Re: [PATCH v3 08/12] asm-generic: Refactor dereference_[kernel]_function_descriptor()

[Michael Ellerman <mpe@xxxxxxxxxxxxxx>]

Christophe Leroy <christophe.leroy@xxxxxxxxxx> writes:
> diff --git a/kernel/extable.c b/kernel/extable.c
> index b0ea5eb0c3b4..1ef13789bea9 100644
> --- a/kernel/extable.c
> +++ b/kernel/extable.c
> @@ -159,12 +160,32 @@ int kernel_text_address(unsigned long addr)
>  }
>  
>  /*
> - * On some architectures (PPC64, IA64) function pointers
> + * On some architectures (PPC64, IA64, PARISC) function pointers
>   * are actually only tokens to some data that then holds the
>   * real function address. As a result, to find if a function
>   * pointer is part of the kernel text, we need to do some
>   * special dereferencing first.
>   */
> +#ifdef CONFIG_HAVE_FUNCTION_DESCRIPTORS
> +void *dereference_function_descriptor(void *ptr)
> +{
> +	func_desc_t *desc = ptr;
> +	void *p;
> +
> +	if (!get_kernel_nofault(p, (void *)&desc->addr))
> +		ptr = p;
> +	return ptr;
> +}

This needs an EXPORT_SYMBOL_GPL(), otherwise the build breaks after
patch 10 with CONFIG_LKDTM=m.

cheers