Re: [patch v2 05/10] s390: Add PSW restart shutdown trigger

[Vivek Goyal <vgoyal@redhat.com>]

On Wed, Jul 27, 2011 at 02:55:09PM +0200, Michael Holzheu wrote:
> 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.

i know nothing about s390 but this sounds like a independent
functionality? I mean defining a restart trigger and associated actions
could be done even in current framework without kdump. IIUC, additional
kdump series only adds the ability to use kdump for second kernel instead
of using dump tools in case of "dump" or "dump_reipl" ?

If yes, then this patch probably does not have to be part of this series
and pushed in independetly?

Thanks
Vivek

> 
> 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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