Messages in this thread Patch in this message | | | From | Namhyung Kim <> | Subject | [PATCH] x86: add a comment to __pa_symbol | Date | Wed, 11 Aug 2010 15:37:41 +0900 |
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Until all supported versions of gcc recognize -fno-strict-overflow, we should keep the RELOC_HIDE magic on __pa_symbol(). Comment it.
Signed-off-by: Namhyung Kim <namhyung@gmail.com> Suggested-by: Ingo Molnar <mingo@elte.hu>
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I hope I'm doing right. :-)
arch/x86/include/asm/page.h | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h index 625c3f0..06cb6f3 100644 --- a/arch/x86/include/asm/page.h +++ b/arch/x86/include/asm/page.h @@ -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. + */ #define __pa_symbol(x) __pa(__phys_reloc_hide((unsigned long)(x))) #define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET)) -- 1.7.0.4
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