summaryrefslogtreecommitdiff
path: root/arch/s390
diff options
context:
space:
mode:
authorMartin Schwidefsky <schwidefsky@de.ibm.com>2017-03-24 19:00:45 +0300
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2017-04-12 09:43:33 +0300
commitb13de4b7adeb7a5e37a5aa78d5a4926c3cd4e131 (patch)
tree472c2bdb751e5529b403dd297b76ae08f25a7d9a /arch/s390
parent02c503ff237cdcd8e012a122a638295550db10a5 (diff)
downloadlinux-b13de4b7adeb7a5e37a5aa78d5a4926c3cd4e131.tar.xz
s390/spinlock: remove compare and delay instruction
The CAD instruction never worked quite as expected for the spinlock code. It has been disabled by default with git commit 61b0b01686d48220, if the "cad" kernel parameter is specified it is enabled for both user space and the spinlock code. Leave the option to enable the instruction for user space but remove it from the spinlock code. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/include/asm/setup.h6
-rw-r--r--arch/s390/kernel/early.c19
-rw-r--r--arch/s390/lib/spinlock.c33
3 files changed, 13 insertions, 45 deletions
diff --git a/arch/s390/include/asm/setup.h b/arch/s390/include/asm/setup.h
index 383bd8358a8c..cd78155b1829 100644
--- a/arch/s390/include/asm/setup.h
+++ b/arch/s390/include/asm/setup.h
@@ -29,9 +29,8 @@
#define MACHINE_FLAG_TE _BITUL(11)
#define MACHINE_FLAG_TLB_LC _BITUL(12)
#define MACHINE_FLAG_VX _BITUL(13)
-#define MACHINE_FLAG_CAD _BITUL(14)
-#define MACHINE_FLAG_NX _BITUL(15)
-#define MACHINE_FLAG_GS _BITUL(16)
+#define MACHINE_FLAG_NX _BITUL(14)
+#define MACHINE_FLAG_GS _BITUL(15)
#define LPP_MAGIC _BITUL(31)
#define LPP_PFAULT_PID_MASK _AC(0xffffffff, UL)
@@ -69,7 +68,6 @@ extern void detect_memory_memblock(void);
#define MACHINE_HAS_TE (S390_lowcore.machine_flags & MACHINE_FLAG_TE)
#define MACHINE_HAS_TLB_LC (S390_lowcore.machine_flags & MACHINE_FLAG_TLB_LC)
#define MACHINE_HAS_VX (S390_lowcore.machine_flags & MACHINE_FLAG_VX)
-#define MACHINE_HAS_CAD (S390_lowcore.machine_flags & MACHINE_FLAG_CAD)
#define MACHINE_HAS_NX (S390_lowcore.machine_flags & MACHINE_FLAG_NX)
#define MACHINE_HAS_GS (S390_lowcore.machine_flags & MACHINE_FLAG_GS)
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 251391e3f8bc..5d20182ee8ae 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -434,23 +434,16 @@ early_param("noexec", noexec_setup);
static int __init cad_setup(char *str)
{
- int val;
-
- get_option(&str, &val);
- if (val && test_facility(128))
- S390_lowcore.machine_flags |= MACHINE_FLAG_CAD;
- return 0;
-}
-early_param("cad", cad_setup);
+ bool enabled;
+ int rc;
-static int __init cad_init(void)
-{
- if (MACHINE_HAS_CAD)
+ rc = kstrtobool(str, &enabled);
+ if (!rc && enabled && test_facility(128))
/* Enable problem state CAD. */
__ctl_set_bit(2, 3);
- return 0;
+ return rc;
}
-early_initcall(cad_init);
+early_param("cad", cad_setup);
static __init void memmove_early(void *dst, const void *src, size_t n)
{
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c
index 3f4d0c69bbfe..ffb15bd4c593 100644
--- a/arch/s390/lib/spinlock.c
+++ b/arch/s390/lib/spinlock.c
@@ -17,7 +17,7 @@ int spin_retry = -1;
static int __init spin_retry_init(void)
{
if (spin_retry < 0)
- spin_retry = MACHINE_HAS_CAD ? 10 : 1000;
+ spin_retry = 1000;
return 0;
}
early_initcall(spin_retry_init);
@@ -32,11 +32,6 @@ static int __init spin_retry_setup(char *str)
}
__setup("spin_retry=", spin_retry_setup);
-static inline void compare_and_delay(int *lock, int old)
-{
- asm(".insn rsy,0xeb0000000022,%0,0,%1" : : "d" (old), "Q" (*lock));
-}
-
void arch_spin_lock_wait(arch_spinlock_t *lp)
{
int cpu = SPINLOCK_LOCKVAL;
@@ -60,8 +55,6 @@ void arch_spin_lock_wait(arch_spinlock_t *lp)
/* Loop for a while on the lock value. */
count = spin_retry;
do {
- if (MACHINE_HAS_CAD)
- compare_and_delay(&lp->lock, owner);
owner = ACCESS_ONCE(lp->lock);
} while (owner && count-- > 0);
if (!owner)
@@ -105,8 +98,6 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
/* Loop for a while on the lock value. */
count = spin_retry;
do {
- if (MACHINE_HAS_CAD)
- compare_and_delay(&lp->lock, owner);
owner = ACCESS_ONCE(lp->lock);
} while (owner && count-- > 0);
if (!owner)
@@ -135,8 +126,7 @@ int arch_spin_trylock_retry(arch_spinlock_t *lp)
if (!owner) {
if (__atomic_cmpxchg_bool(&lp->lock, 0, cpu))
return 1;
- } else if (MACHINE_HAS_CAD)
- compare_and_delay(&lp->lock, owner);
+ }
}
return 0;
}
@@ -159,11 +149,8 @@ void _raw_read_lock_wait(arch_rwlock_t *rw)
}
old = ACCESS_ONCE(rw->lock);
owner = ACCESS_ONCE(rw->owner);
- if (old < 0) {
- if (MACHINE_HAS_CAD)
- compare_and_delay(&rw->lock, old);
+ if (old < 0)
continue;
- }
if (__atomic_cmpxchg_bool(&rw->lock, old, old + 1))
return;
}
@@ -177,11 +164,8 @@ int _raw_read_trylock_retry(arch_rwlock_t *rw)
while (count-- > 0) {
old = ACCESS_ONCE(rw->lock);
- if (old < 0) {
- if (MACHINE_HAS_CAD)
- compare_and_delay(&rw->lock, old);
+ if (old < 0)
continue;
- }
if (__atomic_cmpxchg_bool(&rw->lock, old, old + 1))
return 1;
}
@@ -212,8 +196,6 @@ void _raw_write_lock_wait(arch_rwlock_t *rw, int prev)
}
if ((old & 0x7fffffff) == 0 && prev >= 0)
break;
- if (MACHINE_HAS_CAD)
- compare_and_delay(&rw->lock, old);
}
}
EXPORT_SYMBOL(_raw_write_lock_wait);
@@ -242,8 +224,6 @@ void _raw_write_lock_wait(arch_rwlock_t *rw)
smp_mb();
if ((old & 0x7fffffff) == 0 && prev >= 0)
break;
- if (MACHINE_HAS_CAD)
- compare_and_delay(&rw->lock, old);
}
}
EXPORT_SYMBOL(_raw_write_lock_wait);
@@ -257,11 +237,8 @@ int _raw_write_trylock_retry(arch_rwlock_t *rw)
while (count-- > 0) {
old = ACCESS_ONCE(rw->lock);
- if (old) {
- if (MACHINE_HAS_CAD)
- compare_and_delay(&rw->lock, old);
+ if (old)
continue;
- }
if (__atomic_cmpxchg_bool(&rw->lock, 0, 0x80000000))
return 1;
}