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Diffstat (limited to 'arch/arm/include/asm/futex.h')
-rw-r--r--arch/arm/include/asm/futex.h124
1 files changed, 121 insertions, 3 deletions
diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h
index 6a332a9f099..9ee743b95de 100644
--- a/arch/arm/include/asm/futex.h
+++ b/arch/arm/include/asm/futex.h
@@ -1,6 +1,124 @@
-#ifndef _ASM_FUTEX_H
-#define _ASM_FUTEX_H
+#ifndef _ASM_ARM_FUTEX_H
+#define _ASM_ARM_FUTEX_H
+
+#ifdef __KERNEL__
+
+#ifdef CONFIG_SMP
#include <asm-generic/futex.h>
-#endif
+#else /* !SMP, we can work around lack of atomic ops by disabling preemption */
+
+#include <linux/futex.h>
+#include <linux/preempt.h>
+#include <linux/uaccess.h>
+#include <asm/errno.h>
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
+ __asm__ __volatile__( \
+ "1: ldrt %1, [%2]\n" \
+ " " insn "\n" \
+ "2: strt %0, [%2]\n" \
+ " mov %0, #0\n" \
+ "3:\n" \
+ " .section __ex_table,\"a\"\n" \
+ " .align 3\n" \
+ " .long 1b, 4f, 2b, 4f\n" \
+ " .previous\n" \
+ " .section .fixup,\"ax\"\n" \
+ "4: mov %0, %4\n" \
+ " b 3b\n" \
+ " .previous" \
+ : "=&r" (ret), "=&r" (oldval) \
+ : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
+ : "cc", "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(); /* implies preempt_disable() */
+
+ switch (op) {
+ case FUTEX_OP_SET:
+ __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ADD:
+ __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_OR:
+ __futex_atomic_op("orr %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ANDN:
+ __futex_atomic_op("and %0, %1, %3", ret, oldval, uaddr, ~oparg);
+ break;
+ case FUTEX_OP_XOR:
+ __futex_atomic_op("eor %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ default:
+ ret = -ENOSYS;
+ }
+
+ pagefault_enable(); /* subsumes preempt_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 val;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+ return -EFAULT;
+
+ pagefault_disable(); /* implies preempt_disable() */
+
+ __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
+ "1: ldrt %0, [%3]\n"
+ " teq %0, %1\n"
+ "2: streqt %2, [%3]\n"
+ "3:\n"
+ " .section __ex_table,\"a\"\n"
+ " .align 3\n"
+ " .long 1b, 4f, 2b, 4f\n"
+ " .previous\n"
+ " .section .fixup,\"ax\"\n"
+ "4: mov %0, %4\n"
+ " b 3b\n"
+ " .previous"
+ : "=&r" (val)
+ : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
+ : "cc", "memory");
+
+ pagefault_enable(); /* subsumes preempt_enable() */
+
+ return val;
+}
+
+#endif /* !SMP */
+
+#endif /* __KERNEL__ */
+#endif /* _ASM_ARM_FUTEX_H */