[PATCH] arm64/scs: Fix handling of advance_loc4

[Will Deacon]

[+Ard]

On Tue, Mar 10, 2026 at 03:15:56PM +0100, Pepper Gray wrote:
> DW_CFA_advance_loc4 is defined but no handler is implemented. Its
> CFA opcode defaults to EDYNSCS_INVALID_CFA_OPCODE triggering an
> error which wrongfully prevents modules from loading.

Can you provide some instructions for reproducing this, please? For
example, which toolchain you are using and which module are you building?

> Signed-off-by: Pepper Gray <hello at peppergray.xyz>
> ---
>  arch/arm64/kernel/pi/patch-scs.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/arm64/kernel/pi/patch-scs.c b/arch/arm64/kernel/pi/patch-scs.c
> index bbe7d30ed12b32..dac568e4a54f23 100644
> --- a/arch/arm64/kernel/pi/patch-scs.c
> +++ b/arch/arm64/kernel/pi/patch-scs.c
> @@ -192,6 +192,14 @@ static int scs_handle_fde_frame(const struct
> eh_frame *frame,
>   size -= 2;
>   break;
> 
> + case DW_CFA_advance_loc4:
> + loc += *opcode++ * code_alignment_factor;
> + loc += (*opcode++ << 8) * code_alignment_factor;
> + loc += (*opcode++ << 16) * code_alignment_factor;
> + loc += (*opcode++ << 24) * code_alignment_factor;
> + size -= 4;
> + break;

This looks like it's whitespace-mangled to me.

Will