On 08/06/2020 10.12, Pierre Morel wrote: > If we use multiple source of interrupts, for example, using SCLP > console to print information while using I/O interrupts, we need > to have a re-entrant register saving interruption handling. > > Instead of saving at a static memory address, let's save the base > registers, the floating point registers and the floating point > control register on the stack in case of I/O interrupts > > Note that we keep the static register saving to recover from the > RESET tests. > > Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx> > Acked-by: Janosch Frank <frankja@xxxxxxxxxxxxx> > --- > s390x/cstart64.S | 41 +++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 39 insertions(+), 2 deletions(-) > > diff --git a/s390x/cstart64.S b/s390x/cstart64.S > index b50c42c..a9d8223 100644 > --- a/s390x/cstart64.S > +++ b/s390x/cstart64.S > @@ -119,6 +119,43 @@ memsetxc: > lmg %r0, %r15, GEN_LC_SW_INT_GRS > .endm > > +/* Save registers on the stack (r15), so we can have stacked interrupts. */ > + .macro SAVE_REGS_STACK > + /* Allocate a stack frame for 15 general registers */ > + slgfi %r15, 15 * 8 > + /* Store registers r0 to r14 on the stack */ > + stmg %r0, %r14, 0(%r15) > + /* Allocate a stack frame for 16 floating point registers */ > + /* The size of a FP register is the size of an double word */ > + slgfi %r15, 16 * 8 > + /* Save fp register on stack: offset to SP is multiple of reg number */ > + .irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 > + std \i, \i * 8(%r15) > + .endr > + /* Save fpc, but keep stack aligned on 64bits */ > + slgfi %r15, 8 > + efpc %r0 > + stg %r0, 0(%r15) > + .endm I wonder whether it would be sufficient to only save the registers here that are "volatile" according to the ELF ABI? ... that would save quite some space on the stack, I think... OTOH, the old code was also saving all registers, so maybe that's something for a separate patch later... Acked-by: Thomas Huth <thuth@xxxxxxxxxx>
