On 2/9/21 2:49 PM, Janosch Frank wrote:
> Having two sets of macros for saving registers on exceptions makes
> maintaining harder. Also we have limited space in the lowcore to save
> stuff and by using the stack as a save area, we can stack exceptions.
>
> So let's use the SAVE/RESTORE_REGS_STACK as the default. When we also
> move the diag308 macro over we can remove the old SAVE/RESTORE_REGS
> macros.
>
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> ---
> lib/s390x/asm-offsets.c | 14 ++++++++----
> lib/s390x/asm/arch_def.h | 29 ++++++++++++++++++-----
> lib/s390x/asm/interrupt.h | 4 ++--
> lib/s390x/interrupt.c | 14 ++++++------
> s390x/cstart64.S | 19 +++++++++-------
> s390x/macros.S | 48 +++++++++++++++++++++++----------------
> 6 files changed, 82 insertions(+), 46 deletions(-)
>
> diff --git a/lib/s390x/asm-offsets.c b/lib/s390x/asm-offsets.c
> index a19f14b9..a8942395 100644
> --- a/lib/s390x/asm-offsets.c
> +++ b/lib/s390x/asm-offsets.c
> @@ -70,16 +70,22 @@ int main(void)
> OFFSET(GEN_LC_ARS_SA, lowcore, ars_sa);
> OFFSET(GEN_LC_CRS_SA, lowcore, crs_sa);
> OFFSET(GEN_LC_PGM_INT_TDB, lowcore, pgm_int_tdb);
> - OFFSET(__SF_SIE_CONTROL, stack_frame, empty1[0]);
> - OFFSET(__SF_SIE_SAVEAREA, stack_frame, empty1[1]);
> - OFFSET(__SF_SIE_REASON, stack_frame, empty1[2]);
> - OFFSET(__SF_SIE_FLAGS, stack_frame, empty1[3]);
> + OFFSET(__SF_SIE_CONTROL, stack_frame, argument_area[0]);
> + OFFSET(__SF_SIE_SAVEAREA, stack_frame, argument_area[1]);
> + OFFSET(__SF_SIE_REASON, stack_frame, argument_area[2]);
> + OFFSET(__SF_SIE_FLAGS, stack_frame, argument_area[3]);
> OFFSET(SIE_SAVEAREA_HOST_GRS, vm_save_area, host.grs[0]);
> OFFSET(SIE_SAVEAREA_HOST_FPRS, vm_save_area, host.fprs[0]);
> OFFSET(SIE_SAVEAREA_HOST_FPC, vm_save_area, host.fpc);
> OFFSET(SIE_SAVEAREA_GUEST_GRS, vm_save_area, guest.grs[0]);
> OFFSET(SIE_SAVEAREA_GUEST_FPRS, vm_save_area, guest.fprs[0]);
> OFFSET(SIE_SAVEAREA_GUEST_FPC, vm_save_area, guest.fpc);
> + OFFSET(STACK_FRAME_INT_BACKCHAIN, stack_frame_int, back_chain);
> + OFFSET(STACK_FRAME_INT_FPC, stack_frame_int, fpc);
> + OFFSET(STACK_FRAME_INT_FPRS, stack_frame_int, fprs);
> + OFFSET(STACK_FRAME_INT_CR0, stack_frame_int, cr0);
> + OFFSET(STACK_FRAME_INT_GRS0, stack_frame_int, grs0);
> + OFFSET(STACK_FRAME_INT_GRS1, stack_frame_int, grs1);
>
> return 0;
> }
> diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
> index 9c4e330a..eb6a961f 100644
> --- a/lib/s390x/asm/arch_def.h
> +++ b/lib/s390x/asm/arch_def.h
> @@ -8,13 +8,30 @@
> #ifndef _ASM_S390X_ARCH_DEF_H_
> #define _ASM_S390X_ARCH_DEF_H_
>
> -/*
> - * We currently only specify the stack frame members needed for the
> - * SIE library code.
> - */
> struct stack_frame {
> - unsigned long back_chain;
> - unsigned long empty1[5];
> + struct stack_frame *back_chain;
> + u64 reserved;
> + /* GRs 2 - 5 */
> + unsigned long argument_area[4];
> + /* GRs 6 - 15 */
> + unsigned long grs[10];
> + /* FPRs 0, 2, 4, 6 */
> + s64 fprs[4];
> +};
> +
> +struct stack_frame_int {
> + struct stack_frame *back_chain;
> + u64 reserved;
> + /*
> + * The GRs are offset compatible with struct stack_frame so we
> + * can easily fetch GR14 for backtraces.
> + */
> + u64 grs0[14];
> + u64 grs1[2];
> + u32 res;
> + u32 fpc;
> + u64 fprs[16];
> + u64 cr0;
I just realized that we need to save all CRs just as we used to with the
SAVE_REGS macro. Because if you do a diagnose308 with DAT enabled, then
you'll loose the ASCEs and the next storage access will break absolutely
everything.
> };
>
> struct psw {
> diff --git a/lib/s390x/asm/interrupt.h b/lib/s390x/asm/interrupt.h
> index 1a2e2cd8..31e4766d 100644
> --- a/lib/s390x/asm/interrupt.h
> +++ b/lib/s390x/asm/interrupt.h
> @@ -14,8 +14,8 @@
> #define EXT_IRQ_SERVICE_SIG 0x2401
>
> void register_pgm_cleanup_func(void (*f)(void));
> -void handle_pgm_int(void);
> -void handle_ext_int(void);
> +void handle_pgm_int(struct stack_frame_int *stack);
> +void handle_ext_int(struct stack_frame_int *stack);
> void handle_mcck_int(void);
> void handle_io_int(void);
> void handle_svc_int(void);
> diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c
> index 1ce36073..94a2cf9c 100644
> --- a/lib/s390x/interrupt.c
> +++ b/lib/s390x/interrupt.c
> @@ -56,7 +56,7 @@ void register_pgm_cleanup_func(void (*f)(void))
> pgm_cleanup_func = f;
> }
>
> -static void fixup_pgm_int(void)
> +static void fixup_pgm_int(struct stack_frame_int *stack)
> {
> /* If we have an error on SIE we directly move to sie_exit */
> if (lc->pgm_old_psw.addr >= (uint64_t)&sie_entry &&
> @@ -76,7 +76,7 @@ static void fixup_pgm_int(void)
> /* Handling for iep.c test case. */
> if (lc->trans_exc_id & 0x80UL && lc->trans_exc_id & 0x04UL &&
> !(lc->trans_exc_id & 0x08UL))
> - lc->pgm_old_psw.addr = lc->sw_int_grs[14];
> + lc->pgm_old_psw.addr = stack->grs0[12];
> break;
> case PGM_INT_CODE_SEGMENT_TRANSLATION:
> case PGM_INT_CODE_PAGE_TRANSLATION:
> @@ -115,7 +115,7 @@ static void fixup_pgm_int(void)
> /* suppressed/terminated/completed point already at the next address */
> }
>
> -void handle_pgm_int(void)
> +void handle_pgm_int(struct stack_frame_int *stack)
> {
> if (!pgm_int_expected) {
> /* Force sclp_busy to false, otherwise we will loop forever */
> @@ -130,10 +130,10 @@ void handle_pgm_int(void)
> if (pgm_cleanup_func)
> (*pgm_cleanup_func)();
> else
> - fixup_pgm_int();
> + fixup_pgm_int(stack);
> }
>
> -void handle_ext_int(void)
> +void handle_ext_int(struct stack_frame_int *stack)
> {
> if (!ext_int_expected &&
> lc->ext_int_code != EXT_IRQ_SERVICE_SIG) {
> @@ -143,13 +143,13 @@ void handle_ext_int(void)
> }
>
> if (lc->ext_int_code == EXT_IRQ_SERVICE_SIG) {
> - lc->sw_int_crs[0] &= ~(1UL << 9);
> + stack->cr0 &= ~(1UL << 9);
> sclp_handle_ext();
> } else {
> ext_int_expected = false;
> }
>
> - if (!(lc->sw_int_crs[0] & CR0_EXTM_MASK))
> + if (!(stack->cr0 & CR0_EXTM_MASK))
> lc->ext_old_psw.mask &= ~PSW_MASK_EXT;
> }
>
> diff --git a/s390x/cstart64.S b/s390x/cstart64.S
> index ace0c0d9..35d20293 100644
> --- a/s390x/cstart64.S
> +++ b/s390x/cstart64.S
> @@ -92,33 +92,36 @@ memsetxc:
>
> .section .text
> pgm_int:
> - SAVE_REGS
> + SAVE_REGS_STACK
> + lgr %r2, %r15
> brasl %r14, handle_pgm_int
> - RESTORE_REGS
> + RESTORE_REGS_STACK
> lpswe GEN_LC_PGM_OLD_PSW
>
> ext_int:
> - SAVE_REGS
> + SAVE_REGS_STACK
> + lgr %r2, %r15
> brasl %r14, handle_ext_int
> - RESTORE_REGS
> + RESTORE_REGS_STACK
> lpswe GEN_LC_EXT_OLD_PSW
>
> mcck_int:
> - SAVE_REGS
> + SAVE_REGS_STACK
> brasl %r14, handle_mcck_int
> - RESTORE_REGS
> + RESTORE_REGS_STACK
> lpswe 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
>
> svc_int:
> - SAVE_REGS
> + SAVE_REGS_STACK
> brasl %r14, handle_svc_int
> - RESTORE_REGS
> + RESTORE_REGS_STACK
> lpswe GEN_LC_SVC_OLD_PSW
>
> .align 8
> diff --git a/s390x/macros.S b/s390x/macros.S
> index e51a557a..1c8a0f7c 100644
> --- a/s390x/macros.S
> +++ b/s390x/macros.S
> @@ -3,9 +3,10 @@
> * s390x assembly macros
> *
> * Copyright (c) 2017 Red Hat Inc
> - * Copyright (c) 2020 IBM Corp.
> + * Copyright (c) 2020, 2021 IBM Corp.
> *
> * Authors:
> + * Janosch Frank <frankja@xxxxxxxxxxxxx>
> * Pierre Morel <pmorel@xxxxxxxxxxxxx>
> * David Hildenbrand <david@xxxxxxxxxx>
> */
> @@ -41,36 +42,45 @@
>
> /* 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
> + /* Allocate a full stack frame */
> + slgfi %r15, 32 * 8 + 4 * 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
> + stmg %r2, %r15, STACK_FRAME_INT_GRS0(%r15)
> + stg %r0, STACK_FRAME_INT_GRS1(%r15)
> + stg %r1, STACK_FRAME_INT_GRS1 + 8(%r15)
> + /* Store the gr15 value before we allocated the new stack */
> + lgr %r0, %r15
> + algfi %r0, 32 * 8 + 4 * 8
> + stg %r0, 13 * 8 + STACK_FRAME_INT_GRS0(%r15)
> + stg %r0, STACK_FRAME_INT_BACKCHAIN(%r15)
> + /*
> + * Store CR0 and load initial CR0 so AFP is active and we can
> + * access all fprs to save them.
> + */
> + stctg %c0,%c0,STACK_FRAME_INT_CR0(%r15)
> + larl %r1, initial_cr0
> + lctlg %c0, %c0, 0(%r1)
> /* 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)
> + std \i, \i * 8 + STACK_FRAME_INT_FPRS(%r15)
> .endr
> - /* Save fpc, but keep stack aligned on 64bits */
> - slgfi %r15, 8
> - stfpc 0(%r15)
> + /* Save fpc */
> + stfpc STACK_FRAME_INT_FPC(%r15)
> .endm
>
> /* Restore the register in reverse order */
> .macro RESTORE_REGS_STACK
> /* Restore fpc */
> - lfpc 0(%r15)
> - algfi %r15, 8
> + lfpc STACK_FRAME_INT_FPC(%r15)
> /* Restore fp register from stack: SP still where it was left */
> /* and offset to SP is a multiple 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)
> + ld \i, \i * 8 + STACK_FRAME_INT_FPRS(%r15)
> .endr
> - /* Now that we're done, rewind the stack pointer by 16 double word */
> - algfi %r15, 16 * 8
> + /* Load CR0 back */
> + lctlg %c0, %c0, STACK_FRAME_INT_CR0(%r15)
> /* Load the registers from stack */
> - lmg %r0, %r14, 0(%r15)
> - /* Rewind the stack by 15 double word */
> - algfi %r15, 15 * 8
> + lg %r0, STACK_FRAME_INT_GRS1(%r15)
> + lg %r1, STACK_FRAME_INT_GRS1 + 8(%r15)
> + lmg %r2, %r15, STACK_FRAME_INT_GRS0(%r15)
> .endm
>
