Subject: Re: [PATCH v5 2/2] [BUGFIX] kprobes: Fix "Failed to find blacklist" error on ia64 and ppc64

From: Michael Ellerman <[email-masked]>
Date: Tue, 15 Jul 2014 13:19:30 +1000

On Wed, 2014-07-02 at 07:00 +0000, Masami Hiramatsu wrote:
> On ia64 and ppc64, the function pointer does not point the
> entry address of the function, but the address of function
> discriptor (which contains the entry address and misc
> data.) Since the kprobes passes the function pointer stored
> by NOKPROBE_SYMBOL() to kallsyms_lookup_size_offset() for
> initalizing its blacklist, it fails and reports many errors
> as below.
> 
>   Failed to find blacklist 0001013168300000
>   Failed to find blacklist 0001013000f0a000
>   Failed to find blacklist 000101315f70a000
>   Failed to find blacklist 000101324c80a000
>   Failed to find blacklist 0001013063f0a000
>   Failed to find blacklist 000101327800a000
>   Failed to find blacklist 0001013277f0a000
>   Failed to find blacklist 000101315a70a000
>   Failed to find blacklist 0001013277e0a000
>   Failed to find blacklist 000101305a20a000
>   Failed to find blacklist 0001013277d0a000
>   Failed to find blacklist 00010130bdc0a000
>   Failed to find blacklist 00010130dc20a000
>   Failed to find blacklist 000101309a00a000
>   Failed to find blacklist 0001013277c0a000
>   Failed to find blacklist 0001013277b0a000
>   Failed to find blacklist 0001013277a0a000
>   Failed to find blacklist 000101327790a000
>   Failed to find blacklist 000101303140a000
>   Failed to find blacklist 0001013a3280a000
> 
> To fix this bug, this introduces function_entry() macro to
> retrieve the entry address from the given function pointer,
> and uses for kallsyms_lookup_size_offset() while initializing
> blacklist.
> 
> Changes in v5:
>  - Use arch_deref_entry_point() instead of function_entry().
> 
> Changes in v4:
>  - Add kernel_text_address() check for verifying the address.
>  - Moved on the latest linus tree.
> 
> Changes in v3:
>  - Fix a bug to get blacklist address based on function entry
>    instead of function descriptor. (Suzuki's work, Thanks!)
> 
> Changes in V2:
>  - Use function_entry() macro when lookin up symbols instead
>    of storing it.
>  - Update for the latest -next.
> 
> Signed-off-by: Masami Hiramatsu <[email-masked]>
> Reported-by: Tony Luck <[email-masked]>
> Tested-by: Tony Luck <[email-masked]>
> Cc: Michael Ellerman <[email-masked]>

Tested-by: Michael Ellerman <[email-masked]>
Acked-by: Michael Ellerman <[email-masked]> (for powerpc)

Ben, can you take this in your tree?

cheers