| Message ID | 20220331125515.1941-1-frankja@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [kvm-unit-tests] s390x: snippets: c: Load initial cr0 | expand |
On Thu, 31 Mar 2022 12:55:15 +0000 Janosch Frank <frankja@linux.ibm.com> wrote: > As soon as we use C we need to set the AFP bit in cr0 so we can use > all fprs. > seems like a good idea > Signed-off-by: Janosch Frank <frankja@linux.ibm.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> > --- > s390x/snippets/c/cstart.S | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/s390x/snippets/c/cstart.S b/s390x/snippets/c/cstart.S > index aaa5380c..a7d4cd42 100644 > --- a/s390x/snippets/c/cstart.S > +++ b/s390x/snippets/c/cstart.S > @@ -12,6 +12,8 @@ > .section .init > .globl start > start: > + larl %r1, initial_cr0 > + lctlg %c0, %c0, 0(%r1) > /* XOR all registers with themselves to clear them fully. */ > .irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 > xgr \i,\i > @@ -34,3 +36,7 @@ exit: > /* For now let's only use cpu 0 in snippets so this will always work. */ > xgr %r0, %r0 > sigp %r2, %r0, SIGP_STOP > + > +initial_cr0: > + /* enable AFP-register control, so FP regs (+BFP instr) can be used */ > + .quad 0x0000000000040000
diff --git a/s390x/snippets/c/cstart.S b/s390x/snippets/c/cstart.S index aaa5380c..a7d4cd42 100644 --- a/s390x/snippets/c/cstart.S +++ b/s390x/snippets/c/cstart.S @@ -12,6 +12,8 @@ .section .init .globl start start: + larl %r1, initial_cr0 + lctlg %c0, %c0, 0(%r1) /* XOR all registers with themselves to clear them fully. */ .irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 xgr \i,\i @@ -34,3 +36,7 @@ exit: /* For now let's only use cpu 0 in snippets so this will always work. */ xgr %r0, %r0 sigp %r2, %r0, SIGP_STOP + +initial_cr0: + /* enable AFP-register control, so FP regs (+BFP instr) can be used */ + .quad 0x0000000000040000
As soon as we use C we need to set the AFP bit in cr0 so we can use all fprs. Signed-off-by: Janosch Frank <frankja@linux.ibm.com> --- s390x/snippets/c/cstart.S | 6 ++++++ 1 file changed, 6 insertions(+)