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s390/nmi: allocation of the extended save area

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The machine check extended save area is needed to store the vector
registers and the guarded storage control block when a CPU is
interrupted by a machine check.

Move the slab cache allocation of the full save area to nmi.c,
for early boot use a static __initdata block.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2017-10-12 13:24:47 +02:00
parent cc65450c83
commit 6c81511ca1
4 changed files with 99 additions and 47 deletions
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82
arch/s390/kernel/nmi.c
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@@ -12,7 +12,9 @@
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/hardirq.h>
#include <linux/log2.h>
#include <linux/kprobes.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/module.h>
#include <linux/sched/signal.h>
@@ -38,6 +40,86 @@ struct mcck_struct {
};
static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
static struct kmem_cache *mcesa_cache;
static unsigned long mcesa_origin_lc;
static inline int nmi_needs_mcesa(void)
{
return MACHINE_HAS_VX || MACHINE_HAS_GS;
}
static inline unsigned long nmi_get_mcesa_size(void)
{
if (MACHINE_HAS_GS)
return MCESA_MAX_SIZE;
return MCESA_MIN_SIZE;
}
/*
* The initial machine check extended save area for the boot CPU.
* It will be replaced by nmi_init() with an allocated structure.
* The structure is required for machine check happening early in
* the boot process.
*/
static struct mcesa boot_mcesa __initdata __aligned(MCESA_MAX_SIZE);
void __init nmi_alloc_boot_cpu(struct lowcore *lc)
{
if (!nmi_needs_mcesa())
return;
lc->mcesad = (unsigned long) &boot_mcesa;
if (MACHINE_HAS_GS)
lc->mcesad |= ilog2(MCESA_MAX_SIZE);
}
static int __init nmi_init(void)
{
unsigned long origin, cr0, size;
if (!nmi_needs_mcesa())
return 0;
size = nmi_get_mcesa_size();
if (size > MCESA_MIN_SIZE)
mcesa_origin_lc = ilog2(size);
/* create slab cache for the machine-check-extended-save-areas */
mcesa_cache = kmem_cache_create("nmi_save_areas", size, size, 0, NULL);
if (!mcesa_cache)
panic("Couldn't create nmi save area cache");
origin = (unsigned long) kmem_cache_alloc(mcesa_cache, GFP_KERNEL);
if (!origin)
panic("Couldn't allocate nmi save area");
/* The pointer is stored with mcesa_bits ORed in */
kmemleak_not_leak((void *) origin);
__ctl_store(cr0, 0, 0);
__ctl_clear_bit(0, 28); /* disable lowcore protection */
/* Replace boot_mcesa on the boot CPU */
S390_lowcore.mcesad = origin | mcesa_origin_lc;
__ctl_load(cr0, 0, 0);
return 0;
}
early_initcall(nmi_init);
int nmi_alloc_per_cpu(struct lowcore *lc)
{
unsigned long origin;
if (!nmi_needs_mcesa())
return 0;
origin = (unsigned long) kmem_cache_alloc(mcesa_cache, GFP_KERNEL);
if (!origin)
return -ENOMEM;
/* The pointer is stored with mcesa_bits ORed in */
kmemleak_not_leak((void *) origin);
lc->mcesad = origin | mcesa_origin_lc;
return 0;
}
void nmi_free_per_cpu(struct lowcore *lc)
{
if (!nmi_needs_mcesa())
return;
kmem_cache_free(mcesa_cache, (void *)(lc->mcesad & MCESA_ORIGIN_MASK));
}
static notrace void s390_handle_damage(void)
{