Re: [RFT PATCH -next ] [BUGFIX] kprobes: Fix "Failed to find blacklist" error on ia64 and ppc64

Masami Hiramatsu
2014-05-08T05:40:11Z

(2014/05/08 13:47), Ananth N Mavinakayanahalli wrote:
> On Wed, May 07, 2014 at 08:55:51PM +0900, Masami Hiramatsu wrote:
>
> ...
>
>> +#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.

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

Thank you,

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