Re: [PATCH] gas: support for .pushsection and .popsection pseudo ops for coff

On 18.07.2026 18:22, Johannes Khoshnazar-Thoma wrote:
> Current Linux kernels make heavy use of the .pushsection and
> .popsection pseudo ops. Normally, the Linux kernel is built
> as an ELF object, where the assembler supports those pseudo
> ops. When compiling the Linux kernel as a Windows/ReactOS
> driver however, it must be compiled as a COFF object, since
> the Windows/ReactOS kernel does not know how to load ELF
> binaries.
> 
> In order to be able to compile the Linux kernel as a COFF
> object (and further on as a PE32 native executable) the
> implementation of those pseudo ops has been copiied from
> the obj-elf.c support code to the obj-coff.c support code.
> It has been verified that the Linux kernel works without
> assembler errors when using an assembler with this patch.

First - don't you also need to support .previous then?

> --- a/gas/config/obj-coff.c
> +++ b/gas/config/obj-coff.c
> @@ -1536,6 +1536,32 @@ obj_coff_finalize_section_relocs (asection *sec, arelent **relocs,
>    return true;
>  }
>  
> +struct section_stack
> +{
> +  struct section_stack *next;
> +  segT seg;
> +  int subseg;

No matter that ELF uses int there, can this please be subsegT?

> +};
> +
> +static struct section_stack *section_stack;
> +
> +static void
> +obj_coff_popsection (int xxx ATTRIBUTE_UNUSED)

I understand the name is what ELF uses, but can this please be e.g. "ignore"
like obj_coff_section() had it before the change, and like many other directive
handler have it?

> +{
> +  struct section_stack *top = section_stack;
> +
> +  if (top == NULL)
> +    {
> +      as_warn (_(".popsection without corresponding .pushsection; ignored"));
> +      return;
> +    }
> +
> +  section_stack = top->next;
> +  subseg_set (top->seg, top->subseg);
> +  free (top);
> +}
> +
> +

Nit: No (new) double blank lines please.

> @@ -1691,6 +1717,17 @@ obj_coff_section (int ignore ATTRIBUTE_UNUSED)
>  	}
>      }
>  
> +  /* .pushsection implementation */
> +  if (push)

I don't think the comment adds any value here.

> +    {
> +      struct section_stack *elt;
> +      elt = XNEW (struct section_stack);

Can this please be the initializer of the variable?

> @@ -1903,6 +1940,8 @@ static const pseudo_typeS coff_pseudo_table[] =
>    {"sect.s", obj_coff_section, 0},
>    {"section", obj_coff_section, 0},
>    {"section.s", obj_coff_section, 0},
> +  {"pushsection", obj_coff_section, 1},
> +  {"popsection", obj_coff_popsection, 0},
>    /* FIXME: We ignore the MRI short attribute.  */
>    {"size", obj_coff_size, 0},
>    {"tag", obj_coff_tag, 0},

This table attempts to have its entries sorted by name. Please insert accordingly.

Also you didn't copy what elf_end() has; please do.

Jan