[S390] Add PSW restart shutdown trigger

With this patch a new S390 shutdown trigger "restart" is added. If under
z/VM "systerm restart" is entered or under the HMC the "PSW restart" button
is pressed, the PSW located at 0 (31 bit) or 0x1a0 (64 bit) bit is loaded.
Now we execute do_restart() that processes the restart action that is
defined under /sys/firmware/shutdown_actions/on_restart. Currently the
following actions are possible: reipl (default), stop, vmcmd, dump, and
dump_reipl.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 7a0fd426ca9..5f729d627ce 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -865,6 +865,26 @@ restart_crash:
 restart_go:
 #endif
 
+#
+# PSW restart interrupt handler
+#
+ENTRY(psw_restart_int_handler)
+        stg     %r15,__LC_SAVE_AREA_64(%r0)     # save r15
+        larl    %r15,restart_stack              # load restart stack
+        lg      %r15,0(%r15)
+        aghi    %r15,-SP_SIZE                   # make room for pt_regs
+        stmg    %r0,%r14,SP_R0(%r15)            # store gprs %r0-%r14 to stack
+        mvc     SP_R15(8,%r15),__LC_SAVE_AREA_64(%r0)# store saved %r15 to stack
+        mvc     SP_PSW(16,%r15),__LC_RST_OLD_PSW(%r0)# store restart old psw
+        xc      __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15) # set backchain to 0
+        brasl   %r14,do_restart
+
+        larl    %r14,restart_psw_crash          # load disabled wait PSW if
+        lpswe   0(%r14)                         # do_restart returns
+        .align 8
+restart_psw_crash:
+        .quad   0x0002000080000000,0x0000000000000000 + restart_psw_crash
+
         .section .kprobes.text, "ax"
 
 #ifdef CONFIG_CHECK_STACK