[S390] percpu: implement arch specific irqsafe_cpu_ops

Implement arch specific irqsafe_cpu ops. The arch specific ops do not
disable/enable interrupts since that is an expensive operation. Instead
we disable preemption and perform a compare and swap loop.
Since on server distros (the ones we care about) preemption is disabled
the preempt_disable()/preempt_enable() pair is a nop.
In the end this code should be faster than the generic one.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 68 insertions, 1 deletions

diff --git a/arch/s390/include/asm/cmpxchg.h b/arch/s390/include/asm/cmpxchg.h
index 7488e52efa97..81d7908416cf 100644
--- a/arch/s390/include/asm/cmpxchg.h
+++ b/arch/s390/include/asm/cmpxchg.h
@@ -167,7 +167,6 @@ static inline unsigned long __cmpxchg(void *ptr, unsigned long old,
 #ifdef CONFIG_64BIT
 #define cmpxchg64(ptr, o, n)                                            \
 ({                                                                      \
-        BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
         cmpxchg((ptr), (o), (n));                                       \
 })
 #else /* CONFIG_64BIT */
diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h
index f7ad8719d02d..5325c89a5843 100644
--- a/arch/s390/include/asm/percpu.h
+++ b/arch/s390/include/asm/percpu.h
@@ -1,6 +1,9 @@
 #ifndef __ARCH_S390_PERCPU__
 #define __ARCH_S390_PERCPU__
 
+#include <linux/preempt.h>
+#include <asm/cmpxchg.h>
+
 /*
  * s390 uses its own implementation for per cpu data, the offset of
  * the cpu local data area is cached in the cpu's lowcore memory.
@@ -16,6 +19,71 @@
 #define ARCH_NEEDS_WEAK_PER_CPU
 #endif
 
+#define arch_irqsafe_cpu_to_op(pcp, val, op)                            \
+do {                                                                    \
+        typedef typeof(pcp) pcp_op_T__;                                 \
+        pcp_op_T__ old__, new__, prev__;                                \
+        pcp_op_T__ *ptr__;                                              \
+        preempt_disable();                                              \
+        ptr__ = __this_cpu_ptr(&(pcp));                                 \
+        prev__ = *ptr__;                                                \
+        do {                                                            \
+                old__ = prev__;                                         \
+                new__ = old__ op (val);                                 \
+                switch (sizeof(*ptr__)) {                               \
+                case 8:                                                 \
+                        prev__ = cmpxchg64(ptr__, old__, new__);        \
+                        break;                                          \
+                default:                                                \
+                        prev__ = cmpxchg(ptr__, old__, new__);          \
+                }                                                       \
+        } while (prev__ != old__);                                      \
+        preempt_enable();                                               \
+} while (0)
+
+#define irqsafe_cpu_add_1(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, +)
+#define irqsafe_cpu_add_2(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, +)
+#define irqsafe_cpu_add_4(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, +)
+#define irqsafe_cpu_add_8(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, +)
+
+#define irqsafe_cpu_and_1(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, &)
+#define irqsafe_cpu_and_2(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, &)
+#define irqsafe_cpu_and_4(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, &)
+#define irqsafe_cpu_and_8(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, &)
+
+#define irqsafe_cpu_or_1(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, |)
+#define irqsafe_cpu_or_2(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, |)
+#define irqsafe_cpu_or_4(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, |)
+#define irqsafe_cpu_or_8(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, |)
+
+#define irqsafe_cpu_xor_1(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, ^)
+#define irqsafe_cpu_xor_2(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, ^)
+#define irqsafe_cpu_xor_4(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, ^)
+#define irqsafe_cpu_xor_8(pcp, val) arch_irqsafe_cpu_to_op(pcp, val, ^)
+
+#define arch_irqsafe_cpu_cmpxchg(pcp, oval, nval)                       \
+({                                                                      \
+        typedef typeof(pcp) pcp_op_T__;                                 \
+        pcp_op_T__ ret__;                                               \
+        pcp_op_T__ *ptr__;                                              \
+        preempt_disable();                                              \
+        ptr__ = __this_cpu_ptr(&(pcp));                                 \
+        switch (sizeof(*ptr__)) {                                       \
+        case 8:                                                         \
+                ret__ = cmpxchg64(ptr__, oval, nval);                   \
+                break;                                                  \
+        default:                                                        \
+                ret__ = cmpxchg(ptr__, oval, nval);                     \
+        }                                                               \
+        preempt_enable();                                               \
+        ret__;                                                          \
+})
+
+#define irqsafe_cpu_cmpxchg_1(pcp, oval, nval) arch_irqsafe_cpu_cmpxchg(pcp, oval, nval)
+#define irqsafe_cpu_cmpxchg_2(pcp, oval, nval) arch_irqsafe_cpu_cmpxchg(pcp, oval, nval)
+#define irqsafe_cpu_cmpxchg_4(pcp, oval, nval) arch_irqsafe_cpu_cmpxchg(pcp, oval, nval)
+#define irqsafe_cpu_cmpxchg_8(pcp, oval, nval) arch_irqsafe_cpu_cmpxchg(pcp, oval, nval)
+
 #include <asm-generic/percpu.h>
 
 #endif /* __ARCH_S390_PERCPU__ */