refactor internal atomic.h

rather than having each arch provide its own atomic.h, there is a new
shared atomic.h in src/internal which pulls arch-specific definitions
from arc/$(ARCH)/atomic_arch.h. the latter can be extremely minimal,
defining only a_cas or new ll/sc type primitives which the shared
atomic.h will use to construct everything else.

this commit avoids making heavy changes to the individual archs'
atomic implementations. definitions which are identical or
near-identical to what the new shared atomic.h would produce have been
removed, but otherwise the changes made are just hooking up the
arch-specific files to the new infrastructure. major changes to take
advantage of the new system will come in subsequent commits.

1 files changed, 168 insertions, 0 deletions

diff --git a/arch/arm/atomic_arch.h b/arch/arm/atomic_arch.h
new file mode 100644
index 00000000..5ab20a55
--- /dev/null
+++ b/arch/arm/atomic_arch.h
@@ -0,0 +1,168 @@
+#if __ARM_ARCH_7A__ || __ARM_ARCH_7R__ ||  __ARM_ARCH >= 7
+
+#define a_barrier a_barrier
+static inline void a_barrier()
+{
+	__asm__ __volatile__("dmb ish");
+}
+
+#define a_cas a_cas
+static inline int a_cas(volatile int *p, int t, int s)
+{
+	int old;
+	__asm__ __volatile__(
+		"	dmb ish\n"
+		"1:	ldrex %0,%3\n"
+		"	cmp %0,%1\n"
+		"	bne 1f\n"
+		"	strex %0,%2,%3\n"
+		"	cmp %0, #0\n"
+		"	bne 1b\n"
+		"	mov %0, %1\n"
+		"1:	dmb ish\n"
+		: "=&r"(old)
+		: "r"(t), "r"(s), "Q"(*p)
+		: "memory", "cc" );
+	return old;
+}
+
+#define a_swap a_swap
+static inline int a_swap(volatile int *x, int v)
+{
+	int old, tmp;
+	__asm__ __volatile__(
+		"	dmb ish\n"
+		"1:	ldrex %0,%3\n"
+		"	strex %1,%2,%3\n"
+		"	cmp %1, #0\n"
+		"	bne 1b\n"
+		"	dmb ish\n"
+		: "=&r"(old), "=&r"(tmp)
+		: "r"(v), "Q"(*x)
+		: "memory", "cc" );
+	return old;
+}
+
+#define a_fetch_add a_fetch_add
+static inline int a_fetch_add(volatile int *x, int v)
+{
+	int old, tmp;
+	__asm__ __volatile__(
+		"	dmb ish\n"
+		"1:	ldrex %0,%3\n"
+		"	add %0,%0,%2\n"
+		"	strex %1,%0,%3\n"
+		"	cmp %1, #0\n"
+		"	bne 1b\n"
+		"	dmb ish\n"
+		: "=&r"(old), "=&r"(tmp)
+		: "r"(v), "Q"(*x)
+		: "memory", "cc" );
+	return old-v;
+}
+
+#define a_inc a_inc
+static inline void a_inc(volatile int *x)
+{
+	int tmp, tmp2;
+	__asm__ __volatile__(
+		"	dmb ish\n"
+		"1:	ldrex %0,%2\n"
+		"	add %0,%0,#1\n"
+		"	strex %1,%0,%2\n"
+		"	cmp %1, #0\n"
+		"	bne 1b\n"
+		"	dmb ish\n"
+		: "=&r"(tmp), "=&r"(tmp2)
+		: "Q"(*x)
+		: "memory", "cc" );
+}
+
+#define a_dec a_dec
+static inline void a_dec(volatile int *x)
+{
+	int tmp, tmp2;
+	__asm__ __volatile__(
+		"	dmb ish\n"
+		"1:	ldrex %0,%2\n"
+		"	sub %0,%0,#1\n"
+		"	strex %1,%0,%2\n"
+		"	cmp %1, #0\n"
+		"	bne 1b\n"
+		"	dmb ish\n"
+		: "=&r"(tmp), "=&r"(tmp2)
+		: "Q"(*x)
+		: "memory", "cc" );
+}
+
+#define a_and a_and
+static inline void a_and(volatile int *x, int v)
+{
+	int tmp, tmp2;
+	__asm__ __volatile__(
+		"	dmb ish\n"
+		"1:	ldrex %0,%3\n"
+		"	and %0,%0,%2\n"
+		"	strex %1,%0,%3\n"
+		"	cmp %1, #0\n"
+		"	bne 1b\n"
+		"	dmb ish\n"
+		: "=&r"(tmp), "=&r"(tmp2)
+		: "r"(v), "Q"(*x)
+		: "memory", "cc" );
+}
+
+#define a_or a_or
+static inline void a_or(volatile int *x, int v)
+{
+	int tmp, tmp2;
+	__asm__ __volatile__(
+		"	dmb ish\n"
+		"1:	ldrex %0,%3\n"
+		"	orr %0,%0,%2\n"
+		"	strex %1,%0,%3\n"
+		"	cmp %1, #0\n"
+		"	bne 1b\n"
+		"	dmb ish\n"
+		: "=&r"(tmp), "=&r"(tmp2)
+		: "r"(v), "Q"(*x)
+		: "memory", "cc" );
+}
+
+#define a_store a_store
+static inline void a_store(volatile int *p, int x)
+{
+	__asm__ __volatile__(
+		"	dmb ish\n"
+		"	str %1,%0\n"
+		"	dmb ish\n"
+		: "=m"(*p)
+		: "r"(x)
+		: "memory", "cc" );
+}
+
+#else
+
+int __a_cas(int, int, volatile int *) __attribute__((__visibility__("hidden")));
+#define __k_cas __a_cas
+
+#define a_barrier a_barrier
+static inline void a_barrier()
+{
+	__asm__ __volatile__("bl __a_barrier"
+		: : : "memory", "cc", "ip", "lr" );
+}
+
+#define a_cas a_cas
+static inline int a_cas(volatile int *p, int t, int s)
+{
+	int old;
+	for (;;) {
+		if (!__k_cas(t, s, p))
+			return t;
+		if ((old=*p) != t)
+			return old;
+	}
+}
+
+#endif