19e334b1c466@google.com/

Author: bjackman

arch/x86/include/asm/page_64.h

@@ -9,6 +9,7 @@
 #include <asm/alternative.h>
 
 #include <linux/kmsan-checks.h>
+#include <linux/mmdebug.h>
 
 /* duplicated to the one in bootmem.h */
 extern unsigned long max_pfn;
@@ -31,13 +32,20 @@ static __always_inline unsigned long __phys_addr_nodebug(unsigned long x)
 
 #ifdef CONFIG_DEBUG_VIRTUAL
 extern unsigned long __phys_addr(unsigned long);
-extern unsigned long __phys_addr_symbol(unsigned long);
 #else
 #define __phys_addr(x)		__phys_addr_nodebug(x)
-#define __phys_addr_symbol(x) \
-	((unsigned long)(x) - __START_KERNEL_map + phys_base)
 #endif
 
+static inline unsigned long __phys_addr_symbol(unsigned long x)
+{
+	unsigned long y = x - __START_KERNEL_map;
+
+	/* only check upper bounds since lower bounds will trigger carry */
+	VIRTUAL_BUG_ON(y >= KERNEL_IMAGE_SIZE);
+
+	return y + phys_base;
+}
+
 #define __phys_reloc_hide(x)	(x)
 
 void clear_page_orig(void *page);

arch/x86/mm/physaddr.c

@@ -31,17 +31,6 @@ unsigned long __phys_addr(unsigned long x)
 	return x;
 }
 EXPORT_SYMBOL(__phys_addr);
-
-unsigned long __phys_addr_symbol(unsigned long x)
-{
-	unsigned long y = x - __START_KERNEL_map;
-
-	/* only check upper bounds since lower bounds will trigger carry */
-	VIRTUAL_BUG_ON(y >= KERNEL_IMAGE_SIZE);
-
-	return y + phys_base;
-}
-EXPORT_SYMBOL(__phys_addr_symbol);
 #endif
 
 bool __virt_addr_valid(unsigned long x)