Re: [kvm-unit-tests PATCH v2 3/8] RFC: s390x: Define STACK_FRAME_INT_SIZE macro

Thomas Huth
2021-02-17T16:12:48Z

On 17/02/2021 17.08, Janosch Frank wrote:
> On 2/17/21 4:38 PM, Thomas Huth wrote:
>> On 17/02/2021 15.41, Janosch Frank wrote:
>>> Using sizeof is safer than using magic constants. However, it doesn't
>>> really fit into asm-offsets.h as it's not an offset so I'm happy to
>>> receive suggestions on where to put it.
>>>
>>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>>> ---
>>> lib/s390x/asm-offsets.c | 1 +
>>> s390x/macros.S | 4 ++--
>>> 2 files changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/lib/s390x/asm-offsets.c b/lib/s390x/asm-offsets.c
>>> index 96cb21cf..2658b59a 100644
>>> --- a/lib/s390x/asm-offsets.c
>>> +++ b/lib/s390x/asm-offsets.c
>>> @@ -86,6 +86,7 @@ int main(void)
>>> OFFSET(STACK_FRAME_INT_CRS, stack_frame_int, crs);
>>> OFFSET(STACK_FRAME_INT_GRS0, stack_frame_int, grs0);
>>> OFFSET(STACK_FRAME_INT_GRS1, stack_frame_int, grs1);
>>> + DEFINE(STACK_FRAME_INT_SIZE, sizeof(struct stack_frame_int));
>>>
>>> return 0;
>>> }
>>> diff --git a/s390x/macros.S b/s390x/macros.S
>>> index d7eeeb55..a7d62c6f 100644
>>> --- a/s390x/macros.S
>>> +++ b/s390x/macros.S
>>> @@ -43,14 +43,14 @@
>>> /* Save registers on the stack (r15), so we can have stacked interrupts. */
>>> .macro SAVE_REGS_STACK
>>> /* Allocate a full stack frame */
>>> - slgfi %r15, 32 * 8 + 4 * 8
>>> + slgfi %r15, STACK_FRAME_INT_SIZE
>>> /* Store registers r0 to r14 on the stack */
>>> stmg %r2, %r15, STACK_FRAME_INT_GRS0(%r15)
>>> stg %r0, STACK_FRAME_INT_GRS1(%r15)
>>> stg %r1, STACK_FRAME_INT_GRS1 + 8(%r15)
>>> /* Store the gr15 value before we allocated the new stack */
>>> lgr %r0, %r15
>>> - algfi %r0, 32 * 8 + 4 * 8
>>> + algfi %r0, STACK_FRAME_INT_SIZE
>>
>> Ah, well, that of course fixes the problem that I had with the previous
>> patch. I'd suggest to merge it into patch 2.
>
> That was the plan anyway, I had so much pain until I yanked out the int
> offsets in favor of the macros. :)
>
> Did you have time to read the commit message?
> I'm not completely convinced that asm-offset.c is the right place for
> the DEFINE() so I kept this patch as a discussion starter.

Yes, I read the commit message, and I'm fine with the DEFINE in that file.
But if you feel uncomfortable, maybe add a comment in front of that line?

Thomas