[PATCH] i386: define __pa_symbol()

On x86_64 we have to be careful with calculating the physical
address of kernel symbols.  Both because of compiler odditities
and because the symbols live in a different range of the virtual
address space.

Having a defintition of __pa_symbol that works on both x86_64 and
i386 simplifies writing code that works for both x86_64 and
i386 that has these kinds of dependencies.

So this patch adds the trivial i386 __pa_symbol definition.

Added assembly magic similar to RELOC_HIDE as suggested by Andi Kleen.
Just picked it up from x86_64.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>

diff --git a/include/asm-i386/page.h b/include/asm-i386/page.h
index f5bf544c729a373aa4ec1832aa9fa3cd55a13800..5a70501291d695bbe616152074fb6f89fb73afdd 100644 (file)
--- a/include/asm-i386/page.h
+++ b/include/asm-i386/page.h
@@ -124,6 +124,9 @@ extern int page_is_ram(unsigned long pagenr);
 #define VMALLOC_RESERVE                ((unsigned long)__VMALLOC_RESERVE)
 #define MAXMEM                 (-__PAGE_OFFSET-__VMALLOC_RESERVE)
 #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)          __pa(RELOC_HIDE((unsigned long)(x),0))
 #define __va(x)                        ((void *)((unsigned long)(x)+PAGE_OFFSET))
 #define pfn_to_kaddr(pfn)      __va((pfn) << PAGE_SHIFT)
 #ifdef CONFIG_FLATMEM