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Re: [PATCH RFC v2 3/4] pc-bios: s390x: Save io and external new PSWs bef
From: |
Janosch Frank |
Subject: |
Re: [PATCH RFC v2 3/4] pc-bios: s390x: Save io and external new PSWs before overwriting them |
Date: |
Thu, 27 Aug 2020 16:30:38 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 |
On 8/27/20 2:52 PM, Thomas Huth wrote:
> On 27/08/2020 11.31, Janosch Frank wrote:
>> Currently we always overwrite the mentioned exception new PSWs before
>> loading the enabled wait PSW. Let's save the PSW before overwriting
>> and restore it right before starting the loaded kernel.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>
>> Maybe we should rather statically allocate a lowcore so we don't dirty
>> 0x0 at all.
>>
>> ---
>> pc-bios/s390-ccw/jump2ipl.c | 3 ++
>> pc-bios/s390-ccw/start.S | 62 +++++++++++++++++++++++++++----------
>> 2 files changed, 48 insertions(+), 17 deletions(-)
>>
>> diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c
>> index 143d027bf7..a44f3ab5b3 100644
>> --- a/pc-bios/s390-ccw/jump2ipl.c
>> +++ b/pc-bios/s390-ccw/jump2ipl.c
>> @@ -13,12 +13,15 @@
>> #define KERN_IMAGE_START 0x010000UL
>> #define RESET_PSW_MASK (PSW_MASK_SHORTPSW | PSW_MASK_64)
>>
>> +extern uint64_t *psw_save_io, *psw_save_ext;
>
> I think that should be
>
> extern uint64_t psw_save_io[], psw_save_ext[];
>
> instead ... otherwise you'll end up with some funny bugs here, won't you?
What kind of bugs are you expecting?
>
>> uint64_t *reset_psw = 0, save_psw, ipl_continue;
>>
>> static void jump_to_IPL_2(void)
>> {
>> /* Restore reset PSW and io and external new PSWs */
>
> Ok, now the comment makes sense :-)
>> *reset_psw = save_psw;
>> + memcpy((void *)0x1f0, psw_save_io, 16);
>> + memcpy((void *)0x1b0, psw_save_ext, 16);
>
> Could you use &lowcore->external_new_psw and &lowcore->io_new_psw
> instead of the magic numbers?
I can, but that means that I need to declare lowcore in netmain.c as
well as including s390-arch.h
>
> Thomas
>
>
>
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