Re: [PATCH v2] x86: Put trampoline in separate .init.trampoline section

[Jan Beulich <jbeulich@xxxxxxxx>]

On 11.09.2024 11:55, Frediano Ziglio wrote:
> --- a/xen/arch/x86/boot/head.S
> +++ b/xen/arch/x86/boot/head.S
> @@ -882,8 +882,9 @@ cmdline_parse_early:
>  reloc:
>          .incbin "reloc.bin"
>  
> +#include "x86_64.S"
> +
> +        .section .init.trampoline, "aw", @progbits
>  ENTRY(trampoline_start)
>  #include "trampoline.S"
>  ENTRY(trampoline_end)

Hmm, nice - this turns out rather easier than I first thought.

> --- a/xen/arch/x86/xen.lds.S
> +++ b/xen/arch/x86/xen.lds.S
> @@ -269,6 +269,11 @@ SECTIONS
>         __ctors_end = .;
>    } PHDR(text)
>  
> +  . = ALIGN(PAGE_SIZE);

Why? There's no special alignment right now.

> +  DECL_SECTION(.init.trampoline) {
> +       *(.init.trampoline)
> +  } PHDR(text)
> +
>  #ifndef EFI

If this is to be a separate section also for ELF, I think that
wants mentioning explicitly. "Easily disassemble" is too vague
a reason for my taste.

Jan