[kvm-unit-tests PATCH v5 01/10] s390x: saving regs for interrupts

Pierre Morel
2020-02-20T12:01:15Z

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 and the floating point registers on the stack.

Note that we keep the static register saving to recover from the
RESET tests.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
s390x/cstart64.S | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/s390x/cstart64.S b/s390x/cstart64.S
index 9af6bb3..45da523 100644
--- a/s390x/cstart64.S
+++ b/s390x/cstart64.S
@@ -118,6 +118,25 @@ memsetxc:
lmg %r0, %r15, GEN_LC_SW_INT_GRS
.endm

+/* Save registers on the stack, so we can have stacked interrupts. */
+ .macro SAVE_IRQ_REGS
+ slgfi %r15, 15 * 8
+ stmg %r0, %r14, 0(%r15)
+ slgfi %r15, 16 * 8
+ .irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+ std \i, \i * 8(%r15)
+ .endr
+ .endm
+
+ .macro RESTORE_IRQ_REGS
+ .irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+ ld \i, \i * 8(%r15)
+ .endr
+ algfi %r15, 16 * 8
+ lmg %r0, %r14, 0(%r15)
+ algfi %r15, 15 * 8
+ .endm
+
.section .text
/*
* load_reset calling convention:
@@ -182,9 +201,9 @@ mcck_int:
lpswe GEN_LC_MCCK_OLD_PSW

io_int:
- SAVE_REGS
+ SAVE_IRQ_REGS
brasl %r14, handle_io_int
- RESTORE_REGS
+ RESTORE_IRQ_REGS
lpswe GEN_LC_IO_OLD_PSW

svc_int:
--
2.17.0