[PATCH v2 3/4] powerpc/bpf: implement bpf_arch_text_invalidate for bpf_prog_pack

[Song Liu]

On Thu, Mar 9, 2023 at 10:02 AM Hari Bathini <hbathini at linux.ibm.com> wrote:
>
> Implement bpf_arch_text_invalidate and use it to fill unused part of
> the bpf_prog_pack with trap instructions when a BPF program is freed.
>
> Signed-off-by: Hari Bathini <hbathini at linux.ibm.com>
> ---
>  arch/powerpc/net/bpf_jit_comp.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
> index 0a70319116d1..d1794d9f0154 100644
> --- a/arch/powerpc/net/bpf_jit_comp.c
> +++ b/arch/powerpc/net/bpf_jit_comp.c
> @@ -293,3 +293,18 @@ void *bpf_arch_text_copy(void *dst, void *src, size_t len)
>
>         return ret;
>  }
> +
> +int bpf_arch_text_invalidate(void *dst, size_t len)
> +{
> +       u32 inst = BREAKPOINT_INSTRUCTION;
> +       int ret = -EINVAL;

No need to set to -EINVAL here.

> +
> +       if (WARN_ON_ONCE(core_kernel_text((unsigned long)dst)))
> +               return ret;

Just return -EINVAL instead.

> +
> +       mutex_lock(&text_mutex);
> +       ret = patch_instructions(dst, &inst, true, len);
> +       mutex_unlock(&text_mutex);
> +
> +       return ret;
> +}
> --
> 2.39.2
>