On Mon, Jun 27, 2022 at 09:05:50PM +0200, Helge Deller wrote:
> In the kernel image vmlinux.lds.S linker scripts the .altinstructions
> and __bug_table sections are 32- or 64-bit aligned because they hold 32-
> and/or 64-bit values.
>
> But for modules the module.lds.S linker script doesn't define a default
> alignment yet, so the linker chooses the default byte-alignment, which
> then leads to unnecessary unaligned memory accesses at runtime.
>
> This patch adds the missing alignments.
>
> Signed-off-by: Helge Deller <deller@xxxxxx>
Good catch but does this fix a real world issue? When are
altinstructions used for modules? When are alternatives used
for modules?
How did you notice this issue?
This information should go into the commit log.
Luis
> ---
> scripts/module.lds.S | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/scripts/module.lds.S b/scripts/module.lds.S
> index 1d0e1e4dc3d2..3a3aa2354ed8 100644
> --- a/scripts/module.lds.S
> +++ b/scripts/module.lds.S
> @@ -27,6 +27,8 @@ SECTIONS {
> .ctors 0 : ALIGN(8) { *(SORT(.ctors.*)) *(.ctors) }
> .init_array 0 : ALIGN(8) { *(SORT(.init_array.*)) *(.init_array) }
>
> + .altinstructions 0 : ALIGN(8) { KEEP(*(.altinstructions)) }
> + __bug_table 0 : ALIGN(8) { KEEP(*(__bug_table)) }
> __jump_table 0 : ALIGN(8) { KEEP(*(__jump_table)) }
>
> __patchable_function_entries : { *(__patchable_function_entries) }
> --
> 2.35.3
>
