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Subject[patch v2 05/10] s390: Add PSW restart shutdown trigger
From: Michael Holzheu <holzheu@linux.vnet.ibm.com>

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>
---
arch/s390/include/asm/lowcore.h | 11 +++++++++--
arch/s390/include/asm/system.h | 1 +
arch/s390/kernel/asm-offsets.c | 1 +
arch/s390/kernel/entry.S | 28 ++++++++++++++++++++++++++++
arch/s390/kernel/entry64.S | 20 ++++++++++++++++++++
arch/s390/kernel/ipl.c | 39 ++++++++++++++++++++++++++++++++++++++-
arch/s390/kernel/setup.c | 24 +++++++++++++++++++++++-
arch/s390/kernel/smp.c | 8 ++++++++
arch/s390/mm/maccess.c | 16 ++++++++++++++++
9 files changed, 144 insertions(+), 4 deletions(-)

--- 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 */
--- 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); \
--- 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 */
--- 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
--- 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
--- 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_tr
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_ini
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");
--- 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();
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -470,6 +470,11 @@ int __cpuinit start_secondary(void *cpuv
ipi_call_unlock();
/* Switch on interrupts */
local_irq_enable();
+ __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 */
/* cpu_idle will call schedule for us */
cpu_idle();
return 0;
@@ -507,6 +512,9 @@ static int __cpuinit smp_alloc_lowcore(i
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;

#ifndef CONFIG_64BIT
if (MACHINE_HAS_IEEE) {
--- a/arch/s390/mm/maccess.c
+++ b/arch/s390/mm/maccess.c
@@ -85,3 +85,19 @@ int memcpy_real(void *dest, void *src, s
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();
+}


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