[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>

9 files changed, 146 insertions, 5 deletions

diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h
index f26280d9e88d..e85c911aabf0 100644
--- a/arch/s390/include/asm/lowcore.h
+++ b/arch/s390/include/asm/lowcore.h
@@ -18,6 +18,7 @@ void system_call(void);
 void pgm_check_handler(void);
 void mcck_int_handler(void);
 void io_int_handler(void);
+void psw_restart_int_handler(void);
 
 #ifdef CONFIG_32BIT
 
@@ -150,7 +151,10 @@ struct _lowcore {
          */
         __u32   ipib;                           /* 0x0e00 */
         __u32   ipib_checksum;                  /* 0x0e04 */
-        __u8    pad_0x0e08[0x0f00-0x0e08];      /* 0x0e08 */
+
+        /* 64 bit save area */
+        __u64   save_area_64;                   /* 0x0e08 */
+        __u8    pad_0x0e10[0x0f00-0x0e10];      /* 0x0e10 */
 
         /* Extended facility list */
         __u64   stfle_fac_list[32];             /* 0x0f00 */
@@ -286,7 +290,10 @@ struct _lowcore {
          */
         __u64   ipib;                           /* 0x0e00 */
         __u32   ipib_checksum;                  /* 0x0e08 */
-        __u8    pad_0x0e0c[0x0f00-0x0e0c];      /* 0x0e0c */
+
+        /* 64 bit save area */
+        __u64   save_area_64;                   /* 0x0e0c */
+        __u8    pad_0x0e14[0x0f00-0x0e14];      /* 0x0e14 */
 
         /* Extended facility list */
         __u64   stfle_fac_list[32];             /* 0x0f00 */
diff --git a/arch/s390/include/asm/system.h b/arch/s390/include/asm/system.h
index d382629a0172..6582f69f2389 100644
--- a/arch/s390/include/asm/system.h
+++ b/arch/s390/include/asm/system.h
@@ -113,6 +113,7 @@ extern void pfault_fini(void);
 
 extern void cmma_init(void);
 extern int memcpy_real(void *, void *, size_t);
+extern void copy_to_absolute_zero(void *dest, void *src, size_t count);
 
 #define finish_arch_switch(prev) do {                                        \
         set_fs(current->thread.mm_segment);                                  \
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 05d8f38734ec..199a537d4f36 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -142,6 +142,7 @@ int main(void)
         DEFINE(__LC_FPREGS_SAVE_AREA, offsetof(struct _lowcore, floating_pt_save_area));
         DEFINE(__LC_GPREGS_SAVE_AREA, offsetof(struct _lowcore, gpregs_save_area));
         DEFINE(__LC_CREGS_SAVE_AREA, offsetof(struct _lowcore, cregs_save_area));
+        DEFINE(__LC_SAVE_AREA_64, offsetof(struct _lowcore, save_area_64));
 #ifdef CONFIG_32BIT
         DEFINE(SAVE_AREA_BASE, offsetof(struct _lowcore, extended_save_area_addr));
 #else /* CONFIG_32BIT */
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 3eab7cfab07c..02ec8fe7d03f 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -849,6 +849,34 @@ restart_crash:
 restart_go:
 #endif
 
+#
+# PSW restart interrupt handler
+#
+ENTRY(psw_restart_int_handler)
+        st      %r15,__LC_SAVE_AREA_64(%r0)     # save r15
+        basr    %r15,0
+0:      l       %r15,.Lrestart_stack-0b(%r15)   # load restart stack
+        l       %r15,0(%r15)
+        ahi     %r15,-SP_SIZE                   # make room for pt_regs
+        stm     %r0,%r14,SP_R0(%r15)            # store gprs %r0-%r14 to stack
+        mvc     SP_R15(4,%r15),__LC_SAVE_AREA_64(%r0)# store saved %r15 to stack
+        mvc     SP_PSW(8,%r15),__LC_RST_OLD_PSW(%r0) # store restart old psw
+        xc      __SF_BACKCHAIN(4,%r15),__SF_BACKCHAIN(%r15) # set backchain to 0
+        basr    %r14,0
+1:      l       %r14,.Ldo_restart-1b(%r14)
+        basr    %r14,%r14
+
+        basr    %r14,0                          # load disabled wait PSW if
+2:      lpsw    restart_psw_crash-2b(%r14)      # do_restart returns
+        .align 4
+.Ldo_restart:
+        .long   do_restart
+.Lrestart_stack:
+        .long   restart_stack
+        .align 8
+restart_psw_crash:
+        .long   0x000a0000,0x00000000 + restart_psw_crash
+
         .section .kprobes.text, "ax"
 
 #ifdef CONFIG_CHECK_STACK
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 7a0fd426ca92..5f729d627cef 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
diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index a689070be287..059c59027ac0 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -45,11 +45,13 @@
  * - halt
  * - power off
  * - reipl
+ * - restart
  */
 #define ON_PANIC_STR            "on_panic"
 #define ON_HALT_STR             "on_halt"
 #define ON_POFF_STR             "on_poff"
 #define ON_REIPL_STR            "on_reboot"
+#define ON_RESTART_STR          "on_restart"
 
 struct shutdown_action;
 struct shutdown_trigger {
@@ -1544,17 +1546,20 @@ static char vmcmd_on_reboot[128];
 static char vmcmd_on_panic[128];
 static char vmcmd_on_halt[128];
 static char vmcmd_on_poff[128];
+static char vmcmd_on_restart[128];
 
 DEFINE_IPL_ATTR_STR_RW(vmcmd, on_reboot, "%s\n", "%s\n", vmcmd_on_reboot);
 DEFINE_IPL_ATTR_STR_RW(vmcmd, on_panic, "%s\n", "%s\n", vmcmd_on_panic);
 DEFINE_IPL_ATTR_STR_RW(vmcmd, on_halt, "%s\n", "%s\n", vmcmd_on_halt);
 DEFINE_IPL_ATTR_STR_RW(vmcmd, on_poff, "%s\n", "%s\n", vmcmd_on_poff);
+DEFINE_IPL_ATTR_STR_RW(vmcmd, on_restart, "%s\n", "%s\n", vmcmd_on_restart);
 
 static struct attribute *vmcmd_attrs[] = {
         &sys_vmcmd_on_reboot_attr.attr,
         &sys_vmcmd_on_panic_attr.attr,
         &sys_vmcmd_on_halt_attr.attr,
         &sys_vmcmd_on_poff_attr.attr,
+        &sys_vmcmd_on_restart_attr.attr,
         NULL,
 };
 
@@ -1576,6 +1581,8 @@ static void vmcmd_run(struct shutdown_trigger *trigger)
                 cmd = vmcmd_on_halt;
         else if (strcmp(trigger->name, ON_POFF_STR) == 0)
                 cmd = vmcmd_on_poff;
+        else if (strcmp(trigger->name, ON_RESTART_STR) == 0)
+                cmd = vmcmd_on_restart;
         else
                 return;
 
@@ -1707,6 +1714,34 @@ static void do_panic(void)
         stop_run(&on_panic_trigger);
 }
 
+/* on restart */
+
+static struct shutdown_trigger on_restart_trigger = {ON_RESTART_STR,
+        &reipl_action};
+
+static ssize_t on_restart_show(struct kobject *kobj,
+                               struct kobj_attribute *attr, char *page)
+{
+        return sprintf(page, "%s\n", on_restart_trigger.action->name);
+}
+
+static ssize_t on_restart_store(struct kobject *kobj,
+                                struct kobj_attribute *attr,
+                                const char *buf, size_t len)
+{
+        return set_trigger(buf, &on_restart_trigger, len);
+}
+
+static struct kobj_attribute on_restart_attr =
+        __ATTR(on_restart, 0644, on_restart_show, on_restart_store);
+
+void do_restart(void)
+{
+        smp_send_stop();
+        on_restart_trigger.action->fn(&on_restart_trigger);
+        stop_run(&on_restart_trigger);
+}
+
 /* on halt */
 
 static struct shutdown_trigger on_halt_trigger = {ON_HALT_STR, &stop_action};
@@ -1783,7 +1818,9 @@ static void __init shutdown_triggers_init(void)
         if (sysfs_create_file(&shutdown_actions_kset->kobj,
                               &on_poff_attr.attr))
                 goto fail;
-
+        if (sysfs_create_file(&shutdown_actions_kset->kobj,
+                              &on_restart_attr.attr))
+                goto fail;
         return;
 fail:
         panic("shutdown_triggers_init failed\n");
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 0c35dee10b00..18640ff0aa1a 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -346,7 +346,7 @@ setup_lowcore(void)
         lc = __alloc_bootmem_low(LC_PAGES * PAGE_SIZE, LC_PAGES * PAGE_SIZE, 0);
         lc->restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
         lc->restart_psw.addr =
-                PSW_ADDR_AMODE | (unsigned long) restart_int_handler;
+                PSW_ADDR_AMODE | (unsigned long) psw_restart_int_handler;
         if (user_mode != HOME_SPACE_MODE)
                 lc->restart_psw.mask |= PSW_ASC_HOME;
         lc->external_new_psw.mask = psw_kernel_bits;
@@ -529,6 +529,27 @@ static void __init setup_memory_end(void)
                 memory_end = memory_size;
 }
 
+void *restart_stack __attribute__((__section__(".data")));
+
+/*
+ * Setup new PSW and allocate stack for PSW restart interrupt
+ */
+static void __init setup_restart_psw(void)
+{
+        psw_t psw;
+
+        restart_stack = __alloc_bootmem(ASYNC_SIZE, ASYNC_SIZE, 0);
+        restart_stack += ASYNC_SIZE;
+
+        /*
+         * Setup restart PSW for absolute zero lowcore. This is necesary
+         * if PSW restart is done on an offline CPU that has lowcore zero
+         */
+        psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
+        psw.addr = PSW_ADDR_AMODE | (unsigned long) psw_restart_int_handler;
+        copy_to_absolute_zero(&S390_lowcore.restart_psw, &psw, sizeof(psw));
+}
+
 static void __init
 setup_memory(void)
 {
@@ -792,6 +813,7 @@ setup_arch(char **cmdline_p)
         setup_addressing_mode();
         setup_memory();
         setup_resources();
+        setup_restart_psw();
         setup_lowcore();
 
         cpu_init();
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index a6d85c0a7f20..70f4b9604575 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -468,6 +468,11 @@ int __cpuinit start_secondary(void *cpuvoid)
         ipi_call_lock();
         set_cpu_online(smp_processor_id(), true);
         ipi_call_unlock();
+        __ctl_clear_bit(0, 28); /* Disable lowcore protection */
+        S390_lowcore.restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
+        S390_lowcore.restart_psw.addr =
+                PSW_ADDR_AMODE | (unsigned long) psw_restart_int_handler;
+        __ctl_set_bit(0, 28); /* Enable lowcore protection */
         /* Switch on interrupts */
         local_irq_enable();
         /* cpu_idle will call schedule for us */
@@ -507,7 +512,11 @@ static int __cpuinit smp_alloc_lowcore(int cpu)
         memset((char *)lowcore + 512, 0, sizeof(*lowcore) - 512);
         lowcore->async_stack = async_stack + ASYNC_SIZE;
         lowcore->panic_stack = panic_stack + PAGE_SIZE;
-
+        lowcore->restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
+        lowcore->restart_psw.addr =
+                PSW_ADDR_AMODE | (unsigned long) restart_int_handler;
+        if (user_mode != HOME_SPACE_MODE)
+                lowcore->restart_psw.mask |= PSW_ASC_HOME;
 #ifndef CONFIG_64BIT
         if (MACHINE_HAS_IEEE) {
                 unsigned long save_area;
diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c
index 51e5cd9b906a..5dbbaa6e594c 100644
--- a/arch/s390/mm/maccess.c
+++ b/arch/s390/mm/maccess.c
@@ -85,3 +85,19 @@ int memcpy_real(void *dest, void *src, size_t count)
         arch_local_irq_restore(flags);
         return rc;
 }
+
+/*
+ * Copy memory to absolute zero
+ */
+void copy_to_absolute_zero(void *dest, void *src, size_t count)
+{
+        unsigned long cr0;
+
+        BUG_ON((unsigned long) dest + count >= sizeof(struct _lowcore));
+        preempt_disable();
+        __ctl_store(cr0, 0, 0);
+        __ctl_clear_bit(0, 28); /* disable lowcore protection */
+        memcpy_real(dest + store_prefix(), src, count);
+        __ctl_load(cr0, 0, 0);
+        preempt_enable();
+}