From: David Woodhouse <dwmw2@infradead.org>
Date: Tue, 5 Sep 2006 04:53:14 +0000 (-0700)
Subject: [POWERPC] Implement PowerPC futex_atomic_cmpxchg_inatomic().
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=69588298188b40ed7f75c98a6fd328d82f23ca21;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git

[POWERPC] Implement PowerPC futex_atomic_cmpxchg_inatomic().

The sys_[gs]et_robust_list() syscalls were wired up on PowerPC but
didn't work correctly because futex_atomic_cmpxchg_inatomic() wasn't
implemented.  Implement it, based on __cmpxchg_u32().

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
---

diff --git a/include/asm-powerpc/futex.h b/include/asm-powerpc/futex.h
index f1b3c00bc1c..936422e5489 100644
--- a/include/asm-powerpc/futex.h
+++ b/include/asm-powerpc/futex.h
@@ -84,7 +84,33 @@ static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
 static inline int
 futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
 {
-	return -ENOSYS;
+	int prev;
+
+	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+		return -EFAULT;
+
+        __asm__ __volatile__ (
+        LWSYNC_ON_SMP
+"1:     lwarx   %0,0,%2         # futex_atomic_cmpxchg_inatomic\n\
+        cmpw    0,%0,%3\n\
+        bne-    3f\n"
+        PPC405_ERR77(0,%2)
+"2:     stwcx.  %4,0,%2\n\
+        bne-    1b\n"
+        ISYNC_ON_SMP
+"3:	.section .fixup,\"ax\"\n\
+4:	li	%0,%5\n\
+	b	3b\n\
+	.previous\n\
+	.section __ex_table,\"a\"\n\
+	.align 3\n\
+	" PPC_LONG "1b,4b,2b,4b\n\
+	.previous" \
+        : "=&r" (prev), "+m" (*uaddr)
+        : "r" (uaddr), "r" (oldval), "r" (newval), "i" (-EFAULT)
+        : "cc", "memory");
+
+        return prev;
 }
 
 #endif /* __KERNEL__ */