On 15.07.20 16:08, Janosch Frank wrote:
> Normally they don't need to be set up before waiting for an interrupt
> but are set up on boot. The BIOS however might overwrite the lowcore
> (and hence the PSWs) when loading a blob into memory and therefore
> needs to set up those PSWs more often.
Now when I read the new comment this actually inidicates a bug.
When do we restore the original content? If the loaded program
does have interrupt handlers in the original image and relies on that
then we are broken, no?
>
> Signed-off-by: Janosch Frank <fran...@linux.ibm.com>
> ---
> pc-bios/s390-ccw/start.S | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S
> index 01c4c21b26..b0fcb918cc 100644
> --- a/pc-bios/s390-ccw/start.S
> +++ b/pc-bios/s390-ccw/start.S
> @@ -64,7 +64,10 @@ consume_sclp_int:
> stctg %c0,%c0,0(%r15)
> oi 6(%r15),0x2
> lctlg %c0,%c0,0(%r15)
> - /* prepare external call handler */
> + /*
> + * Prepare external new PSW as it might have been overwritten
> + * by a loaded blob
> + */
> larl %r1, external_new_code
> stg %r1, 0x1b8
> larl %r1, external_new_mask
> @@ -84,7 +87,10 @@ consume_io_int:
> stctg %c6,%c6,0(%r15)
> oi 4(%r15), 0xff
> lctlg %c6,%c6,0(%r15)
> - /* prepare i/o call handler */
> + /*
> + * Prepare i/o new PSW as it might have been overwritten
> + * by a loaded blob
> + */
> larl %r1, io_new_code
> stg %r1, 0x1f8
> larl %r1, io_new_mask
>
