[Xen-devel] [PATCH v3 1/2] atomic: add atomic_and operations

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

To x86 and Arm. This performs an atomic AND operation against an
atomic_t variable with the provided mask.

Requested-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/include/asm-arm/arm32/atomic.h | 17 +++++++++++++++++
 xen/include/asm-arm/arm64/atomic.h | 14 ++++++++++++++
 xen/include/asm-x86/atomic.h       |  8 ++++++++
 3 files changed, 39 insertions(+)

diff --git a/xen/include/asm-arm/arm32/atomic.h 
b/xen/include/asm-arm/arm32/atomic.h
index c03eb684cd..4637381bcc 100644
--- a/xen/include/asm-arm/arm32/atomic.h
+++ b/xen/include/asm-arm/arm32/atomic.h
@@ -96,6 +96,23 @@ static inline int atomic_sub_return(int i, atomic_t *v)
        return result;
 }
 
+static inline void atomic_and(unsigned int m, atomic_t *v)
+{
+       unsigned long tmp;
+       int result;
+
+       prefetchw(&v->counter);
+       __asm__ __volatile__("@ atomic_and\n"
+"1:    ldrex   %0, [%3]\n"
+"      and     %0, %0, %4\n"
+"      strex   %1, %0, [%3]\n"
+"      teq     %1, #0\n"
+"      bne     1b"
+       : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter)
+       : "r" (&v->counter), "Ir" (m)
+       : "cc");
+}
+
 static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
 {
        int oldval;
diff --git a/xen/include/asm-arm/arm64/atomic.h 
b/xen/include/asm-arm/arm64/atomic.h
index bce38d4ca2..2f906f0265 100644
--- a/xen/include/asm-arm/arm64/atomic.h
+++ b/xen/include/asm-arm/arm64/atomic.h
@@ -91,6 +91,20 @@ static inline int atomic_sub_return(int i, atomic_t *v)
        return result;
 }
 
+static inline void atomic_and(unsigned int m, atomic_t *v)
+{
+       unsigned long tmp;
+       int result;
+
+       asm volatile("// atomic_and\n"
+"1:    ldxr    %w0, %2\n"
+"      and     %w0, %w0, %w3\n"
+"      stxr    %w1, %w0, %2\n"
+"      cbnz    %w1, 1b"
+       : "=&r" (result), "=&r" (tmp), "+Q" (v->counter)
+       : "Ir" (m));
+}
+
 static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
 {
        unsigned long tmp;
diff --git a/xen/include/asm-x86/atomic.h b/xen/include/asm-x86/atomic.h
index 682bcf91b1..21794bfe7b 100644
--- a/xen/include/asm-x86/atomic.h
+++ b/xen/include/asm-x86/atomic.h
@@ -224,6 +224,14 @@ static inline int atomic_add_unless(atomic_t *v, int a, 
int u)
     return c;
 }
 
+static inline void atomic_and(unsigned int m, atomic_t *v)
+{
+    asm volatile (
+        "lock; andl %1,%0"
+        : "=m" (*(volatile int *)&v->counter)
+        : "ir" (m), "m" (*(volatile int *)&v->counter) );
+}
+
 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
 
 #endif /* __ARCH_X86_ATOMIC__ */
-- 
2.25.0


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