[V3 09/11] tools: Add atomic_test_and_set_bit()

Peter Gonda
2022-08-10T15:21:52Z

atomic_test_and_set_bit() allows for atomic bitmap usage from KVM
selftests.

Signed-off-by: Peter Gonda <pgonda@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
---
tools/arch/x86/include/asm/atomic.h | 7 +++++++
tools/include/asm-generic/atomic-gcc.h | 15 +++++++++++++++
2 files changed, 22 insertions(+)

diff --git a/tools/arch/x86/include/asm/atomic.h b/tools/arch/x86/include/asm/atomic.h
index 1f5e26aae9fc..01cc27ec4520 100644
--- a/tools/arch/x86/include/asm/atomic.h
+++ b/tools/arch/x86/include/asm/atomic.h
@@ -8,6 +8,7 @@

#define LOCK_PREFIX "\n\tlock; "

+#include <asm/asm.h>
#include <asm/cmpxchg.h>

/*
@@ -70,4 +71,10 @@ static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
return cmpxchg(&v->counter, old, new);
}

+static inline int atomic_test_and_set_bit(long nr, unsigned long *addr)
+{
+ GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(bts), *addr, "Ir", nr, "%0", "c");
+
+}
+
#endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */
diff --git a/tools/include/asm-generic/atomic-gcc.h b/tools/include/asm-generic/atomic-gcc.h
index 4c1966f7c77a..8d9b2d1768bf 100644
--- a/tools/include/asm-generic/atomic-gcc.h
+++ b/tools/include/asm-generic/atomic-gcc.h
@@ -4,6 +4,7 @@

#include <linux/compiler.h>
#include <linux/types.h>
+#include <linux/bitops.h>

/*
* Atomic operations that C can't guarantee us. Useful for
@@ -69,4 +70,18 @@ static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
return cmpxchg(&(v)->counter, oldval, newval);
}

+static inline int atomic_test_and_set_bit(long nr, unsigned long *addr)
+{
+ long old, val;
+ unsigned long mask = BIT_MASK(nr);
+
+ addr += BIT_WORD(nr);
+ val = READ_ONCE(*addr);
+ if (val & mask)
+ return 1;
+
+ old = cmpxchg(addr, val, val & mask);
+ return !!(old & mask);
+}
+
#endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */
--
2.37.1.559.g78731f0fdb-goog