Messages in this thread | | | Date | Wed, 23 Aug 2006 20:00:59 +0800 | From | "Dong Feng" <> | Subject | Unnecessary Relocation Hiding? |
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Hi, all,
I have a question. Why shall we need a RELOC_HIDE() macro in the definition of per_cpu()? Maybe the question is actually why we need macro RELOC_HIDE() at all. I changed the following line in include/asm-generic/percpu.h, from
#define per_cpu(var, cpu) (*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu]))
to
#define per_cpu(var, cpu) (*((unsigned long)(&per_cpu__##var) + __per_cpu_offset[cpu]))
I recompiled the code and it works well on my Intel Dual-core laptop. It essentially the same as to change the definition of RELOC_HIDE(), from
#define RELOC_HIDE(ptr, off) \ ({ unsigned long __ptr; \ __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ (typeof(ptr)) (__ptr + (off)); })
to
#define RELOC_HIDE(ptr, off) \ ({ unsigned long __ptr; \ __ptr = (unsigned long)ptr; \ (typeof(ptr)) (__ptr + (off)); })
Why shouldn't we have a pure C solution in this part?
Best Regards. Feng,Dong - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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