ARC: Add llock/scond to futex backend

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

diff --git a/arch/arc/include/asm/futex.h b/arch/arc/include/asm/futex.h
index 05b5aaf..70cfe16 100644 (file)
--- a/arch/arc/include/asm/futex.h
+++ b/arch/arc/include/asm/futex.h
@@ -16,12 +16,40 @@
 #include <linux/uaccess.h>
 #include <asm/errno.h>
 
+#ifdef CONFIG_ARC_HAS_LLSC
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
+                                                       \
+       __asm__ __volatile__(                           \
+       "1:     llock   %1, [%2]                \n"     \
+               insn                            "\n"    \
+       "2:     scond   %0, [%2]                \n"     \
+       "       bnz     1b                      \n"     \
+       "       mov %0, 0                       \n"     \
+       "3:                                     \n"     \
+       "       .section .fixup,\"ax\"          \n"     \
+       "       .align  4                       \n"     \
+       "4:     mov %0, %4                      \n"     \
+       "       b   3b                          \n"     \
+       "       .previous                       \n"     \
+       "       .section __ex_table,\"a\"       \n"     \
+       "       .align  4                       \n"     \
+       "       .word   1b, 4b                  \n"     \
+       "       .word   2b, 4b                  \n"     \
+       "       .previous                       \n"     \
+                                                       \
+       : "=&r" (ret), "=&r" (oldval)                   \
+       : "r" (uaddr), "r" (oparg), "ir" (-EFAULT)      \
+       : "cc", "memory")
+
+#else  /* !CONFIG_ARC_HAS_LLSC */
+
 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
                                                        \
        __asm__ __volatile__(                           \
-       "1:     ld  %1, [%2]                    \n"     \
+       "1:     ld      %1, [%2]                \n"     \
                insn                            "\n"    \
-       "2:     st  %0, [%2]                    \n"     \
+       "2:     st      %0, [%2]                \n"     \
        "       mov %0, 0                       \n"     \
        "3:                                     \n"     \
        "       .section .fixup,\"ax\"          \n"     \
@@ -39,6 +67,8 @@
        : "r" (uaddr), "r" (oparg), "ir" (-EFAULT)      \
        : "cc", "memory")
 
+#endif
+
 static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
 {
        int op = (encoded_op >> 28) & 7;
@@ -123,11 +153,17 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
 
        pagefault_disable();
 
-       /* TBD : can use llock/scond */
        __asm__ __volatile__(
-       "1:     ld    %0, [%3]  \n"
-       "       brne  %0, %1, 3f        \n"
-       "2:     st    %2, [%3]  \n"
+#ifdef CONFIG_ARC_HAS_LLSC
+       "1:     llock   %0, [%3]                \n"
+       "       brne    %0, %1, 3f              \n"
+       "2:     scond   %2, [%3]                \n"
+       "       bnz     1b                      \n"
+#else
+       "1:     ld      %0, [%3]                \n"
+       "       brne    %0, %1, 3f              \n"
+       "2:     st      %2, [%3]                \n"
+#endif
        "3:     \n"
        "       .section .fixup,\"ax\"  \n"
        "4:     mov %0, %4      \n"