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>

2 files changed, 9 insertions, 13 deletions

diff --git a/include/asm-x86_64/page.h b/include/asm-x86_64/page.h
index b17fc16ec2eb..4d04e2479569 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
diff --git a/include/asm-x86_64/pgtable.h b/include/asm-x86_64/pgtable.h
index 599993f6ba84..da3390faaea6 100644
--- a/include/asm-x86_64/pgtable.h
+++ b/include/asm-x86_64/pgtable.h
@@ -19,7 +19,7 @@ extern pmd_t level2_kernel_pgt[512];
 extern pgd_t init_level4_pgt[];
 extern unsigned long __supported_pte_mask;
 
-#define swapper_pg_dir ((pgd_t *)NULL)
+#define swapper_pg_dir init_level4_pgt
 
 extern void paging_init(void);
 extern void clear_kernel_mapping(unsigned long addr, unsigned long size);
@@ -29,7 +29,7 @@ extern void clear_kernel_mapping(unsigned long addr, unsigned long size);
  * for zero-mapped memory areas etc..
  */
 extern unsigned long empty_zero_page[PAGE_SIZE/sizeof(unsigned long)];
-#define ZERO_PAGE(vaddr) (pfn_to_page(__pa_symbol(&empty_zero_page) >> PAGE_SHIFT))
+#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
 
 #endif /* !__ASSEMBLY__ */