alpha: futex implementation

Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Richard Henderson <rth@twiddle.net
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 116 insertions, 4 deletions

diff --git a/arch/alpha/include/asm/barrier.h b/arch/alpha/include/asm/barrier.h
index ac78eba909bc..ce8860a0b32d 100644
--- a/arch/alpha/include/asm/barrier.h
+++ b/arch/alpha/include/asm/barrier.h
@@ -16,11 +16,13 @@ __asm__ __volatile__("wmb": : :"memory")
 __asm__ __volatile__("mb": : :"memory")
 
 #ifdef CONFIG_SMP
+#define __ASM_SMP_MB    "\tmb\n"
 #define smp_mb()        mb()
 #define smp_rmb()       rmb()
 #define smp_wmb()       wmb()
 #define smp_read_barrier_depends()      read_barrier_depends()
 #else
+#define __ASM_SMP_MB
 #define smp_mb()        barrier()
 #define smp_rmb()       barrier()
 #define smp_wmb()       barrier()
diff --git a/arch/alpha/include/asm/futex.h b/arch/alpha/include/asm/futex.h
index 6a332a9f099c..945de222ab91 100644
--- a/arch/alpha/include/asm/futex.h
+++ b/arch/alpha/include/asm/futex.h
@@ -1,6 +1,116 @@
-#ifndef _ASM_FUTEX_H
-#define _ASM_FUTEX_H
+#ifndef _ASM_ALPHA_FUTEX_H
+#define _ASM_ALPHA_FUTEX_H
 
-#include <asm-generic/futex.h>
+#ifdef __KERNEL__
 
-#endif
+#include <linux/futex.h>
+#include <linux/uaccess.h>
+#include <asm/errno.h>
+#include <asm/barrier.h>
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)      \
+        __asm__ __volatile__(                                   \
+                __ASM_SMP_MB                                    \
+        "1:     ldl_l   %0,0(%2)\n"                             \
+                insn                                            \
+        "2:     stl_c   %1,0(%2)\n"                             \
+        "       beq     %1,4f\n"                                \
+        "       mov     $31,%1\n"                               \
+        "3:     .subsection 2\n"                                \
+        "4:     br      1b\n"                                   \
+        "       .previous\n"                                    \
+        "       .section __ex_table,\"a\"\n"                    \
+        "       .long   1b-.\n"                                 \
+        "       lda     $31,3b-1b(%1)\n"                        \
+        "       .long   2b-.\n"                                 \
+        "       lda     $31,3b-2b(%1)\n"                        \
+        "       .previous\n"                                    \
+        :       "=&r" (oldval), "=&r"(ret)                      \
+        :       "r" (uaddr), "r"(oparg)                         \
+        :       "memory")
+
+static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
+{
+        int op = (encoded_op >> 28) & 7;
+        int cmp = (encoded_op >> 24) & 15;
+        int oparg = (encoded_op << 8) >> 20;
+        int cmparg = (encoded_op << 20) >> 20;
+        int oldval = 0, ret;
+        if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
+                oparg = 1 << oparg;
+
+        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+                return -EFAULT;
+
+        pagefault_disable();
+
+        switch (op) {
+        case FUTEX_OP_SET:
+                __futex_atomic_op("mov %3,%1\n", ret, oldval, uaddr, oparg);
+                break;
+        case FUTEX_OP_ADD:
+                __futex_atomic_op("addl %0,%3,%1\n", ret, oldval, uaddr, oparg);
+                break;
+        case FUTEX_OP_OR:
+                __futex_atomic_op("or %0,%3,%1\n", ret, oldval, uaddr, oparg);
+                break;
+        case FUTEX_OP_ANDN:
+                __futex_atomic_op("andnot %0,%3,%1\n", ret, oldval, uaddr, oparg);
+                break;
+        case FUTEX_OP_XOR:
+                __futex_atomic_op("xor %0,%3,%1\n", ret, oldval, uaddr, oparg);
+                break;
+        default:
+                ret = -ENOSYS;
+        }
+
+        pagefault_enable();
+
+        if (!ret) {
+                switch (cmp) {
+                case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
+                case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
+                case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
+                case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
+                case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
+                case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
+                default: ret = -ENOSYS;
+                }
+        }
+        return ret;
+}
+
+static inline int
+futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
+{
+        int prev, cmp;
+
+        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+                return -EFAULT;
+
+        __asm__ __volatile__ (
+                __ASM_SMP_MB
+        "1:     ldl_l   %0,0(%2)\n"
+        "       cmpeq   %0,%3,%1\n"
+        "       beq     %1,3f\n"
+        "       mov     %4,%1\n"
+        "2:     stl_c   %1,0(%2)\n"
+        "       beq     %1,4f\n"
+        "3:     .subsection 2\n"
+        "4:     br      1b\n"
+        "       .previous\n"
+        "       .section __ex_table,\"a\"\n"
+        "       .long   1b-.\n"
+        "       lda     $31,3b-1b(%0)\n"
+        "       .long   2b-.\n"
+        "       lda     $31,3b-2b(%0)\n"
+        "       .previous\n"
+        :       "=&r"(prev), "=&r"(cmp)
+        :       "r"(uaddr), "r"((long)oldval), "r"(newval)
+        :       "memory");
+
+        return prev;
+}
+
+#endif /* __KERNEL__ */
+#endif /* _ASM_ALPHA_FUTEX_H */