Re: [kvm-unit-tests PATCH v2 06/16] x86/run_in_user: Change type of code label

[Sean Christopherson <seanjc@google.com>]

On Thu, Apr 13, 2023, Mathias Krause wrote:
> Use an array type to refer to the code label 'ret_to_kernel'.

Why?  Taking the address of a label when setting what is effectively the target
of a branch seems more intuitive than pointing at an array (that's not an array).

> No functional change.
> 
> Signed-off-by: Mathias Krause <minipli@grsecurity.net>
> ---
>  lib/x86/usermode.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/x86/usermode.c b/lib/x86/usermode.c
> index e22fb8f0132b..b976123ca753 100644
> --- a/lib/x86/usermode.c
> +++ b/lib/x86/usermode.c
> @@ -35,12 +35,12 @@ uint64_t run_in_user(usermode_func func, unsigned int fault_vector,
>  		uint64_t arg1, uint64_t arg2, uint64_t arg3,
>  		uint64_t arg4, bool *raised_vector)
>  {
> -	extern char ret_to_kernel;
> +	extern char ret_to_kernel[];
>  	uint64_t rax = 0;
>  	static unsigned char user_stack[USERMODE_STACK_SIZE];
>  
>  	*raised_vector = 0;
> -	set_idt_entry(RET_TO_KERNEL_IRQ, &ret_to_kernel, 3);
> +	set_idt_entry(RET_TO_KERNEL_IRQ, ret_to_kernel, 3);
>  	handle_exception(fault_vector,
>  			restore_exec_to_jmpbuf_exception_handler);
>  
> -- 
> 2.39.2
>