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-rw-r--r--arch/riscv/include/asm/futex.h104
1 files changed, 104 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/futex.h b/arch/riscv/include/asm/futex.h
new file mode 100644
index 0000000000..fc8130f995
--- /dev/null
+++ b/arch/riscv/include/asm/futex.h
@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2006 Ralf Baechle (ralf@linux-mips.org)
+ * Copyright (c) 2018 Jim Wilson (jimw@sifive.com)
+ */
+
+#ifndef _ASM_RISCV_FUTEX_H
+#define _ASM_RISCV_FUTEX_H
+
+#include <linux/futex.h>
+#include <linux/uaccess.h>
+#include <linux/errno.h>
+#include <asm/asm.h>
+#include <asm/asm-extable.h>
+
+/* We don't even really need the extable code, but for now keep it simple */
+#ifndef CONFIG_MMU
+#define __enable_user_access() do { } while (0)
+#define __disable_user_access() do { } while (0)
+#endif
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
+{ \
+ __enable_user_access(); \
+ __asm__ __volatile__ ( \
+ "1: " insn " \n" \
+ "2: \n" \
+ _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %[r]) \
+ : [r] "+r" (ret), [ov] "=&r" (oldval), \
+ [u] "+m" (*uaddr) \
+ : [op] "Jr" (oparg) \
+ : "memory"); \
+ __disable_user_access(); \
+}
+
+static inline int
+arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
+{
+ int oldval = 0, ret = 0;
+
+ if (!access_ok(uaddr, sizeof(u32)))
+ return -EFAULT;
+
+ switch (op) {
+ case FUTEX_OP_SET:
+ __futex_atomic_op("amoswap.w.aqrl %[ov],%z[op],%[u]",
+ ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ADD:
+ __futex_atomic_op("amoadd.w.aqrl %[ov],%z[op],%[u]",
+ ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_OR:
+ __futex_atomic_op("amoor.w.aqrl %[ov],%z[op],%[u]",
+ ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ANDN:
+ __futex_atomic_op("amoand.w.aqrl %[ov],%z[op],%[u]",
+ ret, oldval, uaddr, ~oparg);
+ break;
+ case FUTEX_OP_XOR:
+ __futex_atomic_op("amoxor.w.aqrl %[ov],%z[op],%[u]",
+ ret, oldval, uaddr, oparg);
+ break;
+ default:
+ ret = -ENOSYS;
+ }
+
+ if (!ret)
+ *oval = oldval;
+
+ return ret;
+}
+
+static inline int
+futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
+ u32 oldval, u32 newval)
+{
+ int ret = 0;
+ u32 val;
+ uintptr_t tmp;
+
+ if (!access_ok(uaddr, sizeof(u32)))
+ return -EFAULT;
+
+ __enable_user_access();
+ __asm__ __volatile__ (
+ "1: lr.w.aqrl %[v],%[u] \n"
+ " bne %[v],%z[ov],3f \n"
+ "2: sc.w.aqrl %[t],%z[nv],%[u] \n"
+ " bnez %[t],1b \n"
+ "3: \n"
+ _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %[r]) \
+ _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %[r]) \
+ : [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), [t] "=&r" (tmp)
+ : [ov] "Jr" (oldval), [nv] "Jr" (newval)
+ : "memory");
+ __disable_user_access();
+
+ *uval = val;
+ return ret;
+}
+
+#endif /* _ASM_RISCV_FUTEX_H */