Commit fa7c0043 authored by Michael Holzheu's avatar Michael Holzheu Committed by Martin Schwidefsky
Browse files

s390/kdump: Use real mode for PSW restart and kexec 



Currently the PSW restart handler and kexec are executed in real
mode with DAT=off. For kexec/kdump the function setup_regs() is
called that uses the per-cpu variable "crash_notes". Because
there are situations when the per-cpu implementation uses vmalloc
memory, calling setup_regs() in real mode can cause a program
check interrupt.

To fix that problem this patch changes the following:

* Ensure that diag308_reset() does not change PSW bits to real mode
* Enable DAT in __do_restart() after we switched to an online CPU
* Enable DAT in __machine_kexec() after we switched to the IPL CPU
* Call setup_regs() before we switch to real mode and call purgatory

Reviewed-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarMichael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent a9fbf1a5

arch/s390/kernel/base.S

+12 −0
Original line number Diff line number Diff line
@@ -88,6 +88,9 @@ ENTRY(diag308_reset) 
	stctg	%c0,%c15,0(%r4)

	larl	%r4,.Lfpctl		# Floating point control register

	stfpc	0(%r4)

	larl	%r4,.Lcontinue_psw	# Save PSW flags

	epsw	%r2,%r3

	stm	%r2,%r3,0(%r4)

	larl	%r4,.Lrestart_psw	# Setup restart PSW at absolute 0

	lghi	%r3,0

	lg	%r4,0(%r4)		# Save PSW
@@ -103,11 +106,20 @@ ENTRY(diag308_reset) 
	lctlg	%c0,%c15,0(%r4)

	larl	%r4,.Lfpctl		# Restore floating point ctl register

	lfpc	0(%r4)

	larl	%r4,.Lcontinue_psw	# Restore PSW flags

	lpswe	0(%r4)

.Lcontinue:

	br	%r14

.align 16

.Lrestart_psw:

	.long	0x00080000,0x80000000 + .Lrestart_part2



	.section .data..nosave,"aw",@progbits

.align 8

.Lcontinue_psw:

	.quad	0,.Lcontinue

	.previous



	.section .bss

.align 8

.Lctlregs:

arch/s390/kernel/ipl.c

+1 −0
Original line number Diff line number Diff line
@@ -1750,6 +1750,7 @@ static struct kobj_attribute on_restart_attr = 


static void __do_restart(void *ignore)

{

	__arch_local_irq_stosm(0x04); /* enable DAT */

	smp_send_stop();

#ifdef CONFIG_CRASH_DUMP

	crash_kexec(NULL);

arch/s390/kernel/machine_kexec.c

+2 −1
Original line number Diff line number Diff line
@@ -80,8 +80,8 @@ static void __do_machine_kdump(void *image) 
#ifdef CONFIG_CRASH_DUMP

	int (*start_kdump)(int) = (void *)((struct kimage *) image)->start;



	__load_psw_mask(PSW_MASK_BASE | PSW_DEFAULT_KEY | PSW_MASK_EA | PSW_MASK_BA);

	setup_regs();

	__load_psw_mask(PSW_MASK_BASE | PSW_DEFAULT_KEY | PSW_MASK_EA | PSW_MASK_BA);

	start_kdump(1);

#endif

}
@@ -214,6 +214,7 @@ static void __machine_kexec(void *data) 
{

	struct kimage *image = data;



	__arch_local_irq_stosm(0x04); /* enable DAT */

	pfault_fini();

	tracing_off();

	debug_locks_off();

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