From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/x86/include/asm/futex.h | 117 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100644 arch/x86/include/asm/futex.h

(limited to 'arch/x86/include/asm/futex.h')

diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h
new file mode 100644
index 000000000..b4c1f5453
--- /dev/null
+++ b/arch/x86/include/asm/futex.h
@@ -0,0 +1,117 @@
+#ifndef _ASM_X86_FUTEX_H
+#define _ASM_X86_FUTEX_H
+
+#ifdef __KERNEL__
+
+#include <linux/futex.h>
+#include <linux/uaccess.h>
+
+#include <asm/asm.h>
+#include <asm/errno.h>
+#include <asm/processor.h>
+#include <asm/smap.h>
+
+#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)	\
+	asm volatile("\t" ASM_STAC "\n"				\
+		     "1:\t" insn "\n"				\
+		     "2:\t" ASM_CLAC "\n"			\
+		     "\t.section .fixup,\"ax\"\n"		\
+		     "3:\tmov\t%3, %1\n"			\
+		     "\tjmp\t2b\n"				\
+		     "\t.previous\n"				\
+		     _ASM_EXTABLE(1b, 3b)			\
+		     : "=r" (oldval), "=r" (ret), "+m" (*uaddr)	\
+		     : "i" (-EFAULT), "0" (oparg), "1" (0))
+
+#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)	\
+	asm volatile("\t" ASM_STAC "\n"				\
+		     "1:\tmovl	%2, %0\n"			\
+		     "\tmovl\t%0, %3\n"				\
+		     "\t" insn "\n"				\
+		     "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\
+		     "\tjnz\t1b\n"				\
+		     "3:\t" ASM_CLAC "\n"			\
+		     "\t.section .fixup,\"ax\"\n"		\
+		     "4:\tmov\t%5, %1\n"			\
+		     "\tjmp\t3b\n"				\
+		     "\t.previous\n"				\
+		     _ASM_EXTABLE(1b, 4b)			\
+		     _ASM_EXTABLE(2b, 4b)			\
+		     : "=&a" (oldval), "=&r" (ret),		\
+		       "+m" (*uaddr), "=&r" (tem)		\
+		     : "r" (oparg), "i" (-EFAULT), "1" (0))
+
+static inline int futex_atomic_op_inuser(int encoded_op, u32 __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, tem;
+
+	if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
+		oparg = 1 << oparg;
+
+	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+		return -EFAULT;
+
+	pagefault_disable();
+
+	switch (op) {
+	case FUTEX_OP_SET:
+		__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
+		break;
+	case FUTEX_OP_ADD:
+		__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
+				   uaddr, oparg);
+		break;
+	case FUTEX_OP_OR:
+		__futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
+		break;
+	case FUTEX_OP_ANDN:
+		__futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
+		break;
+	case FUTEX_OP_XOR:
+		__futex_atomic_op2("xorl %4, %3", 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(u32 *uval, u32 __user *uaddr,
+						u32 oldval, u32 newval)
+{
+	return user_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval);
+}
+
+#endif
+#endif /* _ASM_X86_FUTEX_H */
-- 
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