Revert "[PATCH] x86: __pa and __pa_symbol address space separation"

This was broken.  It adds complexity, for no good reason.  Rather than
separate __pa() and __pa_symbol(), we should deprecate __pa_symbol(),
and preferably __pa() too - and just use "virt_to_phys()" instead, which
is more readable and has nicer semantics.

However, right now, just undo the separation, and make __pa_symbol() be
the exact same as __pa().  That fixes the bugs this patch introduced,
and we can do the fairly obvious cleanups later.

Do the new __phys_addr() function (which is now the actual workhorse for
the unified __pa()/__pa_symbol()) as a real external function, that way
all the potential issues with compile/link-time optimizations of
constant symbol addresses go away, and we can also, if we choose to, add
more sanity-checking of the argument.

Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 11 deletions

diff --git a/include/asm-x86_64/page.h b/include/asm-x86_64/page.h
index b17fc16..4d04e24 100644
--- a/include/asm-x86_64/page.h
+++ b/include/asm-x86_64/page.h
@@ -94,26 +94,22 @@ extern unsigned long phys_base;
 
 #define KERNEL_TEXT_SIZE  (40*1024*1024)
 #define KERNEL_TEXT_START 0xffffffff80000000
+#define PAGE_OFFSET		__PAGE_OFFSET
 
 #ifndef __ASSEMBLY__
 
 #include <asm/bug.h>
 
-#endif /* __ASSEMBLY__ */
+extern unsigned long __phys_addr(unsigned long);
 
-#define PAGE_OFFSET		__PAGE_OFFSET
+#endif /* __ASSEMBLY__ */
 
-/* Note: __pa(&symbol_visible_to_c) should be always replaced with __pa_symbol.
-   Otherwise you risk miscompilation. */
-#define __pa(x)			((unsigned long)(x) - PAGE_OFFSET)
-/* __pa_symbol should be used for C visible symbols.
-   This seems to be the official gcc blessed way to do such arithmetic. */ 
-#define __pa_symbol(x)		\
-	({unsigned long v;  \
-	  asm("" : "=r" (v) : "0" (x)); \
-	  ((v - __START_KERNEL_map) + phys_base); })
+#define __pa(x)		__phys_addr((unsigned long)(x))
+#define __pa_symbol(x)	__phys_addr((unsigned long)(x))
 
 #define __va(x)			((void *)((unsigned long)(x)+PAGE_OFFSET))
+#define __boot_va(x)		__va(x)
+#define __boot_pa(x)		__pa(x)
 #ifdef CONFIG_FLATMEM
 #define pfn_valid(pfn)		((pfn) < end_pfn)
 #endif