Re: [PATCH 2/4] pc-bios/s390-ccw: Provide space for initial stack frame in start.S

[Cédric Le Goater]

On 6/26/23 15:21, Thomas Huth wrote:
> Providing the space of a stack frame is the duty of the caller,
> so we should reserve 160 bytes before jumping into the main function.
> Otherwise the main() function might write past the stack array.
>
> While we're at it, add a proper STACK_SIZE macro for the stack size
> instead of using magic numbers (this is also required for the following
> patch).
>
> Signed-off-by: Thomas Huth <thuth@redhat.com>


Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.

> ---
>   pc-bios/s390-ccw/start.S | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S
> index d29de09cc6..29b0a9ece0 100644
> --- a/pc-bios/s390-ccw/start.S
> +++ b/pc-bios/s390-ccw/start.S
> @@ -10,10 +10,12 @@
>    * directory.
>    */
>   
> +#define STACK_SIZE 0x8000
> +
>       .globl _start
>   _start:
>   
> -    larl    %r15,stack + 0x8000     /* Set up stack */
> +    larl    %r15,stack + STACK_SIZE - 160   /* Set up stack */
>   
>       /* clear bss */
>       larl    %r2,__bss_start