(2014/05/08 15:16), Ananth N Mavinakayanahalli wrote:

On Thu, May 08, 2014 at 02:40:00PM +0900, Masami Hiramatsu wrote:

quoted

(2014/05/08 13:47), Ananth N Mavinakayanahalli wrote:

quoted

On Wed, May 07, 2014 at 08:55:51PM +0900, Masami Hiramatsu wrote:

...

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+#if defined(CONFIG_PPC64) && (!defined(_CALL_ELF) || _CALL_ELF == 1)
+/*
+ * On PPC64 ABIv1 the function pointer actually points to the
+ * function's descriptor. The first entry in the descriptor is the
+ * address of the function text.
+ */
+#define constant_function_entry(fn)	(((func_descr_t *)(fn))->entry)
+#else
+#define constant_function_entry(fn)	((unsigned long)(fn))
+#endif
+
 #endif /* __ASSEMBLY__ */

Hi Masami,

You could just use ppc_function_entry() instead.

No, I think ppc_function_entry() has two problems (on the latest -next kernel)

At first, that is an inlined functions which is not applied in build time.
Since the NOKPROBE_SYMBOL() is used outside of any functions as like as
EXPORT_SYMBOL(), we can only use preprocessed macros.
Next, on PPC64 ABI*v2*, ppc_function_entry() returns local function entry,
which seems global function entry + 2 insns. I'm not sure about implementation
of the kallsyms on PPC64 ABIv2, but I guess we need global function entry
for kallsyms.

ABIv2 does away with function descriptors and Anton fixed up that
routine to handle the change (the +2 is an artefact of that).

Hmm, do you mean that the address +2 is the actual entry point?
I'd like to know which address is same as the address shown in /proc/kallsyms.

quoted

BTW, could you test this patch on the latest -next tree on PPC64 if possible?

I'll test it, but it may take a bit.

Thanks for your help!

Ananth

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com