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> --- s390x/cstart64.S | 41 +++++++++++++++++++++++++++++++++++++++-- 1 file changed, 39 insertions(+), 2 deletions(-) diff --git a/s390x/cstart64.S b/s390x/cstart64.S index 9af6bb3..3c7d8a9 100644 --- a/s390x/cstart64.S +++ b/s390x/cstart64.S @@ -118,6 +118,43 @@ 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 all registers from 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 + +/* Restore the register in reverse order */ + .macro RESTORE_REGS_STACK + /* Restore fpc */ + lfpc 0(%r15) + algfi %r15, 8 + /* Restore fp register from stack: SP still where it was left */ + /* and offset to SP is a multile of reg number */ + .irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 + ld \i, \i * 8(%r15) + .endr + /* Now it is done, rewind the stack pointer by 16 double word */ + algfi %r15, 16 * 8 + /* Load the registers from stack */ + lmg %r0, %r14, 0(%r15) + /* Rewind the stack by 15 double word */ + algfi %r15, 15 * 8 + .endm + .section .text /* * load_reset calling convention: @@ -182,9 +219,9 @@ mcck_int: lpswe GEN_LC_MCCK_OLD_PSW io_int: - SAVE_REGS + SAVE_REGS_STACK brasl %r14, handle_io_int - RESTORE_REGS + RESTORE_REGS_STACK lpswe GEN_LC_IO_OLD_PSW svc_int: -- 2.25.1
