Subject: Re: [PATCH 12/14] x86: remove address space overrides using set_fs()

From: Al Viro <[email-masked]>
Date: Fri, 4 Sep 2020 03:55:10 +0100

On Thu, Sep 03, 2020 at 04:22:40PM +0200, Christoph Hellwig wrote:

> diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S
> index c8a85b512796e1..94f7be4971ed04 100644
> --- a/arch/x86/lib/getuser.S
> +++ b/arch/x86/lib/getuser.S
> @@ -35,10 +35,19 @@
>  #include <asm/smap.h>
>  #include <asm/export.h>
>  
> +#ifdef CONFIG_X86_5LEVEL
> +#define LOAD_TASK_SIZE_MINUS_N(n) \
> +	ALTERNATIVE "mov $((1 << 47) - 4096 - (n)),%rdx", \
> +		    "mov $((1 << 56) - 4096 - (n)),%rdx", X86_FEATURE_LA57
> +#else
> +#define LOAD_TASK_SIZE_MINUS_N(n) \
> +	mov $(TASK_SIZE_MAX - (n)),%_ASM_DX
> +#endif

Wait a sec... how is that supposed to build with X86_5LEVEL?  Do you mean

#define LOAD_TASK_SIZE_MINUS_N(n) \
	ALTERNATIVE __stringify(mov $((1 << 47) - 4096 - (n)),%rdx), \
		    __stringify(mov $((1 << 56) - 4096 - (n)),%rdx), X86_FEATURE_LA57

there?