Re: [PATCH v2 4/4] kernel: add support for init_array constructors

[Rusty Russell]

Frantisek Hrbata <fhrbata@xxxxxxxxxx> writes:
> This adds the .init_array section as yet another section with constructors. This
> is needed because gcc could add __gcov_init calls to .init_array or .ctors
> section, depending on gcc version.
>
> v2: - reuse mod->ctors for .init_array section for modules, because gcc uses
>       .ctors or .init_array, but not both at the same time
>
> Signed-off-by: Frantisek Hrbata <fhrbata@xxxxxxxxxx>

Might be nice to document which gcc version changed this, so people can
choose whether to cherry-pick this change?

Acked-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

> ---
>  include/asm-generic/vmlinux.lds.h | 1 +
>  kernel/module.c                   | 3 +++
>  2 files changed, 4 insertions(+)
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 69732d2..c55d8d9 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -468,6 +468,7 @@
>  #define KERNEL_CTORS()	. = ALIGN(8);			   \
>  			VMLINUX_SYMBOL(__ctors_start) = .; \
>  			*(.ctors)			   \
> +			*(.init_array)			   \
>  			VMLINUX_SYMBOL(__ctors_end) = .;
>  #else
>  #define KERNEL_CTORS()
> diff --git a/kernel/module.c b/kernel/module.c
> index 2069158..bbbd953 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -2760,6 +2760,9 @@ static void find_module_sections(struct module *mod, struct load_info *info)
>  #ifdef CONFIG_CONSTRUCTORS
>  	mod->ctors = section_objs(info, ".ctors",
>  				  sizeof(*mod->ctors), &mod->num_ctors);
> +	if (!mod->ctors)
> +		mod->ctors = section_objs(info, ".init_array",
> +				sizeof(*mod->ctors), &mod->num_ctors);
>  #endif
>  
>  #ifdef CONFIG_TRACEPOINTS
> -- 
> 1.8.3.1
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