Subject: Re: [PATCH v4 06/15] mm/execmem, arch: convert simple overrides of module_alloc to execmem

From: Peter Zijlstra <[email-masked]>
Date: Mon, 15 Apr 2024 10:03:21 +0200

On Thu, Apr 11, 2024 at 07:00:42PM +0300, Mike Rapoport wrote:
> +static struct execmem_info execmem_info __ro_after_init = {
> +	.ranges = {
> +		[EXECMEM_DEFAULT] = {
> +			.start = MODULES_VADDR,
> +			.end = MODULES_END,
> +			.alignment = 1,
> +		},
> +	},
> +};
> +
> +struct execmem_info __init *execmem_arch_setup(void)
>  {
> +	execmem_info.ranges[EXECMEM_DEFAULT].pgprot = PAGE_KERNEL;
> +
> +	return &execmem_info;
>  }

> +static struct execmem_info execmem_info __ro_after_init = {
> +	.ranges = {
> +		[EXECMEM_DEFAULT] = {
> +			.start = MODULES_VADDR,
> +			.end = MODULES_END,
> +			.pgprot = PAGE_KERNEL_EXEC,
> +			.alignment = 1,
> +		},
> +	},
> +};
> +
> +struct execmem_info __init *execmem_arch_setup(void)
>  {
> +	return &execmem_info;
>  }

> +static struct execmem_info execmem_info __ro_after_init = {
> +	.ranges = {
> +		[EXECMEM_DEFAULT] = {
> +			.pgprot = PAGE_KERNEL_RWX,
> +			.alignment = 1,
> +		},
> +	},
> +};
> +
> +struct execmem_info __init *execmem_arch_setup(void)
>  {
> +	execmem_info.ranges[EXECMEM_DEFAULT].start = VMALLOC_START;
> +	execmem_info.ranges[EXECMEM_DEFAULT].end = VMALLOC_END;
> +
> +	return &execmem_info;
>  }

> +static struct execmem_info execmem_info __ro_after_init = {
> +	.ranges = {
> +		[EXECMEM_DEFAULT] = {
> +			.pgprot = PAGE_KERNEL,
> +			.alignment = 1,
> +		},
> +	},
> +};
> +
> +struct execmem_info __init *execmem_arch_setup(void)
>  {
> +	execmem_info.ranges[EXECMEM_DEFAULT].start = MODULES_VADDR;
> +	execmem_info.ranges[EXECMEM_DEFAULT].end = MODULES_END;
> +
> +	return &execmem_info;
>  }

> +static struct execmem_info execmem_info __ro_after_init = {
> +	.ranges = {
> +		[EXECMEM_DEFAULT] = {
>  #ifdef CONFIG_SPARC64
> +			.start = MODULES_VADDR,
> +			.end = MODULES_END,
>  #else
> +			.start = VMALLOC_START,
> +			.end = VMALLOC_END,
> +#endif
> +			.alignment = 1,
> +		},
> +	},
> +};
> +
> +struct execmem_info __init *execmem_arch_setup(void)
>  {
> +	execmem_info.ranges[EXECMEM_DEFAULT].pgprot = PAGE_KERNEL;
>  
> +	return &execmem_info;
>  }

I'm amazed by the weird and inconsistent breakup of initializations.

What exactly is wrong with something like:

static struct execmem_info execmem_info __ro_after_init;

struct execmem_info __init *execmem_arch_setup(void)
{
	execmem_info = (struct execmem_info){
		.ranges = {
			[EXECMEM_DEFAULT] = {
				.start	= MODULES_VADDR,
				.end	= MODULES_END,
				.pgprot	= PAGE_KERNEL,
				.alignment = 1,
			},
		},
	};
	return &execmem_info;
}