[kvm-unit-tests PATCH v2 4/8] s390x: Introduce and use CALL_INT_HANDLER macro

Janosch Frank
2021-02-17T14:43:24Z

The ELF ABI dictates that we need to allocate 160 bytes of stack space
for the C functions we're calling. Since we would need to do that for
every interruption handler which, combined with the new stack argument
being saved in GR2, makes cstart64.S look a bit messy.

So let's introduce the CALL_INT_HANDLER macro that handles all of
that, calls the C interrupt handler and handles cleanup afterwards.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
s390x/cstart64.S | 28 +++++-----------------------
s390x/macros.S | 17 +++++++++++++++++
2 files changed, 22 insertions(+), 23 deletions(-)

diff --git a/s390x/cstart64.S b/s390x/cstart64.S
index 35d20293..666a9567 100644
--- a/s390x/cstart64.S
+++ b/s390x/cstart64.S
@@ -92,37 +92,19 @@ memsetxc:

.section .text
pgm_int:
- SAVE_REGS_STACK
- lgr %r2, %r15
- brasl %r14, handle_pgm_int
- RESTORE_REGS_STACK
- lpswe GEN_LC_PGM_OLD_PSW
+ CALL_INT_HANDLER handle_pgm_int, GEN_LC_PGM_OLD_PSW

ext_int:
- SAVE_REGS_STACK
- lgr %r2, %r15
- brasl %r14, handle_ext_int
- RESTORE_REGS_STACK
- lpswe GEN_LC_EXT_OLD_PSW
+ CALL_INT_HANDLER handle_ext_int, GEN_LC_EXT_OLD_PSW

mcck_int:
- SAVE_REGS_STACK
- brasl %r14, handle_mcck_int
- RESTORE_REGS_STACK
- lpswe GEN_LC_MCCK_OLD_PSW
+ CALL_INT_HANDLER handle_mcck_int, GEN_LC_MCCK_OLD_PSW

io_int:
- SAVE_REGS_STACK
- lgr %r2, %r15
- brasl %r14, handle_io_int
- RESTORE_REGS_STACK
- lpswe GEN_LC_IO_OLD_PSW
+ CALL_INT_HANDLER handle_io_int, GEN_LC_IO_OLD_PSW

svc_int:
- SAVE_REGS_STACK
- brasl %r14, handle_svc_int
- RESTORE_REGS_STACK
- lpswe GEN_LC_SVC_OLD_PSW
+ CALL_INT_HANDLER handle_svc_int, GEN_LC_SVC_OLD_PSW

.align 8
initial_psw:
diff --git a/s390x/macros.S b/s390x/macros.S
index a7d62c6f..212a3823 100644
--- a/s390x/macros.S
+++ b/s390x/macros.S
@@ -11,6 +11,23 @@
* David Hildenbrand <david@redhat.com>
*/
#include <asm/asm-offsets.h>
+/*
+ * Exception handler macro that saves registers on the stack,
+ * allocates stack space and calls the C handler function. Afterwards
+ * we re-load the registers and load the old PSW.
+ */
+ .macro CALL_INT_HANDLER c_func, old_psw
+ SAVE_REGS_STACK
+ /* Save the stack address in GR2 which is the first function argument */
+ lgr %r2, %r15
+ /* Allocate stack pace for called C function, as specified in s390 ELF ABI */
+ slgfi %r15, 160
+ brasl %r14, \c_func
+ algfi %r15, 160
+ RESTORE_REGS_STACK
+ lpswe \old_psw
+ .endm
+
.macro SAVE_REGS
/* save grs 0-15 */
stmg %r0, %r15, GEN_LC_SW_INT_GRS
--
2.25.1