[PATCH 1/2] powerpc: kprobes: blacklist exception handlers

[Michael Ellerman]

"Naveen N. Rao" <naveen.n.rao at linux.vnet.ibm.com> writes:

> diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
> index 71286dfd76a0..59159337a097 100644
> --- a/arch/powerpc/kernel/kprobes.c
> +++ b/arch/powerpc/kernel/kprobes.c
> @@ -112,6 +113,14 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
>  	return addr;
>  }
>  
> +bool arch_within_kprobe_blacklist(unsigned long addr)
> +{
> +	return  (addr >= (unsigned long)__kprobes_text_start &&
> +		 addr < (unsigned long)__kprobes_text_end) ||
> +		(addr >= (unsigned long)_stext &&
> +		 addr < (unsigned long)__head_end);
> +}

This isn't quite right when the kernel is relocated.

_stext and __head_end will be updated to point to the relocated copy of
the kernel, eg:

# grep -e _stext /proc/kallsyms 
c000000002000000 T _stext

So you probably also want something like:

  if (_stext != PAGE_OFFSET &&
      addr >= PAGE_OFFSET &&
      addr < (PAGE_OFFSET + (__head_end - _stext)))
      return true;

But that's entirely untested :)

You can test the relocatable case by enabling CONFIG_RELOCATABLE_TEST.

cheers