summaryrefslogtreecommitdiffstats
path: root/arch/x86/include/asm/futex.h
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/include/asm/futex.h')
-rw-r--r--arch/x86/include/asm/futex.h140
1 files changed, 140 insertions, 0 deletions
diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h
new file mode 100644
index 000000000000..1f11ce44e956
--- /dev/null
+++ b/arch/x86/include/asm/futex.h
@@ -0,0 +1,140 @@
+#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/system.h>
+
+#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg) \
+ asm volatile("1:\t" insn "\n" \
+ "2:\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("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.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, 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, tem;
+
+ if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
+ oparg = 1 << oparg;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+ return -EFAULT;
+
+#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
+ /* Real i386 machines can only support FUTEX_OP_SET */
+ if (op != FUTEX_OP_SET && boot_cpu_data.x86 == 3)
+ return -ENOSYS;
+#endif
+
+ 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(int __user *uaddr, int oldval,
+ int newval)
+{
+
+#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
+ /* Real i386 machines have no cmpxchg instruction */
+ if (boot_cpu_data.x86 == 3)
+ return -ENOSYS;
+#endif
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+ return -EFAULT;
+
+ asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %3, %1\n"
+ "2:\t.section .fixup, \"ax\"\n"
+ "3:\tmov %2, %0\n"
+ "\tjmp 2b\n"
+ "\t.previous\n"
+ _ASM_EXTABLE(1b, 3b)
+ : "=a" (oldval), "+m" (*uaddr)
+ : "i" (-EFAULT), "r" (newval), "0" (oldval)
+ : "memory"
+ );
+
+ return oldval;
+}
+
+#endif
+#endif /* _ASM_X86_FUTEX_H */