Re: [v5, 1/7] powerpc64/elfv1: Only dereference function descriptor for non-text symbols

[Michael Ellerman <patch-notifications@ellerman.id.au>]

On Thu, 2017-06-29 at 17:49:14 UTC, "Naveen N. Rao" wrote:
> Currently, we assume that the function pointer we receive in
> ppc_function_entry() points to a function descriptor. However, this is
> not always the case. In particular, assembly symbols without the right
> annotation do not have an associated function descriptor. Some of these
> symbols are added to the kprobe blacklist using _ASM_NOKPROBE_SYMBOL().
> 
> When such addresses are subsequently processed through
> arch_deref_entry_point() in populate_kprobe_blacklist(), we see the
> below errors during bootup:
>     [    0.663963] Failed to find blacklist at 7d9b02a648029b6c
>     [    0.663970] Failed to find blacklist at a14d03d0394a0001
>     [    0.663972] Failed to find blacklist at 7d5302a6f94d0388
>     [    0.663973] Failed to find blacklist at 48027d11e8610178
>     [    0.663974] Failed to find blacklist at f8010070f8410080
>     [    0.663976] Failed to find blacklist at 386100704801f89d
>     [    0.663977] Failed to find blacklist at 7d5302a6f94d00b0
> 
> Fix this by checking if the function pointer we receive in
> ppc_function_entry() already points to kernel text. If so, we just
> return it as is. If not, we assume that this is a function descriptor
> and proceed to dereference it.
> 
> Suggested-by: Nicholas Piggin <npiggin@gmail.com>
> Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/83e840c770f2c578bbbff478d62a44

cheers