Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-11 22:51:42 +00:00
Code Issues Packages Projects Releases Wiki Activity

x86: Document __phys_reloc_hide() usage in __pa_symbol()

Browse Source 
Until all supported versions of gcc recognize
-fno-strict-overflow, we should keep the RELOC_HIDE() magic in
__pa_symbol(). Comment it.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
LKML-Reference: <1281508661-29507-1-git-send-email-namhyung@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Namhyung Kim 2010-08-11 15:37:41 +09:00 committed by Ingo Molnar
parent 5989cd6a1c
commit 8fd49936a8
1 changed files with 7 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/x86/include/asm/page.h
View File

@ -37,6 +37,13 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
#define __pa_nodebug(x) __phys_addr_nodebug((unsigned long)(x))
/* __pa_symbol should be used for C visible symbols.
This seems to be the official gcc blessed way to do such arithmetic. */
/*
* We need __phys_reloc_hide() here because gcc may assume that there is no
* overflow during __pa() calculation and can optimize it unexpectedly.
* Newer versions of gcc provide -fno-strict-overflow switch to handle this
* case properly. Once all supported versions of gcc understand it, we can
* remove this Voodoo magic stuff. (i.e. once gcc3.x is deprecated)
*/
#define __pa_symbol(x) __pa(__phys_reloc_hide((unsigned long)(x)))
#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))