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From: Janosch Frank <frankja@linux.ibm.com>
To: pbonzini@redhat.com
Cc: kvm@vger.kernel.org, frankja@linux.vnet.ibm.com,
	david@redhat.com, thuth@redhat.com, pmorel@linux.ibm.com,
	linux-s390@vger.kernel.org, imbrenda@linux.ibm.com
Subject: [kvm-unit-tests GIT PULL 02/11] s390x: saving regs for interrupts
Date: Fri, 31 Jul 2020 11:45:58 +0200
Message-ID: <20200731094607.15204-3-frankja@linux.ibm.com> (raw)
In-Reply-To: <20200731094607.15204-1-frankja@linux.ibm.com>

From: Pierre Morel <pmorel@linux.ibm.com>

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@linux.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Thomas Huth <thuth@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <1594887809-10521-2-git-send-email-pmorel@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 s390x/cstart64.S | 41 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/s390x/cstart64.S b/s390x/cstart64.S
index e084f13..4e51150 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 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
+	/* 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 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)
+	.endr
+	/* Now that we're 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:
@@ -185,9 +222,9 @@ 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:
-- 
2.25.4


  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31  9:45 [kvm-unit-tests GIT PULL 00/11] s390x patches Janosch Frank
2020-07-31  9:45 ` [kvm-unit-tests GIT PULL 01/11] s390x/cpumodel: The missing DFP facility on TCG is expected Janosch Frank
2020-07-31  9:45 ` Janosch Frank [this message]
2020-07-31  9:45 ` [kvm-unit-tests GIT PULL 03/11] s390x: I/O interrupt registration Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 04/11] s390x: export the clock get_clock_ms() utility Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 05/11] s390x: clock and delays calculations Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 06/11] s390x: define function to wait for interrupt Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 07/11] s390x: Library resources for CSS tests Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 08/11] s390x: css: stsch, enumeration test Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 09/11] s390x: css: msch, enable test Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 10/11] s390x: css: ssch/tsch with sense and interrupt Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 11/11] s390x: fix inline asm on gcc10 Janosch Frank
2020-07-31 10:31 ` [kvm-unit-tests GIT PULL 00/11] s390x patches Paolo Bonzini
2020-07-31 11:31   ` Janosch Frank
2020-07-31 12:09     ` Thomas Huth
2020-07-31 12:31       ` Janosch Frank

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