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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: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Michael Holzheu 2012-05-21 11:30:30 +02:00 committed by Martin Schwidefsky
parent a9fbf1a538
commit fa7c004342
3 changed files with 15 additions and 1 deletions
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12
arch/s390/kernel/base.S
View File

@ -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:

1
arch/s390/kernel/ipl.c
View File

@ -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);

3
arch/s390/kernel/machine_kexec.c
View File

@ -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();